• Tunnel and Underground Space
• /
• v.16 no.1 s.60
• /
• pp.85-94
• /
• 2006

In this study, scaled model tests were carried out to decide the optimal critical velocity, to prevent back layering in the case of fire in a long traffic tunnel. Realistic estimates were made for the time required for people to escape ken the tunnel and far the time required by the ventilation operator to increase the system speed to full capacity. The analysis, predicts that the emergency ventilation will start about 240 seconds after the tunnel fire. It was also found that prevention of back layering would occur within 4 minutes after fan operation. To find out optimal critical velocity, a 1/50 scaled model tunnel(diameter : 0.2 m and length : 20 m) based on the Froude similarity technique was constructed. Changing $\beta$ values in the Tetzner's equation, smoke propagation was observed. From the experiment, it was concluded that using a $\beta$ value of 0.5 to prevent back layering successfully allowed time for safe evacuation.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.18 no.3
• /
• pp.207-215
• /
• 2015

In the last decade, increasing national research fund for recycling the waste FRP (fiber reinforced plastics) ships which has caused environmental problems, improves the technology making concrete-reinforcing fibers out of the waste FRP. Furthermore, the concrete with recycled FRP fiber was tested for the structural performance. Experimental strength tests show that use of recycled FRP powder does not reduce the compressive strength of high strength concrete, and does increase the fire resistance performance of high strength concrete significantly. But, the study in investigating the properties of recycled fiber powder from waste FRP has not been completed because of the absence of the method of separation of mat layer from the waste FRP. This study is to propose a new extracting method of the mat layer from waste FRP, which is the efficient and environment friendly system. and thus it is considered to be the useful recycling method for fire resistance high concrete products or structures.

• Journal of the Korea Concrete Institute
• /
• v.14 no.4
• /
• pp.449-456
• /
• 2002

Recently, the application of high strength and high performance concrete has been gradually increased as an important construction material for high rise and huge scaled construction. However, high performance concrete has undesirable characteristics of spalling subjected to high temperature due to its dense microstructure content. A spalling by fire brings surface failure and falling off concrete member. It is considered that spalling by fire should be taken into account for the safety of the concrete structure under fire. Therefore, in this paper, tests are carried out using high performance concrete containing polypropylene(PP) fiber in order to improve the fire resistance performance. PP fiber contents and member sizes are varied. According to experimental results, as for the influence of PP fiber contents, all the test specimens without PP fiber show entire failure in W/C of 35％, while they show nearly sound shape except some kinds of surface fracture in W/C of 55％. When PP fiber is contained more than 0.07％, favorable prevention effects of spatting by fire are obtained. As for the effects of test specimens size, it tends to increase the possibilities of spatting by fire as test specimens become larger. And spatting by fire at the edge of test specimens occurs more frequently than at the surface of test specimens. Residual compressive and tensile strength shows 45∼65 ％ of its original strength at W/C of 35％, and 30∼40％ at W/C of 55 ％.

• Fire Science and Engineering
• /
• v.28 no.4
• /
• pp.21-28
• /
• 2014

This study obtained the following results by analyzing the standards related to a $1{\phi}$ 2W MCCB and evaluating its heat resistance characteristics. Since KS C 8321 corresponds to IEC 60947-2 standards, most of the related regulations are similar. The NFPA, which presents the user oriented safety regulations, contains no details about tests or inspections, etc., but it does specify in detail the regulations directly related to safety. It can be seen that KS C 8321 classifies in detail the items about tests and inspections. However, IEC 60947-2 and IEEE C37.51 simplified the test and inspection items or omitted some of them. When applying thermal stress to an MCCB for 6 hours at $180^{\circ}C$ using a heat resistant experimental device, it was found that the actuator lever was transformed and moved in the tripped state. In addition, most of the fixing hanger was melted down, losing their function. When applying thermal stress to the MCCB at $90^{\circ}C$, it showed nothing peculiar, but the fixing hanger was partly deformed at $105^{\circ}C$ and $120^{\circ}C$. It was found that the fixing hanger was deformed and the name plate was discolored at $150^{\circ}C$. It can be seen from the analysis of the internals of the MCCB that the trip bar has been melted away and that the up and down operator has moved up. The experiment performed by applying a withstanding voltage of 6 kV for 60 s showed that all items remained intact. In addition, the evaluation of the insulation performance performed by applying DC 500 V using an insulation-resistance tester showed good insulation performance.

• Journal of the Korea Concrete Institute
• /
• v.25 no.5
• /
• pp.497-508
• /
• 2013

This paper introduces a numerical model which can evaluate the fire-resistant capacity of reinforced concrete members. On the basis of the transient heat transfer considering the heat conduction, convection and radiation, time-dependent temperature distribution across a section is determined. A layered fiber section method is adopted to consider non-linear material properties depending on the temperature and varying with the position of a fiber. Furthermore, effects of non-mechanical strains of each fiber like thermal expansion, transient strain and creep strain are reflected on the non-linear structural analysis to take into account the extreme temperature variation induced by the fire. Analysis results by the numerical model are compared with experimental data from the standard fire tests to validate an exactness of the introduced numerical model. Also, time-dependent changes in the resisting capacities of reinforced concrete members exposed to fire are investigated through the analyses and, the resisting capacities evaluated are compared with those determined by the design code.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.3
• /
• pp.607-617
• /
• 2023

This study aims to analyze whether the performance of the fire extinguisher meets the criteria for the apparent specific gravity property test by calculating the change in internal pressure and the use period of the fire extinguisher as a new one with 5 years, recycled one with 5 years, a new one with 10 years, and a new one with 13 years, respectively. As a result of the experiment, when the internal pressure of the fire extinguisher was 0%, the first, second, and third arithmetic mean analysis of the dry chemical extinguisher according to the use period was found to be condemned. When the internal pressure of the fire extinguisher was 50%, it was measured as 130 ml in sample 12-08-new and analyzed as unsuitable. Also, sample 09-09-new of a new dry chemical extinguisher with 13 elapsed years measured 145ml, which was found inappropriate. All other dry chemical extinguishers were analyzed to be suitable. All were noted suitable when having normal internal pressure of the fire extinguisher, except for sample 09-06 of a new dry chemical extinguisher with 13 elapsed years, which was determined to be unsuitable caused by measuring as 131 ml for experimental value. As a result of experiments, some of the apparent specific gravity tests of dry chemical extinguishers from 10 years to 13 years have found that they are unsuitable for the performance of the fire extinguishers due to the massive phenomenon. Accordingly, it is necessary to reduce the endurance period of dry chemical extinguishers from 10 years to 7 years.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.145-148
• /
• 2004

The purpose is to prove the newly established 'UNBONDED CAPPING' method for Concrete Strength Tests. Day by day, concrete buildings and structure became high-rising and magnificently vast scheduled, as contributed from the development of improved equipments that suitable to specific construction works and high qualitied Admixture, the qualities of the concrete was highly improved. It is very important that the concrete strength tests and evaluation should be carried out in the manner that as soon as the concrete is placed so that dismantling form works can be done in time and that may enabling reducing construction period directly related with the costs of the project. However, the conventional capping method of concrete specimen requires more manpower and consuming times, As for the Sulfur capping, there may be incurred accidential fire and generation of Gas, what is more there stands limitation in precise evaluation of strength test results because of variation in capping method results may vary in concrete strength test results. Not necessarily emphasize, the compression strength of the concrete is the most valuable basic data essential to control the qualities of the concrete and that should be carried out accurately. in this study evaluation of the compressive strength test results comparing stabilized concrete capping method for Cement Paste capping, Sulfur-paste capping ,High Gypsum capping and recently flowing the Grinding with the UNBONDED CAPPING' method to provide reliable and economical concrete strength testing.

• Fire Science and Engineering
• /
• v.20 no.4 s.64
• /
• pp.26-32
• /
• 2006

Nowadays in Korea, KS F 2271 has been using for the test of fire safety performance of sandwich panels. Smoke toxicity test is the test for the toxicity evaluation of smoke and hazardous gas, caused by combustion of building materials and finishing materials. Smoke toxicity can be evaluated by the mean incapacitation time of mice; however this method is not a quantitative way. This test result can be influenced by the health status of mice and test condition. Specific optical density can be quantitatively measured by ISO 5659-2 single chamber method and toxic gases can be quantitatively measured by FTIR analysis. In this study, specific optical density of sandwich panel insulations, which are widely used in Korea, were tested using the ISO 5659-2 single chamber test method and compared with each test. Also, in the second test of three tests for each specimen, FTIR analysis was performed and quantitative test results(HCl, $NO_2$, etc) were compared with each test result.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.283-284
• /
• 2009

The purpose of this study is to investigate the spalling resistance of super high strength concrete with polypropylene(PP) fiber after 3 hours unstressed fire test. Tests have been carried out as a function of PP fiber quantity and concrete strength(100MPa, 150MPa). The results indicate that the spalling resistance will be achieved in suitable amount of PP fiber.

• 한국전산유체공학회:학술대회논문집
• /
• 2010.05a
• /
• pp.17-20
• /
• 2010

An aerial target system is used for the purpose of experimental test and fire training of missile that newly developed and in mass production. Since the target drones of aerial target systems are monopolized by several major countries so that they are selling at a high price. In this paper, we present the CFD simulation results on a new target drone that Kyungan co. ltd is developing with their own technologies. The presented CFD simulation was conducted in the same conditions of a wind tunnel tests and we could obtain the simulation results of the lift and drag values were in errors by less than 15 percent compared to the experiment. The simulation results were used to determine the modified shapes of new prototype target drone that could fly safely.