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Investigation of Velocity Boundary Conditions in Counterflow Flames

  • Park, Woe-Chul;Anthony Hamins
    • Journal of Mechanical Science and Technology
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    • v.16 no.2
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    • pp.262-269
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    • 2002
  • The effects of velocity boundary conditions on the structure of methane-air nonpremixed counterflow flames were investigated by two-dimensional numerical simulation. Two low global strain rates, 12 s$\^$-1/ and 20 s$\^$-1/, were considered for comparison with measurements. Buoyancy was conformed to have strong effects on the flame structure at a low global strain rate. It was shown that the location where a top hat velocity profile was imposed is sensitive to the flame structure, and that the computed temperature along the centerline agrees well with the measurements when plug flow was imposed at the inner surface of the screen nearest the duct exit.

Computation of Unsteady Separated Flows Using the Vortex Particle Method (ll) - Stability and Particle Redistribution - (와류입자법에 의한 비정상 박리흐름의 전산 (II) - 안전성과 와류입자 재배열 -)

  • Park, Woe-Chul
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.10
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    • pp.1223-1228
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    • 1999
  • As part of study on separated flow using the vortex particle method, stability of the method and particle redistribution were scrutinized. Stability was investigated by choosing different combination of numerical parameters. The Gaussian vortex was considered to make the problem simple by eliminating the complexity due to presence of walls. It was shown that the numerical method was stable when $v{\Delta}t/h^2{\leq}0.5$. In all the stable cases the circulation and the linear momentum were conserved. Without the particle redistribution, the angular momentum was severely attenuated.

The Literature Study on Medical treatments with acupuncture for "Tennis elbow" (주통의 침구치료(鍼灸治療)에 사용(使用)된 경혈(經穴)에 관한 문헌적(文獻的) 고찰(考察))

  • Ryu, Eun Sang;Lee, Hyun;Lee, Byung Ryul
    • Journal of Haehwa Medicine
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    • v.13 no.1
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    • pp.261-267
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    • 2004
  • As mentioned above, I have acquired some valuable results about medical treatments with acupuncture for "Tennis elbow" after studying oriental medical books. 1. In "HungTiNeiChing", there was called "joo-ryun" and "joo-mang" related to "Tennis elbow". 2. The medriens which remedy for 'tennis elbow' are as follow : 'Soo-yangmyoung', 'Soo-soyang', 'Soo-taeeum', 'Soo-gueleum', 'Chok-taeyang', 'Soo-taeyang' and 'Soo-soeum' in the order of frequency of use. 3. The acupuncture points which remady for 'tennis elbow' are as follow : 'Gok-ji', 'Soo-sam-ri', 'Joo-ryo', 'Hap-gok' and 'Woe-kwan' in the order of frequency of use. 4. Medical treatment with acupuncture is based on occuring area of pain and path of 'Kyoung-Rak'.

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Causes of the Fire at an Indoor Shooting Range in Busan

  • Park, Woe-Chul;Lee, Nae-Woo;Jeong, Lee-Gyu
    • International Journal of Safety
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    • v.9 no.1
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    • pp.1-5
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    • 2010
  • On-site examinations and fire simulation were carried out to speculate on causes of the fire at an indoor shooting range in Busan. An experiment on the ignitability of unburned gunpowder was also conducted. Cigarette was the most likely source of ignition for the fire, while impact of a stray bullet failed to ignite the unburned gunpowder. The explosion in the shooting area was presumed to be caused by violent combustion of the polyurethane foam and unburned gunpowder accumulated on it. Fire safety measures include prohibit of use of profile polyurethane foam, complete clean-up of unburned gunpowder, and removal of steel components from the bullet trap.

Problems And Improvements of the Standards Code for Plant Design (플랜트 설계를 위한 표준코드의 문제점 및 개선방향)

  • Gu, Bon-Hak;Kim, Tae-Hui
    • Proceedings of the Korean Institute Of Construction Engineering and Management
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    • 2006.11a
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    • pp.659-662
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    • 2006
  • Plant industry is very important industry that dominate 70% of standard foreign countries construction acceptance an order woe 2004 years. Technique of plant industry is state that secure part equipment connection detailed design and construction class' competitive power. But, high added value creation among plant industry need technique elevation because available plan, basic design technology is insufficient. Therefore, high added value creation wishes to present problem of standard code and improvement direction for plant design to improve available plan, basic design technology competitive power.

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A Numerical Study of a Room Fire for Fire Sizes II. wall fire and corner fire (FDS를 이용한 실내화재 모사의 문제점 II. 벽면형 및 모서리형 화재)

  • Ko Kyung-Chan;Park Woe-Chul
    • Journal of the Korean Society of Safety
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    • v.19 no.3 s.67
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    • pp.9-13
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    • 2004
  • To confirm the previous finding that FDS predicts a fire growth rate too rapid compared with an experiment in a center fire in a room with an opening, the same computational fluid dynamics was applied to two types of fires, wall fire and comer fire. First the grid size was chosen to eliminate possible numerical errors due to a coarse grid system. Then the two types of fires were simulated for three different fire sizes, 7.65, 21.25, and 51.57kW for each type, which are the same as in the experiment to be compared with. The fires were predicted to grow too fist although the average temperatures and heights of the neutral planes were in good agreement with measurement.

A Scheme on System Establishment of Customs Duties of Import Goods in Global EC (글로벌 전자상거래 관세부과의 제도적 정비 방안)

  • Lee, Je-Hong
    • International Commerce and Information Review
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    • v.6 no.2
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    • pp.243-263
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    • 2004
  • Recently, International electronic commerce has been rapidly increasing. Over the past decade, e-commerce on the business foundation of the Internet compound has entered extensive areas of international trade and social activity. This paper focuses on the system establishment of customs duties of import goods in Global e-Commerce. Today, USA, EU and some major countries, International Organization insisted to Tariff-free woe in customs duty. This study also will discuss the effect of imposition of import duties. In order to impose customs duties, it needs to establish a system scheme, especially, because international payment of BtoC Commerce occur by the Credit Card. This study deals with Customs duties of import goods in Global e-Commerce.

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Investigation of Effects of Duct Thickness an Counterflow Flam Structure (닥트두께가 대향류 화염구조에 미치는 영향의 조사)

  • Park, Woe-Chul;Ko, Kyung-Chan
    • Journal of the Korean Society of Safety
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    • v.17 no.4
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    • pp.61-65
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    • 2002
  • Nonpremixed counterflow flames at low strain rates, $ag=12s^{-1}$ and $12s^{-1}$, were numerically simulated to investigate the effects of the duct thickness on the flame structure in normal gravity. For small values of the duct thickness, the positions of the flame and stagnation point were highly sensitive to the duct thickness. When the duct thickness was greater than 6mm, however, the effects of the duct thickness on the flame structure were negligible. The computed temperature along the duct centerline agreed well with measurements.

A Numerical Study on Smoke Exhaust at a Underground Room Fire (지하실 화재에서 배기의 효과에 관한 수치연구)

  • Ko, Kyung-Chan;Park, Woe-Chul
    • Journal of the Korean Society of Safety
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    • v.20 no.4 s.72
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    • pp.9-13
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    • 2005
  • A underground room fire was simulated to investigate the effects of smoke exhaust on temperature visibility, soot etc. in the room. A room of $6m{\times}6m{\times}2.5m$ with a door of $0.9{\times}2.0m$ and a 0.5MW polystyrene fire in the room were considered. Temperature, visibility, CO volume fraction and soot were compared for the exhaust velocity at a vent located at the ceiling, 0, 1.2, and 2.4m/s, respectively. Results showed that increasing exhaust velocity decreased room temperature, CO and soot and increased visibility.

Numerical Simulation of Vertical Wall fires II. Propane Fire (수직벽화재의 수치 시뮬레이션 II. 프로판 화재)

  • Park, Woe-Chul;Trouve, Arnaud
    • Fire Science and Engineering
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    • v.22 no.3
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    • pp.188-193
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    • 2008
  • Numerical simulation was carried out for a propane fire of mass transfer rate 3g/m^2-s$ on a 1m high vertical wall. The objectives of this study are to confirm the outcomes of evaluation of the simulator through simulation of natural convection, and to compare the results of the wall fire with those of previous studies. It was confirmed that the simulated boundary layer was laminar at C_s=0.2$ while it was turbulent at C_s=0.1$. The z direction velocity showed lack of turbulent mixing as seen in the natural convection case, and the profiles of temperature and velocities were in relatively good agreement with those of experiment and previous simulation. It was found that the air entrainment into the boundary layer was well predicted.