diff --git a/src/main/java/in/koreatech/koin/domain/user/dto/StudentRegisterRequest.java b/src/main/java/in/koreatech/koin/domain/user/dto/StudentRegisterRequest.java
index eec39acc97..f7cf42420e 100644
--- a/src/main/java/in/koreatech/koin/domain/user/dto/StudentRegisterRequest.java
+++ b/src/main/java/in/koreatech/koin/domain/user/dto/StudentRegisterRequest.java
@@ -71,7 +71,7 @@ public Student toStudent(PasswordEncoder passwordEncoder, Clock clock) {
             .isDeleted(false)
             .userType(UserType.STUDENT)
             .authToken(UUID.randomUUID().toString())
-            .authExpiredAt(LocalDateTime.now(clock).plusHours(1))
+            .authExpiredAt(LocalDateTime.now(clock).plusHours(10))
             .build();
 
         return Student.builder()
diff --git a/src/main/java/in/koreatech/koin/global/config/LocalDateTimeAttributeConverter.java b/src/main/java/in/koreatech/koin/global/config/LocalDateTimeAttributeConverter.java
index d9c36be94f..f38c3320c4 100644
--- a/src/main/java/in/koreatech/koin/global/config/LocalDateTimeAttributeConverter.java
+++ b/src/main/java/in/koreatech/koin/global/config/LocalDateTimeAttributeConverter.java
@@ -9,14 +9,15 @@
 @Converter(autoApply = true)
 public class LocalDateTimeAttributeConverter implements AttributeConverter<LocalDateTime, String> {
 
-    private final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss[.SSS]");
+    private final DateTimeFormatter formatterWithThreeMillis = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss[.SSS]");
+    private final DateTimeFormatter formatterWithTwoMillis = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SS");
 
     @Override
     public String convertToDatabaseColumn(LocalDateTime localDateTime) {
         if (localDateTime == null) {
             return null;
         }
-        return localDateTime.format(formatter);
+        return localDateTime.format(formatterWithThreeMillis);
     }
 
     @Override
@@ -24,7 +25,11 @@ public LocalDateTime convertToEntityAttribute(String dbData) {
         if (dbData == null) {
             return null;
         }
-        return LocalDateTime.parse(dbData, formatter);
+
+        if (dbData.matches(".*\\.\\d{3}$")) {
+            return LocalDateTime.parse(dbData, formatterWithThreeMillis);
+        } else {
+            return LocalDateTime.parse(dbData, formatterWithTwoMillis);
+        }
     }
 }
-