• Journal of Korean Tunnelling and Underground Space Association
• /
• v.15 no.6
• /
• pp.585-597
• /
• 2013

In this study, in order to evaluate stability of the room-and-pillar underground structure, a series of preliminary numerical analyses were performed. Design concept and procedure of an underground structure for obtaining a space are proposed, which should be different from structural design for the room-and-pillar in mine. With assumed material properties, a series of numerical analyses were performed by varying size ratios of room and pillar and then the failure modes and location at yielding initiation were investigated. From the results, relationship between the ratio of pillar width to the roof span (w/s) and overburden pressure at failure initiation shows a relatively linear relation, and the effect of w/s on structural stability is much more critical than the ratio of pillar width and height (w/H) which is a crucial parameter in design of the room-and-pillar mining. It means that roof tensile failure and shear failure at shoulder and pillar are necessary to be considered together for confirming overall structural stability of the room-and-pillar structure, rather than considering the pillar stability only in mining. Failure modes and location at failure initiation were varied with respect to the ratio of room and pillar widths. Therefore, it is necessary to simultaneously consider stability of both roof span and pillar for design of underground structure by the room-and-pillar method.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.1
• /
• pp.461-468
• /
• 2022

This study is focused on the ignition of ceiling insulation depending on working condition of Sprinkler head in underground parking lot fire. When temperature changes of same point were measured depending on sprinkler's working condition, in Scenario 1, inner temperature at border of spray applied material(SP-2) of ceiling part near the fire and ceiling insulation(blowing polystyrene) was 658.27℃ and its which inner maximum temperature is higher than 427℃ which is the ignition point of ceiling insulation(blowing polistyrene), so it was observed that flame is ignited on the ceiling insulation and spread fire. In scenario 2, Inner fire temperature at border of spray applied material(SP-2) and ceiling insulation(blowing polystyrene) near the fire was 53.10℃ and it was lower than ignition point so it was observed that flame was not ignated on the ceiling insulation. As a result, it was foreseen that possibility of ignition on the ceiling insulation depending on working condition of sprinkler.

• The Journal of the Korea Contents Association
• /
• v.9 no.3
• /
• pp.345-352
• /
• 2009

The glass ceiling is defined as a barrier so subtle that it is transparent, that it prevents women and minorities from moving up in the management hierarchy. Individuals in the minority may perceive the presence of a glass ceiling within their social context, a barrier put in to place by those in the advantaged majority. This study has testified pragmatically the influence of glass ceiling perceived by the female employees of travel agency on their work attitudes(organizational commitment, turnover intention). Data were collected by 202 full time female employees. The results of analysis is as follows: First, it is revealed that glass ceiling has no influence on turnover intention. Second, this study show that the higher glass ceiling is perceived by the female employees of travel agency, the more they have negative influence on their affective commitment. Contrary to our expectation, however, it is revealed that glass ceiling has no influence on continuance commitment. That is, glass ceiling have significant effects on affective commitment whereas the effects are not significant for continuance commitment. Third, affective commitment have significant effects on turnover intention. However, it is revealed that continuance commitment has no influence on turnover intention.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2010.04a
• /
• pp.84-89
• /
• 2010

본 연구에서는 공기를 Fresh-water, 화재를 Salt-water로 치환하여 밀도차에 의한 Salt-water 확산의 화재 모사 적용성을 기초적으로 검증한다. 실험은 Zone model과 Field model의 화재해석 결과 나타난 천장부 확산, 와류 발생, 연기층 하락, 연기층과 공기층의 구분 등의 특징을 분석 기준으로 하며 Salt-water에 Tracer를 첨가하여 PIV(Particle Image Velocity) 분석법을 통해 확산현상에 대해 분석하였다. 결과로 Salt-water의 용해도가 높을수록 천장부 확산, 와류 발생, 연기층 하락, 연기층과 공기층의 구분에 있어 실제 화재와 유사한 것으로 판단되며 최소 15.0%이상의 용해도에서 이와 같은 현상이 뚜렷해지는 것으로 분석되었다. 본 연구를 통해 축소모형 화재 모사시 발열 상태가 아닌 다른 방법으로의 모사가 가능한 것이 증명하였다.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.5
• /
• pp.454-465
• /
• 2020

Fire simulations were performed using the Fire Dynamics Simulator (FDS) software to examine the vent flow and temperature in the engine room of a small ship. A diesel fire with a heat release rate of 10 kW was targeted, and the effects of the ceiling duct location, side vent existence and nonexistence, and side vent size were investigated. The existence or nonexistence of the side vent and its size considerably affected the smoke behavior, mass flow rate through the vent, and temperature. When the side vent was not installed or was small, the smoke layer reached the floor in the engine room. In addition, as the side vent size increased, the mass flow rate through the vent increased with decreasing temperature value. However, the effects of the ceiling duct location on the smoke behavior, mass flow rate through the vent, and temperature seemed to be relatively minor compared to those of the side vent size. Therefore, to improve the fire safety of the engine room in a small ship, the side vent size is considered to be a more important design factor than the ceiling duct location.

• The Journal of the Acoustical Society of Korea
• /
• v.24 no.1
• /
• pp.21-28
• /
• 2005

In this Paper, the effect of stage ceiling height on the acoustic characteristics of rectangular concert halls are investigated. To find out the acoustic properties of audience area, A simple Boston Symphony Hall(BSH) model which is typically rectangular shaped was applied for computer simulation. A newly built rectangular concert hall with 400 seats was also chosen for a scale model $(1.2m{\times}0.68m{\times}0.31m)$ study and its computer simulation varing the stage ceiling height and the volume. The results show that RT increased as the stage ceiling was lowered and the difference rate of RT by its variance is from -0.09 to -0.06[sec/m].

• Journal of the Society of Disaster Information
• /
• v.15 no.1
• /
• pp.98-108
• /
• 2019

Purpose: The purpose of this study is to test the sprinkler performance to protect the wall and ceiling joints of the sandwich panel warehouse in case of fire. Method: Based on the field surveys, test was setup and combustibles were prepared. The sprinkler discharge tests were performed at the corner of the wall and right under the sprinkler head. Results: It has been found that operation of the K-80 closed sprinkler head prevents the ignition of the sandwich panel and therefore no damage to the joints of sandwich panels. To prevent skipping phenomenon, it is necessary to install the sprinkler head from the corner of the wall and to keep a minimum distance of 2.4m and a maximum distance of 3m. Conclution: A Standard Operation Procedure should be prepared to suppress and rescue of fire brigade for a sandwich panel warehouse protected by perimeter sprinklers preventing a ignition of core materials and control fire.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2011.11a
• /
• pp.179-182
• /
• 2011

본 연구는 목조 건축물의 규모(높이)에 따른 수계 소화설비의 화재 진압 성능을 비교하여 최적의 소화설비를 선택함을 목적으로 한다. 높이 2.5m(소), 4m(중), 5.5m(대)의 모형화재실을 제작하고 모형화재실 천장에 스프링클러헤드와 미분무헤드를 설치, 소화실험을 진행하여 천장부 온도변화 및 소화시간, 방수량을 측정한다.

• Fire Science and Engineering
• /
• v.21 no.4
• /
• pp.18-24
• /
• 2007

The purpose of this study is focussed on the numerical predictions of temperature distribution by radiation heat transfer in atrium fire using the field fire model and the CCRHT-3D code. This code uses standard $k-{\varepsilon}$ turbulent model with SIMPLE algorithm and weighted sum of gray gases model regrouping(WSGGM-RG). The WSGGM-RG calculates radiative properties on the reduced computational loads while reserving the accuracy. The numerical results show that lower temperature distributions on the wall and the top ceiling wall can be obtained by considering radiative heat transfer. The temperature on the top ceiling wall can be an important parameter in predicting the operating condition of the sprinkler head.

• Fire Science and Engineering
• /
• v.22 no.1
• /
• pp.93-98
• /
• 2008

Full-scale fire extinguishment tests were conducted to develop loaded stream fire extinguishing systems for protecting underground transmission cables. The dimension of test mock-up was 5.5m height${\times}3m$ width ${\times}6m$ length, and six 154kV OF cables were piled up. Gasoline was used to ignite cates. Linear heat detection cables were installed on top of 154 kV OF cable and discharge nozzles were installed on the top and sidewalls, respectively. As a result, both surface fires and deap-seated fires were extinguished successfully within the specified 3 minutes by discharging loaded stream agent.