• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.249-254
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• 2000

The contact forces between die components for the drawing of large size automotive panels introduce elastic deflections of the die components. Due to the deflections, the gap between blank holder and die varies locally resulting in nonuniform material flow. Such a nonuniform die gap usually requires correcting operation, so called die spotting, which is time consuming trial and error process. To reduce the die spotting time, the optimization of the blank holder bending deflection is needed. In this paper, we implemented an analysis procedure to predict the blank holder deflection. The analysis procedure and design of experiments techniques are applied to the optimization of balance block heights. The optimization results can be used as guidelines in actual die spotting process.

• 소성∙가공
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• 제8권6호
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• pp.541-553
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• 1999

Cold forging is a special type of forging process in which metal is forced to flow plastically under compressive force into a variety of shapes in room temperature. Gear blank, which is produced by cold forging, is concerned with the production method of transmission gear. Based on the results of simulation of the current four-stage process, the gear blank forging process for improving the conventional process sequence is designed. The rigid plastic finite element analysis for improving the conventional process. The new process consists of three stage operations with one annealing treatment after first operation. Based on the results of simulation of the proposed process, a required equipment could be selected. The new designed process appears to be more economical in producing the gear blank.

• 소성∙가공
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• 제5권4호
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• pp.281-287
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• 1996

Two kinds of blank shapes optimum and square are adopted to investigate formability. Optimum blank shape is determined to construct an L-shape cup with uniform height and without flange part. For this purpose rigid-plastic FEM analysis is applied with backward tracing technique. Maximum cup depth and strain distribution are measured experimentally for the products of the two kinds of blank shapes which are optimum and square. it is confirmed that deeper cup without severe thickness reduction can be obtained from the optimum shape.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 제2회 박판성형심포지엄 논문집 박판성형기술의 현재와 미래
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• pp.102-109
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• 1998

In this study, the side panels were developed using the laser-welded Tailored Blanks (TB) with both the same thickness and the different thickness. At first, the formability of the same thickness T.B was investigated to be compared with one of the non welded panel with respect to weldline movements and strain distribution on blank during the stamping. Based on these results, we selected candidates of T.B with different thickness for stamping experiments. That is, we determined the weld line positions and the die step. Then we made some stamping tryouts with selected types of blank designs to investigate the formability of T.B with different thickness. During the tryouts, the wrinkles were found in the a-pillar lower region which is under the deformation mode of the shrink flange. In the b-pillar region, the fractures were found also, these defects have been reduced and corrected by controlling the blank design and the die faces and process pamameters.

• 소성∙가공
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• 제25권6호
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• pp.396-401
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• 2016

Recently, Multi-strength hot stamping process has been widely used to achieve lightweight and crashworthiness in automotive industry. In concept of multi-strength hot stamping process, process design of tailor rolled blank(TRB) in partial heating is difficult because of thickness and temperature variation of blank. In this study, springback prediction of TRB in partial heating process was performed considering its thickness and temperature variation. In partial heating process, TRB was heated up to $900^{\circ}C$ for thicker side and below $Ac_3$ transformation temperature for thinner side, respectively. Johnson-Mehl-Avrami-Kolmogorov(JMAK) equation was applied to calculate austenite fraction according to heating temperature. Calculated austenite fraction was applied to FE-simulation for the prediction of springback. Experiment for partial heating process of TRB was also performed to verify prediction accuracy of FE-simulation coupled with JMAK equation.

• 한국게임학회 논문지
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• 제15권5호
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• pp.39-48
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• 2015

온라인 FPS 게임 개발과 서비스가 활발하게 이루어지고 있는 반면에 FPS 레벨 디자인 관련 연구는 부족한 실정이다. 기존에 FPS 레벨 디자인 연구는 주로 PVE을 중심으로 이루어졌으나, 온라인 FPS 게임에서는 PVP 레벨 디자인 시각에서 살펴볼 필요가 있다. 이에 본 연구에서는 포인트 블랭크(Point Blank) 단체전 선호 레벨을 사례로 PVP 레벨 디자인과 PVE 레벨 디자인 패턴을 비교해 보았다. 본 연구는 사례 분석 결과 및 세 명의 FPS 개발 전문가 인터뷰를 통해 PVP 레벨 디자인 패턴 분류를 제시했다는 점에서 의의가 있다.

• 대한토목학회논문집
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• 제39권4호
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• pp.513-521
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• 2019

본 연구의 목적은 지하철 이용자의 지하철 표지 여백에 대한 특성의 군집그룹별 선호도를 파악하는 것이다. 세부적으로 성별, 연령 등의 특성에 따라 지하철 표지 여백에 대한 특성을 다양하게 디자인하는 개념을 도입하는 것을 목적으로 한다. 본 연구는 지하철 표지 여백에 대한 특성의 선호도를 조사하고 전체그룹과 군집그룹별 선호도를 분석하였다. 선호도 조사를 위해 설문조사를 실시하였으며, 선호도 분석을 위해 군집분석을 실시하고 전체그룹과 군집그룹의 인구통계학적 분석과 컨조인트 분석을 실시하였다. 선호도 조사를 위한 지하철 표지 여백에 대한 특성의 속성은 상하여백, 측여백, 테두리선 여백, 화살표 두께, '역명'과 '호선번호' 순서로 설정하였다. 선호도 분석 결과는 다음과 같다. 전체그룹에서 속성의 중요도는 테두리선 여백, '역명'과 '호선번호' 순서, 측여백, 상하여백, 화살표 두께 순으로 나타났다. 군집그룹은 총 3개의 그룹으로, 1군집은 지하철을 거의 매일, 일주일에 3~4회 이용하는 여성으로, 글자의 1/2 측여백을 선호하는 것으로 나타났다. 2군집은 60대 이상의 지하철 표지를 불편하다고 생각하는 이용자로, 테두리가 없는 것과 '역명'+'호선번호' 순서를 선호하는 것으로 나타났다. 3군집은 20대와 30대의 남성으로, 글자의 1/5 테두리선 여백과 얇은 화살표 두께를 선호하는 것으로 나타났다. 결론은 다음과 같다. 첫째, 지하철 표지 여백에 대한 특성을 일관성 있게 디자인 해야하지만, 특정지역 혹은 노선에 대해서 성별, 연령별, 지하철 이용횟수에 따라 다양하게 고려할 필요성이 제시되었다. 둘째, 특정지역 혹은 노선에 따라서는 지하철 표지 여백에 대한 특성의 표지를 표준화된 한 가지 유형이 아닌 두 가지 이상의 유형의 디자인이 가능함을 보여주었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.179-182
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• 1997

One-step inverse methods based on deformation theory causes some amount of error. The amount of error is generally increased as the deformation path is more complex. As a remedy, a new three dimensional multi-step inverse method is introduced for optimum design of blank shapes and strain distributions from desired final shapes. The approach extends a one-step inverse method to a multi-step inverse method in order to reduce the amount of error. The algorithm developed is applied to square cup drawing to confirm its validity by demonstrating reasonably accurate numerical results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1996년도 추계학술대회논문집
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• pp.174-184
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• 1996

Two methods for cold extrusion processes to produce an axisymmetric steel gear blank are investigated for comparing each other. The "classical" forming method consisting of four operations is selected first to be simulated using the rigid-plastic finite element method and uses single-die presses. The other using a fully automated transfer headers can produce the final part without interannealing. The final products must be checked at the design criteria such as area reduction, the extrusion ratio and punch diameter to depth ratio, especially punch buckling by simulations. FEM analysis is performed mainly for strain distribution, both process sequences are proved to have proper charicteristics suitable for each production method in terms of maximum load. Those simulation results will provide good design criteria in the future work to advance the manufacturing process.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 추계학술대회논문집
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• pp.65-71
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• 1997

Computer simulations and test trials are carried out to get the optimal conditions about the stamping die design of the tailor laser welded automotive door inner. Firstly, the stamping process including gravity deflection, bead calibration, binder wrap, forming and spring back, are analyzed by the computer simulation. The results of simulation shows good correspondance with those of test trial under the same conditions. The variables of parametric study which will be investigated in the simulation and test trials, are determined form the results of the first run. The formability under the various conditions is evaluated, which are the initial postion of blank, blank holding force, corner radius and the shape of drawbead. Finally, well controled sound product without fracture, wrinkling and excessive weldline movement is obtained.