• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2001년도 학술대회논문집
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• pp.59-64
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• 2001

Transient in an electrical system are generated by lightning and switching. This paper presents analysis of switching and lightning surge, and means of limiting the voltage magnification transient for high voltage power systems by using EDSA's EMTAP software package. One means of limiting the voltage magnification transient is to convert the end-user power factor correction banks to harmonic filters. An inductance in series with the power factor correction bank was used to decrease the transient voltage at the customer bus to acceptable levees. The interception of the impulse from the phase wire is fairly straight forward by properly installed surge arresters. The simulation shows that the addition of the surge arrester at the customer location can achieve a substantial reduction of the transient magnitude.

• 전자공학회논문지C
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• 제34C권5호
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• pp.82-92
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• 1997

In this paper, we propose post-rpocessing method that corrects a misrecognized character by generated a characater recognizer using morphological analyzer and spelling corrector. The proposed post-processing consists of sthree phases : First, our method pass through morhological analyzer which only outputted necessary information for spelling correcting, doesn't analyze a bundle of phrases, and detects the location of misrecognized character. Second, tagging the generated candidate character using the information of character substitution table and grapheme substitution/separating table. Then we retry analysis after the misrecognition character has been substituted. Finally we select table, we investigate misrecognized charcters in CORPUS. Reliability analysis used to frequency of randomly selected about 100,000 words in CORPUS. A korean character recognizer demonstrates 93% correction rate without a post-processing. The entire recognition rate of our system with a post-processing exceeds 97% correction rate.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.270-273
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• 2007

In this paper, a SAR-despeck1ing approach of adaptive iteration based a Bayesian model using the lognormal distribution for image intensity and a Gibbs random field (GRF) for image texture is proposed for noise removal of the images that are corrupted by multiplicative speckle noise. When the image intensity is logarithmically transformed, the speckle noise is approximately Gaussian additive noise, and it tends to a normal probability much faster than the intensity distribution. The MRF is incorporated into digital image analysis by viewing pixel types as states of molecules in a lattice-like physical system. The iterative approach based on MRF is very effective for the inner areas of regions in the observed scene, but may result in yielding false reconstruction around the boundaries due to using wrong information of adjacent regions with different characteristics. The proposed method suggests an adaptive approach using variable parameters depending on the location of reconstructed area, that is, how near to the boundary. The proximity of boundary is estimated by the statistics based on edge value, standard deviation, entropy, and the 4th moment of intensity distribution.

• 천문학회보
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• 제38권1호
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• pp.69.1-69.1
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• 2013

We are developing Adaptive Optics (AO) system for 1m telescope at Gwacheon National Science Museum Observatory. The beam spot of the Gwacheon 1m telescope. The tip-tilt correction system consists of a CMOS sensor, a tip-tilt mirror and a feed back loop. The beam spot location at the CMOS sensor indicates the tip-tilt components of the incoming light. The tip-tilt mirror is controlled by DAC output voltage calculated by proportional-integral-derivative (PID) controller. This system successfully corrects the tip-tilt motion of the spot.

• 한국멀티미디어학회논문지
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• 제24권8호
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• pp.1059-1067
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• 2021

In this paper, a HDR algorithm for a single image is proposed using the exposure fusion, that adaptively calculates gamma correction coefficients according to the image distribution. Since typical HDR methods should use at least three images with different exposure values at the same scene, the main problem was that they could not be applied at the single shot image. Thus, HDR enhancements based on a single image using tone mapping and histogram modifications were recently presented, but these created some location-specific noises due to improper corrections. Therefore, the proposed algorithm calculates proper gamma coefficients according to the distribution of the input image and generates different exposure images which are corrected by the dark and the bright region stretching. A HDR image reproduction controlling exposure fusion weights among the gamma corrected and the original pixels is presented. As the result, the proposed algorithm can reduce certain noises at both the flat and the edge areas and obtain subjectively superior image quality to that of conventional methods.

• 한국수산과학회지
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• 제44권4호
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• pp.423-430
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• 2011

The most satisfactory split-beam transducer for fish sizing maintains a wide bearing angle region for correct fish tracking without interference from side lobes and lower sensitivity to fish echoes outside of the main lobe region to correctly measure the angular location of free-swimming fishes in the sound beam. To evaluate the performance of an experimentally developed 50 kHz split-beam transducer, the angular location of a target was derived from the electrical phase difference between the resultant signals for the pair of transducer quadrants in the horizontal and vertical planes consisting of 32 transducer elements. The electrical phase difference was calculated by cross-spectral density analysis for the signals from the pair of receiving transducer quadrants, and the directivity correction factor for a developed split-beam transducer was estimated as the fourth-order polynomial of the off-axis beam angle for the angular location of the target. The experimental results demonstrate that the distance between the acoustic centers for the pair of receiving transducer quadrants can be controlled to less than one wavelength by optimization with amplitude-weighting transformers, and a smaller center spacing provides a range of greater angular location for tracking of a fish target. In particular, a side lobe level of -25.2 dB and an intercenter spacing of $0.96\lambda$($\lambda$= wavelength) obtained in this study suggest that the angular location of fish targets distributing within a range of approximately ${\pm}28^{\circ}$ without interference from side lobes can be measured.

• 전기전자학회논문지
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• 제19권2호
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• pp.168-175
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• 2015

본 논문은 잔상효과를 이용해서 동영상 표출이 가능한 회전형 LED 전광판을 위한 FPGA 설계 기법을 제안한다. 제안된 기법은 역감마 보정과 오차 확산 방식을 이용한 데이터 보정 과정, 블록 인터리빙 과정, 데이터 시리얼 출력 과정 등의 3가지 과정으로 구성된다. 역감마 보정과 오차 확산 방식을 이용한 데이터 보정 과정은 영상 데이터를 선형 휘도 특성으로 변환하기 위한 역감마 보정과 역감마 보정에 의해 발생하는 저계조 휘도 감소 현상을 줄이기 위해 오차 확산 방식을 이용한 영상 데이터를 보정하는 단계이다. 영상 데이터 블록 인터리빙 과정은 가로열로 입력되는 프레임의 데이터를 입력순서에 맞추어 저장한 후, 세로열에 해당하는 데이터만을 읽어내는 단계이다. 데이터 시리얼 출력 과정은 고속으로 회전하는 LED Bar에 표출해야 할 데이터를 전송하기 위해서 회전 위치에 해당하는 병렬 데이터를 시리얼로 변환하여 LED Driver IC에 전송하는 단계이다. 제안된 FPGA 설계 기법의 정확성을 평가하기 위해서 FPGA는 Xilinx 사의 Spartan 6 계열의 XC6SLX45-FG484를 사용하였고 설계 툴은 ISE 14.5를 사용하였다. 역감마 및 오차확산 보정작업에 대한 정확한 동작, 블록 메모리 인터리빙 동작, 영상 데이터의 시리얼화 동작 등에 대하여 목표로 한 설정값과 시뮬레이션 결과값이 일치함을 확인 할 수 있었다.

• 한국지능시스템학회논문지
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• 제18권2호
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• pp.163-168
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• 2008

이동로봇의 위치인식과 이를 바탕으로 하는 주행시스템은 이동로봇 핵심기술 중의 하나이다. 무선 센서 네트워크는 저전력, 저가, 단순성 등이 주된 특징으로서 실내 위치인식 시스템의 응용에 있어서 많은 가능성을 지니고 있다. 본 논문에서는 ZigBee 기반 무선 센서 네트워크에 퍼지 모델링 방법을 사용하여 이동로봇의 실내 위치인식 알고리즘을 구현하여 이를 주행시스템에 적용하고자 한다. ZigBee 기반 센서 네트워크에서는 노드들 간의 거리를 인식하기 위해서 RSSI (Received Signal Strength Indication) 값을 이용하게 된다. 그러나 이 RSSI 값은 건물 주위 물체에 의해 왜곡되거나 반사되는 수신 신호의 특성에 의해 영향을 받게 된다. 따라서 정확한 거리 정보를 알아내기 위해서는 적절한 교정 방법이 필요하며, RSSI 값에 퍼지 모델링 기법을 이용하여 정확한 거리 정보를 추출하고자 한다. 또한 이 거리 정보를 바탕으로 동적 삼각측량법을 이용하여 이동로봇의 실내 위치를 효율적으로 인식하고 주변 상항 변화에 효과적으로 대처할 수 있는 주행 알고리즘을 개발하고자 한다.

• 대한교통학회지
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• 제17권3호
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• pp.7-20
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• 1999

차량의 정확한 위치를 자동적으로 파악하여, 차량위치정보를 필요로 하는 사용자에게 한눈에 파악할 수 있도록 지도정보와 합성하여 제공하는 차량위치파악 시스템에 관한 연구가 다양한 방법으로 발전되어져 왔다. 인터넷과 무선통신의 급속한 기술발전과 편리한 사용성, 경제성을 고려해 볼 때, 인터넷과 무선통신을 연결시킨 차량위치파악 시스템의 발전가능성 및 확장성이 클 것으로 생각된다. 이에 따라 실질적으로 기반 구축이 되어있는 현재 수준의 인터넷과 무선통신을 위성항법과 연결하여 차량위치파악 시스템을 실제로 구축해보고, 현재 제기되는 문제점들과 실시간 차량위치파악시스템을 위해 앞으로 더 개발/발전되어져야 할 기술들을 제시한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(2)
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• pp.281-284
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• 2000

This paper describes design of a (32, 28) Reed Solomon decoder for optical compact disk with double error detecting and correcting capability. A variety of error correction codes(ECCs) have been used in magnetic recordings, and optical recordings. Among the various types of ECCs, Reed Solomon(RS) codes has emerged as one the most important ones. The most complex circuit in the RS decoder is the part for finding the error location numbers by solving error location polynomial, and the circuit has great influence on overall decoder complexity. We use RAM based architecture with Euclid's algorithm, Chien search algorithm and Forney algorithm. We have developed VHDL model and peformed logic synthesis using the SYNOPSYS CAD tool. The total umber of gate is about 11,000 gates.