• Title/Summary/Keyword: shape comparison

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The Study of Performance Comparison on the Inlet Shapes of Fan for Engine Room of Ship Using CFD (CFD를 이용한 선박 기관실 공기 공급용 팬 입구 형상에 따른 성능 비교 연구)

  • Kwon, Do-Hoon;Hong, Youn-Gyun;Koo, Seong-Woo;Jeong, Eun-Soo
    • Special Issue of the Society of Naval Architects of Korea
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    • 2011.09a
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    • pp.25-31
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    • 2011
  • The performance of fan for engine room of ship is absolutely important when it take into consideration work efficiency, work condition, and the performance of various equipments. Fan performance test should be carried out during sea trial to satisfy owner's requirement as above mentioned. We have considered various values to affect fan test result. In here, various values are to be silencer, fan inlet shape, and arrangement of fan room. In general, the shapes of fan inlet is overall circular type because of the shapes of axial fan. So, all vessels built at SHI have been applied fan inlet of circular type. And now, in order to reduce sound of noise from supply fan, big silencer often has been installed at high value vessels. In this case, the capacity of supplied air can be insufficient due to silencer which is an obstructer about air flow. In this paper, we have studied the performance of fan through comparison between a circular shape and a square shape of fan inlet. We also compare with CFD results and experimental results.

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Blast Overpressure Evaluation for Blast Valves in Protective Tunnels with Rectangular-Shaped Tunnel Entrances (각형 출입구를 갖는 방호터널의 방폭밸브에 미치는 폭압 평가)

  • Pang, Seungki;Shin, Jinwon
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.17 no.4
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    • pp.79-90
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    • 2021
  • This paper presents a study to reduce the effect of blast pressure on the blast valves installed in protection tunnels, where the shape of the tunnel entrance and the blast pocket is optimized based on the predetermined basic shape of the protective tunnels. The reliability of the numerical tunnel models was examined by performing analyses of mesh convergence and overpressure stability and with comparison to the data in blast-load design charts in UFC 3-340-02 (DoD, 2008). An optimal mesh size and a stabilized distance of overpressure were proposed, and the numerical results were validated based on the UFC data. A parametric study to reduce the blast overpressures in tunnel was conducted using the validated numerical model. Analysis was performed applying 1) the entrance slope of 90, 75, 60, and 45 degrees, 2) two blast pockets with the depth 0.5, 1.0, and 1.5 times the tunnel width, 3) the three types of curved back walls of the blast pockets, and 4) two types of the upper and lower surfaces of the blast pockets to the reference tunnel model. An optimal solution by combining the analysis results of the tunnel entrance shape, the depth of the blast pockets, and the upper and lower parts of the blast pockets was provided in comparison to the reference tunnel model. The blast overpressures using the proposed tunnel shape have been reduced effectively.

Comparison of Performance of Flexible Solar Cells construction applied to Curtain Walls (커튼 월에 적용하는 플랙시블 태양전지의 모양에 따른 성능 비교)

  • Kim, Jaejin
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.14 no.4
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    • pp.163-168
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    • 2018
  • In this paper presents comparison of performance of flexible solar cells construction applied to curtain walls. The proposed paper compares power generation for curtain walls of various shapes using flexible PV. Through the comparison of performance, the power generation was compared by installing various types of flexible PV on the air layer of double windows. By comparing the measured power generation, it is possible to find an optimal flexible PV shape that can be applied to a curtain wall. Flexible PV installation was divided into diagonal, S and W shapes. As a result of comparison, the amount of power generation when there was no flexure of flexible PV was large. Also, as the angle with the light source increased, the power generation decreased. Therefore, it is necessary to study the structure which can fix the PV more than the flexible PV and to be able to direct the sun without distortion.

Effects of Melt Super-heating on the Shape Modification of ${\beta}-AlFeSi$ Intermetallic compound in AC2B Aluminum Alloy (AC2B 알루미늄합금의 고온용해에 의한 금속간화합물 ${\beta}-AlFeSi$상 형상계량 효과)

  • Kim, Heon-Joo
    • Journal of Korea Foundry Society
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    • v.21 no.3
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    • pp.179-186
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    • 2001
  • Melt super-heating which promotes shape modification of ${\beta}$ intermetallic compounds was conducted to improve mechanical properties of recycled AC2B aluminum alloy. Modification of needle-shape ${\beta}$ intermetallic compounds was effective for the specimens of AC2B aluminum alloys containing 0.85wt.% Fe by melt super-heating, in which the melts had been held at $850^{\circ}C$ or $950^{\circ}C$ for 30 minutes respectively. Owing to the modification of needle-shape of ${\beta}$ intermetallic compounds by melt superheating of the alloy with containing 0.85wt.% Fe to $950^{\circ}C$, increases in elongation and tensile strength were prominent to be more than double and 55% respectively in comparison with the melt heated to $740^{\circ}C$. Moreover, modification of needle-shape ${\beta}$ intermetallic compounds in the alloy containing O.85wt.% Fe by $950^{\circ}C$ melt super-heating led to 48% improvement of the value of impact absorbed energy as compared with the melt heated to $740^{\circ}C$.

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The Study on Thermal Characteristics in Micro Plated Heat Exchangers with Channel Shapes (채널 형상에 따른 마이크로 판형열교환기의 열적 특성 연구)

  • Kim, Yoon-Ho;Seo, Jang-Won;Moon, Chung-Eun;Lee, Kyu-Jung
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.1894-1899
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    • 2007
  • This paper presents the thermal characteristics for micro heat exchanger with different micro-channel shapes. The shapes of micro-channel has been manufactured sheet metal by chemical etching for the I shape of straight channel and V and W shapes of chevron feature and fabricated micro plated heat exchangers using the vacuum brazing of bonding technology. The experimental study has been performed on heat transfer and pressure drop characteristics with various Reynolds number for water to water at the counter flows. The average heat transfer rate of V and W shapes has been showed about 1.5${\sim}$1.6 times large than those of I shape. For the comparison of Nusselt number, it is known that the convective heat transfer of V and W shapes represent more effect than I shape. The pressure drops of V and W shapes are about 1.2${\sim}$1.7 times lager than those of I shape.

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Comparative Study on the Satisfaction with and Perception about Their Bodies by Korean and American Female Students (신체에 대한 의식과 만족도에 대한 한국과 미국여대생의 비교연구)

  • 박우미
    • Journal of the Korean Society of Clothing and Textiles
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    • v.24 no.5
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    • pp.736-747
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    • 2000
  • This study focused on the comparison of satisfaction with and perception about their bodies by Korean and American women. The respondents included 242 Korean and 145 American female student volunteers, aged 18 to 27, who were enrolled at Kwangju and Catholic University and Cornell University in the United States. The questionnaire was composed of three sections; a body cathexis, perceived body shape-self, perceived body shape-ideal. Twenty items of 30 items showed a significant difference between Korean and American women. Korean student females were more dissatisfied with 20 items than American women. Even though Korean women were smaller in body build than the American women, the Korean women were more negative about their large type, shoulder, hands, arms, hips, neck, face, and skin color than the American women. There were many significant differences between perceived body shape-self and perceived body shape-ideal responses for Korean and American respondents. The exceptions were that a fuller bosom, and longer legs than perceived body shape were desired in both cultures, longer arms were desired by Korean women and darker skin color was desired by American women.

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Shape Design Optimization of Fluid-Structure Interaction Problems (유체-구조 연성 문제의 형상 최적설계)

  • Ha, Yoon-Do;Kim, Min-Geun;Cho, Hyun-Gyu;Cho, Seon-Ho
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.2 s.152
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    • pp.130-138
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    • 2007
  • A coupled variational equation for fluid-structure interaction (FSI) problems is derived from a steady state Navier-Stokes equation for incompressible Newtonian fluid and an equilibrium equation for geometrically nonlinear structures. For a fully coupled FSI formulation, between fluid and structures, a traction continuity condition is considered at interfaces where a no-slip condition is imposed. Under total Lagrange formulation in the structural domain, finite rotations are well described by using the second Piola-Kirchhoff stress and Green-Lagrange strain tensors. An adjoint shape design sensitivity analysis (DSA) method based on material derivative approach is applied to the FSI problem to develop a shape design optimization method. Demonstrating some numerical examples, the accuracy and efficiency of the developed DSA method is verified in comparison with finite difference sensitivity. Also, for the FSI problems, a shape design optimization is performed to obtain a maximal stiffness structure satisfying an allowable volume constraint.

A Study on the Characteristics of Software Reliability Model Using Exponential-Exponential Life Distribution (수명분포가 지수화-지수분포를 따르는 소프트웨어 신뢰모형 특성에 관한 연구)

  • Kim, Hee Cheul;Moon, Song Chul
    • Journal of Information Technology Applications and Management
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    • v.27 no.3
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    • pp.69-75
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    • 2020
  • In this paper, we applied the shape parameters of the exponentialized exponential life distribution widely used in the field of software reliability, and compared the reliability properties of the software using the non-homogeneous Poisson process in finite failure. In addition, the average value function is also a non-decreasing form. In the case of the larger the shape parameter, the smaller the estimated error in predicting the predicted value in comparison with the true value, so it can be regarded as an efficient model in terms of relative accuracy. Also, in the larger the shape parameter, the larger the estimated value of the coefficient of determination, which can be regarded as an efficient model in terms of suitability. So. the larger the shape parameter model can be regarded as an efficient model in terms of goodness-of-fit. In the form of the reliability function, it gradually appears as a non-increasing pattern and the higher the shape parameter, the lower it is as the mission time elapses. Through this study, software operators can use the pattern of mean square error, mean value, and hazard function as a basic guideline for exploring software failures.

Numerical Evaluation and Shape Design of Coronary Artery Stent (관상동맥혈관용 스텐트의 수치해석 및 형상 설계)

  • Kim, Dae-Young;Lee, Seung-Yeol;Kim, Heon-Young
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.1
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    • pp.103-108
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    • 2012
  • Restenosis symptom, which is well known as a problem of stents, is due to the recoil and expansion pressure depending on shapes of stent. In order to reduce the effect of recoil problem, study on pattern and shape for the stent is required and the expansion pressure and recoil should be evaluated. This paper aims at evaluating mechanical characteristics of stent used in surgery for vessel stenosis. The expansion process of coronary artery stent in vessel for two models including the Cypher$^{(R)}$ from Johnson & Johnson$^{TM}$ and a suggested model were simulated using the Finite Element Analysis. Comparison of the directional recoil simulation results was made. The issues in the deformed shape of vessel and recoil of Cypher$^{(R)}$ were partially resolved in the suggested model. Therefore, the shape design suggested in this paper was able to reduce the restenosis symptom.

Rapid Manufacturing of 3D Prototype from 3D scan data using VLM-ST (단속형 가변적층쾌속조형공정을 이용한 3차원 스캔데이터로부터 3차원 시작품의 쾌속 제작)

  • 이상호;안동규;김효찬;양동열;박두섭;채희창
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.536-539
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    • 2002
  • The reverse engineering (RE) technology can quickly generate 3D point cloud data of an object by capturing the surface of a model using a 3D scanner. In the rapid prototyping (RP) technology, prototypes are rapidly produced from 3D CAD models in a layer-by-layer additive basis. In this paper, a physical human head shape is duplicated using a new RP process, the Transfer-type Variable Lamination Manufacturing process using expandable polystyrene foam sheet (VLM-ST), after the point cloud data of a human head shape measured from 3D SNX scanner are converted to STL file. From the duplicated human head shape, it has been shown that the VLM-ST process in connection with the 3D scanner is a fast and efficient process in that shapes with free surface, such as the human head shape, can be duplicated with ease. Considering the measurement time and the shape duplication time, the use of 3D SNX scanner and the VLM-ST process is expected to reduce the lead-time fur the development of new products in comparison with the other existing RE-RP connected manufacturing systems.

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