• Journal of Conservation Science
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• v.27 no.3
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• pp.323-332
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• 2011

Microtexture and components of 7 glass bead fragments excavated from Andong tumulus in Gildu-ri, Goheung have been analyzed to determine the characteristics of their weathered condition as well as chemical compositions. Firstly, status of microtexture shows that there is a large quantity of pollutants which were presumably transferred from the buried environment into the surface and the gap of the cracks. The examination has displayed that there are less amount of alkali metal components such as sodium (Na) and potasium (K) in the gap of the cracks than on the surface. The chemical compositions analysis has confirmed that two samples belongs to potash glass group ($K_2O-SiO_2$), four to soda glass group ($Na_2O-SiO_2$), and one to the mixed alkali glass group. Chromophoric elements of the glass varies by different colours: blue and navy are cobalt (Co); greenish blue is copper (Cu) and iron (Fe); and light brown is Fe respectively. Such kind of scientific analysis of the excavated glass beads will contribute to the understanding of interchange between various local cultures and arts within the southwest region of Korean Peninsula during the 4th and the 5th centuries.

• KSBB Journal
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• v.16 no.3
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• pp.295-301
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• 2001

The leaching effect of Thiobacillus ferrooxidance (ATCC 19859) upon polished pyrite ore in 9K medium at $30^{circ}C$ for 30 days was investigated. The surface atomic ratios for Fe, S, Al, Si, and Cu were analyzed by EPMA using fresh and leached samples. The atomic ratio of Fe and S were changed to Fe rich phase as leaching progressed over 13 days but the Fe/S ratio became constant between 13 and 30 days. SEM imaging showed that $10\mum$ oblong shapes formed on the surface after 13 days and that these further developed until 23 days. Fe, S and K atomic ratios were analyzed by SEM-EDS.

• Journal of the Korean Vacuum Society
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• v.6 no.S1
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• pp.110-114
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• 1997

Development of metal ion source growth of high quality Cu metal film formation of non-stoichiometric $SnO_2$ films of Si(100), and modification fo polymer surface by low enregy ion beam have been carried out at KIST Ion Beam Lab. A new metal ion source with high ion beam flux has been developed by a hybrid ion beam (HIB) deposition and non-stoichiometric $SnO_2$ films are controlled by supplying energy. The ion assisted reaction (IAR) in which keV ion beam is irradiated in reactive gas environment has been deveolped for modifying the polymers and enhancing adhesion to other materials and advantages of the IAR have been reviewed.

• Journal of Conservation Science
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• v.3 no.1 s.3
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• pp.13-18
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• 1994

Chemical analysis and metallographic observations of the iron slag were carried out in an attempt to estimate the old iron-making process. The slag containing $9.3\%\;TiO_2$ without Cu indicates that the ore used for smelting was sand iron, not rock ore. The phases identified in the slag were $ulv\ddot{o}spinel$, magnetite, $w\ddot{u}stite$, fayalite etc. This also supports the fact that the smelted ore was iron sand. The total amount of Fe and slag-making components$(=SiO_2+Al_2O_3+MgO+CaO)$ were $40.7\%\;and\;36.1\%$, respectively. These values were average ones found in the old slags formed in the ancient iron-making process. Assuming that $TiO_2$ in the ore combines with FeO, resulting in the formation of $ulv\ddot{o}spinel$, the estimated temperature of smelting was found to be about $1200^{\circ}C$.

• Journal of Welding and Joining
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• v.34 no.5
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• pp.77-82
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• 2016

In this study, Microstructure and hardness of 1st layer with crystallographic orientation were investigated about solidification structure in multipass weld using high Mn-Ni flux cored wire. Microstructure of solidification consisted of austenite matrix and a little ${\varepsilon}-phase$ in grain boundaries. Orientation of grains was usually (001), (101), (111). According to crystallographic orientation, morphology of primary dendrite was different. The depletion of Fe and the segregation of Mn, C, Ni, Si, Cu, Cr, O were found along the grain boundaries. The area of segregation was wide with an order of (001), (101), (111) grains. And hardness of grains with crystallographic orientation increased with an order of (001), (101), (111) grains because of the segregation along dendrite boundary.

• Journal of the Korean Magnetics Society
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• v.3 no.3
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• pp.190-195
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• 1993

새로운 Fe기 초미세 결정립합금의 제조 가능성 및 자기특성에 관하여 조사하였다. 고포화자화 (Fe.$_{85}$Co.$_{15}$ )$_{80}$B$_{20}$ 비정질합금에서 천이금속을 약 10 at.% Al으로 치환한 (Fe.$_{85}$ Co.$_{15}$ )$_{70}$B$_{20}$Al$_{10}$ 합금은 급속응고에 의하여 비정질 기지내에 직접 .alpha. -Fe(Co)의 석출이 가능하다. 또한 (Fe.$_{85}$Co.$_{15}$ )$_{70}$B$_{20}$Al$_{10}$합금에 2~6 at.% Nb의 첨가는 급속 응고시 결정립성장을 억제하고 포화자왜를 약 6ppm이하로 감소시켜 자기 특성을 개선시킨다. 열처리에 의한 자기 특성은 Nb의 치환량이 증가할 수록 감소한다. 400 .deg. C에서 1시간 열처리한 (Fe.$_{85}$Co.$_{15}$ )$_{70}$ B$_{18}$ Al$_{10}$Nb$_{2}$합금은 평균 약 8nm이하의 .alpha. -Fe(Co) 결정립으로 구성된 초미세 결정립합금 으로 제조가 가능하며, 포화자속밀도, 철손 및 투자율 (f=50 kHz, B$_{m}$ =0.2 T)이 각각 1.2 T, 12W/kg 및 2.5 *$10^{4}$으로 가장 우수하다. 이는 Fe-Si-B-Nb-Cu 초미세결정립합금 및 영자왜 Co기 비정질합금과 거의 같은 자기특성을 나타낸다.다..다.다..낸다.다..

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.88-89
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• 2003

During the past decade, giant magnetotransport phenomena such as giant magetoresistance (GMR) in thin films and in manganese perovskites, and, giant magnetoimpedance (GMI) in soft magnetic amorphous ribbons, have brought much interest in the basic physical understanding and their applications as magnetic recording heads and in magnetic sensors technology. Among the parameters required for the quality of a magnetic sensor, temperature dependences of GMR and GMI profiles are playing an important role. In the present work, we have studied temperature dependences of the longitudinal permeability and giant magnetoimpedance effect in $Co_{70}$F $e_{5}$S $i_{15}$ N $b_{2.2}$C $u_{0.8}$ $B_{7}$ amorphous ribbons expecting as a promising candidate in the domain of magnetic sensors.rs.rs.rs.s.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.173-173
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• 2011

반도체 집적도의 비약적인 발전으로 복잡하고 다양한 공정이 연구되었고 공정 중 박막에서 발생되는 물리적, 화학적 반응들에 대한 연구 필요성이 대두 되었다. 박막은 다양한 공정 환경에서 박막의 특성을 잃지 않고 물성을 유지하여야 한다. 특히 공정상의 고온 환경에서 박막은 안정해야하며 물리적손상이 있어서는 안 된다. 이 논문에서는 반도체의 기판으로 사용되는 Si기판과 금속배선 물질인 Cu와의 확산을 효과적으로 방지하기 위한 W-C-N 확산방지막을 제시하였고 시료 증착을 위하여 rf magnetron sputter를 사용하여 동일한 증착조건에서 질소(N)의 비율을 다르게 하여 박막 내 질소비율(0 sccm, 2 sccm)에 따른 확산방지막을 제작하였다. 이후 시료의 열적 안정성 측정을 위하여 상온, 600도, 800도로 각각 질소 분위기에서 30분간 열처리 과정을 실시하여 열적 손상을 인가하였다. 이후 Nanoindentation기법을 이용하여 총 16 point 측정을 하였다. 이를 Weibull distribution으로 분석하여 정량화 시켜 박막의 균일도와 신뢰도를 연구하였다. 또 WET-SPM을 이용하여 AFM 표면 이미지를 확인하였다. 그 결과 고온에서 박막이 Compressive stress를 받아 박막이 일어남을 확인 하였다. 이는 질화물질이 고온에서 물성변화가 적게 나타나는 것을 알 수 있었고, 균일도와 결정성 또한 질화물질에서 더 안정적이었다.

• Journal of Powder Materials
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• v.14 no.5
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• pp.303-308
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• 2007

The oxidation of $Fe_{73}Si_{16}B_7Nb_3Cu_1$ nanocrystalline powder has been conducted to investigate its influence on the electromagnetic wave absorption characteristics of the soft magnetic material. Oxidation occurred primarily on the surface of nanocrystals. Oxidation reduced the real part of complex permeability due to the reduction of the relative volume of the powder, which otherwise contributes to the permeability. Oxidation reduced the absorption efficiency of the sheet at frequencies over 1GHz, indicating that the relative contribution of skin depth increments to the absorption was not significant. The pulverization and milling process lowered the optimum crystallization temperature of the material by $40{\sim}50^{\circ}C$ because of the internal energy accumulated during the fragmentation and powder thinning processes.

• Journal of Korea Foundry Society
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• v.20 no.1
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• pp.38-45
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• 2000

The remelting for recycling or thin aluminum scrap, such as aluminum chip generally involves melting of these pieces submerged in molten salt flux. In this study, the effects of salt flux compositions and alloying elements on the aluminum dropletscoalescence and oxide film removal were studied in 99.8%Al, Al-1.01%Cu, Al-1.03%Si, and Al-1.38%Mg alloys as a function of holding time at $740^{\circ}C$ Salt fluxes based on NaCl-KCl(1:1) with addition of 5wt.% fluorides(NaF, $Na_3AlF_6$, $CaF_2$) or 5 wt.% chloride($MgCl_2$, $AlCl_3$) were used. The experimental results show that NaCl-KCl(1:1) with addition of 5 wt.% fluorides exhibits better coalescence ability than that with chlorides. The oxide film is not removed by NaCl-KCl(1:1) with addition of 5 wt.%chlorides, while it is removed by NaCl-KCl(1:1) with addition of 5 wt.% fluorides. The aluminum droplets coalescence and oxide film removal by salt fluxes are related to interfacial tension tension between metal and salt flux.