• 소성∙가공
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• 제8권4호
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• pp.347-355
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• 1999

The paper is concerned with an improved scheme for application of the blank holding force in order to take account of the thickness distribution in the sheet material of the flange region. The scheme incorporates with a modified membrane finite element method for planar anisotropic materials. The new scheme proposed two coefficients α and βto calculate the compressive stress in the sheet metal due to the blank holding force, which should be determined properly for accurate analysis. The effect of αand βon the blank holding force distribution and the deformed shape is investigated with simulation of rectangular cup deep drawing processes by changing parameter values.

• 소성∙가공
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• 제3권1호
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• pp.84-96
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• 1994

Simulation of 3 dimensional large irregularly shaped stamping process by a dynamic approach, based on an explicit time integration scheme, has been shown to be highly efficient and robust in comparison to traditional, implicit, quasi-static ones. The objective of the work is to evaluate the results from explicit code in application to deep drawing of rectangular cup and stamping of automotive front fender, in which deformation, force, thickness distribution are calculated. The method of predicting spring back and formability by and explicit code are suggested and applied to the processes.

• 소성∙가공
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• 제9권3호
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• pp.284-292
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• 2000

Optimization of the process parameters is carried out for process design in sheet metal forming processes. The scheme incorporates with a rigid-plastic finite element method for the deformation analysis and response surface methodology for the optimum searching of process parameters. The algorithm developed is applied to design of the draw bead force and the die radius in deep drawing processes of rectangular cups. The present algorithm shows the capability of designing process parameters which enable the prevention of the weak part of fracture during processes.

• 한국기계가공학회지
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• 제7권4호
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• pp.31-36
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• 2008

Sheet metal forming has some merits that are less loss of materials in process, less time-consuming and it makes mass product possible. The product produced by sheet metal forming process has high strength compared to the weight and better surface characteristics. Therefore, sheet metal forming process is a lot used in automobiles, aircrafts, electronics and appliances. This paper made the process design for forming Bracket Front Back Frame Lower, determined the blank shape and size using PAM-STAMP, commercial software and evaluated formability. It has been proved that the optimal blank through the result forming analysis has advantage in terms of formability and spring back compared to the rectangular blank.

• 대한교통학회지
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• 제12권2호
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• pp.31-45
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• 1994

One of the significant problems in urban areas is lack of parking spaces. Therefore, maximizing the number of cars that can be parked in a given area becomes increasingly important as land costs increase. This paper presents a methodology of optimal parking lot design in relatively small areas. The discussion is limited to self-parking surface rectangular lots. The selection of stall dimensions and aisle widths is based on the regulations of parking lot design standards of Korea. A personal computer software, OPALD, was developed and implemented to design optimal parking lots. OPALD iterates angles of parking stalls from 45 to 90 degree, generates the combination of paring angles, and selects the best angles to fit the given area. A drawing data file is also generated to draw layouts of parking lots in the CAD pakage (AutoCAD). Application of OPALD shows good results to design parking lots in relatively small areas. By-products of this research represents the parking modules of various angles.

• 건축역사연구
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• 제30권2호
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• pp.19-28
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• 2021

The purpose of this study is to research about the construction of Chiseong around the Heunginjimun Gate area in the 18th century. the conclusions derived from the historical evidence of the number, location, size, and form, and construction method of Chiseong was as follows. First, the Chiseong(Square-shaped lookout) of Hanyangdoseong was built in the 29th year of King Yeongjo(1753) and can be found in the national record. Five sites of the Chiseong are currently identified. It is assumed that the Foru was installed on top of some of the Chiseongs. Second, Chiseong was destroyed sequentially in the first half of the 20th century. Third, Chiseong is a rectangular in shape and six are constructed. Fourth, Sixth Chiseong could figure out through Hengryeopungsokdo, the drawing of Jeong Seon.

• 한국산학기술학회논문지
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• 제18권6호
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• pp.330-335
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• 2017

최근 자동차 산업에서 전기 모터 연료 전지에 대한 수요가 급증했으며, 연료 전지 케이스로 사용되는 사각형 알루미늄 캔에 대한 수요 또한 증가하고 있다. 직사각형 배터리 케이스의 바닥에 있는 에어 벤트는 비정상적으로 높은 압력이 발생할 때 미리 압력을 방출하여 큰 폭발을 방지하는 역할을 한다. 직사각형 컵 배터리 케이스는 6 단계의 다단계 딥 드로잉으로 외형을 만들고 직사각형 배터리 케이스와 용접하여 벤트 부품을 제작해왔다. 그러나 본 연구에서는 직사각형 케이스의 바닥면에 공기 벤트 형상을 직접 추가 하는 연구를 수행하였다. 단조의 초기 형상으로는 사각 컵 다단식 딥 드로잉 성형 해석에서 추출한 두께와 형상을 이용한 유한 요소 해석 기법을 사용 하였다. 그 결과, 예측 정밀도가 향상되고, 배부름 및 파단 등의 결함을 미리 예측할 수 있었다. 초기 분석 결과를 토대로 두 가지 단조 형상이 후보로 제시되었고 성형 해석을 통해 최적의 단조 형상을 결정 하였다. 이러한 결과를 바탕으로 금형을 제작하고 실제 결과와 분석 결과를 비교하여 본 연구의 타당성을 검증하였다.

• 한국정보처리학회논문지
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• 제6권11호
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• pp.3140-3149
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• 1999

Skew correction for document images can be using a rotational transformation of pixel coordinates. In this paper we propose a method which corrects the document skew, by an amount of $\theta$ degrees, using block information, where the block is defined as a rectangular area containing adjacent black pixels. Processing speed of the proposed method is faster than that of the method using pixel transformation, since the number of floating-point operations can be reduced significantly. In the proposed method, we rotate only the four corner points of each block, and then identify the pixels inside the block. Two methods for inside pixel identification are proposed; the first method finds two points intersecting the boundary of the rotated block in each row, and determines the pixels between the two intersection points as the inside pixel. The second method finds boundary points based on Bresenham's line drawing algorithm, using fixed-point operation, and fills the region surrounded by these boundaries as black pixels. We have measured the performance of the proposed method by experimenting it with 2,016 images of various English and Korean documents. We have also proven the superiority of our algorithm through performance comparison with respect to existing methods based on pixel transformation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 추계학술대회논문집
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• pp.93-97
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• 1997

Since the modified membrane element has the same external appearance as the ordinary membrane element, it is not able to apply the thickness variation of sheet metal in the blank holder to the contact treatment and the equally distributed blank holding force should be inevitably imposed on sheet metal along the periphery regardless of the contact status. But sheet metal does not contact with the blank holder at the periphery, nor the blank holding force is distributed uniformly along the boundary. To impose the blank holding force properly, the scheme is improved so that the blank holding force at each node imposed on sheet metal is dependent on the calculated thickness derivation and a state of equilibrium with the total blank holding force. The validity of the improved scheme is demonstrated with the simulation of cylindrical and rectangular cup deep drawing.

• 대한조선학회지
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• 제2권1호
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• pp.15-19
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• 1965

The stability curves are very important data to decide the seaworthiness of all kinds of ships among waves. Both statical and dynamical stability curves on a rectangular coordinate system have broadly been handled at ship yards or at the government concerned, up to data. As concerns a method of obtaining a statical stability curve on polar coordinate system, the papers were presented once. Also, it is of use to research the dynamical stability curve on polar coordinate system. Author treated of the dynamical stability curve by four different methods, and tried to set the stability indicator inboard, adopted those proposals, in order to give some aids for good navigation on the sea. Fig. 1. shows a drawing method in case of the position of centre of buoyancy can be previously pointed out on the line corresponding to its inclination. Fig. 2. shows a method used a statical stability curve on polar coordinate. Fig. 3. shows a method obtained by the most simplified means. Fig. 4. shows dynamical stability curve made by geometrical expression method, instead of dynamical lever. A simple stability indicator which was mechanized above characteristics is attempted by author as shown Fig. 5 and Fig.6. It is demanded at hand, for more advanced improvement of such indicator.