• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.1061-1062
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• 2012

• 한국분무공학회지
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• 제16권2호
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• pp.82-89
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• 2011

When pipe components made of carbon steel in nuclear, fossil, and industry plants are exposed to flowing fluid, wall thinning caused by FAC(flow accelerated corrosion) can be generated and eventually ruptured at the position of pressure boundary. The aim of this study is to identify the locations at which local wall thinning occurs and to determine the turbulence coefficient related to local wall thinning. Experiment and numerical analyses for the tee sections of down scaled piping components were performed and the results were compared. In particular, flow visualization experiment which was used alkali metallic salt was performed to find actual location of local wall thinning inside tee components. In order to determine the relationship between turbulence coefficients and local wall thinning, numerical analyses were performed for tee components in the main feedwater systems. The turbulence coefficients based on the numerical analyses were compared with the local wall thinning based on the measured data. From the comparison of the results, the vertical flow velocity component(Vr) flowing to the wall after separating in the wall due to the geometrical configuration and colliding with the wall directly at an angle of some degree was analogous to the configuration of local wall thinning.

• 설비공학논문집
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• 제23권7호
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• pp.483-491
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• 2011

When pipe components made of carbon steel in nuclear, fossil, and industry are exposed to flowing fluid, wall thinning caused by FAC(flow accelerated corrosion) can be generated and eventually ruptured at the portion of pressure boundary. A study to identify the locations generating local wall thinning and to disclose turbulence coefficient related to the local wall thinning was performed. Experiment and numerical analyses for tee of down scaled piping components were performed and the results were compared. In particular, flow visualization experiment which was used alkali metallic salt was performed to find actual location of local wall thinning inside tee components. To disclose the relationship between turbulence coefficients and local wall thinning, numerical analyses were performed for tee components. The turbulence coefficients based on the numerical analyses were compared with the local wall thinning based on the measured data. From the comparison of the results, the vertical flow velocity component(Vr) flowing to the wall after separating in the wall due to the geometrical configuration and colliding with the wall directly at an angle of some degree was analogous to the configuration of local wall thinning.

• 대한화학회지
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• 제48권5호
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• pp.504-509
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• 2004

구리 금속 분말과 혼합 알칼리금속 다셀레늄화물 용융염 ($KNaSe_x$) 과의 반응을 통하여 판상형태의 결정을 갖는 $KCu_4Se_3$ 화합물을 얻었다. $KCu_4Se_3$화합물의 구조는 X-선 단결정 회절법에의해 결정되었으며 사반면상을 갖는다. (P4/mmm, a=4.013(1)${\AA}$, c=9.712(1)${\AA}$, z=1, R=6.7%). 그 구조는 안티 PbO 구조를 갖는 $Cu_2Se_2$ 층이 겹쳐짐으로서 만들어지는 $[Cu_4Se_3]_n^{n-}$의 이중층으로 구성되어있다. $KCu_4Se_3$의 단결정에 대한 온도 변화에 따른 저항 측정을 통하여 전도체의 특성을 확인하였으며 300 K에서 $1.8{\times}10^{-4}{\Omega}{\cdot}cm$과 20 K에서 $1.0{\times}10^{-6}{\Omega}{\cdot}cm$의 저항 값을 갖는다.

• 설비공학논문집
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• 제25권7호
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• pp.377-385
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• 2013

In this study, the performance of an impeller according to blade length and pitch angle was studied experimentally by building a variable pitch impeller while changing blade length to review the effect of blade length and pitch angle on a fan's performance. The pitch angle was changed in six steps from $20^{\circ}{\sim}45^{\circ}$ at intervals of $5^{\circ}$ while the blade lengths were changed to 90 mm, 100 mm, 110 mm and 120 mm with an identical airfoil shape while carrying out the experiment. The results are summarized as follows : The air flow per static pressure of axial fans increased linearly with increase of pitch angle, but the high static pressure showed a decrease at a pitch angle of $35^{\circ}$. The shaft power increased proportionally to the pitch angle at all blade lengths; the larger the pitch angle, the larger the measured increase of shaft power. This is because the drag at the fan's front increases with the pitch angle. In the axial fans considered in this research, the flow and incre.