Lionel Blog

Profile

HoChul Jeon
hybridego@gmail.com

Summary

Embedded systems expert with extensive Linux and Android-based Firmware, Platform, and Server development. Participated in Android porting and platform work from early versions (Cupcake). Deep analysis of Camera, Audio, SurfaceFlinger, Multimedia HAL/Framework, with hands-on projects. Experience in Device Driver porting, Customized Native Services, System mods, NDK apps. Proficient in C/C++, Python, Go, Kotlin for full-stack from embedded to server. Multiple smart speaker, robot, IoT projects.

Technical Stack

Languages

• Proficient: C/C++, Python, Go, Java, Kotlin
• Learning: Rust (currently building projects)

Development

• Buildroot, Yocto, Linux Device Driver(Modification Level), Android HAL/NDK/SDK
• ROS/ROS2, IAR, QT, SDL, Vue3, ESP32 Firmware, Electron (Node.js)

Multimedia

• FFmpeg, GStreamer, ALSA/TinyALSA, DMB, PulseAudio, Pipewire, pulseaudio

DB

• SQLite, PostgreSQL, MariaDB (MySQL), Neo4j,

DevOps / Containerization

• Docker, Docker Compose, Kubernetes (K8s)

Tools

• Vim, Android Studio, IntelliJ, VS Code, Cursor
• JIRA (Project Mgmt), Git (Version Control)

Certifications

• Vocational Training Instructor Level 3 (Sep 2009)
• Information Processing Technician (Oct 2007)

Publications

• All About Android NDK (2012, Hanbit Media)

Education

• Korea University of Technology and Education
  B.S., Internet Software Engineering (Multimedia)

Experience

Hanwha Vision (May 2024 – Present)

• Body Worn Camera: Field surveillance camera video control (HW Codec).
  Tech: C++, Buildroot, CMake, Python, HW Codec, Docker(containerized development environment).
• Public Audio System: Building broadcast system.
  Tech: C++, PulseAudio, ALSA, Go, Vue, RTP, Multicast, SQLite3, Docker(containerized development environment).

Hyundai Autoever (Sep 2023 – May 2024)

• CCIC / P-OIP (Android Automotive): OS-Navigation interface (ccIC27, P-OIP).
  Tech: Volley, Android Compose, Kotlin, AIDL, C++, D-Bus, Go, JNI, Android Automotive.

Kakao Enterprise (Dec 2019 – Aug 2023)

• Kakao Home: IoT platform server modernization and third-party integration maintenance.
  Tech: Spring Boot, Kotlin, Docker, Kubernetes (K8s), Vault, OAuth2, Logstash, Elasticsearch, Kibana, GitHub, MySQL, Redis. Deployment: Deployed with Docker images on Kubernetes — implemented rolling updates, Horizontal Pod Autoscaling (HPA) for server scaling, and Ingress-based redundancy/load‑balancing (NGINX Ingress).
• Robot Tech Testing: Indoor serving robot device/server dev.
  Tech: ROS/ROS2, SLAM, Cartographer, Navigation2, Go, MQTT, MySQL, KakaoTalk Chatbot.
• Smart Office Setup: Sensor/dashboard devices, servers, apps.
  Tech: Nordic nRF52840, Matter OpenThread, MQTT-SN, Python (BeautifulSoup, Selenium), Django, Electron, Node.js, Vue3.
• Kakao Mini Hexa: Linux smart speaker porting, Mic Tuning/BMT.
  Tech: Qualcomm QCS404, Yocto Linux, OTA, DSPC solution, Python automation.
• Kakao Mini C Audio Enhancement: Audio tuning, 32bit→64bit migration.
  Tech: GoodHz EQ solution, Android Audio HAL.

Kakao (Oct 2014 – Nov 2019)

• Kakao Mini Link: IoT device Bluetooth stack mods (BLE, A2DP, HFP).
• Kakao Mini C: Android smart speaker (MT8167, RK3326) dev.
• Kakao Mini 1st Gen: Full Android BSP (NXP4330, porting, HAL, OTA, Aging Test, BT/WiFi, Audio Precision automation).
  Tech: Linux Device Driver, Android Porting, HAL, Native Daemon, SELinux, Android App, BT/WiFi, Audio Precision, Ellisys Bluetooth Vanguard, Docker(Development environments and toolchain were containerized as Docker images for reproducible local builds and CI pipelines.)
• IDC Efficiency: ESP32 sensor device (power/temp/humidity/airflow collection).
  Tech: ESP32 esp-idf, MQTT, WiFi, Ethernet.
• TV Closed Caption Extractor: TV TS decoding, caption/audio extraction & streaming.
  Tech: FFmpeg, libiconv, TCP server.
• Video Encoder Accel Server: HW encoder testing (Nexel 4330, Nvidia Jetson, FPGA).
  Tech: FFmpeg, GStreamer, NVENC.
• Song Recognition Broadcast Receiver Upgrade: Linux-based receiver (Android → Linux).
  Tech: Buildroot, TV/Radio Driver, FFmpeg, RTSP, Syslog, MPEG-TS, Audio Resampling, Valgrind.

Daum Communications (Jan 2013 – Sep 2014)

• Bluetooth Beacon R&D: Event app (treasure hunt).
  Tech: Android SDK, Bluetooth LE.
• Indoor Air Quality Collector: Node/master firmware, Android app.
  Tech: BLE, Bluetooth Classic, WiFi, IAR, Android SDK.
• Song Recognition Broadcast Receiver - Phase 1: Android porting (Telechips TCC89xx).
  Tech: TV/Radio Driver, FFmpeg, DMB RTSP, Resampling.
• Daum TV: Set-top box tech internalization.
  Tech: Telechips Android BSP, TV/Radio Driver.

Insignal (Sep 2010 – Dec 2012; Jan–Aug 2010)

• TJ Media Japan Android Karaoke Remote: Debugging & perf testing.
• Android Native Framework Training: NDK materials (MDS, Samsung, LG, etc.).
• Android Navigation App: DMB driver porting, video player app.
  Tech: Linux Device Driver, Android NDK, FFmpeg.
• Android Multimedia Engine: Early Android video engine (multi-format support).

Other Projects

• Home Appliance Control Test: SSDP/UPnP via smart speaker (DDNS, Avahi).
• Unmanned Store: Camera placement, weight sensing devices.
• KT Children’s Monkey Robot (Mon-e): Embedded Linux robot control.
  Tech: SDL, Serial comm, NFC.
• Video Call Porting.