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

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.1053-1056
• /
• 2008

An application of CSG (Constructive Solid Geometry) modeling technique in Machining Simulation is introduced in this paper. The current CSG model is based on z-buffer CSG Rendering Algorithm. In order to build a CSG model, frame buffers of VGA (Video Graphic Accelerator) should be used in term of color buffer, depth buffer, and stencil buffer. In addition to using CSG model in machine simulation Stock and Cutter Swept Surface (CSS) should be solid. Method to create a solid Cuboid stock and Ball-end mill CSS are included in the present paper. Boolean operations are used to produce the after-cut part, especially the Difference operation between Stock and CSS as the cutter remove materials form stock. Finally, a small program called MaSim which simulates one simple cut using this method was created.

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

• 정보교육학회논문지
• /
• 제13권3호
• /
• pp.341-349
• /
• 2009

본 논문에서는 정보 과학교육에서 디지털 시스템의 동작 원리를 이해하는데 기초가 되는 디지털 논리 회로에 대한 내용을 쉽게 이해할 수 있도록, 전기회로 실험 조작 활동을 통한 논리회로 결과 검증 방법을 제안하였다. 그리고 제안한 검증방법을 활용하고 실생활 디지털 기기 예제를 통해 PBL 기법에 기반한 논리회로의 개념교육 방법 및 부울 논리 교육 방법을 제안하고 실제 수업에 적용한 결과를 난이도 할당의 적절성 및 학생들의 문제해결력 측면에서 분석하였다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1994년도 추계학술대회 논문집
• /
• pp.689-694
• /
• 1994

In this paper, to develop a smart CAD/CAM system for systematically performing from the 3-D solid shape design of products to the CNC cutting operation of products by a machining center, a B-Rep solid modeler is realized based on the half edge data structure. Because the B-Rep solid modeler has the various capabilities related to the solid definition functions such as the creation operation of primitives and the translational and rotational sweep operation, the solid manipulation functions such as the split operation and the Boolean set operation, and the solid inversion function for effectively using the data structure, the 3-D solid shape of products can be easily designed and constructed. Also, besides the automatic generation of CNC code, the B-Rep solid modeler can be used as a powerful tool for realizing the automatic generation of finite elements, the interference check between solids, the structural design of machine tools and robots and so on.

• 한국문헌정보학회지
• /
• 제29권
• /
• pp.141-172
• /
• 1995

The main objective of this study is to analyse the information flows and representations which is shown at the displays of the user-OPACs interfaces in the 5 academic library automation systems. The findings made in the study are summarized as follows: 1) The interactive styles of that displays are based on the menu selection style. 2) The structures of information flow on that displays are the compound structure which is basically made of the network, the binary, and the pop-up structures. 3) The elements of the displays are consisted with the fields concerning the database name, the current working area, the indicator, the menu, the exit, the prompt and the system message. 4) The essential entries of the main menus are Book, Periodical. and Thesis. 5) The important languages of the command language styles are Search, Display, Print, Help, and End. 6) The elements of the display structures for the retrieval are the retrieving key, the Boolean operators, and the exit. 7) The major retrieving keys are Title, Author, Subject name, Call Number, and Publisher. 8) The marks of Boolean operators on the retrieval displays is different among the systems each other.

• 한국컴퓨터정보학회논문지
• /
• 제11권1호
• /
• pp.11-18
• /
• 2006

LAD(Logical Analysis of Data)는 Boolean-logic에 기반을 둔 데이터 마이닝 방법론이다. LAD에 의한 데이터 분석 시 중요한 과정은 데이터 집합에 숨겨진 구조적 정보를 패턴의 형식으로 발견해내는 패턴 생성 단계이다. 기존의 패턴 생성 방법은 열거법에 기반을 두고 있어 높은 차수의 패턴을 생성하는 것은 실질적으로 불가능하였다. 본 논문에서는 최적화에 기반을 둔 패턴 생성 방법론을 제안하고 혼합 정수 선형 모형과 SCP(Set Covering Problem)의 두 가지 모형을 제안한다. 기계학습 분야에서 널리 쓰이는 데이터 집합에 대해 제안된 패턴 생성 방법을 이용한 분석 실험을 통하여 기존의 패턴 생성 방법으로는 생성될 수 없는 패턴을 쉽게 생성하는 효율성을 입증하였다.

• 정보관리학회지
• /
• 제13권1호
• /
• pp.173-185
• /
• 1996

본 논문에서는 부울검색시스템에서 사용자로부터 입력되는 부울 질의를 효율적으로 연산하기 위한 부울 질의 최적화 방법 4가지를 기술한다. 첫째, 프로그래밍 언어에서 논리식의 계산에 사용되는 단거리계산 방법을 적용한다. 둘째, AND, NOT과 같은 특정 연산자를 효율적으로 연산하기 위하여 색인어 출현 빈도의 차이를 이용한다. 세째, 분배법칙이 적용된 질의를 원래의 식으로 변환하여 연산의 수를 감소시킨다. 마지막으로 반복되는 식을 포함하는 질의에 대하여 중복 연산을 회피한다. 또한 위의 4가지 방법들을 UNIX환경에서 개발된 KRISTAL-II 시스템에 구현하여, 제시된 방법들이 특정 경우에 검색 속도를 향상시킬 수 있음을 검증하였다.

• 한국CDE학회논문집
• /
• 제10권6호
• /
• pp.432-443
• /
• 2005

Recent three-dimensional feature-based CAD systems based on solid or non-manifold modelling functionality have been widely used for product design in manufacturing companies. When product models associated with features are used in various downstream applications such as analysis, however, simplified and abstracted models at various levels of detail (LODs) are frequently more desirable and useful than the full detailed model. To provide multi-resolution models, the features need to be rearranged according to a criterion that measures the significance of the feature. However, if the features are rearranged, the resulting shape is possibly different from the original because union and subtraction Boolean operations are not commutative. To solve this problem, in this paper, the new concept of the effective zone of a feature is defined and identified using Boolean algebra. By introducing the effective zone, an arbitrary rearrangement of features becomes possible and arbitrary LOD criteria may be selected to suit various applications. Besides, because the effective zone of a feature is independent of the data structure of the model, the multi-resolution modelling algorithm based on the effective zone can be implemented on any 3D CAD system based on conventional solid representations as well as non-manifold topological (NMT) representations.

• 한국비블리아학회지
• /
• 제23권2호
• /
• pp.209-233
• /
• 2012

이 연구에서는 웹기반 온라인목록 이용자들의 전반적인 검색행태를 알아보기 위해, 7년 동안의 트랜잭션 로그를 분석하였다. 웹기반 온라인목록의 검색형태는 검색전략과 검색실패의 관점에서 조사하였다. 검색전략에서는 검색유형, 접근점, 연산자, 검색문의 길이, 단어 사용횟수, 웹기반 온라인목록 이용횟수, 시간대별 및 요일별 이용횟수를 분석하였다. 또한 검색실패는 검색실패율과 접근점별 검색실패율, 연산자별 검색실패율을 분석하였다. 이 연구결과는 향후 웹기반 온라인목록 시스템과 서비스 개선에 활용될 수 있을 것으로 기대된다.