• 한국정밀공학회지
• /
• 제27권8호
• /
• pp.91-97
• /
• 2010

Micro-abrasive Jet Machining is one of the new technology which enables micro-scale machining on the surface of high brittle materials. In this technology it is very important to fabricate a mask that prevents excessive abrasives not to machine un-intend surface. Our previous work introduced the micro-stereolithography technology for the mask fabrication. And is good to not only planar material but also for non-planar materials. But the technology requires a 3 dimensional mask CAD model which is perfectly matched with the surface topology of parent material as an input. Therefore there is strong need to develop an automated modeling technology which produce adequate 3D mask CAD model in fast and simple way. This paper introduces a fast and simple mask modeling algorithm which represents geometry of models in voxel. Input of the modeling system is 2D pattern image, 3D CAD model of parent material and machining parameters for Micro-abrasive Jet Machining. And the output is CAD model of 3D mask which reflects machining parameters and geometry of the parent material. Finally the suggested algorithm is implemented as software and verified by some test cases.

• 한국산학기술학회논문지
• /
• 제18권9호
• /
• pp.1-8
• /
• 2017

본 연구의 목적은 물리적 메모리 할당이 어려운 대용량 BIM(Building Information Modeling) 형상 데이터를 처리하기 위한 캐쉬(cache) 구조를 제안한다. 조달청 등 공공기관에서 BIM 발주가 많아짐에 따라 대용량 BIM 형상 데이터를 가시화하고, 계산해야 하는 경우가 많아지고 있다. 규모가 크고 복합적인 시설물의 경우, 렌더링 및 계산해야하는 형상 수가 많아 사용자가 BIM 모델을 검토하고, 단면을 확인하는 데 어려움을 겪는 경우가 있다. 예를 들어, 설계, 검토 협업 시, 대용량 BIM 데이터를 네트워크를 통해 전달받아야 할 경우, 다운로드에 많은 시간이 걸릴 수 있고, 물리적 여유 메모리 한계를 넘어가면, 에러로 가시화나 형상정보 추출이 불가능할 수도 있다. 물리적 메모리가 부족하거나 대역폭이 적은 네트워크 상에서 대용량 BIM 데이터를 활용하기 위해서는, BIM 형상 렌더링 및 계산 시점에 필요한 데이터만 메모리로 캐쉬(cache) 처리하는 것이 유리하다. 이 연구는 물리적 메모리 할당이 어려운 대용량 BIM 형상 데이터를 효과적으로 렌더링하고 계산하기 위한 BIM 형상 캐쉬 구조를 제안한다.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 1997년도 특별강연 및 춘계학술발표 개요집
• /
• pp.176-179
• /
• 1997

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2003년도 추계학술발표대회 개요집
• /
• pp.224-226
• /
• 2003

• Bulletin of the Korean Chemical Society
• /
• 제14권1호
• /
• pp.18-20
• /
• 1993

• 한국전산구조공학회논문집
• /
• 제15권1호
• /
• pp.33-42
• /
• 2002

본 연구에서는 3차원 곡면의 매개변수식 기하 표현법과 계층적/관계형 자료 구조를 이용하여 3차원 터널을 자동으로 모델링할 수 있는 방안을 제시한다. 매개변수식 기하 표현법과 계층적/관계형 자료 구조의 이용은 3차원 터널 표현의 일반화와 확장성을 제공하며 해석을 위한 터널 구조의 특성을 정확하게 처리할 수 있게 한다. 그리고 터널 곡면의 곡률 특징을 이용하여 2차원 요소망 생성 알고리즘을 사용하여 3차원 요소망을 자동으로 생성할 수 있다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
• /
• pp.142-147
• /
• 2004

The flow in the LOX manifold of liquid rocket has been investigated using a CAE technique with an objective of economical modeling of injection holes in order to reduce the overall computational cost of flow analysis during the optimal rocket design procedure. The computational geometry is very close to that of the actual rocket design and the flow condition through the injection holes resembles that in the actual manifold of the liquid rocket. The result shows that the flow in the plane just above the injection holes is not uniformly distributed in terms of pressure and mass flow rate and this is attributed to the large-scale flow patterns present the LOX manifold. Thus, the flow physics should be understood correctly before making any attempt to model the injection holes. In the present study, several boundary conditions which were designed to effectively replace the presence of injection holes have been tested and it was found that a simple modeling can be possible by mimicking the actual geometry of the injection holes. By using this simple injection hole modeling, it was able to obtain about 30% reduction in computational cost but it was still able to reproduce the flow patterns correctly. Also the flow has been analyzed after incorporating a couple of different types of pre-distributors in LOX manifold and the effect of those will be discussed.

• 한국수학교육학회지시리즈D:수학교육연구
• /
• 제26권3호
• /
• pp.203-233
• /
• 2023

Recent international reform movements call for attention on modeling in mathematics classrooms. However, definitions and enactment principles are unclear in policy documents. In this case study, we investigated United States high-school mathematics teachers' experiences in a professional development program focused on modeling and its enactment in schools. Our findings share teachers' experiences around their discovery of different conceptualizations, appreciations, and conflicts as they envisioned incorporating modeling into classrooms. These experiences show how professional development can be designed to engage teachers with forms of modeling, and that those experiences can inspire them to consider modeling as an imperative feature of a mathematics program.

• 한국정밀공학회지
• /
• 제26권12호
• /
• pp.138-145
• /
• 2009

Custom medical treatment is being widely adapted to lots of medical applications. A technology for 3D modeling is strongly required to fabricate medical implants for individual patient. Needs on true 3D CAD data of a patient is strongly required for tissue engineering and human body simulations. Medical imaging devices show human inner section and 3D volume rendering images of human organs. CT or MRI is one of the popular imaging devices for that use. However, those image data is not sufficient to use for medical fabrication or simulation. This paper mainly deals how to generate 3D geometry data from those medical images. A new image processing technology is introduced to reconstruct 3D geometry of a human body vacancy from the medical images. Then a surface geometry data is reconstructed by using Marching cube algorithm. Resulting CAD data is a custom 3D geometry data of human vacancy. This paper introduces a novel 3D reconstruction process and shows some typical examples with implemented software.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1995년도 추계학술대회 논문집
• /
• pp.702-706
• /
• 1995

Integration of CAM and CAM information is important in the CIM era. For a CIM system, the feature representation can be a solution to the integration of product model data. These are geometry feature, functional feature, and manufacturing feature in the feature context. This paper proposes a framework to integrate the configuration design method, parametric modeling and the feature modeling method. The concept of design unit which is one level higher than functional feature and parametric modeling concept with functional features have been proposed.