• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.713-719
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• 2016

The NOx conversion properties of Mn-Cu-$TiO_2$ and $V_2O_5$/$TiO_2$ catalysts were studied for the selective catalytic reduction (SCR) of NOx with ammonia. The performance of the catalysts was investigated in terms of their $NOx$ conversion activity as a function of the reaction temperature and space velocity. The activity of the Mn-Cu-$TiO_2$ catalyst decreased with increasing reaction temperature and space velocity. However, the activity of the $V_2O_5$/$TiO_2$ catalyst increased with increasing reaction temperature. High activity of the Mn-Cu-$TiO_2$ catalyst was observed at temperatures below $200^{\circ}C$. H2-TPR and XPS analyses were conducted to explain these results. It was found that the activity of the Mn-Cu-$TiO_2$ catalyst was influenced by the thermal shock caused by the change of the initial reaction temperature, whereas the $V_2O_5$/$TiO_2$ catalyst was not affected by the initial reaction temperature. In the case of catalyst C, the $NO_x$ conversion efficiency decreased with increasing space velocity. The decrease in the $NO_x$ conversion efficiency with increasing space velocity was much less for catalyst D than for catalyst C.

• Tuberculosis and Respiratory Diseases
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• v.45 no.6
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• pp.1223-1235
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• 1998

Background and Objective : Although prone positioning has been reported to improve gas exchange, prone positioning alone does not seem to be sufficient to increase systemic oxygen transport in an acute lung injury. The objective of this study was to investigate whether the combined therapy of low dose nitric oxide (NO) inhalation and prone positioning has an additive effect on the oxygenation and hemodynamics in patients with severe ARDS. Patients and Methods : Twelve patients with ARDS were included. Prone positioning alone, later combined with nitric oxide inhalation (5~10 ppm) from the supine position (baseline) were performed with serial measurement of gas exchange, respiratory mechanics and hemodynamic at sequential time points. The patient was regarded as a responder to prone positioning if an increase in $PaO_2/FiO_2$ of more than 20 mm Hg at 30 min or 120 min intervals after prone positioning was observed compared to that of the baseline. The same criterion was applied during nitric oxide inhalation. Results : Eight patients (66.5%) responded to prone positioning and ten patients (83.3%) including the eight just mentioned responded to the addition of NO inhalation. The $AaDO_2$ level also decreased promptly with the combination of prone positioning and NO inhalation compared to that of prone positioning alone ($191{\pm}109$ mm Hg vs. $256{\pm}137$ mm Hg, P<0.05). Hemodynamic parameters and lung compliance did not change significantly during prone positioning only. Following the addition of NO inhalation to prone positioning, the mean pulmonary artery pressure and pulmonary artery occlusion pressure decreased and cardiac output, stroke volume and oxygen delivery increased (P < 0.05) compared to those of prone 120 min. Conclusion : These findings indicate that NO inhalation would provide additional improvement in oxygenation and oxygen transport to mechanically ventilated patients with ARDS who are in a prone position.

• Journal of Chest Surgery
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• v.32 no.2
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• pp.138-143
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• 1999

Background: The endothelium-dependent vasorelaxation has been largely accounted for by the release of nitric oxide (NO). Three distinct isoforms of NO synthases (NOS) have been characterized, i.e., brain(bNOS), inducible (iNOS), and endothelial constitutive (ecNOS). Although hypertension hasbeen associated with a vascular endothelial dysfunction, changes in the vascular expression of NOS isoforms have not been established. The present study was aimed at exploring the vascular expression of NOS isozymes in hypertension. Material and Method: Two-kidney, one clip (2K1C) and deoxycorticosterone acetate (DOCA)-salt hypertension were induced in rats. The expression of different NOS isozymes in the thoracic aorta was determined by Western blot analysis. The vascular tissue contents of nitrites were measured by colorimetric assay. Result: Arterial blood pressure was significantly higher in experimental groups of 2K1C and DOCA-salt rats compared with their corresponding control rats. The vascular expression of bNOS as well as that of ecNOS was decreased in both models of hypertension. iNOS was not changed in DOCA-salt hypertension, but was also decreased in 2K1C hypertension. The vascular contents of nitrites were significantly decreased in DOCA-salt as well as in 2K1C hypertension. Conclusion: These results suggest that 2K1C and DOCA-salt hypertension are associated with decreases in the vascular expression of NOS isozymes and nitrite contents.

• Journal of the Korean Chemical Society
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• v.46 no.1
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• pp.14-18
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• 2002

It is shown that one-electron reduction of nitric oxide (NO) to nitroxyl anion $(NO^-)$ can be accelerated by vibrational energy. Potential energy surfaces of NO and $NO^-$ reveal that the vertical transition between them has favorable energetics for vibrationally excited molecule. Also, Franck-Condon factors between NO and $NO^-$ vibrational wave functions are calculated. It shows that the number of open channels increases with increased vibrational energy. These results mean that we can control the rate of reduction of NO to $NO^-$ by radiating an appropriate light.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.237-243
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• 2011

As the effluent quality standard of the municipal wastewater treatment plant (MWTP) has been strengthened, the treatment of the recycle water containing high concentration of ammonium nitrogen has been considered as one of retrofit methods for upgrading the exising MWTPs. In this study, nitritation, economic nitrogen removal process, was induced by laboratory-scale reactor at the $35^{\circ}C$, $20^{\circ}C$, and $10^{\circ}C$ temperature conditions using anaerobic digester supernatant. The stable nitritation was achieved over $20^{\circ}C$, but nitrification was induced at $10^{\circ}C$. It means that the nitritation was affected by SRT and temperature. SRT, demanded for nitritation, is changed according to the temperature. Therefore, it is considered that SRT and temperature are important factors in nitritation. Also, it is approved that inducing the ammonium nitrogen removal and the nitritation are more beneficial over $20^{\circ}C$. The conclusion of this study can be used for the important basic reference when nitritation process is applied for MWTPs.

• Journal of Life Science
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• v.19 no.5
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• pp.625-632
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• 2009

The purpose of this study was to examine the effect of exercise training on nitric oxide (NO) levels, mean arterial pressure (MAP), blood pressure (BP), and heart rate (HR) in college students. 5 subjects were randomly assigned to two experimental groups; an aerobic training group (ATG) and a resistance training group (RTG). In aerobic training, based on measured maximum oxygen consumption rate, 70% exercise intensity was applied and conducted for 60 min. In resistance training, 70% of 1-RM was performed for 90 min. Blood sampling was conducted 3 times during resting state, post-exercise, and after 30 minutes of recovery. The results are as followed. For the post training values of $VO_2max$, % body fat and MAP, there were significant differences in the ATG compared to pre training (p<0.05). However, there were no differences in the RTG between pre and post training. NO increased post training, during rest and at the end of exercise compared to pre training in the ATG (p<0.05). Also, the HR decreased in post training at the end of exercise (p<0.05), however, there were no significant differences in SBP and DBP between pre and post training in the ATG. The HR, SBP and DBP did not change at all in post training compared to pre training in the RTG. In conclusion, an increase in the production of Nitric Oxide (NO) concentration and $VO_2max$, decrease of body fat% and physiological variables (HR, BP, MAP) were shown to be more effective in aerobic training (AT) than resistance training (RT).

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.700-704
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• 2008

Nitrite and free ammonia have been known as substrate inhibitors in anaerobic ammonium oxidation. To reduce inhibitory effect of these substrates, the NH$_3$-N/NO$_2$-N ratio in the influent could be properly controlled in anaerobic ammonium oxidation process. Five kinds of NH$_3$-N/NO$_2$-N ratio were assayed in batch to find optimum NH$_3$-N/NO$_2$-N ratio, curtailing substrate inhibition. As the results of batch test, the highest T-N removal efficiency of 88% was obtained at 1.00 : 1.30 of NH$_3$-N/NO$_2$-N ratio. In addition, rate constants for ammonium and nitrite in zero-order kinetics were found to be the highest values as 7.66 mg/L$\cdot$hr and 11.89 mg/L$\cdot$hr at 1.00 : 1.30 ratio, respectively. However, as for the specific anammox activity, the ratio of NH$_3$-N/NO$_2$-N ratio was recommended as 1 : 1.15 which can maintain the highest SAA during continuous operation and preclude the accumulation of nitrite in the reactor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.260-260
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• 2009

초박형 절연막은 현재 다양한 전자소자의 제작과 향상을 위하여 활용되고 있으며, 일반적인 화학 기상 증착 방법으로는 균일도를 확보하기 어려운 문제점을 가지고 있다. 본 논문에서는 디스플레이의 구동소자로 활용되는 박막 트랜지스터의 특성 향상과 비휘발성 메모리 소자의 터널링 박막에 응용하기 위하여 초박형 실리콘 옥시나이트라이드 박막의 증착과 이의 특성을 분석하였다. 실리콘 옥시나이트라이드 박막은 실리콘 산화막에 질소가 주입되어 있는 형태로 실리콘 산화막과 실리콘 계면상에 존재하는 질소는 터널링 전류와 결함 형성을 감소시키며, bulk 내에 존재하는 질소는 단일 실리콘 산화막에 비해 더 두꺼운 박막을 커패시턴스의 감소없이 이용할 수 있는 장점이 있다. 플라즈마 처리 기법을 이용하였을 경우에는 초박형의 균일한 박막을 얻을 수 있으며, 본 연구에서는 이산화질소 플라즈마를 이용하여 활성화된 질소 및 산소 라디칼들이 실리콘 계면을 개질하여 초박형 실리콘 옥시나이트라이드 박막을 형성활 수 있다. 플라즈마 처리 시간과 RF power의 변화에 따라 형성된 실리콘 옥시나이트라이드 박막의 두께 및 광학적 특성은 엘립소미터를 통하여 분석하였으며, 전기적인 특성은 금속-절연막-실리콘의 MIS 구조를 형성하여 커패시턴스-전압 곡선과 전류-전압 곡선을 사용하여 평가하였다. 이산화질소 플라즈마 처리 방법을 사용한 실리콘 옥시나이트라이드 박막을 log-log 스케일로 시간과 박막 두께의 함수로 전환해보면 선형적인 증가를 나타내며, 이는 초기적으로 증착률이 높고 시간이 지남에 따라 두께 증가가 포화상태에 도달함을 확인할 수 있다. 실리콘 옥시나이트라이드 박막은 초기적으로 산소의 함유량이 많은 형태의 박막으로 구성되며, 시간의 증가에 따라서 질소의 함유량이 증가하여 굴절률이 높고 더욱 치밀한 형태의 박막이 형성되었으며, 이는 시간의 증가에 따라 플라즈마 챔버 내에 존재하는 활성종들은 실리콘 박막의 개질을 통한 실리콘 옥시나이트라이드 박막의 두께 증가에 기여하기 보다는 형성된 박막의 내부적인 성분 변화에 기여하게 된다. 이산화질소 플라즈마 처리 시간의 변화에 따라 형성된 박막의 정기적인 특성의 경우, 2.3 nm 이상의 실리콘 옥시나이트라이드 박막을 가진 MIS 구조에서 accumulation과 inversion의 특성이 명확하게 나타남을 확인할 수 있다. 아산화질소 플라즈마 처리 시간이 짧은 실리콘 옥시나이트라이드 박막의 경우 전압의 변화에 따라 공핍영역에서의 기울기가 현저히 감소하며 이는 플라즈마에 의한 계면 손상으로 계면결합 전하량이 증가에 기인한 것으로 판단된다. 또한, 전류-전압 곡선을 활용하여 측정한 터널링 메카니즘은 2.3 nm 이하의 두께를 가진 실리콘 옥시나이트라이드 박막은 직접 터널링이 주도하며, 2.7 nm 이상의 두께를 가진 실리콘 옥시나이트라이드 박막은 F-N 터널링이 주도하고 있음을 확인할 수 있다. 즉, 2.5 nm 두께를 경계로 하여 실리콘 옥시나이트라이드 박막의 터널링 메카니즘이 변화함을 확인할 수 있다. 결론적으로 2.3 nm 이상의 두께를 가진 실리콘 옥시나이트라이드 박막에서 전기적인 안정성을 확보할수 있어 박막트랜지스터의 절연막으로 활용이 가능하며 2.5 nm 두께를 경계로 터널링 메커니즘이 변화하는 특성을 이용하여 비휘발성 메모리 소자 제작시 전하 주입 및 기억 유지 특성을 확보를 위한 실리콘 옥시나이트라이드 터널링 박막을 효과적으로 선택하여 활용할 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.516-519
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• 1999

스위칭 전원에 사용되는 Mn-Zn 페라이트에 대항하는 고성능화의 요구에 부응하기 위해 그 중요한 요인이 되는 기수가 다른 Mn 산화물에 착목하여 그것들을 이용 제작한 Mn-Zn 페라이트의 자기특성 및 결정구조를 정밀하게 조사함과 동시에 그것들의 상관성을 검토하였다. Mn-Zn 페라이트의 소성 분위기의 변경방식은 소성개시에서 종료시까지 질소 분위기, 냉각시부터 질소분위기로 변경, 소성 개시에서 종료시까지 대기중 소성 세가지를 실험하였고, 소성 온도는 115$0^{\circ}C$, 120$0^{\circ}C$, 125$0^{\circ}C$ 130$0^{\circ}C$ 135$0^{\circ}C$ 및 140$0^{\circ}C$의 6종류의 시료를 제작하였다. 이 결과는 Mn-Zn 페라이트의 소성 분위기 및 온도 최적화는 승온 및 온도 유지 단계에서는 대기중으로, 냉각단계에서는 질소가스 분위기로 치환한 것과 소성 온도는 120$0^{\circ}C$ 이다. 이 분위기에서 Mn-Zn 페라이트를 가수를 다르게 하여 시료의 투자율 및 주파수 특성, 코아로스 주파수 의존성, 코아로스 주파수로 나눈값의 주파수 의존성, 스피넬 구조(311)의 면에서의 회절픽, 자화의 온도 의존성을 분석하였다. 이 결과는 Mn$_3$O$_4$를 출발원료로 사용한 Mn-Zn 페라이트가 투자율 및 한계 주파수 모두 뛰어난 특성을 나타내었다.

• Journal of the Korean Vacuum Society
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• v.3 no.3
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• pp.322-330
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• 1994

다결정실리콘 위에 저압 화학 증착법으로 비정질 WSix를 증착시킨 후에 질소 분위기, 87$0^{\circ}C$ 온 도에서 2시간 동안 열처리를 실시하여 결정화를 이룩한 다음 표면의 산화막을 희석된 불산용액으로 제 거한 후 산화를 실시하면 이상산화막이 형성이 되었다. 이와 같은 이상산화막 형성은 산화 공정전에 P 또는 As 이온 주입을 실시함으로써 억제되고 있었으며 P이온 주입 처리가 As 이온조입보다 이상산화 막 발생 억제에 보다 효율적임이 확인되었다. P이온 주입처리가 보다 효과적인 것은 산화시 산화막내에 형성되는 P2O5 가 산화막의 용융점을 크게 낮추어 양질의 산화막을 형성하는 데 기인하는 것으로 여겨 진다. 마지막으로 이온주입 처리에 의하여 비정질화된 텅스텐 실리사이드 표묘의 산화 기구에 대하여 제안하였다.