Sanghyun (Scott) Chi

Electrical and Computer Engineering
The University of Texas at Austin

Austin, TX 78712
Tel: 512-506-8635, Cel: 512-587-2883

 

Resume Available in PDF

Research Interests	Education	Working Experience
Publications	Patents	Skills
Honors and Awards	Employability Status	Contact Information

Research Interests

• Speech Quality Assessment/Enhancement
• Speech Synthesis/Analysis
• Jittering Effect on VoIP Services
• Time-Warping, Noise Compression
• Scalable Bit-rate Speech Coders
• Communications System

 

 

Education

• Ph. D. Candidate in Electrical and Computer Engineering, 08/03 ~ 05/09
  University of Texas at Austin, GPA: 3.89/4.0
  
• Master of Science in Electrical Engineering, February 2002
  Hanyang University, Korea, GPA : 4.0/4.0
  
• Bachelor of Science in Electrical Engineering, February 2000
  Hanyang University, Korea, GPA : 4.0/4.5

  RELATED GRADUATE COURSE
  Probability and Stochastic Process I, Psychoacoustics, Digital Signal Processing, Data Mining, Real-Time DSP Lab, Digital Time Series Analysis, Digital Image, Digital Speech, Data Compression, Communication Theory, Digital Communications, Wireless Communications, Linear Algebra, Optimization in Engineering Systems, VLSI-1, Acoustics (Auditory)

  DISSERTATION TITLE
  NONINTRUSIVE SPEECH QUALITY ASSESSMENT BASED ON A SUPPORT REGRESSION MODEL:

  Based on data-driven models, nonintrusive speech quality assessment (SQA) apparatus is suggested. SQA parameters are extracted on the basis of analyzing human auditory system and speech production system. The proposed SQA is applicable for achieving optimal channel bandwidth based on perceived speech quality.

  THESIS TITLE
  A STUDY ON THE LSP QUANTIZER FOR WIDEBAND SPEECH CODEC AND THE FAST ENCODING ALGORITHM FOR NNVQ
  

 

Working Experience

• Chief of Teaching Assistant, Electronic and Computer Engineering Dept., University of Texas, Austin, 01/2006 ~ Present.
  - Organizing senior project design courses and supporting course instructors.
  - Supervising technical teaching assistants
  - Supervising and guiding projects in various fields such as Acoustics, Telecommunications, DSP, Robotics, etc.
  
• Cooperation R & D intern, Qualcomm Inc., San Diego, CA, 05/05 ~ 08/05
  Project title: “Optimization Vocoder for VoIP”
  - Assessment of the performances of modified systems to optimize using system resource.
  - Developed an algorithm of puncturing information under the condition of successive transmission of information
  Project title: “Time warping for wideband speech codec”
  - Developed time warping algorithm for high band region.
  - Worked on developing C solution of high band region and on combining low band and high band time warping signal.

• Researcher, Samsung Advanced Institute of Technology, Yongin, Korea, 09/02 ~ 07/03.
  Project title: “Speech synthesis and signal processing” sponsored by Ministry of Information and Telecommunication of Korea
  - Developed a wideband speech codec: Low-band based on the G729 Annex A, High-band encoded by using MLT coefficients
  - Developed fixed-point solution (integer version) for assembly programming.
  - Programmed assembly language (ARM-9) high-band region.
  Project title: “Design Voice User Interface” in cooperation with Samsung Electronics.
  - Developed a 4 kbps codec for the Samsung PDA by using Embedded Visual C++ 3.0.
  - Developed fixed-point solution for assembly programming.
  - Programmed assembly solution of ARM-9 and Teak-Lite DSP processor.
  Project title: “Establishing the Korea standard in wideband vocoder based on internet” sponsored by Samsung Electronics
  - Developed the structure of scalable speech encoder/decoder.
  - Tested the quality of developed codec.

• Part-time Researcher, SozoTek, Austin, TX, 01/05 ~ 03/05.
  Project title: “Developing the objective quality measurement of cellular phone camera images”
  - Developing a new measurement for classifying images to apply different algorithms.

• Research Assistant, Electronic, Electrical, Control and Instrumentation, Hanyang University, Seoul, Korea, 03/00 ~ 02/02.
  Project title: “Developing encoding algorithm for high quality speech codec” in cooperation with Electronics and Telecommunications Research Institute in Korea
  - Designed a fast encoding algorithm in vector quatization: Using statistical MSE property of the nearest code word corresponding to the each input vector.
  - Programmed the assembly solution of developed algorithm using Oak DSP assembler.
  Project title: “Developing a wideband speech codec using W-CDMA and DSP (Oak core) solution for real-time implementation” in cooperation with Samsung Electronics in Korea.
  - Designed a LSP quantizer for the wideband speech codec which required high speech quality: Using pyramid quantizer which has lattice structure and introducing the concept of Safety-net.
  - Programmed solution of designed LSP quantizer using Oak assembler.
  Project title: “Developing 1.2 kbps speech codec for low bit transmitting rate” in cooperation with Electronics and Telecommunications Research Institute in Korea
  - Designed low-bit rate speech codec.
  - Developed LSP quatizer which are linearly combined, encoded and then transmitted per two frames.
  - Optimized the structure of codec for low bit rate transmission.

• Teaching Assistant, School of Electronic and Computer Engineering, Hanyang University, Seoul, Korea, Fall/01, Spring/01.
  - Served as an assistant of System Design Laboratory.
  - Served as a teaching assistant of Electrical Circuit 2

 

Skills

• Experience in the speech signal processing business: CELP codec, Low bit-rate codec, VQ, speech enhancement, sub-band coding, waveform interpolation, time-warping, parametric voice coding, perceptual quality analysis

• Vast understanding of vocoders: AMR, G.729 series, G.723.1, EVRC, 4GV

• Extensive knowledge of human auditory/speech-production system

• Assembly languages: Oak DSP, Teak DSP, TI TMS320C54x, ARM-9(Strong ARM)

• High-level languages: Embedded visual C++, C, C+

• Algorithm development environment: MATLAB, Mathematica

• Electronic design automation tools: Cadence, Verilog, P-SPICE, ORCAD, VHDL, LABVIEW

• Bilingual: Korean/English

• Excellent leadership and team skills
  

Publications  

• Sanghyun Chi, and Baxter F. Womack, “Speech quality assessment for VoIP services using the support vector regression model,” submitted to IEE Letter.
  
• Youngok Kim, Haewoon Nam, Sanghyun Chi, and Baxter F. Womack, “An adaptive patterned-subcarrier allocation algorithm for low-complexity OFDM system,” IEEE Vehicular Tech. Conf..
  
• Sanghyun Chi, Sangwon Kang, Yongserk Kim and Kwangcheol Choi, “A study on a fast search algorithm for vector quantization”, The Acoustic Society of Korea Trans..
  
• Sanghyun Chi, Sangwon Kang and Chankil Lee, “Safety-net pyramid VQ of LSF parameters for wideband speech codecs”, IEE letters.
  

Patents

• Sanghyun Chi and Serafin Diaz,: “Vocoding method and apparatus for puncturing speech frames without significantly affecting speech quality”, US Provisional Application No. 60/760,639.
  
• Sanghyun Chi, Sangwon Kang, Seongkyu Hwang, Yongserk Kim and Namil Lee: “Fast search method for nearest neighbor vector quantization”, Korea GP2002060051.
  
• Sanghyun Chi, Sangwon Kang and Beongsik Yoon: “LSP quantizer using predictive pyramid vector quant-izer for wideband speech codec”, Korea GP2001015675 and US 6,988,067 B2.
  
• Sanghyun Chi, Changyong Son, Kangeun Lee, and Sangwon Kang: “Bitrate scalable speech coding and de- coding apparatus”, Korea GP20030046324; US Pregrant 20050010404
  
  

Honors and Awards

• Recipient of Technology Workforce Development Grant, University of Texas, Austin, 08/2008

• Recipient of Engineering Scholarship of ECE Dept., University of Texas, Austin, 07/2007

• Recipient of the scholarship of Korea Science and Engineering Foundation: 08/2003~07/2005

• Recipient of the 21st Century Science scholarship of Hanyang Univerisity: 03/2000~02/2002

• Recipient of the scholarship of the honors: Fall/1999

• Recipient of the scholarship of the honors: Spring/1999

• Recipient of the scholarship of the honors: Fall/1998

• Recipient of the scholarship of the honors: Fall/1993
  

 

Employablilty Status: US Citizen/Permanant Resident

 

Contact Information

E-mail: schi@ece.utexas.edu; cap2glong@gmail.com

Web: http://www.ece.utexas.edu/~schi/