• 태양에너지
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• 제6권1호
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• pp.12-23
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• 1986

The PECVD $SiN_x:H$ films were made from the $SiH_4-N_2$ gas mixtures under such deposition conditions as 0.01 to 1.0 of $SiH_4/N_2$ volume ratio, 0.1 to $0.8W/cm^2$ of RF power, and 100 to $400^{\circ}C$ of substrate temperature. The deposition rate, refractive index, hydrogen concentration, N/Si composition, optical gap and electric conductivity were measured, and the thermal stability and the optimum deposition conditions were investigated for the application of these films to the solar cell materials.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.582-588
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• 2014

We study polarization-dependent spontaneous emission (SE) rate and light extraction efficiency (LEE) in localized-surface-plasmon (LSP)-coupled light emitting diodes (LEDs). The closely packed seven $Ag/SiO_2$ core-shell (CS) nanoparticles (NPs) lie on top of the GaN surface for LSP coupling with a radiated dipole. According to the dipole direction, both the SE rate and the LEE are significantly modified by the LSP effect at the $Ag/SiO_2$ CS NPs when the size of Ag, the thickness of $SiO_2$, and the position of the dipole source are varied. The enhancement of the SE rate is related to an induced dipole effect at the Ag, and the high LEE is caused by light scattering with an LSP mode at $Ag/SiO_2$ CS NPs. We suggest the optimum position of the quantum well (QW) in blue InGaN/GaN LEDs with $Ag/SiO_2$ CS NPs for practical application.

• 대한통합의학회지
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• 제4권4호
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• pp.77-82
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• 2016

Purpose: The purpose of this study was to investigate the therapeutic effect of non-invasive vagus nerve stimulation by transcutaneous electrical nerve stimulation application on the autonomic nervous system of human body. Methods: Participants were seventeen healthy adults. Standard deviation of all normal N-N intervals(SDNN), root mean square of successive differences(RMSSD), low frequency(LF), high frequency(HF) were compared in pre and post Mean values after intervention. Data were analyzed in Wilcoxon's signed-ranks test. Results: The results of this study is that sistolic blood pressure and pulse rate decreased mean value after non-invasive vagus nerve stimulation by transcutaneous electrical nerve stimulation. High frequency, low frequency, SDNN, RMSSD increased mean value in heart rate variability after intervention. But that is not significant except for SDNN. Conclusion: Non-invasive vagus stimulation by transcutaneous electrical nerve stimulation effect on parasympathetic nerve stimulation, and then it might be effective method for autonomic nerve balance control.

• 상하수도학회지
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• 제21권6호
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• pp.679-687
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• 2007

Nanoscale zero valent ion (nZVI) technology is emerging as an innovative method to treat contaminated groundwater. The activity of nZVI is very high due to their high specific surface area, and supporting this material can help to preserve its chemical nature by inhibiting oxidation. In this study, nZVI particles were attached to granular ion-exchange resin through borohydride reduction of ferrous ions, and chemical reduction of nitrate by this material was investigated as a potential technology to remove nitrate from groundwater. The pore structure and physical characteristics were measured and the change by the adsorption of nZVI was discussed. Batch tests were conducted to characterize the activity of the supported nZVI and the results indicated that the degradation of nitrate appeared to be a pseudo first-order reaction with the observed reaction rate constant of $0.425h^{-1}$ without pH control. The reduction process continued but at a much lower rate with a rate constant of $0.044h^{-1}$, which is likely limited by mass transfer. To assess the effects of other ions commonly found in groundwater, the same experiments were conducted in simulated groundwater with the same level of nitrate. In simulated groundwater, the rate constant was $0.078h^{-1}$ and it also reduced to $0.0021h^{-1}$ in later phase. The major limitation in application of ZVI for nitrate reduction is ammonium production. By using a support material with ion exchange capacity, the problem of ammonium release can be solved. The ammonium was not detected in the batch test, even when other competitive ions such as calcium and potassium existed.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2007년도 춘계학술발표회 초록집
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• pp.71-72
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• 2007

In this study, we investigated the fabrication of MLR (multi-layer resist) with a very thin diamond-like carbon (DLC) layer. ArF PR/$SiO_2$/DLC MLR structure was investigated and etching characteristics of the DLC layer was patterned using $SiO_2$ hard-mask by varying the process parameters such as different high-frequency/low-frequency combination ($f_{LF}/f_{HF}$), HF/LF power ratio ($P_{HF}/P_{LF}$), $O_2$ flow and $N_2$ flow rate in $O_2/N_2$/Ar plasmas. The results indicated an increased etch rate of DLC for the higher $f_{LF}/f_{HF}$ combination and for the increased low-frequency power ($P_{LF}$). And the etch rate of DLC was decreased with increasing the $N_2$ flow rate in $O_2/N_2$/Ar plasmas. In order to confirm the application of DLC MLR for the etching process of silicon oxide, the stack of ArF PR/BARC/$SiO_2$/DLC/TEOS/Si was investigated.

• 한국작물학회지
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• 제26권3호
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• pp.257-262
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• 1981

Orchardgrass 초지에 있어서 조성 초기의 질소시비에 대한 생장 및 수량반응과 질소이용성에 관한 기초자료를 얻기 위하여 1979년 4월에 서울대 농대 실험 농장에서 품종 Potomac을 파종하여 연간 100, 200, 400, 800 kg/ha 수준의 질소비료 시용실험을 난괴법 3반복으로 수행하였다. 그 결과는 다음과 같았다. 1. 파종 첫해의 최대 건물수량 및 최대 질소회수율을 보인 수준은 200kg.N/ha.year였으나 다음 해에는 400kg.N/ha.year였다. 2. 재생기간중의 엽면적지수(LAI)와 순동화율(NAR) 및 체내 전질소함량은 질소증시와 함께 증가했으며 최대 작물생장속도(CGR)는 LAI 5 정도에서 얻어졌다. 3. 채내 ${NO_3}^-$-N 농도는 연간 200kg.N/ha 수준 이상에서 급격히 증가하여 800kg.N/ha 수준에서 중독위험치(1,500ppm ${NO_3}^-$-N)를 초과하였다.

• 한국토양비료학회지
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• 제28권2호
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• pp.160-164
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• 1995

농경지에 시용되는 질소질 비료의 대부분을 차지하는 요소를 대상으로 수도재배포장에서 요소태(Urea-N)와 암모늄태($NH_4-N$) 및 질산태($NO_3-N$) 질소의 농토를 조사함으로써 논토양에 시용되는 요소비료의 효율 증대 및 환경오염 방지에 기초가 되는 정량적인 자료를 얻고자 요소를 12kg N/10a(관행구)와 24kg N/10a(배비구) 수준으로 시용한 수도재배포장에서 수도재배기간 동안 침투수의 Urec-N, $NH_4-N$ 및 $NO_3-N$의 농도를 porous ceramic cup을 이용하여 토양깊이별로 조사한 결과는 다음과 같다. 관행구와 배비구 모두 전체 시비량의 50%를 기비로 사용한 후 12일이 지난 후에 채취한 침투수에서는 75cm 깊이에서도 Urea-N이 검출되었으며, 그 농도는 관행구 0.06 및 배비구 $0.12{\mu}g/m{\ell}$로서 배비구에서 높았다. 침투수의 $NH_4-N$ 농도는 수도의 영양생장기간 동안에는 변화가 컸지만 출수가 시작된 8월 중순 이후에는 $0.1{\mu}g/m{\ell}$로서 일정하였다. 침투수의 $NO_3-N$ 농도는 관행구 0.1~0.5 및 배비구 $0.2{\sim}0.5{\mu}g/m{\ell}$ 범위로서 요소 시용량간의 차이는 거의 없었다.

• 센서학회지
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• 제28권6호
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• pp.402-406
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• 2019

Recently, semiconducting organic materials have been spotlighted as next-generation electronic materials based on their tunable electrical and optical properties, low-cost process, and flexibility. However, typical organic semiconductor materials are vulnerable to moisture and oxygen. Therefore, an encapsulation layer is essential for application of electronic devices. In this study, SiN_x thin films deposited at process temperatures below 150 ℃ by plasma-enhanced chemical vapor deposition (PECVD) were characterized for application as an encapsulation layer on organic devices. A single structured SiN_x thin film was optimized as an organic light-emitting diode (OLED) encapsulation layer at process temperature of 80 ℃. The optimized SiN_x film exhibited excellent water vapor transmission rate (WVTR) of less than 5 × 10^-5 g/㎡·day and transmittance of over 87.3% on the visible region with thickness of 1 ㎛. Application of the SiN_x thin film on the top-emitting OLED showed that the PECVD process did not degrade the electrical properties of the device, and the OLED with SiN_x exhibited improved operating lifetime

• Environmental Engineering Research
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• 제21권3호
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• pp.311-317
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• 2016

A new type of biofilter packed with composite carriers was designed for tertiary denitrification of the secondary effluent with removal of both oxidized nitrogen and suspended solids (SS). At the empty bed residence time of 15 min and organic carbon to nitrate nitrogen ($C/NO_3-N$) ratios of 2, 1.5 and 1 g/g, the removal percentage of $NO_3-N$ was 67%, 58% and 36% in the ethanol biofilter, and was 61%, 43% and 26% in the acetate biofilter, respectively. The biofilters packed with composite carriers removed SS effectively, with the effluent turbidity in both biofilters of less than 3 NTU. During the operating cycle between the biofilter backwashings, the $NO_3-N$ removal percentage decreased initially after backwashing, and then gradually increased. Under $C/NO_3-N$ ratios of 2, 1.5 and 1 g/g, the $NO_3-N$ reduction rate was 1.75, 1.04 and $0.68g/m^2/d$ in the ethanol biofilter, and was 1.56, 1.07 and $0.76g/m^2/d$ in the acetate biofilter, respectively. In addition, during denitrification, the ratio of the consumed chemical oxygen demand to the removed $NO_3-N$ was 5.06-8.23 g/g in the ethanol biofilter, and was 4.26-8.6 g/g in the acetate biofilter.

• 한국토양비료학회지
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• 제49권4호
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• pp.388-392
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• 2016

The objectives of fertilizer recommendation are to prevent the application of excessive fertilization and to produce target yields. Also, optimal fertilization is important because crop quality can be influenced by fertilization. In this study, yields and fertilizer use efficiency of Taro (Colocasia esculenta Schott) were evaluated in different level of NPK fertilization. N, P and K fertilizer application rates were 5 levels (0, 50, 100, 150, 200%) by practical fertilization ($N-P_2O_5-K_2O=180-100-150kg\;ha^{-1}$), respectively. In the N treatment, the yields of Taro tuber were about $33Mg\;ha^{-1}$ from 90 to $360kg\;ha^{-1}$ N fertilization. However, the ratio of tuber to total biomass decreased with increasing N fertilization rate. In the P and K treatments, yields of Taro tuber were the highest at $150kg\;ha^{-1}$ fertilization. Fertilizer use efficiency was decreased by increase of N and K fertilization. Crude protein of Taro tuber was the highest at practical fertilization. Sucrose content of tuber was influenced by phosphate application.