다중센서 영상융합을 위한 대응점 추출에 기반한 자동 영상정합 기법

최원철,정직한,박동조,최병인,최성남,Choi, Won-Chul,Jung, Jik-Han,Park, Dong-Jo,Choi, Byung-In,Choi, Sung-Nam 한국군사과학기술학회 2009 한국군사과학기술학회지 Vol.12 No.4

In this paper, we propose an automatic image registration method for multi-sensor image fusion such as visible and infrared images. The registration is achieved by finding corresponding feature points in both input images. In general, the global statistical correlation is not guaranteed between multi-sensor images, which bring out difficulties on the image registration for multi-sensor images. To cope with this problem, mutual information is adopted to measure correspondence of features and to select faithful points. An update algorithm for projective transform is also proposed. Experimental results show that the proposed method provides robust and accurate registration results.

난류유동 해석을 위한 ν_t-κ-γ 모델의 개발

최원철,서영민,최상규,정명균,Choi, Won-Chul,Seo, Young-Min,Choi, Sang-Kyu,Chung, Myung-Kyoon 대한기계학회 2009 大韓機械學會論文集B Vol.33 No.12

A new eddy viscosity equation was formulated from assumption of turbulence length scale equation and specific dissipation ratio equation. Then, a set of turbulence model equations for the turbulent kinetic energy ${\kappa}$, the viscosity ${\nu}_t$, and the intermittency factor ${\gamma}$ is proposed by considering the entrainment effect. Closure coefficients are determined by experimental data and resorting to numerical optimization. Present model has been applied to compute four representative cases of free shear flows and successfully compared with experimental data. In particular, the spreading rate, the centreline mean velocity and the profiles of intermittency are calculated with improved accuracy. Also, the proposed ${\nu}_t-{\kappa}-{\gamma}$ model was applied to channel flow by considering the wall effect and the results show good agreements with the Direct Numerical Simulation data.

확률분포 특성을 이용한 OFDM용 IFFT∪FFT프로세서 설계

최원철,이현,조경록,Choi, Won-Chul,Lee, Hyun,Cho, Kyoung-Rok 대한전자공학회 2003 電子工學會論文誌-SD (Semiconductor and devices) Vol.40 No.12

본 논문에서는 통계적 분석 방법으로 IEEE 802.11a WLAN의 OFDM 모뎀용 IFFT 및 FFT의 양자화 에러를 최소화하는 설계방법을 제안한다. 제안된 방법은 IFFT 및 FFT의 회전계수(twiddle coefficient)에 통계적으로 계산된 계수를 적용하여 회전계수를 수정하는 새로운 알고리즘을 사용한다. 본 논문에서는 알고리즘을 radix-2² SDF(single-path delay feedback) 구조에 적용하여 설계하였고 IFFT와 FFT의 대칭적 성질을 이용하여 회로블록을 공유하도록 하였다. 회로 레벨에서 설계된 입출력 10비트인 송신단의 IFFT와 수신단의 FFT가 자기루프 구조 가졌을 때 최대 양자화 오차는 0.0021이다. 기존의 선형확장 회전계수의 최대 양자화 오차가 0.0087로 측정되었기 때문에 제안된 프로세서가 3비트 효율이 좋다. In this paper, we propose an IFFT/FFT design method to minimize quantization error in IEEE 802.11a WLAN. In the proposed algorithm, the twiddle coefficient of IFFT/FFT processor is manipulated by the statistics distribution of the input data at each stage. We applies this algorithm to radix-2/$^2$ SDF architecture. Both IFFT and FFT processor shares the circuit blocks cause to the symmetric architecture. The maximum quantization error with the 10 bits length of the input and output data is 0.0021 in IFFT and FFT that has a self-loop structure with the proposed method. As a result, the proposed architecture saves 3bits for the data to keep the same resolution compared with the conventional method.

재구성 가능한 가변 포인트 IFFT/FFT 프로세서 설계에 관한 연구

최원철,전형구,이현,오현서,Choi Won-Chul,Goo Jeon-Hyoung,Lee Hyun,Oh Hyun-Seo 대한전자공학회 2004 電子工學會論文誌-TC (Telecommunications) Vol.41 No.12

무선 이동 통신은 고속의 이동성과 고속의 데이터 전송 능력을 요구하고 있다. 이러한 요구사항을 만족하기 위하여 물리계층에서 사용하는 모뎀 방식은 OFDM(Orthogonal Frequency Division Multiplex) 방식을 주로 사용한다. 앞으로 상용화되는 고속 무선 통신 방식에서 모뎀은 주로 IEEE 802.(11a, l6e, 등) 계열이 사용될 것이며, 물리레벨의 접속 방식에 구애받지 않는 가변적일 것을 요구하고 있다. 따라서 한 개의 모델에서 여러 가지 IEEE 802.(11a, 16e, 등) 계열 변조 및 복조 기능을 만족시키려면 다양한 크기의 IFFT(Inverse Fast Fourier Transform)/FFT(Fast Fourier Transform)를 수용할 수 있는 가변 포인트 IFFT/FFT 구조여야 한다. 본 논문에서는 재구성 가능한 IFFT/FFT 프로세서 설계 방법을 기술한다. 이 방법을 이용하면 재구성 가능한 모뎀을 실현할 수 있고 하나의 모뎀에서 서로 다른 OFDM 모뎀을 손쉽게 통합 할 수 있다. Wireless mobile communication systems request high speed mobility and high speed data transmission capability. In order to meet the requirements, OFDM(Orthogonal Frequency Division Multiplex) is mainly adopted in the physical layer of the wireless systems. In commercial wireless mobile systems, IEEE802.(11a, 16e, etc) series seem to be used as the modulation method. For supporting multiple air-interfaces in a wireless mobile system, different kinds of OFDM based modulation methods should be supported in one modem chip. It requires a variable point IFFT/FFT or reconfigurable IFFT/FFT processor. In this paper, we propose the design method of a reconfigurable IFFT/FFT processor. In addition, it is shown that a reconfigurable IFFT/FFT processor can he implemented by using the proposed method.

다중밴드 이득 보정기능을 갖는 디지털 청력보정회로 설계

최원철,이제훈,김영주,조경록,Choi Won-Chul,Lee Je-Hoon,Kim Young-Ju,Cho Kyoung-Rok 대한전자공학회 2004 電子工學會論文誌-SC (System and control) Vol.41 No.1

본 논문에서는 감음신경성 난청자의 비선형적으로 변하는 가청 한계값을 보상하는 청력보정회로를 제안한다. 제안된 청력 보정 회로는 주파수 대역에서 직접 보상하기 위해 FFT와 IFFT 프로세서를 사용하고, 회로크기를 줄이기 위해 입력신호 크기 제어 방식을 사용한다. 제안된 청력보정 회로는 기존의 FIR필터 구조가 적용된 청력보정 회로보다 다중밴드 이득 보정이 가능하기 때문에 주파수 보정능력이 감음신경성 난청자에 대해 약 $15\%$이상 향상된 결과를 나타낸다. 입력신호 제어방식 적용으로 입출력 비트가 제한되지 않은 프로세서보다 하드웨어 크기는 $65\%$ 감소된다. In this paper, we propose a new digital hearing aid circuit that compensates the impaired threshold level changing nonlinearly using a multi-band compensation technique. In the algorithm the hearing frequency range 8kHz is divided into 64 bands which is 125Hz resolution. Each band is controlled finely to compensate the hearing impaired proportional to personal ROM table. The multi-band is introduced using a FFT/IFFT Processor which makes to control in frequency domain. As a result, the proposed circuit is more efficient $15\%$ than a conventional ones such as FIR filter architecture in terms of the compensation gun and accuracy. The hardware size was reduced $65\%$ than a general FFT by pre-handling of the input data.

음향인식기술을 활용한 자동차 인식 조명제어 가로등 개발

최원철(Choi, Won-Chul),우중재(Woo, Choong-Chae) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.3

본 논문에서는 기존 가로등의 소비 전력을 줄이고 자동차의 유무에 따라 지능적으로 조명을 제어하는 효율적인 새로 운 조명제어 시스템을 제안한다. 제안된 새로운 조명제어 시스템은 자동차가 이동할 때 발생하는 음향을 수집하고 분석하여 자동차의 유무를 판별한다. 그리고 자동차 감지 정보를 통해 가로등의 조명을 제어하고 다음 가로등에 자동차 감지 정보를 전송하여 순차적으로 가로등을 점등한다. 실험결과, 자동차의 유무에 따라 조명을 제어하고 자동차의 이동방향을 판별하여 순차적으로 가로등이 점등하는 동작을 확인하였다. 이와 같은 시스템은 자동차의 이동이 적은 지방도로나 국도에서 비효율 적으로 항시 점등되어 있는 가로등에 적용하여 에너지를 절감할 수 있는 기술로 판단된다. In this paper, proposed a new lighting control system which can reduce power consumption compared to conventional street lamps and intelligently control the light efficiently depending on whether there is a vehicle on the street. The new lighting control system proposed by this paper detects the presence of cars by collecting and analyzing sounds generated by the movement of cars. Then, the system controls lighting of street lamps based on the above car detection information, and turns on the street lamps sequentially by transmitting the car detection information. Experimental results showed that lightings were controlled based on the presence of cars and that operations of the lamps were made by turning on the lights sequentially by determining the moving direction of cars. This system is considered a technology that can reduce energies by applying to local roads with a few cars moving or national highways where lights are always turned on with low energy efficiency.

자동차 개발과정에서 적용될 수 있는 Virtual Engineering 기술

최원철(Woncheol Choi) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_2

Virtual engineering is simulations of engineering activity performed in virtual environment to assist engineering decisions and controls. Virtual engineering can help bringing the detailed design to the early stage of product development. Thus, virtual engineering can be a critical tool for shortening product development schedule. Currently some advanced automobile companies such as chrysler have been actively employ virtual engineering in their product development, and reported a drastic improvement in product development time. In order to complete in the world market, Korean automaobile companies also need to employ virtual engineering. There are several obstacles for Korean automobile to overcome in the Processes of reaching to virtual engineering .The most important one is that they need to employ a master CAD model that can be used for geometric design, CAE analysis, and simulations.<br/>

노이즈 제거 알고리즘을 적용한 전도성 섬유 기반 손목형 ECG 시스템의 구현

최원철(Won-Cheol Choi),최정태(Jung-Tae Choi),이인수(In-Soo Lee) 한국정보기술학회 2018 한국정보기술학회논문지 Vol.16 No.8

In recent years, the convergence of IT technology and all industries is taking place rapidly. In the textile industry, smart clothes or smart fiber combined with IT technology are emerging as a future high value-added industry. In this paper, we implemented the conductive fiber-based wrist ECG (Electrocardiogram) system with noise rejection algorithm. Namely, electrodes using conductive fibers were manufactured in a band of wrist parts to measure ECG signals and to eliminate noise with a digital filter. The noise rejection algorithm was also used to minimize the malfunction rate during the activity. The experiment results show that the performances of the proposed wrist ECG system are good. In particular, we were able to avoid heart rate measurement errors that could be generated by user’s movements after wearing a fiber-type ECG system because of noise rejection algorithm.

볼텍스 튜브의 에너지 분리 현상에 관한 수치해석 연구

최원철(Won Chul Choi),정명균(Myung Kyoon Chung) 대한기계학회 2008 大韓機械學會論文集B Vol.32 No.2

The “energy separation phenomenon” through a vortex tube has been a long-standing mechanical engineering problem whose operational principle is not yet known. In order to find the operational principle of the vortex tube, CFD analysis of the flow field in the vortex tube has been carried out. It was found that the energy separation mechanism in the vortex tube consists of basically two major thermodynamic-fluid mechanical processes. One is the isentropic expansion process at the inlet nozzle, during which the gas temperature is nearly isentropically cooled. Second process is the viscous dissipation heating due to the high level of turbulence in both flow passages toward cold gas exit as well as the hot gas exit of the vortex tube. Since the amount of such a viscous heating is different between the two passages, the gas temperature at the cold exit is much lower than that at the hot exit.

LNG 스트리핑 펌프 개발

최원철(Won Chul Choi),유일수(Il Su Yoo),최종덕(Jong Duk Choi) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11