• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.2
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• pp.153-162
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• 2012

In this paper, we propose a new shape similarity measure for M:N polygon pairs regardless of different object cardinalities in the pairs. The proposed method compares the projections of two shape functions onto Zernike polynomial basis functions, where the shape functions were obtained from each overall region of objects, thus not being affected by the cardinalities of object pairs. Moments with low-order basis functions describe global shape properties and those with high-order basis functions describe local shape properties. Therefore several moments up to a certain order where the original shapes were similarly reconstructed can efficiently describe the shape properties thus be used for shape comparison. The proposed method was applied for the building objects in the New address digital map and a car navigation map of Seoul area. Comparing to an overlapping ratio method, the proposed method's similarity is more robust to object cardinality.

• The KIPS Transactions:PartA
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• v.11A no.4
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• pp.267-276
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• 2004

The modeling methods of routing region used in the automatic placement/routing system are a grid and non-grid. Because the gird method is curbed by its size and a board if the electrical and physical elements on PCB are of small quantity, it has many memories. Therefore, it has demerit which decreases the speed of automatic placement/routing. The Shape-based type, non-grid method, makes the shapes exist as an in dividual element in a memory by using a region-processing method. Each individual element needs very small memory since it has its unique data size. Therefore, this paper aimed to develope the automatic placement/routing system which can automatically place and route the PCB without dissipation of memory at a high speed. To this aim, the auction algorithm method was applied which can make the memories be most rapidly reached from the original point to various destinations. Also, this system was developed by the Visual C++ in the Widows environment of IBM Pentium computer in order to use it in an individual PC system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.863-871
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• 2013

Flow characteristics of velocity-control trim in a valve is investigated numerically with high pressure drop. A basic trim widely used for a valve in domestic powerplants is selected and designed for a baseline of velocity-control trim. The numerical analysis is focused on flow rate and cavitation with the basic trim. For a condition of high-pressure drop, pressure drop between inlet and outlet and fluid temperature are selected to be 18.1 MPa and $160^{\circ}C$, respectively, which are typical ones considering operating conditions adopted in powerplants. With this baseline model and condition, design changes are made for improvement of flow rate and cavitation phenomenon. For re-design, trim is divided into three zones in radial direction and design parameters of flow area, stage, and flow direction are considered in each zone. With these combined parameters applied to each zone, 4 models with design changes are proposed and their flow rates and cavitation areas are investigated. From comparison with those in the baseline model of a basic trim, proposed models show better performance in both flow rate and cavitation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.11
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• pp.999-1007
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• 2013

The present work reports numerical results of the pressure drop and heat transfer characteristics of pipes with various shapes such as circular, elliptical, circumferential wavy and twisted using a three-dimensional simulation. Numerical simulations are calculated for laminar to turbulent flows. The fully developed flow in pipes was modeled using steady incompressible Reynolds-averaged Navier-Stokes (RANS) equations. The friction and Colburn factor of each pipe are compared with those of a circular tube. The overall flow and heat transfer calculations are evaluated by the volume and area goodness factor. Finally, the objective of the investigation is to find a pipe shape that decreases the pressure loss and increases the heat transfer coefficient.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.549-558
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• 2012

A topology optimization method for phononic crystals is developed for the design of sound barriers, using the level set approach. Given a frequency and an incident wave to the phononic crystals, an optimal shape of periodic inclusions is found by minimizing the norm of transmittance. In a sound field including scattering bodies, an acoustic wave can be refracted on the obstacle boundaries, which enables to control acoustic performance by taking the shape of inclusions as the design variables. In this research, we consider a layered structure which is composed of inclusions arranged periodically in horizontal direction while finite inclusions are distributed in vertical direction. Due to the periodicity of inclusions, a unit cell can be considered to analyze the wave propagation together with proper boundary conditions which are imposed on the left and right edges of the unit cell using the Bloch theorem. The boundary conditions for the lower and the upper boundaries of unit cell are described by impedance matrices, which represent the transmission of waves between the layered structure and the semi-infinite external media. A level set method is employed to describe the topology and the shape of inclusions. In the level set method, the initial domain is kept fixed and its boundary is represented by an implicit moving boundary embedded in the level set function, which facilitates to handle complicated topological shape changes. Through several numerical examples, the applicability of the proposed method is demonstrated.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.207-209
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• 2000

GDI(Gasoline Direct Injection) 기관은 전체적으로 희박한 영역에서 작동되기 때문에 저연비, 고출력화 및 배기유해가스 저감에 매우 유리하다. GDI 기관에 있어서 희박연소를 실현하고자 한 연구는 공기유동 강화방식, 연소실 형상의 최적화, 부실식 연소, 분사된 연료의 미립화, 흡기포트의 형상 변화, 운전조건 변화에 따른 분사전략의 변화 등 그 방식도 다양하며,$^{<1-5>}$ 최근엔 이러한 각 방식들의 장점들을 적절히 활용하고 이에 따라 각기 고유한 모델을 채택하여 접근하려는 시도를 하고 있다$^{<6>}$ . (중략)

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.203-208
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• 2000

2진 로봇 머니퓰레이터는 기하학적 형상이 가변트러스 구조로 되어 있으며 조인트의 구동원으로 사용되는 엑츄에이터는 2가지의 변위, 즉 최대 및 최소 변위만으로 동작한다. 따라서 작업영역은 연속적으로 주어지는 일반 로봇 머니퓰레이터와는 달리 유한 개의 위치 벡터의 집합 형태로 나타난다. 기존의 역기구학적 해석방법을 적용하기 어려운 2진 로봇 머니퓰레이터의 불연속적인 특성에 대해 새로운 작업영역과 역기구학 문제를 정의하였다. 유전 알고리즘을 사용하여 새로이 정의된 문제의 역기구학적 해석을 수행하였으며 유전 알고리즘이 2진 로봇 머니퓰레이터의 역기구학적 해석에 있어서 효과적이고 강건한 방법임을 보여주었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.1
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• pp.54-62
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• 2017

For the Earth observation satellite for ISR mission, a satellite constellation can be utilized to observe a specific area periodically and ultimately increase the effectiveness of the mission. The Walker-Delta method was applied to design constellation orbits with four satellites, which could detect abnormal activities in AoI(Area of Interest). To evaluate the effectiveness of the mission, a revisiting time was selected as a key requirement. This paper presents the mission analysis process for four SAR satellites constellation as well as the result of constellation configuration design to meet the requirements. Figure of Merits analysis was performed based on algorithm developed. Finally, it was confirmed that the constellation orbit with four different orbital planes is likely to be appropriate for ISR mission.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.469-476
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• 2007

A domain/boundary decomposition technique is applied to carry out efficient finite element analyses of 3-D contact problems. Appropriate penalty functions are selected for connecting an interface and contact interfaces with neighboring subdomains that satisfy continuity constraints. As a consequence, all the effective stiffness matrices have positive definiteness, and computational efficiency can be improved to a considerable degree. If necessary, any complex-shaped 3-D domain can be divided into several simple-shaped subdomains without considering the conformity of meshes along the interface. With a set of numerical examples, the basic characteristics of computational efficiency are investigated carefully.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.897-902
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• 2007

인간과 컴퓨터간의 전통적인 인터페이스는 인간이 요구하는 다양한 인터페이스를 제공하지 못한다는 점에서 점차 사용하기 불편하게 되었고 이는 새로운 형태의 인터페이스에 대한 요구로 이어지게 되었다. 본 논문에서는 이러한 추세에 맞추어 카메라를 통해 인간의 손 제스처를 인식하는 새로운 인터페이스를 연구하였다. 손은 자유도가 높고 3차원의 view direction에 의해 형상이 매우 심하게 변한다. 따라서 윤곽선 기반방법과 같은 2차원으로 투영된 영상에서 contour나 edge의 정보로 손 제스처를 인식하는 데는 한계가 있다. 그러나 모델기반 방법은 3차원 정보를 이용하기 때문에 손 제스처를 인식하는데 좋으나 계산량이 많아 실시간으로 처리하기가 쉽지 않다. 이러한 문제점을 해결하기 위해 손 형상에 대한 대규모 데이터베이스를 구성하고 정규화된 공간에서 Feature 간의 연관성을 파악하여 훈련 데이터 모델을 구성하여 비교함으로써 실시간으로 손 포즈를 구별할 수 있다. 이러한 통계적 학습 기반의 알고리즘은 다양한 데이터와 좋은 feature의 검출이 최적의 성능을 구현하는 것과 연관된다. 따라서 배경으로부터 노이즈를 최대한 줄이기 위해 피부의 색상 정보를 이용하여 손 후보 영역을 검출하고 검출된 후보 영역으로부터 HLF(Haar-like Feature)를 이용하여 손 영역을 검출한다. 검출된 손 영역으로부터 패턴 분류 과정을 거쳐 손 포즈를 인식 하게 된다. 패턴 분류 과정은 HLF를 이용하여 손 포즈를 인식하게 되는데 미리 학습된 각 포즈에 대한 HLF를 이용하여 손 포즈를 인식하게 된다. HLF는 Violar가 얼굴 검출에 적용한 것으로 얼굴 검출에 좋은 결과를 보여 주었으며, 이는 적분 이미지로부터 추출한 HLF를 이용한 Adaboost 학습 알고리즘을 사용하였다. 본 논문에서는 피부색의 색상 정보를 이용 배경과 손 영상을 최대한 분리하여 배경의 대부분이 Adaboost-Haar Classifier의 첫 번째 스테이지에서 제거되는 방법을 이용하여 그 성능을 더 향상 시켜 손 형상 인식에 적용하였다.