diff --git a/src/main/java/today/meevote/domain/voting_schedule/service/VotingScheduleService.java b/src/main/java/today/meevote/domain/voting_schedule/service/VotingScheduleService.java
index 9eb5283..ab5ecc7 100644
--- a/src/main/java/today/meevote/domain/voting_schedule/service/VotingScheduleService.java
+++ b/src/main/java/today/meevote/domain/voting_schedule/service/VotingScheduleService.java
@@ -1,6 +1,7 @@
 package today.meevote.domain.voting_schedule.service;
 
 import lombok.RequiredArgsConstructor;
+import org.springframework.dao.DuplicateKeyException;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 import today.meevote.contextholder.MemberContextHolder;
@@ -11,6 +12,7 @@
 import today.meevote.exception.rest.RestException;
 import today.meevote.response.FailureInfo;
 
+import java.sql.SQLException;
 import java.util.List;
 
 @Service
@@ -57,10 +59,13 @@ public void addPlaceToVote(long scheduleId, CreatePlaceDto addPlaceToVoteDto) {
         if(!votingScheduleDao.isExistMemberSchedule(email, scheduleId))
             throw new RestException(FailureInfo.NOT_EXIST_MEMBER_SCHEDULE);
 
-        if(votingScheduleDao.isDuplicatePlaceToVote(scheduleId, addPlaceToVoteDto))
+        // SQLException - 동시성 제어 / 유니크 키 제약 조건 위반 처리
+        try {
+            votingScheduleDao.addPlaceToVote(scheduleId, addPlaceToVoteDto);
+        } catch (DuplicateKeyException e) {
+            // ORA-00001: unique 키 위배
             throw new RestException(FailureInfo.ALREADY_EXIST_PLACE_TO_VOTE);
-
-        votingScheduleDao.addPlaceToVote(scheduleId, addPlaceToVoteDto);
+        }
     }
 
     public void toggleVotePlace(long placeToVoteId) {
diff --git a/src/main/java/today/meevote/response/FailureInfo.java b/src/main/java/today/meevote/response/FailureInfo.java
index d206ecb..3b4fc33 100644
--- a/src/main/java/today/meevote/response/FailureInfo.java
+++ b/src/main/java/today/meevote/response/FailureInfo.java
@@ -32,6 +32,7 @@ public enum FailureInfo {
     NOT_EXIST_SCHEDULE("S02", "존재하지 않는 일정입니다."),
     NOT_EXIST_DELETE_SCHEDULE("S03", "삭제가 불가능한 일정입니다. 확인 후 다시 시도해주세요."),
     NOT_OUT_MEMBER_SCHEDULE("S04", "나가기가 불가능한 일정입니다. 확인 후 다시 시도해주세요."),
+    ALREADY_EXIST_GROUP_MEMBER("S05", "이미 존재하는 그룹일정입니다."),
     NOT_SCHEDULE_OWNER("S98", "해당 일정의 소유자가 아닙니다."),
     NOT_EXIST_MEMBER_SCHEDULE("S99", "해당 일정의 멤버가 아닙니다."),
 
diff --git a/src/main/resources/mapper/notifyMapper.xml b/src/main/resources/mapper/notifyMapper.xml
index 7fd8a3d..0fc6df9 100644
--- a/src/main/resources/mapper/notifyMapper.xml
+++ b/src/main/resources/mapper/notifyMapper.xml
@@ -35,6 +35,7 @@
             LEFT JOIN schedule_place sp ON n.schedule_id = sp.schedule_id
         WHERE
             n.email = #{email}
+            AND n.is_read = 0
         ORDER BY n.is_read ASC, n.notify_id DESC
     </select>
 
diff --git a/src/main/resources/sql/sql_0515 b/src/main/resources/sql/sql_0515
new file mode 100644
index 0000000..12f47ec
--- /dev/null
+++ b/src/main/resources/sql/sql_0515
@@ -0,0 +1,12 @@
+-- 컬럼 길이 줄이기
+ALTER TABLE place_to_vote MODIFY place_name NVARCHAR2(1000);
+ALTER TABLE place_to_vote MODIFY lat NVARCHAR2(1000);
+ALTER TABLE place_to_vote MODIFY lng NVARCHAR2(1000);
+
+-- 복합 유니크 인덱스 생성
+CREATE UNIQUE INDEX uq_place_to_vote
+ON place_to_vote (schedule_id, lat, lng);
+
+-- place_to_vote 테이블에 새로운 유니크 제약 조건을 추가
+ALTER TABLE place_to_vote
+ADD CONSTRAINT uq_place_to_vote UNIQUE (schedule_id, lat, lng);
\ No newline at end of file