• 산업경영시스템학회지
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• 제32권1호
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• pp.102-110
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• 2009

Concurrent Engineering(CE) has presented new possibilities for successful product development by incorporating various product life-cycle functions from the earlier stage of design. In the product design, geometric representation is vital not only in its traditional role as a means of communicating design information but also in its role as a means of externalizing designer's thought process by visualizing the design product. During the last dozens of years, there has been extraordinary development of computer-aided tools intended to generate, present or communicate 3D models. However, there has not been comparable progress in the development of 3D-CAD systems intended to represent and manipulate a variety of product life-cycle information in a consistent manner. This paper proposes a novel concept, Minus Volume (MV), to incorporate various design information relevant to product lift-cycle functions. MV is a functional shape that is extracted from a design object within a bounding box. A prototype 3D-CAD system is implemented based on the MV concept and illustrated with the successful implementation of concurrent design and manufacturing.

• 한국전자거래학회:학술대회논문집
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• 한국전자거래학회 2001년도 International Conference CALS/EC KOREA
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• pp.615-624
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• 2001

Internet technology opens up another domain for building future CAD/CAM environment. The environment will be global, network-centric, and spatially distributed. In this paper, we present a new approach to network-centric virtual prototyping (NetVP) in a distributed design environment. The presented approach combines the current virtual assembly modeling and analysis technique with distributed computing and communication technology fur supporting virtual prototyping activities over the network. This paper focuses on interoperability, shape representation, and geometric processing for distributed virtual prototyping. STEP standard and CORBA-based interfaces allow the bi-directional communication between the CAD model and virtual prototyping model, which makes it possible to solve the problems of interoperability, heterogeneity of platforms, and data sharing. STEP AP203 and AP214 are utilized as a means of transferring and sharing product models. In addition, Attributed Abstracted B-rep (AAB) is introduced as 3D shape abstraction for transparent and efficient transmission of 3D models and for the maintenance of naming consistency between CAD models and virtual prototyping models over the network.

• 한국전자파학회논문지
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• 제30권6호
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• pp.487-497
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• 2019

탄도미사일은 작은 레이다 단면적 및 빠른 기동 특성으로 인하여 탐지가 매우 힘들며, 또한 탄도미사일의 각 비행단계에서 탄두와 유사한 운동 변수로 기동하는 연료탱크 및 기만체의 존재로 인하여 탄두의 식별 및 요격이 매우 어렵다. 따라서 비행 단계에 따라 표적의 기동 및 미세운동을 이용한 특성벡터가 필요하며, 또한 이를 적절히 융합하여 비행단계에 상관없이 식별하는 방법이 요구된다. 본 연구에서는 탄도미사일의 비행단계에 따른 유용한 특성벡터를 소개하고, 이를 특성벡터 및 구분기 레벨에서 융합하는 효과적인 기법을 제안한다. CAD 모델들을 사용하여 예측된 레이다 신호들로 시뮬레이션을 수행한 결과, 구분기 레벨 융합을 통하여 잡음환경 내에서 비행단계에 상관없이 종말 단계로 갈수록 보다 향상된 탄두 식별이 가능하였다.

• Journal of Computational Design and Engineering
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• 제3권2호
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• pp.161-177
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• 2016

In history based parametric CAD modeling systems, persistent identification of the topological entities after design modification is mandatory to keep the design intent by recording model creation history and modification history. Persistent identification of geometric and topological entities is necessary in the product design phase as well as in the re-evaluation stage. For the identification, entities should be named first according to the methodology which will be applicable for all the entities unconditionally. After successive feature operations on a part body, topology based persistent identification mechanism generates ambiguity problem that usually stems from topology splitting and topology merging. Solving the ambiguity problem needs a complex method which is a combination of topology and geometry. Topology is used to assign the basic name to the entities. And geometry is used for the ambiguity solving between the entities. In the macro parametrics approach of iCAD lab of KAIST a topology based persistent identification mechanism is applied which will solve the ambiguity problem arising from topology splitting and also in case of topology merging. Here, a method is proposed where no geometry comparison is necessary for topology merging. The present research is focused on the enhancement of the persistent identification schema for the support of ambiguity problem especially of topology splitting problem and topology merging problem. It also focused on basic naming of pattern features.

• 한국통신학회논문지
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• 제36권2C호
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• pp.65-77
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• 2011

최근 CAD 설계도면 및 GIS 디지털 맵과 같은 벡터 데이터 모델의 응용 분야가 확대되면서 이에 대한 보호기술이 필요하게 되었다. 본 논문에서는 벡터 데이터 모델의 인증 또는 복사방지에 펄요한 벡터 데이터 해싱 방법을 제안한다. 제안한 해싱에서는 벡터 데이터 모델 내 주요 레이어 상에 폴리라인들을 그룹화한 다음, 폴리라인의 1차 및 2차 곡선 곡률 분포에 따라 그룹 계수를 생성한다. 그리고 이들 그룹 계수를 랜덤 계수 키 패턴으로 투영기에 의하여 특징 계수를 얻은 다음, 이를 이진화 과정에 의하여 최종 이진 해쉬를 생성한다. 설계도면 및 디지털 맵을 이용한 실험 결과로부터 제안한 방법에 의하여 생성된 해쉬가 다양한 공격에 대한 강인성과 랜텀 키에 의한 보안성 및 유일성을 만족함을 확인하였다.

• 한국정밀공학회지
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• 제13권9호
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• pp.84-93
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• 1996

This paper describes the development of new feature positioning method which embedded into the top-down assembly modeling system supporting conceptual design. In this work, the user provides the geometric constraints representing the position and size of features, then the system calculates their proper solution. The use of geometric constraints which are easy to understand intuitively enables the user to represent his design intents about geometric shapes, and enables the system to propagate the changes automatically when some editing occurs. To find the proper solution of given constraints, the Selective Solving Method in which the redundant or conflict equations are detected and discarded is devised. The validity of feature shapes satisfying the constraints can be maintained by this technique, and under or over constrained user-defined constraints can also be estimated. The problems such as getting the initial guess, controlling the multiple solutions, and dealing with objects of rotational symmetry are also resolved. Through this work, the feature based modeling system can support more general and convenient modeling method, and keeps the model being valid during modifying models.

• 한국공작기계학회논문집
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• 제17권4호
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• pp.140-145
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• 2008

Recently more complex geometric shapes, including freeform surfaces, are adopted for the design of products to emphasize style or beauty. Modeling of these products is extremely difficult or often impossible. Reverse engineering is the latest technology that can solve the problem by generating CAD models from the physical mockups or prototype models. Reverse engineering uses the coordinate measuring machine(CMM) to get the shape data of products. CMM is limited by the size of the product; therefore it must need the feature to solve it. The tooling-ball which is generally used for feature has difficulty in being used for soft products. Besides, the higher the accuracy of the tooling-ball is, the more expensive its cost is. This study will develop the feature of high accuracy without additional tools and compare the difference of accuracy by it.

• 대한공간정보학회지
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• 제17권3호
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• pp.13-21
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• 2009

수치지형도는 정확성과 함께 최신성을 가져야만 국가공간정보로서 그 역할을 다할 수 있으나 항공사진 촬영과 측량, 현지조사를 수행해야 하는 제작과정의 특성상 많은 시간과 비용이 소요되어 최신성을 유지하는데 한계가 있다. 준공도면을 활용하여 수시 갱신한다면 기 작성된 도면을 재활용하므로 불필요한 국가예산의 낭비를 막을 수 있고 측량된 성과를 이용할 수 있으므로 정확한 갱신이 가능하여 그 효과가 크나 CAD 도면 표준화 미비, 준공도면과 수치지형도 파일 형식의 상이, 대장자료의 미비, 입력 객체와 기존 객체와 위상 관계 등으로 인해 어려움이 있는 실정이다. 본 연구에서는 첫째, 준공도면에서 추출된 CAD 객체를 기존 객체의 존재 여부에 따라 신규 혹은 갱신으로 안착시키고 객체간 공간관계에 따라 위상정보를 생성한 후 둘째, 이의 무결성 여부를 검수하여 효율적으로 수치지형도의 갱신을 수행할 수 있는 방안을 제시하였고 그 결과로 수치지형도의 정확성과 최신성을 확보하였다.

• 한국정밀공학회지
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• 제17권2호
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• pp.73-79
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• 2000

The part-surface of mold or stamping-dies consists of a compound surface which consists of lots of composite surfaces, and may have various types of feature shapes including convex sharp edge (CSE). Those CSE features should be considered with care in machining the surface, which necessitates extraction of CSE curves on a compound surface. This work can be done rather easily for a solid model which has a complete topology information. In case of the compound surface without topology information, however, such CSE curves must be gathered through some geometrical calculations paying much computation time. In the paper, extracting CSE curves by the construction of a CSE region-map which can reduce time, and detecting various common edge types are presented.

• Advances in Computational Design
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• 제5권4호
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• pp.381-396
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• 2020

This study aimed to develop an optimal model of transportation for people with disabilities. To achieve this goal, powers of research and design should be involved, including CAD software. This paper investigates both: the concept of optimal model of transportation for people with disabilities (functional, ergonomic, constructive, technological and aesthetic solutions included); and its implementation as a fully-fledged 3D-model designed in SolidWorks environment. The optimal model of transportation is complex and consists of two objects. The first object is for indoors that is a wheelchair, the second one is for street driving that is an individual vehicle. The optimal model of transportation is universal and multifunctional, which have become possible with parametric feature-based approach utilized in SolidWorks.