• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2009.04a
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• pp.487-492
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• 2009

This study was performed FE numerical analysis under 120-minute fire conditions, using the ABAQUS, a wide use software, on the basis of the test results by concrete tunnel lining fire strengths (ISO, RWS, and MHC). The concrete material test was to secure the material properties of concrete linings, which were numerical analysis input conditions. And then built the material properties, such as specific heat, heat transfer rate, heat expansion rate, density, elasticity coefficient and compression strength under high temperature conditions, as database at 20 $^{\circ}C$ to 800 $^{\circ}C$, applying them to analysis as input values. As a result, the tunnel linings under RWS fire conditions saw fire temperature rose to maximum 1119 $^{\circ}C$at the location of 5 mm above a thermal surface, and saw surface temperature amount to 1214 $^{\circ}C$ in the middle part.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.4
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• pp.313-327
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• 2008

Thermo-mechanical coupled behavior of an underground structure during a fire accident have not been fully understood yet. Moreover, when such a thermo-mechanical coupled behavior is not considered in numerical analyses based on conventional heat transfer theory, fire-induced damage zone in an underground structure can be considerably underestimated. This study aims to develop a FEM-based numerical technique to simulate the thermo-mechanical coupled behavior of an underground structure in a fire accident. Especially, an element elimination model is newly proposed to simulate fire-induced structural loss together with a convective boundary condition. In the proposed model, an element where the maximum temperature calculated from heat transfer analysis is over a prescribed critical temperature is eliminated. Then, the proposed numerical technique is verified by comparing numerical results with experimental results from real fire model tests. From a series of parametric studies, the key parameters such as critical temperature, element size and temperature-dependent convection coefficients are optimized for the RABT and the RWS fire scenarios.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.194-200
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• 2010

Recently, a longitudinal tunnel construction has increased because of subway construction extension, geomorphological effect and the development of construction Technologies etc. When the fire occurs in a tunnel and an underground structure, the many damage of human life and the economic losses are caused. In Korea, fire resistance character study of a tunnel and an underground structure is proceeding. However, when a concrete is exposed to high temperature, study of load carrying capacity reduction and stability evaluation for spalling of a concrete is not enough. Therefore in this study, fire resistance character of a concrete evaluated according to time heating temperature curve(RABT and RWS) and a result compared on virtual fire accident in order to apply fire scenario. Also this study performed thermo-mechanical coupled analysis of a FEM-based numerical technique and estimated fire-induced damage of a tunnel and an underground structure.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.2
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• pp.165-176
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• 2005

A variety of research projects have been undertaken due to the recent catastrophic tunnel fires throughout the world, Among them, more emphasis was given to full scale and scale model fire experiments, and recently the area of fire resistance of tunnel structures attract more interests, On the contrary to the cases in most of the advanced countries where design standards as well as recommendations have already been announced, no local criteria for design can be found, This paper aims at deriving the fire characteristics appropriate for the assessment criteria of fire resistance of structures in local tunnels through studying the existing fire temperature curves including ISO 834 standard temperature curve, HC curve, RWS curve, ZTV curve and EBA curve.

• Journal of the Korean Society of Food Science and Nutrition
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• v.2 no.1
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• pp.23-30
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• 1973

Wistar strain male rats were divided into four different diet groups and the control group was fed on 7-percent casein diet (C), the second with a mixture of 80% of rice and 20% of buckwheat (RW), the third with rice only (R), and the fourth with a mixture of rice and buckwheat of equal nitrogen level (RWS). Each diet group consisted of 6 rats was fed for three weeks by the ad libitum feeding method. The results of the experiment, i.e., the growth gain and change in the level of free amino acids in the plasma and liver determined by the micro-bioassay method were as follows. 1. The group C showed the largest growth gain and the rest did in the order of RW group, R group. and RWS group. 2. Rats fed on diet of high protein score showed high level of free amino acids tryptophan, lysine, and threonine in the plasma and liver except for the case of lysine in the liver. 3. Protein score would be estimated by the level of free amino acids in the liver and plasma.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.705-708
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• 2008

To obtain tunnel concrete safety in case of fire, this study analyzed fire proof characteristics by fire proof method change, and the results are as follows. As a fire proof characteristics by RABT temperature heating curve, plain concrete experienced severe spalling by initial extremely high temperature. In view of fire proof method, in the cases of organic fiber mixing method and board method, spalling was prevented, and in the case of spray method, severe spalling of over 100mm depth occurred along with exposure of structural concrete including spray coat by heat stress, etc while metal lath, the stiffener, falls off. As for fire proof characteristics by RWS temperature heating curve, in case of organic fiber inclusion, concrete surface experienced fusion of within 5mm, while in the case of spray method, spray coat was severely spalled to a depth of over 100mm causing structural body concrete to expose its reinforcement, and also in the case of board method, board was fused by high temperature, causing structural body concrete be directly exposed to high temperature, which triggered overall fall-off phenomenon, so in such extraordinary high temperature heating condition, establishment of special fire proof measures is needed.

• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.262-269
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• 2023

Purpose: In this study,fire-resistance test were executed to evaluate the effectiveness of the fireproof panel attached to the PSC slab in tunnel. Method: For the fire resistance test, the RWS curve was applied and the furnace of the KICT was used. Result: As a result of the experiment, the maximum temperature measured on the concrete surface of the PSC slab with the fireproof panel was 321.8℃, which was lower than the damage limit temperature of 380℃ for concrete. Also, at the t=25mm, the maximum temperature was 35.2℃, which was lower than the damage temperature of steel, 250℃. The use of precast fire resistance panel(t=30mm) improves fire resistance of PSC structures. Conclusion: As a result of the test, a reinforcement method for attached a fireproof panel in case of fire in a tunnel or an underground roadway is provided to protect a structure from fire. In the future, it is necessary to perform the static performance test of the slab to which the fireproof panel is attached, and to confirm the adhesion performance of the fireproof panel by performing the pull-off test and the fatigue test.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.423-430
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• 2005

Fire accidents in underground space may bring much loss of lives as well as properties and result in catastrophic disasters. This study aimed to manufacture the high-temperature furnace capable of simulating fire scenarios (RABT and RWS) and carry out the preliminary fire tests to evaluate fire-induced damage in underground structures. Specimens used in the fire tests were the concrete segments generally used in shield TBM tunnels. The simulated fire scenario was set to the RABT curve that is the most representative fire scenario in underground space. From the fire tests, the spalling was estimated to reach approximately 20cm from the surface exposed to fire. In addition, from the observation of core specimens obtained after fire tests, the deteriorated zone of unspalled specimens amounted to approximately 10cm from the surface of spalling.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.236-243
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• 2007

Steering systems are classified as FWS(front-wheel steering), RWS(rear-wheel steering) and AWS(all-wheel steering) according to steering position. AWS is effective to reduce turning radius and platform length because all wheels are steered. Although various rear wheel control logics for AWS were developed, these are applied to four wheel steering cars. Therefore new control logics must be developed to apply articulated vehicles. In the present study, it is suggested how to control the real wheels based on the virtual rigid axles and also how to set it to minimize the turning radius.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.4
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• pp.389-393
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• 2017

Purpose: The aim of this study is to evaluate the flexural strength of flexible resins and the flexibility of different resin splint (RS) systems in comparison with resin wire splint (RWS) system. Materials and methods: Three different resin materials (G-aenial flo, GA, GC; Superbond, SB, Sun medical; G-fix, GF, GC) were tested flexural strength test in accordance with ISO-4049:2000. For the flexibility test of splint systems, a artificial model with resin teeth was used to evaluate three types of resin splint systems (GA, SB, and GF) and one resin wire splint system. The left central incisor was simulated 'injured teeth' with third degree mobility. Three consecutively repeated measurements of periotest value were taken in horizontal direction, before and after splinting to access tooth mobility. The splinting effect was calculated through the periotest value. Differences were evaluated through One-way Anova and Tukey HDS post-hoc tests for pair-wise comparison (${\alpha}=.05$). Results: Although GA group showed significant higher flexural strength than SB and GF groups, all of three different resin splint systems produced a significantly higher and rigid splinting effect compared with 016" resin-wire splint system (P < .05). Conclusion: Within the limits of an in vitro study, it can be stated that resin splint systems are too rigid and may not be acceptable to treat tooth avulsion.