• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1999년도 학술대회
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• pp.9-14
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• 1999

The object boundary of an image plays an important role for image interpretation. In this paper, we introduce a concept of hierarchical mesh-based image segmentation for finding object boundaries. In each hierarchical layer, we employ neighborhood searching and boundary tracking methods to refine the initial boundary estimate. We also apply a local region growing method to define closed contours. Experimental results indicate that reliable segmentation of objects can be accomplished by the pro-posed tow complexity technique.

• 한국CDE학회논문집
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• 제6권2호
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• pp.89-100
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• 2001

Swept volume is the sweeping region of moving objects. It is used in various applications such as interference detection in assembly design, visualization of manipulator motions in robotics, simulation of the volume removal by a cutter in NC machining. The shape of swept volume is defined by the envelope, which is determined by the boundary of moving objects and its direction of motion. In order to implement the generation of swept volume, researchers have taken much effort to develop the techniques how to generate the envelope. However, their results are confined to envelope generated only in simple shape objects, such as polyhedra or quadric surfaces. This study provided the envelope generation algorithm of NURBS objects. Characteristic points were obtained by applying the geometric conditions of envelope to NURBS equations, and then characteristic curves were created by means of interpolating those points. Silhouette edges were determined in the following procedures. First, two adjacent surfaces which have the same edge were found from B-Rep data. Then, by taking the scalar product of velocity vector of a point on that edge with each normal vector on two surfaces, silhouette edges were discriminated. Finally, envelope was generated along moving direction in the form of ruled surfaces by using both the partial information between initial and final position of objects affecting envelope along with characteristic curves and silhouette edge. Since this developed algorithm can be applied not only to NURBS objects but also to their Boolean objects, it can be used effectively in various applications.

• 대한공간정보학회지
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• 제7권1호
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• pp.41-52
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• 1999

인접하는 수치지도 경계상의 불일치 문제를 해결하기 위해서 중간선 방법이 광범위하게 사용되어 왔다. 하지만, 이 방법은 인접하는 경계선 주위의 객체에 대해서 위상정보의 일관성을 상실하거나 정확도의 저하를 초래할 수 있다 본 논문에서는 이러한 중간선 방법의 문제점을 해결하기 위해서 두 가지 에지 메칭 방법을 제시한다 첫 번째 방법은 경계선 주위에 위치하고 있는 객체에 대해서 신축적으로 변환하는 러버쉬팅에 기초한 방법이다. 두 번째 방법은 경계선으로부터의 거리 함수를 이용하여 객체들의 기하적인 정보를 변환한다. 이러한 방법들은 이전의 방법에 비해서 위상정보를 유지하고 정확도를 향상시키는 장점이 있다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.781-784
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• 2002

Adhesion phenomenon is more significant for smaller objects, because adhesional force is proportional to size of the objects while gravitational force is proportional to the third power of it. For the purpose of microassembly, theoretical understanding is required for the Adhesion phenomenon. Authors have developed a force measurement system in an ultra-high vacuum chamber of Auger electron spectroscopy. The force between arbitrary combination of materials can be measured at a pressure less than 100 nPa after and before Ar ion sputtering and chemical analysis for several atomic layers of the surface. The results are successfully interpreted with a theory of contact mechanics. Since surface energy is quite important in the interpretation, electronic theory is used to evaluate the surface energy. In the manipulation of small objects, the adhesional force is always attractive. Repulsive force is essential for the manipulation. It can be generated by Coulomb interaction. The voltage required for detachment is theoretically analyzed and the effect of boundary conditions on the detachment is obtained. The possibility and limitations of micro-manipulation using both the adhesion phenomenon and Coulomb interaction are theoretically clarified. Its applicability to nano-technology is found to be expected.

• 물과 미래
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• 제20권4호
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• pp.249-256
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• 1987

유한수심의 해역중에 잠겨있는 고정된 2차원 구조물에 작용하는 파력을 경계요소법의 선형요소에 의해 해석하였다. 파력은 2차원 선형과 이론으로부터 해석하였으며, 입사파 방향은 무한히 긴 구조물의 직각방향으로 진행한다고 가정하였다. 본 연구에서는 바닥위에 놓여있는 반원 및 원형 단면 송유관, 수중에 잠겨있는 단면 송유관 그리고 임의 형상의 잠제에 작용하는 파력에 관해 해석하였다. 본 계산의 신뢰도를 검증하기 위하여 기존의 실험적, 이론적 결과 및 수치결과와 각각 비교하였다.

• 한국통신학회:학술대회논문집
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• 한국통신학회 1986년도 추계학술발표회 논문집
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• pp.45-52
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• 1986

This paper presents an experimental model-based vision system which can identify and locate object in scenes containing multiple occluded parts. The objent are assumed to be regid, planar parta. In any recognition system the type of object that might appear in the image dictates the type of knowledge that is needed to recognize the object. The data is reduced to a seguential list of points or pixel that appear on the boundary of the objects. Next the boundary of the object is smoothed using a polygonal approximation algorithm. Recognition consists in finding the prototype that matches model to image. The best match is obtained by optimising some similarity measure.

• 대한전자공학회논문지
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• 제25권7호
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• pp.807-818
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• 1988

This paper proposes new algorithms for the estimation of displacement vector and moving object extraction using difference picture. First, the relations between the boundary of moving objects in two consecutive image and the boundary of difference picture regions are analyzed, then displacement vector estimation algorithm is proposed. Using the estimated displacement vector, moving objects are directly extracted from difference picture. Since the proposed algorithms do not process gray-valued image, they have a short processing time and are suitable to real time processing. From the experimental results, we observed that, if difference picture is wel extracted, the proposecd algorithms work well even in the circumstances of complex background, fast or slow motion, rotation etc., including occlusion where is not moving area.

• 수산해양교육연구
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• 제9권1호
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• pp.40-48
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• 1997

In this study, uniform pressure distribution with small hole on the surface of symmetric object were given to reduce the viscous frictional force. The results were as follows : 1. The velocity on upper stream were accelerated by uniform pressure distribution on symmetric objects for reducing the viscous frictional resistances. 2. The effects of the distributed small holes were reduced the viscous frictional resistances in down stream region more than upper stream due to the increasing pressure in reverse flow region. 3. The viscous skin friction on surface of symmetric objects with and without distributed small holes are effect in region of upper stream and much decreased in down stream region due to increasing of boundary layer thickness.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.588-592
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• 2015

Many studies have affirmed a negative influence of fragmentation on learning and knowledge sharing in construction projects. However, the literature overlooked enablers of learning within this context. The purpose of this paper is to explore the factors that facilitate project learning and ways to negate any unbecoming effects of fragmentation. Qualitative study used to explore the enablers through interviews administered to 11 top management individuals working in different construction projects in Malaysia. The findings revealed the following factors: participation, relationships, togetherness, and roles of project leader and coordinator. The role of boundary objects was also highlighted including information technology (IT), contract and procedures, drawings, specifications, and reports. The outcome of this paper initiates the development of a model for better knowledge creation and sharing in construction projects. The significance of this model stems from its ability to connection both the characteristics of construction project and project learning theories using the enablers. It is envisaged that future work will be to confirm the model in a quantitative study.

• 대한전자공학회논문지SP
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• 제43권5호
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• pp.12-21
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• 2006

본 논문에서는 컬러 영상에서 배경의 복잡도와 객체의 위치에 관계없이 영상 내에 존재하는 중요 객체를 자동으로 추출하는 방법을 제안한다. 제안하는 방법은 중요 객체를 추출하기 위해 에지(edge) 정보와 색상(color) 정보를 이용한 특징 지도를 사용한다. 또한, 효과적인 객체 추출을 위해서 참조 지도(reference map)를 제안한다. 참조 지도를 생성하기 위해서는 영상에서 사람의 시각에 두드러지게 구분되는 영역을 표현하는 특징 지도(feature map)를 먼저 생성한다. 그런 다음, 특징 지도들을 효과적으로 결합하여 배경의 영향을 최소화 하면서, 중요 객체가 존재할 확률이 높은 영역들을 포함하는 참조 지도를 생성한다. 특징 지도를 생성하기 위해서는 밝기 차 정보를 나타내는 에지와 YCbCr 컬러와 HSV 컬러 공간에서의 색상 성분을 사용하며, 특징 지도에 대한 생성 방법은 영상 내에서 밝기차이와 색상차이에 의해서 나타나는 경계 부분을 추출하는 방법을 사용한다. 최종적으로 중요 객체가 존재하는 영역을 나타내기 위해서 참조 지도와 특징 지도들을 결합한 결합 지도(combination map)를 생성한다. 결합 지도는 중요 객체의 외곽선 정보만을 표현하기 때문에, 객체 전체를 표현할 수 있는 객체 후보 영역을 추출하는데, 이를 위해서는 객체 후보 영역을 추출하기 위해서 convex hull 알고리즘을 사용한다. Convex hull 알고리즘에 의해서 추출된 영역은 여전히 배경 부분을 포함하고 있으므로, 영상 분할 방법을 적용하여 배경을 제거한 후 영상에서의 중요 객체를 추출한다. 제안한 알고리즘의 성능을 실험적으로 확인한 결과, 평균적으로 84.3%의 정확율과 81.3%의 재현율의 성능을 보였다.