About me

• Name: Jiyong Youn (윤지용)
• Nickname: HLETRD
• Contacts
  • GitHub 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)

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Hobbies

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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.)

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Photography (2013-)

Astrophotography (2016-)

• Deep Sky, Landscape astrophotography
• Bronze medal winner of 27th astronomical photo contest from KASI
• AAPOD² winner of 2019-06-04 Eta Carina Nebula
• AAPOD² winner of 2019-02-10 Widefield view of Auriga
• AAPOD² winner of 2018-10-25 Around Eta Carina Nebula
• AAPOD² winner of 2018-08-29 IC 2177: Seagull Nebula
• AAPOD² winner of 2018-04-01 Widefield view of Gemini

Equipments

Photography

• Sony A7R V
• Panasonic Lumix DMC-LX10
• Sony Cyber-shot DSC-HX99

• Sigma 24-70mm f/2.8 DG DN Art
• Sony FE 100-400mm f/4.5–5.6 GM OSS
• Sony FE Carl Zeiss Sonnar T* 55mm f/1.8 ZA
• Tamron SP 70-300mm f/4-5.6 Di VC USD
• Samyang 14mm f/2.8 ED AS IF UMC
• Samyang AF 35mm f/2.8 FE
• Samyang 85mm f/1.4 AS IF UMC
• Samyang 135mm f/2.0 ED UMC
• Canon EF 50mm f/1.8 STM

• Sony A7 II
• Sony A5000
• Sony Alpha SLT-A65
• Sony 18-55mm f/3.5-5.6 DT SAM
• Sony FE 28-70mm f/3.5-5.6 OSS
• Minolta AF 70-210mm f/4
• Canon EF 200mm f/2.8 L USM II

Astrophotography

• QHY16200A
• QHY5L-II Mono
• Takahashi FSQ-106ED
• CRUX-170HD

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Skills & Works

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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

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Softwares

• Python
• C#
• PHP
• Java
  • Kotlin
  • Android
• Javascript
  • React
  • Express
• CUDA / OpenCL
• Go
• C++
• MATLAB

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Python 2/3 (2015-)

• The language I’ve fallen in love with.
• Also skilled in various frameworks. (Flask, Django, Numpy, Scipy, PyQt5, AstroPy …)
  • Contributor of AstroPy.ccdproc
• 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)

• Based on Python3, PyQt5, PySerial
• PC controller for CRUX-170HD / CRUX-320HD harmonic drive equatorial mount.

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)

• Based on the Lua/Torch implementation of neural style, and Python 2, Flask, MongoDB
• Covered up to 1000+ sessions
• Service discontinued

Others

• Outsources projects. Below are projects done in 2019.
  • TheChairs
  • SITUDY
  • etc…

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C# (2017-)

NanoFocus ASCOM drivers

NanoFocus PC console

Outsourced projects

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PHP5, PHP7, PHP8 (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

• Simple tool to design and simulate RFLP(
  Restriction Fragment Length Polymorphism) experiment, a very-common experiment in molecular biology.

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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

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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.

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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

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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.
  • Migrated from Sublime Text 3