• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.8
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• pp.107-118
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• 1995

Three-dimensional simulator for thermal oxidation process is developed. The simulator is consisted by two individual module, one is analytic-model module and the other is numerical-model module. The analytic-model which uses simple complementary-error function guarantees fast calculation in prediction of multi-dimensional oxidation process. The numerical-model which is based on boundary element method (BEM), has a good accuracy and suitable for various process conditions. The results of this study show that oxide growth is retarded at the corner of hole structure and enhanced at the corner of island structure. These effects are reson of different distribution of oxidant diffusion and mask stress. The utility of models and simulator developed in this study is demonstrated by using it to predict not only traditional shape of LOCOS but also process effects in small geometry.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.650-652
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• 1998

본 논문은 mesh 간략화를 위한 새로운 Gaussian 곡률 오차 추정 방법을 제안한다. Gaussian 곡률은 임의의 형상을 갖는 삼각화 된 단면체 표면에 대하여 위상과 기하학적 정보를 angle 과 face 의 관계로 정형화하여, vertex에 관한 곡률로 근사하여 표현한다. 간략화 방법은 지역적 형상으로부터 전체적인 형상을 추정한 후, 적절한 curvature criteria 로 간략화가 될 vertex를 선택하고 제거한다. 제거된 vertex에 의해 생성된 hole은 곡률에 기반하여 삼각화하고 곡률이 변화되는 vertex들의 Gaussian 곡률 오차를 계산한다. 각 간략화 level마다 최대 Gaussian 곡률 오차를 계산하므로, 사용자는 Gaussian 곡률 오차 추정으로 원하는 간략화 level을 지정할 수 있다. 또한 주어진 오차 안에서 vertex뿐만 아니라 edge나 face의 제거로, 간략화 되는 영역을 확산시켜 필요한 위상과 기하학적 정보를 유지하는 간략화를 할 수 있다.

• 전자공학회논문지 IE
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• v.44 no.1
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• pp.10-14
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• 2007

Analytical expression for breakdown voltages of InP diodes is induced by employing the effective ionization coefficient extracted from ionization coefficients for electron and hole in InP. The analytical results for breakdown voltage are compared with numerical and experimental results for the doping concentration, $N_D=6\times10^{14}cm^{-3}\sim3\times10^{17}cm^{-3}$. The analytical results show good agreement with the numerical data. Good fits with the experimental results are found for the breakdown voltages within 10% in error at each doping concentration.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.169-172
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• 2015

영상회의 장치에서 눈맞춤 영상을 생성하기 위해 어파인 변환(affine transformation)을 이용하면 반올림 오차(round-off error) 때문에 홀이 발생한다. 이러한 홀을 채우려면 홀 영역을 가리키는 홀 채움 마스크가 필요하다. 홀 채움은 보통 홀 채움 마스크를 참조하여 홀이 아닌 이웃 화소값들을 기반으로 손상된 영상을 복원하는 작업이다. 따라서 홀 영역을 정확히 검출하고 적당한 개수의 이웃 화소값을 참조해야 자연스러운 홀 채움 영상을 생성할 수 있다. 한편, 눈맞춤 영상을 생성할 때 얼굴 특징점을 이용해 얼굴 변환 마스크를 만들고, 얼굴 변환 마스크에만 어파인 변환을 수행한다. 이 논문에서는 얼굴 특징점에도 어파인 변환을 수행하고 수정된 얼굴 변환 마스크를 획득하여 정확한 홀 채움 마스크를 구한다. 또한, 홀 채움 마스크에서 레이블링을 수행하여 큰 홀 영역을 제거한다. 마지막으로, 어파인 변환을 수행할 때 기존 영상의 좌표값을 이용하여 자연스러운 홀 채움 영상을 생성한다. 제안하는 방법으로 홀 채움을 수행한 결과, 연속적인 눈맞춤 동영상에서 이웃값들을 참조하여 홀 채움을 수행한 영상보다 자연스러움을 확인했다.

• Structural Engineering and Mechanics
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• v.57 no.2
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• pp.281-294
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• 2016

The paper is devoted to study a mesh-free analysis method of structural elements of engineering structures based on B-spline Wavelet Basis Function. First, by employing the moving-least square method and the weighted residual method to solve the structural displacement field, the control equations and the stiffness equations are obtained. And then constructs the displacement field of the structure by using the m-order B-spline wavelet basis function as a weight function. In the end, the paper selects the plane beam structure and the structure with opening hole to carry out numerical analysis of deformation and stress. The Finite Element Method calculation results are compared with the results of the method proposed, and the calculation results of the relative error norm is compared with Gauss weight function as weight function. Therefore, the clarification verified the validity and accuracy of the proposed method.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.58-64
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• 2008

The cutting process of materials is accompanied with the elastic and plastic deformation due to chucking forces in the boring process of thin holes on the turning. Upon removal of chucking forces at the end of process, the original shape is remained in the plastic deformation; on the other hand, it is modified in the elastic deformation due to spring back. Fixing materials by chucks on the turning has influence on roundness because the process is conducted with unbalanced distribution load induced from the fixing of three jaws. Moreover, the amount of spring back depends on the magnitude of fixing forces. We studied the change of roundness according to fixing forces as well as the method to reduce the influence of chucking forces.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.3
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• pp.42-48
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• 1996

In this paper, a position correction system of industrial robot for door-chassis assembly tast is developed in connection with the position correction algorithm shown in Part I. Tow notches and a hole of auto chassis are selected as the reference measure points and a vision based error detection algorithm is devised to measure in accuracy of less than 0.07mm. And also, the transformation between base and tool coordinates of the robot is shown to send the suitable correction quantities caaording to robot's option. The obtained algorithms were satisfactorily implemented for a real door-chassis model such that the system could accomplish visually acceptable door-chassis assembly task.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.79-85
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• 2004

We report on a transmittance controlled photomask with phase patterns on the back quartz surface. Theoretical analysis for changes in illumination pupil shape with respect to the variation of size and density of backside phase patterns and experimental results for improvement of critical dimension uniformity on a wafer by using the transmittance controlled photomask are presented. As phase patterns for controlling transmittance of the photomask we used etched contact-hole type patterns with 180" rotative phase with respect to the unetched region. It is shown that pattern size on the backside of the photomask must be made as small as possible in order to keep the illumination pupil shape as close as possible to the original pupil shape and to achieve as large an illumination intensity drop as possible at a same pattern density. The distribution of illumination intensity drop suitable for correcting critical dimension error was realized by controlling pattern density of the contact-hole type phase patterns. We applied this transmittance controlled photomask to a critical layer of DRAM (Dynamic Random Access Memory) having a 140nm design rule and could achieve improvement of the critical dimension uniformity value from 24.0 nm to 10.7 nm in 3$\sigma$.TEX>.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.1
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• pp.41-48
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• 1986

Ifis recommended that the injection rate should be accurate and reliable in the input data of the performance simulation in diesel engine. Matsuoka Sin improved W. Bosch's injection ratio measurement system. Matsuoka Sin reduced length of the test pipe and set the orifice. However, it was not measured accurately to measure the injection ratio due to reflection wave. In the present thesis, the improved measurement system with combination of the conventional W. Bosch type injection ratio measurement system and Matsuoka Sin type corrected W. Bosch type was practically made. The location of orifice and throttle valve was modified and set one more back pressure valve in order to reduce the effect of reflection wave. The results according to injection condition of multi-hole nozzle are following: 1. Measurement error of injection ratio measurement system in this thesis was $\pm$ 1 %, therefore, its reliability was good. 2. The form of injetion ratio is changed from trapezoidal shape to triangle shape with increase of revolution per minute when injection amount is constant. 3. In the case of constant rpm, the initial injection ratio is almost constant regardless of the amount, meanwhile the injection period becomes longer with increase of the amount. 4. The injection pressure of nozzle isn't largely influenced with injection ratio in the case of constant injection amount and rpm, otherwise the initial injection amount is increased by 3-4% when the injection pressure is low. 5. The injection ratio isn't nearly influenced with back pressure.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.683-690
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• 2008

When steel fabricators erect structural members in field, temporary tightening of fastener should be useful. However, if bolt holes are not aligned by production error or natural condition, additional effort andpain should be provided to align bolt holes. It lead to longer period than times of construction (a primarily day of construction) and more cost than originally cost. This problem will be overcomed by oversize or slotted holes. Early, AISC and Eurocode have included provision for design process such oversize or slotted holes. But, domestic design method is not refered about oversize and slotted holes. Meanwhile, domestic design method and construction environment are variance with Europe and the United States of America. Therefore, a suitable design method for oversize and slotted holes in domestic real condition is needed. In this study, we evaluated behavior of the joints and decided the friction coefficient on oversize and slotted holes of friction joints with high strength bolts.