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Flow and Heat Transfer Characteristics in Ice Making Heat Exchanger Applied to Ice-Storage System (빙축열 시스템의 제빙용 열교환기내에서 유동 및 열전달 특성)

  • Back, Young-Ryoul;Lee, Jae-Heon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.6 no.2
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    • pp.110-119
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    • 1994
  • Three dimensional characteristics of fluid flow and heat transfer have been studied numerically around the latent heat storage vessel which was applied to the practical ice-storage system. The result obtained indicates that the value of frictional coefficient decreases with decrease of baffle width. For the baffle spacing. $S/H_D=9.375$, baffle height. $H/H_D=0.5$ and various pressure drop, average Nusselt numbers in heat transfer surface are much dependent on the width of side baffle and middle baffle. that is. Nu_m decreases with decrease of the width of middle baffle when the width of side baffle is 4.375, where as the optimum condition of side baffle for $Nu_m$ exists in the range of 3.5< $B_1/H_D$ <4.375 at the width of middle baffle, $B_2/H_D=6.875$.

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Physicochemical factors affecting the adsorption of E. coli in estuarine sediments (하구퇴적토 환경에서 E.coli의 부착에 영향을 주는 물리화학적 요인)

  • 이건형
    • Korean Journal of Microbiology
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    • v.26 no.3
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    • pp.237-246
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    • 1988
  • The higher bacterial numbers on clay than on sand were caused by different environmental factors. Such factors affecting the adsorption of E. coli ATCC 11775 in the sediment as follows; optimal pH range for the adsorption of E. coli ATCC 11775 was pH 7.5-pH 9.5. E. coli ATCC 11775 were shown maxima in the salinity of 18.$75%_{o}$ on sand type sediment and $12.5%_{o}$ on clay type sediment. Bacteria attached better to clay typed sediment than to sand typed sediment when organic substance was eliminated. Beef extract of 0.5%-1% concentration was found to promote the attachment of E. coli ATCC 11775 effectively. Peptone of 0.5% was enganced the attachment on the clay, and peptone of 1.3%-5%, on the sand. E. coli ATCC 11775 was found to adsorb onto benthonite with the highest efficiency and on celite with the lowest efficiency. Efficiency of adsorption by inorganic ions was shown due to higher values of ion. Adsorption was achieved in the order of $Al^{3+}, Ca^{2+}, Na^{+}$.

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Natural Dyeing of Silk Fabrics with Rumex crispus L. Root (소루쟁이뿌리를 이용한 견직물의 천연염색)

  • Han, Mi-Ran;Lee, Jeong-Sook
    • Fashion & Textile Research Journal
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    • v.11 no.1
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    • pp.166-173
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    • 2009
  • The natural dyeing of silk fabrics with Rumex crispus L. root extract was investigated. The dyeability of Rumex crispus L. root extract was evaluated with condition of concentration, temperature, time, repeat-numbers, pH, mordants variables, methods of mordanting, color fastness and antibacterial activity, etc. The wavelength of maximum absorption of the Rumex crispus L. distilled water extract appears at 274 nm and 336 nm, methanol extract was 274 nm and 356 nm. Optical dyeing temperature of silk fabrics was $70^{\circ}C$. The K/S values of the dyed fabrics were increased with increasing dyeing time. Surface colors of dyed fabrics were various by the used mordants; RP-YR-Y range. The color fastness was improved by adding mordants were added except Sn. Dyed silk fabrics with mordants showed antibacterial activity.

The Latest Achievements in Study of Tuberculosis (결핵 연구의 최근 성과들)

  • Yim, Jae-Joon
    • Tuberculosis and Respiratory Diseases
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    • v.71 no.6
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    • pp.395-399
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    • 2011
  • Tuberculosis is one of the leading causes of mortality and morbidity worldwide. In 2010, there were 8.8 million (range, 8.5~9.2 million) incident cases of TB, 1.1 million deaths from TB among HIV-negative people and an additional 0.35 million deaths from HIV-associated TB. Due to such health-related importance, tuberculosis is one of areas being actively researched. Many numbers of tuberculosis-related papers are being presented each year, and in this review, it summarizes contents of a few papers that had been selected among the papers presented from 2009 to early 2011.

The Study of Suit Design and Materials for Middle-aged Men′s Visual Effect (중년남성 시각효과를 위한 수트디자인과 소재연구)

  • 박순천
    • Korean Journal of Human Ecology
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    • v.4 no.2
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    • pp.123-140
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    • 2001
  • The purpose of this study is to find the suitable suit design of mid-aged men by examining visual effects in Physical and Psychological side aspects. I used convenience sampling by considering sex and age distribution. These methods were used to analyze data that were frequency analysis, variate analysis, centesimal scale, primary factor analysis, three primary variate analysis, duality variate analysis, equation variate analysis and Cronbach's multiplex range verification 1. Image perception of men's suit was analyzed with arrangement, numbers of button, pattern and the shape of one's body and was divided into charming, youthfulness, modernism. affection and manly. 2. 1) There are partly resemblance difference in physical visual effect by the shape of body and suit design. 2) There are partly resemblance differences in psychological visual effect by one's shape and suit design. In conclusion arrangement, number of button and Pattern are very important to give an effect on whole visual effect man's suit. Also, these were felt differently in each types of body Therefore it is confirmed that the type of body is important fluent to make people perceive.

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SPH Parameters for Analysis of Penetration Phenomenon at Hypervelocity Impact of Meteorite (운석의 초고속 충돌 관통현상 해석을 위한 SPH 매개변수)

  • Lee, Sung-Soo;Seo, Song-Won;Min, Oak-Key
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.10
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    • pp.1738-1747
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    • 2003
  • Smoothed Particle Hydrodynamics (SPH), a pure Lagrangian numerical method, is applied to analysis of penetration phenomenon of bumper plate which is installed outside of spacecraft hull to protect the spacecraft against hypervelocity meteorite impact. Effects of SPH parameters, such as artificial viscosities, smoothing lengths, numbers of particles and time increments, are analysed by comparing the SPH simulation results with experimental ones with regard to subsequent formation of debris cloud. An optimum range of parameter values is determined by error analysis and various SPH numerical results are compared with experiments.

Flow Field Analysis of Smoke in a Rectangular Tunnel

  • Lee, Yong-Ho;Park, Sang-Kyoo
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.5
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    • pp.679-685
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    • 2009
  • In order to simulate a smoke or poisonous gas emergency in a rectangular tunnel and to investigate a better way to exhaust the smoke, the characteristics of smoke flow have been analyzed using flow field data acquired by Particle Image Velocimetry(PIV). Olive oil has been used as tracer particles with the kinematic viscosity of air, $1.51{\times}10^{-5}\;m^2/s$. The investigation has done in the range of Reynolds number of 1600 to 5333 due to the inlet velocities of 0.3 m/s to 1 m/s respectively. The average velocity vector and instantaneous kinematic energy fields with respect to the three different Reynolds numbers are comparatively discussed by the Flow Manager. In general, the smoke flow becomes more disorderly and turbulent with the increase of Reynolds number. Kinematic energy in the measured region increases with the increase of Reynolds number while decreasing at the leeward direction about the outlet region.

Effects of near-fault records characteristics on seismic performance of eccentrically braced frames

  • Eskandari, Reyhaneh;Vafaei, Davoud
    • Structural Engineering and Mechanics
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    • v.56 no.5
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    • pp.855-870
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    • 2015
  • In this paper the effects of fling-step and forward-directivity on the seismic performance of steel eccentrically braced frames (EBFs) are addressed. Four EBFs with various numbers of stories (4-, 8-, 12- and 15-story) were designed for an area with high seismic hazard. Fourteen near-fault ground motions including seven with forward-directivity and seven with fling-step effects are selected to carry out nonlinear time history (NTH) analyses of the frames. Furthermore, seven more far-field records were selected for comparison. Findings from the study reveal that the median maximum links rotation of the frames subjected to three set of ground motions are in acceptable range and the links completely satisfy the requirement stated in FEMA 356 for LS performance level. The arrival of the velocity pulse in a near-fault record causes few significant plastic deformations, while many reversed inelastic cycles result in low-cycle fatigue damage in far-fault records. Near-fault records in some cases are more destructive and the results of these records are so dispersed, especially the records having fling-step effects.

The cavitating flow simulation in cryogenic fluid around 3D objects

  • Thai, Quangnha;Lee, Chang-Jin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.05a
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    • pp.264-267
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    • 2010
  • This research focuses on the development of numerical code to deal with compressible two phase flow around three dimensional objects combined with cavitation model suggested by Weishyy et al. with k-e turbulent model. The cryogenic cavitation is carried out by considering the thermodynamic effect on physical properties of cryogenic fluids in physical point of view and implementing the temperature sensitivity in the energy equation of the government equations in numerical point of view, respectively. The formulation has been extensively validated for both liquid nitrogen and liquid hydrogen by simulating the experiments of Hord on hydrofoils. Then, simulations of cavitating turbopump inducers at their design flow rate are presented. Results over a broad range of Nss numbers extending from single-phase flow conditions through the critical head break down point are discussed. In particular, thermal depression effects arising from cavitation in cryogenic fluids are identified and their impact on the suction performance of the inducer quantified.

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The Study of Criteria Weight for Taiwan National Quality Award by Fuzzy Hierarchical Analysis

  • Li, Shao-Chang;Fu, Hsin-Pin
    • International Journal of Quality Innovation
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    • v.7 no.2
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    • pp.83-96
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    • 2006
  • In this paper, fuzzy hierarchical analysis (FHA) is used to explore the process by which the criteria weights of the Taiwan National Quality Award (TNQA) are assigned by TNQA committee members. Each member is allowed to employ fuzzy scales in place of exact scales. Each pairwise comparison of criteria is made through a questionnaire from each TNQA committee member. The membership function of trapezoidal fuzzy numbers is introduced to specify TNQA committee members' intentions. After FHA, the reasonable range of each criterion weight of TNQA is determined. The current criteria weights of TNQA are properly verified.