• International Journal of Ocean System Engineering
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• 제1권1호
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• pp.1-8
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• 2011

Ocean structures and vehicles are exposed to severe ocean environment conditions such as waves, winds and currents. When such ocean structures and vehicles are designed, an accurate structure analysis is required to keep the system safely. Hydro-elastic analysis is one of key issues to design such structures and vehicles. In many previous investigations, numerical analyses for hydro-elastic problem have been used. In this study, an experimental analysis is carried out and the circular cylindrical shell is considered. Dynamical characteristics for a circular cylindrical shell are identified by experimental vibration analysis in air and water. The natural frequencies and mode shapes are compared in air and water to obtain hydro-elastic effects. Some interesting results are found in the variation of natural frequencies and damping ratios of the circular cylindrical shell for different water contact depths.

• 한국산학기술학회논문지
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• 제7권5호
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• pp.759-765
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• 2006

유기발광다이오드(OLED)증착을 위한 서큘러소스의 열전달 해석을 통하여 온도분포를 연구하였다. 대면적의 OLED용 평판의 유기물증착을 위해 서큘러소스가 사용되는데, 소스내의 유기물이 가열되고, 승화되어 증착된다. 유기물의 수율을 높이기 위해 히터설계를 개선하고, 이에 대한 열전달해석을 수행하였다. 그리고, 효율을 높이기 위한 새로운 제조공정인 OVPD공정의 개념과 유도 및 열전달특성에 관한 기본적인 연구결과를 제시하였다.

• 해양환경안전학회지
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• 제20권3호
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• pp.312-317
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• 2014

In this paper, the wave run-up height and depression depth around air-water interface-piercing circular cylinder have been numerically studied. The Reynolds Averaged Navier-Stokes equations (RANS) and continuity equations are solved with Reynolds Stress model (RSM) and volume of fluid (VOF) method as turbulence model and free surface modeling, respectively. A commercial Computational Fluid Dynamics (CFD) software "Star-CCM+" has been used for the current simulations. Various Froude numbers ranged from 0.2 to 1.6 are used to investigate the change of air-water interface structures around the cylinder and experimental data and theoretical values by Bernoulli are compared. The present results showed a good agreement with other studies. Kelvin waves behind the cylinder were generated and its wave lengths are longer as Froude numbers increase and they have good agreement with theoretical values. And its angles are smaller with the increase of Froude numbers.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.68-72
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• 1990

This paper describes a method of calculating the viewing parameters of a camera using a perspective view of a circular pattern. The proposed method determines the angle of pan, tilt, and swing, as well as the distance from the camera to the reference point of a world coordinate system, using simple equations. The proposed method is so simple and accurate that when used in a well-controled environment as in robot vision systems or visual inspection systems it may even seem trivial.

• 식물병연구
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• 제13권2호
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• pp.126-129
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• 2007

[ $2005{\sim}2006$ ]년 경기도 안성시와 화성시의 심비디움 재배 농가로부터 잎 뒷면에 검은색 구름덩이 모양의 병반을 형성하고, 잎의 앞면에는 원형 내지 타원형의 황색병반을 나타내는 병징이 관찰되었다. 병징이 진전되어 병반이 합쳐지면서 잎 전체가 황색의 원형 병반을 이루고, 잎 뒷면에서도 검은색 구름덩이가 합쳐져 그을음모양(sooty spot)을 나타낸다. 병징이 오래되면 잎 조직은 기능이 저하되어 결국은 암갈색 내지 검은색으로 변하며 잎이 마르게 된다. 본 연구에서는 심비디움에 발생한 검은잎마름병의 병징을 관찰하고, 병반에서 분리한 병원균의 균학적 특징을 조사한 결과 Pseudocercospora cymbidiicola로 동정되었으며 병원성 검정 결과 자연상태와 동일한 병징을 확인할 수 있었으므로 이 병을 Pseudocercospora cymbidiicola에 의한 심비디움검은잎마름병으로 명명할 것을 제안한다.

• 한국통신학회:학술대회논문집
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• 한국통신학회 1984년도 춘계학술발표회논문집
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• pp.37-41
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• 1984

The error rate performance of amplitude phase keying system has been studied in the environment of cochannel interference and impulsive noise. We have derived the error probability equations of amplitude shift keying signal and phase shift keying signal, and combining the results, we have evaluated the circular APK signal which is the one of the several cases of APK arrays. Using the derived equations, the circular APK system has been evaluated in terms of carrier-to-noise power ratio(CNR), carrier-to-interferer power ratio(CIR), and impulsive index. The graphic results show us the best case and worst case of APK system, and good performance compared to the other systems in cochannel interference and impulsive noise.

• Journal of Korean Society for Atmospheric Environment
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• 제9권E호
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• pp.347-357
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• 1993

The Lagrangian grid-free numerical method, the discrete vortex method, was applied to solve the Navier-Stokes euqations. This method avoids the introduction of numerical viscosity swamping the real physical viscosity at high Reynolds number, unlike Eulerian method, e.g. finite difference and element methods. The boundary integral equation method for the potential flow solution was included to make the discrete vortex method more feasible for complex geometries. The fast adaptive multipole expansion method was incorporated to reduce the computational time from $O(N^2)$ to O(N) for the computations of vortex-vortex interactions. The test problems were air flow around one circular cylinder and two circular cylinders in tandem with various gaps. The numerical results were in excellent gareement with the experimental and other computational results. The applicabilty of the method was discussed with the indoor and the outdoor air pollution problems, especially the contaminant transport in the recirculation regions.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.143-148
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• 2006

The goal of this paper is to analyze, through simulations and experiments, GNSS interference mitigation performance under various types of antenna structures against wideband and narrowband interferences using spatial-temporal adaptive signal processing (STAP) techniques. The STAP approach, which combines spatial and temporal processing, is a viable means of GNSS array signal processing that enhancing the desired signal quality and providing protection against interference. In this paper, we consider four types of 3D antenna array structure - Uniform Linear Array (ULA), Uniform Rectangular Array (URA), Uniform Circular Array (UCA), and the Single-Ring Cylindrical Array (SRCA) under an interference environment. Analytical evaluation and simulations are performed to investigate the system performance. This is followed by simulation GPS orbits in interfered environment are used to evaluate the STAP performance. Furthermore, experiments using a 2x2 URA hardware simulator data show that with the removal of wideband and narrowband interference through the STAP techniques, the signal tracking performance can be enhanced.

• 전자공학회논문지C
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• 제34C권10호
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• pp.51-58
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• 1997

In this paper, a technique ot estimate center positions of the circular parts under noisy condition is presented. The circle chords are segmented from the circle with successively varying angle and weighted to reduce the center estimation errors effected by the orientations of the circle chords. The weighting factors for variable length chords are adaptively detemined according to the error contribution of each chord in center estimation. Robust estimation of the center positions of the circular parts are possible even though the edge informations are partially contaminated by the non-uniform lighting or the background textures. Computer simulations for several images which are obtained for same object under real environment y camera, show that the proposed techniqeu yields 1.85 and 2.77 of estimated error-distribution for center position and radius in mean square error, that the proposed has more robust estimation than those of the conventional methods.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.415-420
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• 2009

Selective Catalytic Reduction(SCR) has been used for the reduction of $NO_x$ in a steam supply boiler. Recently, the reduction of $NO_x$ becomes an important research field because of its negative effect on an environment. Shape optimization of circular poles installed in the chamber, which is located in upstream of a SCR, has been performed using response surface method and three-dimensional Navier-Stokes analysis to enhance gas flow uniformity. Three design parameters, diameter, arranging angle and stretching ratio of circular poles, are considered in the present study. Throughout the shape optimization of a circular pole, gas flow uniformity is successfully increased by decreasing local recirculation flow in a square duct chamber. Recirculation flow observed in the corner of the square duct can be reduced by proper installation of a guide vane or a blunt body. Detailed flow characteristics are also analyzed and discussed.