• 대한핵의학회:학술대회논문집
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• 대한핵의학회 2000년도 2nd Korea-China Congress of Nuclear Medicine and 39th Annual Spring Meeting if the Korea SOciety Nuclear Medicine
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• pp.61-61
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• 2000

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2014년도 추계학술대회 논문집
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• pp.178-179
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• 2014

In this study, $Ni-W-Si_3N_4$ alloy composite coatings were prepared by pulse electrodeposition method using nickel sulfate bath with different contents of tungsten source, $Na_2WO_4.2H_2O$, and dispersed $Si_3N_4$ nano particles. The structure and microstructure ofcoatings was separately analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). Results indicated that nano $Si_3N_4$ and W content in alloy had remarkable effect on microstructure, microhardness and scratch resistant properties. Tungsten content in Ni-W and $Ni-W-Si_3N_4$ alloy ranged from 7 to 14 at.%. Scratch test results suggest that as compared to Ni-W only, $Ni-W-Si_3N_4$ prepared from Ni/W molar ratio of 1:1.5 dispersed with 20 g/L $Si_3N_4$ has shown the best result among different samples.

• 한국표면공학회지
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• 제44권2호
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• pp.68-73
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• 2011

A Ni-W thin-film was synthesized by electrodeposition, and its corrosion resistance and electrical surface conductivity were investigated. Amount of tungsten in the Ni-W thin-film increased linearly with current density during the electrodeposition, and crack-free and low-crystalline Ni-21 at.%W coating layer was obtained. Corrosion resistances of the Ni-W thin-films were examined with an anodic polarization method and a storage test in a strong sulfuric acid solution. As a result, the Ni-21 at.%W thin-film exhibited the greatest corrosion resistance, and maintained the electrical surface conductivity even after the severe corrosion test, which could be applicable as a surface treatment for advanced metallic bipolar plates in fuel cell or redox flow battery systems.

• 한국재료학회지
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• 제15권2호
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• pp.85-88
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• 2005

[ $W-15wt.\%$ ] Cu nanocomposite powders are fabricated by ball-milling and subsequent hydrogen-reduction. The compacted parts of $W-15wt.\%Cu$ nanocomposite powders were sintered at $1200^{\circ}C$ for 1 h with various heating rates of 5 and $20^{\circ}C/min$. The homogeneity of the sintered microstructures was evaluated through homogeneity index by the standard deviation of Victor's hardness test. The W-W contiguities were calculated by using Voronoi diagrams. The sintered microstructure with the heating rate of $20^{\circ}C/min$ was more homogeneous and had lower W-W contiguity than that of $5^{\circ}C/min$. The microstructural homogeneity was directly related to the W-W contiguity. Thermal conductivity of the sintered parts with the heating rate of $20^{\circ}C/min$ was higher than that with heating rate of $5^{\circ}C/min$. This phenomenon indicates that the thermal conductivity is affected by the W-W contiguity resulting from the homogeneity of the sintered microstructure.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1265-1266
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• 2013

• 한국화재소방학회논문지
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• 제32권6호
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• pp.28-33
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• 2018

건축물 구획공간에 따른 화재성상 및 열방출율을 측정하기 위하여 실물규모 침대 매트리스의 표준화재시험방법(KS F ISO 12949 : 2011)으로 화재시험을 수행하였다. 개방형공간과 구획공간 모두 버너착화 후 초기 약 3분까지는 유사한 화재성장의 경향을 보이는 것으로 확인되었다. 3분후 구획공간에서의 열방출율이 개방형 공간보다 증가되어 높은 것으로 확인되었다. 침대 매트리스(SS)의 경우, 개방형 공간에서의 최대열방출율은 735 kW이며, 구획공간에서의 최대열방출율은 992 kW 로 측정되었다. 침대 매트리스(Q)의 경우 3분후 구획공간에서의 열방출율이 개방형 공간보다 급격하게 증가되는 것으로 확인되었다. 개방형 공간에서의 최대열방출율은 1,087 kW, 이 때의 측정시간은 346s 이며, 구획공간에서의 최대열방출율은 2,127 kW, 이때의 측정시간은 287 s 측정되어 구획공간에 따른 최대열방출율 및 측정시간의 차이가 확인되었다.

• 한국재료학회지
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• 제26권12호
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• pp.751-756
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• 2016

Graphite was diffusion-bonded by hot-pressing to W-25Re alloy using a Ti interlayer. For the joining, a uniaxial pressure of 25 MPa was applied at $1600^{\circ}C$ for 2 hrs in an argon atmosphere with a heating rate of $10^{\circ}C\;min^{-1}$. The interfacial microstructure and elemental distribution of the W-25Re/Ti/Graphite joints were analyzed by scanning electron microscopy (SEM). Hot-pressed joints appeared to form a stable interlayer without any micro-cracking, pores, or defects. To investigate the high-temperature stability of the W-25Re/Ti/Graphite joint, an oxy-acetylene torch test was conducted for 30 seconds with oxygen and acetylene at a 1.3:1 ratio. Cross-sectional analysis of the joint was performed to compare the thickness of the oxide layer and its chemical composition. The thickness of W-25Re changed from 250 to $20{\mu}m$. In the elemental analysis, a high fraction of rhenium was detected at the surface oxidation layer of W-25Re, while the W-25Re matrix was found to maintain the initial weight ratio. Tungsten was first reacted with oxygen at a torch temperature over $2500^{\circ}C$ to form a tungsten oxide layer on the surface of W-25Re. Then, the remaining rhenium was subsequently reacted with oxygen to form rhenium oxide. The interfacial microstructure of the Ti-containing interlayer was stable after the torch test at a temperature over $2500^{\circ}C$.

• 한국화재소방학회논문지
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• 제26권2호
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• pp.105-111
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• 2012

본 연구에서는 건축외장재로 많이 사용되고 있는 알루미늄복합패널의 일반재와 난연재에 대한 화재성능 비교분석에 관해 연구하였다. 실험방법은 중소형 실험장치 중 콘칼로리미터 실험과 SBI(Single Burning Item)을 적용하여 분석하였다. 그 결과 콘칼로리미터 실험에서 최대 열방출률이 일반 알루미늄복합패널은 $1,293kW/m^2$($75kW/m^2$), 난연 알루미늄복합패널은 $70kW/m^2$($75kW/m^2$)가 측정되었다. SBI 실험에서 화재확산지수가 일반 알루미늄복합패널은 약 743W/s이고 난연 알루미늄복합패널은 약 97 W/s의 값이 측정되었다. 이는 일반 알루미늄복합패널의 경우 건축물 내장재의 성능기준에서 난연기준에도 훨씬 못 미치고, 플래쉬 오버(Flash over) 발생 가능성을 나타내었다. 따라서 이러한 알루미늄복합패널의 화재 위험성을 평가하여 외장재로서 사용 시 갖춰야 할 조건에 대한 기준마련이 시급히 요구된다.

• 한국분말재료학회지
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• 제18권3호
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• pp.226-237
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• 2011

W-ZrC and W-HfC composite powders were fabricated by the Plasma Alloying & Spheroidization (PAS) method and the powders were sprayed into hybrid coating layers by using Low Vacuum Plasma Spray (LVPS) process, respectively. Microstructure, mechanical properties, and ablation characteristics of the fabricated coating layers were investigated. The LVPS process led to successful production of W-Carbide hybrid coatings, approximately 400 ${\mu}M$ or above in thickness. As the substrate preheating temperature increased from $870^{\circ}C$ to $917^{\circ}C$, the hardness of the W-ZrC coating layer increased due to decreased porosity. Vickers hardness showed higher value (about 108.4 HV) in W-ZrC hybrid coating material compared to that of W-HfC while adhesive strength was found to be similar in both coating layers. The plasma torch test revealed good ablation resistance of the W-Carbide hybrid coating layers. The relatively high performance W-ZrC coating layer at the elevated temperature is thought to be attributed to both the strengthening effect of ZrC particle remained in the layer and the formation of ZrO2 phase with high temperature stability.

• Preventive Nutrition and Food Science
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• 제4권3호
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• pp.188-192
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• 1999

To study effects of methanol extract of prosomillet on lopid metabolism , five groups of male Sprang-Dawley rats weighing 116$\pm$9 g were fed test diets for four weeks. The five diets consisted of one low fat(5% w/w) diet containing starch as carbohydrate source(normal) and four high fat diets(15% w/w) containing 40.5%(w/w)sucrose(control) and additional 80% nethanol extractof prosomillet at the levels of 0.3% and 1%(w/w) or prosomillet powder at the level of 20%(w/w). Serum level of total cholesterol was a little higher but that of triglyceride was 41% lower in 20% (w/w) prosomillet powder group than in the control group. The cholesterol levels of two Liver cholesterol levels were lower and phospolipid levels higher in all three prosomillet powder group . Fecal excretionof bile acid was most increased in the prosomillet powder group among all five test groups. Acitivity of liver microsomal 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase was significantly lower in 0.3% methanol extract fed group than the control and also appeared to be reduced in 1% extract fed one, wherease those of 20 cholesterol 7$\alpha$-hydroxylase were not different among the five groups. Activities of liver cytosilic glucose-6-phosphate dehydrogenase(G6PDH) and malic enzyme were decreased in 0.3% prosomillet methanol extract and 20% powder groups. The results indicate that in addition to fiber, certain active components in prosomillet have potential to exert hypolipidemic effects via regulating hepatic cholesterogenesis and lipogenesis.