• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.36-36
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• 2000

KSTAR 토카막은 보조가열 장치로 2005년까지 1대(최종적으로는 2대)의 중성입자빔 입사장치(NBI)를 설치하여 장치의 기본 설계값에 도달할 예정이다. KSTAR NBI는 3개의 이온원을 가지고 있으며 총 수소 유입량은 70 Torr.L/s인 반면 고속 중성 입자빔량은 모두 11 Torr.L/s로 기체 배기량은 59 Torr.L/s에 달하고 압력은 장소에 따라 10-5~10-6 Torr로 유지되며 총배기속도가 1~2$\times$106 L인 펌프가 필요하다. 이때 크라이오 펌프(cryopump) 방식이 거의 유일한 해결책이라고 할 수 있다. 크라이오 펌프는 고속 입자빔 수송로의 양편에 각각 설치되는데 총면적 30m2 내외의 극저온 냉각판(cryo-pnael)들과 이를 상온 열복사로부터 보호하기 위한 열차폐(thermal shield) 및 흡기구 배플(baffle), 그리고 적절한 냉각장치로 구성된다. 시운전 단계에서는 15K GM 냉동기와 활성탄이 부착된 냉각판을 사용하는 방식과 4K GM 냉동기로 냉각하는 방식이, 최종 운전단계에서는 3.7K 액체 헬륨을 사용하는 방식이 고려되고 있다. 크라이오 펌프의 구조설계에 앞서 우선 배기속도, 흡？량, 작동압력, 냉각판 온도, 열손실량 등 설계사양을 확정하고 정리하는 일이 진행되고 있다. 또 냉각방식과 상관없이 동일한 개념으로 만들어지는 배플과 열차폐의 최적설계를 위한 몬테카를로 계산과 열전도 계산을 병행하고 있다. 이 곳에서는 KSTAR NBI 장치의 주배기계로서 사용될 크라이오 펌프의 설계방향과 전반적인 구조 및 예상성능 등에 대해 발표하려고 한다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.6
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• pp.451-462
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• 2011

The smoke control system plays the most important role in securing evacuation environment when a fire occurs in road tunnels. Smoke control methods in road tunnels are classified into two categories which are longitudinal ventilation system and transverse ventilation system. In this study it is intended to review the characteristics of smoke behavior by performing numerical analysis for calculating the optimal smoke exhaust air volume with scaled-model and simulation when a fire occurs in tunnels in which transverse ventilation is applied, and for obtaining the basic data required for the design of smoke exhaust systems by deriving optimal smoke exhaust operational conditions for various conditions. As a result of this study, when the critical velocity in the tunnel is 1.75 m/s and 2.5 m/s, the optimal smoke exhaust air volume has to be more than $173m^3/s$, $236m^3/s$ for the distance of the smoke moving which can limit the distance to 250 m. In addition, in case of uniform exhaust the generated smoke is effectively taken away if the two exhaust holes near the fire region are opened at the same time.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.917-930
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• 2018

A quantitative risk assessment method for quantitatively evaluating the fire risk in designing a road tunnel disaster prevention facilities has been introduced to evaluate the appropriateness of a disaster prevention facility in a large tunnel through which all vehicle types pass. However, since the quantitative risk assessment method of the developed can be applied only to the large sectional area tunnels (large tunnels), it is necessary to develop a quantitative risk assessment method for road tunnels passing only small cars which has recently been constructed or planned. In this study, fire accidents scenarios and quantitative risk assesment method for small road tunnels through small cars only which is based on the methods for existing road tunnels (large tunnels). And the risk according to the distance between cross passage is evaluated. As a result, in order to satisfy the societal risk assessment criteria, the distance of the appropriate distance between cross passages was estimated to be 200 m, and the effect of the ventilation system of the large port exhaust ventilation system was quantitatively analyzed by comparing the longitudinal ventilation system.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.3
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• pp.375-388
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• 2017

In order to solve the traffic congest and environmental issues, small-cross section tunnel for small car only is increasing, but there is not standard for installation of disaster prevention facility. In this study, in order to investigate the behavioral characteristics of thermal environment and smoke in a small cross section tunnels with a large port exhaust ventilation system, the A86, the U-Smartway and the Seobu moterawy tunnel, Temperature and CO concentration in case of fire according to cross sectional area, heat release rate and exhaust air flow rate were analyzed by numerical analysis and the results were as follows. As the cross-sectional area of the tunnel decreases, the temperature of the fire zone increases and the rate of temperature rise is not significantly affected by heat release rate. However, there is a difference depending on the change of the exhaust air flow rate. In the case of applying the exhaust air flow rate $Q_3+2.5Ar$ of the large port exhaust ventilation system, the temperature of the fire zone was 7.1 times for A86 ($Ar=25.3m^2$) and 5.4 time for U-smartway ($Ar=37.32m^2$) by Seobu moterway tunnel ($Ar=46.67m^2$). The CO concentration of fire zone also showed the same tendency. The A86 tunnels were 10.7 times and the U-Smartways were 9.5 times more than the Seobu moterway. Therefore, in the case of a small section tunnel, the thermal environment and noxious gas concentration due to the reduction of the cross-sectional area are expected to increase significantly more than the cross-sectional reduction rate.