• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.488-494
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• 2019

Precision Guided Missiles after production and militarization have various characteristics that enable the final performance to be identified by conducting live-fire tests after long-term storage. Likewise, the performance and reliability of ${\bigcirc}{\bigcirc}$ Missiles, which are currently used by the Korean Navy, are also verified consistently by conducting live-fire tests after militarization. Specially, the live fire test at '00 year, which was conducted by Korean Navy, showed the result that 'Ring', which is a component of the canister's front cover, was jammed with wings for propulsion and then broke away from the canister during the missile launch process. This situation led to an interruption of the deployment of wings and finally affected the missile's flight performance. The results of a survey of the canisters of those missiles whose live fire tests were conducted successfully, based on the live fire test at '00 year, showed the 'Ring's separation from canisters. This raises recognition for the need to solve the problems of 'Ring's separation and breakaway. This study suggests an improvement derived by the result of live-fire tests and introduces the effect of final launch performance of ${\bigcirc}{\bigcirc}$ Missiles and test result after applying the improvement.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.113-116
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• 2009

This study analyzed fire-resistant characteristics according to changes in repair methods of PFH mixed high-strength concrete roof structures having undergone fire damage. The results of the study are as follows. First, as a repulsive characteristics of structures, the remaining repulsion was shown to increase following fire-resistance tests according to increases in depth of coverings. The results of the relationship between depth of coverings and remaining repulsion rates following fire-proofing tests showed a high correlation. At a covering depth of 67.3mm, remaining repulsion rate was estimated to be 100%. For fire-resistant characteristics following repairs of structure, as for spalling, severe separation was shown in the case of general plaster while general plaster + Metal Lath showed overall superior spalling prevention. For internal structure temperatures, general plaster showed max temperatures of 705℃, average temperatures of 636℃ while general plaster + metal lath showed max temperature of 660℃ and average temperature of 520℃, demonstrating lower temperature distributions than use of only general plaster. In conclusion, after removing the covering of structures damaged due to high temperatures of fires within high-strength concrete installations, the use of fire-resistant mortars and applying metal laths on surfaces of general plaster will provide superior fire-resistance performance in the occurrence of a 2nd fire.

• Journal of the Korean housing association
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• v.18 no.5
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• pp.133-141
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• 2007

The purpose of this study is to secure an evacuation time and to ensure safety by using an Ubiquitous Sensor Network computing when a fire breaks out at a super high-rise apartment housing. A super high-rise apartment housing that is a type of building to solve the problem of separation of the urban function and the phenomenon of hollowing out downtown has been on the increase, high-rise apartment housings occupying 52.7% of whole housings in 2005. However, if a fire breaks out, there would be serious damage since it accommodates many people and facilities as existence of vertical gigantism in the city. The architectural law in force has no clause on it which is universally applicable to general building, it is difficult to be applicable to a densely super high-rise apartment housing and there would be in danger of a resident's evacuation in the fire. Therefore, as a previous study to introduce an USN-based fire-warning facility and evacuation equipment, this study shows the improvement way after analyzing factors that are barriers to evacuaee's behavior of a super high-rise apartment housing and also shows establishment of the grade of vertical evacuation rank by SimuleX, one of the best computer simulation program.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.560-565
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• 2006

Sprinkler system is the most effective fire suppression with high confidence among active fire extinguishing systems. According to the installation of the related system on buildings, more separation area of fire protection can be considered to the fire protection design, and also lower differential pressure (12.5 Pascal) is permitted on lobby of fire escape stairs and emergency elevator (25 Pascal shall be considered for none sprinkler system) with economic factor. More details will be handled on the related studies.

• Journal of the Korea Society for Simulation
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• v.30 no.3
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• pp.31-39
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• 2021

During artillery fire, an excessive level of impulse noise propagating in the form of a storm wave is generated. Since the sound of impact from the fire affects the stability of the surrounding structures, the artillery and the structures must be separated from each other by the proper distance to avoid damages from friendly fire. However, if they have already been built within the distance, it is possible to prevent the damages by building sound barriers between them. In this study, the proper separation distance between the artillery and the structure was calculated, and the insertion losses due to various heights and shapes of the sound barrier were simulated by using the BEM(Boundary Element Method), and conclusively the optimal sound barrier was selected.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.1
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• pp.67-73
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• 2007

Recently, fire extinguishing systems based on water mists have been attracting public attentions in marine engineering. Performance of fire extinguishing systems is very strongly influenced by the size and distribution of spayed water mists. Therefore, the present study has developed droplet analyzing method based on image processing. The morphological technique based on partial curvature information of pre-processed images with relaxation method was adopted for recognition and separation of overlapped particles. Tested results showed that the present method may be reliable for the analysis of the size and distribution of droplets in spray flow of fire extinguishing systems based water mists.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.67-72
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• 2000

Demand for now nondestructive evaluation are growing to detect fatigue crack growth behavior to predict long term performance of materials and structure in aggressive environments especially when they are In non-visible area. Acoustic emission technique is well suited to these problems and has drawn a keen interests because of its dynamic detection ability, extreme sensitivity and location of growing defects. In this study, we analysed acoustic emission signals obtained in fatigue and tensile test of high strength fire resistance steel for frame structure with time-frequency analysis methods. The main frequency range is different in the noise and the fatigue crack propagation. It could be classified that it were also generated by composite fracture mechanics of cleavage, dimple, inclusion separation etc.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.535-547
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• 2021

A policy to expand the hydrogen economy has been established in Korea and the supply of FCEV is being expanded to realize a hydrogen society. Therefore, the supply of FCEV is expected to increase rapidly, and a solution to respond to accidents of FCEV is required. In this study, an experimental study was conducted to analyze the effect of the hydrogen jet flame generated by a FCEV on the inner wall of the tunnel and the characteristics of the internal radiant heat. For the experiment, the initial pressure of hydrogen tank was set to 700 bar, and the injection nozzle diameter was set to 1.8 mm in order to make the same as the conditions generated in the FCEV. In addition, a tunnel fire resistance test specimen having the same strength as the compressive strength of concrete applied to general tunnels of 40 MPa was manufactured and used in the experiment. The results were analyzed for the separation distance (2 m and 4 m) between the hydrogen release nozzle and the tunnel fire resistance test concrete. As the result, the maximum internal temperature of the test concrete was measured to 1,349.9℃ (2 m separation distance), and the radiant heat around the jet flame was up to 39.16 kW/m².

• Journal of the Society of Disaster Information
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• v.10 no.4
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• pp.598-608
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• 2014

The first operation of alarm system starts at a detector. And the largest effect is produced on the operation of detector by the fire source position and installation position. Nevertheless, the Korean standard for the installation of detector only specifies matters of fire detector installation according to area and height, without consideration of installation position and fire source position. Therefore, this study carried out a fire test in consideration of detector installation position and fire source position (5 places) in order to minimize casualties owing to the fast operation of fire detector when a fire occurred. Considering that it took the longest time for a detector close to a wall to work in the results of this test, it was possible to find that a minimum clearance to the wall was required.

• Fire Science and Engineering
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• v.22 no.1
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• pp.16-23
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• 2008

In this research, the visualization experiment for a scaling tunnel was conducted to establish the optimum fire protection system in tunnel fires. In order to find the optimal operating condition of jet fan with the fire, the characteristics of smoke propagation was considered to find the optimal operating condition of jet fan at the time of tunnel fire, the concentration of smoke was measured experimentally for various jet fan position and it's operating condition. As a result, when jet fan in the vicinity of fire operates at the upstream, the back-layering of the smoke should be considered with separation distance from the fire source. The distance between the jet fan and the fire should be longer than 50 m. On the other hand, when the vicinity jet fan operates at the downstream, the back-layering of smoke does not occur, but stratification is not maintained because the smoke dispersion occurs at the downstream due to the operation of the jet fan.