• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.6
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• pp.164-175
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• 1996

In this thesis, to cope with severe intersymbol interference and nonlinear distotions of the digital magnetic recording channel a neural decision feedback equalizer (NDFE) and an adaptive neural equalizer (NE) are applied. The digital magnetic recording channels with various recording densities and different types of the nonlinear distortions are considered. The computer simulation shows that as the nonlinear distortion is increased, the neural equalizers (NdFE, NE) have advantages of approximately 2-4 dB in signal to noise ratio (SNR) over the onventional eualizers to reach sme bit error rate and, a sthe recording density is increased, 1~5 dB of SNR improvement are also gained. Especially the NdFE gives a superior performance over the other equalizers when there is a severe nonlinear distortion in the digital magnetic channel.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.4
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• pp.26-35
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• 1997

This paper proposes a multi-bit $\Sigma\Delta$ modulator arcitecture which eliminates signal clipping problem. To avoid signal clipping, the output values of intgrators are monitored and modified by a reference value. This oepration is recorded as a digital code to restore actual signal value. Due to the digital code, the substraction of feedback value from the multi-bit quantizer can be calculated by a digital adder and this simplifies dAC operation making the accurate DAC of conventional multi-bit $\Sigma\Delta$ modulator scheme unnecessary. These features make N-th modulator can be implemented by sharing an integrator among N stages to decrease the required chip area. As an experimental example, a 4th order .sum..DELTA. modulator with oversampling ratio of 64 was simulated to show over 130 DB SNR at rail-to-rail input sinusoidal signal.

• 전기의세계
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• v.25 no.5
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• pp.59-62
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• 1976

Applications of the digital computers in the control systems are not new. But when one tries to integrate the control system with a digital computer to form a feedback loop, he has to solve a great deal of problems in both hardware and software aspects. Such problems are investigated in this paper. For the hardware aspect, one has to design interfaces for both ADC and DAC. Since these are absolutely necessary pieces of hardware, one can notavoid from using them. The interface which employ the programmed data transfer method was designed for this research. For the software aspect, one has to build models for the digital compensator and the controlled system. In order to do that it is necessary to utilize the real time clock and to write his own interrupt service routine. As a sample case, a deadbeat compensator was desinged and tested.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.05a
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• pp.199-202
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• 2002

This parer concerns a design methodology of the observer-based output-feedback digital controller for Takagj-Sugeno (TS) fuzzy systems using intelligent digital redesign (IDR). The term of IDR involves converting an analog fuzzy-mode-based controller into an equivalent digital one in the sense of state-matching. The considered IDR problem is viewed as convex minimization problems of the norm distances between linear operators to be matched. The stability condition is easily embedded and the separations principle is explicitly shown.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.231-232
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• 2008

본 논문은 협업 필터링(Collaborative Filtering)기반의 추천시스템에 필요한 알고리즘을 제안한다. 제안한 알고리즘은 사용자의 선호도를 Implicit Feedback을 통해 예측하는 Implicit Rating과 사용자 선호도와 컨텐츠의 정보를 바탕으로 사용자의 프로파일을 형성하는 Tag 기반의 사용자 프로파일과 P2P망 내에서 자신과 유사한 사용자 그룹을 형성하는 알고리즘으로 구성되어 있다. 제안한 알고리즘을 적용하여 Web Text 기반의 CF기반의 개인화 추천시스템을 구현하였으며 구현된 프로그램을 실제 사용자에게 배포하여 Feasibility를 검증하였다.

• Journal of IKEEE
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• v.17 no.3
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• pp.248-253
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• 2013

Frequency detector is a circuit that converts the frequency to a digital representation and finds its application in various fields such as modulator and synchronization circuitry. In this paper, a couple of first-order and second-order frequency discriminator structures are modeled and analyzed with their quantization noise sources. Also a delta-sigma frequency detector architecture is proposed. Through theoretical analysis and derived equations, the output noise is obtained, which is validated by simulation. The proposed all-digital frequency discriminator may be applied in the feedback path of the all-digital phase-locked loop.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.8
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• pp.798-803
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• 2007

In case of minimized digital camera and mobile digital camera, it's difficult to get the high quality image by conventional AE(Auto Exposure) algorithm because of restriction of system organization. In this paper, a new algorithm that adopts a target setting, a compensation of feedback delay and a gamma correction, etc, are suggested for improving a noise increase and an output sensitivity decrease due to system minimization. We also suggest a method using fuzzy logic which can decide more effectively the ES(Electric Shutter) value and the AGC(Analog Gain Control) value than conventional system.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.113-116
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• 2005

본 논문은 DOCSIS(Data Over Cable Service Interface Specifications)를 기반으로 하는 디지털 CATV(Cable TV)의 케이블 모뎀에서 적용이 가능한 이중모드 등화기의 모의실험 결과에 관한내용이다. 케이블 모뎀의 등화기는 훈련심벌이 없으므로 수신된 심벌을 가지고 채널을 보상하며 처음에는 블라인드 모드로 동작하다가 특정한 임계값보다 작을 경우 결정 지향 모드로 동작하는 이중모드구조를 가진다. 본 논문에서 AWGN과 rummler 채널을 사용하였으며, 64QAM과 256QAM에 대해 rummler 채널의 반사파 이득을 변화해 가면서 케이블 모뎀의 BER(Bit Error Rate)를 모의실험하였다. 또한 이중모드 등화기의 탭 수를 변화해 가면서 케이블 모뎀의 BER을 조사하였으며 fractionally spaced 이중모드 등화기와 symbol spaced 이중모드 등화기의 BER을 조사하였으며 FBF(Feedback Filter)의 유무에 따른 BER도 조사하였다.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2061-2063
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• 2002

상용 DVD 플레이어에서 불량디스크에 대한 재생성능을 향상시키는 기술은 제조업체에게는 다른 어떤 것보다 우선하는 중요한 성능상의 지표이다. 불량디스크를 유형별로 나누어 보면 스크래치 디스크, 지문 디스크, 틸트 불량디스크 등으로 구분할 수 있다. 본 논문에서는 이러한 불량디스크 중 틸트 불량 디스크에 대한 플레이어의 재생성능을 향상시키는 기법을 제안한다. 즉 디스크의 재생도중 검출되는 지터데이터를 궤환하여 별도로 구동되는 틸트모터를 제어함으로써 재생성능의 향상을 꽤한다. 또한 실험을 통하여 그 유효성을 검증한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.97-103
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• 2006

This paper described the design and performance evaluation of fiber optic gyro using digital closed-loop processing. For the feedback to null the gyro input rate, digital serrodyne modulation was employed, and for scale factor stabilization, the control circuits of modulation amplitude and optical power are implemented. Performance tests show that prototype fiber optic gyro has bias stability of 0.34 deg/hr, scale factor non-lineality of about 100ppm, and maximum measurement range of ${\pm}500$ deg/sec.