• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.84-96
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• 2022

In the worst case, a temporary ignition source (also known as transient combustibles) between two electrical panels can damage both panels. Mitigation strategies for electrical panel fires were previously developed using fire modeling and risk analysis. However, since they do not comply with deterministic fire protection requirements, it is necessary to analyze the boundary values at which combustibles may damage targets depending on various factors. In the present study, a sensitivity analysis of input variables related to the damage threshold of two electrical panels was performed for dimensionless geometry using a Fire Dynamics Simulator (FDS). A new methodology using a damage evaluation map was developed to assess the damage of the electrical panel. The input variables were the distance between the electrical panels, the vertical height of the fuel, the size of the fire, the wind speed and the wind direction. The heat flux was determined to increase as the vertical distance between the fuel and the panel decreased, and the largest heat flux was predicted when the vertical separation distance divided by one half flame length was 0.3-0.5. As the distance between the panels increases, the heat flux decreases according to the power law, and damage can be avoided when the distance between the fuel and the panel is twice the length of the panel. When the wind direction is east and south, to avoid damage to the electrical panel the distance must be increased by 1.5 times compared to no wind. The present scale model can be applied to any configuration where combustibles are located between two electrical panels, and can provide useful guidance for the design of redundant electrical panels.

• Journal of the Korean Society of Safety
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• v.15 no.2
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• pp.31-35
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• 2000

After constructing master model utilizing CAD data originated by sketch, product NC data for polyurethane foam using digitized master model data. And model cutting is performed utilizing specially developed polyurethane foam cutting tool in machining center. In this study, it is discussed to construct concept of tool offset, method of tool offset and feature tolerance, etc., that is impossible for cutting of the polyurethane foam by CNC machine.

• Journal of the Korea Safety Management & Science
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• v.21 no.4
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• pp.45-49
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• 2019

The basalt fiber is expected to become a trend for industrial fibers as they have better properties of heat-resistant, non-combustion, absorbent, soundproof, moistureproof, lightweight, corrosion resistant, and high strength properties. Also, the fiber is found to be non-toxic and harmless to the human body. Therefore, in this study, we analyzed the chemical and mineral compositions of powdered sludge of basalt produced at seven sites on Jeju Island for the development of fire resistance insulating material for a building. The results showed that the basalt stone sludge is made from only sodium calcium aluminum silicate and ferridioside components unlike the basalt rock.

• Journal of the Korean Society of Visualization
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• v.21 no.1
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• pp.67-73
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• 2023

In the study, pool boing critical heat flux (CHF) was experimentally investigated depending on the length of heaters. A smooth silicon oxide surfaces are used as the boiling surfaces. As the results of pool boiling experiments based on distilled water in ambient pressure condition, the CHF decreased as the length of the heater increased. By the high speed imaging, it was shown that the number of vapor columns increased as the length of the heater increased. Comparing the number of vapor columns and the CHF according to the heater length, the change in the CHF according to the heater length was analyzed based on the hydrodynamic instability.

• Journal of the Korea Institute of Building Construction
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• v.10 no.5
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• pp.129-135
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• 2010

The purpose of this research is to secure fundamental data on the application of fibre as a fire resistance method for more than 60 MPa high-strength concrete through an examination of mechanical properties and fire resistance performance. The results are as follows: 1) When there are less than 0.5~1.0kg/$m^3$ contents of PP and NY fibre for 60MPa and less high strength concrete, 1.0kg/$m^3$ contents of PP and NY fibre for less than 80MPa high strength concrete and 1.5kg/$m^3$ contents of NY fibre for more than 80MPa high strength concrete, the effect of fibre contents on workability and strength development is not significant. 2) Based on the result of a 3-hour fire resistance test for mock-up column, it is necessary to secure 50 mm of covering depth for the regulation of fire resistance performance of high strength concrete to the standards of The Ministry of Land, Transport and Maritime Affairs. 3) It is necessary to secure more than 400mm of column size for stable fire resistance performance.

• Fire Science and Engineering
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• v.28 no.2
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• pp.76-81
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• 2014

Structural stability of structural beams at high temperature had been evaluated though a horizontal furnace and a standard fire curve. If a structural method and a material are satisfied with the fire test, those are seemed to be guaranteed the safety of residences, fire services men, and properties of the buildings. However, that requires not only longer period but higher cost for making and testing of each structural element. That restrained from developing new methods and new fire protective materials. In this study, an analytic method was executed to demonstrate whether the analytic method using mechanical properties of structural steel at high temperature with heat transfer theory works is working. In this paper, the surface temperature rising and variance of structural stability of a simple H-section beam with a standard fire curve were evaluated and structural stabilities of H-section beam according to differences from length of beam were suggested.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.724-727
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• 2005

Material selection is one of the important activities in design and manufacturing. A selected material at the conceptual design stage affects material properties of the designed part as well as manufacturability and cost of the final product. Unfortunately there are not many accessible material databases that can be used for design. In this research, a web-based material database was constructed. In order to assist designers to compare different materials, two-dimensional and three-dimensional graphs were provided. Using these graphical tools, multi-dimensional comparison was available in more intuitive manner. To provide environmental safety of materials, the database included National Fire Protection Association publication Standard No.704. The web-based tool is available at http://fab.snu.ac.kr/matdb.

• Fire Science and Engineering
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• v.27 no.2
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• pp.40-45
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• 2013

In recent years, many electrical fires have occurred due to complex causes. Therefore, products are required to make with scientific design considering electrical, thermal, mechanical and environmental influences. Disasters can cause losses of life and property with fall in confidence of countries and companies. And demands for safe product have been increased by reason of recent deregulation followed by limitless competition. It is necessary to design safe product in order to improve corporate image and strengthen international competitive power. This paper addresses electrical fire case of air conditioner. The use of air conditioner have recently increased as a result of global warming. The aim of this study is to provide safety design and fire prevention measures of air conditioner through cause analysis and reappearance experiments.

• International Journal of Automotive Technology
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• v.6 no.5
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• pp.501-506
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• 2005

With the respective collapse characteristics of aluminum and CFRP (Carbon Fiber Reinforced Plastics) tubes in mind, axial collapse tests were performed for aluminum/CFRP compound tubes, which are composed of square or circular shaped aluminum tubes wrapped with CFRP outside. In this study, the collapse modes and the energy absorption characteristics were analyzed for aluminum/CFRP compound tubes which have different fiber orientation angle of CFRP. Fracture modes in the aluminum/CFRP compound tubes were rather stable than those in the CFRP tubes alone, probably due to the ductile nature of the inner aluminum tubes. The absorbed energy per unit volume of the aluminum or the aluminum/CFRP compound tubes was higher than that of CFRP tubes. Meanwhile, the absorbed energy per unit mass, for the light-weight design aspect was higher in the aluminum/CFRP compound tubes than in the aluminum tubes or the CFRP tubes. The energy absorption turned out to be higher in circular tubes than in square tubes. Beside the collapse modes and the energy absorption characteristics were influenced by the orientation angle, and the compound tubes took the most effective energy absorption when the fiber orientation angle of CFRP was 90 degrees.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.36-41
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• 2012

Electrical Connections often cause fires due to poor contact. Occurrence rate of these fires tends to increase annually. The reason why poor contacts occur is often because it is the low mechanical pressure at the contact points. A typical connection method using mechanical pressure is a screw terminal type. This study reviewed these poor contact cases in the screw terminals. In order to get reproduction of such cases, two types of experiments were conducted. the first one was conducted under the normal contact condition, and the other one was conducted under the poor contact condition that screw terminal of breaker was loosen and did not meet the requirements of toque value. In both types of experiments, compulsory vibration was adopted as a variable to aggravate poor contacts. Each of various current values(4.5A, 9.0A, 13.5A) is input. In these experiments, relationships of a contact, electrical signal such as current and electric pulse by ZCT and thermal characteristics according to vibration effect are analyzed. The suggested data and results in this study provide the useful resources helping to investigate fires due to poor contact, and they develop the detector for poor contact and finally reduce the electrical fire occurrence rate.