• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.7
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• pp.764-774
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• 2008

A fire-out-of-battery(FOOB) mechanism, which is a new recoil technology, can reduce dramatically the level of a recoil force compared to the conventional recoil system. The FOOB mechanism pre-accelerates the recoil parts in direction opposite of conventional recoil before ignition. This momentum of the recoil parts due to pre-acceleration can reduce the firing impulse. In this paper, the dynamics of the recoil system with this FOOB mechanism is formulated and simulated numerically. The results of the simulation show that the FOOB system can reduce the recoil force and stroke compared to the conventional system under normal condition. When the fault modes happen, the FOOB system may not perform well and may be damaged seriously due to excessive recoil force and stroke. Hence, the control of the fault modes is necessary to achieve the normal operation of the FOOB system. The results that an additional MR damper enables the FOOB system to perform well under all firing condition.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2004.06a
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• pp.170-175
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• 2004

• Journal of the military operations research society of Korea
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• v.29 no.1
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• pp.8-27
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• 2003

This paper develops a methodology that can be used to quantify the assesment of power improvement effectiveness of corps level C4I system applied to integrated fire operation by adapting Schuzer's C2 theory. This paper first describes how C4I systers can enhance the battle outcome in three way. : (1) Enhanced unit probability of survival; (2) Enhanced unit's individual effectiveness; improved exchange ratios; (3) Improved task force allocations : increased percentage of assets that can be assigned to a given engagement These enhancements are then show to result from improved probability of detection through information sharing; improved survivability and lethality through battle force coordination; and enhanced force allocation and prepositioning through improved timeliness of information(more advanced warning). It demonstrates that well-designed C4I systems can be shown to represent a significant force multiplier on the outcome of the battle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.560-564
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• 2007

In order to reduce the level of recoil force, new recoil technology must be employed. The present study discusses a soft-recoil mechanism that can reduce dramatically the recoil force. The dynamics of the soft-recoil system with hydraulic dampers are described and simulated. The results of the simulation show that FOOB system can reduce the recoil force and the recoil stroke compared to conventional systems. However, the FOOB system is not able to perform well when the fault modes happen. Hence, this study uses the MR damper to achieving FOOB under fault modes.

• Tunnel and Underground Space
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• v.25 no.6
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• pp.568-576
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• 2015

In this study, scenarios based on the leakage of highly compressed air and fire occurrence turned out to be high risks in an operation stage of CAES facility were constructed and estimated. By combining Bernoulli equation with momentum equation, an expression to calculate an impact force of a jet flow of compressed air was derived. An impact force was found to be proportional to the square of diameter of fracture and the pressure of compressed air. Four types of fire scenarios were composed to evaluate an effects that seasonal change and location of fire source have on the spread behavior of smoke. Smoke from the fire ignited in the vicinity of CAES opening descended more quickly below the limit line of breathing than one from the fire occurred 10 m away from CAES opening, which is expected to occur due to a propagation of wave front of smoke. It was shown that a rate of smoke spread of the winter fire is faster than one of the summer fire and smoke from the winter fire spreads farther than one of the summer fire, which are dependent on the direction of air flow into access opening. Evacuation simulation indicated that the required safe evacuation time(RSET) of the summer and winter fires are 262, 670 s each.

• Journal of the Korea Safety Management & Science
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• v.12 no.4
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• pp.53-60
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• 2010

When a fire breaks out, it is difficult to find out the causes of the fire, because combustible things around fire scene are usually burnt away. Among many causes of fires are electronic wires, this thesis deal with the destroyed sheath of electronic wires caused by fire. It was studied with the use of measurement devices focusing on the distinctions of wires and conductors. This study especially emphasized the process of deterioration, burning pattern, and composition of electronic wire conductor. It also has a phenomenological approach to the distinctive cause of fire by some partial force. The fire prevention methods have been suggested through the analysing results of fire patterns. This study is expected to be a useful material for analyzing various electrical fires.

• International Journal of Advanced Culture Technology
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• v.9 no.4
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• pp.424-430
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• 2021

The purpose of this study is to analyse the characteristics and spreading laws of parameters such as fire smoke, concentration of CO, visibility, and temperature at fire scene in high-rise residential buildings under the different conditions of fire doors and automatic fire extinguishing systems. Using Pyrosim to simulate diverse fire scenes in a high-rise apartment with corridors, to analyze the changes in those parameters. The results show that when a fire occurs, closing the fire-fighting corridor will increase the smoke temperature and concentration of CO in the stairwell, and reduce the height and visibility of the smoke layer; the automatic fire extinguishing system effectively suppresses the increase in the temperature of the fire smoke and the sedimentation of the smoke layer. Reasonable setting and operation of the automatic fire extinguishing system could effectively inhibit the spread of fire. Although closing fire corridor can slow down the direct upward spread of smoke through the corridor, it will force the fire smoke into the stairwell, which will seriously affect evacuation through the stairs. Therefore, in order to reduce risks, it is forbidden to close the fire doors of the firefighting corridor and stacking combustible materials in the corridor, Also, intensifying inspections and ensuring the normal operation of the automatic fire extinguishing system are indispensable. Based on the research results, the significance of installing fire-fighting facilities in the construction of high-rise apartments was discussed and proved.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.381-384
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• 2008

The purpose of this study is to evaluate influence factors of secondary traumatic stress, burnout, and physical symptoms which were experienced by fire fighters. The questionnaire research was done for field service fire fighters who work in Korea. I analyzed 358 questionnaires and the questionnaires consisted of stress scale, work force, burden of physical symptoms, and self-control to stress. Through this study I will propose the solution for the posttraumatic stress disorder(PTSD) for the near future.

• Structural Engineering and Mechanics
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• v.32 no.5
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• pp.635-648
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• 2009

This paper describes fire performance of eight axially restrained reinforced concrete (RC) columns under a combination of two different load ratios and two different axial restraint ratios. The eight RC columns were all concentrically loaded and subjected to ISO834 standard fire on all sides. Axial restraints were imposed at the top of the columns to simulate the restraining effect of the rest of the whole frame. The axial restraint was effective when the column was expanding as well as contracting. As the results of the experiments have shown, the stiffness of the axial restraint and load level play an important role in the fire behaviors of both HSC and NSC columns. It is found that (a) the maximum deformations during expanding phase were influenced mostly by load ratio and hardly by axial restraint ratio, (b) For a given load ratio, axial restraint ratio had a great impact on the development of axial deformation during contraction phase beyond the initial equilibrium state, (c) increasing the axial restraint increased the value of restraint force generated in both the NSC and HSC columns, and (d) the development of column axial force during the contracting and cooling phase followed nearly parallel trend for columns under the same load ratio.

• Fire Science and Engineering
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• v.26 no.6
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• pp.57-63
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• 2012

The modern trend for high-rise buildings makes the application of fire protection systems difficult and the current systems have a limitation to provide appropriate functions. Indoor hydrant systems are fire suppression systems installed in most buildings that require valves, hoses, and nozzles to be manually operated in the event of a fire. Therefore, high discharge pressure can cause difficulty in the operation of indoor fire hydrant systems and damage to hoses due to a high reaction force. To prevent these problems, the pressure is reduced and decompression valves are commonly installed at angle valves which are the discharge points of indoor hydrants. In the case of high-rise buildings, however, there are cases where stable operation is difficult even with the installation of decompression valves. To verify this, we have measured the decompression performance by the orifice diameter and calculated the reaction force. Results of the study showed that decompression valves need to be produced in different sizes to provide stable decompression where high pressure is required as in high-rise buildings.