• 한국통신학회논문지
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• 제25권1B호
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• pp.1-7
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• 2000

일반적으로 일차원 광부호분할 다중접속 시스템은 광직교코드를 사용하여 부호화와 복호화를 수행하지만 이차원 광부호분할 다중접속 시스템에서는 병렬 데이터의 전송을 위하여 이차원의 광직교패턴코드를 사용하여 부호화와 복호화를 수행한다. 이 때 사용되는 광직교패턴코드는 자기상관값과 상호상관값 특성이 좋아야 하지만, 송수신단간의 시간에 대한 정보나 패턴의 동기화가 보장된다면 자기상관값에 대한 조건을 완화시킬 수 있으며 생성할 수 있는 패턴코드의 수도 늘어나게 된다. 본 논문에서는 2차원 데이터의 병렬전송을 위한 광부호분할 다중접속 시스템을 소개하고 2차원 패턴코드의 생성방법에 대하여 알아보며 제시된 생성방법에 대하여 다른 사용자의 간섭잡음에 의한 확률밀도함수와 그에 다른 각 패턴코드의 비트오율을 유도한다. 임계치 및 동시사용자수에 대한 비트오율을 통해 시스템의 성능을 확인하여 최적의 광직교패턴코드 생성의 조건을 제안한다.

• 한국광학회지
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• 제18권2호
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• pp.149-154
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• 2007

저가의 소자 개발이 가능한 나노임프린팅 공정을 도입하여 510 nm 주기의 브래그 격자 구조를 가지는 폴리머 광도파로 소자를 제작하였다. 폴리머 격자 광소자의 온도 의존성을 감소시키기 위한 방법으로 플라스틱 박막으로 이루어진 유연성 기판상에 브래그 격자를 제작하는 것이 필요하다. 임프린팅 공정을 손쉽게 수행하기 위한 광도파로 구조를 채택하였으며, 코아와 클래딩의 굴절률이 각각 1.540, 1.430인 폴리머를 이용하여 코아 두께가 $3{\mu}m$인 단일모드 광도파로 구조를 얻을 수 있었다. 유연성 기판 브래그 격자 광도파로 소자의 특성을 Si기판 브래그 격자 광도파로 소자와 비교하여 관측한 결과, 유연성 기판 도입에 따른 브래그 반사 소자의 성능 저하는 나타나지 않았다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1848-1859
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• 2011

A subsidiary-main track for passenger station is a low-speed track section distinct from a through route such as a main track. It is parallel to a through track and connected to it at both ends by switches. Sidetracks allow for fast, high priority trains to pass slower or lower priority trains going the same direction. They are important for efficiency to order and organize the flow of rail traffic. In this paper we first describe the minimum headway between trains using the concept of occupation time in a block section, which depends on block systems, signalling system and safety technology. And then a stepwise approach is presented to select station, which is suitable to install sidetrack for a given train-traffic pattern. This approach is tested with sample example data, which are surveyed from track geometry based on the to-be-constructed line.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.215-218
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• 2004

The pseudolites are ground-based transmitters that can be configured to emit GPS-like signals with the purpose of enhancing the GPS by providing increased accuracy, integrity, and availability. Although the use of the pseudolites offers many potentially significant benefits, a number of technical issues must also be addressed. One is the pseudolite signal power level which is related with near-far problem, and other issues include deployment requirements, signal data rate, signal integrity monitoring, and user antenna location and sensitivity. In order to solve the near-far problem, the frequency offset or the pulsing schemes is implemented in most the pseudolites. However, in the case of the previous pulsing scheme with the fixed code pattern, the near-far problem still remains. This paper aims to design a sequential pulsing scheme to avoid the near-far problem. A pulse mode pseudolite has less interference than the continuous mode.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2891-2894
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• 2003

This paper describes the possibility of analyzing gait pattern from the variation of the lower leg electrical impedance. This impedance is measured by the four-electrode method. Two current electrodes are applied to the thigh and foot., and two potential electrodes are applied to the lateral aspect. medial aspect, and posterior position of lower leg. We found the optimal electrode position for knee and ankle joint movements based on high correlation coefficient, least Interference, and maximum magnitude of impedance change. From such features of the lower leg impedance, it has been made clear that different movement patterns exhibit different impedance patterns and impedance level.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2911-2914
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• 2003

Conventionally, biological manipulations have been performed manually with long training and pretty low success rates. To overcome this problem, a novel biological manipulation system has been developed to manipulate biological cells without any interference of a human operator, In this paper, we demonstrate a development of tole-autonomous Cell Manipulation System (CMS) using an image processing at a remote site. The CMS consists of two manipulators, a plane stage, and an optical microscope. We developed deformable template-model-matching algorithm for micro objects and pattern matching algorithm of end effect for these manipulators in order to control manipulators and the stage. Through manipulation of biological cells using these algorithms, the performance of the CMS is verified experimentally.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2887-2890
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• 2003

This paper describes the possibility of analyzing gait pattern from the variation of the lower leg electrical impedance. This impedance is measured by the four-electrode method. Two current electrodes are applied to the thigh, knee, and foot, and two potential electrodes are applied to the lateral, medial, and posterior position of lower leg. The correlation coefficients of the joint angle and the impedance change from human leg movement was obtained using electrogoniometer and 4ch impedance measurement system developed in this study. We found the optimal electrode position for ankle, knee and hipjoint movements based on high correlation coefficient, least interference, and maximum magnitude of impedance change. The correlation coefficients of the ankle, knee, and the hip movements -0.87, 0.957 and 0.80. respectively. From such features of the lower leg impedance, it has been made clear that different movement patterns exhibit different impedance patterns and impedance level. This system showed possibility that lower leg movement could be easily measured by impedance measurement system with a few skin-electrodes.

• 한국광학회지
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• 제7권3호
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• pp.287-294
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• 1996

MOCVD(metal-organic chemical vapour deposition)방법으로 성장시킨 이중 이종접합구조 GaAs/AlGaAs 웨이퍼를 이용하여 광위상변조기를 제작하였다. 제작과정에서 도파로와 절연층의 형성시 동일 포토레지스트 패턴을 이용하는 자기종렬공정을 개발하여 그 효용성을 입증하였다. Fabry-Perot 간섭법을 이용하여 변조기의 위상변조효율을 측정하였으며 1.31.mu.m파장에서 TE 편광의 경우 22.5.deg./Vmm의 위상변조특성을 얻었다.

• 한국자동차공학회논문집
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• 제5권5호
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• pp.188-196
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• 1997

Many researchers have developed the measurement technique of in-cylinder flow characteristics and found the effect of intake port geometries on engine performance. The flow characteristics of four-valve cylinder head were examined in a steady flow rig for different intake ports. Tumble intensity of intake configurations with different entry angles were quantified with a tumble meter. The velocity and angular momentum distributions in the tumble adaptor were measured under steady conditions with PIV(Particle Image Velocimetry). We have obtained the results that flow structure becomes complicated by valve interference at low valve lift. As the valve interferences were reducing and the flow pattern changed to large vortex structure with tumble direction, intake ports with different entry angles have different tumble centers. Tumble eccentricity of intake port with low entry angle was large, so that the port had relatively much angular momentum compared to others which was expected to improve combustion performance.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.267-272
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• 1993

This paper presents the performance and problems in analysis method and testing system of Electronic Speckle Pattern Interferometry (ESPI) method, in measuring two-dimensional in-plane displacement. The anyalysis result of measurement by ESPI is quite comparable to that of measurement by strain gauge method. This implieds that the method of ESPI is a very effective tool in non-contact two-dimensional in-planc strain analysis. But there is a controversal point,measurment error. This error is discussed to be affected not by ESPI method itseif, but by its analysis scheme of the interference fringe,where the first-order interpolation has been applied to the points of strain measured. In this case, it is turned out that the more errors would be occured in the large interval of fringe. so, this paper describes a computer method for drawing when the height is available only for some arbitary collection of points, the method is based on a distance-weighted, least-squares approximation technique, with the weight varying with the distance of the data points.