• Title/Summary/Keyword: Net-shape

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Three Dimensional Shape Morphing of Triangular Net (삼각망의 3 차원 형상 모핑)

  • Yoo, Dong-Jin
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.1
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    • pp.160-170
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    • 2008
  • Shape morphing is the process of transforming a source shape, through intermediate shapes, into a target shape. Two main problems to be considered in three dimensional shape morphing are vertex correspondence and path interpolation. In this paper, an approach which uses the linear interpolation of the Laplacian coordinates of the source and target meshes is introduced for the determination of more plausible path when two topologically identical shapes are morphed. When two shapes to be morphed are different in shape and topology, a new method which combines shape deformation theory based on Laplacian coordinate and mean value coordinate with distance field theory is proposed for the efficient treatment of vertex correspondence and path interpolation problems. The validity and effectiveness of the suggested method was demonstrated by using it to morph large and complex polygon models including male and female whole body models.

Deep Drawing With Internal Air-Pressing to Increase The Limit Drawing Ratio of Aluminum Sheet

  • Moon, Young-Hoon;Kang, Yong-Kee;Park, Jin-Wook;Gong, Sung-Rak
    • Journal of Mechanical Science and Technology
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    • v.15 no.4
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    • pp.459-464
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    • 2001
  • The effects of internal air-pressing on deep drawability are investigated in this study to increase the deep drawability of aluminum sheet. The conventional deep drawing process is limited to a certain limit drawing ratio(LDR) beyond which failure will occur. The intention of this work is to examine the possibilities of relaxing the above limitation through the deep drawing with internal air-pressing, aiming towards a process with an increased drawing ratio. The idea which may lead to this goal is the use of special punch that can exert high pressure on the internal surface of deforming sheet during the deep drawing process. Over the ranges of conditions investigated for Al-1050, the local strain concentration at punch nose radius area was decreased by internal air-pressing of punch, and the deep drawing with internal air-pressing was proved to be very effective process for obtaining higher LDR.

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The Effect on the Thickness Variation According to Rolling Condition and Temperature Drop At Top-end in Plate Rolling (후판 압연 시 공정변수 및 선단부의 온도저하가 두께편차에 미치는 영향)

  • Yim, H.S.;Joo, B.D.;Lee, H.K.;Seo, J.H.;Moon, Y.H.
    • Journal of the Korean Society for Heat Treatment
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    • v.22 no.1
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    • pp.16-22
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    • 2009
  • The rolling process is an efficient and economical approach for the manufacturing of plate metals. In the rolling process, the temperature variation is very critical for plate thickness accuracy. The main cause of thickness variation in hot plate mills is the non-uniform temperature distribution along the length of the slab. Also the exit plate thickness is mainly affected by the rolling conditions such as mill modulus, plate thickness and plate width. Hence the thickness variation in top-end is also dependent on these factors. Therefore this study has concentrated on determining the correct amounts of thickness variation due to top-end temperature drop and process parameters.

A CAE Approach for Net-Shape Automobile Stamping Components of Aluminum Alloy (자동차용 알루미늄 합금 정형의 스탬핑 부품 성형을 위한 CAE 기법 개발)

  • Choi, Han-Ho;Ku, Tae-Wan;Hwang, Sang-Moon;Kang, Beom-Soo
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.10
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    • pp.164-171
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    • 1999
  • An optimum blank design technology is required for near-net of net-shape cold forming using sheets. Originally, the backward tracing scheme has been developed for preform design in bulk forming, and applied to several forming processes successfully. Its key concept is to trace backward from the final desirable configuration to an intermediate preform of initial blocker. A program for initial blank design in sheet forming which contains the capabilities of forward loading simulation by the finite element method and backward tracing simulation, has been developed and proved the effectiveness by applying to a square cup stamping process. In the blank design of square cup stamping, the backward tracing program can produce an optimum blank configuration which forms a sound net-shape cup product without machining after forming. Another general application appears in the blank design of a cup stamping with protruding flanges, one of typical automobile components. The blank configurations derived by backward tracing simulation have been confirmed by a series of loading simulations. The approach or decision of an initial blank configuration presented in this study will be a milestone in fields of sheet forming process design.

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Model Test on the Opening Efficiency of the Midwater Pair Trawl Net (쌍끌이 중층망의 전개성능에 대한 모형실험)

  • 김정문;김진건
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.36 no.2
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    • pp.73-88
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    • 2000
  • A series of analysis and experiment on the fishing gear and method of the existing midwater pair trawl net with 12,800mm of maximum mesh size is carried out to determine the most effective shape factor. As the first step of this study, the fishing gear and method for the existing net are analyzed to solve problems, such as being low of the net height by increasing the towing speed, twist of net pendant and twine, suspension of float between knots of mesh. etc. Standing on these results, the existing net are modified by very effective shape based on the theory and technology designing the fishing gear. Also, the model experiment is carried out to determine the most effective shape factor of the modified net in the circulation water channel. The obtained results can be summarized as follows : 1. On the length of net pendants(No.2 and No.3) connected with side line, opening efficiency of net with length 8.0cm of net pendant is the greatest and in the order of 11.5cm, 15.0cm. 2. On the number of the net pendant, opening efficiency of net with 4 lines of net pendant is the greatest and in the order of 3 lines, 2 lines. Center part of side panel is pushed out backward, and the pushed length is increasing by increasing flow speed. 3. On the sinking force, opening efficiency of the net is increasing by increasing sinking force. And opening efficiency shows almost the same when sinking force is greater about 1.5 times than that of the existing net in case of the net with 3 lines of net pendant, and about 1.6 ~ 1.7 times than that of the existing net in case of the net with 2 lines.

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A Study on the Shape Finding of Cable-Net Structures Introducing General Inverse Matrix (일반역행열(一般逆行列)을 이용(利用)한 케이블네트 구조물(構造物)의 형상결정에 관한 연구)

  • Sur, Sam-Uel;Lee, Jang-Bok
    • Journal of Korean Association for Spatial Structures
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    • v.2 no.1 s.3
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    • pp.75-84
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    • 2002
  • In this study, the 'force density method' for shape finding of cable net structures is presented. This concept is based on the force-length ratios or force densities which are defined for each branch of the net structures. This method renders a simple linear 'analytical form finding' possible. If the free choice of the force densities is restricted by further condition, the linear method is extended to a nonlinear one. The nonlinear one can be applied to the detailed computation of networks. In this paper, the general inverse matrix is introduced to solve the nonlinear equilibrium equation including Jacobian matrix which is rectangular matrix. Several examples for linear and nonlinear analysis applied additional constraints are presented. It is shown that the force density method is suitable for form finding of cable net and the general inverse matrix can be applied to solve the nonlinear equation without Lagrangian factors.

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Optimum Design of Glass Net in 2[MVA] Mold Transformer (2[MVA] 배전용 몰드변압기의 글라스넷 형상 최적설계)

  • Jeon, Mun-Ho;Kim, Chang-Eob
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.1
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    • pp.107-112
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    • 2011
  • In this paper, the optimum design of the glass net shape was studied to minimize the electric field of mold transformer. The glass net is used for reinforcement in structure between coils and epoxy, but it can cause to increase the electric field and the partial discharge. Therefore, the optimum design of glass net is required to minimize the electric field. In this paper, the objective function was approximated by using response surface method and then Zoom-in method was used for optimal design to minimize the electric field. The electric field was analysed using finite element method for each shape of glass nets.

Schooling Behavior and Estimation of the Fish School in Set Net by Fish Finder (어군탐지기에 의한 정치망내의 어군의 행동과 어군량 추정)

  • 신형일
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.22 no.1
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    • pp.11-18
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    • 1986
  • Schooling behavier to a fishing gear and estimation of the volume of fish school in set net have ~ been studied by making use of such techniques as visual observations, underwater cameras, under- water televison. However, all of these observation techniques are subject to restrictions caused by illumination, underwater visibility, underwater transparent and sea conditions. For the above mentioned reasoa, one of the most effective method by this time become generally known a method using fish finder. In this paper, in order to control the fishing ground of set net effectively and to develope the telemetric fish finder, the experiments for the target strength, underwater shape of fishing gear, schooling behavier and volume of fish school with fish finder were performed at Galgott fishing ground of set net located Keouje Island, 15th-24th July and 18th-20th October in 1985. The results of these experiment showed that a method using fish finder in fishing grOlllld of set net is available for estimating distribution and school size, fish behavier in relation to a fishing gear and underwater shape of fishing gears.

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Studies on the Mackerel Purse Seine Operation in the Sea Area of Cheju Island - 1 . Model Experiment on the Changes of Net Shape in Stagnant Water - (제주도 주변해엽 고등어 포착망의 연구 - 1 . 정수에 있어서 망형 변화에 관한 모형실험 -)

  • 박정식
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.22 no.2
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    • pp.7-15
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    • 1986
  • In order to investigate the performance for the mackerel purse seine of one boat purse seiner using in the sea area of Cheju Island, a model net is made of the scale of 1/400 of its full scale, and model test on the shape of net and the tension of purse line is carried out in the stagnant water channel of the circulating water tank. Designing and testing for the model net are based on the Tauti's law. The obtained results are as follows; 1. The sinking rate of net is maximized the value of 6.40 m/min from 5 to 10 minutes after shooting net, and the mean value is 6.13 m/min. 2. The enclosed area formed with the float line after pursing operation is 76-84% of the area which is formed immediately after the shooting operation. At that time, purse seine is pulled inward the circle of surrounding net about 26.5% of the diameter. 3. In operating, when longitudinal section area of the central part of the net is maximized, the split area of both the wing-ends is 31-32% of the former. 4. When the time for the completing of pursing is 20 minutes, the maximum tension of the purse line is about 10.2 tons.

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