• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1057-1058
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• 2011

This paper deals with finding the optimal ratio of height and length of Single-Sided Linear Induction Motors (SLIM) using Finite Element Method (FEM) for magnetic field analysis coupled with optimal design methodology. For effective analysis, FEM is conducted in time harmonic field which provides steady state performance with the fundamental components of voltage and current. The ratio of height to length providing the required output power is obtained by Response Surface Methodology (RSM) and optimal values are presented by the variation in output power. When output power is small, the ratio is high and as the power increases, the ratio shows a converged value. Considering the general application of linear motors, using a small ratio can be limiting, however, the shape ratio for maximum thrust can be identified.

• 전산구조공학
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• 제3권3호
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• pp.133-140
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• 1990

케이블 구조물은 응력-변형도관계에서 비선형성이 강하고 대변위에 의해 기하학적 비선형이 도입되므로 해석이 복잡하다. 그러므로 케이블 구조물의 평형형태 탐색과 해석에 앞서 기하학적 비선형을 고려해야만 한다. 본 논문에서는 이러한 문제를 해결하기 위해 케이블, 네트, 전선, 현수케이블 지붕등에 적용될 수 있는 수치해석과정이 소개된다. 이 과정은 두 부분으로 나눌 수 있는데, 하나는 유연성반복과정에의해 등분포하중을 받는 케이블 구조물의 응력과 평형형태를 구하는 것이고, 다른 한 부분은 비선형 유한요소법에 의해 절점외력을 받는 평형형태를 해석하는 것이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.1205-1205
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• 2003

Rotary compressors are one of the most important parts of air-conditioners in the industry This device usually has noise problems during the circulation process of the refrigerant and muffler is used for the noise reduction. The acoustic performance of the muffler depends on its shape and its hole locations on the upper surface. Therefore finding the optimum location of the muffler holes is a topic of increasing importance in the compressor industry. In this research the optimization of the muffler hole locations and the importance of the resonator cavity on the lower surface of the muffler in acoustic point of view is studied. At first, the topology optimization for the 2 hole muffler is performed based on a model without resonator cavity by using genetic algorithm. The 2 hole muffler's acoustic analysis and experiment results are matching, however, the optimized model's results are not. By adding the resonator cavity and also by changing the cavity shape, the acoustic analysis and experiment result comparison is Performed for different cavity shapes. The topology optimization of the revised model with cavity is carried out for noise reduction. Finally, the optimized design is produced and tested for validation.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제21권3호
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• pp.25-35
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• 2015

Purpose: Signs that are installed at unnoticeable places or that disconnect before the destination can bring errors of location information delivery. Therefore, this study aims to find out the spatial relation between structure of space and signs in the perspective of visual exposure possibility, operating arrangement and assesment by applying spatial structure theory. Methods: Effectiveness of organization of guidance signs was evaluated after the four way-finding factors(Plan Configuration, Sign System, Perceptual Access, Architectural Difference) that G.D.Weisman suggested were interpreted by spatial structure theory(J-Graph analysis, Space Syntax, Visual Graph Analysis) under the premise that it is closely related to the structure of space. Results: 1) Because the south corridor that connects each department of outpatient division is located in the hierarchy center of the space, and walking density is expected to be high, guidance signs need to be organized at the place with high integration value. 2) The depth to the destination space can be estimated through J-Graph analysis. The depth means a switch of direction, and the guidance signs are needed according to the number. 3) According to visibility graph analysis, visual exposure can be different in the same hierarchy unit space according to the shape of the flat surface. Based on these data, location adjustment of signs is possible, and the improvement effect can be estimated quantitatively. Implications: Spatial structure theory can be utilized to design and evaluate sign systems, and it helps to clearly understand the improvement effect. It is desirable to specify design and estimation of sign systems in the order of J-Graph analysis${\rightarrow}$Space Syntax Theory${\rightarrow}$visibility graph analysis.

• 전자공학회논문지SC
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• 제42권5호
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• pp.19-26
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• 2005

본 논문에서는 CCD 카메라를 이용하여 획득된 영상들 간의 상대적인 열화(Blur)를 이용하여 물체의 3차원 형상 및 거리 정보를 얻을 수 있는 Depth From Defocus(DFD) 방법을 제안한다. 기존 논문의 주파수 영역에서 디포커스(Defocus) 연산자를 구하는 역필터링(Inverse filtering) 방법은 정확도가 떨어지고, 윈도우 효과(Windowing effects) 및 영상의 경계 효과(Border effect)와 같은 단점이 있었다. 또한 일반적인 영상은 비정체성 (Nonstationary)이기 때문에, 임의의 텍스처에 대한 가우시안(Gaussian) 및 라플라시안(Laplacian) 연산자 등의 필터를 이용하는 디포커스 방법의 추정값은 결과가 좋지 않다. 이러한 문제점들을 해결하기 위해 지역적 분석과 함께 다양한 크기의 윈도우를 제공하는 웨이블릿 변환을 이용한 DFD 방법을 제안한다. 복잡한 텍스처 특성을 갖는 영상의 깊이 추정을 위해서는 웨이블릿 분석을 사용하는 것이 효과적이다. Parseval의 정리에 의해 영상 간의 웨이블릿 에너지의 비율이 열화 계수(Blur parameter) 및 거리와 관련 있음을 증명하였다. 제안된 DFD 알고리즘의 성능을 계산하기 위해 실험은 종합적이며 실제적인 영상을 이용하여 행하였다. 본 논문의 DFD 방식은 기존의 DFD 방법보다 RMS 에러 측면에서 정확한 결과를 보였다.

• 한국물환경학회지
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• 제24권6호
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• pp.793-800
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• 2008

Recently domestic drinking water industry has recognized membrane-based technology as a promising alternative for water treatment. To ensure successful application of membrane processes, the integrity of membrane systems should be maintained. According to US EPA guidance, the pressure decay test based on the bubble point theory is recommended to detect any membrane defection of which size is close to the smallest diameter of Cryptosporidium oocysts, $3{\mu}m$. Proper implementation of the pressure decay test is greatly affected by initial test pressure, and the interpretation of the test results is associated with upper control limit. This study is conducted to investigate various factors affecting determination of initial test prtessure and upper control limit, including membrane-based parameters such as pore shape correction factor, surface tension and contact angle, and system-based parameters, such as volumetric concentration factor and total volume of system. In this paper, three different hollow fibers were used to perform the pressure decay test. With identical initial test pressure applied, their pressure decay tendency were different from each other. This finding can be explained by the micro-structure disparity of those membranes which is verified by FESEM images of those membranes. More specifically, FESEM images revealed that three hollow fibers have asymmetry, deep finger, shallow finger pore shape, respectively. In addition, sensitivity analysis was conducted on five parameters mentioned above to elucidate their relation to determination of initial test pressure and upper control limit. In case of initial pressure calculation, the pore shape correction factor has the highest value of sensitivity. For upper control limit determination, system factors have greater impact compared to membrane-based parameters.

• 대한간호학회지
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• 제43권3호
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• pp.431-441
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• 2013

Purpose: The study was done to explore meanings and essence of the experience in South Korea of men defectors from North Korea. Methods: Data were collected from March, 2011 to May, 2012, through in-depth interviews with ten men defectors. Data analysis was conducted using the process of hermeneutic phenomenological reflection. Results: Eight essential themes were extracted; 'buoyant expectation for a new life', 'feeling guilty about family left behind in North Korea', 'inability to become acclimatized due to communication difficulties', 'inability to socialize with South Koreans due to different lifestyles', 'finding strength through trustworthy acquaintances', 'continuing reconciliation with oneself while trying to assimilate into South Korean culture', 'self-realization of one's original self', and 'continuing to feel out the possibility of a future in South Korea'. Conclusion: The findings indicate that North Korean men who defect to South Korea shape their identity through three phases: forming self-image during escape from North Korea, trying to become accustomed to South Korean society, and finding their own identity by self-realization of their original self. Eventually, the whole process enables them to recover their identity, to feel a sense of belonging, and to discover possibilities for a better future.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.325-332
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• 2006

Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation, because the material property has strong axial stiffness, but little bending stiffness. The problem of cutting pattern is highly varied in their size, curvature and material stiffness. So, the approximation inherent in cutting pattern generation methods is quite different. Therefore the ordinary computer software of structural analysis & design is not suitable for membrane structures. In this study, we develop the program for cutting pattern generation using geodesic line, and investigate the result of example's cutting pattern in detail.

• 한국공간구조학회논문집
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• 제5권2호
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• pp.81-87
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• 2005

The Space structures may have large freedom in scale and form. And especially Hybrid structures are received much attention from the view points of their light weight and aesthetics. Hybrid systems are stable structures which are reticulated spatial structures composed of compressive straight members, struts and cables and Membranes. In this paper, The Hybrid Unit System are suggested using the Membrane and Cable elements based on the Tensegrity Unit system. Also, The Hybrid System of double-layered single curvature is presented. We analyze the force density method allowing form-finding for Tensegrity systems. And We analyze the shape analysis by the LARSH which is the program for nonlinear analysis.

• 대한기계학회논문집
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• 제13권1호
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• pp.20-28
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• 1989

본 연구에서는 경계조건에 대한 음향 방사율을 계산하고, 또한 각각의 구조물을 가진하여 진동을 측정하여 음향 방사 파워를 예측한다.