• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.185-195
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• 1998

A new blank design method is proposed to predict the optimum initial blank shape in the sheet metal forming process. The rollback method for blank shape design takes the difference between final deformed shape and target contour shape into account. Based on the method, a computer program composed of blank design module, FE-analysis program and mesh generation module is developed. The rollback method is applied to square cup drawing process with the flange of unifiorm size around its periphery to confirm its validity. The optimum initial blank shape is obtained from an arbitrary square blank after three modifications. Good agreements are recognized between the numerical results and the published results for initial blank shape and thickness strain distribution. The optimum blank shape for two parts of automobile sub-frame is designed. The thickness distribution and the level of punch load is improved. Also, the method is applied to design the weld line in the tailor-welded blank. It is concluded that the rollback method is an effective and convenient method for an optimum blank shape design.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.86-91
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• 2005

The stack, the core unit of the MCFC system, is composed of the three main parts which are the electrodes, the matrix keeping the electrolyte and the separator. Among these, the separator made of low carbon steel is manufactured by some sheet metal forming processes. The flatness of flange of the mask plate of the separator is crucial not only to enhance the stack performance but also to reduce the production cost. This study has focused on the enhancement of flatness of the mask plate flange by controlling some process parameters like the punch and die comer radii, the blank holding force, the friction coefficient and so on. The springback phenomenon occurring in the flange drawing process has been studied first using the finite element method (FEM) in order to understand what causes the springback. The distribution pattern of local longitudinal stress in the flanged part has been revealed very important in predicting the final shape of the flange. This fact has been backed up by the experimental results carried out with the developed test dies.

• 대한기계학회논문집
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• 제16권4호
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• pp.684-695
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• 1992

본 연구에서는 3차원 형상의 금형에 의한 박판금속 성형 공정을 에너지법으로 해석함에 있어 스윕곡면(SWeep surface)을 통해 기하학적 형상을 효과적으로 표현하는 방법을 제안하고, 이를 직사각형 격막의 정수압벌징의 해석에 으용하여 이에 의한 결 과를 이미 보고된 자료와 비교함으로써 일반적인 박판 성형공정을 해석하는데 본 이론 의 적용 가능성에 대하여 논의하고자 한다.

• 대한기계학회논문집
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• 제13권6호
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• pp.1092-1103
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• 1989

본 논문에서는 기존의 금속성형의 유한요소해석에서 사용한 바 있는 기하적경 계조건을 직접 유한요소방정식에 대입하는 방법들을 비교검토하고 3차원박판성형에 적용하기 위하여 개선된 방법을 개발하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.557-561
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• 1997

In this study, using DEFORM and PAM-STAMP drawbead analysis is carried out for the commercial code availability. The three drawbead types, single circular drawbead, single square drawbead and double circular drawbead, are examined. The clamping force, drawing force and effective strain of sheet metal which is passed by drawbead are checked on each drawbeads.

• 한국정밀공학회지
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• 제6권4호
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• pp.103-107
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• 1989

The effects of annealing temperature on the magnetic properties (maximum permeability, coercive force and remanence) and mechanical properties (hardness, tensile strength and elongation at rupture) were analyzed using the nondestructive impulsive magnetic analyzer in a medium carbon cold rolled steel sheet. This nondestructive method was very useful for the analysis of magnetic and mechanical properties of materials. As it was known in the literature, the three distinct processes that indicate the recovery, recrystallization, and grain growth of a metal were measured with the non-destructive analyzer.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.163-168
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• 2000

In this paper, a 3-D computer-aided die design process was developed for automobile rear frame with drawing, trimming, flanging, cam-piercing and piercing for tool design. The tool design has been done using Pro/Engineer on a personal computer. It is composed of four stations. The goal of this research is to apply each of stations for the standard tool specification to each station.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 박판성형기술의 진보
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• pp.163-172
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• 1994

The Aerospace and automobile industries have need to avoid sheet-metal forming problem such as incorrect springback after forming and trimming process, excessive thinning/tearing, wrinking/perkering. It is common practice to use costly trial-and-error experimental methods to develop tooling and manufacturing process parameters. Experimentation should be complemented with computer simulation to reduce cost and leadtime in manufacturing and to influence the design of components. In this study, firstly we solved the springback problem after drawing and trimming process of KFP(F100-229) engine airsealing bearing support part(53H00) forming and studied on the effect of several process parameters on the gap between the formed blank and punch shape using the implicit F.E.M code(ABAQUS). Secondly by the three dimensional dynamic analysis using the explicit. F. E. M code (LS-DYNA3D), we studied on the effect of several process parameters which can be used for avoid tearing and wrinking during the drawing process.

• Advances in materials Research
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• 제2권4호
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• pp.181-193
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• 2013

Description and theory of spin coating technique has been elaborately outlined and a spin coating machine designed and fabricated using affordable components. The system was easily built with interdisciplinary knowledge of mechanics, fluid mechanics and electronics. This equipment employs majorly three basic components and two circuit units in its operation. These include a high speed dc motor, a proximity sensor mounted at a distance of about 15 mm from a reflective metal attached to the spindle of the motor to detect every passage of the reflective metal at its front and generate pulses. The pulses are transmitted to a micro-controller which process them into rotational speed (revolution per minute) and displays it on a lead crystal display (LCD) which is also a component of the micro-controller. The circuit units are a dc power supply unit and a PWM motor speed controlling unit. The various components and circuit units of this equipment are housed in a metal casing made of an 18 gauge black metal sheet designed with a total area of 1, $529.2cm^2$. To illustrate the use of the spin-coating system, ZnO sol-gel films were prepared and characterized using SEM, XRD, UV-vis, FT-IR and RBS and the result agrees well with that obtained from standard equipment and a speed of up to 9000 RPM has been achieved.

• 한국재료학회지
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• 제30권9호
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• pp.453-457
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• 2020

Tomb No. 1 (Donghachong) of the Buyeo Neungsan-ri Tomb complex (listed as UNESCO World Heritage Site), is a royal tomb of the Baekje Sabi Period. One wooden coffin unearthed there is an important relic of the funerary culture of the Baekje. This study examines the production techniques of gilt-bronze objects attached to the wooden coffin excavated from Donghachong. The base metal of the gilt-bronze object is pure copper, with single α phase crystals in a heterogeneous form containing annealing twins; Au and Hg are detected in the gilt layer. We suggest that the surface of the forging copperplate is gilded using a mercury amalgam technique; it is thought that the annealing twins of the base material formed during the heat treatment process for the sheet metal. The gilt layer is three to five times thicker for the gilt-bronze objects found near the foot of the coffin than those near the head. We estimate the plating process is carried out at least three times because three layers are identified on the plate near the head. Therefore, it is likely that the materials and methods used to construct the gilt-bronze objects found in different parts of the coffin are the same, but the number of platings is different. This research confirms the metal crafting techniques used in Baekje by the examination of production techniques of these gilt-bronze objects. Further, our paper presents an important example of restoration and reconstruction for a museum exhibition, through effective use of scientific analysis and investigation.