• 대한안전경영과학회:학술대회논문집
• /
• 대한안전경영과학회 2006년도 추계공동학술대회
• /
• pp.239-254
• /
• 2006

In mold structure machining, tool interference is a phenomenon which results from a collision between a blade of tool and a workpiece. Also tool collision is a phenomenon which results from a collision of holder with the object to be machined. These phenomena not only cause damages to mold and tool but also increase machining time and cost. To detect a collision of a tool to mold structure, first of all, the mold structure and a tool must be defined with famous geometric models such CSG, B-rep, and Voxel. A tool is defined as a combination of the blade, the shank, and the holder. This thesis reviews various collision detection algorithms using z-map and computer 3D graphic collision detection algorithms for the tool in machining a mold structure.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 추계학술대회논문집
• /
• pp.954-957
• /
• 2004

Based on the authors' previous work, where a geometric constraint handling technique for stiffener layout optimization problem using geometry algorithms was proposed, stiffener layout optimization to maximize natural frequencies of a curved three-dimensional shell structure was performed with a projection method. The original geometry of the shell structure was first projected on a two-dimensional plane, and then the whole optimization process was performed with the projected geometry of the shell except that the original shell structure was used for the eigenproblem solving. The projection method can be applied to baseline structures with a one-to-one correspondence between original and projected geometries such as automobile hoods and roofs.

• 한국가시화정보학회지
• /
• 제21권1호
• /
• pp.40-46
• /
• 2023

For application to drag-based propulsion system, the dynamics of a segmented structure with multiple hinges undergoing oscillatory motion are investigated. The side flaps are connected to a centre rod with elastic plates acting as hinges. The hinges bend to only one direction so that the structure behave asymmetrically between the power stroke and the recovery stroke. An analytical model is proposed, which estimates the asymmetric deformation of the segmented structure coupled with hinges. Using the proposed model, the effects of key geometric and kinematic parameters on the dynamics of the structure are analyzed.

• Wind and Structures
• /
• 제31권4호
• /
• pp.373-380
• /
• 2020

For large-scale 5MW offshore wind turbines, the discrete equation of fluid domain and the motion equation of structural domain with geometric nonlinearity were built, the three-dimensional modeling of the blade considering fluid-structure interaction (FSI) was achieved by using Unigraphics (UG) and Geometry modules, and the numerical simulation and the analysis of the vibration characteristics for wind turbine structure under rotating effect were carried out based on ANSYS software. The results indicate that the rotating effect has an apparent effect on displacement and Von Mises stress, and the response and the distribution of displacement and Von Mises stress for the blade in direction of wingspan increase nonlinearly with the equal increase of rotational speeds. Compared with the single blade model, the blade vibration period of the whole machine model is much longer. The structural coupling effect reduces the response peak value of the blade displacement and Von Mises stress, and the increase of rotational speed enhances this coupling effect. The maximum displacement difference between two models decreases first and then increases along wingspan direction, the trend is more visible with the equal increase of rotational speed, and the boundary point with zero displacement difference moves towards the blade root. Furthermore, the Von Mises stress difference increases gradually with the increase of rotational speed and decreases nonlinearly from the blade middle to both sides. The results can provide technical reference for the safe operation and optimal design of offshore wind turbines.

• 한국지능시스템학회논문지
• /
• 제11권9호
• /
• pp.782-787
• /
• 2001

본 논문에서는 F-투영과 기하학적인 성장 기준을 이용하여 모듈화된 웨이블렛 신경망(MWNN)의 적응구조를 설계하기 위한 성장과 소거 알고리즘을 제안한다. 기하학적인 성장 알고리즘은 지역 오차를 고려한 추정 에러 기준과 이미 존재하는 다른 웨이블렛 함수와 근사적인 직교성을 보장하도록 웨이블렛 함수를 배열할 수 있는 각도 기준으로 구성되어 있다. 이러한 기준은 망의 설계자가 설계자의 의도대로 MWNN을 구성할 수 있는 방법론을 제시한다. 제안한 성장 알고리즘은 모듈과 모듈의 크기를 성장시킨다. 또한 소거 알고리즘은 MWNN의 모듈에 사용되는 웨이블렛 신경망의 지역화 특성에 기인한 문제점을 극복하기 위해 구성된 MWNN에서 불필요한 모듈의 노드나 모듈을 제거한다. 제안한 MWNN의 적응 구조 설계 알고리즘을 1, 2차원 대상 함수에 적용하여 성능을 검증하였다.

• 대한조선학회논문집
• /
• 제31권1호
• /
• pp.42-49
• /
• 1994

조선 CIM 시스템은 제품 모델을 중심으로 한 정보의 통합화를 중점적으로 추구하여야 하므로, 이 제품 모델을 기능 모델과 형상 모델로 구분하였다. 조선을 위한 제품 모델의 근간이 되는 형상 모델을 오일러 조작을 기초로 하는 비다양체 모델의 자료 구조를 이용하여 각각 구획 배치, 구조 설계 및 공정 계획의 입장에서 이용하는 방법에 대하여 연구하였다.

• 한국ITS학회 논문지
• /
• 제20권1호
• /
• pp.193-202
• /
• 2021

고정밀 지도의 갱신은 정사영상 또는 점군 데이터 등을 원천 자료로 하여 기하 정보를 우선적으로 수정한 이후 지도를 구성하는 공간객체들 간의 연관관계를 재정립하는 방식으로 진행된다. 이러한 일련의 과정들은 기하 정보를 처리하는 데에 많은 시간을 소요하므로 차량의 실시간 경로 계획(Real-time route planning)에 빠르게 적용되기 어렵다. 따라서 이 연구에서는 그래프 구조를 활용하여 경로 계획을 위한 도로 연결구조를 우선적으로 업데이트 하는 방식 및 도로 네트워크의 특징을 고려한 그래프 구조의 저장 유형을 제안하였다. 또한 제안된 방법을 실제 도로 자료에 적용해 봄으로써 실시간 경로 정보 전송 시의 활용 가능성에 대해 검토하였다.

• 한국정보과학회:학술대회논문집
• /
• 한국정보과학회 2005년도 가을 학술발표논문집 Vol.32 No.2 (1)
• /
• pp.958-960
• /
• 2005

We consider a point robot in the plane whose turning radius is constrained to be at least 1 and that is not allowed to make reversals. Given a starting configuration(a location and an orientation) for the robot, we give a new geometric proof on the combinatorial structure of curvature-constrained shortest paths to a final point with free orientation.

• 한국공간구조학회논문집
• /
• 제16권3호
• /
• pp.67-78
• /
• 2016

Determining of the shape in the process of design for natural draught cooling tower is very important, because the shape of hyperbolic shell is respond sensitively to dynamic behavior of the whole cooling tower against wind load. In engineering practice, the geometric parameters have been determining based on the natural frequency. This study analyses influence of the tower shell geometric parameters on the structural behavior. For three representative models were selected, they were analyzed based on evaluation of damage by means of nonlinear FE-method. As a result, a hyperbolic rotational shell with the small radius overall was the lowest damage index induced by sufficient capacity of the stress redistribution and thus a wind-insensitive structure.

• Bulletin of the Korean Chemical Society
• /
• 제28권10호
• /
• pp.1705-1708
• /
• 2007

Geometric manipulation of molecules is an essential elementary component in computational modeling programs for molecular structure, stability, dynamics, and design. The computational complexity of transformation of internal coordinates to Cartesian coordinates was discussed before.1 The use of rotation matrices was found to be slightly more efficient than that of quaternion although quaternion operators have been widely advertised for rotational operations, especially in molecular dynamics simulations of liquids where the orientation is a dynamical variable.2 The discussion on computational efficiency is extended here to a more general case in which bond angles and sidechain torsion angles are allowed to vary. The algorithm of Thompson3 is derived again in terms of quaternions as well as rotation matrices, and an algorithm with optimal efficiency is described. The algorithm based on rotation matrices is again found to be slightly more efficient than that based on quaternions.