https://tailwind-nextjs-starter-blog.vercel.app/blog Junyoung Yang ko y@jun0.dev (Junyoung Yang) y@jun0.dev (Junyoung Yang) Mon, 27 Apr 2026 00:00:00 GMT https://tailwind-nextjs-starter-blog.vercel.app/blog/ollama-to-vllm-serving https://tailwind-nextjs-starter-blog.vercel.app/blog/ollama-to-vllm-serving Ollama 기반 LLM 서버에서 동시 요청 증가 시 발생하는 성능 병목을 분석하고, vLLM으로 서버를 전환해 동시 사용자 50명 수준까지 안정적으로 처리할 수 있도록 개선한 과정과 결과를 정리했습니다. Mon, 27 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글llmvllmkubernetesinfra https://tailwind-nextjs-starter-blog.vercel.app/blog/ollama-to-vllm-serving https://tailwind-nextjs-starter-blog.vercel.app/blog/ollama-to-vllm-serving I analyzed the performance bottlenecks that appeared when concurrent requests increased on an Ollama-based LLM server, then moved the serving layer to vLLM so it could stably handle around 50 concurrent users. Mon, 27 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글llmvllmkubernetesinfra https://tailwind-nextjs-starter-blog.vercel.app/blog/k3s-vllm-gpu-workload https://tailwind-nextjs-starter-blog.vercel.app/blog/k3s-vllm-gpu-workload Code Place의 AI 조교 기능을 운영 클러스터에서 실행하기 위해 드라이버, NVIDIA runtime, k3s containerd 설정, RuntimeClass, device plugin을 맞춰간 기록입니다. Sun, 26 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글kubernetesk3svllmcudainfra https://tailwind-nextjs-starter-blog.vercel.app/blog/k3s-vllm-gpu-workload https://tailwind-nextjs-starter-blog.vercel.app/blog/k3s-vllm-gpu-workload How I prepared a k3s cluster to run Code Place AI assistant workloads with NVIDIA drivers, container runtime configuration, RuntimeClass, and device plugin checks. Sun, 26 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글kubernetesk3svllmcudainfra https://tailwind-nextjs-starter-blog.vercel.app/blog/longhorn-cnpg-troubleshooting https://tailwind-nextjs-starter-blog.vercel.app/blog/longhorn-cnpg-troubleshooting Code Place 운영 중 PostgreSQL 인스턴스 문제처럼 보였던 장애를 Kubernetes, CloudNativePG, Longhorn, 노드 레이어로 나눠 확인하며 원인을 좁혀간 기록입니다. Sat, 25 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글kuberneteslonghorncnpgpostgresqlinfra https://tailwind-nextjs-starter-blog.vercel.app/blog/longhorn-cnpg-troubleshooting https://tailwind-nextjs-starter-blog.vercel.app/blog/longhorn-cnpg-troubleshooting How I narrowed down a PostgreSQL startup issue in Code Place by separating CloudNativePG, Kubernetes, Longhorn, and node-level storage signals. Sat, 25 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글kuberneteslonghorncnpgpostgresqlinfra https://tailwind-nextjs-starter-blog.vercel.app/blog/longhorn-mount-conflict-multipathd https://tailwind-nextjs-starter-blog.vercel.app/blog/longhorn-mount-conflict-multipathd Code Place 운영 중 Longhorn 볼륨 마운트 실패를 Kubernetes 이벤트, share-manager 상태, ext4 메시지, multipathd 간섭 가능성까지 내려가며 추적한 기록입니다. Fri, 24 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글longhornkuberneteslinuxstorageinfra https://tailwind-nextjs-starter-blog.vercel.app/blog/longhorn-mount-conflict-multipathd https://tailwind-nextjs-starter-blog.vercel.app/blog/longhorn-mount-conflict-multipathd How I traced a Longhorn volume mount failure through Kubernetes events, share-manager state, ext4 messages, and possible multipathd interference. Fri, 24 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글longhornkuberneteslinuxstorageinfra https://tailwind-nextjs-starter-blog.vercel.app/blog/cnpg-rw-ro-endpoints https://tailwind-nextjs-starter-blog.vercel.app/blog/cnpg-rw-ro-endpoints Code Place 운영 중 read-only transaction 오류를 통해 CloudNativePG의 read-write, read-only 서비스 엔드포인트를 다시 확인한 기록입니다. Tue, 21 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글cnpgpostgresqlkubernetesdatabase https://tailwind-nextjs-starter-blog.vercel.app/blog/cnpg-rw-ro-endpoints https://tailwind-nextjs-starter-blog.vercel.app/blog/cnpg-rw-ro-endpoints How a read-only transaction error led me to verify CloudNativePG read-write and read-only service endpoints in Code Place. Tue, 21 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글cnpgpostgresqlkubernetesdatabase https://tailwind-nextjs-starter-blog.vercel.app/blog/grit-redis-room-state-sync https://tailwind-nextjs-starter-blog.vercel.app/blog/grit-redis-room-state-sync GRIT 실시간 화상 스터디 서비스에서 타이머, 발표자, 마이크 권한 같은 방 상태를 멀티 인스턴스 환경에서 일관되게 관리하기 위해 Redis Hash와 ZSET을 사용한 기록입니다. Mon, 20 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글spring-bootredislivekitwebrtcrealtime https://tailwind-nextjs-starter-blog.vercel.app/blog/grit-redis-room-state-sync https://tailwind-nextjs-starter-blog.vercel.app/blog/grit-redis-room-state-sync How I used Redis Hash and ZSET to keep timers, presenters, and microphone permissions consistent across multiple instances in GRIT. Mon, 20 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글spring-bootredislivekitwebrtcrealtime https://tailwind-nextjs-starter-blog.vercel.app/blog/spring-security-filter-exception-handling https://tailwind-nextjs-starter-blog.vercel.app/blog/spring-security-filter-exception-handling GRIT에서 JWT 인증 필터 에러가 공통 응답이 아니라 톰캣 500 에러로 내려오던 문제를 계기로 Spring Security의 예외 처리 경계를 정리한 기록입니다. Sat, 18 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글spring-securityjwtspring-bootbackend https://tailwind-nextjs-starter-blog.vercel.app/blog/spring-security-filter-exception-handling https://tailwind-nextjs-starter-blog.vercel.app/blog/spring-security-filter-exception-handling How I handled JWT filter exceptions in GRIT after authentication errors bypassed the common controller exception response. Sat, 18 Apr 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글spring-securityjwtspring-bootbackend https://tailwind-nextjs-starter-blog.vercel.app/blog/entity-validation-refactoring https://tailwind-nextjs-starter-blog.vercel.app/blog/entity-validation-refactoring GRIT의 사용자 프로필 초기화·수정 로직에서 검증과 대입이 반복되던 문제를 엔티티 내부 책임으로 정리한 기록입니다. Sun, 01 Mar 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) javarefactoringvalidationdomain-modelbackend https://tailwind-nextjs-starter-blog.vercel.app/blog/entity-validation-refactoring https://tailwind-nextjs-starter-blog.vercel.app/blog/entity-validation-refactoring How I moved repeated null and blank checks in GRIT profile logic into entity-level state change methods. Sun, 01 Mar 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) javarefactoringvalidationdomain-modelbackend https://tailwind-nextjs-starter-blog.vercel.app/blog/grit-observability-prometheus-loki-grafana https://tailwind-nextjs-starter-blog.vercel.app/blog/grit-observability-prometheus-loki-grafana GRIT 운영을 준비하며 Spring Actuator, Prometheus, Loki, Grafana로 메트릭과 로그를 수집하고 확인할 수 있게 구성한 기록입니다. Sun, 22 Feb 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) spring-bootprometheuslokigrafanamonitoring https://tailwind-nextjs-starter-blog.vercel.app/blog/grit-observability-prometheus-loki-grafana https://tailwind-nextjs-starter-blog.vercel.app/blog/grit-observability-prometheus-loki-grafana How I prepared basic monitoring for GRIT with Spring Actuator, Prometheus, Loki, and Grafana. Sun, 22 Feb 2026 00:00:00 GMT y@jun0.dev (Junyoung Yang) spring-bootprometheuslokigrafanamonitoring https://tailwind-nextjs-starter-blog.vercel.app/blog/timetable-ai-recognition https://tailwind-nextjs-starter-blog.vercel.app/blog/timetable-ai-recognition UniSchedule에서 시간표 이미지를 안정적인 일정 데이터로 바꾸기 위해 GPT Vision과 구조화 출력을 사용하며 프롬프트를 개선한 기록입니다. Sat, 25 Oct 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) aiprompt-engineeringstructured-outputbackend https://tailwind-nextjs-starter-blog.vercel.app/blog/timetable-ai-recognition https://tailwind-nextjs-starter-blog.vercel.app/blog/timetable-ai-recognition How I used GPT Vision and structured output to convert timetable images into reliable schedule data in UniSchedule. Sat, 25 Oct 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) aiprompt-engineeringstructured-outputbackend https://tailwind-nextjs-starter-blog.vercel.app/blog/unischedule-redis-pubsub-schedule-events https://tailwind-nextjs-starter-blog.vercel.app/blog/unischedule-redis-pubsub-schedule-events 팀 일정 관리 서비스(UniSchedule) 개발 중 발생한 멀티 인스턴스 환경의 채팅 메시지 전파 문제를 Redis Pub/Sub의 도입으로 해결해보았습니다. Mon, 20 Oct 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글spring-bootredispubsubawsarchitecture https://tailwind-nextjs-starter-blog.vercel.app/blog/unischedule-redis-pubsub-schedule-events https://tailwind-nextjs-starter-blog.vercel.app/blog/unischedule-redis-pubsub-schedule-events How I fixed chat message propagation issues in UniSchedule by introducing Redis Pub/Sub for a multi-instance backend environment. Mon, 20 Oct 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) 대표글spring-bootredispubsubawsarchitecture https://tailwind-nextjs-starter-blog.vercel.app/blog/webclient-vs-resttemplate https://tailwind-nextjs-starter-blog.vercel.app/blog/webclient-vs-resttemplate UniSchedule에서 외부 API를 연동하며 RestTemplate과 WebClient 사이에서 공식 지원 방향, 설정 유연성, 현재 MVC 구조와의 균형을 기준으로 선택한 기록입니다. Mon, 15 Sep 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) springwebclienthttp-clientbackend https://tailwind-nextjs-starter-blog.vercel.app/blog/webclient-vs-resttemplate https://tailwind-nextjs-starter-blog.vercel.app/blog/webclient-vs-resttemplate How I chose WebClient for external API integration in UniSchedule by considering official direction, configuration flexibility, and the current MVC architecture. Mon, 15 Sep 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) springwebclienthttp-clientbackend https://tailwind-nextjs-starter-blog.vercel.app/blog/ondelete-vs-jpa-cascade https://tailwind-nextjs-starter-blog.vercel.app/blog/ondelete-vs-jpa-cascade 상품 삭제 시 옵션까지 함께 삭제해야 하는 요구사항에서 Hibernate @OnDelete와 JPA Cascade를 비교하며 영속성 컨텍스트 일관성을 기준으로 선택한 기록입니다. Wed, 25 Jun 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) jpahibernatecascadedatabasebackend https://tailwind-nextjs-starter-blog.vercel.app/blog/ondelete-vs-jpa-cascade https://tailwind-nextjs-starter-blog.vercel.app/blog/ondelete-vs-jpa-cascade How I compared Hibernate @OnDelete and JPA Cascade for deleting product options while keeping persistence context consistency in mind. Wed, 25 Jun 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) jpahibernatecascadedatabasebackend https://tailwind-nextjs-starter-blog.vercel.app/blog/circular-reference-lazy-limit https://tailwind-nextjs-starter-blog.vercel.app/blog/circular-reference-lazy-limit 선물하기 API 구현 중 ProductService와 OptionService가 서로 참조하며 발생한 순환 참조 문제를 @Lazy로 덮지 않고 의존 방향과 책임 분리 관점에서 다시 본 기록입니다. Fri, 20 Jun 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) springdependency-injectionarchitecturebackend https://tailwind-nextjs-starter-blog.vercel.app/blog/circular-reference-lazy-limit https://tailwind-nextjs-starter-blog.vercel.app/blog/circular-reference-lazy-limit How I used a circular dependency between ProductService and OptionService as a signal to revisit responsibility boundaries instead of just hiding it with @Lazy. Fri, 20 Jun 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) springdependency-injectionarchitecturebackend https://tailwind-nextjs-starter-blog.vercel.app/blog/pageable-input-validation https://tailwind-nextjs-starter-blog.vercel.app/blog/pageable-input-validation Spring Pageable을 그대로 노출했을 때 정렬 기준과 페이지 크기 계약이 느슨해지는 문제를 PageRequestDto로 통제한 기록입니다. Wed, 18 Jun 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) springpaginationvalidationapi-design https://tailwind-nextjs-starter-blog.vercel.app/blog/pageable-input-validation https://tailwind-nextjs-starter-blog.vercel.app/blog/pageable-input-validation How I controlled page size and sort fields by wrapping Spring Pageable input with a request DTO. Wed, 18 Jun 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) springpaginationvalidationapi-design https://tailwind-nextjs-starter-blog.vercel.app/blog/pagination-count-query-cost https://tailwind-nextjs-starter-blog.vercel.app/blog/pagination-count-query-cost 목록 조회 API를 만들며 Page가 자동으로 수행하는 count 쿼리 비용을 확인하고, Page와 Slice를 어떤 기준으로 선택할지 정리한 기록입니다. Sun, 15 Jun 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) jpapaginationspring-dataperformance https://tailwind-nextjs-starter-blog.vercel.app/blog/pagination-count-query-cost https://tailwind-nextjs-starter-blog.vercel.app/blog/pagination-count-query-cost How I compared Page and Slice after reviewing the cost of automatic count queries in list APIs. Sun, 15 Jun 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) jpapaginationspring-dataperformance https://tailwind-nextjs-starter-blog.vercel.app/blog/jpa-n-plus-one-problem https://tailwind-nextjs-starter-blog.vercel.app/blog/jpa-n-plus-one-problem 선물하기 API에서 연관 데이터를 조회하며 발생할 수 있는 JPA N+1 문제를 Fetch Join, EntityGraph, Batch Size 관점에서 비교한 기록입니다. Tue, 10 Jun 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) jpahibernatespringperformance https://tailwind-nextjs-starter-blog.vercel.app/blog/jpa-n-plus-one-problem https://tailwind-nextjs-starter-blog.vercel.app/blog/jpa-n-plus-one-problem A comparison of Fetch Join, EntityGraph, and Batch Size while handling related data queries in a gift API. Tue, 10 Jun 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) jpahibernatespringperformance https://tailwind-nextjs-starter-blog.vercel.app/blog/rest-delete-body-design https://tailwind-nextjs-starter-blog.vercel.app/blog/rest-delete-body-design 선물하기 API를 설계하면서 DELETE 요청에 데이터를 Body로 넘길지, Query Parameter나 Path Variable로 표현할지 검토한 기록입니다. Wed, 28 May 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) rest-apihttpapi-designbackend https://tailwind-nextjs-starter-blog.vercel.app/blog/rest-delete-body-design https://tailwind-nextjs-starter-blog.vercel.app/blog/rest-delete-body-design How I chose Path Variable over DELETE request body when designing a gift API delete endpoint. Wed, 28 May 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) rest-apihttpapi-designbackend https://tailwind-nextjs-starter-blog.vercel.app/blog/attacklab-buffer-overflow-writeup https://tailwind-nextjs-starter-blog.vercel.app/blog/attacklab-buffer-overflow-writeup Buffer Overflow 취약점을 이용해 5개 Phase를 해체하는 AttackLab 풀이 기록입니다. Code Injection과 ROP(Return-Oriented Programming) 두 가지 기법을 사용했습니다. Tue, 20 May 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) system-softwareassemblygdbx86buffer-overflowrop https://tailwind-nextjs-starter-blog.vercel.app/blog/uuid-index-performance https://tailwind-nextjs-starter-blog.vercel.app/blog/uuid-index-performance 프로젝트에서 식별자로 UUID를 사용할지 검토하며 UUIDv4, ULID, UUIDv7이 인덱스 성능과 정렬 특성에 어떤 차이를 갖는지 정리한 기록입니다. Tue, 20 May 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) uuiddatabaseindexperformance https://tailwind-nextjs-starter-blog.vercel.app/blog/attacklab-buffer-overflow-writeup https://tailwind-nextjs-starter-blog.vercel.app/blog/attacklab-buffer-overflow-writeup A writeup for solving the five AttackLab phases with buffer overflow, code injection, and ROP(Return-Oriented Programming). Tue, 20 May 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) system-softwareassemblygdbx86buffer-overflowrop https://tailwind-nextjs-starter-blog.vercel.app/blog/uuid-index-performance https://tailwind-nextjs-starter-blog.vercel.app/blog/uuid-index-performance A comparison of UUIDv4, ULID, and UUIDv7 from the perspective of index locality, ordering, and ID exposure. Tue, 20 May 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) uuiddatabaseindexperformance https://tailwind-nextjs-starter-blog.vercel.app/blog/bomblab-binary-bomb-writeup https://tailwind-nextjs-starter-blog.vercel.app/blog/bomblab-binary-bomb-writeup 주어진 Binary 파일을 GDB로 disassembly하고 디버깅하면서 6개 Phase와 Secret Phase를 해체한 BombLab 풀이 기록입니다. Mon, 19 May 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) system-softwareassemblygdbx86reverse-engineering https://tailwind-nextjs-starter-blog.vercel.app/blog/bomblab-binary-bomb-writeup https://tailwind-nextjs-starter-blog.vercel.app/blog/bomblab-binary-bomb-writeup A BombLab writeup for defusing six phases and the secret phase by disassembling and debugging the given binary with GDB. Mon, 19 May 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) system-softwareassemblygdbx86reverse-engineering https://tailwind-nextjs-starter-blog.vercel.app/blog/application-validation-select-update https://tailwind-nextjs-starter-blog.vercel.app/blog/application-validation-select-update 카카오테크캠퍼스 선물하기 API를 구현하며 DB 제약조건에만 맡길지, 애플리케이션에서 먼저 검증할지 고민한 기록입니다. Thu, 15 May 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) springjpavalidationdatabasebackend https://tailwind-nextjs-starter-blog.vercel.app/blog/application-validation-select-update https://tailwind-nextjs-starter-blog.vercel.app/blog/application-validation-select-update How I decided when to validate business rules in application code instead of relying only on database constraints. Thu, 15 May 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) springjpavalidationdatabasebackend https://tailwind-nextjs-starter-blog.vercel.app/blog/rag-pipeline-llm-hallucination https://tailwind-nextjs-starter-blog.vercel.app/blog/rag-pipeline-llm-hallucination DocDoc에서 의료 논문 기반 답변을 만들며, 질문만 LLM에 전달했을 때 생기는 근거 없는 답변 문제를 RAG와 SSE 스트리밍으로 줄인 기록입니다. Tue, 15 Apr 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) ragllmpineconelangchainai https://tailwind-nextjs-starter-blog.vercel.app/blog/rag-pipeline-llm-hallucination https://tailwind-nextjs-starter-blog.vercel.app/blog/rag-pipeline-llm-hallucination How I used RAG and SSE streaming in DocDoc to make medical-paper-based answers more grounded and usable. Tue, 15 Apr 2025 00:00:00 GMT y@jun0.dev (Junyoung Yang) ragllmpineconelangchainai https://tailwind-nextjs-starter-blog.vercel.app/blog/android-fragment-savedinstancestate https://tailwind-nextjs-starter-blog.vercel.app/blog/android-fragment-savedinstancestate Android 편의 앱을 만들며 백그라운드 복귀 후 Fragment 표시 상태가 깨지던 문제를 savedInstanceState와 생명주기 관점에서 해결한 초기 프로젝트 기록입니다. Sun, 15 Mar 2020 00:00:00 GMT y@jun0.dev (Junyoung Yang) androidfragmentlifecycledebuggingearly-project https://tailwind-nextjs-starter-blog.vercel.app/blog/android-fragment-savedinstancestate https://tailwind-nextjs-starter-blog.vercel.app/blog/android-fragment-savedinstancestate An early project record of fixing Fragment state restoration issues after returning from the background in an Android utility app. Sun, 15 Mar 2020 00:00:00 GMT y@jun0.dev (Junyoung Yang) androidfragmentlifecycledebuggingearly-project https://tailwind-nextjs-starter-blog.vercel.app/blog/iot-tcp-socket-lighting https://tailwind-nextjs-starter-blog.vercel.app/blog/iot-tcp-socket-lighting IoT 자율형 전등 프로젝트에서 NodeMCU와 Android 앱 사이의 상태를 실시간으로 주고받기 위해 HTTP polling 대신 TCP 소켓 서버를 만들었던 초기 프로젝트 기록입니다. Tue, 15 Oct 2019 00:00:00 GMT y@jun0.dev (Junyoung Yang) nodejstcpsocketiotearly-project https://tailwind-nextjs-starter-blog.vercel.app/blog/iot-tcp-socket-lighting https://tailwind-nextjs-starter-blog.vercel.app/blog/iot-tcp-socket-lighting An early project record of building a TCP socket server between NodeMCU and an Android app for real-time smart light control. Tue, 15 Oct 2019 00:00:00 GMT y@jun0.dev (Junyoung Yang) nodejstcpsocketiotearly-project