• Journal of Plant Biology
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• v.36 no.3
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• pp.259-266
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• 1993

In Tris-iso-butanol (TIB; Tris buffer pH 8.8 and 1% iso-butanol)-treated chloroplasts, oxygen evolving activity was more inhibited than Tris-treated chloroplasts, but restored highly by 2,6-dichlorophenol-indophenol (DCPIP) and photoreactivation. To understand the mechanism of this results of TIB in photosynthetic electron transport, system, oxygen consumption and evolution of PS I and PS II were measured and protein of the chloroplasts was analysed. In Tris- and TIB-treated chloroplasts, oxygen evolving activity was increased according to the light intensity. Under 48 W·m-2 light intensity, the oxygen evolving activity in both chloroplasts were similar but as the light intensity was increased, TIB-treated chloroplasts showed higher activity. Under 240 W·m-2 light intensity, TIB-treated chloroplasts showed about 25% higher oxygen evolving activity than Tris-treated chloroplasts. Oxygen evolving activity was increased after photoreactivation in both Tris-treated and TIB-treated chloroplasts. Addition of NH4Cl increased the activity in both chloroplasts but in TIB-treated chloroplasts the increase was 30% higher than that in Tris-treated chloroplasts. In PS I, oxygen evolving activity was not inhibited by both treatments whereas in PS II, significant difference was observed between two treatments. Addition of Mn2+ and Ca2+ enhanced oxygen evolution in both Tris- and TIB-treated chloroplasts. Though enhancement was higher in TIB-treated chloroplasts. No difference was observed n protein analysis of the two thylakoid membrane.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.516-516
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• 2013

Flexible Display를 제작하기 위해서는 유기소자를 보호하는 보호막이 필요하다. 유기소자는 산소 및 수분에 매우 취약하기 때문에 장수명을 확보하기 위해서는 추가적인 보호층이 필요하다. 본 논문에서는 이를 위해 Encapsulation 중 한 방법인 Barrier Film을 제작하고 그에 따른 광학적인 특성 및 수분 투습율을 조사하였다. Barrier film의 광학적 분석 방법으로는 XPS, SEM, AFM, Transmittance를 측정하였으며, XPS는 박막내의 화학적인 결합을 알기 위해서 사용되었고, SEM은 박막의 두께 및 박막내의 결함을 파악하고자 하였다. SEM을 통해 증착속도가 32.6 nm/m이라는 것을 관찰할 수 있었다. AFM을 통해 증착된 박막의 표면 거칠기를 파악하였다. Transmittance는 PET 기판을 사용하여 가시광 영역에서 80%이상의 투과도를 나타내었다. PECVD 장비를 사용하여 SiH4, NH3, N2가스를 사용하여 PET 필름 위에 박막을 증착하였으며, 유량을 10~400 sccm 내에서 변화시키고, RF Power는 각각 30~300 W 15분간 증착하였다. 제작된 보호막의 수분투습율은 $2{\times}10{_2}^{-2}g/m^2/day$ 이하의 값을 나타내었다.

• Environmental Engineering Research
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• v.21 no.1
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• pp.36-44
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• 2016

Constructed wetlands are established efficient technologies and provide sustainable solution for wastewater treatment. Similarly, biochar, which is an organic material, produced by means of pyrolysis, offers simple and low cost techniques to treat water and reduce carbon footprint. Combining both of these technologies can greatly augment the efficiency of the system. The objective of this study was to evaluate the efficiency of constructed wetlands by using biochar as media. Horizontal wetland beds with dimension ($1m{\times}0.33m{\times}0.3m$) were prepared using gravels and biochar, and cultivated with the Canna species. Synthetic wastewater was passed through these beds with average flow rate of $1.2{\times}10^{-7}m^3/sec$ achieving a retention time of three days. Pollutant removal performance was compared between the controlled and experimental wetland beds. This study reveals that the wetland with biochar were more efficient as compared to the wetland with gravels alone with average removal rate of 91.3% COD, 58.3% TN, 58.3% $NH_3$, 92% $NO_3-N$, 79.5% TP, and 67.7% $PO_4$.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1289-1292
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• 2010

용수부족 현상을 극복하기 위하여 댐건설 등의 생태계의 교란을 일으키는 방안을 배제하고 친생태적인 우수이용 등의 대체수자원을 개발하여 수자원 이용효율을 높이는 방안이 중요시 되고 있다. 이에 본 연구에서는 초기우수의 수질특성과 대기의 상태에 크게 영향을 미치는 수문학적 요인인 선행강우에 따른 수질변화에 대하여 분석하였다. 시료채취기간은 2001년 11월 22일에서 2003월 7월 06일까지 발생한 5mm 이상 호우사상을 대상으로 26회 에 걸쳐 초기 우수를 채집하여 분석을 실시하였으며, 이 중 봄 12회, 여름 7회, 가을 2회, 겨울 5회였다. 강우량 규모는 5~10mm인 호우가 5회, 10~20mm인 호우가 9회, 20mm~30mm인 호우가 5회, 30mm~50mm 인 호우가 2회, 50mm~100mm인 호우가 3회, 100mm~200mm인 호우가 2회였으며, 이를 채취하여 탁도, 증발잔유물, BOD, NH3-N, ${SO_4}^{-2}$, 전기 전도도 등의 항목을 측정하였다. 우수수질은 강우가 지속됨에 따라 급격히 개선되었으며, 이에 대한 상관관계도 높게 분석되었다.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1274-1276
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• 1993

The silicon-nitride films formed by laser CVD method are used for passivating GaAs surfaces. The electrical Properties of metal-insulator-GaAs structure are studied to determined the interfacial characteristics by C-V curves and deep level transient spectroscopy(DLTS). The SiN films are photolysisly deposited from $SiH_4\;and\;NH_3$ in the range of $100^{\circ}C-300^{\circ}C$ on P type, (100) GaAs. The hysteresis is reduced and interface trap density is lowered to $10^{12}-10^{13}$ at $100^{\circ}C-200^{\circ}C$. The surface leakage current is studied too. The passivated GaAs have a little leakage current compared to non passivated GaAs.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.200.1-200.1
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• 2013

실리콘 태양전지 표면에는 구조적인 결함에 의해 소수 캐리어의 재결합이 일어난다. 재결합에 의해 캐리어의 반송자 수명은 줄어들게 되고, 태양전지의 효율은 감소하게 된다. 이를 줄이기 위해 태양전지 전 후면에 패시베이션을 하게 되는데, 이번 연구는 단결정 실리콘 태양전지 전면에 SiNx막을 증착함으로 수소 패시베이션이 반송자 수명에 미치는 영향에 대하여 연구하였다. 공정을 위해 $156{\times}156mm^2$, 200 ${\mu}m$, 0.5-3.0 ${\Omega}{\cdot}cm$ and p-type 단결정 실리콘 웨이퍼를 사용하였고, SiNx막을 올리기 전에 KOH 8.5% 용액으로 SDR을 실행하였다. RF-PECVD 장비로 SiNx 막을 증착하였고 증착 온도는 $200{\sim}400^{\circ}C$, 반응기 내부의 압력을 200~1,000 mtorr, SiH4/NH3/N2 각각의 가스 비율 조절, 그리고 플라즈마 RF power 변화시킴에 따라 증착된 SiNx막의 균일도 및 특성을 분석하였다. 반사광 측정 장비인 Reflectometer장비로 막의 두께와 굴절률, 반사율을 측정하였고, 반송자 수명을 측정하여 태양전지의 표면결함을 최대한 패시베이션 시켜주는 조건에 대한 연구를 수행하였다.

• Korean Journal of Metals and Materials
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• v.48 no.10
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• pp.929-935
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• 2010

The solvent extraction behavior of Sn(IV) from hydrochloric acid was investigated using Alamine336 (Tri-n-cotylamine) as an extractant. The experimental parameters of the concentration of the HCl solution, chloride ions, extractant, and Sn(IV) were assessed. The results showed that the extraction percentage of Sn(IV) was more than 95% in our experimental range and was only slightly affected by the HCl concentration. The extraction reaction of Sn(IV) by Alamine 336 from the chloride solution was identified as follows: $SnCl_6{^{2-}}+2R_3NHCl_{(org)}=(R_3NH)_2SnCl_{6(org)}+2Cl^-$ and $K=6.3{\times}10^4$. Stripping experiments of Sn(IV) from the loaded organic phase were done by using several stripping agents. A stripping percentage of 90% was obtained with a 2.0 M NaOH solution.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.745-751
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• 2011

In most agricultural soils, ammonium ($NH_4^+$) from fertilizer is quickly converted to nitrate ($NO_3^-$) by the process of nitrification which is crucial to the efficiency of N fertilizers and their impact on the environment. However, nitrification studies have been studied extensively in agricultural soils, not in a newly reclaimed tidal soil which show saline-sodic and high pH. Therefore, understanding the fate of nitrogen species transformed from urea introduced into reclaimed tidal soil is important for nutrient management and environmental quality. This paper reviewed studies regarding to transformation and fate of nitrogen sources such as urea under the circumstances of a reclaimed tidal soils located in a western coastal area.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.283-293
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• 2008

The objectives of the study were firstly to provide fundamental data for establishment of total maximum daily load (TMDL) management in Ulsan City, and secondly to make practical application of stream health assessment with tolerance range by each species when physiochemical and fish investigations were carried out together. A total of 44 sites in Taehwa River, Hoiya River, Dong Stream, and Cheongryang Stream were selected to monitor water qualities seasonally and fish investigation was performed in August 2006. Among the parameters of water quality, biological oxygen demand (BOD) and dissolved oxygen (DO) related to respiration, total nitrogen (T-N) and total phosphorus (T-P) related to nutrient and eutrophication, and total suspended solids (TSS) and $NH_4$-N were compared with vertical box plot by 8 dominant species. According to the fish investigation, 12 families 33 species were found including endangered species (Pungitius kaibarae) and introduced species (Lepomis macrochirus, Micropterus salmoides), and appearance rate of Korean endemic species was greater in Taehwa River (29.2%) than others. As the results of tolerance range by species, Zacco koreanus, Rhynchocypris oxycephalus, Iksookimia longicorpa, and Squalidus gracilis majimae had limited low range by water quality parameters indicating preference of good water quality. Whereas, Carassius auratus and Pseudorasbora parva were found downstream and urban-streams which were exposed from frequent inflow of pollutants. It concludes that the results help distinguishing sensitive, intermediate, and tolerant species when we evaluate stream health assessment with fish, and further making practical application for conservation and restoration of aquatic ecosystem.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.10
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• pp.1400-1410
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• 2004

Eight crossbred (75% Holstein Friesian) cows in mid-lactation were randomly assigned to a switchback design with a 2x2 factorial arrangement to evaluate two nonstructural carbohydrate (NSC) sources (corn meal and cassava chips) with different rumen degradability and used at two levels of NSC (55 vs. 75%) with protein source (supplied by urea in the concentrate mix). The treatments were 1) Low degradable low level of corn (55%) 2) Low degradable high level of corn (75%) 3) High degradable low level of cassava (55%) and 4) High degradable high level of cassava (75%). The cows were offered the treatment concentrate at a ratio to milk yield at 1:2. Urea-treated rice straw was offered ad libitum as the roughage and supplement with 1 kg/hd/d cassava hay. The results revealed that total DM intake, BW and digestion coefficients of DM were not affected by either level or source of energy. Rumen fermentation parameters; NH3-N, blood urea nitrogen and milk urea nitrogen were unaffected by source of energy, but were dramatically increased by level of NSC. Rumen microorganism populations were not affected (p>0.05) by source of energy, but fungal zoospores were greater for cassava-based concentrate than corn-based concentrate. Milk production and milk composition were not affected significantly by diets containing either source or level of NSC, however concentrate than corn-based concentrate averaging (4.4 and 4.2, respectively). Likewise, income over feed, as estimated from 3.5% FCM, was higher on cassava-based concentrate than corn-based concentrate averaging (54.0 and 51.4 US$/mo, respectively). These results indicate that feeding diets containing either cassava-based diets and/or a higher of oncentrates up to 75% of DM with NPN (supplied by urea up to 4.5% of DM) can be used in dairy rations without altering rumen ecology or animal performance compared with corn-based concentrate.