• 천문학회지
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• 제49권1호
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• pp.19-23
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• 2016

Magnetic decreases are often observed in various regions of interplanetary space. Many studies are devoted to reveal the physical nature and generation mechanism of the magnetic decreases, but still we do not fully understand magnetic decreases. In this study, we investigate the structure of a magnetic decrease observed in a corotating interaction region using multi-spacecraft measurements. We use three spacecraft, ACE, Cluster, and Wind, which were widely separated in the x- and y-directions in the geocentric solar ecliptic (GSE) coordinates. The boundaries of the magnetic decrease are the same at the three locations and can be identified as tangential discontinuities. A notable feature is that the magnetic decrease has very large dimension, ≳ R_E, along the boundary, which is much larger than the size, ~ 6 R_E, along the normal direction. This suggests that the magnetic decrease has a shape of a long, thin rod or a wide slab.

• 한국전산유체공학회지
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• 제1권1호
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• pp.26-34
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• 1996

The performance of the SIMPLE, SIMPLE-C and PISO algorithms for the treatment of the pressure-velocity coupling in fluid flow problems were examined by comparing the computational effort required to obtain the same level of the convergence. Example problems are circular duct and 90-degree bent square-duct. For circular duct case, laminar and turbulent flow were computed. For 90-degree bent square-duct case, laminar flow was simulated by the time-marching method as well as the iterative method. The convergence speed of the other two algorithms are not always superior to SIMPLE algorithm. SIMPLE algorithm is faster than SIMPLE-C algorithm in the simple laminar flow calculations. The application of the PISO algorithm in three dimensional general coordinates is not so effective as in two-dimensional ones. Since computational time of PISO algorithm is increased at each time step(or iterative step) in three dimension, the total convergence speed is not decreased. But PISO algorithm is stable for large time step by using time marching method,.

• 대한기계학회논문집A
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• 제20권10호
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• pp.3113-3125
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• 1996

The objective of this study is to develop novel method named mechanical and chemical machining technique, which is capable of producing three dimensional patterns of few micrometers in dimension on a silicon wafer without the use of a mask. The strategy is to impart mechanical energy along the path of the pattern to be fabricated on a single crystal silicon by way on introdusing frictional interaction under controlled conditions. Then, the surface is preferentially etched to reveal the areas that have been mechanically energized. Upon completion of the etching process, the three dimensional pattern is produced on the silicon surface. Experiments have been conducted to identify the optimal tool material, geometery, as well as fabrication condition. The new technique introduced in this paper is significantly simpler than the conventional method which require sophisticated equipment and much time.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.296-299
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• 2001

We developed a motion capture system to get angle data of human joints in the walking mode. The motion capture system is a pair of leg-shape device, which is composed of three links with ankle, knee and pelvis joints. The sensors for measurement of the joint angle are potentiometers. We used an A/D converter to get digital data from joint angles, and which are used to simulate and coordinate the biped-walking robot developed in our laboratory. To simulate and analyze walking motion, animation based on three-dimension motion is performed using the open inventor software.

• Journal of International Society for Simulation Surgery
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• 제4권1호
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• pp.17-20
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• 2017

Purpose Interactive 3D visualization system through remote data transmission over heterogeneous network is growing due to the improvement of internet based real time streaming technology. Materials and Methods The current internet's IP layer has several weaknesses against IP spoofing or IP sniffing type of network attacks since it was developed for reliable packet exchange. In order to compensate the security issues with normal IP layer, we designed a remote medical visualization system, based on Virtual Private Network. Results Particularly in hospital, if there are many surgeons that need to receive the streaming information, too much load on the gateway can results in deficit of processing power and cause the delay. Conclusion End to end security through the network method would be required.

• 한국광학회지
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• 제5권4호
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• pp.439-444
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• 1994

임의의 2차원 표면양각 유전회절격자에 의한 일반적인 회절현상을 엄밀한 3차원벡터 결합파해석으로 다루는데 있어서 핵심적인 역학을 하는 행렬의 고유값문제가 항상 1/4 크기의 행렬에 대한 것으로 단순화되어, 컴퓨터의 계산시간과 기억용량의 요구를 현저히 줄일 수 있다는 것을 보였다. 한편, 체적형 회절격자에 있어서는 이와 같이 단순화할 수 없음을 논의하였다.

• 전자공학회논문지S
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• 제35S권1호
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• pp.80-87
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• 1998

In this study, a multi-element ultrasound transducer has been developed aiming at basic experiment of three-dimension endovascular ultrasound endscopy for clinical diagnos, and experimental results of two-dimensional object imaging in the water are presented by the ultrasound tranducer and neural network. Each ultrasound echo received by thirty-six angular transducer elements is inputed to the eural network, and then backpropagation is used as a learning algorithm. A three-layer artificial neural network is used for learning and imaging of targetw placed in front of the transducer. The object shape of imaging is restricted to rectangular shapes by considering experimental restraint conditions. As a result, rough visualization can be realized even for objects with unlearned shapes through the training by primitive patterns of a various sized rectangular targets.

• 한국전기전자재료학회논문지
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• 제20권3호
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• pp.250-256
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• 2007

We analyzed the effect of a pixel and all the inter-electrode capacitances in a unit pixel of TFT-LCDs on the gray scale capability. The pixel and all the inter-electrode parasitic capacitances were obtained from the tree dimensional profiles of potential distribution and molecular director considering lateral fields generated at the edge of the pixel. To obtain the RMS and kickback voltages of the pixel, we constructed an equivalent circuit of the panel containing all the parasitic capacitances. The calculation was performed though H-SPICE. As results, we confirmed that the pixel becomes smaller, the effect of parasitic capacitances on the gray scale capability becomes larger.

• 경영과학
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• 제19권1호
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• pp.67-75
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• 2002

This paper deals with the visualization method of solutions of the linear programming Problem. We used the revised simplex method for the LP algorithm. To represent the solutions at each iteration, we need the informations of feasible legion and animated effect of solutions. For the visualization in high dimension space, we used the method of Projection to the three dimensions if the decision variable vector is over three dimensions, and we studied the technique of preserving original Polyhedral information such as the number of vertices. In addtion, we studied the method of visualizing unbounded feasible region and the adjacency relationship of the vortices welch is Indispensable to cisualize feasible legion.

• 한국정보처리학회논문지
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• 제7권5호
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• pp.1456-1463
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• 2000

The main objective of this study is to show how to measure the education effectiveness of simulator system in the army. We investigate the education effectiveness through the measuring model that consists of three dimensions such as understanding, experience, and learning. The results of empirical analysis demonstrate that the education effectiveness depends on three dimensions. The result also suggests that the higher the degree of each dimension is, the higher the education effectiveness. However, there is no education effectiveness difference between the traditional training and the simulator training because of the elementary level of simulator function.