• Title/Summary/Keyword: S-shape

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Running Mode Analysis of Exacvator Upper Frame (ODS를 이용한 굴삭기 상부프레임 진동 해석)

  • 김원영;전범석;박경철
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.10a
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    • pp.358-363
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    • 1997
  • The Operational Deflection Shape designates the motion pattern by which a structure vibrates under a specific operating condition. Modal Analysis is usually tested under test bench, but Operational Deflection Shape can be measured directly under real operating condition. It provide useful information for trouble-shooting and aid understanding and evaluation of the absolute dynamic behaviour of a machine or component. In this paper, It is analysed Excavator Upper Frame using Operating Deflection Shape.

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Intake Performance Characteristics according to S-duct Cross-section Shape in UAV (무인기 S형 흡기구의 단면 형상에 따른 흡기구 성능 특성)

  • Eom, Hee-Ok;Bae, Ji-Yeul;Lee, Namkyu;Kim, Jihyuk;Nam, Juyeong;Jo, Hana;Cho, Hyung Hee
    • Journal of the Korean Society of Propulsion Engineers
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    • v.23 no.5
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    • pp.107-114
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    • 2019
  • In many military aircraft, s-shaped diffusers are used to prevent the fan blades of the turbofan engine from being exposed to the outside. The inlet configurations of the air intakes for military aircraft vary, such as the rectangular intake of the F-22, the crescent-like intake of the F-16, elliptical intake of the MQ-25. In this study, the aerodynamic performance of s-shaped diffusers with various inlet configurations was evaluated using numerical analysis. In addition, the configuration of the middle section of an s-shape duct was changed to the crescent shape, and the effects on its aerodynamic performance were investigated. As a result, there was a slight difference in total pressure recovery according to various inlet configurations with ellipse-shaped middle sections. Also, the total pressure distortion was the lowest in the rectangular inlet shape. When the configuration of the middle section was changed from an ellipse to a crescent shape, the total pressure recovery remained at a high level, except for the ellipse-shaped inlet configuration. In terms of total pressure distortion, the duct with the crescent-shaped middle section showed a significantly more uniform pressure distribution than that with the ellipse-shaped middle section.

The Characteristic of L-shape and Triangular Slot Antenna

  • Narkcharoen, K.;Charkrit, P.;Anantrasirichai, N.;Wakabayashi, T.
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.1680-1683
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    • 2003
  • To describe the performance of an antenna, some parameters are necessary. Some of the parameters are interrelate and not all of them must be specified for complete description of antenna performance. The parameters in characteristics of printed antenna for this analysis are radiation pattern, input impedance, VSWR, S parameter and electromagnetic field. In this paper we will consider two shaped of slot antennas one is triangular slot antenna and other is L - shape slot antenna for compare the radiation pattern, return loss, and VSWR. Two slot antennas are designed to have a resonant frequency at 10 GHz. The microstrip line is designed to be 50 ohms in order to match the measurement system, it has the substrate of the thickness = 1.52 mm and dielectric constant (${\varepsilon}_r$) 2.17. The problem space in the FDTD analysis are $60{\times}123{\times}100$ cells for L-shape slot antenna and $50{\times}171{\times}120$ cells for triangular slot antenna with the cell dimensions ${\Delta}x=0.152\;mm.$, ${\Delta}y={\Delta}z=0.15\;mm.$

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A study on the shape optimization of ship's bellows (선박용 벨로우즈의 형상최적화에 관한 연구)

  • Kim J.P.;Kim H.S.;Kim H.J.;Cho W.S.;Jeh S.B.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1303-1306
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    • 2005
  • The mechanical properties of bellows, such as the extensibility and the strength can be changed depending on the shape. For the shipbuilding material, it is favorable that the fatigue life is long due to the elastic property and the reduction of thermal stress in piping system. Nowadays, the domestic production and design of bellows are based on the E.J.M.A Code. Therefore, the design standard is in need because of much errors and lack of detailed analysis. In this study, it is attempted to find out the optimal shape of U-type bellows using the finite element method. The effective factors, mountain height, length, thickness, and number of mountains and the length of joint are considered and the proper values are chosen for the simulation. The results shows that if the number of mountains are reduced, the volume decreases while the stress increases. However, the number of mountains are increased, the volume increases above the standard volume and the stress obviously increases. In addition, the effect of the thickness of bellows on the stress is very large. Both of the volume and stress are decreasing at a certain lower value region.

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Performance-based comparison of energy pile of various heat exchange pipe arrangement by in-situ thermal response test (현장 열응답 시험을 통한 에너지파일의 열교환파이프 배열 방식에 따른 성능 비교)

  • Min, Sunhong;Koh, Hyungseon;Yoo, Jaihyun;Jung, Kyoungsik;Lee, Youngjin;Choi, Hangseok
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.196.1-196.1
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    • 2011
  • In this study, a test bed was constructed in order to evaluate thermal efficiency of the energy pile which carries out combined roles of a structural foundation and of a heat exchanger. The energy pile in this study is designed as a large-diameter drilled shaft equipped with the heat exchange pipes which configures a W-shape and an S-shape. The drilled shaft reached to the depth of 60 m whilst the heat exchange pipes were installed to about 30 m deep from the ground surface. The W-shaped and S-shaped heat exchange pipes were installed in the opposite sections of the same drilled shaft. In-situ thermal response tests were performed for both the shapes of heat exchange pipes. To avoid underestimating the thermal performance due to hydration heat of concrete inside the drilled shaft, the in-situ thermal response tests for the energy pile were performed after four weeks since the installation of the energy pile.

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An optimal codebook design for multistage gain-shape vector quantizer using genetic algorithms (유전알고리즘에 의한 다단 gain-shape 양자화기의 최적 코드북 설계)

  • 김대진;안선하
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.34S no.1
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    • pp.80-93
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    • 1997
  • This paper proposes a new technique of optimal codebook design in multistage gain-shape vector quantization (MS-GS VQ) for wireless image communication. An original image is divided into a smany blocks as possible in order to get strong robustness to channel transmission errors: the original image is decomposed into a number of subband images, each of which contains a sperate spatial frequency information and is obtained by the biorthogonal wavlet transform; each subband is separated into several consecutive VQ stages, where each stage has a residual information of the previous stage; one vector in each stage is divided into two components-gain and shape. But, this decomposition genrates too many blocks and it thus makes the determination of optimal codebooks difficult. We overcome this difficulty by evolving each block's codebook independently with different genetic algorithm that uses each stage's individual training vectors. Th eimpact of th eproposed VQ technique on the channel transmission errors is compared with that of other VQ techniques. Simulation results show that the proposed VQ technique (MS-GS VQ) with the optimal codebook designe dy genetic algorithms is very robust to channel transmission errors even under the bursty and high BER conditions.

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Numerical Flow Simulations Around High Speed Train Using CHIMERA Grid Technique (CHIMERA 격자기법을 이용한 고속전철 주위의 전산유동해석)

  • Choi S. W.;Kim I. S.
    • Journal of computational fluids engineering
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    • v.1 no.1
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    • pp.81-87
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    • 1996
  • The aerodynamic charateristics of high speed train can be improved by well-designing of its fore-body shape. In this paper, as a way of the design a fore-body shape which has optimal aerodynamic charasteristics, 9 models of fore-body shapes are proposed and the change of aerodynamic charateristics is studied through calculations of flow field around high speed train for each fore-body shape. The flow field around high speed trains are calculated using Thin-Layer Navier-Stokes equation and Chimera grid technique. The application of Chimera grid technique to these flow calculations over high speed train which has ground plane under the train makes grid generation easily. As a computaional algorithm, Pulliam and Chaussee's Diagonal algorithm, the modified form of the Beam and Warming's AF scheme which operates on block-tridiagonal matrices, is selected to reduce computaional time. Introducing hole points flag concept to this Diagonal algorithm. a algorithm for Chimera grid is generated. The variational trends of aerodynamic characteristics are studied from the results of flow calculations around high speed trains for 9 fore-body shapes.

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Theoretical Investigation on the Stress-Strain Relationship for the Porous Shape Memory Alloy (기공을 갖는 형상기억합금의 응력 및 변형률 관계에 대한 이론적 고찰)

  • Lee Jae-Kon;Yum Young-Jin;Choi Sung-Bae
    • Composites Research
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    • v.17 no.6
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    • pp.8-13
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    • 2004
  • A new three-dimensional model fur stress-strain relation of a porous shape memory alloy has been proposed, where Eshelby's equivalent inclusion method with Mori-Tanaka's mean field theory is used. The predicted stress-strain relations by the present model are compared and show good agreements with the experimental results for the Ni-Ti shape memory alloy with porosity of 12%. Unlike linear stress-strain relations during phase transformations by other models from the literature, the present model shows nonlinear stress-strain relation in the vicinity of martensite finish region.

Process Design of Isothermal Forging for Three-Dimensional Ti-6Al-4V Wing-Shape (Ti-6Al-4V 합금 3D 날개형상의 항온단조 공정설계)

  • Yeom J. T.;Park N. K.;Lee Y. H.;Shin T. J.;Hong S. S.;Shim I. O.;Hwang S. M.;Lee C. S.
    • Transactions of Materials Processing
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    • v.14 no.2 s.74
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    • pp.126-132
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    • 2005
  • The isothermal forging design of a Ti-6Al-4V wing shape was performed by 3D FE simulation. The design focuses on near-net shape forming by the single stage. The process variables such as the die design, pre-form shape and size, ram speed and forging temperature were investigated. The main design priorities were to minimize forging loads and to distribute strain uniformly in a given forging condition. The FE simulation results for the final process design were compared with the isothermal forging tests. The instability of deformation was evaluated using a processing map based on the dynamic materials model(DMM), including flow stability criteria. Finally, a modified process design for producing a uniform Ti-6Al-4V wing product without forming defects was suggested.

Characteristic Analysis and Dating Guidance of European High Heeled Shoes Design in the 18th Century (18세기 하이힐 디자인의 특성 및 연대추정에 관한 연구)

  • Kim, Sun-Ah
    • Fashion & Textile Research Journal
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    • v.10 no.2
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    • pp.128-137
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    • 2008
  • The purpose of this study is to investigate the characteristic analysis and to date guidance of European high heeled shoes in 18th century. The research was conducted by stylistic analysis of high heeled shoes from literature review and museums resource. 14 comparative study on shoe objects dating from 1600-1790 in the Museum at F.I.T., New York, Museum of Art, Boston and Metropolitan Museum of Art, New York were selected. The result of this study are as follows: (1) The origin and development of high heeled shoes were accomplished by protection, social status and exaggeration of body, decoration and fashion. (2) According to the comparative study of Museum objects and literature, characteristic analysis of high heeled shoes from 1700-20s, 1730-40s, 1750-60s, 1770-89 and 1890-1900 were accomplished. (3) Significant elements of European women's shoes from 18th century that aid dating are identified as the presence of white rand, shape of tongue, heel shape and height, latchat, toe shape, color and materials.