diff --git a/src/main/java/com/econovation/third_project/agrregate/AdminPageQuery.java b/src/main/java/com/econovation/third_project/agrregate/AdminPageQuery.java
new file mode 100644
index 0000000..a2b73bf
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/agrregate/AdminPageQuery.java
@@ -0,0 +1,9 @@
+package com.econovation.third_project.agrregate;
+
+import java.util.List;
+
+public interface AdminPageQuery {
+    String getType();
+    List<?> execute();
+
+}
diff --git a/src/main/java/com/econovation/third_project/agrregate/AdminPageQueryAggregator.java b/src/main/java/com/econovation/third_project/agrregate/AdminPageQueryAggregator.java
new file mode 100644
index 0000000..69c5ed1
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/agrregate/AdminPageQueryAggregator.java
@@ -0,0 +1,52 @@
+package com.econovation.third_project.agrregate;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import org.springframework.stereotype.Component;
+
+//TODO: 제네릭?
+@Component
+public class AdminPageQueryAggregator {
+    private final Map<String, AdminPageQuery> queries;
+    public AdminPageQueryAggregator(List<AdminPageQuery> queries) {
+        this.queries = queries.stream()
+                .collect(Collectors.toMap(AdminPageQuery::getType, Function.identity()));
+    }
+
+    public Map<String, List<?>> aggregate(Set<String> requests){
+        List<AdminPageQuery> queriesToExecute = getQueriesToExecute(requests);
+        Map<String, CompletableFuture<List<?>>> executedQueries = executeQueriesAsync(queriesToExecute);
+        return aggregateResults(executedQueries);
+    }
+
+    private List<AdminPageQuery> getQueriesToExecute(Set<String> requests){
+        return requests.stream()
+                .map(request -> Optional.ofNullable(queries.get(request))
+                        .orElseThrow(IllegalArgumentException::new)
+                )
+                .toList();
+    }
+
+    private Map<String, CompletableFuture<List<?>>> executeQueriesAsync(List<AdminPageQuery> queriesToExecute){
+        return queriesToExecute.stream()
+                .collect(Collectors.toMap(
+                        AdminPageQuery::getType,
+                        query-> CompletableFuture.supplyAsync(query::execute)
+                ));
+    }
+
+    private Map<String, List<?>> aggregateResults(Map<String, CompletableFuture<List<?>>> executedQueries) {
+        return CompletableFuture.allOf(executedQueries.values().toArray(new CompletableFuture[0]))
+                .<Map<String, List<?>>>thenApply(v ->
+                        executedQueries.entrySet().stream()
+                                .collect(Collectors.toMap(Map.Entry::getKey, entry -> entry.getValue().join()))
+                )
+                .join();
+    }
+
+}
diff --git a/src/main/java/com/econovation/third_project/agrregate/PathQuery.java b/src/main/java/com/econovation/third_project/agrregate/PathQuery.java
new file mode 100644
index 0000000..cdd14f1
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/agrregate/PathQuery.java
@@ -0,0 +1,21 @@
+package com.econovation.third_project.agrregate;
+
+import com.econovation.third_project.service.PathService;
+import java.util.List;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Component;
+
+@Component
+@RequiredArgsConstructor
+public class PathQuery implements AdminPageQuery{
+    private final PathService pathService;
+    @Override
+    public String getType() {
+        return "path";
+    }
+
+    @Override
+    public List<?> execute() {
+        return pathService.getApplicantNumberEachPath();
+    }
+}
diff --git a/src/main/java/com/econovation/third_project/config/Field.java b/src/main/java/com/econovation/third_project/config/Field.java
new file mode 100644
index 0000000..3d9ebb2
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/config/Field.java
@@ -0,0 +1,20 @@
+package com.econovation.third_project.config;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+@Getter
+public enum Field {
+    WEB("WEB"),
+    APP("APP"),
+    AI("AI"),
+    GAME("GAME"),
+    IOT("IoT"),
+    ARVR("AR/VR"),
+    NONE("선택없음");
+
+    private final String fieldName;
+
+
+}
diff --git a/src/main/java/com/econovation/third_project/config/Job.java b/src/main/java/com/econovation/third_project/config/Job.java
new file mode 100644
index 0000000..0c431da
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/config/Job.java
@@ -0,0 +1,14 @@
+package com.econovation.third_project.config;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+@Getter
+public enum Job {
+    DEVELOPER("개발자"),
+    PLANNER("기획자"),
+    DESIGNER("디자이너");
+
+    private final String jobName;
+}
diff --git a/src/main/java/com/econovation/third_project/config/SupportPath.java b/src/main/java/com/econovation/third_project/config/SupportPath.java
new file mode 100644
index 0000000..be783e4
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/config/SupportPath.java
@@ -0,0 +1,16 @@
+package com.econovation.third_project.config;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+@Getter
+public enum SupportPath {
+    POSTER("홍보 포스터"),
+    DEPARTMENT_ANNOUNCEMENT("학과 공지사항"),
+    ACQUAINTANCE("지인 소개"),
+    INSTAGRAM("인스타그램"),
+    EVERYTIME("에브리타임");
+    private final String entryPathName;
+
+}
diff --git a/src/main/java/com/econovation/third_project/controller/AdminQueryController.java b/src/main/java/com/econovation/third_project/controller/AdminQueryController.java
index 4c15adb..5d911ce 100644
--- a/src/main/java/com/econovation/third_project/controller/AdminQueryController.java
+++ b/src/main/java/com/econovation/third_project/controller/AdminQueryController.java
@@ -1,28 +1,36 @@
 package com.econovation.third_project.controller;
 
-import com.econovation.third_project.database.Database;
-import com.econovation.third_project.database.Registration;
+import com.econovation.third_project.agrregate.AdminPageQueryAggregator;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.ResponseEntity;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.GetMapping;
-import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
 
 @Controller
 @RequiredArgsConstructor
+@RequestMapping("/api/admin")
 public class AdminQueryController {
-    private final Database database;
+    private final AdminPageQueryAggregator adminPageQueryAggregator;
 
-    // 예시 코드
-    @PostMapping("/registration")
-    public ResponseEntity<Object> postRegistrate(@RequestBody Registration registration) {
-        database.register(registration);
-        return ResponseEntity.ok().build();
-    }
-    @GetMapping("/registration")
-    public ResponseEntity<Registration> getRegistration(String userId) {
-        return ResponseEntity.ok().body(database.getRegistration(userId));
+    @GetMapping("/applicants/async-test")
+    public ResponseEntity<Map<String, List<?>>> getApplicantsInfo(@RequestBody Set<String> fields){
+        return ResponseEntity.ok().body(
+                adminPageQueryAggregator.aggregate(fields));
     }
 
+
+    //TODO:
+    // 병렬 스트림 + async의 장점,
+    // 병렬 스트림, async 각각 적절한 상황,
+    // 서비스 메서드마다 다른 인자가 필요한 경우,
+    // 일부 의존 관계가 있을경우 어떻게 처리할지
+    // 서비스 메서드 맵 어떻게 뺄지,
+    // 적절한 스레드 수 알아보기,
+    // 자바 비동기 기초,
+
 }
diff --git a/src/main/java/com/econovation/third_project/controller/ApplicationController.java b/src/main/java/com/econovation/third_project/controller/ApplicationController.java
new file mode 100644
index 0000000..ce15d15
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/controller/ApplicationController.java
@@ -0,0 +1,22 @@
+package com.econovation.third_project.controller;
+
+import com.econovation.third_project.dto.CreateApplicationReq;
+import com.econovation.third_project.service.ApplicationService;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RequestMapping("/api")
+@RequiredArgsConstructor
+@RestController
+public class ApplicationController {
+    private final ApplicationService applicationService;
+
+    @PostMapping("/application")
+    public ResponseEntity<Integer> createApplication(@RequestBody CreateApplicationReq createApplicationReq){
+        return ResponseEntity.ok().body(applicationService.createApplication(createApplicationReq));
+    }
+}
diff --git a/src/main/java/com/econovation/third_project/database/Application.java b/src/main/java/com/econovation/third_project/database/Application.java
new file mode 100644
index 0000000..2654ba9
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/database/Application.java
@@ -0,0 +1,36 @@
+package com.econovation.third_project.database;
+
+import java.util.concurrent.atomic.AtomicInteger;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NonNull;
+
+
+@Getter
+public final class Application {
+    private static final AtomicInteger lastUsedId = new AtomicInteger(0);
+    @NonNull
+    private final Integer applicationId = lastUsedId.getAndIncrement();
+    @NonNull
+    private final Registration registration;
+    @NonNull
+    private final PersonalInformation personalInformation;
+    @NonNull
+    private final Path path;
+    @NonNull
+    private final DesiredTime desiredTime;
+
+    @Builder
+    public Application(Registration registration, PersonalInformation personalInformation,
+            Path path,
+            DesiredTime desiredTime) {
+        this.registration = registration;
+        this.personalInformation = personalInformation;
+        this.path = path;
+        this.desiredTime = desiredTime;
+    }
+}
+
+
+
+
diff --git a/src/main/java/com/econovation/third_project/database/Database.java b/src/main/java/com/econovation/third_project/database/Database.java
index 33b8710..f7eee3c 100644
--- a/src/main/java/com/econovation/third_project/database/Database.java
+++ b/src/main/java/com/econovation/third_project/database/Database.java
@@ -1,8 +1,9 @@
 package com.econovation.third_project.database;
 
-import java.util.HashMap;
+import java.util.Collection;
 import java.util.Map;
-import java.util.UUID;
+import java.util.Random;
+import java.util.concurrent.ConcurrentHashMap;
 import org.springframework.stereotype.Component;
 
 /**
@@ -11,18 +12,65 @@
  */
 @Component
 public class Database {
-    private final Map<String, Registration> registration = new HashMap<>();
-    private final Map<String, Path> path = new HashMap<>();
-    private final Map<String, PersonalInformation> personalInformation = new HashMap<>();
-    private final Map<String, DesiredTime> desiredTime = new HashMap<>();
+    //key: user id, value: application id
+    private final Map<Integer, Integer> applications = new ConcurrentHashMap<>();
+    //key: application id
+    private final Map<Integer, Registration> registrations = new ConcurrentHashMap<>();
+    //key: application id
+    private final Map<Integer, Path> paths = new ConcurrentHashMap<>();
+    //key: application id
+    private final Map<Integer, PersonalInformation> personalInformation = new ConcurrentHashMap<>();
+    //key: application id
+    private final Map<Integer, DesiredTime> desiredTimes = new ConcurrentHashMap<>();
 
-
-    public void register(Registration registrationRequest) {
-        // 기본적으로 이전 제출시 등록된 정보가 있으면 덮어쓰기를 지원합니다.
-        registration.put(UUID.randomUUID().toString(), registrationRequest);
+    public Collection<Registration> getAllRegistrations(){
+        return registrations.values();
+    }
+    public Collection<PersonalInformation> getAllPersonalInformation(){
+        return personalInformation.values();
+    }
+    public Collection<Path> getAllPath() {
+        return paths.values();
+    }
+    public Collection<DesiredTime> getAllDesiredTime(){
+        return desiredTimes.values();
     }
 
-    public Registration getRegistration(String userId) {
-        return registration.get(userId);
+    //지원자는 userId가 없으니 같은 지원서인지 판단할 기준을 따로 만들어야 함
+    public Integer upsertApplication(Integer userId, Application application){
+        Integer applicationId = applications.computeIfAbsent(userId, k -> application.getApplicationId());
+        upsertRegistration(applicationId, application.getRegistration());
+        upsertPath(applicationId, application.getPath());
+        upsertDesiredTime(applicationId, application.getDesiredTime());
+        upsertPersonalInformation(applicationId, application.getPersonalInformation());
+        return applicationId;
+    }
+    public void upsertRegistration(Integer applicationId, Registration registration){
+        registrations.put(applicationId, registration);
+    }
+    public void upsertPath(Integer applicationId, Path path){
+        paths.put(applicationId, path);
+    }
+    public void upsertPersonalInformation(Integer applicationId, PersonalInformation personalInformation){
+        this.personalInformation.put(applicationId, personalInformation);
+    }
+    public void upsertDesiredTime(Integer applicationId, DesiredTime desiredTime){
+        desiredTimes.put(applicationId, desiredTime);
     }
+
+
+
+//    public void register(Registration registrationRequest) {
+//        // 기본적으로 이전 제출시 등록된 정보가 있으면 덮어쓰기를 지원합니다.
+//        registration.put(UUID.randomUUID().toString(), registrationRequest);
+//    }
+//
+//    public Registration getRegistration(String userId) {
+//        return registration.get(userId);
+//    }
+
+
+
+
+
 }
\ No newline at end of file
diff --git a/src/main/java/com/econovation/third_project/database/DesiredTime.java b/src/main/java/com/econovation/third_project/database/DesiredTime.java
index 2d7a140..475fe64 100644
--- a/src/main/java/com/econovation/third_project/database/DesiredTime.java
+++ b/src/main/java/com/econovation/third_project/database/DesiredTime.java
@@ -1,13 +1,32 @@
 package com.econovation.third_project.database;
 
+import java.util.HashMap;
 import java.util.List;
-import lombok.AllArgsConstructor;
+import java.util.Map;
 import lombok.Getter;
 
-@AllArgsConstructor
 @Getter
 public class DesiredTime {
-    String registrationId;
-    // 희망 시간 (11 * 3)의 테이블 형태를 준수합니다.
-    private List<int[]> desiredTime;
+    private static final Map<List<Integer>, List<Integer>> cachedTimes = new HashMap<>();
+    private final List<List<Integer>> desiredTimes;
+
+    public DesiredTime(List<List<Integer>> desiredTimes) {
+        validateDesiredTime(desiredTimes);
+        this.desiredTimes = desiredTimes.stream()
+                .map(time-> cachedTimes.computeIfAbsent(time, t->t))
+                .toList();
+    }
+    private void validateDesiredTime(List<List<Integer>> desiredTimes) {
+        //27기 기준
+        int interviewDays = 3;
+        int hoursPerDay = 11;
+
+        desiredTimes.forEach(
+                time -> {
+                    if (time.get(0) >= interviewDays || time.get(1) >= hoursPerDay)
+                        throw new IllegalArgumentException("면접 시간 잘못 입력");
+                }
+        );
+
+    }
 }
diff --git a/src/main/java/com/econovation/third_project/database/Path.java b/src/main/java/com/econovation/third_project/database/Path.java
index 727433c..b7ddc9a 100644
--- a/src/main/java/com/econovation/third_project/database/Path.java
+++ b/src/main/java/com/econovation/third_project/database/Path.java
@@ -1,12 +1,27 @@
 package com.econovation.third_project.database;
 
+import com.econovation.third_project.config.SupportPath;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collector;
 import lombok.AllArgsConstructor;
 import lombok.Getter;
 
-@AllArgsConstructor
 @Getter
-public class Path {
-    String registrationId;
+public class Path{
     // 지원 경로
-    private String supportPath;
+    private final EnumSet<SupportPath> supportPaths;
+
+    public Path(EnumSet<SupportPath> supportPaths) {
+        this.supportPaths = supportPaths;
+    }
+
+    public static Path from(Set<String> stringPaths){
+        EnumSet<SupportPath> enumPaths = EnumSet.noneOf(SupportPath.class);
+        stringPaths.stream()
+                .forEach(stringPath-> enumPaths.add(SupportPath.valueOf(stringPath.toUpperCase())));
+        return new Path(enumPaths);
+    }
 }
diff --git a/src/main/java/com/econovation/third_project/database/PersonalInformation.java b/src/main/java/com/econovation/third_project/database/PersonalInformation.java
index 8a17b8a..40f8c7a 100644
--- a/src/main/java/com/econovation/third_project/database/PersonalInformation.java
+++ b/src/main/java/com/econovation/third_project/database/PersonalInformation.java
@@ -1,12 +1,13 @@
 package com.econovation.third_project.database;
 
+import java.util.Optional;
 import lombok.AllArgsConstructor;
+import lombok.Builder;
 import lombok.Getter;
 
-@AllArgsConstructor
 @Getter
+@Builder
 public class PersonalInformation {
-    private String registrationId;
 
     // 이름
     private String name;
@@ -31,8 +32,15 @@ public class PersonalInformation {
     // 부전공
     private String minor;
 
-
-
     // 이메일
     private String email;
+
+    public Optional<String> getDoubleMajor() {
+        return Optional.ofNullable(this.doubleMajor);
+    }
+
+    public Optional<String> getMinor() {
+        return Optional.ofNullable(this.minor);
+    }
+
 }
diff --git a/src/main/java/com/econovation/third_project/database/Registration.java b/src/main/java/com/econovation/third_project/database/Registration.java
index be42739..e1df4c6 100644
--- a/src/main/java/com/econovation/third_project/database/Registration.java
+++ b/src/main/java/com/econovation/third_project/database/Registration.java
@@ -1,21 +1,30 @@
 package com.econovation.third_project.database;
 
+import com.econovation.third_project.config.Field;
+import com.econovation.third_project.config.Job;
+import java.util.Optional;
+import lombok.AccessLevel;
+import lombok.AllArgsConstructor;
 import lombok.Getter;
+import lombok.NonNull;
 
 @Getter
+@AllArgsConstructor(access = AccessLevel.PRIVATE)
 public class Registration {
-    // 희망분야
-    private String hopeField;
+    @NonNull
+    private Job hopeJob;
+    @NonNull
+    private Field firstPriority;
+    @Getter
+    private Field secondPriority;
 
-    // 1지망
-    private String firstPriority;
+    public static Registration of(@NonNull String hopeJob, @NonNull String firstJobFieldName, String secondJobFieldName){
+        Job job = Job.valueOf(hopeJob.toUpperCase());
 
-    // 2지망
-    private String secondPriority;
+        Field firstPriority = Field.valueOf(firstJobFieldName.toUpperCase());
+        Field secondPriority = Field.valueOf(secondJobFieldName.toUpperCase());
 
-    public Registration(String hopeField, String firstPriority, String secondPriority) {
-        this.hopeField = hopeField;
-        this.firstPriority = firstPriority;
-        this.secondPriority = secondPriority;
+        return new Registration(job, firstPriority, secondPriority);
     }
+
 }
diff --git a/src/main/java/com/econovation/third_project/database/User.java b/src/main/java/com/econovation/third_project/database/User.java
new file mode 100644
index 0000000..79f2eec
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/database/User.java
@@ -0,0 +1,12 @@
+package com.econovation.third_project.database;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class User {
+    private static final AtomicInteger lastUsedId = new AtomicInteger(0);
+
+    private static int nextId(){
+        return lastUsedId.getAndIncrement();
+    }
+
+}
diff --git a/src/main/java/com/econovation/third_project/dto/ApplicantNumberInField.java b/src/main/java/com/econovation/third_project/dto/ApplicantNumberInField.java
new file mode 100644
index 0000000..59b277d
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/dto/ApplicantNumberInField.java
@@ -0,0 +1,19 @@
+package com.econovation.third_project.dto;
+
+import com.econovation.third_project.config.Field;
+import java.util.Map.Entry;
+
+public record ApplicantNumberInField(String fieldName, int firstNumber, int secondNumber) implements Comparable<ApplicantNumberInField>{
+    @Override
+    public int compareTo(ApplicantNumberInField o) {
+        return (this.firstNumber+this.secondNumber) - (o.firstNumber + o.secondNumber);
+    }
+
+    public ApplicantNumberInField(Entry<Field, int[]> entry) {
+        this(
+                entry.getKey().getFieldName(),
+                entry.getValue()[0],
+                entry.getValue()[1]
+        );
+    }
+}
diff --git a/src/main/java/com/econovation/third_project/dto/ApplicantNumberInJob.java b/src/main/java/com/econovation/third_project/dto/ApplicantNumberInJob.java
new file mode 100644
index 0000000..08440d9
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/dto/ApplicantNumberInJob.java
@@ -0,0 +1,5 @@
+package com.econovation.third_project.dto;
+
+public record ApplicantNumberInJob(String jobName, int number) {
+
+}
diff --git a/src/main/java/com/econovation/third_project/dto/ApplicantNumberInMajor.java b/src/main/java/com/econovation/third_project/dto/ApplicantNumberInMajor.java
new file mode 100644
index 0000000..454b647
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/dto/ApplicantNumberInMajor.java
@@ -0,0 +1,5 @@
+package com.econovation.third_project.dto;
+
+public record ApplicantNumberInMajor(String majorName, int number){
+
+}
diff --git a/src/main/java/com/econovation/third_project/dto/ApplicantNumberInPath.java b/src/main/java/com/econovation/third_project/dto/ApplicantNumberInPath.java
new file mode 100644
index 0000000..14ca7f7
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/dto/ApplicantNumberInPath.java
@@ -0,0 +1,5 @@
+package com.econovation.third_project.dto;
+
+public record ApplicantNumberInPath(String entryPathName, int number){
+
+}
diff --git a/src/main/java/com/econovation/third_project/dto/ApplicantNumberInTime.java b/src/main/java/com/econovation/third_project/dto/ApplicantNumberInTime.java
new file mode 100644
index 0000000..6946684
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/dto/ApplicantNumberInTime.java
@@ -0,0 +1,7 @@
+package com.econovation.third_project.dto;
+
+import java.util.List;
+
+public record ApplicantNumberInTime(List<Integer> time, int number) {
+
+}
diff --git a/src/main/java/com/econovation/third_project/dto/CreateApplicationReq.java b/src/main/java/com/econovation/third_project/dto/CreateApplicationReq.java
new file mode 100644
index 0000000..1962db6
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/dto/CreateApplicationReq.java
@@ -0,0 +1,17 @@
+package com.econovation.third_project.dto;
+
+import com.fasterxml.jackson.databind.PropertyNamingStrategies;
+import com.fasterxml.jackson.databind.annotation.JsonNaming;
+import lombok.NonNull;
+
+@JsonNaming(PropertyNamingStrategies.SnakeCaseStrategy.class)
+public record CreateApplicationReq(
+        @NonNull
+        RegistrationReq registration,
+        @NonNull
+        PersonalInformationReq personalInformation,
+        @NonNull
+        PathReq path,
+        @NonNull
+        DesiredTimeReq desiredTime
+        ){}
diff --git a/src/main/java/com/econovation/third_project/dto/DesiredTimeReq.java b/src/main/java/com/econovation/third_project/dto/DesiredTimeReq.java
new file mode 100644
index 0000000..97db7ea
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/dto/DesiredTimeReq.java
@@ -0,0 +1,10 @@
+package com.econovation.third_project.dto;
+
+import com.econovation.third_project.database.DesiredTime;
+import java.util.List;
+
+public record DesiredTimeReq(List<List<Integer>> desiredTimes){
+    public DesiredTime toEntity(){
+        return new DesiredTime(desiredTimes);
+    }
+}
diff --git a/src/main/java/com/econovation/third_project/dto/PathReq.java b/src/main/java/com/econovation/third_project/dto/PathReq.java
new file mode 100644
index 0000000..b6bf969
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/dto/PathReq.java
@@ -0,0 +1,10 @@
+package com.econovation.third_project.dto;
+
+import com.econovation.third_project.database.Path;
+import java.util.Set;
+
+public record PathReq(Set<String> paths) {
+    public Path toEntity(){
+        return Path.from(paths);
+    }
+}
diff --git a/src/main/java/com/econovation/third_project/dto/PersonalInformationReq.java b/src/main/java/com/econovation/third_project/dto/PersonalInformationReq.java
new file mode 100644
index 0000000..e0abbde
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/dto/PersonalInformationReq.java
@@ -0,0 +1,28 @@
+package com.econovation.third_project.dto;
+
+import com.econovation.third_project.database.PersonalInformation;
+
+public record PersonalInformationReq(
+        String name,
+        String phoneNumber,
+        Integer studentId,
+        Integer grade,
+        Integer semester,
+        String major,
+        String doubleMajor,
+        String minor,
+        String email) {
+    public PersonalInformation toEntity(){
+        return PersonalInformation.builder()
+                .name(this.name)
+                .doubleMajor(this.doubleMajor)
+                .email(this.email)
+                .grade(this.grade)
+                .major(this.major)
+                .minor(this.minor)
+                .phoneNumber(this.phoneNumber)
+                .semester(this.semester)
+                .studentId(this.studentId)
+                .build();
+    }
+}
diff --git a/src/main/java/com/econovation/third_project/dto/PostRegistrationRes.java b/src/main/java/com/econovation/third_project/dto/PostRegistrationRes.java
new file mode 100644
index 0000000..e247f17
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/dto/PostRegistrationRes.java
@@ -0,0 +1,5 @@
+package com.econovation.third_project.dto;
+
+public record PostRegistrationRes(String registrationId) {
+
+}
diff --git a/src/main/java/com/econovation/third_project/dto/RegistrationReq.java b/src/main/java/com/econovation/third_project/dto/RegistrationReq.java
new file mode 100644
index 0000000..b02f82c
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/dto/RegistrationReq.java
@@ -0,0 +1,12 @@
+package com.econovation.third_project.dto;
+
+import com.econovation.third_project.database.Registration;
+
+public record RegistrationReq(String job, String firstPriority, String secondPriority) {
+    public RegistrationReq{
+        System.out.println(job);
+    }
+    public Registration toEntity(){
+        return Registration.of(this.job, this.firstPriority, this.secondPriority);
+    }
+}
diff --git a/src/main/java/com/econovation/third_project/service/ApplicationService.java b/src/main/java/com/econovation/third_project/service/ApplicationService.java
new file mode 100644
index 0000000..d702f3b
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/service/ApplicationService.java
@@ -0,0 +1,23 @@
+package com.econovation.third_project.service;
+
+import com.econovation.third_project.database.Application;
+import com.econovation.third_project.database.Database;
+import com.econovation.third_project.dto.CreateApplicationReq;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+
+@Service
+@RequiredArgsConstructor
+public class ApplicationService {
+    private final Database db;
+    public int createApplication(CreateApplicationReq createApplicationReq){
+        Application application = Application.builder()
+                .registration(createApplicationReq.registration().toEntity())
+                .personalInformation(createApplicationReq.personalInformation().toEntity())
+                .path(createApplicationReq.path().toEntity())
+                .desiredTime(createApplicationReq.desiredTime().toEntity())
+                .build();
+        return db.upsertApplication(1, application);
+    }
+
+}
diff --git a/src/main/java/com/econovation/third_project/service/DesiredTimeService.java b/src/main/java/com/econovation/third_project/service/DesiredTimeService.java
new file mode 100644
index 0000000..bbe21cb
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/service/DesiredTimeService.java
@@ -0,0 +1,32 @@
+package com.econovation.third_project.service;
+
+import com.econovation.third_project.database.Database;
+import com.econovation.third_project.dto.ApplicantNumberInJob;
+import com.econovation.third_project.dto.ApplicantNumberInTime;
+import java.util.List;
+import java.util.stream.Collectors;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+
+@Service
+@RequiredArgsConstructor
+public class DesiredTimeService {
+    private final Database db;
+
+    //입력할 때 2개인지 확인해야 함
+
+    public List<ApplicantNumberInTime> getApplicantNumberEachTime(){
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+        return db.getAllDesiredTime().stream()
+                .flatMap(desiredTime -> desiredTime.getDesiredTimes().stream())
+                .collect(Collectors.groupingBy(time -> time, Collectors.counting()))
+                .entrySet().stream()
+                .map(entry->new ApplicantNumberInTime(entry.getKey(), entry.getValue().intValue()))
+                .toList();
+    }
+
+}
diff --git a/src/main/java/com/econovation/third_project/service/PathService.java b/src/main/java/com/econovation/third_project/service/PathService.java
new file mode 100644
index 0000000..84158c5
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/service/PathService.java
@@ -0,0 +1,30 @@
+package com.econovation.third_project.service;
+
+import com.econovation.third_project.database.Database;
+import com.econovation.third_project.dto.ApplicantNumberInPath;
+import java.util.List;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+
+@Service
+@RequiredArgsConstructor
+public class PathService {
+    private final Database db;
+
+    public List<ApplicantNumberInPath> getApplicantNumberEachPath(){
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+        return db.getAllPath().stream()
+                .flatMap(path-> path.getSupportPaths().stream())
+                .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()))
+                .entrySet().stream()
+                .map(entry->new ApplicantNumberInPath(entry.getKey().getEntryPathName(), entry.getValue().intValue()))
+                .toList();
+    }
+
+}
diff --git a/src/main/java/com/econovation/third_project/service/PersonalInformationService.java b/src/main/java/com/econovation/third_project/service/PersonalInformationService.java
new file mode 100644
index 0000000..b53964f
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/service/PersonalInformationService.java
@@ -0,0 +1,36 @@
+package com.econovation.third_project.service;
+
+import com.econovation.third_project.database.Database;
+import com.econovation.third_project.dto.ApplicantNumberInMajor;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+
+@Service
+@RequiredArgsConstructor
+public class PersonalInformationService {
+    private final Database db;
+
+    //학과별 지원자 수
+    public List<ApplicantNumberInMajor> getApplicantNumberEachMajor(){
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+
+        return db.getAllPersonalInformation().stream()
+                .flatMap(info-> Stream.of(info.getMajor(), info.getDoubleMajor().orElse(null)))
+                .filter(Objects::nonNull)
+                .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()))
+                .entrySet().stream()
+                .map(entry-> new ApplicantNumberInMajor(entry.getKey(), entry.getValue().intValue()))
+                .toList();
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/econovation/third_project/service/RegistrationService.java b/src/main/java/com/econovation/third_project/service/RegistrationService.java
new file mode 100644
index 0000000..9d93610
--- /dev/null
+++ b/src/main/java/com/econovation/third_project/service/RegistrationService.java
@@ -0,0 +1,74 @@
+package com.econovation.third_project.service;
+
+
+import com.econovation.third_project.database.Database;
+import com.econovation.third_project.config.Field;
+import com.econovation.third_project.config.Job;
+import com.econovation.third_project.database.Registration;
+import com.econovation.third_project.dto.ApplicantNumberInJob;
+import com.econovation.third_project.dto.ApplicantNumberInField;
+import static java.util.Comparator.reverseOrder;
+
+import java.util.Collection;
+import java.util.EnumMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+
+
+
+
+@Service
+@RequiredArgsConstructor
+public class RegistrationService {
+    private final Database db;
+
+    //분야별 지원자 수
+    public List<ApplicantNumberInJob> getApplicantNumbersEachJob(){
+        return db.getAllRegistrations().stream()
+                .collect(Collectors.groupingBy(Registration::getHopeJob, Collectors.counting()))
+                .entrySet().stream()
+                .sorted(Map.Entry.<Job, Long>comparingByValue().reversed())
+                .map(entry->new ApplicantNumberInJob(entry.getKey().getJobName(), entry.getValue().intValue()))
+                .toList();
+    }
+
+    //세부 분야별 지원자 수
+    public List<ApplicantNumberInField> getApplicantNumberEachField(){
+        return PriorityCounts.of(db.getAllRegistrations())
+                .getJobPriorityCounts()
+                .entrySet().stream()
+                .map(ApplicantNumberInField::new)
+                .sorted(reverseOrder())
+                .toList();
+    }
+
+}
+
+@Getter
+final class PriorityCounts{
+    private final Map<Field, int[]> jobPriorityCounts = new EnumMap<>(Field.class);
+
+    private PriorityCounts() {
+        for (Field field : Field.values())
+            jobPriorityCounts.put(field, new int[2]);
+    }
+    static PriorityCounts of(Collection<Registration> registrations){
+        PriorityCounts priorityCounts = new PriorityCounts();
+        registrations.forEach(regi->{
+                    priorityCounts.incrementFirstPriority(regi.getFirstPriority());
+                    priorityCounts.incrementSecondPriority(regi.getSecondPriority());
+                });
+        return priorityCounts;
+    }
+
+    private void incrementFirstPriority(Field field){
+        jobPriorityCounts.get(field)[0]++;
+    }
+    private void incrementSecondPriority(Field field){
+        jobPriorityCounts.get(field)[1]++;
+    }
+}