• 반도체디스플레이기술학회지
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• 제13권4호
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• pp.21-25
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• 2014

The silicon nitride ($SiN_x$) film for surface passivation and anti-reflection coating of crystalline silicon solar cell is very important and it is generally deposited by plasma enhanced chemical vapor deposition (PECVD). PECVD can be divided into low and high frequency method. In this paper, the $SiN_x$ film deposited by low and high frequency PECVD method was studied. First, to optimize the $SiN_x$ film deposited by low frequency PECVD method, the refractive index was measured by varying the process conditions like $SiH_4$, $NH_3$, $N_2$ gas rate, and RF power. When $SiH_4$ gas rate was increased and $NH_3$ gas rate was decreased, the refractive index was increased. The refractive index was also increased with RF power decline. Second, to compare the characteristics of the low and high frequency PECVD $SiN_x$ film, the refractive index was measured by varying $NH_3/SiH_4$ gas ratio and RF power and the minority carrier lifetime of before and after high temperature treatment process was also measured. The refractive index of both low and high frequency PECVD $SiN_x$ film was decreased with increase in $NH_3/SiH_4$ gas ratio and RF power. After high temperature treatment process, the minority carrier lifetime of both low and high frequency PECVD $SiN_x$ film was increased and increased degree was similar. The minority carrier lifetime of low frequency PECVD $SiN_x$ was increased from $11.03{\mu}m$ to $28.24{\mu}m$ and that of high frequency PECVD $SiN_x$ was increased from $11.60{\mu}m$ to $27.10{\mu}m$.

• 상하수도학회지
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• 제10권3호
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• pp.73-82
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• 1996

The removal efficiencies of organic substrates, nitrogen and phosphorus in the anaerobic-aerobic biological phosphorus removal process were investigated by addition of acetic acid, propionic acid and butyric acid which are normal volatile fatty acids contained in anaerobic digester supernatants. Substrate utilization coefficients for the phosphorus release and uptake were also estimated. The effect of a VFA, which showed higher phosphorus removal efficiency than the other VFAs did, was also studied in an anaerobic-aerobic-anoxic biological nutrient removal process. For the anaerobic-aerobic process added by VFA, the phosphorus removal efficiencies were up to about 68%, 55% and 61% for the reactors of acetic acid, propionic acid and butyric acid added, respectively, which indicates the efficiencies were increased by about 8-21%, comparing to that of 47% for the reactor with no VFA added. There were no significant difference in removal efficiencies for organic substrate and $NH_3-N$ without regard to addition of VFA. However, the removal efficiency of total nitrogen was increased in the case of VFA added, since $NO_3-N$ was less produced. For the anaerobic-aerobic-anoxic process added VFA, the removal efficiencies for $NH_3-N$ and $PO{_4}^{3-}-P$ were increased by 5% and 13%, respectively, comparing with them in the reactors not added VFA.

• 한국결정학회지
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• 제9권1호
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• pp.1-5
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• 1998

[Cu(L)]I2, 2H2o(1) (L:3,14-Dimethyl-2,6,13,17-tetrazatricyclo[14,4,01.18, 07.12] docosane) 착물을 합성하고 구조를 규명하였다. 이 착물은 삼사정계, 공간군 P1, a=8.400(1)Å, b=8.986(3) Å, c=9.156(1) Å, α=82.42(1)˚, β=73.61(1)˚ λ=81.04(2)˚, Z=1로 결정화되었으며, 최종 신뢰도 R값은 288K에서 1926개 회석반점에 대하여 0.042이었다. 이 착물의 결정구조는 평면 사각구조를 갖고 Cu-N의 평균 거리는 2.029(11)Å이었다. 이 착물의 육면 고리가 오면 고리는 RRSS 배역을 갖는 이차 NH와 함께 각각 의자 형태와 고우시 형태를 갖는다.

• 한국식품과학회지
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• 제4권2호
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• pp.72-76
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• 1972

2,2'-methylene bis(3,4,6-trichloroacetoxy benzene)을 모체로 한 7가지 hydroxyamine 유도체의 13가지 균주에 대한 항균성을 paper disk method와 tube dilution method에 의하여 얻은 결과는 다음과 같다. 1) hydroxyamine유도체 중에서 -OH기가 meta위치에 있는 유도체가 다른 유도체보다 항균력이 강하고, para위치에 -OH기가 있는 화합물은 전연 어느 균에도 항균력이 없으며, para위치에 있는 -OH기의 H대신에 $CH_{3-}$기가 치환된 유도체도 항균력이 별로 강하지가 않았다. 2) $-NH\;OH,\;-NH\;CH_2\;CH_2OH$ 및 $-N\;(CH_2\;CH_2\;OH)_2$화합물 중에서 -NH OH화합물이 가장 강하고 나머지 두 화합물은 몇 가지 균주에 대하여 약간의 항균력을 나타내었다. 3) 모든 합성화합물 중에서 -NH OH화합물의 항균력이 제일 강했으며 Brevibacterium ammoniagenes에 대한 M.I.C.는 $1.6{\mu}g/ml$이며, S. aureus와 Bacillus subtilis에 대한 M.I.C.는 $5{\mu}g/ml$이었다.

• 환경위생공학
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• 제19권3호
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• pp.13-21
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• 2004

This study was focused on the evaluation of Nanjido landfill site by leachate analysis. Several parameters, for example pH, BOD, $COD_{Mn},\;COD_{Cr}$, SS, TP, $NH_3-N$, Color, were selected as major leachate quality parameters. $BOD/COD_{Cr}$. was used to estimate the biodegradable portion in organic matter. Samples were collected at the leachate storage wells and leachate treatment facility inflow in each quarter of 2003. The results were as follows : 1. Inflow quality of treatment plant in 2003 was analysed as $pH\;7.3\~8.0,\;BOD\;12.4\~30.0mg/L,\;COD_{Mn}\;101.2\~130.3mg/L,\;COD_{Cr}\;122.5\~238.0mg/L,\;SS\;16.1\~115.3mg/L$, $T-P\;0.27\~0.80mg/L,\;NH_3-N\;208.0\~~354.0mg/L$, Color $110.3\~129.0$ unit. 2. $BOD/COD_{Cr}$ of inflow ranged between $0.07\~0.16$ indicating that the landfill had the properties of old-fill and organic portion in leachate was mostly persistent organic matter. 3. Though concentrations of BOD, COD, $NH_3-N$, Color in leachate storage wells were mostly higher in first landfill than in second landfill, $BOD/COD_{Cr}$ ranging from 0.03 to 0.20, showed reversely. 4. Correlation coefficient$(R^2)$ between color and other parameters related to organic matter showed mostly above 0.7 and especially highest value with $COD_{Mn}$ of 0.7985.

• Journal of Ecology and Environment
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• 제31권3호
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• pp.213-223
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• 2008

The increasing area of abandoned rice fields could provide new opportunities for wetland restoration in Asia. However, it is unknown how quickly or completely abandoned rice fields will recover from agricultural disturbances. We assessed water quality and plant community succession in abandoned rice fields with different hydrology in a mountain valley to understand the effects of hydrological regime on recovery. Water level, soil redox potential, water quality, plant composition, and primary production were measured. The sites, coded as D6, N13, and N16, had been recovering for 6, 13, and 16 years by 2006. N13 and N16 have been recovering naturally whereas D6 has been drained with a nearby dike and was tilled in 2001. The typical hydroperiods of D6, N13, and N16 were no surface water, permanently flooded, and seasonally flooded, respectively. The major change in vegetation structure of both D6 and N13 was the replacement of herbaceous species by woody species. Drawdown accelerated this change because Salix koreensis grew better in damp conditions than in flooded conditions. Phragmites japonica reduced plot-level plant species richness. The removal efficiency of $NH_4-N$, $NO_3-N$, and $PO_4-P$ from water varied seasonally, ranging between -78.8 to 44.3%, 0 to 97.5%, and -26.0 to 44.4%, respectively. In summary, abandoned rice fields quickly became suitable habitat for native wetland plant species and improved regional water quality. Variation among our sites indicates that it is likely possible to manage abandoned rice fields, mostly through controlling hydrology, to achieve site-specific restoration goals.

• 한국환경농학회지
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• 제18권1호
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• pp.6-7
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• 1999

The water quality at Mankyeong River was surveyed 13 sites of main stream for 6 months from April to September in 1995 and 1997. The monthly average value of $NH_4-N$, $SO_4^{2-}$ and $Cl^-$ showed the highest peak in April while that of $NO_3-N$ showed the highest peak in August. The monthly average value of COD showed the highest peak in September at high temperature season. Concentrations of $NH_4-N$ and $SO_4^{2-}$ in Mankyeong River stream exceeded the standard water quality criteria in many sites. The water quality of Mankyeong River stream was not suitable for the irrigation source excepted the sites such as Hari, Gosan stream and Soyang stream. The floodgate of Mokcheon, Yocheon, Jeonju and Samcheon stream were rapidly polluted by the sewage of city, otherwise the Iksan stream was rapidly polluted by the sewage of swine. The sum of ionic concentrations in Mankyeong River stream was the highest at floodgate of Yocheon by influence of the sewage from city and industry. The order of the major anions and cations concentration in Mankyeong River stream were $SO_4^{2-}$ > $Cl^-$ > $NO_3-N$ > $SO_4^{3-}$ and $Na^+$ > $Ca^{2+}$ > $NH_4^+$ > $Mg^{2+}$ > $K^+$, respectively.

• Applied Biological Chemistry
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• 제43권2호
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• pp.124-129
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• 2000

농업유역에서 영양원소들은 시비 후 강우에 의해 지표 유출이 생기면 용해되거나 토사에 흡착된 상태로 하천에 유입되어 부영양화의 주요한 요인이 되고 있다. 농경지로부터의 영양염류 유실 정도를 평가하기 위해 경북 영천군 임고천 유역의 대표적 영농형태인 과수원 토양에 $14.3{\times}24.8\;m$면적의 유출 시험포를 설치하고 1999년 3월부터 11월 사이에 발생한 26개의 강우 사상에 대하여 지표 유출수량과 토양 유실량을 측정하였으며 이들과 함께 발생하는 질소와 인의 유실량을 조사하였다. 시험 포장에는 화학비료와 혼합유박비료로 질소와 인이 각각 112, 46kg/ha씩 처리되었다 조사 기간 동안 발생한 총 표면 유출수량은 $421.5\;m^3/ha$이었고 토양 유실량은 1,989kg/ha이었다. 유출수중의 T-N, $NO_3-N$, $NH_4-N$, T-P 및 $PO_4-P$의 농도는 각각 $4.7{\sim}171.0,\;0.1{\sim}188.0,\;0.13{\sim}3.36,\;0.58{\sim}4.99$ 및 $0.05{\sim}3.71\;mg/l$ 범위였다 강우에 의해 지표면으로 유실된 총 질소량은 16.39 kg/ha였으며 이중 질산태 질소와 암모늄태 질소가 각각 75%와 3%를 차지하였다. 인의 유실량은 총 16.39 kg/ha였으며 이 중에서 이온형태의 인이 47%였으며 토사와 함께 유실되는 인은 27% 정도였다. 질소와 인의 총 유실량은 각각 총 시비량의 9.5% 및 2.3%였다.

• 센서학회지
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• 제13권3호
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• pp.195-198
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• 2004

For a diffusion barrier against copper, tantalum nitride films have been deposited on $SiO_{2}$ by atomic layer deposition (ALD), using PEMAT(Pentakis(ethylmethylamino)tantalum) and $NH_{3}$ as precursors, Ar as purging gas. The deposition rate of TaN at substrate temperature $250^{\circ}C$ was about $0.67{\AA}$ per one cycle. The stability of TaN films as a Cu diffsion barrier was tested by thermal annealing for 30 minutes in $N_{2}$ ambient and characterized through XRD, sheet resistance, and C-V measurement(Cu($1000{\AA}$)/TaN($50{\AA}$)/$SiO_{2}$($2000{\AA}$)/Si capacitor fabricated), which prove the TaN film maintains the barrier properties Cu below $400^{\circ}C$.

• Advances in pediatric surgery
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• 제7권2호
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• pp.95-104
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• 2001

Biliary atresia (BA) is very difficult to distinguish from neonatal hepatitis (NH) and its prognosis depends on the age at the time of Kasai operation. Therefore early differentiation between these two conditions is very important. Although various clinical and laboratory tests have been reported to differentiate between them, they are still of limited value. From 1980 to 1999, forty-five infants were referred to our pediatric surgical unit for operation for suspected BA. Eight patients underwent Kasai operation immediately because of late diagnosis. These were excluded from the study. The clinical history, physical findings. radiologic and laboratory examinations of 37 cases were analyzed retrospectively. The average age of BA (n=20) was $55.1{\pm}16.7$ days, and that of NH (n=17) was $55.8{\pm}15.6$ days. The sex ratio of BA was 13:7, and that of NH was 14:3. All the patients had obstructive jaundice and acholic stool except 4 BA and 6 NH patients. Acholic stool with yellow component was more frequent in NH. Onset of jaundice was within 2 weeks after birth in 85 % of BA, and in 65% of NH. The onset of acholic stool was within 2 weeks after birth in 60 % of BA, and in 23.5 % of NH. The duration of jaundice and acholic stool of BA were $50.9{\pm}16.6$ days and $41.3{\pm}18.4$ days and those of NH were $40.1{\pm}23.1$ days and $26.6{\pm}25.4$ days respectively. The ultrasonogram and hepatobiliary scan were useful, but not a definitively reliable method for the differentiation of these two diseases. There was no difference in laboratory data. Seventeen cases had NH among 45 referred cases for Kasai operation with the clinical impression of BA, and 4 cases of 17 NH cases needed to be explored to rule out BA. In conclusion. false positive rate of clinical impression of BA was 37.8 %. and negative exploration rate was 8.9 %, Therefore. careful clinical observation for 1-2 weeks by an experienced pediatric surgeon was very important to avoid unnecessary operation to rule out NH up to the age of 8 - 10 weeks. so long as the stool had yellow component.