• 한국정밀공학회지
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• 제20권8호
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• pp.126-134
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• 2003

In this study we do for the thing to develop automatic geometry design program of a mechanical element that we have used in CAD/CAM system. The program, which produces automatically three-dimensional surface and a solid model that have been used in CAD/CAM system, widely create automated two and three-dimensional model to by inputting several necessaries for a design, fur the design element. It is emphasized if you are just a beginner having only basic knowledge of the mechanical engineering, you might be able to design easily a three-dimensional model. The software to be used to develop automatic geometry design program is visualLISP to be a developer program of AutoCAD.

• 산업기술연구
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• 제26권B호
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• pp.221-226
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• 2006

Electrical impedance tomography (EIT) is a technique for determining the electrical conductivity and permittivity distribution within the interior of a body from measurements made on its surface. One recent application area of the EIT is the detection of breast cancer by imaging the conductivity and permittivity distribution inside the breast. The present "gold standard" for breast cancer detection is X-ray mammography, and it is desirable that EIT and X-ray mammography use the same geometry. This paper presents a forward model of a simplified mammography geometry for EIT imaging. The mammography geometry is modeled as a rectangular box with electrode arrays on the top and bottom planes. A forward model for the electrical impedance imaging problem is derived for a homogeneous conductivity distribution and Validated by experiment using a phantom tank.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.361-363
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• 1995

High quality $Y_1Ba_2Cu_3O_{7-x}$ thin films have been fabricated by pulsed Nd:YAG laser deposition using an unusual 'off-axis' target-substrate geometry. Various properties of superconducting $Y_1Ba_2Cu_3O_{7-x}$ thin films have been studied systematically as a function of oxygen pressure during the deposition, in both 'on-axis' and the unusual 'off-axis' target substrate geometry. In the 'off-axis' geometry, one can completely eliminate the so-called 'laser droplets' form the thin surface and thus obtain smooth high qualify films. It is found that films with optimum structural and electrical properties are obtained at a lower oxygen pressure range during the 'off-axis' deposition when compared with that required in the 'on-axis' deposition geometry.

• 대한기계학회논문집A
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• 제38권11호
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• pp.1207-1214
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• 2014

균열이 존재하는 구조물의 균열 선단에서 과도한 소성 상태에 도달하게 되면 파괴역학 매개변수에 의하여 예측되는 균열 선단의 응력장이 실제와는 매우 다르게 나타난다. 구조물의 크기와 형상 그리고 하중의 형태에 따라 균열 선단의 응력장이 유일하지 않다. 이는 균열 선단의 구속 효과가 단일 매개변수 파괴역학으로 표현 될 수 없기 때문이다. 따라서 전통적으로 사용되었던 K, J를 이용한 단일 매개변수 파괴역학을 보완하기 위하여 다양한 시도가 있었고, 대표적으로 Q-응력이 있다. 본 논문에서는 Q-응력을 이용하여 원주방향으로 완전히 발달한 표면 균열이 있을 경우의 균열 선단의 구속 효과를 확인하였다. 고려된 하중은 일차하중으로 축 방향 인장하중과 반경방향 열구배에 의한 이차하중의 복합하중이다. 이차하중이 일차하중보다 구속효과가 더 심하며 기계하중보다 열하중이 뒤에 가해지는 열충격조건에서 구속효과가 더 심하게 나타남을 확인하였다.

• 한국진공학회지
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• 제10권1호
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• pp.93-97
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• 2001

본 논문에서는 방사광 X선을 이용하여 표면의 원자구조를 연구하기 위하여 국내 최초로 제작된 초고진공 X-선 산란 장치의 구조 및 성능을 소개한다. 초고진공 X-선 산란 장치는 초고진공에서의 표면처리를 위한 진공부분과 S2D2 geometry를 이용한 수평수직 X-선 회절기로 구성되어 있다. 본 장치의 성능은 Si(111) 표면의 7$\times$7 reconstruction 구조를 관찰함으로서 시연되었다. 본 장치를 이용하여 약 1600$\AA$ 이상의 7$\times$7 도메인으로부터 초당 216 counts의 $(1,{\frac{3}{7}})$ 피크가 관측되었고, 이것으로 본 장치의 진공도와 X-선 회절기의 기능이 표면원자구조를 연구하기에 적합함을 확인할 수 있었다

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.101-106
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• 2006

The geoidal undulations are needed for determining the orthometric heights from the Global Positioning System GPS-derived ellipsoidal heights. There are several methods for geoidal undulation determination. The paper presents a method employing a simple architecture Two Layer Multiquadric-Biharmonic Artificial Neural Network (TLMB-ANN) to approximate an area of 4200 square kilometres quasigeoid surface with GPS-levelling data. Hardy’s Multiquadric-Biharmonic functions is used as the hidden layer neurons’ activation function and Levenberg-Marquardt algorithm is used to train the artificial neural network. In numerical examples five surfaces were compared: the gravimetric geometry hybrid quasigeoid, Support Vector Machine (SVM) model, Hybrid Fuzzy Neural Network (HFNN) model, Traditional Three Layer Artificial Neural Network (ANN) with tanh activation function and TLMB-ANN surface approximation. The effectiveness of TLMB-ANN surface approximation depends on the number of control points. If the number of well-distributed control points is sufficiently large, the results are similar with those obtained by gravity and geometry hybrid method. Importantly, TLMB-ANN surface approximation model possesses good extrapolation performance with high precision.

• Bulletin of the Korean Chemical Society
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• 제14권2호
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• pp.244-250
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• 1993

The interaction of 1,3,5-trithian molecule with Ag(111) surface is studied employing Extended Huckel method. The Ag(111) surface is modeled by the three layer metal clusters composed of 43 Ag atoms. We assume that the 1,3,5-trithian is lying flat on Ag(111) surface in the chair conformation. The geometry of 1,3,5-trithian itself is assumed to be the same as in the gas phase, which is obtained through the AM1 SCF-MO calculation with full geometry optimization. The calculation for 3-fold site adsorption leads to the weakening of C-S bond, which is compatible with the observed 5 cm$^{-1}$ decrease of the C-S stretching frequency upon surface adsorption, while the on-top site adsorption leads to strengthening of C-S bond. The major component of the C-S bond of trithian is S $3p_{pi}\;(S\;3p_x+S\;3p_y)$ and therefore only the 3-fold site adsorption causes the weakening of this bond. In addition, it is found that the trithian molecule binds to the 3-fold site more strongly.

• 한국기계연구소 소보
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• 통권19호
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• pp.163-169
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• 1989

Many computer programs are being developed to aid the design of physical models. These efforts highlight the importance of computer model of three dimensional object. In this paper a CAD application program is introduced which can be implemented to modeling some part that composed with 3 types of surface form ; free form surface, fillt surface, surface of revolution, and a geometry description language which can represent a shape efficiently is preseneted.

• 한국전자파학회논문지
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• 제10권3호
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• pp.359-367
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• 1999

평행평판 도파관으로부터 급전되어지는 주름진 도체판을 가지는 표면파 안테나의 해석이 고려되어진다. 해석의 단순함을 위해 원래의 문제를 3개의 영역, 즉 단락된 평행평판 도파관 내부 구조(내부 영역 1)와 주름진 격자 내부의 구조(내부 영역 2)와 도체 쇄기의 구조(외부 영역)로 나누기 위해 등가원리가 도입된다. End-fire 복사를 하는 주름진 표면과 안테나를 해석하기 위하여 하이브리드 MOM/UTD 방법이 적용되어진다. 수치해석 결과들은 이전의 실험결과들과 매우 잘 일치하며, 이전의 단순 등가전류 접근의 결과들과 비교할 때 더 나은 결과들이 얻어진다. 또한 효과적인 end-fire 주름진 표면파 안테나 설계를 위한 인자들을 얻을 수 있다.

• 설비공학논문집
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• 제23권12호
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• pp.805-814
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• 2011

In the present study, the detailed flow structure and heat transfer characteristics in the newly-designed heat transfer surface geometry were investigated. The surface geometry proposed in the present study is a traditional dimple structure combining with a protrusion inside the dimple, which is named a protrusion-in-dimple in this study. The basic idea underlying the present surface geometry is to enhance the flow mixing and the corresponding heat transfer in the flow re-circulating region generated by a conventional dimple cavity. The present study was performed by the direct numerical simulation at a Reynolds number of 2800 based on mean velocity and channel height and Prandtl number of 0.71. Three different protrusion heights for protrusion-in-dimples were considered as the main design parameter of the present study. The calculated pressure drop and heat transfer capacity were assessed in terms of the Fanning friction factor and Colburn j factor. The overall performances estimated in terms of the volume and area goodness factor for protrusion-in-dimple cases were higher than the conventional dimple case.