• The Journal of the Acoustical Society of Korea
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• v.15 no.2E
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• pp.24-32
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• 1996

A rigorous theory for modeling, analysis, optimum nonseparable filter bank in multidimensional M-band quantized subband codec are developed in this paper. Each pdf-optimized quantizer is modeled by a nonlinear gain-plus-additive uncorrelated noise and embedded into the subband structure. We then decompose the analysis/synthesis filter banks into their polyphase components and shift the down-and up-samplers to the right and left of the analysis/synthesis polyphase matrices respectively. Focusing on the slow clock rate signal between the samplers, we derive the exact expression for the output mean square quantization error by using spatial-invariant analysis. We show that this error can be represented by two uncorrelated components : a distortion component due to the quantizer gain, and a random noise component due to fictitious uncorrelated noise at the uantizer. This mean square error is then minimized subject to perfect reconstruction (PR) constraints and the total bit allocation for the entire filter bank. The algorithm gives filter coefficients and subband bit allocations. Numerical design example for the optimum nonseparable orthonormal filter bank is given with a quincunx subsampling lattice.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.100-109
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• 2000

In this paper a stepping motor drive electronic ratio control system for a metal belt CVT is suggested. The electronic ratio control system developed in this study is designed to control flow rate which is required to obtain the shift speed and to control the primary actuator pressure to maintain the desired ratio. Considering these control characterstics a fuzzy logic is used for the CVT ratio control. Using the fuzzy logic dynamic models of the ratio control system is investigated and compared with the experimental results. The experimental and simulation results show that the electronic ratio control system developed in this study can be used in CVT system for the active control of the speed ratio.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.378-381
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• 1991

In this paper, the active noise controll system in duct is analyzed with real time implementation. The primary noise signal detected by microphone is modeled using adaptive algorithm and the secondary signal which has the same amplitude and $180^{\circ}$ phase shift with the primary noise signal is generated in the controller. The signal processor DSP56001 is used to implement the real-time controller and the experimental results shows that our system can reduce the noise level in duct to $20{\sim}40$ [db].

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.623-626
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• 1991

Crucial to the success of the vector control scheme without speed sensor is up to computing instantaneous position of the rotor flux. In tracing this flux depending on the machine parameter, variations of those factor lead to the non-linear charlcteristic between I/O value and decrease overall efficiency of the vector control scheme. This paper, using recursive least square method estimating instantaneous value of the machine speed and parameter from the shift of current and voltage, proposes an algorithm for compensating the I/O error of the scheme.

• Journal of Sensor Science and Technology
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• v.17 no.4
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• pp.317-324
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• 2008

This paper presents an optical doppler tomography(ODT) system using a speaker as a method to achieve depth measurement in a flowing sample. The use of the speaker provides easy implementation with a low cost. The nonlinear characteristics of the speaker has hindered its adaptation because it produces inconsistent fringe frequencies at different depths. This paper reports an adaptive algorithm to compensate the nonlinear characteristics, and could, resultantly, acquire the Doppler frequency shift caused by the sample. The experiment utilizes a flowing scattering particle solution in a capillary tube at a certain flow rate. The Doppler frequency profile over the lumen was calculated by using spectrogram method. and we obtained the velocity image of the sample.

• International Journal of Automotive Technology
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• v.5 no.3
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• pp.201-208
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• 2004

Response characteristics of the CVT system for a parallel hybrid electric vehicle (HEV) are investigated. From the experiment, CVT ratio control algorithm for the optimal engine operation is obtained. To investigate the effect of the CVT system dynamic characteristics on the HEV performance, a hardware in the loop simulation (HILS) is performed. In the HILS, hardwares of the CVT belt-pulley and hydraulic control valves are used. It is found that the engine performance by the open loop CVT ratio control shows some deviation from the OOL in spite of the RCVs open loop control ability. To improve the engine performance, a closed loop control of the CVT ratio is proposed with variable control gains depending on the shift direction and the CVT speed ratio range by considering the nonlinear characteristics of the RCV and CVT belt-pulley dynamics. The HILS results show that the engine performance is improved by the closed loop control showing the operation trajectory close to the OOL.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.12
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• pp.61-67
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• 2005

This paper presents the carrier phase DGPS method providing a stable navigation solution under the condition of frequent blockage of the GPS signals. The proposed algorithm reject the channels having large errors using a clock bias drift and then calculated the more accurate solution. By investigating the relation between visible satellites` elevation and their clock bias drift, a proper threshold is set. Simulation shows that the presented result is as good as that of commercial system with real data.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.310-313
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• 2003

최근 들어 립리딩은 멀티모달 인터페이스 기술의 응용분야에서 많은 관심을 모으고 있다. 동적영상을 이용한 립리딩 시스템에서 해결해야 할 주된 문제점은 상황 변화에 독립적으로 얼굴 영역과 입술 영역을 추출하고 오프라인이 아닌 실시간으로 입력된 입술 영상의 인식을 처리하여 립리딩의 사용도를 높이는 것이다. 본 논문에서는 사용자가 쉽게 사용할 수 있는 PC카메라를 사용하여 영상을 입력받아 학습과 인식을 실시간으로 처리하는 립리딩 시스템을 구현하였다. 본 논문에서는 움직임이 있는 화자의 얼굴영역과 입술영역을 컬러, 조명등의 변화에 독립적으로 추출하기 위해 HSI모델을 이용하였다. 입력 영상에서 일정한 크기의 영역에 대한 색도 히스토그램 모델을 만들어 색도 영상에 적용함으로써 얼굴영역의 확률 분포를 구하였고, Mean-Shift Algorithm을 이용하여 얼굴영역의 검출과 추적을 하였다. 특징 점 추출에는 이미지 기반 방법인 PCA 기법을 이용하였고, HMM 기반 패턴 인식을 사용하여 실시간으로 실험영상데이터에 대한 학습과 인식을 수행할 수 있었다.

• Journal of Communications and Networks
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• v.8 no.2
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• pp.205-211
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• 2006

This paper considers the maximum likelihood (ML) detection of 16-ary differential amplitude and phase shift keying (DAPSK) in Rayleigh fading channels. Based on the conditional likelihood function, two new receiver structures, namely ML symbol-by-symbol receiver and ML sequence receiver, are proposed. For the symbol-by-symbol detection, the conventional DAPSK detector is shown to be sub-optimum due to the complete separation in the phase and amplitude detection, but it results in very close performance to the ML detector provided that its circular amplitude decision thresholds are optimized. For the sequence detection, a simple Viterbi algorithm with only two states are adopted to provide an SNR gain around 1 dB on the amplitude bit detection compared with the conventional detector.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1495-1498
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• 1987

This paper described the design of register part, ROM and entire digital filter implementation by merging with ALU, control part last year. The register part consists of shift register, parallel load serial output register, multiplexer and selector, and we designed specially the 1024 memory cells ROM and decoder to decode the register data. Also, presented scaling algorithm to prevent the overflow.