diff --git a/src/main/java/com/sajang/devracebackend/controller/AuthController.java b/src/main/java/com/sajang/devracebackend/controller/AuthController.java
index 224569e..664ff24 100644
--- a/src/main/java/com/sajang/devracebackend/controller/AuthController.java
+++ b/src/main/java/com/sajang/devracebackend/controller/AuthController.java
@@ -37,17 +37,17 @@ public ResponseEntity<ResponseData<AuthDto.SignupResponse>> signup(
         return ResponseData.toResponseEntity(ResponseCode.CREATED_USER, signupResponseDto);  // 이 reponseDto 내에 새로운 JWT Access 토큰이 들어있음. 이후 앞으로는 이걸로 헤더에 장착해야함.
     }
 
-    @PostMapping("/reissue")
-    @Operation(summary = "JWT Access Token 재발급 [JWT X]")
-    public ResponseEntity<ResponseData<AuthDto.TokenResponse>> reissue(@RequestBody AuthDto.ReissueRequest reissueRequestDto) {
-        AuthDto.TokenResponse tokenResponseDto = authService.reissue(reissueRequestDto);
-        return ResponseData.toResponseEntity(ResponseCode.REISSUE_SUCCESS, tokenResponseDto);
-    }
-
     @DeleteMapping("/users")
     @Operation(summary = "마이 Page - 회원탈퇴 [JWT O]")
     public ResponseEntity<ResponseData> withdrawal() {
         authService.withdrawal();
         return ResponseData.toResponseEntity(ResponseCode.DELETE_USER);
     }
+
+    @PostMapping("/reissue")
+    @Operation(summary = "로그인 유지 - JWT Access Token 재발급 [JWT X]")
+    public ResponseEntity<ResponseData<AuthDto.TokenResponse>> reissue(@RequestBody AuthDto.ReissueRequest reissueRequestDto) {
+        AuthDto.TokenResponse tokenResponseDto = authService.reissue(reissueRequestDto);
+        return ResponseData.toResponseEntity(ResponseCode.REISSUE_SUCCESS, tokenResponseDto);
+    }
 }
diff --git a/src/main/java/com/sajang/devracebackend/controller/RoomController.java b/src/main/java/com/sajang/devracebackend/controller/RoomController.java
index be5d077..7a18ad2 100644
--- a/src/main/java/com/sajang/devracebackend/controller/RoomController.java
+++ b/src/main/java/com/sajang/devracebackend/controller/RoomController.java
@@ -37,24 +37,34 @@ public ResponseEntity<ResponseData<RoomDto.Response>> createRoom(@RequestBody Pr
     }
 
     @GetMapping("/rooms")
-    @Operation(summary = "초대링크 방 조회 [JWT O]", description = "URI : /rooms?link={방링크 string}")
+    @Operation(summary = "초대 접속 - 초대링크 방 조회 [JWT O]", description = "URI : /rooms?link={방링크 string}")
     public ResponseEntity<ResponseData<RoomDto.Response>> findRoomByLink(@RequestParam(value = "link", required = true) String link) {
         RoomDto.Response roomResponseDto = roomService.findRoomByLink(link);
         return ResponseData.toResponseEntity(ResponseCode.READ_ROOM, roomResponseDto);
     }
 
+    @PutMapping("/rooms/{roomId}")
+    @Operation(summary = "입장 Page - 방 입장 대기열 나가기 [JWT O]")
+    public ResponseEntity<ResponseData> userStopWaitRoom(@PathVariable(value = "roomId") Long roomId) {
+        userRoomService.userStopWaitRoom(roomId);
+        return ResponseData.toResponseEntity(ResponseCode.UPDATE_ROOM);
+    }
+
     @GetMapping("/rooms/{roomId}")
     @Operation(summary = "문제풀이 Page - 문제풀이 페이지 정보 조회 [JWT O]")
-    public ResponseEntity<ResponseData<UserRoomDto.SolvePageResponse>> loadSolvingPage(@PathVariable(value = "roomId") Long roomId) {  // value=""를 작성해주어야만, Swagger에서 api테스트할때 이름값이 뜸.
-        UserRoomDto.SolvePageResponse solvePageResponseDto = userRoomService.loadSolvingPage(roomId);
+    public ResponseEntity<ResponseData<UserRoomDto.SolvePageResponse>> loadSolvePage(@PathVariable(value = "roomId") Long roomId) {  // value=""를 작성해주어야만, Swagger에서 api테스트할때 이름값이 뜸.
+        UserRoomDto.SolvePageResponse solvePageResponseDto = userRoomService.loadSolvePage(roomId);
         return ResponseData.toResponseEntity(ResponseCode.READ_USERROOM, solvePageResponseDto);
     }
 
-    @GetMapping("/rooms/{roomId}/access-check")
-    @Operation(summary = "문제풀이 Page - 문제풀이 페이지 접근허용 검사 [JWT O]", description = "isLeave == 0 or 1 or null")
-    public ResponseEntity<ResponseData<UserRoomDto.CheckAccessResponse>> checkAccess(@PathVariable(value = "roomId") Long roomId) {
-        UserRoomDto.CheckAccessResponse checkAccessResponseDto = userRoomService.checkAccess(roomId);
-        return ResponseData.toResponseEntity(ResponseCode.READ_USERROOM, checkAccessResponseDto);
+    @PostMapping("/rooms/{roomId}")  // 의미상 PUT보단 POST가 더 적합하다고 판단했음.
+    @Operation(summary = "문제풀이 Page - 문제풀이 성공 및 실패/퇴장 [JWT O]", description = "isRetry==0 : 첫풀이 경우 / isRetry==1 : 재풀이 경우")
+    public ResponseEntity<ResponseData> solveProblem(
+            @PathVariable(value = "roomId") Long roomId,
+            @RequestBody UserRoomDto.SolveRequest solveRequest) {
+
+        userRoomService.solveProblem(roomId, solveRequest);
+        return ResponseData.toResponseEntity(ResponseCode.UPDATE_USERROOM);  // 비록 POST이지만, 비즈니스 로직은 update임.
     }
 
     @GetMapping("/rooms/{roomId}/state-check")
@@ -64,21 +74,11 @@ public ResponseEntity<ResponseData<RoomDto.CheckStateResponse>> checkState(@Path
         return ResponseData.toResponseEntity(ResponseCode.READ_USERROOM, checkStateResponseDto);
     }
 
-    @PostMapping("/rooms/{roomId}")  // 의미상 PUT보단 POST가 더 적합하다고 판단했음.
-    @Operation(summary = "문제풀이 Page - 문제풀이 성공 및 실패/퇴장 [JWT O]", description = "isRetry==0 : 첫풀이 경우 / isRetry==1 : 재풀이 경우")
-    public ResponseEntity<ResponseData> passSolvingProblem(
-            @PathVariable(value = "roomId") Long roomId,
-            @RequestBody UserRoomDto.SolveRequest solveRequest) {
-
-        userRoomService.passSolvingProblem(roomId, solveRequest);
-        return ResponseData.toResponseEntity(ResponseCode.UPDATE_USERROOM);  // 비록 POST이지만, 비즈니스 로직은 update임.
-    }
-
-    @PutMapping("/rooms/{roomId}")
-    @Operation(summary = "입장 Page - 방 입장 대기열 나가기 [JWT O]")
-    public ResponseEntity<ResponseData> userStopWaitRoom(@PathVariable(value = "roomId") Long roomId) {
-        userRoomService.userStopWaitRoom(roomId);
-        return ResponseData.toResponseEntity(ResponseCode.UPDATE_ROOM);
+    @GetMapping("/rooms/{roomId}/access-check")
+    @Operation(summary = "문제풀이 Page - 문제풀이 페이지 접근허용 검사 [JWT O]", description = "isLeave == 0 or 1 or null")
+    public ResponseEntity<ResponseData<UserRoomDto.CheckAccessResponse>> checkAccess(@PathVariable(value = "roomId") Long roomId) {
+        UserRoomDto.CheckAccessResponse checkAccessResponseDto = userRoomService.checkAccess(roomId);
+        return ResponseData.toResponseEntity(ResponseCode.READ_USERROOM, checkAccessResponseDto);
     }
 
     @MessageMapping("wait.enter")  // 웹소켓 메시지 처리 (백엔드로 '/pub/wait.enter'를 호출시 이 브로커에서 처리)
diff --git a/src/main/java/com/sajang/devracebackend/controller/TestController.java b/src/main/java/com/sajang/devracebackend/controller/TestController.java
index d082bb8..5dd187d 100644
--- a/src/main/java/com/sajang/devracebackend/controller/TestController.java
+++ b/src/main/java/com/sajang/devracebackend/controller/TestController.java
@@ -16,7 +16,7 @@
 public class TestController {
 
     @GetMapping("/health")
-    @Operation(summary = "서버 헬스체크 [JWT X]")
+    @Operation(summary = "AWS - 서버 헬스체크 [JWT X]")
     public ResponseEntity<ResponseData> healthCheck() {
         return ResponseData.toResponseEntity(ResponseCode.HEALTHY_SUCCESS);
     }
diff --git a/src/main/java/com/sajang/devracebackend/controller/UserController.java b/src/main/java/com/sajang/devracebackend/controller/UserController.java
index b580086..be54ee8 100644
--- a/src/main/java/com/sajang/devracebackend/controller/UserController.java
+++ b/src/main/java/com/sajang/devracebackend/controller/UserController.java
@@ -51,6 +51,13 @@ public ResponseEntity<ResponseData> updateUserProfile(
         return ResponseData.toResponseEntity(ResponseCode.UPDATE_USER);
     }
 
+    @GetMapping("/users/solved-count")
+    @Operation(summary = "문제풀이 Page - 사용자 백준 solvedCount값 조회 [JWT O]")
+    public ResponseEntity<ResponseData<UserDto.SolvedCountResponse>> findUserSolvedCount() {
+        UserDto.SolvedCountResponse solvedCountResponseDto = userService.findUserSolvedCount();
+        return ResponseData.toResponseEntity(ResponseCode.READ_SOLVEDCOUNT, solvedCountResponseDto);
+    }
+
     @GetMapping("/users/rooms")
     @Operation(summary = "내 코드 Page - 코드방 목록 조회/정렬/검색 [JWT O]",
             description = """
@@ -69,15 +76,8 @@ public ResponseEntity<ResponseData<Page<UserRoomDto.CodePageResponse>>> findCode
 
     @GetMapping("/users/rooms-check")
     @Operation(summary = "메인 Page - 참여중인 방 여부 검사 [JWT O]", description = "roomId == Long or null")
-    public ResponseEntity<ResponseData<UserDto.CheckRoomResponse>> checkCurrentRoom() {
-        UserDto.CheckRoomResponse checkRoomResponseDto = userService.checkCurrentRoom();
+    public ResponseEntity<ResponseData<UserDto.CheckRoomResponse>> checkRoom() {
+        UserDto.CheckRoomResponse checkRoomResponseDto = userService.checkRoom();
         return ResponseData.toResponseEntity(ResponseCode.READ_ROOM, checkRoomResponseDto);
     }
-
-    @GetMapping("/users/solved-count")
-    @Operation(summary = "사용자 백준 solvedCount값 조회 [JWT O]")
-    public ResponseEntity<ResponseData<UserDto.SolvedCountResponse>> checkUserSolvedCount() {
-        UserDto.SolvedCountResponse solvedCountResponseDto = userService.checkUserSolvedCount();
-        return ResponseData.toResponseEntity(ResponseCode.READ_SOLVEDCOUNT, solvedCountResponseDto);
-    }
 }
diff --git a/src/main/java/com/sajang/devracebackend/dto/AuthDto.java b/src/main/java/com/sajang/devracebackend/dto/AuthDto.java
index aae2c41..2a69d2b 100644
--- a/src/main/java/com/sajang/devracebackend/dto/AuthDto.java
+++ b/src/main/java/com/sajang/devracebackend/dto/AuthDto.java
@@ -11,19 +11,19 @@ public class AuthDto {
 
     @Getter
     @NoArgsConstructor
-    public static class ReissueRequest {
+    public static class SignupRequest {
 
-        private String accessToken;
-        private String refreshToken;
+        private String nickname;
+        private String bojId;
+        private Integer isImageChange;
     }
 
     @Getter
     @NoArgsConstructor
-    public static class SignupRequest {
+    public static class ReissueRequest {
 
-        private String nickname;
-        private String bojId;
-        private Integer isImageChange;
+        private String accessToken;
+        private String refreshToken;
     }
 
 
@@ -33,21 +33,21 @@ public static class SignupRequest {
     @Getter
     @NoArgsConstructor
     @AllArgsConstructor
-    public static class TokenResponse {
+    public static class SignupResponse {
 
-        private String grantType;
-        private String accessToken;
-        private Long accessTokenExpiresIn;
-        private String refreshToken;
+        private UserDto.Response userResponseDto;
+        private AuthDto.TokenResponse tokenResponseDto;
     }
 
     @Builder
     @Getter
     @NoArgsConstructor
     @AllArgsConstructor
-    public static class SignupResponse {
+    public static class TokenResponse {
 
-        private UserDto.Response userResponseDto;
-        private AuthDto.TokenResponse tokenResponseDto;
+        private String grantType;
+        private String accessToken;
+        private Long accessTokenExpiresIn;
+        private String refreshToken;
     }
 }
diff --git a/src/main/java/com/sajang/devracebackend/dto/UserRoomDto.java b/src/main/java/com/sajang/devracebackend/dto/UserRoomDto.java
index 786d172..a1c34b0 100644
--- a/src/main/java/com/sajang/devracebackend/dto/UserRoomDto.java
+++ b/src/main/java/com/sajang/devracebackend/dto/UserRoomDto.java
@@ -3,8 +3,6 @@
 import com.sajang.devracebackend.domain.enums.Language;
 import com.sajang.devracebackend.domain.enums.RoomState;
 import com.sajang.devracebackend.domain.mapping.UserRoom;
-import com.sajang.devracebackend.dto.ProblemDto;
-import com.sajang.devracebackend.dto.UserDto;
 import lombok.AllArgsConstructor;
 import lombok.Builder;
 import lombok.Getter;
diff --git a/src/main/java/com/sajang/devracebackend/repository/UserRepository.java b/src/main/java/com/sajang/devracebackend/repository/UserRepository.java
index 7de886d..8f9b314 100644
--- a/src/main/java/com/sajang/devracebackend/repository/UserRepository.java
+++ b/src/main/java/com/sajang/devracebackend/repository/UserRepository.java
@@ -21,6 +21,6 @@ public interface UserRepository extends JpaRepository<User, Long> {
     // ===================== //
 
     Optional<User> findBySocialTypeAndSocialId(SocialType socialType, String socialId);  // '소셜 타입, 식별자'로 해당 회원을 찾기 위한 메소드 (차후 추가정보 입력 회원가입 가능)
-    boolean existsByBojId(String bojId);
     List<User> findByIdIn(List<Long> userIdList);
+    boolean existsByBojId(String bojId);
 }
\ No newline at end of file
diff --git a/src/main/java/com/sajang/devracebackend/service/AuthService.java b/src/main/java/com/sajang/devracebackend/service/AuthService.java
index 20f8cac..6e793a1 100644
--- a/src/main/java/com/sajang/devracebackend/service/AuthService.java
+++ b/src/main/java/com/sajang/devracebackend/service/AuthService.java
@@ -7,6 +7,6 @@
 
 public interface AuthService {
     AuthDto.SignupResponse signup(MultipartFile imageFile, AuthDto.SignupRequest SignupRequestDto) throws IOException;
-    AuthDto.TokenResponse reissue(AuthDto.ReissueRequest reissueRequestDto);
     void withdrawal();
+    AuthDto.TokenResponse reissue(AuthDto.ReissueRequest reissueRequestDto);
 }
\ No newline at end of file
diff --git a/src/main/java/com/sajang/devracebackend/service/ChatService.java b/src/main/java/com/sajang/devracebackend/service/ChatService.java
index dc262dd..27c1def 100644
--- a/src/main/java/com/sajang/devracebackend/service/ChatService.java
+++ b/src/main/java/com/sajang/devracebackend/service/ChatService.java
@@ -5,6 +5,6 @@
 import org.springframework.data.domain.Slice;
 
 public interface ChatService {
-    ChatDto.Response createChat(ChatDto.SaveRequest saveRequestDto);
     Slice<ChatDto.Response> findChatsByRoom(Long roomId, Pageable pageable);
+    ChatDto.Response createChat(ChatDto.SaveRequest saveRequestDto);
 }
diff --git a/src/main/java/com/sajang/devracebackend/service/UserRoomService.java b/src/main/java/com/sajang/devracebackend/service/UserRoomService.java
index b7dc026..8961712 100644
--- a/src/main/java/com/sajang/devracebackend/service/UserRoomService.java
+++ b/src/main/java/com/sajang/devracebackend/service/UserRoomService.java
@@ -9,10 +9,10 @@
 public interface UserRoomService {
     UserRoom findUserRoomWithEagerRoom(Long userId, Long roomId, boolean isIncludeUserRoomList, boolean isIncludeProblem);
     RoomDto.WaitResponse userWaitRoom(RoomDto.WaitRequest waitRequestDto);
-    void usersEnterRoom(Long roomId);
     void userStopWaitRoom(Long roomId);
-    UserRoomDto.SolvePageResponse loadSolvingPage(Long roomId);
-    UserRoomDto.CheckAccessResponse checkAccess(Long roomId);
-    void passSolvingProblem(Long roomId, UserRoomDto.SolveRequest solveRequest);
+    void usersEnterRoom(Long roomId);
+    void solveProblem(Long roomId, UserRoomDto.SolveRequest solveRequest);
+    UserRoomDto.SolvePageResponse loadSolvePage(Long roomId);
     Page<UserRoomDto.CodePageResponse> findCodeRooms(Integer isPass, Integer number, Pageable pageable);
+    UserRoomDto.CheckAccessResponse checkAccess(Long roomId);
 }
diff --git a/src/main/java/com/sajang/devracebackend/service/UserService.java b/src/main/java/com/sajang/devracebackend/service/UserService.java
index b2f2077..4af56ad 100644
--- a/src/main/java/com/sajang/devracebackend/service/UserService.java
+++ b/src/main/java/com/sajang/devracebackend/service/UserService.java
@@ -13,6 +13,6 @@ public interface UserService {
     <T> List<T> findUsersOriginal(List<Long> userIdList, boolean isDto);
     UserDto.Response findUserProfile();
     void updateUserProfile(MultipartFile imageFile, UserDto.UpdateRequest updateRequestDto) throws IOException;
-    UserDto.SolvedCountResponse checkUserSolvedCount();
-    UserDto.CheckRoomResponse checkCurrentRoom();
+    UserDto.SolvedCountResponse findUserSolvedCount();
+    UserDto.CheckRoomResponse checkRoom();
 }
\ No newline at end of file
diff --git a/src/main/java/com/sajang/devracebackend/service/impl/AuthServiceImpl.java b/src/main/java/com/sajang/devracebackend/service/impl/AuthServiceImpl.java
index 2d1fed8..69891b1 100644
--- a/src/main/java/com/sajang/devracebackend/service/impl/AuthServiceImpl.java
+++ b/src/main/java/com/sajang/devracebackend/service/impl/AuthServiceImpl.java
@@ -7,7 +7,6 @@
 import com.sajang.devracebackend.dto.UserDto;
 import com.sajang.devracebackend.repository.UserRepository;
 import com.sajang.devracebackend.repository.UserRoomBatchRepository;
-import com.sajang.devracebackend.repository.UserRoomRepository;
 import com.sajang.devracebackend.response.exception.Exception400;
 import com.sajang.devracebackend.security.jwt.TokenProvider;
 import com.sajang.devracebackend.service.AuthService;
@@ -30,7 +29,6 @@ public class AuthServiceImpl implements AuthService {
     private final AwsS3Service awsS3Service;
     private final UserService userService;
     private final UserRepository userRepository;
-    private final UserRoomRepository userRoomRepository;
     private final UserRoomBatchRepository userRoomBatchRepository;
     private final TokenProvider tokenProvider;
 
@@ -86,6 +84,23 @@ else if(imageFile == null && signupRequestDto.getIsImageChange() == 1) {  // 기
         return signupResponseDto;
     }
 
+    @Transactional
+    @Override
+    public void withdrawal() {
+        User user = userService.findLoginUser();
+        List<UserRoom> userRoomList = user.getUserRoomList();
+
+        // 자식 UserRoom 삭제 - hard delete
+        // userRoomRepository.deleteAll(userRoomList);  // JPA의 deleteAll()은 SQL 쿼리가 UserRoom 개수만큼 날아가는 문제가 있음.
+        // userRoomRepository.deleteAllInBatch(userRoomList);  // JPA의 deleteAllInBatch()은 10000개 이상의 데이터 처리시 stackoverflow 에러가 발생함.
+        userRoomBatchRepository.batchDelete(userRoomList);  // JDBC의 batch delete를 활용하여, 대용량 Batch 삭제 처리가 가능함. -> DB 여러번 접근 방지 & 성능 향상
+
+        // 부모 User 삭제 - soft delete
+        user.deleteAccount();
+        awsS3Service.deleteImage(user.getImageUrl());  // 이전의 사진은 AWS S3에서 삭제.
+        user.updateImage(null);  // 탈퇴했기에 기본사진임을 명시하고자 null값으로 imageUrl 업데이트.
+    }
+
     @Transactional
     @Override
     public AuthDto.TokenResponse reissue(AuthDto.ReissueRequest reissueRequestDto) {  // Refresh Token으로 Access Token 재발급 메소드
@@ -115,21 +130,4 @@ public AuthDto.TokenResponse reissue(AuthDto.ReissueRequest reissueRequestDto) {
         AuthDto.TokenResponse tokenResponseDto = tokenProvider.generateAccessTokenByRefreshToken(userId, role, refreshToken);
         return tokenResponseDto;
     }
-
-    @Transactional
-    @Override
-    public void withdrawal() {
-        User user = userService.findLoginUser();
-        List<UserRoom> userRoomList = user.getUserRoomList();
-
-        // 자식 UserRoom 삭제 - hard delete
-        // userRoomRepository.deleteAll(userRoomList);  // JPA의 deleteAll()은 SQL 쿼리가 UserRoom 개수만큼 날아가는 문제가 있음.
-        // userRoomRepository.deleteAllInBatch(userRoomList);  // JPA의 deleteAllInBatch()은 10000개 이상의 데이터 처리시 stackoverflow 에러가 발생함.
-        userRoomBatchRepository.batchDelete(userRoomList);  // JDBC의 batch delete를 활용하여, 대용량 Batch 삭제 처리가 가능함. -> DB 여러번 접근 방지 & 성능 향상
-
-        // 부모 User 삭제 - soft delete
-        user.deleteAccount();
-        awsS3Service.deleteImage(user.getImageUrl());  // 이전의 사진은 AWS S3에서 삭제.
-        user.updateImage(null);  // 탈퇴했기에 기본사진임을 명시하고자 null값으로 imageUrl 업데이트.
-    }
 }
diff --git a/src/main/java/com/sajang/devracebackend/service/impl/ChatServiceImpl.java b/src/main/java/com/sajang/devracebackend/service/impl/ChatServiceImpl.java
index d877bc8..520e286 100644
--- a/src/main/java/com/sajang/devracebackend/service/impl/ChatServiceImpl.java
+++ b/src/main/java/com/sajang/devracebackend/service/impl/ChatServiceImpl.java
@@ -36,6 +36,40 @@ public class ChatServiceImpl implements ChatService {
     private final ChatRepository chatRepository;
 
 
+    @Transactional(readOnly = true)
+    @Override
+    public Slice<ChatDto.Response> findChatsByRoom(Long roomId, Pageable pageable) {
+        // < 채팅방 페이징 정렬 기준 >
+        // - 페이징을 할 때, 최신 날짜인 마지막 페이지를 0으로 설정하여 역순으로 페이징.
+        // - 한 페이지 내의 채팅은 날짜 오름차순으로 정렬.
+        // - 만약 퇴장한 경우에는, 본인 퇴장시각 이하까지의 채팅 내역을 조회.
+        // => 알고리즘: DESC로 DB에서 페이징 조회후, 각 페이지별로 날짜 오름차순 정렬.
+
+        // 'UserRoom.room' Eager 로딩 (N+1 문제 해결)
+        UserRoom userRoom = userRoomService.findUserRoomWithEagerRoom(SecurityUtil.getCurrentMemberId(), roomId, false, false);
+        LocalDateTime leaveTime = userRoom.getLeaveTime();
+
+        // 퇴장한 경우, 본인 퇴장시각 이하까지의 채팅내역 페이징 조회
+        Slice<Chat> chatSlice;
+        if(userRoom.getIsLeave() == 1) chatSlice = chatRepository.findAllByRoomIdAndCreatedTimeLessThanEqual(roomId, leaveTime, pageable);
+        else chatSlice = chatRepository.findAllByRoomId(roomId, pageable);
+
+        // DESC로 가져온 데이터를 다시 오름차순으로 페이지별 정렬
+        List<Chat> reversedChatList = new ArrayList<>(chatSlice.getContent());  // 새로운 리스트로 만듦으로써 불변성 해제.
+        Collections.reverse(reversedChatList);
+
+        // 사용자 캐싱을 위한 맵 생성 (이미 검색한것은 다시 검색하지않도록 성능 향상)
+        Map<Long, User> cacheUserMap = new HashMap<>();
+
+        return new SliceImpl<>(reversedChatList.stream()
+                .map(chat -> {
+                    Long senderId = chat.getSenderId();
+                    User senderUser = cacheUserMap.computeIfAbsent(senderId, id -> userService.findUser(id));  // 만약 캐시에 senderId키의 데이터가 없다면, DB조회하고 캐시에 추가.
+                    return new ChatDto.Response(chat, senderUser.getNickname(), senderUser.getImageUrl());
+                })
+                .collect(Collectors.toList()), pageable, chatSlice.hasNext());
+    }
+
     @Transactional
     @Override
     public ChatDto.Response createChat(ChatDto.SaveRequest saveRequestDto) {
@@ -77,38 +111,4 @@ else if(saveRequestDto.getMessageType().equals(MessageType.RANK)) {
 
         return new ChatDto.Response(chat, user.getNickname(), user.getImageUrl());
     }
-
-    @Transactional(readOnly = true)
-    @Override
-    public Slice<ChatDto.Response> findChatsByRoom(Long roomId, Pageable pageable) {
-        // < 채팅방 페이징 정렬 기준 >
-        // - 페이징을 할 때, 최신 날짜인 마지막 페이지를 0으로 설정하여 역순으로 페이징.
-        // - 한 페이지 내의 채팅은 날짜 오름차순으로 정렬.
-        // - 만약 퇴장한 경우에는, 본인 퇴장시각 이하까지의 채팅 내역을 조회.
-        // => 알고리즘: DESC로 DB에서 페이징 조회후, 각 페이지별로 날짜 오름차순 정렬.
-
-        // 'UserRoom.room' Eager 로딩 (N+1 문제 해결)
-        UserRoom userRoom = userRoomService.findUserRoomWithEagerRoom(SecurityUtil.getCurrentMemberId(), roomId, false, false);
-        LocalDateTime leaveTime = userRoom.getLeaveTime();
-
-        // 퇴장한 경우, 본인 퇴장시각 이하까지의 채팅내역 페이징 조회
-        Slice<Chat> chatSlice;
-        if(userRoom.getIsLeave() == 1) chatSlice = chatRepository.findAllByRoomIdAndCreatedTimeLessThanEqual(roomId, leaveTime, pageable);
-        else chatSlice = chatRepository.findAllByRoomId(roomId, pageable);
-
-        // DESC로 가져온 데이터를 다시 오름차순으로 페이지별 정렬
-        List<Chat> reversedChatList = new ArrayList<>(chatSlice.getContent());  // 새로운 리스트로 만듦으로써 불변성 해제.
-        Collections.reverse(reversedChatList);
-
-        // 사용자 캐싱을 위한 맵 생성 (이미 검색한것은 다시 검색하지않도록 성능 향상)
-        Map<Long, User> cacheUserMap = new HashMap<>();
-
-        return new SliceImpl<>(reversedChatList.stream()
-                .map(chat -> {
-                    Long senderId = chat.getSenderId();
-                    User senderUser = cacheUserMap.computeIfAbsent(senderId, id -> userService.findUser(id));  // 만약 캐시에 senderId키의 데이터가 없다면, DB조회하고 캐시에 추가.
-                    return new ChatDto.Response(chat, senderUser.getNickname(), senderUser.getImageUrl());
-                })
-                .collect(Collectors.toList()), pageable, chatSlice.hasNext());
-    }
 }
diff --git a/src/main/java/com/sajang/devracebackend/service/impl/UserRoomServiceImpl.java b/src/main/java/com/sajang/devracebackend/service/impl/UserRoomServiceImpl.java
index 1037453..38b0b31 100644
--- a/src/main/java/com/sajang/devracebackend/service/impl/UserRoomServiceImpl.java
+++ b/src/main/java/com/sajang/devracebackend/service/impl/UserRoomServiceImpl.java
@@ -90,6 +90,13 @@ public RoomDto.WaitResponse userWaitRoom(RoomDto.WaitRequest waitRequestDto) {
         return waitResponseDto;
     }
 
+    @Transactional
+    @Override
+    public void userStopWaitRoom(Long roomId) {
+        Room room = roomService.findRoom(roomId);
+        room.deleteWaiting(SecurityUtil.getCurrentMemberId(), false);  // 대기자 목록에서 해당 사용자 제거.
+    }
+
     @Transactional
     @Override
     public void usersEnterRoom(Long roomId) {
@@ -133,51 +140,7 @@ public void usersEnterRoom(Long roomId) {
 
     @Transactional
     @Override
-    public void userStopWaitRoom(Long roomId) {
-        Room room = roomService.findRoom(roomId);
-        room.deleteWaiting(SecurityUtil.getCurrentMemberId(), false);  // 대기자 목록에서 해당 사용자 제거.
-    }
-
-    @Transactional(readOnly = true)
-    @Override
-    public UserRoomDto.SolvePageResponse loadSolvingPage(Long roomId) {
-
-        // 'UserRoom.room & UserRoom.room.problem' Eager 로딩 (N+1 문제 해결)
-        UserRoom userRoom = findUserRoomWithEagerRoom(SecurityUtil.getCurrentMemberId(), roomId, false, true);  // 어차피 문제풀이 페이지는 입장 이후이기에, 부모 Room을 갖고있는 자식 UserRoom은 반드시 존재함.
-
-        List<Long> rankUserIdList = userRoom.getRoom().getWaiting();
-        List<UserDto.Response> rankUserDtoList = userService.findUsersOriginal(rankUserIdList, true);
-
-        return new UserRoomDto.SolvePageResponse(userRoom, rankUserDtoList);  // Fetch Join으로 UserRoom 내부의 UserRoom.room과 UserRoom.room.problem은 Eager 로딩 처리되어, N+1 문제가 발생하지 않음.
-    }
-
-    @Transactional(readOnly = true)
-    @Override
-    public UserRoomDto.CheckAccessResponse checkAccess(Long roomId) {
-
-        // 'UserRoom.room' Eager 로딩 (N+1 문제 해결)
-        Optional<UserRoom> optionalUserRoom = userRoomRepository.findByUser_IdAndRoom_Id(SecurityUtil.getCurrentMemberId(), roomId);
-
-        // UserRoom이 존재하면 해당 정보 사용. 그렇지 않다면 DB에 Room 조회 쿼리 날림.
-        Room room = optionalUserRoom
-                .map(UserRoom::getRoom)  // 이 시점에는 아직 @EntityGraph의 영향을 받지않아, 아직 조회 쿼리가 1번으로 유지됨.
-                .orElseGet(() -> roomService.findRoom(roomId));
-
-        Boolean isExistUserRoom = optionalUserRoom.isPresent();
-        Integer isLeave = optionalUserRoom.map(UserRoom::getIsLeave).orElse(null);  // UserRoom이 없다면 isLeave는 null
-
-        UserRoomDto.CheckAccessResponse checkAccessResponseDto = UserRoomDto.CheckAccessResponse.builder()
-                .isExistUserRoom(isExistUserRoom)
-                .roomState(room.getRoomState())  // @EntityGraph로 UserRoom 내부의 Room은 Eager 로딩 처리되어, N+1 문제가 발생하지 않음.
-                .isLeave(isLeave)
-                .build();
-
-        return checkAccessResponseDto;
-    }
-
-    @Transactional
-    @Override
-    public void passSolvingProblem(Long roomId, UserRoomDto.SolveRequest solveRequestDto) {
+    public void solveProblem(Long roomId, UserRoomDto.SolveRequest solveRequestDto) {
 
         // 'UserRoom.room & UserRoom.userRoomList' Eager 로딩 (N+1 문제 해결)
         UserRoom userRoom = findUserRoomWithEagerRoom(SecurityUtil.getCurrentMemberId(), roomId, true, false);  // 어차피 문제풀이 페이지는 입장 이후이기에, 부모 Room을 갖고있는 자식 UserRoom은 반드시 존재함.
@@ -198,6 +161,19 @@ public void passSolvingProblem(Long roomId, UserRoomDto.SolveRequest solveReques
         if(isLeaveAllUsers == true) room.updateRoomState(RoomState.FINISH);
     }
 
+    @Transactional(readOnly = true)
+    @Override
+    public UserRoomDto.SolvePageResponse loadSolvePage(Long roomId) {
+
+        // 'UserRoom.room & UserRoom.room.problem' Eager 로딩 (N+1 문제 해결)
+        UserRoom userRoom = findUserRoomWithEagerRoom(SecurityUtil.getCurrentMemberId(), roomId, false, true);  // 어차피 문제풀이 페이지는 입장 이후이기에, 부모 Room을 갖고있는 자식 UserRoom은 반드시 존재함.
+
+        List<Long> rankUserIdList = userRoom.getRoom().getWaiting();
+        List<UserDto.Response> rankUserDtoList = userService.findUsersOriginal(rankUserIdList, true);
+
+        return new UserRoomDto.SolvePageResponse(userRoom, rankUserDtoList);  // Fetch Join으로 UserRoom 내부의 UserRoom.room과 UserRoom.room.problem은 Eager 로딩 처리되어, N+1 문제가 발생하지 않음.
+    }
+
     @Transactional(readOnly = true)
     @Override
     public Page<UserRoomDto.CodePageResponse> findCodeRooms(Integer isPass, Integer number, Pageable pageable) {
@@ -221,6 +197,30 @@ else if(isPass == null && number != null) {  // 문제번호 검색 조회의 
         return userRoomPage.map(userRoom -> new UserRoomDto.CodePageResponse(userRoom));
     }
 
+    @Transactional(readOnly = true)
+    @Override
+    public UserRoomDto.CheckAccessResponse checkAccess(Long roomId) {
+
+        // 'UserRoom.room' Eager 로딩 (N+1 문제 해결)
+        Optional<UserRoom> optionalUserRoom = userRoomRepository.findByUser_IdAndRoom_Id(SecurityUtil.getCurrentMemberId(), roomId);
+
+        // UserRoom이 존재하면 해당 정보 사용. 그렇지 않다면 DB에 Room 조회 쿼리 날림.
+        Room room = optionalUserRoom
+                .map(UserRoom::getRoom)  // 이 시점에는 아직 @EntityGraph의 영향을 받지않아, 아직 조회 쿼리가 1번으로 유지됨.
+                .orElseGet(() -> roomService.findRoom(roomId));
+
+        Boolean isExistUserRoom = optionalUserRoom.isPresent();
+        Integer isLeave = optionalUserRoom.map(UserRoom::getIsLeave).orElse(null);  // UserRoom이 없다면 isLeave는 null
+
+        UserRoomDto.CheckAccessResponse checkAccessResponseDto = UserRoomDto.CheckAccessResponse.builder()
+                .isExistUserRoom(isExistUserRoom)
+                .roomState(room.getRoomState())  // @EntityGraph로 UserRoom 내부의 Room은 Eager 로딩 처리되어, N+1 문제가 발생하지 않음.
+                .isLeave(isLeave)
+                .build();
+
+        return checkAccessResponseDto;
+    }
+
 
     // ========== 유틸성 메소드 ========== //
 
diff --git a/src/main/java/com/sajang/devracebackend/service/impl/UserServiceImpl.java b/src/main/java/com/sajang/devracebackend/service/impl/UserServiceImpl.java
index 53a78d3..b34dc4f 100644
--- a/src/main/java/com/sajang/devracebackend/service/impl/UserServiceImpl.java
+++ b/src/main/java/com/sajang/devracebackend/service/impl/UserServiceImpl.java
@@ -91,7 +91,7 @@ else if(imageFile == null && updateRequestDto.getIsImageChange() == 1) {  // 기
 
     @Transactional(readOnly = true)
     @Override
-    public UserDto.SolvedCountResponse checkUserSolvedCount() {
+    public UserDto.SolvedCountResponse findUserSolvedCount() {
         User user = findLoginUser();
         UserDto.SolvedCountResponse solvedCountResponseDto = getSolvedCount(user.getBojId());
 
@@ -100,7 +100,7 @@ public UserDto.SolvedCountResponse checkUserSolvedCount() {
 
     @Transactional(readOnly = true)
     @Override
-    public UserDto.CheckRoomResponse checkCurrentRoom() {
+    public UserDto.CheckRoomResponse checkRoom() {
 
         // 'User.userRoomList' Eager 로딩 (N+1 문제 해결)
         User user = userRepository.findByIdWithEagerUserRoomList(SecurityUtil.getCurrentMemberId()).orElseThrow(