• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.8
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• pp.56-63
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• 1995

A new method is presented for the synthesis of lossy tapered transmission line having presecribed frequency characteristic in the passband. The theory of lossy case extends lossless cases suggested by Klopfenstein and others, and a special optimization process based on the Fourier transfrom pair and generalized Taylor's procedure is proposed for exact designs of frequency-dependent and distance-dependent lossy tapered line. The process is achieved by control of zero points of lobe-like input reflection coefficient. The validity of the suggested method is confirmed by synthesizing a lossy microstrip transformer and analyzing the simulation results.

• Journal of the Korean Institute of Telematics and Electronics
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• v.2 no.1
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• pp.10-13
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• 1965

본논문은 단종된 전송선과 개방된 전송선 및 2개의 결합저항기로 구성된 초광대역전송선형 FM변별기의 동적인 해석(dynamic analysis)을 취급하였다. 변별기의 출력파형의 Harmonic Distortion과 입력신호의 최대허용주파수변위와의 제관계를 Fourier transfrom으로 상세하게 해석하였다. 결합저항계수r(Fig 1 참조)는 변별기의 감도와 입력신호의 전주파수변위에 걸쳐 입력 Impedance가 일정하다는 견지에서 일로 놓아야 된다는 것이 판명되었다. 이론상으로는 100%의 주파수변위를 가진 FM신호라도 본변별기로 불과 2.6% Harmonic distortion으로 검파할 수 있으며 또한 검파시에 변별기의 입력 Impedance는 전종선의 특성 Impedance Z0로 일정하게 유지된다. 이론적인 결과를 뒷받침하기 위하여 실험결과를 첨부하였다. 본실험에서는 변별기의 특성곡선이 중심주파수 85.5Mc를 중심으로 40%의 주파수변위에 대하여 Linear하며, 또한 이때의 변별기의 입력 Impedance의 변화율은 이상치 Z0의 ±14% 이내이다.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.673-676
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• 1998

Future land remote sensing satellite systems will kikely be constrained in terms of communication band-width. To alleviate this limitation, the data must be compressed. Image data obtained from satellite exhibit a high degree of spatial and spectral correlations that must be properly exploited. In this paper we propose multispectral image data compression using wavelet transform and selective predicted vector quantization. Th eproposed method is based on accuratly predicting other band from reference band and reducing bit rate through threshold map. we can achieve better compression effeciency than conventional methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.10
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• pp.1444-1453
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• 1993

비 구조적인 주면 환경에서 평면 팔레트(planar pallet)를 포크리프트(forklift)로 적재하거나 하역하기 위한 물류용 재료운송 로보트 시스템을 제안한다. 제안한 시스템은 음향(acoustic)센서와 시각(visual) 센싱데이타를 사용하여 팔레트에 지정된 2개의 스롯(slot)의 위치를 결정하고 포크리프트를 팔레트의 스롯에 인게즈(engage) 한다. 본 연구에서는 재료운송 시스템의 복잡성을 줄이기 위해서 폴라로이드(Poraloid) 음향센서의 3차원 거리 데이터와 CCD 카메라에서 얻은 2차원 시각 네이타를 통합하는 방법을 개발한다. 2개의 다른 소스로부터 얻은 데이타는 서로의 미비점을 보안하며 재료운송 로보트 시스템을제어하기 위한 효율적인 알고리즘을 제공한다. 카메라는 far-away vision 개념에 의한 음향센서의 선형 스캔닝(scanning) 대역을 우선 결정한다. 선형 스캔닝에 의하여 얻어지는 거리 데이타(range Map)는 least mean square방법을 사용하여 팔레트의 위치와 자세(position and orientation)를 결정한다(near vision). 팔레트에 대한 위치와 자세가 결정되면 다시 시각센서를 이용하여(close vision) 에지(edge)탐지와 Hough transfrom 기술을 적용하여 팔레트에 대한 포크리프트의 인게이지먼트 위치를 구한다. 개발된 시스템은 하드웨어와 소프트웨어로 구현하고 평가하며 실험적인 결과도 제시한다.

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.478-481
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• 1997

Hadamard Transform Spectrometer (HTS) is an instrument which measures the spectrum of a source with high signal to noise ratio using multiplexing advantage. While the conventional HTS has the 1-dimensional characteristics because it measures only the spectrum, the system presented in this paper is 2-dimensional so that it can measure the spectrum of each position. We introduce here 2-dimensional Hadamard transform spectrometer and analyze it. The $T^{-1}$ method which recover the spectrum and compensate the transmissive nonideality of the stationary electro-optical mask(EOM) are applied to the system. By computer simulations we show we can get better estimates from the proposed system than that from the conventional HTS.

• Journal of the Semiconductor & Display Technology
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• v.6 no.3
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• pp.55-59
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• 2007

Wavelet Transform is amenable to efficient algorithms. So wavelet transform was adopted many signal processing and communication applications. For example, the wavelet transform was adopted as the transform for JPEG2000. However, Wavelet has weakness about smoothness along the contours and limited directional information. Hence, recently, some new transforms have been introduced to take advantage of this property. So we use to other transform, called contourlet transform in compression. In this paper, we propose a new method for image compression based on the contourlet transform, which has been recently introduced. Contourlet transform has a good result about images with smooth contours. Moreover, Contourlet is feasible multiresolution and multidirection expansion using non-separable filter bank. This treatise shows a good image representation after compressing using contourlet transform.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.27-29
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• 2018

본 논문은 상 전류의 위치(전기각)를 기반으로 보상전압을 결정하는 새로운 데드타임 보상알고리즘을 제안한다. 제안하는 알고리즘은 보상전압을 결정하는데 있어, 전류의 극성대신 제어하는 상 전류의 위치(전기각)를 이용하기 때문에 추가적인 알고리즘 없이 간단하게 보상전압을 정의할 수 있다. 또한 제안하는 데드타임 보상알고리즘은 동기좌표계에 바로 적용가능하기 때문에 3상 전압형 인버터(VSIs; Voltage Source Inverters)에 일반적으로 사용되는 동기좌표기반 제어기에 적용이 용이하고 추가적인 변환과정 없이 동기좌표에서의 인버터 출력전압을 추정할 수 있다. 제안하는 데드타임 보상알고리즘의 효과와 성능을 검증하기 위하여 전압형 3상 인버터를 이용한 L-R부하 실험이 진행되었으며, 상 전류파형의 FFT(Fast Fourier Transfrom)와 THD(Total Harmonic Distortion)를 산정하여 정량적 분석을 병행하였다.

• Proceedings of the KSEEG Conference
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• 2000.04b
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• pp.308-310
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• 2000

Sampling rates become inconsistent when spatial data in spherical coordinate are re-sampled with respect latitudinal or longitudinal degree for mathematical processes such as Fourier Transfrom, and this results in the distrtions of the processed data in the wavenmber domain. This distortions are more evident in the polar regions. An example is presented to show such distortions during the recovery process of free-air gravity anomalies from ERSI radar atimeter data in Russian Arctic Barents Sea, and a method is present to minimize the distortion using Lambect Conformal Conic map projection.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.1991-2000
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• 1994

In this paper, an alagorithm with six types of classification is suggested for the recognition system of hand-written Korean characters. After thinning process and truncating process for noise redection. The input images are used generalized by $64\times64$ size. The six type classification is composed of preliminary and secondary classification process by using the learning algoritm of multi-layer perceptron. Subblock Hough transform is used as local feature and sampling Hough transform is used as global feature. Experiment is conducted for 1800 characters which is written 31 times per each type by 10 persons. The 90% recognition rate is resulted by the preliminary classification of detection the final consonant and by the secondary classification of detecting the vowels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7C
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• pp.671-680
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• 2009

The diagnostic medical images(CT, MRI) in PACS require large storage and long transmission time. A simple and cheap way of overcoming these limitations is to increase the compression ratio. However, this requires a clinical validation for accurate diagnostic applications. The aim of this paper is to improve the compression efficiency of lossless JPEG2000 for diagnostic CT images by performing a visual-Iossless threshold filtering in high frequency subband. A proposed method, based on 5/3 reversible DWT, provides different subband-threshold values according to the compression ratio and gives the high subjective quality to reconstructed diagnostic CT images.