About me

  • Name: Jiyong Youn (윤지용)
  • Nickname: HLETRD
  • Contacts
    • GitHub Facebook Email
    • I do not usually check comments on this site. Please contact me by Email.
  • Language
    • Korean (Native)
    • English
  • B. S. in Electrical and Computer Engineering at Seoul National University (2020)
  • Graduated Gyeonggi Science High School (2016)

Hobbies

Motorcycle (2018-)

  • 2019 KTM 390 DUKE (2021.02. -)
  • 2017 Honda CB650F (2019.05. – 2021.02.)
  • 2016 Yamaha MT-03 (2019.02. – 2019.05.)
  • 2018 Honda Super Cub (2018.09. – 2019.02.)

Photography (2013-)

Astrophotography (2016-)

Skills & Works

Hardwares

  • From designing to manufacturing of electrical circuits, including PCB designing, and programming of embedded microcontrollers/FPGA.
    • Experiences in STM32, FPGAs, ESP32, ESP8266 microcontrollers, AVRs, Arduinos, …
  • PCB EDA: Prefer Altium Designer, EasyEDA as an EDA tool.
  • 3D CAD/CAM: Prefer SolidWorks and Autodesk Fusion 360 for 3D product design and Autodesk AutoCAD for 2D design.
  • Raspberry Pi
    • Low performance and (relatively) low durability(compared to Cortex-M/R based controllers), but…it’s just cheap!
  • Outsourced projects…
  • Developed NanoFocus, an electronic focuser controller for astrophotography.
  • Developed focusing system & filter control system for SNU CEOU 24inch telescope

Programming

Python 2/3 (2015-)

  • The language I’ve fallen in love with.
  • Also skilled in various frameworks. (Flask, Django, Numpy, Scipy, PyQt5, AstroPy …)
  • Miscellaneous works are on my GitHub
Spectools (https://github.com/hletrd/spectools) (2017)
  • Spectral analysis tools for astronomy, based on Python and AstroPy.
JubeatInfo Festo (https://jubeatinfo.com) (2018-)
  • Website providing personalized stats & records of Jubeat Festo.
  • Based on Python 2, Flask, MongoDB
  • 500+ users
JubeatInfo Clan (http://c.jubeatinfo.com) (2017-2018)
  • Website providing personalized stats & records of Jubeat Clan.
  • Based on Python 2, Flask, MongoDB
  • 300+ users
QubellInfo (http://q.jubeatinfo.com) (2016-2017)
  • Website providing personalized stats & records of Jubeat Qubell.
  • Based on Python 2, Flask, MongoDB
  • 1000+ users
Acrux (https://github.com/hletrd/Acrux) (2017)
PyPreprocessor (https://github.com/hletrd/PyPreprocessor) (2017)
  • Based on Python 3, Astropy, Numpy,
  • Various scripts for processing observational data for astrophotography as well as astrophotometry.
Neural Style Online (https://github.com/hletrd/neural_style) (2015-2016)
Others
  • Outsources projects. Below are projects done in 2019.
    • TheChairs
    • SITUDY
    • etc…

C# (2017-)

NanoFocus ASCOM drivers
NanoFocus PC console
Outsourced projects

PHP5, PHP7 (2014-)

SAO Weather Monitor (2018-)
  • Automated weather monitor for SNU Astronomical Observatory
XpressEngine contributor (2016)
DDR Info (https://github.com/hletrd/DDR-Info) (2015)
  • Website provides personalized stats & records of Dance Dance Revolution.
  • 200+ users
  • Based on PHP, MySQL
YOTTA (https://github.com/hletrd/YOTTA) (2015)
  • Fully encrypted file storage.
  • Based on PHP, MySQL
River temperature API Link to API documentation (2015)
  • API providing water temperature of rivers in Korea.
RFLP Designer Demo

Java/Kotlin/Android (2014-)

  • Swing / AWT
TabletDroid (Link to Play store) (2014)
  • Make your Android phone to be used as a tablet(input device.)
  • PC client is based on Visual Basic 6
Outsourced projects

Javascript (2013-)

Hungry creator https://atik.kr/hungry/ (2018)
  • …
Awkward billiard (Experimental) (https://0101010101.com/labs/billiard/) (2015)
  • Based on HTML5 + Javascript
  • Awkward…
Simple word test (https://0101010101.com/labs/wordtest) (2013-2015)
  • Simple tool to memorize words fastly
TT4Them https://hletrd.github.io/TypingTutor4Them/ (2016)
  • IME-independant typing tutor application, running in browser.
  • Source code
HangangSwim (Link to Pebble App Store) (2016)
  • Based on Pebble.JS SDK
  • Simple app displaying water temperature of nearest river, with KOSPI/KOSDAQ informations.

GPU computing (2015-)

  • Moderately skilled in CUDA, OpenCL
Git hash miner (https://github.com/hletrd/gitminer-cuda) (2021)
  • To practice CUDA…
  • Found a lowest SHA1 hash (probably): 00000000000000c06d2e8c36f247206a9a4b1c63
GPUPhotometry (https://github.com/hletrd/GPUPhotometry) (2015)
  • Based on C + OpenCL + GTK+ + CFITSIO
  • Very fast CCD data reduction with GPU computing
MD5 maxmin solver (https://github.com/hletrd/md5-maxmin) (2015)
  • Based on C + OpenCL/CUDA
  • Now holding records for known MD5 extreme values.
  • Max: md5(0DbB^a2hxjdc_JiyongYoun-HLETRD) = fffffffffffffec29931c5489a14a02e
  • Min: md5(08ni(g0u3ada_JiyongYoun-HLETRD) = 00000000000000d4a49581c7f0638557
  • Popcount max: md5()to0wzR*x[L{WJ^y5G>B-HLETRD) = fb9fdfff13efffffffdfffe2efeffaff
  • Popcount min: md5(hhQ1/'jy5W^G[zwJ*RBL-HLETRD) = 0000098a020401801208448010004024
  • Bytesum max: md5(wWrC--3mn-a000000000-HLETRD) = fffae5f0faf8f9f5e6f0fafbf7f8e7f6
  • Bytesum min: md5(Gs4u^x4mn{4000000000-HLETRD) = 0405041602140309020a3c071702070a
  • …and a few other languages not listed above…
    • C(2010-), C++(2011-), especially for OpenCL, CUDA, and embedded systems(ARM Cortex-M, AVR)
    • Assembly newbie (x86, AVR, ARM Thumb/Thumb-2)
    • Visual Basic(2009-)… for XP-compatible applications…
    • HTML5, CSS, JS (For web dev)
    • BrainFuck

Others

  • Had prefered CentOS/RHEL than Ubuntu
    • But Ubuntu is more convenient now…
  • Prefer Git as VCS.
  • Prefer MariaDB along various RDBMSs.
  • Prefer MongoDB and Firebase along many NoSQLs.
  • Love Adobe CC products, especially Photoshop, Lightroom, Premiere, and Audition.
  • Use PixInsight as post-processing tool for astrophotography.
  • Participant, and gold medal winner of IBO 2014
    • Feel free to contact me if you are past IBO participant.
  • Use Visual Studio Code as the main text editor.