• International Journal of Fuzzy Logic and Intelligent Systems
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• 제6권2호
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• pp.144-149
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• 2006

This paper describes a novel automated analysis system for bellows of piping system. An automatic finite element (FE) mesh generation technique, which is based on the fuzzy theory and computational geometry technique, is incorporated into the system, together with one of commercial FE analysis codes and one of commercial solid modelers. In this system, a geometric model, i.e. an analysis model, is first defined using a commercial solid modelers for 3-D shell structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay triangulation technique is introduced as a basic tool for element generation. The triangular elements are converted to quadrilateral elements. Practical performances of the present system are demonstrated through several analysis for bellows of piping system.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제6권1호
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• pp.58-63
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• 2006

This paper describes a novel automated analysis system for bellows of piping system. An automatic finite element (FE) mesh generation technique, which is based on the fuzzy theory and computational geometry technique, is incorporated into the system, together with one of commercial FE analysis codes and one of commercial solid modelers. In this system, a geometric model, i.e. an analysis model, is first defined using a commercial solid modelers for 3-D shell structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay triangulation technique is introduced as a basic tool for element generation. The triangular elements are converted to quadrilateral elements. Practical performances of the present system are demonstrated through several analysis for bellows of piping system.

• 대한기계학회논문집
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• 제18권9호
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• pp.2404-2412
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• 1994

A mathematical model has been developed for predicting kinematic, thermal, and solidification histories of atomized droplets during flight. Liquid droplet convective cooling, recalescence, equilibrium-state solidification, and solid-phase cooling were taken into account in the analysis of the solidification process. The spherical shell model was adopted where the heterogeneous nucleation is initiated from the whole surface of a droplet. The growth rate of the solid-liquid interface was determined from the theory of crystal growth kinetics with undercooling caused by the rapid solidification. The solid fraction after recalescence was obtained by using the integral method. The thermal responses of atomized droplets to gas velocity, particle size variation, and degree of undercooling were investigated through the parametric studies. It is possible to evaluate the solid fraction of the droplet according to flight distance and time in terms of a dimensionless parameter derived from the overall energy balance of the system. It is also found that the solid fraction at the end of recalescence is not dependent on the droplet size and nozzle exit velocity but on the degree of subcooling.

• 대한기계학회논문집B
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• 제27권5호
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• pp.635-643
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• 2003

Parametric study for the analysis of performance characteristics of a planar -type solid oxide fuel cell(SOFC) using computational flow analysis is conducted. A planar -type SOFC, which is composed by two gas channels (fuel and ai.) and one set of anode-electrolyte-cathode assembly, is modeled as a two -dimensional isothermal case. Results of computational analysis of flow field including distributions of mass fractions in gas channels are used to the performance analysis of the fuel cell. Flow analysis makes it possible to consider current density distributions along the length of the cell in the process of performance analysis of the SOFC. As results of parametric study, it is found that the mole fraction of fuel at the inlet of fuel channel, operating pressure and temperature are closely related to the performance characteristics of SOFC.

• 한국정밀공학회지
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• 제20권11호
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• pp.180-187
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• 2003

A CAD-based seamless design system for MEMS named DS/MEMS was developed which performs coupled-field analysis, optimal and robust design. DS/MEMS has been developed by means of integrating commercial codes and inhouse code-SolidWorks, FEMAP, ANSYS and CA/MEMS. This strategy results in versatility that means to include various analysis model, corresponding analyses and approximated design sensitivity analysis and user friendliness that design variables are taken to be selectable directly from a CAD model, that the problem is formulated under a window environment and that the manual job during optimization process is almost eliminated. DS/MEMS works on a parametric CAD platform, integrating CAD modeling, analysis, and optimization. Nonlinear programming algorithms, the Taguchi method, and response surface method are made available for optimization. One application problem is taken to illustrate the proposed methodology and show the feasibility of DS/MEMS as a practical tool.

• 한국건축시공학회지
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• 제16권6호
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• pp.579-585
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• 2016

3차원 이미지 스캐닝 기술은 복잡한 비정형 건축물의 외피의 정확한 형상과 위치 데이터를 확보하는데 효과적이다. 3차원 이미지 스캐닝 기술의 세부 과정인 점 군집화, 메쉬표면 분리, 넙스 표면 생성, 파라메트릭 솔리드 모델을 통하여 비정형 건축물의 형상을 구축할 수 있다. 이에 본 연구는 비정형 건축물의 외장재 제작과 시공을 위한 3차원 이미지 스캐닝에 의한 역설계 프로세스와 사례 분석을 통하여 시사점을 도출한다. 본 연구의 결과는 역설계 기술을 사용한 3차원 형상 기술과 설계 요소화 방법을 다양한 건설 프로젝트에 활용할 수 있을 것으로 판단된다.

• 대한기계학회논문집B
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• 제28권7호
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• pp.747-754
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• 2004

Thermo-fluid characteristics in coke oven, sintering machine and blast furnace in iron-making facility are key processes related to the quality and productivity of the pig iron. Solid material in the processes usually forms a bed in a gas flow. For simulation of the processes by mathematical model, the solid beds are idealized to be a continuum and a reacting solid flow in the gas flow. Governing equations in the form of partial differential equations for the solid material can be constructed based on this assumption. Iron ore sintering bed is simulated and limited amount of parametric study have been performed. The results have a good agreement with the experimental results or physical phenomena, which shows the validity and applicability of the model.

• Computers and Concrete
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• 제33권6호
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• pp.643-658
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• 2024

To date, shell-solid and fibre element model analysis are the most commonly used methods to investigate the seismic performance of concrete-filled steel tube (CFST) bridge piers. However, most existing research does not consider the loss of bearing capacity caused by the fracture of the outer steel tube. To fill this knowledge gap, a refined finite element (FE) model considering the ductile damage of steel tubes and the behaviour of infilled concrete with cracks is established and verified against experimental results of unidirectional, bidirectional cyclic loading tests and pseudo-dynamic loading tests. In addition, a parametric study is conducted to investigate the seismic performance of CFST bridge piers with different concrete strength, steel strength, axial compression ratio, slenderness ratio and infilled concrete height using the proposed model. The validation shows that the proposed refined FE model can effectively simulate the residual displacement of CFST bridge piers subjected to highintensity earthquakes. The parametric analysis indicates that CFST piers hold sufficient strength reserves and sound deformation capacity and, thus, possess excellent application prospects for bridge construction in high-intensity areas.

• 한국의류학회지
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• 제43권3호
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• pp.373-383
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• 2019

This research investigated the effect of individual yarn colors on the perception of overall colors of yarn-dyed woven fabrics. The way the colors of yarn-dyed woven fabrics are perceived is known as visual color mixing: when the different colored yarns juxtaposed on the fabric surface are observed from some distance away, they are visually mixed in our eyes and perceived as a solid color. However, we can still see individual yarn colors that make the fabrics look obviously different from actual solid colors. To quantify this visual color mixing effect, twenty-one sateen fabrics were produced in a wide range of colors using cyan, magenta, and yellow yarns, and the colors were measured instrumentally. The obtained colorimetric values were converted into solid color images on a CRT monitor. Then, the physical fabrics were scanned, and the scanned images were displayed on the monitor with solid color images in pairs for visual color difference evaluation. The woven and solid colors in each pair were of physically identical color; however, the visual color difference was as large as $4.81{\Delta}{E^*}_{ab}$ on average. A visual color difference model was proposed by considering this parametric effect of individual yarn colors.

• 한국가스학회지
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• 제2권3호
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• pp.25-36
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• 1998

석유화학산업에서는 많은 복잡한 공정과 고온, 고압으로 가연성과 반응성을 가진 화학물질을 사용$\cdot$저장하고 있기 때문에 화재 및 폭발사고의 가능성이 잠재하고 있다. 화학공장은 특성상 BLEVE (Boiling Liquid Expanding Vapor Explosion)와 Fireball이 일어날 가능성이 높다. 본 연구에서는 BLEVE와 Fireball에 의한 폭발 영향평가를 위하여 모델을 제시하고 피해를 예측 할 수 있는 컴퓨터 프로그램을 개발하였다. BLEVE는 단열 팽창 모델, 등온 팽창 모델, 물리적 폭발모델을 Fireball은 Solid 모델을 사용하였으며 모델의 매개변수의 민감도를 분석하였다. 또한, 벤젠, 톨루엔, 메타-자일렌의 BLEVE와 Fireball에 의한 폭발량 등의 피해를 산정하였다.