• Korean Chemical Engineering Research
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• 제52권4호
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• pp.443-450
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• 2014

지르코니아를 고정한 실리카($ZrO_2-SiO_2$)와 망가니즈 산화물($MnO_x$)에 백금을 담지하여 제조한 촉매에서 수소에 의한 일산화질소의 선택적 촉매 환원($H_2$-SCR) 반응을 조사하였다. $Pt-MnO_x$ 촉매에서는 NO 전환율이 낮으며, $N_2O$와 $NO_2$ 생성이 억제되었다. 반면, $Pt/ZrO_2-SiO_2$ 촉매에서는 NO 전환율이 높지만, $100{\sim}150^{\circ}C$에서는 $N_2O$가, $200{\sim}300^{\circ}C$에서는 온도가 높아지면 $NO_2$ 수율이 높아져, $N_2$ 수율이 낮았다. $ZrO_2-SiO_2$에 $MnO_x$와 백금을 같이 담지한 $Pt-MnO_x/ZrO_2-SiO_2$촉매에서는 $100{\sim}150^{\circ}C$에서 이들 성분의 상승작용으로 $N_2$ 수율이 조금 높아졌다. 이들 촉매에서 표면 조성, 산화 상태, 산성도를 조사하고, NO가 흡착되어 수소와 반응하는 과정의 IR 스펙트럼을 그렸다. NO의 $H_2$-SCR 반응에서 전환율과 생성물 수율을 촉매 구성 성분의 촉매작용과 연계지어 고찰하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.130.1-130.1
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• 2013

We made attempts to improve photocatalytic activity of $TiO_2$ nanoparticles under visible light exposure by combining two additional treatments. N-doping of $TiO_2$ by ammonia gas treatment at $600^{\circ}C$ increased absorbance of visible light. By coating thin film of polydimethylsiloxane (PDMS), and subsequent vacuum-annealing at $800^{\circ}C$, $TiO_2$, became more hydrophilic, thereby enhancing photocatalytic activity of $TiO_2$. Four types of $TiO_2$ samples were prepared, bare-$TiO_2$, hydrophilic-modified $TiO_2$ ($h-PDMS/TiO_2$), N-doped $TiO_2$ ($N/TiO_2$) and hydrophilic-modified and N-doped $TiO_2$ ($h-PDMS/N/TiO_2$). Adsorption capability was evaluated under dark condition and photocatalytic activity of $TiO_2$ was evaluated by photodegradation of MB under blue LED (400 nm< ${\lambda}$) irradiation. N-doping on $TiO_2$ was characterized using XPS and hydrophilic modification of $TiO_2$ surface was analyzed by FT-IR spectrometer. It was found that N-doping and hydrophilic modification both had positive effect on enhancing adsorption capability and photocatalytic activity of $TiO_2$ at the same time. Particularly, N-doping enhanced visible light absorption of $TiO_2$, whereas hydrophilic surface modification increased MB adsorption capacity. By combining these two strategies, photocatalytic acitivity under visible light irradiation became the sum of individual effects of N-doping and hydrophilic modification.

• 한국자기학회지
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• 제13권3호
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• pp.121-126
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• 2003

(N $i_{0.2}$C $u_{0.2}$Z $n_{0.6}$)$_{1.085}$(F $e_2$ $O_3$)$_{0.915}$의 기본 조성에 첨가제 Sn $O_2$, CaO 첨가량과 ferrite의 공정을 변화시켜 시편의 전자기적 특성 및 미세구조를 조사하였다. 첨가제에 따른 입자크기의 변화는 거의 없었다. (N $i_{0.2}$C $u_{0.2}$Z $n_{0.6}$)$_{1.085}$(F $e_2$ $O_3$)$_{0.915}$을 소결시 1300 $^{\circ}C$에서 소결하는 것보다 1150 $^{\circ}C$에서 소결한 소결체의 손실이 더욱 적었다. CaO만 첨가할 때 0.2 wt%가 소결밀도를 크게하여 손실을 줄여주는 첨가제로 사용 가능함을 확인하였다 Sn $O_2$차 Ca $O_2$함께 첨가시 SnO2$_2$ 0.06 wt%, CaO 0.4 wt%가 손실을 크게 줄여 주는 것으로 조사되었다.

• 대한화학회지
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• 제27권2호
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• pp.83-94
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• 1983

EHT calculation의 고유함수를 사용하여 $[M(II)O_3N_3]$ 및 $[Ni(II) O_2N_4]$ 형태착물[M(II) = Co(III), Ni(II) 및 Cu(II)]의 쌍극자 모멘트에 대한 cis 및 trans 구조의 영향을 고찰하였다. cis$[M(Ⅱ)O_3N_3]$ 형태착물의 계산한 쌍극자 모멘트가 trans착물의 계산한 쌍극자 모멘트 값보다 큰 값을 가지며 trans 착물의 쌍극자 모멘트 값이 실험치 범위안에 들었다. 그러나 $[Ni(II) O_2N_4]$ 착물의 경우 cis 착물의 쌍극자 모멘트 값이 실험치 범위안에 들었다. 이 결과는 $[Co(III)O_3N_3]$ 형태착물이 trans 구조, $[Ni(II) O_2N_4]$ 형태착물은 cis 구조를 가졌음을 암시하며 이는 실험결과와 일치한다. $[M(II)O_3N_3]$ 형태착물에서 세개의 두자리 (O-N)리간드가 금속이온에 배위되어 있으며 $[Ni(II) O_2N_4]$형태 착물에서는 두개의 세자리(O-N-N) 리간드가 Ni(II) 이온에 배위되어 있음).

• 한국환경농학회지
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• 제31권3호
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• pp.205-211
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• 2012

BACKGROUND: Generally, nitrogen (N) fertilization higher than the recommended dose is applied during vegetable cultivation to increase productivity. But higher N fertilization also increases the concentrations of nitrate ions and nitrous oxide in soil. In this experiment, the impact of N fertilization was studied on nitrous oxide ($N_2O$) emission to standardize the optimum fertilization level for minimizing $N_2O$ emission as well as increasing crop productivity. Herein, we developed $N_2O$ emission inventory for upland soil region during red pepper and Chinese milk vetch cultivation. METHODS AND RESULTS: Nitrogen fertilizers were applied at different rates to study their effect on $N_2O$ emission during red pepper and Chinese milk vetch cultivation. The gas samples were collected by static closed chamber method and $N_2O$ concentration was measured by gas chromatography. The total $N_2O$ flux was steadily increased due to increasing N fertilization level, though the overall pattern of $N_2O$ emission dynamics was same. Application of N fertilization higher than the recommended dose increased the values of both seasonal $N_2O$ flux (94.5% for Chinese cabbage and 30.7% for red pepper) and $N_2O$ emission per unit crop yield (77.9% for Chinese cabbage and 23.2% for red pepper). Nitrous oxide inventory revealed that the $N_2O$ emission due to unit amount of N application from short-duration vegetable field in fall (autumn) season (6.36 kg/ha) was almost 70% higher than that during summer season. CONCLUSION: Application of excess N-fertilizers increased seasonal $N_2O$ flux especially the $N_2O$ flux per unit yield during both Chinese cabbage and red pepper cultivation. This suggested that the higher N fertilization than the recommended dose actually facilitates $N_2O$ emission than boosting plant productivity. The $N_2O$ inventory for upland farming in temperate region like Korea revealed that $N_2O$ flux due to unit amount of N-fertilizer application for Chinese cabbage in fall (autumn) season was comparatively higher than that of summer vegetables like red pepper. Therefore, the judicious N fertilization following recommended dose is required to suppress $N_2O$ emission with high vegetable productivity in upland soils.

• Bulletin of the Korean Chemical Society
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• 제23권6호
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• pp.851-856
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• 2002

The Reaction of S-methyl-S-cysteine(L-Smc) with racemic $s-cis-[Co(demba)Cl_2]-1$ (Hydmedba = $NN'-dimethylethylenediamine-NN'-di-\alpha-butyric$, acid) yields ${\Delta}$-s-cis-[Co(dmedba)(L-Smc)] 2 with N, O-chelation. Oxidation of sulfur of 2 with $H_2O_2$ in a 1 : 1 mole ratio gives ${\Delta}$-s-cis[Co(dmedba)(L-S(O)mc)] 3 having an uncoordinated sulfenate group. Oxidation of sulfur of L-Sm with $H_2O_2in$ a 1: 1 mole ratio produces S-methyl-L-cysteinesulfenate (L-S(O)me) 5. Direct reaction of 1 with 5 in basic medium gives an N.O-chelated ${\Delta}$s-cis[Co(dmedba)(L-S(O)mc)-N.O], which turmed out be same as obtained by oxidation of 2, while an N, S-chelated ${\Delta}$-s-cis-[Co(dmedba)(S-S(O)mc)-N,O] complex 4 is obtained in acidic medium from the reaction of 1 with 5. This is one of the rare $[$Co^{III}$(N_2O_2-type$ ligand)(amino acid)] type complex preparations, where the reaction conditions determine which mode of N, O and N, S caelation modes is favored.

• 청정기술
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• 제29권2호
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• pp.126-134
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• 2023

직접촉매분해기술은 반도체 및 디스플레이 산업에서 아산화질소(N₂O)의 배출을 완화할 수 있는 유망한 기술이다. 본 연구는 7대 온실가스 중에 하나인 N₂O 직접촉매분해를 위한 γ-Al₂O₃ 촉매에 관한 것이다. 실험에 사용한 γ-Al₂O₃ 촉매는 뵘석 분말을 사용하여 압출 성형하여 제조하였으며, 반응은 직경 약 5 mm 크기로 분쇄한 촉매를 직경 25.4 mm (1인치) 반응기를 사용하여 수행하였다. N₂O 농도는 약 1%가 되도록 공급하였으며, 온도는 550-750 ℃, 압력은 상압, GHSV는 1800-2000 h-1에서 촉매반응 특성을 확인하였다. 분위기 가스로는 질소, 공기 그리고 공기+수분을 공급하여 N₂O 분해 특성과 산소의 영향 및 스팀의 영향을 확인하였다. 촉매 내구성은 N₂ 분위기에서 수행하였는데, 700 ℃에서 350 시간 동안 연속 운전을 통해 확인하였다. 실험결과 불활성 분위기(N₂)일 경우 700 ℃에서 N₂O 분해율이 100%에 가까운 수준까지 도달함을 확인하였고, 공기와 수분을 공급할 경우 분해율이 낮아짐을 확인하였다. 내구성 실험 결과 350 시간동안 촉매성능저하는 없었다. 따라서 뵘석 분말로 제조한 γ-Al₂O₃ 촉매는 N₂O 분해 특성에 우수할 뿐만 아니라 내구성 또한 우수하여 전자 산업을 비롯하여 질산제조공정 등 산소와 수분이 존재하는 경우에도 적용 가능할 것으로 기대한다.

• 한국정보통신학회논문지
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• 제13권11호
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• pp.2385-2390
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• 2009

본 연구에서는 C-축 우선 배향 특성을 가지는 N-doped ZnO 박막을 증착하고 그 미세구조의 특성을 분석 비교하였다. ZnO박막은 $N_2O$ 가스 분위기에서 RF reactive magnetron sputtering 시스템을 사용하여 p-Si(100) 웨이퍼 위에 증착되었다. $N_2O$ 가스는 N doping source로 사용되었으며, 전체 가스 유량에 대한 $N_2O$ 가스의 비율 $N_2O/(N_2O+Ar)$과 증착 전력을 증착의 주요 공정 변수로 선택하여 다양한 가스 비율과 증착 전력에 대한 박막의 미세 구조 특성을 비교 분석하였다. 특히, Auger electron spectroscopy (AES)를 이용하여 ZnO 박막 내에 들어가 존재하는 불순물 N의 수직분포를 분석하였고, 여러 가지 증착 조건에서 제작된 ZnO 박막의 표면형상 및 미세구조 특성을 Scanning Electron Microscope (SEM)를 이용하여 분석하였다.

• 한국대기환경학회지
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• 제19권5호
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• pp.529-540
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• 2003

A closed chamber system was used for measuring $N_2$0 fluxes from an agriculturally managed upland soil in Kunsan during the growing season from May to July 2002. It is known that soil is one dominant source of atmospheric $N_2$O, contributing to about 57% (9 Tg y $^{-1}$ ) of the total annual global emission. Hence, its increasing emissions and concentrations are largely associated with agricultural activities. In order to elucidate characteristics of soil nitrogen emissions from intensively managed agricultural soils and to understand the roles of soil parameters (soil moisture, soil pH, soil temperature, and soil nitrogen) in the gas emission, $N_2$O soil emissions were measured at every hour during the experimental period (21 days). Soil $N_2$O fluxes were calculated based on changes of $N_2$O concentrations measured inside a closed chamber at every hour. The analysis of $N_2$O was made by using a Gas Chromatography (equipped with Electron Capture Detector). Soil parameters at sampling plots were also analyzed. Monthly averaged $N_2$O fluxes during May, June, and July were 0.14, 0.05, and 0.13 mg-$N_2$O m$^{-2}$ h$^{-1}$ , respectively. Soil temperature and soil pH did not significantly vary over the experimental period; soil temperatures ranged from 12∼$25^{\circ}C$, and soil pH ranged 4.56∼4.75. However, soil moisture varied significantly from 32% to 56% in WFPS. Relationships between soil parameters and $N_2$O fluxes exhibited positive linear relationships. Strong positive correlation ($R^2$ = 0.57, P< 0.0001) was found between $N_2$O flux and sil moisture. It suggests that soil moisture has affected strongly soil $N_2$O emissions during the experimental periods, while other parameters have remained relatively at constant levels. $N_2$O flux from agricultural soils was significant and should be taken account for the national emission inventory.

• 한국전기전자재료학회논문지
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• 제25권1호
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• pp.44-47
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• 2012

The $TiO_2/Si_3N_4/Ag/Si_3N_4/TiO_2$ multi layered structure was designed for the possible application of transparent electrodes in PDP (Plasma Display Panel). Multi layered film was deposited on a glass substrate at room temperature by DC/RF magnetron sputtering system and EMP (Essential Macleod Program) was adopted to optimize the optical characteristics of film. During the deposition process, the Ag layer in $TiO_2/Ag/TiO_2$ became heavily oxidized and the filter characteristic was degraded easily. In thus study, Si3N4 layer was used as a diffusion buffer layer between $TiO_2$ and Ag. in order to prevent the oxidation of Ag layer in $TiO_2/Si_3N_4/Ag/Si_3N_4/TiO_2$ structure. It was confirmed that $Si_3N_4$ layer is one of candidate materials acting as diffusin barrier between $TiO_2/Ag/TiO_2$.