• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.644-655
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• 2023

Purpose: Metal fires occur in metal handling, processing, waste storage plants, etc. It is difficult for firefighters to extinguish metal fires, and it takes a long time, so caution is needed in fire suppression. Method: In this study, current statistics and problems of metal fires were introduced, and then the effectiveness was verified by experiments with using fire extinguishing agents used in Korea. Comparative suppression experiments of 5 different fire extinguishing agents for burning powders of 99.9% magnesium over 150 ㎛ were performed following the metal powder type test method of Class D fire in ISO 7165. Result: 5 fire extinguishing agents are the power types of dry sands and expanded vermiculites most commonly used in Korea, the certified class D fire extinguisher used abroad, and ochers requiring verification, and the liquid silica gel. Conclusion: The results of experiments showed expanded vermiculites were the best metal fire extinguishing agent considering effectiveness, convenience of use, and economical feasibility.

• The Academic Congress of Korean Shoulder and Elbow Society
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• 1999.03a
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• pp.69-69
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• 1999

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1796_1797
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• 2009

원자력발전소의 금속파편감시설비는 원자로냉각 재계통에서 발생되는 충격신호에 대한 정보를 운영자에게 제공하여, 금속이물질로 인한 관련 구조물 파손을 미연에 방지하기 위한 설비이다. 운전 중에 발생되는 충격신호 중 대부분을 차지하는 거짓경보는 열팽창이나 구조물마찰에 의한 신호이나, 국내외에 설치되어 운전 중인 금속파편감시설비에는 열팽창과 구조물마찰에 의한 충격신호를 판단할 수 있는 알고리즘이 탑재되어 있지 않다. 따라서 본 연구에서는 대부분의 거짓 경보를 발생시키는 열팽창 및 구조물마찰에 의한 충격신호를 신호 검출단계에서 배제할 수 있는 알고리즘을 제시하고자 한다.

• Journal of Korea Ship Safrty Technology Authority
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• s.28
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• pp.4-18
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• 2010

자연 현상중의 하나인 낙뢰는 대기중에서 일어나는 뇌운과 보호대상 물체간의 방전현상으로 그 발생 빈도와 피해를 예측할 수 없으며, 국내에서 선박이 낙뢰로 인한 피해가 보고된 경우는 거의 없는 실정이지만 매년 정보화 통신장비 등의 보급확대와 더불어 낙뢰에 의한 피해가 증가할 것으로 판단되며 국내 대부분의 소형선박들은 낙뢰에 취약한 비금속 재질인 FRP선 또는 목선으로 건조되어 있어 낙뢰에 의한 사고에 취약한 현실이다. 본 연구는 근래에 무선설비 항해용구 등의 선박에 초소형의 집적회로를 사용하는 전자장비의 보급이 증대됨에 따라 낙뢰가 선박에 입사하였더라도 부적절한 피뢰설비 때문에 과도전압이 발생하여 제어 감시설비 등을 파손시키는 직 간접적인 피해를 감소시키기 위해서 비금속제 소형 선박에 적합한 피뢰시스템을 제시하여 낙뢰에 의한 피해의 최소화를 위한 대책 마련을 목적으로 수행하였다. KS, ISO, NFPA 및 각 국의 피뢰설비기준에서는 비금속제 선박의 피뢰설비 규정을 제시하고 있으나 국내 규정에서는 비금속제 소형선박에 관한 피뢰설비의 설치기준이 마련되어 있지 않은 실정이므로 이번 연구결과를 통해서 비금속제 소형 선박의 피뢰설비에 대한 합리적인 피뢰설비 설치기준을 설정하는 자료로 활용할 수 있을 것이다.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.697-704
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• 2021

It is hard to get Filaments which are materials of the 3D printing Fused Deposition Modeling(FDM) method as radiation shielding in Korea. and also related research is insufficient. This study aims to provide basic data for the development of radiation shields using 3D printing by evaluating the physical properties and radiation shielding capabilities of filaments containing metal particles. after selecting five metal filaments containing metal particle reinforcement materials, the radiation shielding rate was calculated according to the Korean Industrial Standard's protective equipment test method to evaluate physical properties such as tensile strength, density, X-ray Diffraction(XRD), and weight measurement using ASTM's evaluation method. In the tensile strength evaluation, PLA + SS was the highest, ABS + W was the lowest, and ABS + W is 3.13 g/cm³ which value was the highest among the composite filaments in the density evaluation. As a result of the XRD, it may be confirmed that the XRD peak pattern of the particles on the surface of the specimen coincides with the pattern of each particle reinforcing material powder metal, and thus it was confirmed that the printed specimen contained powder metal. The shielding effect for each 3D printed composite filament was found to have a high shielding rate in proportion to the effective atomic number and density in the order of ABS + W, ABS + Bi, PLA+SS, PLA + Cu, and PLA + Al. In this study, it was confirmed that the metal particle composite filament containing metal powder as a reinforcing material has radiation shielding ability, and the possibility of using a radiation shielding filament in the future.

• Journal of the Korean Society for Nondestructive Testing
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• v.12 no.2
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• pp.21-29
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• 1992

Acceleration signal characteristics of a steel plate, impacted by steel balls, were studied in an attempt to apply the experimental results to the impact location and mass estimation of metallic loose parts in the cooling system of nuclear power plants. Experimental results show that the variation of maximum acceleration amplitude and impact contact time due to the change of ball mass and impact velocity can be well explained by the Hertz impact theory. The frequency spectral pattern shifted slightly in spite of the increase of impact velocity and impact location. Ball mass, however, strongly affected the frequency spectral pattern. Hence the frequency spectrum can be used for estimation of the mass of unknown loose parts in the cooling system.

• Journal of the Korean Society of Radiology
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• v.17 no.1
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• pp.25-30
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• 2023

As 3D printing technology is used in the medical field, interest in metal materials is increasing. The Department of Radiation Oncology uses a shielding block to shield the patient's normal tissue from unnecessary exposure during electron beam therapy. However, problems such as handling of heavy metal materials such as lead and cadmium, reproducibility according to skill level and uncertainty of arrangement have been reported. In this study, candidate materials that can be used for metal 3D printing are selected, and the physical properties and radiation dose of each material are analyzed to develop a customized shielding block that can be used in electron beam therapy. As candidate materials, aluminum alloy (d = 2.68 g/cm³), titanium alloy (d = 4.42 g/cm³), and cobalt chromium alloy (d = 8.3 g/cm³) were selected. The thickness of the 95% shielding rate point was derived using the Monte Carlo Simulation with the irradiation surface and 6, 9, 12, and 16 energies. As a result of the simulation, among the metal 3D printing materials, cobalt chromium alloy (d = 8.3 g/cm³) was similar to the existing shielding block (d = 9.4 g/cm³) in shielding thickness for each energy. In a follow-on study, it is necessary to evaluate the usefulness in clinical practice using customized shielding blocks made by metal 3D printing and to verify experiments through various radiation treatment plan conditions.

• Elastomers and Composites
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• v.37 no.3
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• pp.170-176
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• 2002

Effects of type and loading level of process aids on the rheological and mechanical properties of styrene-butadiene rubber (SBR) compound were investigated. Five commercial grades of process aids composed of fatty acids and their various derivatives such as metal salts, esters, alcohols and amides were selected. The reduction in Mooney and shear viscosities was higher for metal salt-type process aids but lower for the process aids containing high molecular weight fatty acid alcohols and esters with increasing the loading of process aids. Tensile modulus generally decreased, while heat-build-up increased with increased process aids content. No considerable effect was observed for ulimate properties such as tensile strength and elongation at break.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1163-1169
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• 2012

Rubber, a hyperelastic material, is the main material used in tires. During the operation of a car, the tire receives various types of loads. The accumulation of strain energy due to such loads induces tire failure. Generally, because rubber materials used for tires have stress softening characteristics, unlike metals, test methods used for metals cannot be applied to rubber. Therefore, in this study, for the evaluation of the fatigue properties of two types of specimens that have different material components, a tensile test and a fatigue test according to the extended strain range dissimilar to ASTM D4482 are performed, and fatigue life equations are proposed based on the test results.

• Elastomers and Composites
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• v.48 no.2
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• pp.114-124
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• 2013

To study the effects of structural difference and fatty acid chain length of glyceride, new dispersion agents having various glyceride structures such as mono-, di-, and tri-, were prepared using glycerol extracted from palm oil and fatty acid having various chain length ranges from 12 to 18. These dispersion agents were mixed with the rubber compounds and compared with conventional metal salt dispersion agents. Glyceride dispersion agent provided remarkable improvement in silica dispersion, compared to metal salt fatty acidic one, even though the viscosity of mixtures was relatively high due to low lubricating effect, and this was approved by mechanical properties, wear properties, and Payne effect. Also, the longer in chain length of fatty acid and the smaller in numbers of fatty acid, the dispersity of silica was improved.