• 전산구조공학
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• 제3권3호
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• pp.39-47
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• 1990

본 고에서는 현재 국내 원전설계시 원용되고 있는 미국의 원전내진설계 관련규준의 구성체계를 훑어본 다음, 최근 대폭 개정된 절차를 중심으로 그 배경 및 세부내용을 소개하고, 이들 개정내용이 설계결과에 미칠 영향을 분석하고자 한다.

• 한국정밀공학회지
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• 제15권2호
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• pp.21-27
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• 1998

NC machining of large screw which is usually used as a part in an extruder for injection molding is done on 3-axis turning machine, and it is very time-consuming process. Not only in machining but in preparing part program for a NC machine, it requires very long time because the shape of the screw is not easy to model when using an existing general CAD/CAM software even though it is workstation level software. In addition, tool path generation procedure for NC turning for screw shape is also very tedious one because large amount of data for cutter location point must be produced and there is no specific CAM software for the machining. In this paper. development of a CAM system for screw machining which saves the role of CAD software by use of menu driven data input system for various screw shapes is introduced.

• 한국정밀공학회지
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• 제20권10호
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• pp.156-163
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• 2003

This research presents modeling of a functional surface which is a constructed free-formed surface. The modeling introduced in this paper adopts modified B-spline that is utilizing approximating technique. The modified B-Spline is constructed with altered control vertices. It is applied to measure points on a surface of an impeller blade. This research builds a surface-modeler accepting inputs of measured points. Generation of cutter-paths for NC machining employs the model of the constructed surfaces. The machined surfaces which is generated in several cases are compared in the aspect of machining accuracy.

• 한국정밀공학회지
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• 제17권10호
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• pp.26-34
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• 2000

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.318-321
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• 2007

This paper is concerned with improvement of surface quality of a sheet metal member in the stamping process. The CAE procedure of the stamping process is utilized in order to investigate cause of surface troubles and to improve surface quality. A complicated shape of the sheet metal member can induce surface troubles such as wrinkles because of insufficient tensions force and non-uniform contact of a blank sheet with tools. This paper proposes two guidelines such as a change of tool shape and added draw-beads on the tool surface in order to increase tension forces and to induce uniform contact. The proposed guidelines are verified with the CAE of the stamping process. The CAE results show that the changed shape of tools and added draw-beads can reduce the amount of wrinkles and improve surface quality.

• 한국전산구조공학회논문집
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• 제12권4호
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• pp.607-618
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• 1999

유한요소법의 강의와 학습을 지원하는 컴퓨터 기반 교육시스템(computer-based training system)을 개발하였다. 이 시스템은 유한요소해석을 요소 모델링에서부터, 최종결과의 계산에 이르기까지 여러 개념과 과정을 가시화하고, 사용자가 직접 상호작용 적으로 실습하고, 해석과정에 개입하여 모의 조작(simulation)하며, 그 반응을 관찰할 수 있는 여러 기능을 갖추고 있다. 이 시스템을 이용하여 실제적인 유한요소해석을 실행 할 수 있다. 따라서 이 시스템을 유한요소법의 보조 교육 재료로 활용할 뿐만 아니라 실제적인 유한요소해석 소프트웨어로 병용함으로써 유한요소법의 교육과 학습의 효과를 높일 수 있다.

• 한국자동차공학회논문집
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• 제13권3호
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• pp.64-73
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• 2005

This paper is concerned with the simulation-based parameter determination for the tool design in the stamping process of the complicated auto-body member. The CAE procedure of the stamping process is proposed so that troubles such as wrinkle, springback and excess metal be eliminated with changing parameters such as the blank size, the restraining force of the draw-bead and the embossing shape in the die face. The selected indicators of failure during forming are wrinkling. the amount of spring after unloading of the tool, the amount of excess metal developed .The proposed analysis scheme is applied to the tool and process parameter design for the front side member of a RV car. The simulation results show that the scheme can produce sound product from the viewpoint of thickness distribution, the contact condition between tools and the blank, the shape accuracy and so on.

• 한국자동차공학회논문집
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• 제12권3호
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• pp.109-121
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• 2004

This paper presents an optimal design method for structure-borne durability of a vehicle body structure. Structure-borne durability design requires a new design that can increase fatigue lives of critical areas in a structure and must prohibit transition phenomenon of critical areas that results from modification of the structure at the same time. Therefore, the optimization problem fur structure-borne durability design are consists of an objective function and design constraints of 2 types; type 1-constraint that increases fatigue lives of the critical areas to the required design limits and type 2-constraint that prohibits transition phenomenon of critical areas. The durability design problem is generally dynamic because a designer must consider the dynamic behavior such as fatigue analyses according to the structure modification during the optimal design process. This design scheme, however, requires such high computational cost that the design method cannot be applicable. For the purpose of efficiency of the durability design, we presents a method which carry out the equivalent static design problem instead of the dynamic one. In the proposed method, dynamic design constraints for fatigue life, are replaced to the equivalent static design constraints for stress/strain coefficients. The equivalent static design constraints are computed from static or eigen-value analyses. We carry out an optimal design for structure-borne durability of the newly developed bus and verify the effectiveness of the proposed method by examination of the result.

• 한국정밀공학회지
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• 제28권3호
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• pp.349-356
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• 2011

This paper replaces a conventional austenitic stainless steel sheet to a ferritic stainless steel for the cost reduction of a pulsator cover of a washing machine. However, ferritic stainless steel has poor formability in comparison with austenitic one. The low formability of ferritic steel results in problems during stamping such as fracture, wrinkling, shape inaccuracy and so on. Design modification of the stamping tool is carried out with the aid of the finite element analysis for multistage stamping process of the pulsator cover. The simulation results show that fracture occurs on top of the product while wrinkles are generated by the excess metal near the wing part. Modification of the initial stamping die is performed to improve metal flow and to eliminate problems during the stamping process. Simulation with the modified design fully demonstrates that safe forming is possible without inferiorities.

• 한국정밀공학회지
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• 제17권6호
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• pp.83-88
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• 2000

In machining large screws such as those of extruders, it takes long time to machine them on conventional machines which usually use single-tipped fixed tools. And it is also difficult to use an existing CAD/CAM coftware when trying to get over the problems of conventional machines and making use of CNC machines. In this paper, generation of machining program using rotational tools for large screws defined by longitudinal-section profile is descrebed. Use of rotational tools in machining plays an important role in saving machining time. In the sort of extruder screws, it is easy to define a screw shape by longitudinal-section profile, and by which improvement of dimensional accuracy can be expected. The CAM software developed in this paper is based on user's and designer's friendliness.