• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 제35회 춘계학술대회
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• pp.226-234
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• 2002

A systematic study of the role of transfer films on friction properties was performed with various temperatures in the brake system. An NAO friction material specimens containing 9 ingredients were tested using a pad-on-disk type friction tester A new method of measuring the transfer film thickness was developed by considering the electrical resistance of the transfer film using a 4-point probe technique. The properties of transfer film such as surface morphology and film distribution vaied according to the relative amount of graphite and magnesium oxide. By using SEM, it was possible to obtain information about the chemical composition of the transfer film. Results showed that there detected a threshold value of the relative amount of a two active materials to maintain a certiain thickness of a transfer film. Results also showed that formation of friction layer generated on the friction surface was strongly affected by chemical action of two ingredients during sliding due to chemical reaction of solid lubricants at different interface temperature. The results suggested that no apparent relationship between transfer film thickness and the average friction coefficient was founded and friction characteristics were affected more by the property of the solid lubricant and abrasive in the material.

• 한국전기전자재료학회논문지
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• 제14권12호
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• pp.1016-1022
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• 2001

This study presents the microstructure-electrical property relationship of reactive-sputtered Ta$_2$O$_{5}$ MIM capacitor structure processed by annealing in a vacuum and $O_2$ ambience. A microstructural investigation showed the existence of amorphous phase in as-deposited condition and the formation of preferentially oriented-Ta$_2$O$_{5}$ in $700^{\circ}C$ annealing. On annealing under the $O_2$ atmosphere, the Ta$_2$O$_{5}$ film exhibited the trend of its composition\`s approaching to stoichiometry from off-stoichiometry, analyzed by EPMA, the leakage current decrease and the enhanced temperature-capacitance characteristic stability. In the case of low temperature vacuum-annealing treatment, the leakage current behavior was stable irrespective of applied electric field. In the high temperature-annealed film at a vacuum condition, the electrical properties was observed to deteriorate. The results state that in Ta$_2$O$_{5}$ film annealed at $O_2$ atmosphere, gives rise to improvement of electrical characteristics in the capacitor were improved by reducing oxygen-vacancy and dandling Ta-O bond.-O bond.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.39-40
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• 2006

The relationship between the powder particle size change and a mechanical property of the Metal Injection Molding (MIM) product was examined in detail. The XRD results indicate that the diffraction peaks of BCC appeared in compacts of powder particle size of 4 to $10{\mu}m$ as well as the bulk SUS630. However, the diffraction peaks from both BCC and FCC were observed in the compact with powder size less than $3{\mu}m$. TEM observation revealed that the powder with those BCC/FCC two phase structure have a finely dispersed $SiO_2$ precipitates. Because the Si is ferrite stabilizing element, decrease of Si composition in the matrix phase by the $SiO_2$ precipitation resulted in formation of the retained austenite. Therefore, controlling the elements such as Si as well as oxygen decrease is very important to obtain a normal microstructure in ultra-fine powder $(<3{\mu}m)$ injection molding.

• 한국재료학회지
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• 제27권6호
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• pp.307-311
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• 2017

Organometal halide perovskite materials, due to the tunability of their electronic and optical properties by control of composition and structure, have taken a position of significant importance in optoelectronic applications such as photovoltaic and lighting devices. Despite numerous studies on the structure - property relationship, however, practical application of these materials in electronic and optical devices is still limited by their processability during fabrication. Achieving nano-sized perovskite particles embedded in a polymer matrix with high loading density and outstanding photoluminescence performance is challenging. Here, we demonstrate that the careful control of nanoparticle formation and growth in the presence of poly(methyl methacrylate) results in perovskite nanoparticle - polymer nanocomposites with very good dispersion and photoluminescence. Furthermore, this approach is found to prevent further growth of perovskite nanoparticles, and thus results in a more uniform film, which enables fabrication using the perovskite nanoparticles.

• Nuclear Engineering and Technology
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• 제55권6호
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• pp.2147-2157
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• 2023

The aggregate-forming minerals in concrete undergo volume swelling and microstructure change under neutron irradiation, leading to degradation of physical and mechanical properties of the aggregates and concrete. A comprehensive investigation of volume change and elastic property variation of major aggregate-forming minerals is still lacking, so molecular dynamics simulations have been employed in this paper to improve the understanding of the degradation mechanisms. The results demonstrated that the densities of the selected aggregate-forming minerals of similar atomic structure and chemical composition vary in a similar trend with deposited energy due to the similar amorphization mechanism. The elastic tensors of all silicate minerals are almost isotropic after saturated irradiation, while those of irradiated carbonate minerals remain anisotropic. Moreover, the elastic modulus ratio versus density ratio of irradiated minerals is roughly following the density-modulus scaling relationship. These findings could further provide basis for predicting the volume and elastic properties of irradiated concrete aggregates in nuclear facilities.

• 패션비즈니스
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• 제17권6호
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• pp.44-59
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• 2013

The modern people do express their personalities by appearance and actively use the appearance as the social tools, and the attractive appearance largely does influence the human relationship. As the appearance's importance is being magnified, the attractive appearance and favourable impression is an important standard for job performance and social position, and used as the way to reach the social goal. This study does investigate the design's kind and character of the beard which belongs to the male exclusive property and compare the differences of the impression's formation according to the beard design. The empirical results confirmed that the male beard design formated the various impressions according to the designs and their mutual relationship existed. Therefore, the beard is a symbol of maleness and an expression for the social position and personal character, whereas it possesses the very important meaning as the influencing factor on the impression's change. First, the pre stimuli were finished through the pre survey for composition of questionnaire in order to evaluate the impression after selection of experimental models and beard types for measuring instruments. Second, sixty three university students were surveyed by pre stimuli and questionnaire as pre experiment, and afterwards the measuring instruments and experimental design were revised. Third, the stimuli completed (nine beard designs) were intentionally well distributed as questionnaire by sex and ages in Seoul metropolitan and her environment. and the factorial analysis and the coefficient of Cronbach's ${\alpha}$ for reliability test were completed for questionnaire's validity using SPSS/PC+ Window Ver. 12.0.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.208.2-208.2
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• 2016

Many researchers have paid attention to the studies on the interaction between non-thermal plasma and aqueous solutions for biomedical applications. The gas composition in the plasma is very important. Oxygen and nitrogen are the main gases of interest in biological applications. Especially, we focus on the oxygen concentration. In this experiment, we studied the role of oxygen concentration in plasma induced chemical reactions in solution. At first, the amount of ions are measured according to changing the oxygen concentration. And we checked the relationship between these ions and pH value. Secondly, when the oxygen concentration is changed, it identified the type and amount of radical generated by the plasma. In order to confirm the effect of these chemical property change to biological material, hemoglobin and RBCs are chosen. RBCs are one of the common basic biological cells. Thirdly, when plasma treated according to oxygen concentration in nitrogen feeding gas, oxidation of hemoglobin and RBC is checked. Finally, membrane oxidation of RBC is measured to examine the relation between hemoglobin oxidation and membrane damage through relative hemolysis and Young's modulus. Our results suggest that reactive species generated by the plasma differsdepending on the oxygen concentration changes. The pH values are decreased when oxygen concentration increased. OH decrease and NO increase are also observed. These reactive species makes change of chemical properties of solution. We also able to confirm that the difference in these reactive species to affect the oxidation of the Hb and RBCs. The Hb and RBCs are more oxidized with the high oxygen concentration conditions. But membrane is damaged more by plasma treatment with only nitrogen gas. It is shown that red blood cells membrane damage and oxidation of hemoglobin are not directly related.

• 소성∙가공
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• 제8권3호
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• pp.247-247
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• 1999

The segregation (distribution) of nickel and the composition of its constituents influence the low thermal expansion characteristics (Invar effect) in Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy. The change of coefficient of the thermal expansion and magnetic properties were studied as an aspect of carbon addition causing the segregation of Ni in primary austenite of as-cast Fe-30 wt.% Ni-12.5 wt.% Co Invar alloy. The coefficient of thermal expansion of Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy showed its lowest value at 0.08 wt.% carbon, increased with increasing carbon content in the range of 0.08-1.0 wt.%C, kept constant at 1.0-2.0 wt.%C and decreased at carbon higher than 2.0 wt.%. The effective distribution of the coefficient of nickel in as-cast Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy increased with increasing carbon content. The volume fraction of they phase of Fe-30 wt.% Ni-12.5 wt.% Co-xC alloy increased with increasing carbon content. The microstructure of Fe-30 wt.% Ni-12.5 wt.% Co-xC alloy changed with the carbon content was independent of the coefficient of thermal expansion. The Curie temperature changed linearly with the carbon content and was similar to the change of the coefficient of thermal expansion. Moreover, the coefficient of thermal expansion decreased when the ratio of saturation magnetization to Curie temperature ($\sigma_s/T_c$) increased, decreasing the Curie temperature and showed a specific relationship with the magnetic properties of the Fe-30 wt.% Ni-12.5 wt.% Co-xCInvar alloy.

• 한국전기전자재료학회논문지
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• 제15권1호
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• pp.15-23
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• 2002

In this study, metal/ZnO contacts were thermally annealed at different temperatures (as-dep., 400$^{\circ}C$, 600$^{\circ}C$, 800$^{\circ}C$, 1000$^{\circ}C$) for the investigation of electrical properties, and surface and interface characteristics. The analysis of the element composition and the chemical bonding state of the surface was made by the XPS(X-ray photoelectron spectroscopy). An attempt was made to establish the electrical property-microstructure relationship for the (Ti, Au)/ZnO. The Ti/ZnO contact exhibits an ohmic characteristics with a relatively high contact resistance of 4.74${\times}$10$\^$-1/ $\Omega$$\textrm{cm}^2$ after an annealing at 400$^{\circ}C$. The contact showed a schottky characteristics when the samples were annealed at higher temperature than 400$^{\circ}C$. The transition from the ohmic to schottky characteristics was contributed from the formation of the oxide layers as was confirmed by the peaks for O-O and Ti-O bondings in XPS analysis. For the Au/ZnO contact the lowest contact resistance was obtained from the as-deposited sample. The resistance was slowly increased with annealing temperature up to 600$^{\circ}C$. The ohmic characteristics were maintained eden fort 600$^{\circ}C$ annealing. The XPS analysis showed that the Au-O intensity was dramatically decreased with temperature above 600$^{\circ}C$.

• 에너지공학
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• 제28권1호
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• pp.1-9
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• 2019

석탄 화력발전소의 배연탈황공정에서 탈황용 흡수제로 사용하는 석회석을 대상으로 본드의 분쇄일지수(BWI) 및 하드그로브지수(HGI) 측정 후 분쇄효율을 비교하였다. 측정결과, 국내 탈황용 석회석의 분쇄성지수는 HGI가 증가함에 따라 BWI가 감소하는 선형적인 반비례 관계를 확인할 수 있었으며, 석회석의 화학조성 및 채광위치에 따른 결정구조에 따라 분쇄효율의 차이가 발생하였다. 이에 따라, 석회석의 분쇄성을 측정할 경우 측정방법이 까다롭고 시간이 오래 걸리는 BWI 보다 간편하게 측정할 수 있는 HGI를 활용하여도 시료의 분쇄성 차이를 확인할 수 있을 것으로 사료되며, 분쇄 특성에 따른 석회석의 선택적 활용 시 탈황효율 또한 향상시킬 수 있을 것으로 판단된다.