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A Study on the Calculation of Critical Velocity by Fire Intensity (화재강도에 따른 임계풍속산정에 관한 연구)

  • Kim, Jong-Yoon;Lim, Kyung-Bum;Seo, Tae-Beom;Rie, Dong-Ho;Yoo, Ji-Oh
    • Fire Science and Engineering
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    • v.20 no.4
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    • pp.91-97
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    • 2006
  • This study was executed to review feasibility on the calculation of critical velocity with a reduced model of an actual tunnel in order to establish the optimum fire protection system for a fire in road tunnels. In a scaled model about 1/29 of an actual tunnel based on the Froude scaling, critical velocity was calculated by visualizing smoke flow and analyzing correlation with temperature. In the experiment, critical velocities at which smoke backflow length became zero showed a small difference within about 5% compared to results calculated by the Kennedy formula, and the relation between smoke flow and temperature distribution appeared similarly without getting greatly influenced by changes in fire intensity.

Flow and smoke behavior of a longitudinal ventilation tunnel with various velocities using computational fluid dynamics (팬의 운전조건에 따른 종류식환기터널 내의 연기거동에 관한 전산유체역학연구)

  • Lee, J.H.;Kwon, Y.J.;Kim, D.E.
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.16 no.1
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    • pp.105-115
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    • 2014
  • A numerical analysis on the smoke behavior and evacuee safety has been performed with computational fluid dynamics. The purpose of this study is to build computational processes for an evacuation and prevention of a fire disaster of a 3 km-length tunnel in Korea. To save computational cost, 1.5 km of the tunnel that can include a few cross-passing tunnels is considered. We are going to assess the fire safety in a road tunnel according to the smoke level, which consists of the smoke density and the height from the floor. The smoke density is obtained in detail from three-dimensional unsteady CFD analysis. To obtain proper temperature distributions on the tunnel wall, one-dimensional conduction equation is considered instead of an adiabatic wall boundary or a constant heat flux. The tunnel considered in this study equips the cross passing tunnels for evacuees every 250 m. The distance is critical in both safety and economy. The more cross passing tunnels, the more safe but the more expensive. Three different jet fan operations can be considered in this study; under- and over-critical velocities for normal traffic condition and 0-velocoty operation for the traffic congestion. The SE (smoke environment) level maps show a smoke environment and an evacuating behavior every moment.

The Change of Backlayer Length with the Ventilation Air Velocity in the Tunnel Fire (터널화재에서 환기속도와 backlayer의 길이변화)

  • 김성준;이민규
    • Fire Science and Engineering
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    • v.17 no.3
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    • pp.50-54
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    • 2003
  • The backlayer phenomena of smoke in the road tunnel is evaluated through numerical experiments. A commercial code, PHOENICS is used to simulate smoke flow in the road tunnel. The independent and dependent variables are ventilation air velocity and the length of backlayer of smoke respectively. Hybrid scheme and $textsc{k}-\varepsilon$ turbulence model is adopted in the simulation process and mass residual is used as a convergence criterion. The experimental results say that the length of backlayer is reduced linearly with the increase of ventilating air velocity and that there is a critical air velocity which prevents from the onset of backlayering phenomena. One finds that there is a fresh air region near the bottom of tunnel which could make the passenger escape from the region polluted by smoke. These phenomena come from the severe vertical stratification of the smoke air mixture in the tunnel.

Suggestion on the Optimal Length of Long Tunnels Considering Traffic Safety Characteristics (교통안전 특성을 고려한 장대터널 적정길이 제시)

  • Kim, Joong-Hyo;Lee, Jeong-Hwan;Kwon, Sung Dae;Ha, Dong Ik
    • Journal of The Korean Society of Civil Engineers
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    • v.34 no.1
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    • pp.203-211
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    • 2014
  • Tunnel reduces travel time as and it is essential facilities for the eco-friendly road construction. In recent years, It has been accelerating the tunnel construction to provide a higher level of traffic service but a driver driving in the narrow and dark tunnel takes characteristically psychological anxiety and the restriction of the sight. Moreover, A driver passing through more than 1,000m long tunnel, as to pass inside the monotonous form of the tunnel for a long time can cause drowsiness and increase the driver load. This driver load can degrade road-holding of the inside of the long tunnel highly and pose a high risk of accidents. Accordingly, In this study is to present the proper length of the Tunnel, considering the characteristics of traffic accident. For this, this study is that the long tunnel that affects traffic safety traffic safety variables are selected and classified. Traffic safety variables are classified in detail as a variable of the traffic accident and velocity one, the applicable variables the number of the traffic accident, the ratio of the traffic accident, driving velocity, the individual vehicle velocity etc. Traffic safety variables are categorized as more than a pole length of the tunnel in order to examine its impact on correlation analysis. The results indicate significant results in traffic accidents in accordance with traffic accidents, traffic safety, selects the variable was Variable depending on the length of the tunnel traffic safety point of significantly increasing the possibility of an accident can be seen as a high point. And the point of the Distribution of selected variables in order to create a traffic safety was a significant increase in traffic safety variables was set at critical intervals. Before reaching the critical point and the corresponding length of the long tunnel was set at the proper length. In this study, the optimum length of the proposed long tunnel through the long tunnel that occur in the future to contribute to reducing traffic accidents would be able to be determined.

Theoretical Study on the Characteristics of Pressure Change of High Speed Train in Tunnels (터널통과시 고속 철도 압력 변동 특성에 관한 이론적 연구)

  • Nam, Seong-Won;Kwon, Hyeok-Bin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.9
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    • pp.1042-1050
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    • 2004
  • Theoretical study has been conducted to clarify pressure characteristics of KTX(Korea Train eXpress) in tunnel. The severe pressure change in tunnel may give rise to the ear-discomfort for passenger and fatigue for car body. The external and internal pressure of rolling stock have been measured by using the running test with atmospheric pressure sensors and portable data acquisition system in high speed train. In this study, the tunnels from 200m to 4000m in length have been chosen for the investigation of tunnel length effects. We found that there are similar patterns of external pressure change for each critical tunnel length. The critical tunnel lengths are governed by train speed, train length and sonic velocity. And, the patterns of pressure wave in tunnel are classified into eight groups.

A Study on the x-t diagram Characteristics of Pressure Change of High Speed Train in Tunnels (터널에서의 고속철도 압력 변화의 x-t선도 특성에 관한 연구)

  • Nam, Seong-Won
    • Proceedings of the KSME Conference
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    • pp.1655-1660
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    • 2004
  • Theoretical study has been conducted to clarify pressure characteristics of KTX(Korea Train eXpress) in tunnel. The external and internal pressure of rolling stock have been measured by using the atmospheric pressure sensors and portable data acquisition system on Seoul-Busan high speed railroad line. These pressure change may give rise to the ear-discomfort for passenger and fatigue for car body. In this study, the tunnels from 200m to 4000m in length have been chosen for the investigation of tunnel length effects. From the results of experiment, the pattern of pressure change generally agrees to RTRI's experimental result for Shinkansen. We found that there are similar patterns of external pressure variation for each critical tunnel length. The critical tunnel lengths are governed by train speed, train length and sonic velocity.

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Theoretical x-t Diagram Analysis on Pressure Waves of High Speed Train in Tunnel (터널에서의 고속철도 압력파에 관한 X-t선도 이론 해석)

  • 남성원;권혁빈
    • Journal of the Korean Society for Railway
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    • v.7 no.3
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    • pp.200-207
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    • 2004
  • Theoretical study has been conducted to clarify pressure characteristics of KTX (Korea Train eXpress) in tunnel. The severe pressure change in tunnel may give rise to the ear-discomfort for passenger and fatigue for car body. Critical tunnel lengths which are induced by x-t diagram analysis can be applied to the experimental results measured by using the running test with atmospheric pressure sensors and portable data acquisition system in previous study. In this study, the tunnels from 200m to 4000m in length have been chosen for the investigation of tunnel length effects. We found that there are similar patterns of external pressure change for each critical tunnel length. The critical tunnel lengths are governed by train speed, train length and sonic velocity. And, the patterns of pressure wave in tunnel are classified into eight groups.

Behavior of Tunnel Face Reinforced with Horzontal Pipes (수평보강재로 보강된 터널 막장의 거동)

  • 유충식;신현강
    • Magazine of korean Tunnelling and Underground Space Association
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    • v.2 no.1
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    • pp.130-138
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    • 2000
  • 본 연구에서는 수평보강재로 보강된 터널 막장의 거동에 관한 매개변수 연구결과를 다루었다. 매개변수 연구에서는 막장주변의 3차원 응력-변형율 거동을 보다 효율적으로 모델링하기 위해 3차원 유한요소해석 모형을 적용하였으며 보강패턴에 따른 막장의 거동을 고찰하기 위해 다양한 경계조건에 대한 해석을 수행하였다. 해석결과를 토대로 막장의 응력해방-변위거동의 관계를 고찰하였으며, 보강패턴과 막장 변위의 정성${\cdot}$정량적인 관계를 제시함과 아울러서 향후 수행될 반경험적 설계/해석법의 개발을 위한 데이터베이스를 구축하였다. 한편, 해석결과 보강재 타설수 및 길이 등 각 보강설계 인자에 대한 임계치가 존재하는 것으로 나타났으며 따라서 보다 안전하고 경제적인 설계를 위해서는 이를 고려하여야 할 것으로 판단된다.

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A Study on the Characteristics of Internal and External Pressure Variation for KTX (KTX차량 내외부의 압력변동 특성에 관한 연구)

  • 남성원
    • Journal of the Korean Society for Railway
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    • v.7 no.1
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    • pp.26-31
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    • 2004
  • A study is conducted to clarify internal and external pressure variation of passenger cabin for KTX. These pressure variation may give rise to the ear-discomfort for passenger and fatigue for carbody. In this study, the pressure variation of interior, gangway and exterior of KTX passenger car is measured by using the atmospheric pressure sensors and portable data acquisition system. The tunnel from 4000m to 200m in length are chosen far the investigation of tunnel length effects. From the results of experiment, the pressure variation of interior per second is under the ear-discomfort limitation in all of tunnel. And, We found that there are similar patterns of exterior pressure variation for each critical tunnel length. These results generally agree to RTRI's experimental result fur Shinkansen.

Superconducting Properties and Tunneling Spectroscopy of Bi2Sr2Ca(Cu1-xNix)2O8+δ Film by LPE Method (LPE법으로 성장시킨 Bi2Sr2Ca(Cu1-xNix)2O8+δ 막(film)의 초전도특성 및 터널링 분광)

  • 이민수
    • Journal of the Korean Ceramic Society
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    • v.40 no.5
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    • pp.455-459
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    • 2003
  • Tunneling spectra of B $i_2$S $r_2$Ca(C $u_{1-x}$ N $i_{x}$ )$_2$ $O_{8+}$$\delta$/ film by LPE method have been measured using break junctions. The energy gap 2$\Delta$ and 2$\Delta$/ $k_{B}$ $T_{c}$ $^{zero}$ increased with increase of ft. We obtained the energy gap Parameter 2$\Delta$(4.2 K) = 54.4~64 meV, and corresponding1y $\Delta$/ $k_{B}$ $T_{c}$ $^{zero}$=7.36~10.14, larger than the BCS value. The lattice constant c and critical temperature $T_{c}$ $^{zero}$ decrease with increase of $\chi$$_{L}$.