• 한국전산유체공학회지
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• 제20권2호
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• pp.37-45
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• 2015

A parametric study on the shapes of bobsleigh bumpers has been performed to reduce the aerodynamic drag. Effects of geometric parameters, such as leading angle of leading bumper, the ratio of minimum width to maximum width of leading bumper, the ratio of leading bumper length to trailing bumper length, trailing angle of trailing bumper, and the ratio of bumper height to installation location of bumper from the bottom of bobsleigh, on the aerodynamic performance of the bobsleigh were estimated using 3-D Reynolds-averaged Navier-Stokes equations. The turbulence was analyzed using the shear stress turbulence model. Reynolds number based on the hydraulic diameter of the external flow channel was in the range of 150,000~1,000,000. Numerical results for drag coefficient were validated compared to experimental data. Ranges of the five geometric parameters were determined according to the rule of Federation Internationale de Bobsleigh et de Tobaganning. The aerodynamic performance of the bobsleigh sled was most sensitive to the leading angle of leading bumper and the ratio of minimum width to maximum width of leading bumper.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제2권12호
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• pp.899-902
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• 2013

본 논문에서는 두 개의 단백질 분자가 결합하여 복합체를 구성할 때, 두 분자 간의 접촉 영역을 발견하여 3차원 공간에서 가시화하는 방법을 제시한다. 두 분자 간의 접촉 영역은 기하학적인 측면에서 서로 상보성을 보이며, 상보적인 결합의 크기를 나타내기 위한 방법으로 접촉 영역의 면적을 계산하는 방법이 주로 사용되어 왔다. 접촉 영역의 면적을 수치화한 결과와 접촉 영역의 단순 표시는 서로 다른 접촉 영역에 대해 상대적인 결합 강도를 비교하기에는 적합하지만, 접촉 영역이 가진 기하학적인 특성을 분석하기에는 부적합하다. 본 논문에서는 접촉 영역에서 상보성을 표시하기 위해 상대 분자와의 거리 정보를 가시화하는 방법을 제시한다.

• 한국CDE학회논문집
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• 제16권4호
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• pp.305-313
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• 2011

This paper proposes a method for reusing kinematic design data for virtual facilities, Making a virtual model of a facility involves two major activities: geometric design (virtual model visualization) and kinematic design that should be remodeled frequently whenever design changes occur, Conventionally, a virtual model of an automated facility focuses on the design level, which mainly deals with design verification, alternative comparison, and geometric model diagnosis, Although a design level model can be designed with the information of past models from PLM system, a simulation level model is not sufficient utilized to be reused for kinematic design purpose, We propose a method for reusing kinematic information of a past simulation model to cope with this problem, We use the concept or the 'center of mass', which is a point representing the mean position of the matter in a body or system. And we also use comparison method of a boundary box to identity which 3D objects have to be involved from the design model to a link structure that is contained in the simulation model. Because a proposed method only use not a historical approach but a geometrical approach, it is more effective to apply to the field.

• 대한산업공학회지
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• 제21권3호
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• pp.329-343
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• 1995

Traditionally, machining process sequence was influenced and constrained by the design information obtained from CAD data base, i.e., class of operations, geometric shape, tooling, geometric tolerance, etc. However, even though all the constraints from design information are considered, there may exist more than one way to feasibly machine parts. This research is focused on the integrated problem of operations sequencing and machine tools selection in the presence of the product mix and their production volumes. With the transitional costs among machining operations, the operation sequencing problem can be formulated as a well-known Traveling Salesman Problem (TSP). The transitional cost between two operations is expressed as the sum of total machining time of the parts on a machine for the first operation and transportation time of the parts from the first machine to a machine for the second operation. Therefore, the operation sequencing problem formulated as TSP cannot be solved without transitional costs for all operation pairs. When solved separately or serially, their mutual optima cannot be guaranteed. Machining operations sequencing and machine tool selection problems are two core problems in process planning for discretely machined parts. In this paper, the interrelated two problems are integrated and analyzed, zero-one integer programming model for the integrated problem is formulated, and the solution methods are developed using a Tabu Search technique.

• 복식문화연구
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• 제15권5호
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• pp.749-759
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• 2007

As the traditional style is treated as one of the important themes in fashion recently, how to apply the formative character in Korean and Japanese traditional dress to modern fashion is searched through actual analysis of photograph material, Both design formative elements were confirmed by clothing and fashion department majors through visual data so that 20 pieces of them were selected as final analysis object. Korean traditional dress form in modern fashion emphasizes curvaceousness as plane division. On the other hand, that of Japanese shows straight line, layered, belt, big look through up & down connection style. Color in Korean traditional dress prefers white and original color and modern fashion displays the natural beauty through harmony of similar colors ; that of Japanese based on natural color such as persimmon color cherishes natural beauty and implicit moderation showing harmony of various original color with brilliance and neutral color. While texture in Korean traditional dress was fine and exquisite, that of Japanese preferred coarse and tactile ones. In motif, Korea was natural and geometric but Japanese variously used complex and geometric ones. Likewise, the result suggests that the formative character in Korean and Japanese modern fashion affects the modern dress format as new aesthetic sense and takes on more complicated and subtle aspect in basic form, not just use so far.

• 한국생산제조학회지
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• 제23권1호
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• pp.1-6
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• 2014

This paper describes a method of estimating and evaluating the volumetric errors of multi-axis machine tools. The estimation method is based on a generic model that was developed from conventional kinematic error models for the geometric and thermal errors to help predict the volumetric error easily in various configurations. To demonstrate the advantages of the model, an application in the early stages of a five-axis machine tool design is presented as an example. The model was experimentally evaluated for a four-axis machine tool by using the data from ISO230-6 and R-test measurements to compare the estimated and measured volumetric errors.

• 한국유체기계학회 논문집
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• 제2권2호
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• pp.64-73
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• 1999

The three-dimensional numerical study of a water jet pump was carried out to investigate the relationship between performance and the geometric variables of nozzle space, area ratio, and throat length. Because of the complex geometry, the multiblock technique was adopted for numerical analysis and a special treatment for transferring data from each of the block interfaces was implemented in order to maintain the conserved properties. To validate the present code, flow passing through a square duct with a 90-deg bend was computed, our results show good accordance with other experimental and computational results. The numerical simulation was done with the flow of the water jet pump having a 180-deg bend in order to calculate the performance at different operating conditions. The performance of the water jet pump can be improved by study of parameters which clarify the relations between the geometric variables and the flow characteristics of vortex strength and location.

• 한국전산구조공학회논문집
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• 제22권2호
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• pp.163-172
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• 2009

3차원 패러매트릭 기반 솔리드모델링 방법으로 형상을 표현하고 건설산업분야에서 요구되는 다양한 정보를 처리할 수 있는 BIM기술은 2차원 도면의 자동생성, 건축요소들간의 간섭검토와 물량산출 이외에도 건물내 외 공간분석 및 관리, 구조해석 및 설계, 에너지 분석, 즉시조달, 시설물 및 재난 관리, 법규검토 등을 위한 고급 엔지니어링 업무까지 지원할 수 있게 한다. 본 논분은 이러한 IFC기반 BIM 기술을 건설분야의 각 임무에 작용하기 위하여 근원이 되는 각 건물요소의 기하형상을 추출하기 위한 연구내용을 제시하고 구현된 프로그램에 의한 적용사례를 보여준다.

• 한국전산유체공학회지
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• 제17권4호
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• pp.75-80
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• 2012

Due to the effect of surface tension, liquid film around a curved edge of solid surface moves from the corner to the flat surface. During this behavior of liquid film, film sagging phenomenon is easily occurred at the solid surface. Behavior of liquid film is determined with the effects of the properties of liquid film and the geometric factors of solid surface. In the present study, 2-D transient CFD simulations were conducted on the behavior of liquid film around a curved edge. The two-phase interfacial flow of liquid film was numerically investigated by using a VOF method in order to predict the film sagging around a curved edge. In the steady state of behavior of liquid film, the liquid film thickness of numerical result showed a good agreement with experimental data. After verifying the numerical results, the characteristics of behavior of liquid film were numerically analyzed with various properties of liquid film such as surface tension coefficient and viscosity. The effects of geometric factors on film sagging were also investigated to reduce the film sagging around a curved edge.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1663-1666
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• 2007

The finite element method is applied to analyze the deformation mechanisms in the closed-cell Al foam under the compression. The modeling of the real cellular structure proceeds with the concept of the reverse engineering. First of all, the small, $10{\times}\;10{\times}\;10mm^3$ sized specimens of the closed-cell Al foam are prepared. The micro focus X-ray CTsystem of SHIMADZU Corp. is used to scan the full structures of the specimens. The scanned structures are converted to the geometric surfaces and solids through the software for 3-D scan data processing, RapidFormTMof INUS Tech. Inc. Then the solid meshes are directly generated on the converted geometric solids for the finite element analysis. The large elastic-plastic deformation and 3-D contact problems for the Al cellular material are considered. The clear and successful analysis for the deformation mechanisms in the closed-cell Al foam is carried out through the comparison of the numerical results in this research with the referred experimental ones.