• Journal of the Korean Society for Precision Engineering
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• v.17 no.10
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• pp.186-191
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• 2000

We use so many plastic products in everyday. Because polymer materials have a lot of merits including low cost and easiness of forming, they are widely using at many manufacturing industries. Microcellular foaming process appeared at MIT in 1980's to save a quantity of material and increase mechanical properties. The information about the thickness of cavity plays an important role in appling microcellular foaming process to the conventional injection molding process. It is essential to make an effective foam. The goal of this research is to measure the relation between the change of cavity's thickness and foaming magnitude made after inserting a gas. R/t is a conception that indicate proportion between radius and thickness of cavity in mold system. By means of SEM observation of side surface of cavity sample, foaming magnitude of cavity is mold system. By means of SEM observation of side surface of cavity sample, foaming magnitude of polymer in microcellular foaming process is decreasing gradually as the value of R/t is increasing. The proposed foaming magnitude changes data of polymer in relation to mold system can be applied in more extensive injection molding process, such as optimum design of mold for microcellular foaming process.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.9
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• pp.78-85
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• 1998

In this paper we propose a VLSI implementation technique for camcorder's digital zooming system. The proposed VLSI includes the system clock(CLK), vertical drive(VD), horizontal drive(HD),blank(BLK), and field(FLD) signals as inputs, and produces magnified image as an output, with 256 different magnification ratios. In general, the above mentioned input signals are provided by the CCD driving IC in most camcorders. As a result, the proposed digital zooming VLSI can magnify a part of the input image by up to 256 times, where the magnification ratio can be chosen among 256 different steps. In the application point of view, the proposed VLSI can be used in any digital camcorder for realizing near continuous step digital zooming without any additional circuitry, such as micom or a general purpose digital signal processor.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.6
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• pp.351-356
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• 2022

In this paper, we present the regression analysis and design optimization for improving the permeability of 3D woven materials based on numerical analysis data. First, the parametric analysis model is generated with variables that define the gap sizes between each directional wire of the woven material. Then, material properties such as bulk modulus, thermal conductivity coefficient, and permeability are calculated using numerical analysis, and these material data are used in the polynomial-based regression analysis. The Pareto optimal solution is obtained between bulk modulus and permeability by using multi-objective optimization and shows their trade-off relation. In addition, gradient-based design optimization is applied to maximize the fluid permeability for 3D woven materials, and the optimal designs are obtained according to the various minimum bulk modulus constraints. Finally, the optimal solutions from regression equations are verified to demonstrate the accuracy of the proposed method.

• Polymer(Korea)
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• v.25 no.4
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• pp.528-535
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• 2001

Polyurethane specimens were mainly composed of polyol, MDI, silicone surfactant, and water. The effects of ethylene glycol on the cell size, forming magnification, cream time, gel time, take free time, final free rising height, and reactive temperature were investigated. The cyclopentane was used for PU foam as a physical blowing agent. The components were hand-mixed at about 5000 rpm within 4 seconds at room temperature. The mixtures with various ethylene glycol contents were foamed in the wood mold. When the index of isocyanate was fixed, as the amount of ethylene glycol increased, cell size and thermal conductivity were decreased by about 5.1% and 14%, respectively.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.458-461
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• 2009

본 논문에서는 2개의 구조물이 마찰댐퍼로 연결된 연결제진구조물에 대한 지진응답해석을 실시하였다. 연결제진구조물의 지진시의 제진효과를 파악하기 위하여 마찰댐퍼의 복원력특성을 완전탄소성형으로 설정하고 두 구조물의 고유주기 및 연결강성의 변화에 따른 각 지진파별 시간이력지진응답해석을 실시하였다. 또한, 응답해석결과를 바탕으로 마찰댐퍼의 특성지표(연결강성배율 $\alpha$, 항복내력비 $\beta$)를 결정하는 제진성능곡선을 제안하였다. 제진성능곡선을 통한 마찰댐퍼의 특성지표에 근거하여 연결제진구조물에 마찰댐퍼를 효율적으로 사용할 수 있는 최적의 마찰댐퍼량을 결정 할 수 있는 자료를 제시하였다.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.873-876
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• 2001

관상 동맥 질환은 관상 동맥 내벽에 플라크(Plaque)가 침착된 결과 혈관이 좁아져서 생기는 질환으로, 혈관이 좁아져 심장으로의 혈류가 감소하고, 혈전이 동맥을 막아 심장 발작을 일으킨다. 본 논문에서는 관상동맥 질환의 객관적 분석을 위한 분할 방법론과 분할된 영역으로부터 정량적 분석 방법을 제안한다. 동맥 단면영상으로부터 정량 분석을 위해 획득한 단면영상을 현미경으로부터 12.5배 배율로 얻었으며, 정량 분석을 위해 혈관의 각 영역을 분할하여 분할영역의 크기, 최대 장축 등의 정보를 추출하였다. 본 논문에서 제시한 알고리즘을 사용하여 수 작업에 의한 혈관 단면 분석을 자동화하면, 3차원적 변화량에 따른 정량분석 결과를 얻을 수 있을 것이다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.3
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• pp.55-60
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• 2001

In this paper a new algorithm is introduced to enhance the fingerprint image effectively using fuzzy logic. Our approach is not constrained to a particular image size and scale. It rather handle different conditions of noise and image scale. Ridges are thinned while the image is enhanced along the same orientation as the ridges. The problem of false minutia can be also resolved.

• Korean Journal of Optics and Photonics
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• v.6 no.1
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• pp.1-7
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• 1995

A IR zoom telescope system was designed for thermal imagery. The magnification is 4-14 and the focal length of eye piece is 25 mm. First, the frame was built up with first order optics and started design with 3rd order optics. There after, we can get the final design by optimization technique through finite ray tracing. The optical system was optimized with ray aberration or angular aberration including higer orders. Finally, The performance of the optical system was accessed by calculating the diffraction MTF from the design data. data.

• Proceedings of the Korean Geotechical Society Conference
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• 1994.03b
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• pp.47-62
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• 1994

Polyol을 주성분으로 하는 A액과 MDI계 isocyanate로 구성된 B약을 배합비와 배합속도를 각각 1:2에서 1:4까지, 300rpm에서 900rpm까지 변화시키면서 혼합하였다. 생성된 foamed polyurethane은 600rpm의 배합속도에서 배합비가 1:2에서 1:4로 감소함에 따라 발포율이 증가하는 현상을 보였다. 300rpm의 배합속도에서는 거의 발포가 되지 않았음, 900rpm의 배합속도에서는 발포는 되었으나 brittle한 물성을 보였다. 열변형온도 및 하중에 대한 변형율은 600rpm에서 1:2에서 1:3의 배율시 가장 우수한 것으로 관찰되었다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1999.11a
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• pp.438-442
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• 1999

제스처 인식은 직관적일 뿐 아니라, 몇 가지의 기본 구성요소에 의하여 코드화(code)가 용이하여, 인간과 컴퓨터의 상호작용(HCI, Human-Computer Interaction)에 있어서 폭넓게 사용되고 있다. 본 논문에서는 손의 모양이나 크기와 같은 개인차 및 조명의 변화나 배율과 같은 입력환경의 영향을 최소화하여, 특별한 초기화 과정이나 모델의 준비과정 없이도 제스처를 인식할 수 있고, 적은 계산량으로 실시간 인식이 가능한 제스처 인식 시스템의 개발을 목표로 한다. 본 논문에서는 손에 부착하는 센서나 마커 없이, CCD 카메라에 의하여 입력된 컬러영상에서, 컬러정보 및 동작정보를 이용하여 손영역을 추출하고, 추출된 손의 경계선 정보를 이용하여 경계선-중심 거리 함수를 생성했다. 그리고, 손가락의 끝 부분에서는 경계선-중심 거리가 극대점을 이룬다는 원리를 이용하여 생성된 함수의 주파수를 분석하여 극대점을 구함으로써 각각의 손가락 끝 위치를 찾고, 손의 자세를 인식하여 제스처를 인식했다. 또한 본 논문에서 제안된 제스처 인식 방법은 PC상에서 구현되어 그 유용성과 실효성이 증명되었다.