• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.195-198
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• 1995

In Semi-Solid Forging, it is necessary to control the forming variables accurately in order to make near-net-shape products. Generally, the defects of products may occur due to liquid segregation which can be caused by the degree of deformation and condition of friction in Semi-Solid Forging, where the segregation is to be predicted by flow analysis. This paper presents the feasibility of theoretical analysis model using the new yield function which is proposed by Doraivelu et al. to the flow analysis of the semi-solid dendritic Sn-15%Pb alloys instead of adopting the yield criterion of Shima & Oyane which is used by Charreyron and usefulness of the adopted yield function. The distribution of the liquid fraction at various strains in radial direction and the influence of friction are estimated by Upper Bound Method.

• 한국정밀공학회지
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• 제15권2호
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• pp.81-89
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• 1998

Numerical calculation tools for forging of gear-like components based on kinematically admissible velocity fields for upper bound method applicable to various deformation features of workpiece in forging processes were suggested. Each one of them deals with unidirectional flow of metal on dies, such as external involute spur gear. square spline, internal serrations. A complex calculation tool of gear-like component forging process was built up by combining these kinematically velocity fields. In this paper the workpiece with 110th external and internal teeth is divided into two parts. The deformation of each part is analyzed simultaneously using numerical calculation tool from combined kinematically admissible velocity field. The experimental set-up was installed in a 200 ton hydraulic press. As a result, each kinematically admissible velocity field could be combined with others and the calculated solution are useful to predict the capacity of forging equipment.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.261-268
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• 2000

In this study the bearing capacity of the eccentrically loaded shallow footing is estimated by means of the upper bound method of limit analysis. In the case of applying the upper bound, the results depend on the failure mechanism. So the failure surface is correctly studied through the model test using sand. New method is proposed to estimate the bearing capacity of the eccentrically loaded shallow footing by means of the upper bound method to apply the failure mechanism based on the model test. The propriety of new method is verified by the results of various methods. And the influences of the variables eccentricity, embedment depth, variations of contact width factor by model test using sand are also studied in this paper

• 대한기계학회논문집
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• 제19권5호
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• pp.1211-1219
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• 1995

An upper bound elemental technique (UBET) program has been developed to analyze forging load, die-cavity filling and effective strain distribution for flash and flashless forgings. The simulation for flash and flashless forgings are applied axisy mmetric and plane-strain closed-die forging with rib-web type cavity. Inverse triangular and inverse trapezoidal elements are used to analyze flashless forging. The analysis is described for merit of flashless precision forging. Experiments have been carried out with pure plasticine billets at room temperature. Theoretical predictions of the forging load and the flow pattern are in good agreement with experimental results.

• 한국정밀공학회지
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• 제14권6호
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• pp.142-148
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• 1997

In this paper, forging of internal triangular and involute serrations are analyzed by upper bound method. Kinematically admissible velocity fields for half pitch of the serration were proposed. It was assumed that the shape flow surface during forging is a straight line perpendicular to plane of symmetry. Using the suggested velocity fields, forging loads and relative pressures were calculated by numerical method. Experiments were carride out with commercial AI 2024 aluminium alloy. As a result, the calculated solutions are good agreement with experimental results, so it is useful to predict the loads for forging of internal serrations.

• 소성∙가공
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• 제4권3호
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• pp.257-266
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• 1995

A simulation method based on upper bound method is developed in order to characterize forging characters in forging of spur gears. In this paper, utilizing a kinematically admissible velocity field and applying it to investigate the effect of inner diameter of holow billet. In the analysis, to predict the variation of inner diameter of hollw billet, neutral surface has been introduced. The neutral surface of each step is assumed as a circle and determined in order to have minimum forging energy by golden section method. By this method, the variation of inner diameter of billet during spur gear forging is successfully predicted. As a result, the selection of inner diameter of initial billet is very important to reduce the forging load.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.183-186
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• 1995

A simulation method basee on upper bound method is developed in order to characterize forging characters in forging of spur gears. In this paer, utlizing a kinematically admissible velocity field and applying it to study the effect of inner diameter of holow billet. To predict the variation of inner diameter of hollow billet, neutal surface has been introduced into forging of hollow gears from hollow billes with flat punch. The neutral surface of each step is assumed as a circle and determined in order to have minimum forging energy by golden section method. According to the analysis, the magnitude of inner diameter of initial billet is vary important to reduce the relative pressure and forging load. And the variation of inner diameter of billet during spur gear forging is successfully predicted.

• 한국정밀공학회지
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• 제13권1호
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• pp.108-115
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• 1996

Forging of trapezoidal spline, serration and square spline with solid cylindrical billets and hollow one has been investigated by means of upper bound method. Kinematically admissible velocity fields for forging of splines have been proposed in this study. The half pitch of spline has been divided into several deformation regions. The neutral surface is introduced into forging of splines with flat punch and, for each step, it is assumed as a circle with its radius $r_n$. Upper bound solutions obtained by proposed kinematically admissible velocity fields are useful to predict the loads for forging of splines.

• 월간양계
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• 제48권1호
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• pp.129-131
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• 2016

부모 가업을 잇는 후계자들이 늘어나면서 양계인 2세대 경영인들의 조합 또는 조직화된 모임이 탄탄하게 결성돼 왕성히 활동하고 있다. 부모로부터 기술과 경영력을 물려받고, 축산 전문 교육 과정 수료 등 전문 지식 습득과 2세대 양계인들은 서로간의 정보 교류까지 더해져 보다 빠른 시대변화에 적응하고 경쟁력을 갖추고 있다. 산란계 분야에서는 2세대 법인 또는 조직적인 모임으로 대표적으로 경기도 광주 일대의 '다한영농조합법인'과 김포 일대의 '풍우동주'가 있으며 경상도 일대의 '대구경상계우회(이하 대경회)'가 요즘 핫한 산란계 2세대 양계인 모임이다. 2016년 신년을 맞아 대경회 회장이자 경북 칠곡군 소재 창일농장에서 부모의 가업을 이어 부모님과 함께 경영하는 이수고 대표를 만나 농장 운영과 대외 활동사항에 대해 인터뷰한 내용을 정리했다.

• 대한기계학회논문집
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• 제13권3호
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• pp.330-336
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• 1989

본 연구에서는 상계해법을 이용하여 축대칭 후방압출에 있어서 압출하중뿐 아니라 소성변형역의 형상 및 비유동영역(dead metal zone)까지 에측이 가능한 단순하고 체계적인 이론해석법을 제안하고 이에 대한 실험을 수행하여 확인해 보고자 한다.