• Title/Summary/Keyword: thickness optimization

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Study on Optimization of the Vacuum Evaporation Process for OLED (Organic Electro-luminescent Emitting Display) (유기EL 디스플레이의 진공 성막 공정의 최적화에 관한 연구)

  • Lee, Eung-Ki
    • Journal of the Semiconductor & Display Technology
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    • v.7 no.1
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    • pp.35-40
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    • 2008
  • In OLED vacuum evaporation process, the essential requirements include good uniformity of the film thickness over a glass substrate. And, it is commercially significant to improve the consuming efficiency of material of the evaporant which is deposited on the substrate because of high price of organic materials. In this paper, to achieve the better thickness uniformity and the better organic material consuming rate, a process optimization algorithm was developed by understanding vacuum evaporation process parameters that affect the material consuming efficiency and the uniformity of film thickness. Based on the method developed in this study, the vacuum evaporation process of OLED was successfully controlled. The developed method allowed the manufacture of high quality OLED displays with cheaper fabrication cost.

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A Study on Buckling Load Characteristic of Songdo Convention Center with Initial Imperfection and Joint Rigidity (송도 컨벤션 센터의 초기형상불완전 및 절점강성에 따른 좌굴하중 특성에 관한 연구)

  • Moon, Hye-Su;An, Sang-Gil;Shon, Su-Deok;Lee, Dong-Woo;Kim, Seung-Deog
    • Proceeding of KASS Symposium
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    • 2006.05a
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    • pp.191-204
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    • 2006
  • This paper investigate the optimum thickness distribution of plate structure with different essential boundary conditions in the fundamental natural frequency maximization problem. In this study, the fundamental natural frequency is considered as the objective function to be maximized and the initial volume of structures is used as the constraint function. The computer-aided geometric design (CAGD) such as Coon's patch representation is used to represent the thickness distribution of plates. A reliable degenerated shell finite element is adopted calculate the accurate fundamental natural frequency of the plates. Robust optimization algorithms implemented in the optimizer DoT are adopted to search optimum thickness values during the optimization iteration. Finally, the optimum thickness distribution with respect to different boundary condition

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Optimal Design of Two-Span Steel Box Girder Bridges by LRFD (LRFD에 의한 2경간 강박스형교 최적화 설계)

  • 국중식;신영석
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2001.04a
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    • pp.173-180
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    • 2001
  • In this study steel box girders used as main members of a two span continuous steel bridge, are optimally designed by a Load and Resistance Factor Design method(LRFD) using an numerical optimization method. The width, height, web thickness and flange thickness of the main girder are set as design variables, and light weight design is attempted by choosing the cross-sectional area as an object function. We studied the results of steel box girders and compared with those of 1-type girders. The main program is coded with C++ and connected with optimization modul ADS. which is coded with FORTRAN.

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Design Process of Light-weighted Fuel Cell Vehicle Body Frame (경량 연료전지 차체프레임 설계 프로세스)

  • Kim, Ki-Tae;Kang, Sung-Jong
    • Transactions of the Korean Society of Automotive Engineers
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    • v.18 no.6
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    • pp.114-121
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    • 2010
  • This paper presents a design process of light-weighted fuel cell vehicle (FCV) frame to meet design target of natural frequency in early design stage. At first, using validated FE model for the current design, thickness optimization was carried out. Next. optimization process, comprised of beam model size optimization, shell model design and shell model thickness optimization, was investigated for two frame types. In addition, in order to ensure hydrogen tanks safety against rear impact load, structural collapse characteristics was estimated for the rear frame model finally produced from the previous optimization process and, with the target of equal collapse characteristics to the current design model, structural modification with small weight increase was studied through static structural collapse analyses. The same attempt was applied to the front side frame. The results explain that the proposed process enables to design light-weighted frames with high structural performance in early stage.

A Study on the Optimum Thickness Distributions of Plate Structures with Different Essential Boundary Conditions (경계조건에 따른 판 구조물의 최적두께분포에 대한 연구)

  • Lee, Sang-Jin;Kim, Ha-Ryong
    • Journal of Korean Association for Spatial Structures
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    • v.5 no.4 s.18
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    • pp.53-59
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    • 2005
  • This paper provides the results of the investigation on the optimum thickness distribution of plate structures with different essential boundary conditions. In this study, the strain energy to be minimized is considered as the objective function and the initial volume of structures is used as the constraint function. The computer-aided geometric design (CAGD) such as Coon's patch representation is used to represent the thickness distribution of plates. A reliable degenerated shell finite element is adopted to calculate the accurate strain energy level of the plates. Robust optimization algorithms provided in the optimizer DOT are adopted to search the optimum thickness values during the optimization iteration. Finally, the square plate is used to find out the optimum thickness distribution of plates according to different essential boundary condition.

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Study on Optimization of Temperature Jump-Bending Process for Reducing Thickness Attenuation of Large-Diameter Steel Pipe (대구경 곡관 두께감소율 제어를 위한 온도점프 벤딩 공정의 최적화에 관한 연구)

  • Xu, Zhe-Zhu;Kim, Lae-Sung;Jeon, Jeong-Hwan;Liang, Long-Jun;Choi, Hyo-Gyu;Lyu, Sung-Ki
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.14 no.4
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    • pp.21-27
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    • 2015
  • Induction bending is a method that allows the bending of any material that conducts electricity. This technology applies a bending force to a material that has been locally heated by an eddy current induced by a fluctuating electromagnetic field. Induction bending uses an inductor to locally heat steel through induction. This results in a narrow heat band in the shape to be bent. In general, the reduction of thickness attenuation of a large-diameter steel pipe is not allowed to exceed 12.5%. In this paper, in order to meet the standard of thickness attenuation reduction, a non-uniform heating temperature jump-bending process was investigated. As a result, the developed bending technique meets the requirements of thickness attenuation reduction for large-diameter steel pipes.

Optimal Design of a Multi-Layered Plate Structure Under High-Velocity Impact (다중판재의 고속충돌에 관한 최적설계)

  • Yoon, Deok-Hyun;Park, Myung-Soo;Yoo, Jeong-Hoon;Chung, Dong-Teak
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.10
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    • pp.1793-1799
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    • 2003
  • An optimal design of a multi-layered plate structure to endure high-velocity impact has been suggested by using size optimization after numerical simulations. The NET2D, a Lagrangian explicit time-integration finite element code for analyzing high-velocity impact, was used to find the parameters for the optimization. Three different materials such as mild steel, aluminum for a multi-layered plate structure and die steel for the pellet, were assumed. In order to consider the effects of strain rate hardening, strain hardening and thermal softening, Johnson-Cook model and Phenomenological Material Model were used as constitutive models for the simulation. It was carried out with several different gaps and thickness of layers to figure out the trend in terms of those parameters' changes under the constraint, which is against complete penetration. Also, the measuring domain has been shrunk with several elements to reduce the analyzing time. The response surface method based on the design of experiments was used as optimization algorithms. The optimized thickness of each layer in which perforation does not occur has been obtained at a constant velocity and a designated total thickness. The result is quite acceptable satisfying both the minimized deformation energy and the weight criteria. Furthermore, a conceptual idea for topology optimization was suggested for the future work.

Design Enhancements for Automotive Integrated Shell Structures (차량 복합판형부품의 설계개선 기법들)

  • Lee, Hyeong-Il;Seo, Hyeon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.5 s.176
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    • pp.1103-1114
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    • 2000
  • Recent attempt to enhance the safety against collision reshaped the simple shell structures into the integrated complex shell structures. Moreover, due to various regulations continuously tightened for environment protection, weight reduction of automobiles becomes an increasingly important issue. Auto parts lightening is mainly accomplished by more reasonable design, adoption of lighter materials and miniaturization of the auto bodies. Focusing on the locally enhanced design approach among the above three ways, we here attempt to develop a patching optimization method, and also to determine the thicknesses of an integrated shell structure, both bringing a specified amount of stress relaxation. We first select a cross member as a patching optimization model. Based on the finite element stress calculations, we relieve the stress of cross member by patching in two ways-nonuniform thickness patching and optimized uniform thickness patching, the latter of which is more effective in a practical point of view for the preset amount of stress relaxation. Selecting a box type subframe as another finite element analysis model, we then determine the thickness of each part by axiomatic design approach for a preset amount of stress relaxation. The patching methodology and the axiomatic approach adopted in this work can be applied to the other complex shell structures such as center member and lower control arm.

The analysis and optimization of dual armor plate considering EQPS (EQPS를 이용한 복합장갑의 해석 및 최적설계)

  • 박명수;유정훈;정동택
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2004.04a
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    • pp.111-118
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    • 2004
  • For the precise analysis of high velocity impact problem though FEM with element erosive method, the adequate mesh size and critical equivalent plastic strain(EQPS) is chosen prior to the simulation. In this research, it is strongly required from a standpoint that critical EQPS is used to decide whether perforation occurs or not. The optimization of dual armor plate consisting of 4340 steel and 2024 aluminium against a die steel sphere with high-velocity has been suggested using Lagrangian explicit time-integration code, NET2D. The response surface method based on the design of experiment is utilized for the size optimization. The optimized thickness of each layer, in which perforation does not occur, the strength of multi-layer is maximized and total weight is minimized, is obtained at a constant velocity of a pellet with a designated total thickness.

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Modal Characteristic Optimization of Rotating Cantilever Beams via Shape Variation of Cross-section by Multi-stage Spline Function (다단 Spline 곡선에 의한 단면형상 변화를 통한 회전 외팔보의 진동특성 최적화)

  • 조정은;유홍희
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.1
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    • pp.73-79
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    • 2004
  • When structures undergo rotating motion, their modal characteristics often vary significantly. The variations of modal characteristics are determined from their geometric shapes and their rotating angular speed. Since the modal characteristics vary during the operation of the structures, they should be carefully scrutinized. In this paper, rotating cantilever beams are chosen as design targets which need to meet some specific design requirements. The thickness and the width of the rotating beams are assumed as multi-stage spline functions and the stage values for the thickness and the width are used as design variables for the optimization problems.