• Title/Summary/Keyword: Vertical pressure

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A study on the structural behaviors of air-pressurized vertical arch (공기로 지지되는 수직 아치의 구조거동에 관한 연구)

  • 김재열;이장복;권택진
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1998.10a
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    • pp.274-279
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    • 1998
  • The structural behaviors of a arch composed of flexible membrane are investigated. The membrane is considered as thin shell with internal pressure during FEM analysis by using ABAQUS. In the paper, a wind load and uniformly distributed vertical load are considered. As a vertical load, snow loads including applied over all and half of the structure are introduced. The ends of arch are fixed to the ground. Load-Deflections relationship, buckling mode of the structure are presented.

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Pressure Gradient of Supercritical CO2 in Vertical Tobacco Beds in Down Flow Condition (담배 고정층 반응기에서 하부로 흐르는 초임계 CO2의 압력 구배)

  • 이성철
    • Journal of the Korean Society of Tobacco Science
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    • v.18 no.1
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    • pp.92-99
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    • 1996
  • A mathematical model of the pressure gradient of supercritical CO2 in a vertical tobacco bed was developed in this study. In particular, the compaction of the tobacco as a function of temperature and CO2 flow is included in the model. Downflow of CO2 (low condition is described. At velocities in excess of 0.6 cm/sec at 7$0^{\circ}C$, there is a large increase in pressure gradient for beds deeper than about 0.5 m. The proposed model offers a better understanding of operating the process using supercritical CO2.

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Hydrodynamic Behavior Analysis of Vertical-Cylindrical Liquid-Storge Tanks by Mathematically Analytic Method (수학적 해석 방법에 의한 액체저장탱크의 액동압 거동 해석)

  • Park, Jong-Ryul;O, Taek-Yeol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.3
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    • pp.487-496
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    • 2002
  • Hydrodynamic behavior and response of vertical-cylindrical liquid-storage tank is considered. The equation of the liquid motion is shown by Laplace's differential equation with the fluid velocity potential. The solution of the Laplace's differential equation of the liquid motion is expressed with the modified Bessel functions. Only rigid tank is studied. The equivalent masses and heights for the tank contents are presented for engineering design model.

Engineering Applications of Jet Impingement Associated with Vertical Launching System Design

  • Hong, Seung-Kyu;Lee, Kwang-Seop
    • International Journal of Aeronautical and Space Sciences
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    • v.3 no.2
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    • pp.67-75
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    • 2002
  • In the course of missile system design, jet plume impingement is encountered in designing airframe as well as launchers, requiring careful investigation of its effect on the system. In the present paper, recent works on such topic are presented to demonstrate usefulness of CFD results in helping design the hardware. The jet impinging flow structure exhibits such complex nature as shock shell, plate shock and Mach disk depending on the flow parameters. The main parameters are the ratio of the jet pressure to the ambient pressure and the distance between the nozzle and the wall. In the current application, the nozzle contour and the pressure ratio are held fixed, but the jet impinging distance is varied to illuminate the characteristics of the jet plume with the distance. The same methodology is then applied to a complex vertical launcher system (VLS), capturing its flow structure and major design parameter. These applications involving jets are thus hoped to demonstrate the usefulness and value of CFD in designing a complex structure in the real engineering environment.

The Study on permeability enhancement in smear zone using electro-osmotic pressure (전기 삼투압을 이용한 교란영역의 투수성 개선에 관한 연구)

  • Ahn, Byung-Wook;Noh, Hee-Jeon;Kim, Hyun-Ki;Cho, Nam-Jun
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.435-441
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    • 2008
  • More time is required for consolidating soft clay when its hydraulic conductivity around the vertical drains is reduced by soil disturbance. One of the methods to be proposed to solve such problem is the electro-osmotic flow application. This study presents the experimental results of model tests using a modified oedometer and a large-scale cylinder with a sand drain. Results show that the development of negative excessive pore water pressure due to the DC electrical field in saturated clay can be transformed to additional loads causing more consolidation settlement.

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Depositional Characteristics of Busan Clay, Effects of Artesian Pressure, and Experiences from Ground Improvement (부산 점토의 퇴적 특성, 피압의 영향 및 지반 개량에서 얻은 경험)

  • Kim, Sang-Kyu
    • Proceedings of the Korean Geotechical Society Conference
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    • 2007.09a
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    • pp.3-38
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    • 2007
  • The depositional characteristics of Busan clay are initially described in this paper. The deposits of the Nakdong River estuary are composed of some different layers, which have been affected by marine transgression and regression. The upper clay layer is thick and soft. The lower clay layer and some depth of the upper clay layer have been leached by artesian pressure existing in an aquifer below. The clay shows unique physical and engineering characteristics due to leaching. Several large-scale reclamation projects have been performed in this delta area. The preloading method using long vertical drains has been applied for soft ground improvement. Experiences obtained from ground improvement are mentioned in connection with the depositional characteristics of the clay layers.

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The Effects of Vertical Laryngeal Movements on the Vocal Folds (후두 수직운동이 성대에 미치는 영향)

  • Hong, Ki-Hwan;Kim, Hyun-Ki
    • Speech Sciences
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    • v.1
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    • pp.261-274
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    • 1997
  • In spite of the presumed importance of the strap muscles on laryngeal valving and speech production, there is little research concerning the physiological role and the functional differences among the strap muscles. Generally, the strap muscles have been shown to cause a decrease in the fundamental frequency(Fo) of phonation during contraction. In this study, an in vivo canine laryngeal model was used to show the effects of strap muscles on the laryngeal function by measuring the Fo, subglottal pressure, vocal intensity, vocal fold length, cricothyroid distance, and vertical laryngeal movement. Results demonstrated that the contraction of sternohyoid and sternothyroid muscles corresponded to a rise in subglottal pressure, shortened cricothyroid distance, lengthened vocal fold, and raised Fo and vocal intensity. The thyrohyoid muscle corresponded to lowered subglottal pressure, widened cricothyroid distance, shortened vocal fold, and lowered Fo and vocal intensity. It was postulated that the mechanism of altering Fa and other variables after stimulation of the strap muscles is due to the effects of laryngotracheal pulling, upward or downward, and laryngotracheal forward bending, by the external forces during strap muscle contraction.

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Characteristics of Rainfall Protection for Stacks (굴뚝의 우수유입방지 특성)

  • Kim, Jong-Chul;Kim, Tae-Hyeung
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.10 no.1
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    • pp.18-31
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    • 2000
  • A stack must be designed to 1) reduce or eliminate rainfall or snowfall into a industrial exhaust system, 2) minimize a resistance to flow, 3) maximize the vertical dispersion of the contaminated air and 4) minimize maintenance. The weather cone stacks and the elbow-type stacks are very popular in Korea. But they add some resistance to the exhaust system resulting in reduction of air flow rate, but also deflect the noxious contaminants downward in undiluted form. To solve these problems, ACGIH (American Conference of Governmental Industrial Hygienists) suggested the vertical discharge stack with concentric space between the upper stack with larger diameter and the lower stack with smaller diameter. The preliminary test showed that the vertical discharge stacks did not have the good rainfall protection. The reversed cone were newly devised to satisfy the requirements for the good stack. Subsequently, the amount of rain being penetrated through the stacks was measured while the stacks were simultaneously and naturally exposed to rain in the same area outside. Test results indicate that none of the stacks tested completely exclude rain. The efficiency of rainfall protection and the pressure loss coefficient were compared. The temporary conclusion was reached to the point that the reversed cone stack is the best one. Further research is underway.

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Gravitational Instability of Rotating, Vertically-Stratified, Polytropic Disks

  • Kim, Jeong-Gyu;Kim, Woong-Tae;Hong, Seung-Soo
    • The Bulletin of The Korean Astronomical Society
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    • v.36 no.2
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    • pp.111.2-111.2
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    • 2011
  • While many astrophysical disks are vertically stratified and obey a polytropic equation of state, most studies on gravitational instability (GI) of flattened systems consider isothermal, razor-thin disks by taking vertical averages of disk properties. We investigate local GI of rotating pressure-confined polytropic disks with resolved vertical stratification by performing linear stability analysis. We find that the GI of vertically-stratified disks is in general a combination of conventional razor-thin Jeans modes and incompressible modes. The incompressible modes that dominate in the limit of the maximal disk compression require surface distortion and are an unstable version of terrestrial water waves. Disks with a steeper equation of state are found to be more Jeans unstable because they tend to have a smaller vertical scale height as well as a steeper temperature gradient corresponding to lower pressure support. GI depends more sensitively on the vertical temperature than density distribution. The density-weighted, harmonic mean, rather than the simple mean, of the adiabatic sound speed well describes the dispersion relation of horizontal modes, and thus is appropriate in the expression for Toomre Q stability parameter of razor-thin disks. We generalize Q into vertically-stratified disks, and discuss astrophysical application of our work.

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An Experimental Study for Soil Pressure Increment Ratios according to Strip Load in Sandy Soil (사질토 지반의 띠하중 재하에 따른 지중응력증가비의 실험적 고찰)

  • Bong, Tae-Ho;Kim, Seong-Pil;Heo, Joon;Son, Young-Hwan
    • Journal of The Korean Society of Agricultural Engineers
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    • v.53 no.4
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    • pp.21-27
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    • 2011
  • Soil stress distribution under loading is one of the important problems in civil engineering. Many models have been proposed to interpret the stress distribution in soil and most models assume that the soil is homogeneous and isotropic. Therefore, the actual stress distribution may be different. In addition, With the increase of the top load, soil stress does not increase linearly. In this study, vertical stress changes in sandy soil according to top load increase were measured through experiments. Experimental results, vertical soil stress due to top load increase showed an initial nonlinear behavior and when the load increases to some extent, vertical soil stress showed a linear behavior. ${\alpha}$ value obtained by existing theories always 1.00. But, ${\alpha}$ value by experiment was observed from 0.91 to 1.22 and ${\alpha}$ value was increased with increasing distance from the loading plate.