• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2011년도 전기공동학술대회 논문집
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• pp.213-213
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• 2011

Hydrophobic hairs of some insects make bubbles underwater. These bubbles makes possible for insects to breathe underwater. In this thesis, influence of geometric characteristics on air-liquid interface with pressure is investigated. Air-liquid interface shape with hair diameter over distance between hairs is analyzed This results expects to be used in the developments of artificial gill technology.

• 반도체디스플레이기술학회지
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• 제5권4호
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• pp.11-15
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• 2006

Expose equipment system that is used for manufacturing process of Flat Panel Display, is most important equipment in whole process. Expose equipment that is for making pattern of mask on substrate, consists of optical part, stage part and transport part. The stage is an important part that aligns mask and substrate for delivering pattern of mask to substrate exactly. In this paper, control system of expose stage that is able to use mask and substrate of diverse size, with PC controller using GUI interface instead of PLC control system. The existing PLC control system does not have the suitable structure for using mask of diverse size. GUI interface integration control system is based on PC. So it has the advantage of convenient use and active operation. We embodied PLC control system in integration control system based on PC, and verified utility possibility through the standard test course.

• 태양에너지
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• 제7권1호
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• pp.35-41
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• 1987

This paper presents a comprehensive computer simulation of hydrogenated amorphous p-i-n silicon solar cells. The physical mechanism governing solar cell operation has been modeled and solved numerically by Runge-Kutta-Gill method. Effects of gap state density, dopant impurity, diffusion length and interface recombination velocity on solar cell performance are investigated. Numerical results show that the electric field in i-region is not uniform but depends strongly on voltage and position. A rather poor fill factor may be due to the electric field variation and short diffusion length. It is found out that the life time should be improved in order to increase a fill factor and a conversion efficiency.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.73-78
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• 2003

In this research, we implement Realtime Air Diffusion Prediction System which is a parallel Fortran model running on distributed-memory parallel computers. The system is designed for air diffusion simulations with four-dimensional data assimilation. For regional air quality forecasting a series of dynamic downscaling technique is adopted using the NCAR/Penn. State MM5 model which is an atmospheric model. The realtime initial data have been provided daily from the KMA (Korean Meteorological Administration) global spectral model output. It takes huge resources of computation to get 24 hour air quality forecast with this four step dynamic downscaling (27km, 9km, 3km, and lkm). Parallel implementation of the realtime system is imperative to achieve increased throughput since the realtime system have to be performed which correct timing behavior and the sequential code requires a large amount of CPU time for typical simulations. The parallel system uses MPI (Message Passing Interface), a standard library to support high-level routines for message passing. We validate the parallel model by comparing it with the sequential model. For realtime running, we implement a cluster computer which is a distributed-memory parallel computer that links high-performance PCs with high-speed interconnection networks. We use 32 2-CPU nodes and a Myrinet network for the cluster. Since cluster computers more cost effective than conventional distributed parallel computers, we can build a dedicated realtime computer. The system also includes web based Gill (Graphic User Interface) for convenient system management and performance monitoring so that end-users can restart the system easily when the system faults. Performance of the parallel model is analyzed by comparing its execution time with the sequential model, and by calculating communication overhead and load imbalance, which are common problems in parallel processing. Performance analysis is carried out on our cluster which has 32 2-CPU nodes.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.607-614
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• 1996

A computer vision based automatic intelligent sorting system for dried oak mushrooms has been developed. The developed system was composed of automatic devices for mushroom feeding and handling, two sets of computer vision system for grading , and computer with digital I/O board for PLC interface, and pneumatic actuators for the system control. Considering the efficiency of grading process and the real time on-line system implementation, grading was done sequentially at two consecutive independent stages using the captured image of either side. At the first stage, four grades of high quality categories were determined from the cap surface images and at the second stage 8 grades of medium and low quality categories were determined from the gill side images. The previously developed neuro-net based mushroom grading algorithm which allowed real time on-line processing was implemented and tested. Developed system revealed successful performance of sorting capability of approximate y 5, 000 mushrooms/hr per each line i.e. average 0.75 sec/mushroom with the grading accuracy of more than 88%.

• Structural Engineering and Mechanics
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• 제50권1호
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• pp.53-71
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• 2014

A semi-analytical method is developed to consider free vibrations of a functionally graded elastic plate resting on Winkler elastic foundation and in contact with a quiescent fluid. Material properties are assumed to be graded distribution along the thickness direction according to a power-law in terms of the volume fractions of the constituents. The fluid is considered to be incompressible and inviscid. In the analysis, the effect of an in-plane force in the plate due to the weight of the fluid is taken into account. By satisfying the compatibility conditions along the interface of fluid and plate, the fluid-structure interaction is taken into account and natural frequencies and mode shapes of the coupled system are acquired by employing energy methods. The results obtained from the present approach are verified by those from a finite element analysis. Besides, the effects of volume fractions of functionally graded materials, Winkler foundation stiffness and in-plane forces on the dynamic of plate are elucidated.

• 한국산업정보학회논문지
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• 제13권3호
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• pp.31-37
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• 2008

MPEG 4 Part 20 LASeR (ISO/IEC 14496 20) is a specification designed to deliver rich media services in a mobile environment. The specification is an emerging standard that can replace the MPEG 4 BIFS specification designed to deliver PC based heavyweight media contents. The specification describes the representation of scene information in a resource constrained mobile environment. Unlike the BIFS standard designed to deliver heavyweight rich media, the LASeR specification has a restricted description that conforms to the SVG Tiny 1.2 specification. Also, the specification has an advantage of allowing for the efficient conversion of one graphics format to another. In this paper, we present the design and the implementation of a LASeR authoring system that allows for fast and efficient creation of interactive rich media contents in a mobile environment. The Gill interface of the authoring system presented in this paper allows users, who do not have prior knowledge of the scene description language, to conveniently create contents and store the produced scenes using the internal list data structure. The system allows users to navigate scene objects internally stored and to create LASeR XML files in the structured XML format.

• 한국정보처리학회논문지
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• 제5권12호
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• pp.3063-3076
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• 1998

멀티미디어 프리젠테이션에서 미디어의 함축된 의미를 효과적으로 전달하기 위해서는 미디어 데이터간에 존재하는 시간 및 공간적인 정보를 효과적으로 표현하고 처리할 수 있는 기법이 필요하다. 특히 이들 시간 및 공간 정보는 상호간 긴밀히 연결되어 있기 때문에 종합적인 표현 방법이 요구된다. 따라서 본 논문에서는 시공간의 동기화 정보를 종합적으로 표현하는 프리젠테이션 동기화 트리(PST)를 제안하고 있으며, 이 프리젠테이션 동기화 트리를 이용하여 효과적으로 프리젠테이션을 하는 수행 모델을 제안하고 있다. 특히, 본 모델에서는 사용자가 프리젠테이션을 위한 시나리오를 작성하기 위하여 특정한 사용자 인터페이스나 스크립트 언어를 익힐 필요 없이 Allen의 시간 모델에 기초하여 시간 관계를 간단하게 작성하기만 하면 되며, 실제 프리젠테이션을 위한 나머지 작업들로써 시간 관계의 일관성 검증 단계, PST 수행 단계 등을 거쳐 k동적으로 프리젠테이션 되도록 하였다.

• Journal of Ship and Ocean Technology
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• 제12권1호
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• pp.16-27
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• 2008

The interaction between advancing ships and the waves generated by them plays important roles in wave resistances and ship motions. Wave breaking phenomena near the ship bow at different speeds are investigated both numerically and experimentally. Numerical simulations of free surface profiles near the fore bodies of ships are performed and visualized to grasp the general trend or the mechanism of wave breaking phenomena from moderate waves rather than concentrating on local chaotic irregularities as ship speeds increase. Navier-Stokes equations are differentiated based on the finite difference method. The Marker and Cell (MAC) Method and Marker-Density Method are employed, and they are compared for the description of free surface conditions associated with the governing equations. Extra effort has been directed toward the realization of extremely complex free surface conditions at wave breaking. For this purpose, the air-water interface is treated with marker density, which is used for two layer flows of fluids with different properties. Adaptation schemes and refinement of the numerical grid system are also used at local complex flows to improve the accuracy of the solutions. In addition to numerical simulations, various model tests are performed in a ship model towing tank. The results are compared with numerical calculations for verification and for realizing better, more efficient research performance. It is expected that the present research results regarding wave breaking and the geometry of the fore body of ship will facilitate better hull form design productivity at the preliminary ship design stage, especially in the case of small and fast ship design. Also, the obtained knowledge on the impact due to the interaction of breaking waves and an advancing hull surface is expected to be applicable to investigation of the ship bow slamming problem as a specific application.

• 대한조선학회지
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• 제25권4호
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• pp.13-27
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• 1988

TUMMAC차분법(差分法)이 두 가지의 삼차원파(三次元波), 즉 배의 항주(航走)에 따른 파형(波形)과 수직사각주(垂直四角柱) 주위의 쇄파해석(碎波解析)에 적용(適用)되어졌다. Series 60($C_B=0.6$) 모형선(模型船)과 HSVA 모형선(模型船)의 선수부(船首部)에 의한 파형(波形)이 자유표면(自由表面)과 선체후반부(船體後半部)에서의 boundary cell 처리를 엄밀화한 $TUMMAC-IV_{vm1}$방법(方法)에 의하여 계산(計算)되어졌으며, 그 결과가 실제(實際)의 실험결과(實驗結果)들과 비교(比較)되었다. 실험결과(實驗結果)와의 비교를 통하여, $TUMMAC-IV_{vm1}$방법(方法)은 배에 의한 비선형파(非線形波)의 특성해석(特性解析)에 매우 응용성(應用性)이 높음을 보였다. 특히, 비대선형(肥大船型)인 HSVA 모형선(模型船)의 경우는 계산(計算)된 비선형선수파(非線形船首波)의 특성(特性)이 실험결과(實驗結果)와 좋은 일치를 보였다. 수직사각주(垂直四角柱)주위의 쇄파(碎波)를 포함한 심한 비선형파(非線形波)가 삼차원비선형파(三次元非線形波)의 대표적(對表的)인 예(例)로써 TUMMAC-VI 방법(方法)에 의하여 계산(計算)되었다. TUMMAC-VI 방법(方法)은 이층류(二層流)를 함께 푸는 방법(方法)으로, 두가지 유체(流體) 사이의 밀도변화(密度變化), 즉 marker-density를 이용하여 interface를 결정하게 된다. 그러나, 비압축성유체(非壓縮性流體)에 관한 N-S 방정식(方程式)의 해(解)이므로, 그 밖의 계산(計算)에서는 각각의 대표적(對表的)인 밀도(密度)를 사용한다. 계산결과(計算結果)는 삭가주(四角柱) 앞부분의 원형파(圓形波)와 앞어깨에서의 심한 경사를 가지는 파(波), 뒷부분에서의 복잡(複雜)한 쇄파현상(碎波現像)들이 실제의 파특성(波特性)을 잘 나타내어 주었다. TUMMAC-VI 방법(方法)은 interface의 처리를 포함하여 앞으로도 개선(改善)의 여지가 많으며, 단지 공기(空氣)와 물만이 아닌 일반적(一般的)인 이층류(二層流)의 해석에도 폭 넓게 이용될 수 있으리라 본다.