• Title/Summary/Keyword: optimal shape

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OPTIMAL SHAPE DESIGN OF ELECTROSTATIC DEVICES USING DESIGN SENSITIVITY ANALYSIS (설계민감도 해석을 이용한 정전소자의 형상최적화)

  • Koh, Chang-Seop;Jung, Hyun-Kyo;Hahn, Song-Yop
    • Proceedings of the KIEE Conference
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    • 1991.07a
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    • pp.93-96
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    • 1991
  • This paper describes a new algorithm based on design sensitivity analysis for optimal shape design of electrostatic devices. The design sensitivity, the variation of the object function with respect to the design variables, is derived by using implicit differentiation and direct boundary element methods. The proposed algorithm is applied to the optimal shape design of a concentric cable and the rod electrode enclosed by earthed case, It is shown, from the numerical results, that the algorithm is very usefull for the optimal shape design of the electrostatic devices.

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The Selection of the Optimal Gator Wavelet Shape Factor Using the Shannon Entropy Concept (Shannon 엔트로피 개념을 이용한 가보 웨이블렛 최적 형상의 선정)

  • Hong, Jin-Chul;Kim, Yoon-Young
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.176-181
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    • 2002
  • The continuous Gabor wavelet transform (GWT) has been utilized as a useful time-frequency analysis tool to identify the rapidly-varying characteristics of some wave signals. In the application of GWT, it is important to select the Gabor wavelet with the optimal shape factor by which the time-frequency distribution of a signal can be accurately estimated. To find the signal-dependent optimal Gabor wavelet shape factor, the notion of the Shannon entropy which mesures the extent of signal energy concentration in the time-frequency plane is employed. To verify the validity of the present entropy-based scheme, we have applied it to the time-frequency analysis of a set of elastic bending wave signals generated by an impact in a solid cylinder.

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Optimal Design of the Punch Shape for a Housing Lower (펀치 형상에 따른 Housing Lower 최적 공정 설계)

  • Park, S.J.;Park, M.C.;Kim, D.H.
    • Transactions of Materials Processing
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    • v.24 no.5
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    • pp.332-339
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    • 2015
  • In the current paper, a cold forging sequence was developed to manufacture a precisely cold forged H/Lower, which is used as the air back unit in commercial automobiles. The preform shape of the H/Lower influences the dimensional accuracy and stiffness of the final product. The shape factor (SF) ratio and shape of the tools are considered as the design parameters to achieve adequate backward extrusion height and maintain appropriate thickness variations. The optimal conditions of the design parameters were determined by using an artificial neural network (ANN). To experimentally verify the optimal preform and tool shapes, the experiments of the backward extrusion of the H/Lower were executed. The process design methodology proposed in the current paper, can provide a more systematic and economically feasible means for designing the preform and tool shapes for cold forging.

The Selection of the Optimal Gabor Wavelet Shape Factor Using the Shannon Entropy Concept (Shannon 엔트로피 개념을 이용한 가보 웨이블렛 최적 형상의 선정)

  • Hong, Jin-Chul;Kim, Yoon-Young
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11a
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    • pp.324.1-324
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    • 2002
  • The continuous Gabor wavelet transform (GWT) has been utilized as a useful time-frequency analysis tool to identify the rapidly-varying characteristics of some wave signals. In the application of GWT, it is important to select the Gabor wavelet with the optimal shape factor by which the time-frequency distribution of a signal can be accurately estimated. To find the signal-dependent optimal Gator wavelet shape factor, the notion of the Shannon entropy which measures the extent of signal energy concentration in the time-frequency plane is employed. (omitted)

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Optimal Shape of Fillet for Minimum Stress (최소 응력을 갖는 필렛의 형상설계)

  • Kim, Ho-Ryong;Lee, Jang-Yong
    • Journal of the Korean Society for Precision Engineering
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    • v.7 no.4
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    • pp.149-161
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    • 1990
  • In this study, an optimal shape design was performed on a fillet model which is subject to surface traction through minimizing the maximum stress of the fillet. A 2-dimensional quadratic isoparametirc element with 8 nodes was used in stress analysis for finite element method, and Hooke-Jeeves direct search algorithm was adopted for optimi- zation. From the resulting optimal shape, it was found that the maxium von Mises stress on the boundary of fillet was reduced by 36%, compared to other paper in which the cross sectional area of fillet was minimized. In conclusion, a real optimal fillet shape could be obtained in the viewpoint of yielding, and more pratical fillet design could be accomplished.

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A Study On The Stator Slot Shape Design of BLDC Motor (BLDC 모터 고정자 슬롯 형상설계에 관한 연구)

  • Han, Sang-Rog;Lee, Kang-Yeon;Jeong, Byeong-Ho
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.5
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    • pp.41-49
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    • 2015
  • In this paper, we studied an optimal design and efficiency improvement of the BLCD motor used in home electronic appliance. The number of stator slots is chosen depending on the rotor poles, phase number, and the winding configuration. In general, a fractional slots/pole design is preferred to minimize cogging torque. To reduce the winding resistance, we reduced the coil length and we improved the coil space factor. We proposed three types of stator slot shape design for the optimal BLDC motor design. One of them, U-type slot shape is a best optimal design, it proved by the simulated and tested. Optimal design of essential parameters aiming at high winding factor are presented to create for a high-quality system implementation. Design analysis is verified by testing and building a prototype motor.

Optimal design of shape of a working in cracked rock mass

  • Mirsalimov, Vagif M.
    • Geomechanics and Engineering
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    • v.24 no.3
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    • pp.227-235
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    • 2021
  • A criterion and a method for solving a problem on the prevention of mine working fracture under the action of tectonic and gravitational forces are offered. Based on minimal criterion, theoretical analysis of the definition of the optimal shape of working in the rock mass weakened by arbitrarily located rectilinear cracks was carried out. A closed system of algebraic equations allowing to minimize the stress state and stress intensity factors depending on mechanical and geometrical characteristics of the rock, is constructed. The relation between the shape of the working and the stress intensity factors and also location and sizes of the cracks is obtained. The found optimal shape of working increases load-bearing capacity of the rock.

The Effect of Plunger Tip Shape on the Formability in Semi-Solid Die Casting Process (반용융 다이캐스팅 공정에 있어서 플런저 팁의 형상이 성형성에 미치는 영향)

  • 서판기;손영익;강충길
    • Transactions of Materials Processing
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    • v.11 no.4
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    • pp.312-322
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    • 2002
  • In this study, an innovative semi-solid die casting technology to replace heavier cast iron compressor parts with lightweight aluminum castings was proposed, and the application possibility for home-appliance component was investigated. The most important factors regarding the semi-solid die casting process are the reheating process of the raw materials to the semi-solid state, specifications of the forming machine, the optimal injection conditions and die design. Materials used in this study were A3S7 and hSn alloys fabricated by the electromagnetic stirring process. The optimal injection conditions for semi-solid die casting process were Presented with the reheating conditions of the semi-solid materials. To investigate the effect of plunger tip shape on the formability and mechanical properties in semi-solid die casting process for complicated shape part, two kinds of plunger tip shape with long and short plunger tip taper are proposed.

A Study on Shape Design of NFR Suspension for Optimal Dynamic Characteristics (NFR 서스펜션의 동특성을 고려한 형상설계에 관한 연구)

  • Eun, Gil-Soo;Kim, Noh-Yu
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.771-776
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    • 2002
  • Optimal shape of the NFR suspension is studied and developed to improve the dynamic performance and reduce the vibration of the suspension system including a optical head slider. Since accurate position control and stability of the slider motion are highly required in NFR due to the narrower track width and the heavier slider than HDD slider with the low flying height, the dynamic characteristics of the suspension are very important to the mechanical performance of the system. The first natural frequencies in flexural and lateral motion of the suspension are critical factors affecting the dynamics and stability of the flying head, so that the dynamic parameters should be designed properly to avoid an excessive vibration or a crash of the slider on the disk. This paper optimizes the shape of the suspension based on homogenization method in NASTRAN and develops a new suspension shape for NFR system. The suspension is tested on experiment to verify the improvement of the dynamic characteristics.

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Shape Optimization of Cut-Off in Multiblade Fan/Scroll System Using CFD and Neural Network (신경망 기법을 이용한 다익 홴/스크롤 시스템의 컷오프 최적화)

  • Han, S.Y.;Maeng, J.S.;Yoo, D.H.
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.365-370
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    • 2001
  • In order to minimize unstable flow occurred at a multiblade fan/scroll system, optimal angle and shape of cut-off was determined by using two-dimensional turbulent fluid field analyses and neural network. The results of CFD analyses were used for learning as data of input and output of neural network. After learning neural network optimization process was accomplished for design variables, the angle and the shape of cut-off, in the design domain. As a result of optimization, the optimal angle and shape were obtained as 71 and 0.092 times the outer diameter of impeller, respectively, which are very similar values to previous studies. Finally, it was verified that the fluid field is very stable for optimal angle and shape of cut-off by two-dimensional CFD analysis.

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