diff --git a/src/main/kotlin/com/wafflestudio/csereal/common/controller/AttachmentContentEntityType.kt b/src/main/kotlin/com/wafflestudio/csereal/common/controller/AttachmentContentEntityType.kt
deleted file mode 100644
index 6972e8e7..00000000
--- a/src/main/kotlin/com/wafflestudio/csereal/common/controller/AttachmentContentEntityType.kt
+++ /dev/null
@@ -1,7 +0,0 @@
-package com.wafflestudio.csereal.common.controller
-
-import com.wafflestudio.csereal.core.resource.attachment.database.AttachmentEntity
-
-interface AttachmentContentEntityType {
-    fun bringAttachments(): List<AttachmentEntity>
-}
diff --git a/src/main/kotlin/com/wafflestudio/csereal/common/controller/MainImageContentEntityType.kt b/src/main/kotlin/com/wafflestudio/csereal/common/controller/MainImageContentEntityType.kt
deleted file mode 100644
index 0923842a..00000000
--- a/src/main/kotlin/com/wafflestudio/csereal/common/controller/MainImageContentEntityType.kt
+++ /dev/null
@@ -1,7 +0,0 @@
-package com.wafflestudio.csereal.common.controller
-
-import com.wafflestudio.csereal.core.resource.mainImage.database.MainImageEntity
-
-interface MainImageContentEntityType {
-    fun bringMainImage(): MainImageEntity?
-}
diff --git a/src/main/kotlin/com/wafflestudio/csereal/common/entity/AttachmentAttachable.kt b/src/main/kotlin/com/wafflestudio/csereal/common/entity/AttachmentAttachable.kt
new file mode 100644
index 00000000..0b92c6e0
--- /dev/null
+++ b/src/main/kotlin/com/wafflestudio/csereal/common/entity/AttachmentAttachable.kt
@@ -0,0 +1,7 @@
+package com.wafflestudio.csereal.common.entity
+
+import com.wafflestudio.csereal.core.resource.attachment.database.AttachmentEntity
+
+interface AttachmentAttachable {
+    val attachments: List<AttachmentEntity>
+}
diff --git a/src/main/kotlin/com/wafflestudio/csereal/common/entity/MainImageAttachable.kt b/src/main/kotlin/com/wafflestudio/csereal/common/entity/MainImageAttachable.kt
new file mode 100644
index 00000000..6c23ea29
--- /dev/null
+++ b/src/main/kotlin/com/wafflestudio/csereal/common/entity/MainImageAttachable.kt
@@ -0,0 +1,7 @@
+package com.wafflestudio.csereal.common.entity
+
+import com.wafflestudio.csereal.core.resource.mainImage.database.MainImageEntity
+
+interface MainImageAttachable {
+    val mainImage: MainImageEntity?
+}
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/about/database/AboutEntity.kt b/src/main/kotlin/com/wafflestudio/csereal/core/about/database/AboutEntity.kt
index 9220090c..625f6086 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/about/database/AboutEntity.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/about/database/AboutEntity.kt
@@ -1,8 +1,8 @@
 package com.wafflestudio.csereal.core.about.database
 
 import com.wafflestudio.csereal.common.entity.BaseTimeEntity
-import com.wafflestudio.csereal.common.controller.AttachmentContentEntityType
-import com.wafflestudio.csereal.common.controller.MainImageContentEntityType
+import com.wafflestudio.csereal.common.entity.AttachmentAttachable
+import com.wafflestudio.csereal.common.entity.MainImageAttachable
 import com.wafflestudio.csereal.common.enums.LanguageType
 import com.wafflestudio.csereal.common.utils.StringListConverter
 import com.wafflestudio.csereal.common.utils.cleanTextFromHtml
@@ -27,17 +27,15 @@ class AboutEntity(
     var locations: MutableList<String> = mutableListOf(),
 
     @OneToMany(mappedBy = "about", cascade = [CascadeType.ALL], orphanRemoval = true)
-    var attachments: MutableList<AttachmentEntity> = mutableListOf(),
+    override var attachments: MutableList<AttachmentEntity> = mutableListOf(),
 
     @OneToOne(fetch = FetchType.LAZY, cascade = [CascadeType.ALL], orphanRemoval = true)
-    var mainImage: MainImageEntity? = null,
+    override var mainImage: MainImageEntity? = null,
 
     @Column(columnDefinition = "TEXT")
     var searchContent: String
 
-) : BaseTimeEntity(), MainImageContentEntityType, AttachmentContentEntityType {
-    override fun bringMainImage(): MainImageEntity? = mainImage
-    override fun bringAttachments(): List<AttachmentEntity> = attachments
+) : BaseTimeEntity(), MainImageAttachable, AttachmentAttachable {
 
     companion object {
         fun of(
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/academics/database/AcademicsEntity.kt b/src/main/kotlin/com/wafflestudio/csereal/core/academics/database/AcademicsEntity.kt
index 5515102a..0f306d66 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/academics/database/AcademicsEntity.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/academics/database/AcademicsEntity.kt
@@ -1,7 +1,7 @@
 package com.wafflestudio.csereal.core.academics.database
 
 import com.wafflestudio.csereal.common.entity.BaseTimeEntity
-import com.wafflestudio.csereal.common.controller.AttachmentContentEntityType
+import com.wafflestudio.csereal.common.entity.AttachmentAttachable
 import com.wafflestudio.csereal.common.enums.LanguageType
 import com.wafflestudio.csereal.core.academics.api.req.CreateYearReq
 import com.wafflestudio.csereal.core.resource.attachment.database.AttachmentEntity
@@ -24,13 +24,12 @@ class AcademicsEntity(
     var year: Int?,
 
     @OneToMany(mappedBy = "academics", cascade = [CascadeType.ALL], orphanRemoval = true)
-    var attachments: MutableList<AttachmentEntity> = mutableListOf(),
+    override var attachments: MutableList<AttachmentEntity> = mutableListOf(),
 
     @OneToOne(mappedBy = "academics", cascade = [CascadeType.ALL], orphanRemoval = true)
     var academicsSearch: AcademicsSearchEntity? = null
 
-) : BaseTimeEntity(), AttachmentContentEntityType {
-    override fun bringAttachments() = attachments
+) : BaseTimeEntity(), AttachmentAttachable {
 
     companion object {
         fun createYearResponse(
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/council/database/CouncilEntity.kt b/src/main/kotlin/com/wafflestudio/csereal/core/council/database/CouncilEntity.kt
index d0d8c275..0ff8d47e 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/council/database/CouncilEntity.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/council/database/CouncilEntity.kt
@@ -1,7 +1,7 @@
 package com.wafflestudio.csereal.core.council.database
 
 import com.wafflestudio.csereal.common.entity.BaseTimeEntity
-import com.wafflestudio.csereal.common.controller.MainImageContentEntityType
+import com.wafflestudio.csereal.common.entity.MainImageAttachable
 import com.wafflestudio.csereal.core.council.dto.ReportCreateRequest
 import com.wafflestudio.csereal.core.resource.mainImage.database.MainImageEntity
 import jakarta.persistence.*
@@ -17,12 +17,11 @@ class CouncilEntity(
     var description: String,
 
     @OneToOne
-    var mainImage: MainImageEntity? = null,
+    override var mainImage: MainImageEntity? = null,
 
     var sequence: Int,
     var name: String
-) : BaseTimeEntity(), MainImageContentEntityType {
-    override fun bringMainImage() = mainImage
+) : BaseTimeEntity(), MainImageAttachable {
 
     companion object {
         fun createReport(req: ReportCreateRequest): CouncilEntity =
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/council/database/CouncilFileEntity.kt b/src/main/kotlin/com/wafflestudio/csereal/core/council/database/CouncilFileEntity.kt
index 4d405d5e..a442f187 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/council/database/CouncilFileEntity.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/council/database/CouncilFileEntity.kt
@@ -1,7 +1,7 @@
 package com.wafflestudio.csereal.core.council.database
 
 import com.wafflestudio.csereal.common.entity.BaseTimeEntity
-import com.wafflestudio.csereal.common.controller.AttachmentContentEntityType
+import com.wafflestudio.csereal.common.entity.AttachmentAttachable
 import com.wafflestudio.csereal.core.council.type.CouncilFileType
 import com.wafflestudio.csereal.core.resource.attachment.database.AttachmentEntity
 import jakarta.persistence.*
@@ -20,7 +20,5 @@ class CouncilFileEntity(
     val key: String,
 
     @OneToMany(mappedBy = "councilFile", cascade = [CascadeType.ALL], orphanRemoval = true)
-    val attachments: MutableList<AttachmentEntity> = mutableListOf()
-) : BaseTimeEntity(), AttachmentContentEntityType {
-    override fun bringAttachments(): List<AttachmentEntity> = attachments
-}
+    override val attachments: MutableList<AttachmentEntity> = mutableListOf()
+) : BaseTimeEntity(), AttachmentAttachable
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/member/database/ProfessorEntity.kt b/src/main/kotlin/com/wafflestudio/csereal/core/member/database/ProfessorEntity.kt
index a2a938ba..521f46bc 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/member/database/ProfessorEntity.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/member/database/ProfessorEntity.kt
@@ -1,7 +1,7 @@
 package com.wafflestudio.csereal.core.member.database
 
 import com.wafflestudio.csereal.common.entity.BaseTimeEntity
-import com.wafflestudio.csereal.common.controller.MainImageContentEntityType
+import com.wafflestudio.csereal.common.entity.MainImageAttachable
 import com.wafflestudio.csereal.common.enums.LanguageType
 import com.wafflestudio.csereal.common.utils.StringListConverter
 import com.wafflestudio.csereal.core.member.dto.ProfessorDto
@@ -48,12 +48,11 @@ class ProfessorEntity(
     var careers: MutableList<String> = mutableListOf(),
 
     @OneToOne
-    var mainImage: MainImageEntity? = null,
+    override var mainImage: MainImageEntity? = null,
 
     @OneToOne(mappedBy = "professor", cascade = [CascadeType.ALL], orphanRemoval = true)
     var memberSearch: MemberSearchEntity? = null
-) : BaseTimeEntity(), MainImageContentEntityType {
-    override fun bringMainImage(): MainImageEntity? = mainImage
+) : BaseTimeEntity(), MainImageAttachable {
 
     companion object {
         fun of(languageType: LanguageType, professorDto: ProfessorDto): ProfessorEntity {
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/member/database/StaffEntity.kt b/src/main/kotlin/com/wafflestudio/csereal/core/member/database/StaffEntity.kt
index 0436b182..a7c0d558 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/member/database/StaffEntity.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/member/database/StaffEntity.kt
@@ -1,7 +1,7 @@
 package com.wafflestudio.csereal.core.member.database
 
 import com.wafflestudio.csereal.common.entity.BaseTimeEntity
-import com.wafflestudio.csereal.common.controller.MainImageContentEntityType
+import com.wafflestudio.csereal.common.entity.MainImageAttachable
 import com.wafflestudio.csereal.common.enums.LanguageType
 import com.wafflestudio.csereal.common.utils.StringListConverter
 import com.wafflestudio.csereal.core.member.dto.StaffDto
@@ -25,12 +25,11 @@ class StaffEntity(
     var tasks: MutableList<String> = mutableListOf(),
 
     @OneToOne
-    var mainImage: MainImageEntity? = null,
+    override var mainImage: MainImageEntity? = null,
 
     @OneToOne(mappedBy = "staff", cascade = [CascadeType.ALL], orphanRemoval = true)
     var memberSearch: MemberSearchEntity? = null
-) : BaseTimeEntity(), MainImageContentEntityType {
-    override fun bringMainImage(): MainImageEntity? = mainImage
+) : BaseTimeEntity(), MainImageAttachable {
 
     companion object {
         fun of(languageType: LanguageType, staffDto: StaffDto): StaffEntity {
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/news/database/NewsEntity.kt b/src/main/kotlin/com/wafflestudio/csereal/core/news/database/NewsEntity.kt
index 34c122f0..c6a3b7b0 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/news/database/NewsEntity.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/news/database/NewsEntity.kt
@@ -1,8 +1,8 @@
 package com.wafflestudio.csereal.core.news.database
 
 import com.wafflestudio.csereal.common.entity.BaseTimeEntity
-import com.wafflestudio.csereal.common.controller.AttachmentContentEntityType
-import com.wafflestudio.csereal.common.controller.MainImageContentEntityType
+import com.wafflestudio.csereal.common.entity.AttachmentAttachable
+import com.wafflestudio.csereal.common.entity.MainImageAttachable
 import com.wafflestudio.csereal.common.utils.cleanTextFromHtml
 import com.wafflestudio.csereal.core.news.dto.NewsDto
 import com.wafflestudio.csereal.core.resource.attachment.database.AttachmentEntity
@@ -31,17 +31,15 @@ class NewsEntity(
     var importantUntil: LocalDate? = null,
 
     @OneToOne
-    var mainImage: MainImageEntity? = null,
+    override var mainImage: MainImageEntity? = null,
 
     @OneToMany(mappedBy = "news", cascade = [CascadeType.ALL], orphanRemoval = true)
-    var attachments: MutableList<AttachmentEntity> = mutableListOf(),
+    override var attachments: MutableList<AttachmentEntity> = mutableListOf(),
 
     @OneToMany(mappedBy = "news", cascade = [CascadeType.ALL])
     var newsTags: MutableSet<NewsTagEntity> = mutableSetOf()
 
-) : BaseTimeEntity(), MainImageContentEntityType, AttachmentContentEntityType {
-    override fun bringMainImage() = mainImage
-    override fun bringAttachments() = attachments
+) : BaseTimeEntity(), MainImageAttachable, AttachmentAttachable {
 
     companion object {
         fun of(newsDto: NewsDto): NewsEntity {
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/notice/database/NoticeEntity.kt b/src/main/kotlin/com/wafflestudio/csereal/core/notice/database/NoticeEntity.kt
index c4839742..5bc559b9 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/notice/database/NoticeEntity.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/notice/database/NoticeEntity.kt
@@ -2,7 +2,7 @@ package com.wafflestudio.csereal.core.notice.database
 
 import com.wafflestudio.csereal.common.utils.cleanTextFromHtml
 import com.wafflestudio.csereal.common.entity.BaseTimeEntity
-import com.wafflestudio.csereal.common.controller.AttachmentContentEntityType
+import com.wafflestudio.csereal.common.entity.AttachmentAttachable
 import com.wafflestudio.csereal.core.notice.dto.NoticeDto
 import com.wafflestudio.csereal.core.resource.attachment.database.AttachmentEntity
 import com.wafflestudio.csereal.core.user.database.UserEntity
@@ -38,10 +38,9 @@ class NoticeEntity(
     val author: UserEntity,
 
     @OneToMany(mappedBy = "notice", cascade = [CascadeType.ALL], orphanRemoval = true)
-    var attachments: MutableList<AttachmentEntity> = mutableListOf()
+    override var attachments: MutableList<AttachmentEntity> = mutableListOf()
 
-) : BaseTimeEntity(), AttachmentContentEntityType {
-    override fun bringAttachments() = attachments
+) : BaseTimeEntity(), AttachmentAttachable {
 
     fun update(updateNoticeRequest: NoticeDto) {
         // Update plainTextDescription if description is changed
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/recruit/database/RecruitEntity.kt b/src/main/kotlin/com/wafflestudio/csereal/core/recruit/database/RecruitEntity.kt
index 980090c2..e897aa86 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/recruit/database/RecruitEntity.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/recruit/database/RecruitEntity.kt
@@ -1,7 +1,7 @@
 package com.wafflestudio.csereal.core.recruit.database
 
 import com.wafflestudio.csereal.common.entity.BaseTimeEntity
-import com.wafflestudio.csereal.common.controller.MainImageContentEntityType
+import com.wafflestudio.csereal.common.entity.MainImageAttachable
 import com.wafflestudio.csereal.core.resource.mainImage.database.MainImageEntity
 import jakarta.persistence.Column
 import jakarta.persistence.Entity
@@ -15,7 +15,5 @@ class RecruitEntity(
     var description: String,
 
     @OneToOne
-    var mainImage: MainImageEntity? = null
-) : BaseTimeEntity(), MainImageContentEntityType {
-    override fun bringMainImage(): MainImageEntity? = mainImage
-}
+    override var mainImage: MainImageEntity? = null
+) : BaseTimeEntity(), MainImageAttachable
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/research/database/ResearchEntity.kt b/src/main/kotlin/com/wafflestudio/csereal/core/research/database/ResearchEntity.kt
index 7437592f..9ed4409f 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/research/database/ResearchEntity.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/research/database/ResearchEntity.kt
@@ -1,7 +1,7 @@
 package com.wafflestudio.csereal.core.research.database
 
 import com.wafflestudio.csereal.common.entity.BaseTimeEntity
-import com.wafflestudio.csereal.common.controller.MainImageContentEntityType
+import com.wafflestudio.csereal.common.entity.MainImageAttachable
 import com.wafflestudio.csereal.common.enums.LanguageType
 import com.wafflestudio.csereal.core.research.dto.ResearchDto
 import com.wafflestudio.csereal.core.research.type.ResearchType
@@ -27,12 +27,11 @@ class ResearchEntity(
     var labs: MutableSet<LabEntity> = mutableSetOf(),
 
     @OneToOne
-    var mainImage: MainImageEntity? = null,
+    override var mainImage: MainImageEntity? = null,
 
     @OneToOne(mappedBy = "research", cascade = [CascadeType.ALL], orphanRemoval = true)
     var researchSearch: ResearchSearchEntity? = null
-) : BaseTimeEntity(), MainImageContentEntityType {
-    override fun bringMainImage() = mainImage
+) : BaseTimeEntity(), MainImageAttachable {
 
     companion object {
         fun of(languageType: LanguageType, researchDto: ResearchDto): ResearchEntity {
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/resource/attachment/service/AttachmentService.kt b/src/main/kotlin/com/wafflestudio/csereal/core/resource/attachment/service/AttachmentService.kt
index d40dc567..b51d0d37 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/resource/attachment/service/AttachmentService.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/resource/attachment/service/AttachmentService.kt
@@ -1,7 +1,7 @@
 package com.wafflestudio.csereal.core.resource.attachment.service
 
 import com.wafflestudio.csereal.common.CserealException
-import com.wafflestudio.csereal.common.controller.AttachmentContentEntityType
+import com.wafflestudio.csereal.common.entity.AttachmentAttachable
 import com.wafflestudio.csereal.common.properties.EndpointProperties
 import com.wafflestudio.csereal.core.about.database.AboutEntity
 import com.wafflestudio.csereal.core.academics.database.AcademicsEntity
@@ -31,7 +31,7 @@ interface AttachmentService {
     ): AttachmentDto
 
     fun uploadAllAttachments(
-        contentEntityType: AttachmentContentEntityType,
+        contentEntityType: AttachmentAttachable,
         requestAttachments: List<MultipartFile>
     ): List<AttachmentDto>
 
@@ -80,7 +80,7 @@ class AttachmentServiceImpl(
 
     @Transactional
     override fun uploadAllAttachments(
-        contentEntityType: AttachmentContentEntityType,
+        contentEntityType: AttachmentAttachable,
         requestAttachments: List<MultipartFile>
     ): List<AttachmentDto> {
         Files.createDirectories(Paths.get(path))
@@ -186,7 +186,7 @@ class AttachmentServiceImpl(
         }
     }
 
-    private fun connectAttachmentToEntity(contentEntity: AttachmentContentEntityType, attachment: AttachmentEntity) {
+    private fun connectAttachmentToEntity(contentEntity: AttachmentAttachable, attachment: AttachmentEntity) {
         when (contentEntity) {
             is NewsEntity -> {
                 contentEntity.attachments.add(attachment)
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/resource/mainImage/service/MainImageService.kt b/src/main/kotlin/com/wafflestudio/csereal/core/resource/mainImage/service/MainImageService.kt
index 219c883e..d84cbded 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/resource/mainImage/service/MainImageService.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/resource/mainImage/service/MainImageService.kt
@@ -1,7 +1,7 @@
 package com.wafflestudio.csereal.core.resource.mainImage.service
 
 import com.wafflestudio.csereal.common.CserealException
-import com.wafflestudio.csereal.common.controller.MainImageContentEntityType
+import com.wafflestudio.csereal.common.entity.MainImageAttachable
 import com.wafflestudio.csereal.common.properties.EndpointProperties
 import com.wafflestudio.csereal.core.about.database.AboutEntity
 import com.wafflestudio.csereal.core.council.database.CouncilEntity
@@ -27,7 +27,7 @@ import java.nio.file.Paths
 
 interface MainImageService {
     fun uploadMainImage(
-        contentEntityType: MainImageContentEntityType,
+        contentEntityType: MainImageAttachable,
         requestImage: MultipartFile
     ): MainImageDto
 
@@ -47,7 +47,7 @@ class MainImageServiceImpl(
 
     @Transactional
     override fun uploadMainImage(
-        contentEntityType: MainImageContentEntityType,
+        contentEntityType: MainImageAttachable,
         requestImage: MultipartFile
     ): MainImageDto {
         Files.createDirectories(Paths.get(path))
@@ -99,7 +99,7 @@ class MainImageServiceImpl(
     }
 
     // TODO: 각 entity의 interface로 refactoring하기.
-    private fun connectMainImageToEntity(contentEntity: MainImageContentEntityType, mainImage: MainImageEntity) {
+    private fun connectMainImageToEntity(contentEntity: MainImageAttachable, mainImage: MainImageEntity) {
         when (contentEntity) {
             is NewsEntity -> {
                 contentEntity.mainImage = mainImage
diff --git a/src/main/kotlin/com/wafflestudio/csereal/core/seminar/database/SeminarEntity.kt b/src/main/kotlin/com/wafflestudio/csereal/core/seminar/database/SeminarEntity.kt
index 01f36a51..54a7bbb3 100644
--- a/src/main/kotlin/com/wafflestudio/csereal/core/seminar/database/SeminarEntity.kt
+++ b/src/main/kotlin/com/wafflestudio/csereal/core/seminar/database/SeminarEntity.kt
@@ -1,8 +1,8 @@
 package com.wafflestudio.csereal.core.seminar.database
 
 import com.wafflestudio.csereal.common.entity.BaseTimeEntity
-import com.wafflestudio.csereal.common.controller.AttachmentContentEntityType
-import com.wafflestudio.csereal.common.controller.MainImageContentEntityType
+import com.wafflestudio.csereal.common.entity.AttachmentAttachable
+import com.wafflestudio.csereal.common.entity.MainImageAttachable
 import com.wafflestudio.csereal.common.utils.cleanTextFromHtml
 import com.wafflestudio.csereal.core.resource.attachment.database.AttachmentEntity
 import com.wafflestudio.csereal.core.resource.mainImage.database.MainImageEntity
@@ -58,14 +58,12 @@ class SeminarEntity(
     var plainTextAdditionalNote: String?,
 
     @OneToOne
-    var mainImage: MainImageEntity? = null,
+    override var mainImage: MainImageEntity? = null,
 
     @OneToMany(mappedBy = "seminar", cascade = [CascadeType.ALL], orphanRemoval = true)
-    var attachments: MutableList<AttachmentEntity> = mutableListOf()
+    override var attachments: MutableList<AttachmentEntity> = mutableListOf()
 
-) : BaseTimeEntity(), MainImageContentEntityType, AttachmentContentEntityType {
-    override fun bringMainImage(): MainImageEntity? = mainImage
-    override fun bringAttachments() = attachments
+) : BaseTimeEntity(), MainImageAttachable, AttachmentAttachable {
 
     companion object {
         fun of(seminarDto: SeminarDto): SeminarEntity {