• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.160-161
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• 2005

The $(Sr_{1-x}Ca_x)TiO_3$(SCT) thin films are deposited on Pt-coated electrode (Pt/TiN/$SiO_2$/Si) using RF sputtering method with substitutional contents of Ca. The optimum conditions of RF power and $Ar/O_2$ ratio were 140[W] and 80/20, respectively. Deposition rate of SCT thin film was about 18.75$[{\AA}/min]$. The dielectric constant was increased with increasing the substitutional contents of Ca, while it was decreased if the substitutional contents of Ca exceeded over 15[mol%]. All SCT thin films used in this study show the phenomena of dielectric relaxation with the increase of frequency, and the relaxation frequency is observed above 200[kHz].

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.321-324
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• 2005

The main purpose of the present study has been placed on investigating the effects of controlled rolling and cooling on the microstructures and mechanical properties of C-Si-Mn-V steels for cold forming. The steels were manufactured in vacuum induction melting(VIM) furnace and casted to 1.1ton Ingots and the ingots were forged to $\Box150$ billet. The forged billets were reheated in walking beam furnace and rolled to coil, the stocks were rolled by Controlled Rolling and Cooling Technology (CRCT), so rolled at low temperature by water spraying applied in rolling stage and acceleratly cooled before coiling. Rolled coils were cold drawed to the degree of $27\%$ of area reduction without heat treatment. Microstructual observation, tensile test, compression test and charpy impact tests were conducted. The mechanical properties of the steels were changed by area reduction of cold drawing and it is founded that there are optimum level of cold drawing to minimize compression stress for these steels. From the result of this study, it is conformed that mechanical properties and microstructure of C-Si-Mn-V steels for cold forming were enhanced by accelerated cooling and founded optimum level of cold drawing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.718-721
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• 2004

The $(Sr_{0.9}Ca_{0.1})TiO_3$(SCT) thin films are deposited on Pt-coated electrode$(Pt/TiN/SiO_2/Si)$ using RF sputtering method at various substrate temperature. The optimum conditions of RF power and $Ar/O_2$ ratio were 140[W] and 80/20, respectively. Deposition rate of SCT thin films was about $18.75[{\AA}/min]$. The crystallinity of SCT thin films were increased with increase of substrate temperature in the temperature range of $100\sim500[^{\circ}C]$. The dielectric constant of SCT thin films were increased with the increase of substrate temperature, and changed almost linearly in temperature ranges of $-80\sim+190[^{\circ}C]$. The current-voltage characteristics of SCT thin films showed the increasing leakage current as the substrate temperature increases.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.368-375
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• 2005

Batch cultures were carried out to optimize the exo-polysaccharide production by liquid cultures of Pleurotus ferulae. Among the various carbon sources, when $5\%$ of glucose was used, the maximum mycelial growth and exo-polysaccharide concentration reached were 8.78 g/l and 3.59 g/l, respectively. Yeast extract and polypeptone were identified as the most suitable nitrogen sources. In particular, when a mixture of $1\%$ of polypeptone and $0.8\%$ of yeast extract was used, 9.52 g/l of mycelial growth and 4.09 g/l of exo-polysaccharide were obtained. In the case of mineral sources, K$_2$HPO$_4$ and MgSO$_4$$\codt$7H$_2$0 were found to be the best mineral sources for mycelial growth and exo-polysaccharide production. Under the optimized culture conditions, the agitation speed and aeration were investigated for mycelial growth and exo­polysaccharide production in a jar fermentor. The maximum mycelial growth and exo-polysaccharide concentration at 1.5 vvm and 200 rpm obtained were 13.2 g/l and 4.95 g/l, respectively, after 10 days of culture, which were $76\%$ and $79\%$ higher than those of the basal medium. The specific growth rate was decreased with the increase of mycelial growth. However, the specific production rate of the exo-polysaccharide was proportionally increased with the specific growth rate. The proposed model profiles showed good agreement with the experimental results for the mycelial growth and exo-polysaccharide production. The specific production rate using the optimized medium was higher than that of basal medium.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.5
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• pp.179-186
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• 2007

Single crystal $CdGa_2Se_4$ layers were grown on a thoroughly etched semi-insulating GaAs(100) substrate at $420^{\circ}C$ with the hot wall epitaxy(HWE) system by evaporating the polycrystal source of $CdGa_2Se_4$ at $630^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction(DCXD). The carrier density and mobility of single crystal $CdGa_2Se_4$ thin films measured with Hall effect by van der Pauw method are $8.27{\times}10^{17}cm^{-3},\;345cm^2/V{\cdot}s$ at 293 K, respectively. The photocurrent and the absorption spectra of $CdGa_2Se_4/SI$(Semi-Insulated) GaAs(100) are measured ranging from 293 K to 10 K. The temperature dependence of the energy band gap of the $CdGa_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation $E_g(T)=2.6400eV-(7.721{\times}10^{-4}eV/K)T^2/(T+399K)$. Using the photocurrent spectra and the Hopfield quasicubic model, the crystal field energy(${\Delta}cr$) and the spin-orbit splitting energy(${\Delta}so$) far the valence band of the $CdGa_2Se_4$ have been estimated to be 106.5 meV and 418.9 meV at 10 K, respectively. The three photocurrent peaks observed at 10 K are ascribed to the $A_{1^-},\;B_{1^-},\;and\;C_{11}-exciton$ peaks.

• Korean Journal of Food Science and Technology
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• v.34 no.2
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• pp.151-156
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• 2002

Five kinds of red wine from three different grape varieties, Gerbong (G), Campbell (C), Moru (M), Gerbong+Moru (70:30, GM) and Gerbong+Campbell (70:30, GC), were prepared. Their chemical and microbiological changes were monitored during alcohol fermentation and aging. The changes of pH, brix and total acidity were $3.2{\sim}3.6,\;17.9{\sim}6.0$ and $2.4{\sim}4.6\;g/L$, respectively. The viable cell numbers of initial, stationary and death phases were $6.0{\times}10^6,\;1.0{\times}10^8$ and $7.0{\times}10^5\;cfu/mL$ during alcohol fermentation. The sugar fermentability, glucose and fructose contents were greatly decreased less than 0.2 g/L, and the final contents of ethanol and sulfur dioxide were $11.4{\sim}12.3%$ and $40{\sim}62\;mg/L$, respectively. The conversion ratios of malic acid to lactic acid were 23% (G), 67% (M), 28% (C), 33% (GM) and 39% (GC). The chemical characteristics of five red wine were significantly different in pH, total acidity, sulfur dioxide and lactic acid contents (p<0.05).

• Journal of the Korean Electrochemical Society
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• v.23 no.2
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• pp.25-38
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• 2020

Photoelectrochemical water splitting has been considered as the most promising technology for generating hydrogen energy. Transition metal dichalcogenide (TMD) compounds have currently attracted tremendous attention due to their outstanding ability towards the catalytic water-splitting hydrogen evolution reaction (HER). Herein, we report the synthesis method of various transition metal dichalcogenide including MoS₂, MoSe₂, WS₂, and WSe₂ nanosheets as excellent catalysts for solar-driven photoelectrochemical (PEC) hydrogen evolution. Photocathodes were fabricated by growing the nanosheets directly onto Si nanowire (NW) arrays, with a thickness of 20 nm. The metal ion layers were formed by soaking the metal chloride ethanol solution and subsequent sulfurization or selenization produced the transition metal chalcogenide. They all exhibit excellent PEC performance in 0.5 M H₂SO₄; the photocurrent reaches to 20 mA cm^-2 (at 0 V vs. RHE) and the onset potential is 0.2 V under AM1.5 condition. The quantum efficiency of hydrogen generation is avg. 90%. The stability of MoS₂ and MoSe₂ is 90% for 3h, which is higher than that (80%) of WS₂ and WSe₂. Detailed structure analysis using X-ray photoelectron spectroscopy for before/after HER reveals that the Si-WS₂ and Si-WSe₂ experience more oxidation of Si NWs than Si-MoS₂ and Si-MoSe₂. This can be explained by the less protection of Si NW surface by their flake shape morphology. The high catalytic activity of TMDs should be the main cause of this enhanced PEC performance, promising efficient water-splitting Si-based PEC cells.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.237-237
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• 2012

토파즈는 Al2SiO4 ((F,OH)2) 화학성분을 이루고 있는 광물로써 주로 Fe, Cr, V 등과 같은 불순물을 포함하고 있다. 토파즈는 colorless, blue, pink, yellow 등 다양한 컬러로 산출된다. 결정 내 Si4+ 가 있어야 할 자리에 Al3+ 가 치환되면 Al3+ 를 둘러싸고 있는 4개의 산소 중 하나의 최외각 전자가 전자가를 맞추기 위해 주변에 있던 수소와 결합하여 hole center를 형성한다. 이때 토파즈는 옅은 황색의 컬러를 발색하게 된다. 그 외 청색과 핑크색 등의 컬러는 Al3+ 자리에 치환된 Fe, Cr 등과 같은 불순물에 의해 발색을 일으킨다. 또한 토파즈는 인위적으로 감마선, 전자 빔, 양성자 빔, 중성자 빔을 통해서도 hole center를 형성시켜 컬러를 발색시킬 수 있다고 잘 알려져 있다. 본 연구에서는 총 8개의 무색 토파즈를 이용하여 다양한 조건(energy 및 dose)의 전자 빔 조사를 통해 각 조건 별 컬러변화 및 분광학적 특성변화를 관찰하였다. 모든 시료는 WD-XRF를 통해 정성분석을 하였고, 전자스핀공명(ESR)기기를 통해 전자 빔 조사 전과 후 전자의 스핀 특성 변화를 관찰하였다. 자외선-가시광선 분광분석결과 모든 시료는 전자빔 조사 후 황색과 관련이 있는 450 nm 부근의 파장 영역에서 흡수 peak가 증가하는 것을 확인할 수 있었다. 또한 전자 빔 조사 후 전자스핀공명 분석 결과에서도 Fe3+ 와 관련이 있는 g=3.5~4 영역은 감소하는 반면에 hole center와 관련이 있는 g=2.012 영역이 증가하는 향상을 보였다. 본 연구결과를 통해 우리는 전자 빔 조사 조건에 따라 토파즈의 결정 내부에 미치는 영향 및 컬러 변화와의 상관관계에 대해 확인할 수 있었다.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.679-684
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• 1997

The major constituents in spent FCC catalysts are Si, Al, Fe, Ti, alkali metals and some others. The spent catalyst is also composed small amounts of rare metals such as Ce, Nd, Ni and V. The selective adsorption and concentration of Ce and Nd from the leaching solution of spent FCC catalysts with sulfuric acid($0.25mol/dm^3$) were carried out by the column method with a chelate resin having a functional group of aminophosphoric acid type. Ce and Nd were separated from eluate liquor containing Al, Nd and V by the precipitation process with oxalic acid. Vanadium is purified from chloride ion coexistance by solvent extraction, employing tri-n-octyl phosphine oxide as extractant with Al in the raffinate solution. Rare metals with the purity of 99 percent were obtained from the spent FCC catalyst.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.336-336
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• 2017

High mortality and slow growth of seedling generally occurred in tray due to cold, foggy weather and severe seedling blight. Mechanical transplanting is hampered, farmers having economic loss. A sustainable method for raising mat type seedling is necessary. Experiments were conducted on disease control and seedling growth in dry seasons. Fungicides treated/untreated seeds were sown 120-130g in each tray containing pulverized fine grain loam/sandy loam soils. Seed covered with a thin layer of soil and irrigated. It was polythene covered (PC) for 72h and then every night along with 2/3 sprinkler irrigation (SI) per day. Untreated seedlings infected 53-93%. Pyraclostrobin, Azoxystrobin and Azoxystrobin+Difeconazole treated seeds/sprayed (72h) seedlings had no disease. Seedling height was 11.7-13.2 cm with compact and thick root mat at 25 days. Seeds treated at 0.2-0.3% (18-20h) showed no disease but severely in untreated seeds in all locations. Seedling height (13.8 cm), leaf age (3.7) and root number (8.5) were better when NPK were applied at 3-4-3 g/tray. Spraying of urea (1%) in addition with MOP, theovit and $ZnSo_4$ at 0.6-0.6-0.2% on 7 and $15^{th}$ days was also effective. PC showed significant growth (29.1-34.5%). Root mat was not good in flooded irrigation (FI). Disease was higher in SI (66.7-97.3%) than FI (0.7-3.7%) in untreated seeds regardless of polythene use. The protocol would be effective for raising mat type seedling in cold environment.