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원자로급 흑연 IG-11의 산화율에 따른 기공도와 열방사율과의 관계
서승국,노재승,김경화,지세환,김응선,Seo, Seung-Kuk,Roh, Jae-Seung,Kim, Gyeong-Hwa,Chi, Se-Hwan,Kim, Eung-Seon 한국재료학회 2008 한국재료학회지 Vol.18 No.12
Graphite for the nuclear reactor is used to the moderator, reflector and supporter in which fuel rod inside of nuclear reactor. Recently, there are many researches has been performed on the various characteristics of nuclear graphite, however most of them are restricted to the structural and the mechanical properties. Therefore we focused on the thermal property of nuclear graphite. This study investigated the thermal emissivity following the oxidation degree of nuclear graphite with IG-11 used as a sample. IG-11 was oxidized to 6% and 11% in air at 5 l/min at $600^{\circ}C$. The porosity and thermal emissivity of the sample were measured using a mercury porosimeter and by an IR method, respectively. The thermal emissivity of an oxidized sample was measured at $100^{\circ}C$, $200^{\circ}C$, $300^{\circ}C$, $400^{\circ}C$ and $500^{\circ}C$. The porosity of the oxidized samples was found to increase as the oxidation degree increased. The thermal emissivity increased as the oxidation degree increased, and the thermal emissivity decreased as the measured temperature increased. It was confirmed that the thermal emissivity of oxidized IG-11 is correlated with the porosity of the sample.
노재승(Jae-Seung Roh),안재상(Jai-Sang Ahn),김범준(Beom-Jun Kim),전호연(Ho-Yeon Jeon),서승국(Seung-Kuk Seo),김석환(Suk Hwan Kim),이상우(Sang-Woo Lee) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.2
This study is the research on the thermal emissivity depending on the bulk graphite’s alignment degree. Bulk graphites were manufactured by uni-axial pressing and subsequent heat treatment of natural graphite flakes with organic binder. The samples were prepared to be 0° (relative to the 002 c-face), 45°, and 90° (relative to the 100 a-face) for measuring alignment degree. The alignment degree of the sample was measured by XRD. The thermal emissivity was measured by infrared thermal image camera at 100oC and compared with the value obtained by Infrared spectroscopy. The alignment degree and thermal emissivity of 0° sample were measured to be 0 and 0.70 respectively. And those of 90° sample were 0.73 and 0.80 respectively. The emissivity value was correlated with obtained by IR spectroscopy. Therefore it was considered that the thermal emissivity of the bulk graphite is correlated with the alignment degree.
논문 : IG-11 원자로용 흑연의 열방사 특성에 미치는 표면 거칠기의 영향
노재승 ( Jae Seung Roh ),서승국 ( Seung Kuk Seo ),김석환 ( Suk Hwan Kim ),지세환 ( Se Hwan Chi ),김응선 ( Eung Seon Kim ),김혜성 ( Hye Sung Kim ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.7
This paper reports the relationship between the surface roughness and thermal emissivity of graphite (IG-11) in nuclear reactors. The roughness was controlled by changing the oxidization time, resulting in 0, 6, and 11% losses of mass. The levels of roughness were 0.40, 0.72 and 1.09㎛ for the weight loss of 0, 6 and 11%, respectively. The binders and graphite fillers were found to have sequentially oxidized with a higher thermal emission for the highly oxidized sample, but with a lower emission when measured at a higher temperature. Our study suggests a method for predicting the thermal emission rate of graphite in a nuclear reactor based on roughness measurement.
엄운용,노재승,안재상,강동수,서승국,김석환,Eom, Woon-Yong,Roh, Jae-Seung,Seo, Seung-Kuk,Ahn, Jai-Sang,Kang, Dong-Su,Kim, Suk-Hwan 한국재료학회 2010 한국재료학회지 Vol.20 No.4
Recent high efficiency electronic devices have been found to have heat emission problems. As for LEDs, an excessive increase in the device temperature causes a drop of the luminous efficiency and circuit lifetime. Therefore, heat release in the limited space of such electronic parts is very important. This is a study of the possibility of using a coating of carbon materials as a solution for the thermal emission problem of electronic devices. Powdered carbon materials, cokes, carbon blacks, amorphous graphite, and natural flakes were coated with an organic binder on an aluminum sheet and the subsequent thermal emissivity was measured with an FT-IR spectrometer and was found to be in the range of $5{\sim}20\;{\mu}m$ at $50^{\circ}C$. The emissivity of the carbon materials coated on the aluminum sheet was shown to be over 0.8 and varied according to carbon type. The maximum thermal emissivity on the carbon black coated-aluminum surface was shown to be 0.877. The emissivity of the anodized aluminum sheets that were used as heat releasing materials of the electronic parts was reported to be in the range of 0.7~0.8. Therefore, the use of a coating of carbon material can be a potential solution that facillitates heat dissipation for electronic parts.