• Applied Science and Convergence Technology
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• 제25권4호
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• pp.73-76
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• 2016

Multi-layer films of $SiN_x/SiO_x$/InSnO with anti-reflective effect were grown by new-concept plasma enhanced chemical vapor deposition system (PECVD) with hybrid plasma source (HPS). Anti-reflective effect of $SiN_x/SiO_x$/InSnO was investigated as a function of ratio of $SiN_x$ and $SiO_x$ thickness. Multi-layers deposited by PECVD with HPS represents the enhancement of anti-reflective effect with high transmittance, comparing to the layers by conventional radio frequency (RF) sputtering system. This change is strongly related to the optical and physical properties of each layer, such as refractive index, composition, film density, and surface roughness depending on the deposition system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.259-259
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• 2010

교류 전기장에 의해 배열된 ZnO 나노선 기반의 광다이오드를 제작하고 자외선 광특성을 조사하였다. ZnO 나노선은 dielectrophoresis (DEP) force와 토크 (T)에 의하여 두 전극사이에 배열되며, silicon (Si)나노선과 접합을 하여 p-n 접합을 형성한다. 형성된 p-n 접합은 정류작용을 하는 다이오드 특성을 보이며, 자외선 입사시 전류 점멸비 (on/off ratio) $10^1{\sim}10^2$을 보이는 광다이오드(photodiode)로서 동작한다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.207-207
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• 2010

Both ZnO and GaN have excellent physical properties in optoelectronic devices such as blue light emitting diode (LED), blue laser diode (LD), and ultra-violet (UV) detector. The ZnO/GaN heterostructure, which has a potential to achieve the cost efficient LED technology, has been fabricated by using radio frequency (RF) sputtering, pyrolysis, metal organic chemical vapor deposition (MOCVD), direct current (DC) arc plasmatron, and pulsed laser deposition (PLD) methods. Among them, the PLD system has a benefit to control the composition ratio of the grown film from the mixture target. A 500-nm-thick ZnO film was grown by PLD technique on c-plane GaN/sapphire substrates. The post annealing process was executed at some varied temperature between from $300^{\circ}C$ to $900^{\circ}C$. The morphology and crystal structural properties obtained by using atomic force microscope (AFM) and x-ray diffraction (XRD) showed that the crystal quality of ZnO thin films can be improved as increasing the annealing temperature. We will discuss the post-treatment effect on film quality (uniformity and reliability) of ZnO/GaN heterostructures.

• 조명전기설비학회논문지
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• 제26권3호
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• pp.9-15
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• 2012

In this paper, we deal with a surface discharge that caused an aggravation of the dielectric strength in the $N_2/O_2$ mixture gas, When composit dielectrics were formed from the use of a solid dielectric. It was found from this study that the surface discharge voltage was deeply involved in the mixture ratio of $O_2$, the electrical property of the solid dielectric, kind of the solid dielectric, an electric field at the triple junction and a medium effect. These results expect basic data that will be used to transmission and distribution power system equipment using the $N_2/O_2$ mixture gas.

• Journal of Plant Biology
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• 제13권2호
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• pp.21-31
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• 1970

The rice variety, Nongkwang was used in two factorial experiments with the combination of 15 kg and 20 kg of N per 10 a, 3 levels of P2O5 (0, 4 and 8 kg per 10 a) and 4 levels of potash(0, 2, 4 and 8 kg per 10 a) in the reclaimed soil areas containing 0.48% on the average salt content throughout the year(0.67% at the end of April). The absorption of N, K and Ca was accelerated by increased N applications. The absorption of P itself was not enhanced by the increased application of P2O5 but the absorption of K2O reduced the absorption of Mg was affected. The increased application of K2O reduced the absorption of Si and seemed to increase the content of carbohydrate in the rice plants. Twenty kg of N and 4kg of P2O5 per 10 a produced satisfactory yields of rough rice, potash applications are ineffective in this experiment on rice grain production.

• 한국결정성장학회지
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• 제14권3호
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• pp.101-104
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• 2004

결정내부에 존재하는 인클루전의 구성성분 및 결정학적인 구조를 분석하기 위해서는 기존의 normal XRD 분석 장비에 비해, 수십 $\mu\textrm{m}$ 크기의 결정입자에 대해 X-선 빔을 포커싱(focusing)하여 높은 S/N비로 분석할 수 있는 MC-XRD(Multi-Channel Ray Diffractome)가 매우 유용하였다. 이러한 MC-XRD로 분석한 결과, 루틸로 알려져 있는 커런덤내에 함유된 침상내포물은 iron titanium oxide, iron oxide들로 이루어져 있었고, 각각은 $Fe_2TiO_4,\; Fe_2TiO_5,\; Fe_2O_3$와 같은 화학조성을 가짐을 알았다.

• 한국표면공학회지
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• 제38권5호
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• pp.193-197
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• 2005

Highly c-axis oriented Zinc oxide (ZnO) films were successfully deposited at room temperature by oxygen ion-assisted pulsed filtered vacuum arc. The effect of oxygen gas ratio ($O_{2}/O_{2}+Ar$ on the preferred orientation, surface morphology and resistivity of the ZnO films were investigated. Highly crystalline ZnO films with (002) orientation were obtained at over $13\%$ of oxygen gas ratio. Increasing oxygen gas ratio up to $80\%$ was found to improve crystallinity of the films. From hall measurements, it was found that the film has n-type characteristic and carrier concentration and its mobility were closely related with oxygen gas ratio. Minimal resistivity of $3.6{\times}10^{-3}{\Omega}{\cdot}cm$ was obtained in the range of $20\%$ to $40\%$ of oxygen gas ratio.

• 한국물환경학회지
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• 제21권6호
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• pp.643-650
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• 2005

In order to treat leachate from aged landfill site effectively, removal of biologically recalcitrant organic matter and denitrification efficiency were evaluated through the combination of $H_2O_2/O_3$ AOP pretreatment process and UASB process. The results can be summarized as follows. In case of leachate having low COD/N ratio from aged landfill site, it is possible to increase available COD for denitrification in nitrate utilizing denitrification and nitrite utilizing denitrification both by enhancing biodegradability of recalcitrant organic matter as applying $H_2O_2/O_3$ AOP to pretreatment process. In this experiment, it is found that available COD for denitrification can be increased to 1.0 and 0.4 g/day, respectively. Comparison has been made between requiring COD and available COD for denitrification in each experimental stages. It is expected that high rate of denitrification can be achieved with leachate from young landfill site because higher amount of available COD for denotrification is present in the leachate than the amount of requiring COD for denitrification. Especially, In leachate from aged landfill site with low COD/N ratio, it can be concluded that denitrification using nitrite nitrogen can enhance overall denitrification performance efficiently because denitrification using nitrite nitrogen requires less amount of carbon source than denitrification using nitrate nitrogen. Comparing the biogas production rate and nitrogen content of biogas under the condition of same amount of nitrate and nitrite addition, biogas production and nitrogen content of biogas are increased during denitrification after $H_2O_2/O_3$ AOP pretreatment process. Therefore, it can be confirmed that COD/N ratio in the leachate is increased. Applying $H_2O_2/O_3$ AOP as pretreatment system of landfill leachate seems to have little economic benefit because it requires additional carbon source to denitrify ammonia nitrogen in leachate coming from aged landfill site. However, it is possible to apply this pretreatment process to leachate from old landfill site in view of AOP process can achieve removal of biologically recalcitrant organic matter and increase of available COD for denitrification simultaneously.

• 한국농림기상학회지
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• 제5권1호
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• pp.1-5
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• 2003

수원 지역의 영농기간중 강우의 화학적 특성을 알아보기 위하여 1999년 및 2000년 2년 간 4월부터 10월까지 각각 1개월 동안 수원지역에 내린 빗물의 화학적 성분조성과 강우량을 고려한 가중평균(volume-weighted mean) 이온농도 변화를 조사한 결과는 다음과 같다. 조사 기간 중 강우 pH는 편서풍의 영향을 받는 기간인 4월이 6월 이후의 강우에 비해 높게 나타나 계절적 특성을 보였다. 강우시료에 대한 pH별 강우 분포는 pH 5.6 이상이 45.1%로 가장 많았으며, pH 5.6∼5.0 및 4.5∼4.9 범위의 강우가 각각 31.4%와 19.6%를 차지하였다. 빗물의 조성은 S $O_4$가 음이온의 50%이상을 차지하였고 전체 양이온 함량의 약 65% 가 N $H_{4}$$^{+}$와 $Ca^{2+}$로 구성되어 있다. 월별 빗물 pH는 측정치(p $H_{/obs}$)는 6월에서 9월 사이에 낮은 반면, 이론치(p $H_{\the}$)는 같은 기간에 증가하여 대기중의 알카리성 물질들에 의한 중화력이 다른 기간에 비해 낮았다. 또한, 강우중 비해염 sulfate는 총 sulfate 함량의 약 93.6%이었다. 강우의 산성도 기여율(nss-S $O_{4}$$^{2-}$ /N $O_{3}$$^{-}$)은 평균 2.1로 비해염 S $O_{4}$$^{2-}$ 에 의한 기여율이 N $O_{3}$$^{-}$ 보다 약 2배 가량 높았다.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1915-1919
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• 2010

Second-order rate constants $(k_N)$ have been measured for reactions of 2,4-dinitrophenyl phenyl carbonate (2) with a series of pyridines in 80 mol % $H_2O$/20 mol % DMSO at $25.0{\pm}0.1^{\circ}C$ and compared with the $k_N$ values reported for the corresponding reactions of 2,4-dinitrophenyl benzoate (1) to investigate the effect of nonleaving group on reactivity and mechanism. The reactions of 2 result in larger $k_N$ values than those of 1. The Br${\o}$nsted-type plot for the reactions of 2 exhibits a downward curvature (i.e., ${\beta}2$ = 0.84 and ${\beta}1$ = 0.16), which is typical for reactions reported to proceed through a stepwise mechanism with a change in rate-determining step. The $pK_a$ at the center of the Br${\o}$nsted curvature, defined as $pK_a{^{\circ}}$, has been found to be 8.5 and 9.5 for the reactions of 2 and 1, respectively. Dissection of $k_N$ into the microscopic rate constants (e.g., $k_1$ and $k_2/k_{-1}$ ratio) has revealed that the reactions of 2 result in larger k1 values than those of 1, indicating that PhO behaves as a stronger electron-withdrawing group than Ph. However, the $k_2/k_{-1}$ ratio has been found to be independent of the electronic nature of Ph and PhO.