• 한국생산제조학회지
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• 제5권2호
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• pp.20-28
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• 1996

Compound surface modeling is widely used for die cavities and punches. A compound surface is defined in 3-D space by specifying the topological relationship of several anlytic surface elements and a sculptured surface. A constructive solid gemonetry scheme is employed to model the analytic compound surface. the desired compound surface can be accomplished by specifying topological reationship in terms of boolean relations between pimitives and the sculptured surfaces. Additionally, a method is presented for checking and avoiding the tool interference occuued in machining the compound surface. Using this method. the interference of concave, convex, and side region can be checked easily and avoided rpapidly.

• 한국정밀공학회지
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• 제25권3호
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• pp.147-156
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• 2008

A new approach based on cone prism intersection method combined with sorting algorithm is proposed for the fast and robust signed distance field computation. In the method, the space bounding the geometric model composed of triangular net is divided into multiple smaller cells. For the efficient calculation of distance fields, valid points among the triangular net which will generate minimum distances with current cell are selected by checking the intersection between current cell and cone prism generated at each point. The method is simple to implement and able to achieve an order of magnitude improvement in the computation time as compared to earlier approaches. Further the method is robust in handling the traditional sign problems. The validity of the suggested method was demonstrated by providing numerous examples including Boolean operation, shape deformation and morphing of complex geometric models.

• 한국CDE학회논문집
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• 제4권1호
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• pp.43-51
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• 1999

Producing the relevant information (features) from the CAD models of CAM, called feature recognition or extraction, is the essential stage for the integration of CAD and CAM. Most feature recognition methods, however, have problems in the recognition of intersecting features because they do not handle the intersection geometry properly. In this paper, we propose a machining feature recognition algorithm, which has a solid model consisting of orthogonal primitives as input. The algorithm calculates candidate features and constitutes the Intersection Geometry Matrix which is necessary to represent the spatial relation of candidate features. Finally, it recognizes machining features from the proposed candidate features dividing and growing systems using half space and Boolean operation. The algorithm has the following characteristics: Though the geometry of part is complex due to the intersections of design primitives, it can recognize the necessary machining features. In addition, it creates the Maximal Feature Volumes independent of the machining sequences at the feature recognition stage so that it can easily accommodate the change of decision criteria of machining orders.

• 정보관리연구
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• 제24권3호
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• pp.73-100
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• 1993

본 연구(硏究)는 불 정보 시스템의 단점을 보완하는 방법으로 퍼지 논리(論理)를 이용한 정보검색시스템을 설계하였다. 퍼지 정보검색 시스템은 질의어(質疑語)와 문헌들을 표현하는 각 용어(用語)들에 가중치(加重値)를 부여하고, 이것을 바탕으로 질의어에 대한 각 문헌들의 적합도(適合度)를 결정하는 것이다. 본 연구에서는 기존의 연구들을 비교 분석한 후, 효과적인 모델을 제시하고 시스템 성능을 평가하였다.

• 한국CDE학회논문집
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• 제11권4호
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• pp.235-245
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• 2006

This paper proposes a CSG-based representation scheme for heterogeneous objects including multi-material objects and Functionally Graded Materials (FGMs). In particular, this scheme focuses on the construction of complicated heterogeneous objects guaranteeing desired material continuities at all the interfaces. In order to create various types of heterogeneous primitives, we first describe methods for specifying material composition functions such as geometry-independent, geometry-dependent functions. Constructive Material Composition (CMC) and corresponding heterogeneous Boolean Operators (e.g. material union, difference, intersection. and partition) are then proposed to illustrate how material continuities are dealt with. Finally, we describe the model hierarchy and data structure for computer representation. Even though the proposed scheme alone is sufficient for modeling all sorts of heterogeneous objects, the proposed scheme adopts a hybrid representation between CSG and decomposition. That is because hybrid representation can avoid the unnecessary growth of binary trees.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2014년도 추계학술발표대회
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• pp.849-852
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• 2014

Reverse engineering of gene regulatory network is a challenging task in computational biology. To detect a regulatory relationship among genes from time series data is called reverse engineering. Reverse engineering helps to discover the architecture of the underlying gene regulatory network. Besides, it insights into the disease process, biological process and drug discovery. There are many statistical approaches available for reverse engineering of gene regulatory network. In our paper, we propose pairwise mutual information for the reverse engineering of a gene regulatory network from time series data. Firstly, we create random boolean networks by the well-known $Erd{\ddot{o}}s-R{\acute{e}}nyi$ model. Secondly, we generate artificial time series data from that network. Then, we calculate pairwise mutual information for predicting the network. We implement of our system on java platform. To visualize the random boolean network graphically we use cytoscape plugins 2.8.0.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.547-552
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• 2003

In mold machining, there are many concave machining regions where chatter and tool deflection occur since MRR (material removal rate) increases as curvature increases even though cutting speed and depth of cut are constant. Boolean operation between stock and tool model is widely used to compute MRR in NC milling simulation. In finish cutting, the side step is reduced to about 0.3mm and tool path length is sometimes over 300m. so Boolean operation takes long computation time and includes much error if the resolution of stock and tool model is larger than the side step. In this paper, curvature of CL(cutter location) surface and side step of tool path is used to compute the feedrate for constant MRR machining. The data structure of CL surface is Z-map generated from NC tool path. The algorithm to get local curvature from discrete data was developed and applied to compute local curvature of CL surface. The side step of tool path was computed by point density map which includes cutter location point density at each grid element. The feedrate computed from curvature and side step is inserted to new tool path to regulate MRR. The resultants wire applied to feedrate optimization system which generates new tool path with feedrate from NC codes for finish cutting. The system was applied to speaker mold machining. The finishing time was reduced to 12.6%. tool wear was reduced from 2mm to 1.1mm and chatter marks and over cut on corner were removed.

• 한국CDE학회논문집
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• 제5권3호
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• pp.242-254
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• 2000

This paper describes an efficient solid modeling method for thin-walled plastic or sheet metal parts, based on the non-manifold offsetting operations. Since the previous methods for modeling and converting a sheet into a solid have adopted the boundary representations for solid object as their topological framework, it is difficult to represent the exact adjacency relationship between topological entities of a sheet model and a mixture of wireframe and sheet models that can appear in the meantime of modeling procedure, and it is hard to implement topological operations for sheet modeling and transformation of a sheet into a solid. To solve these problems, we introduce a non-manifold B-rep and propose a sheet conversion method based on a non-manifold offset algorithm. Because the non-manifold offset aigorithm based on mathematical definitions results in an offset solid with tubular and spherical thickness-faces we modify it to generate the ruled or planar thickness-faces that are mostly shown in actual plastic or sheet metal parts. In addition, in order to accelerate the Boolean operations used the offset algorithm, we also develope an efficient face-face intersection algorithm using topological adjacency information.

• 한국정밀공학회지
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• 제13권3호
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• pp.158-164
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• 1996

In this paper, the CNC cutting planning module for product with three dimensional solid shape is realized to develop a smart CAD/CAM system which performs systematically from the shape design of procuct by the B-Rep solid modeler to the CNC cutting of product by a machining center. The three dimensional solid shape of product can be easily designed and constructed by the Euler operators and Boolean operators of the solid modeler. And the various functions such as the automatic generation of tool path for the rough and finish cutting processes, the automatic elimination of overcut, the automatic generation of CNC code for the machining center and do on, are established. Especially, the overcut-free tool paths are obtained by splitting the CL solid which is composed of the offset surfaces of the solid shape of product.

• 한국정보처리학회논문지
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• 제3권6호
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• pp.1397-1406
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• 1996

본 논문에서는 자동화된 생산 시스템과 조립 시스템에서 반제품을 생산기기들 사 이로 운반하기 위해 가장 많이 이용되고 있는 컨베이어 (conveyor) 시스템의 이산구 조 모델을 제안한다. 조립라인과 같이 조립 기기들 사이에 반제품을 운반하는 데 걸 리는 시간이 단위공정을 수행하는 데 걸리는 시간보다 클 경우, 조립기기들의 배치와 컨베이어로 연결되는 조립기기들 사이의 거리는 전체 조립시스템의 성능에 중요한 영 향을 미치게 되므로 컨베이어 시스템의 특성을 정량적으로 분석하기 위한 모델이 필 요하다. 본 논문에서 제안하는 모델은 팔레트(pallet)를 이용하는 컨베이어 시스템에 서 각각의 컨베이어의 길이가 팔레트 길이의 정수 배이며 컨베이어의 속도가 일정하 다는 가정을 전제로 한다. 이런 가정 하에서 컨베이어 운동의 관측 시간과 컨베이어 의 길이는 양자화 될 수 있으므로 각 샘플링 시각에서의 컨베이어 시스템의 상태는 양자화된 컨베이어상의 팔레트 유무와 이 팔레트의 이동도(mobility)를 나타내는 두 가지의 Boolean 변수로 간단히 표시될 수 있다. 이 두 변수를 바탕으로 전체 컨베이 어 시스템은 생산기기들 사이의 통로인 branch와 branch의 끝점인 knot의 조합으로 구성된 network으로 모델링된다. 이 모델링 방법으로 여러 가지 모양의 컨베이어 시 스템을 모델링해 본 결과 복잡한 토폴로지의 컨베이어 시스템도 간단히 모델링 및 시 뮬레이션될 수 있었으며 공장설계, 공정제어 등의 시뮬레이션에 유용하게 이용될 수 있음을 보여 주었다.