• Tuberculosis and Respiratory Diseases
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• v.45 no.6
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• pp.1265-1276
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• 1998

Background : Nitric oxide(NO) is an endogenously produced free radical that plays an important role in regulating vascular tone, inhibition of platelet aggregation and white blood cell adhesion to endothelial cells, and host defense against infection. The highly reactive nature of NO with oxygen radicals suggests that it may either promote or reduce oxidant-induced cell injury in several biological pathways. Oxidant injury and interactions between pulmonary vascular endothelium and leukocytes are important in the pathogenesis of acute lung injury, including acute respiratory distress syndrome(ARDS). In ARDS, therapeutic administration of NO is a clinical condition providing exogenous NO in oxidant-induced endothelial injury. The role of exogenous NO from NO donor or the suppression of endogenous NO production was evaluated in oxidant-induced endothelial injury. Method : The oxidant injury in cultured rat lung microvascular endothelial cells(RLMVC) was induced by hydrogen peroxide generated from glucose oxidase(GO). Cell injury was evaluated by $^{51}$chromium($^{51}Cr$) release technique. NO donor, such as S-nitroso-N-acetylpenicillamine(SNAP) or sodium nitroprusside(SNP), was added to the endothelial cells as a source of exogenous NO. Endogenous production of NO was suppressed with N-monomethyl-L-arginine(L-NMMA) which is an NO synthase inhibitor. L-NMMA was also used in increased endogenous NO production induced by combined stimulation with interferon-$\gamma$(INF-$\gamma$), tumor necrosis factor-$\alpha$(TNF-$\alpha$), and lipopolysaccharide(LPS). NO generation from NO donor or from the endothelial cells was evaluated by measuring nitrite concentration. Result : $^{51}Cr$ release was $8.7{\pm}0.5%$ in GO 5 mU/ml, $14.4{\pm}2.9%$ in GO 10 mU/ml, $32.3{\pm}2.9%$ in GO 15 mU/ml, $55.5{\pm}0.3%$ in GO 20 mU/ml and $67.8{\pm}0.9%$ in GO 30 mU/ml ; it was significantly increased in GO 15 mU/ml or higher concentrations when compared with $9.6{\pm}0.7%$ in control(p < 0.05; n=6). L-NMMA(0.5 mM) did not affect the $^{51}Cr$ release by GO. Nitrite concentration was increased to $3.9{\pm}0.3\;{\mu}M$ in culture media of RLMVC treated with INF-$\gamma$ (500 U/ml), TNF-$\alpha$(150 U/ml) and LPS($1\;{\mu}g/ml$) for 24 hours ; it was significantly suppressed by the addition of L-NMMA. The presence of L-NMMA did not affect $^{51}Cr$ release induced by GO in RLMVC pretreated with INF-$\gamma$, TNF-$\alpha$ and LPS. The increase of $^{51}Cr$ release with GO(20 mU/ml) was prevented completely by adding 100 ${\mu}M$ SNAP. But the add of SNP, potassium ferrocyanate or potassium ferricyanate did not protect the oxidant injury. Nitrite accumulation was $23{\pm}1.0\;{\mu}M$ from 100 ${\mu}M$ SNAP at 4 hours in phenol red free Hanks' balanced salt solution. But nitrite was not detectable from SNP upto 1 mM The presence of SNAP did not affect the time dependent generation of hydrogen peroxide by GO in phenol red free Hanks' balanced salt solution. Conclusion : Hydrogen peroxide generated by GO causes oxidant injury in RLMVC. Exogenous NO from NO donor prevents oxidant injury, and the protective effect may be related to the ability to release NO. These results suggest that the exogenous NO may be protective on oxidant injury to the endothelium.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.147-155
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• 2016

Pulp made from sugarcane bagasse (SCB) was bleached in element chlorine free (ECF) sequence. The peroxide bleaching process for the final bleaching process has been introduced in order to reduce the use of chlorine dioxide. Prior to peroxide bleaching, different chelating chemicals were applied. When 4.5% of the total chlorine dioxide was used, bleached SCB pulp using additional DTPA chelate stage (DEDQP) resulted in 87.0% of the ISO brightness. However, bleached pulp using simultaneous stage of DTPA chelate and chlorine dioxide (DE(DQ)P) was reached at 83.9% of the ISO brightness. The viscosity of DEDQP bleached pulp was 25.6 cPs, and the one of DE(DQ)P bleached pulp was 21.9 cPs. Decreasing of chelate effect by chlorine dioxide led to a decrease in the final brightness and a lower viscosity. But simultaneous stage of EDTA chelate and chlorine dioxide (DE(DQ)P) led to higher final brightness (87.0% ISO) and higher viscosity (25.8 cPs) than those of the $DEDQ_{EDTA}P$ bleached pulp (86.4% ISO, 25.2 cPs).

• Journal of the Korean Electrochemical Society
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• v.4 no.4
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• pp.172-175
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• 2001

Nanophase catalyst layer for direct methanol fuel cell has been fabricated by magnetron sputtering method. Catalyst metal targets and carbon were sputtered simultaneously on the Nafion membrane surface at abnormally higher gas (Ar/He mixture) pressure than that of normal thin film processing. They could be coated as a novel structure of catalyst layer containing porous PtRu or Pt and carbon particles both in nanometer range. Membrane electrode assembly made with this layer led to a reduction of the catalyst loading. At the catalyst loading of 1.5mg $PtRu/cm^2$ for anode and 1mg $Pt/cm^2$ for cathode, it could provide $45 mW/cm^2$ in the operation at 2 M methanol, 1 Bar Air at 80"C. It is more than $30\%$ increase of the power density performance at the same level of catalyst loading by conventional method. This was realized due to the ultra fine particle sizes and a large fraction of the atoms lie on the grain boundaries of nanophase catalyst layer and they played an important role of fast catalyst reaction kinetics and more efficient fuel path. Commercialization of direct methanol fuel cell for portable electronic devices is anticipated by the further development of such design.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.507-511
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• 2005

울돌목은 조류발전의 세계적인 최적지로 꼽히고 있으며 서해와 남해의 점이 지대로서 조류에 의해 해양 생물 군집의 대량 이동이 빈번한 곳이라 할 수 있다. 조류 발전 시설인 터빈의 가동은 물리적인 충격에 의해 해양 생물의 생태-생리 반응에 영향을 미칠 가능성이 있다. 네트를 이용한 1차 조사에서 터빈 가동에 의한 동물플랑크톤의 순 사망률은 $44.3\%$로 나타났다. 1차 조사 이 후 다이아프램 펌프를 이용한 조사 결과 중 출현 개체수가 높았던 조사에서 전체 동물플랑크톤의 순 사망률은 각각 $7.3\%,\;5.8\%$를 나타내었고, 요각류는 각각 $4.4\%,\;5.2\%$를 나타냈다. 물리적인 충격을 인위적으로 가한 실험에서 스트레스를 받은 요각류 Acartia hongi의 알 생산은 스트레스를 받지 않은 것보다 $1.8\~2.3$배 낮은 경향을 보였다. 본 조사에서 동물플랑크톤이 낮은 사망률을 보골 이유는 작은 크기의 생물이 우점하였기 때문이며 조사 결과에서 몸체가 비교적 단단하고 크기가 작은 요각류는 상대적으로 약한 부유유생보다 높은 생존율을 보였다. 울돌목 조사 해역에서 출현한 동물플랑크톤은 크기가 작아 터빈의 물리적인 충격에 의한 사망률은 낮을 수 있으나 순간적으로 강한 스트레스를 받는다면 재생산을 포함한 생리활동이 저하될 수 있음을 보였다. 네트 및 펌프를 이용한 조사 결과에서 네트에 의한 채집은 터빈의 영향뿐만 아니라 빠른 유속으로 인하여 네트가 받는 압력에 의해 생물체가 손상되는 양상이 높아 사망률이 높았던 것으로 보인다. 그러나 다이아프램 펌프는 생물 채집 시 오류를 최소화하는 장점은 있으나 채집의 장시간에 비해 매우 적은 생물량이 채집되는 단점을 보였다TEX>$96.5\%$에 미달하는 문제는 식물성 원료유로 제조한 고순도 바이오디젤과 혼합 사용하거나 감압 증류 공정을 통해 고농도의 폐식용유 바이오디젤을 제조하여 해결 가능하다. 대전시 신성동 소재의 음식점에서 수거한 폐식용유를 원료로 하여 생산한 바이오디젤의 차량 배출가스 실증 테스트 결과 경유 차량의 주 오염물질인 PM과 Soot 및 기타 오염물질의 배출량은 감소하였으나 NOx의 배출량은 약간 증가하는 것으로 나타났다구와 이해를 바탕으로 보존대책이 마련되어야 한다.되었다. 이런 모든 시편들을 각 탈염방법에 따라 탈염처리한 후 XRD와 SEM-EDS으로 분석한 결과 인철광과 침철광은 어떠한 변화도 보이지 않았고, 다만 적금광으로 동정된 시편만이 잔존하지 않았다. 철기 제작별 $Cl^-$ 이온 추출량과 탈염효과에 대한 비교 실험은 이온 크로마토그래피 분석 결과와 마찬가지로 단조 철제유물이 주조 철제보다 $Cl^-$ 이온을 많이 가지고 있었으며, 탈염 처리 후에는 $Cl^-$ 이온은 전혀 발견되지 않았다. 이상의 결과 $K_2CO_3$와 Sodium 용액은 탈염처리에서 가장 적합한 탈염처리 용액으로 알수가 있었으며 특히 어떠한 탈염 용액으로 유물을 처리한다 해도 철제유물에 생성된 부식물은 제거되지 않는다는 것을 알게 되었다. 따라서 보존처리자는 유물 표면의 부식 상태만을 보고 처리하기 보다는 철기제작물로 고려하여 처리하는 것이 필요하다. 또한 금속에 부식을 야기시키는 $Cl^-$ 이온과 부식물을 완전하게 제거하여 탈염처리를 하는 것이 유물 부식을 최대한 지연시킬 수 있는 것이라 생각된다.TEX>$88\%$)였다.(P=0.063). 결론: 본

• Resources Recycling
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• v.20 no.3
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• pp.28-39
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• 2011

This review investigated theoretical principals and practical application examples on recirculation system of soil washing-wastewater treatment-treated water recycling. As for technologies which have attempted to remediating metals-contaminated soil in and around country, there are reactive barriers, encapsulation, solidification/stabilization, soil washing, and phytoremediation. Among those, in particular, this review covers soil washing technology which physicochemically removes contaminants from soils. The major drawbacks of this technology are to generate a large amount of wastewater which contains contaminants complexed with ligands of washing solution and needs additional treatment process. To solve these problems, many chemical treatment methods have been developed as follows: precipitation/coprecipitation, membrane filtration, adsorption treatment, ion exchange, and electrokinetic treatment. In the last part of the review, recent research and field application cases on soil washing wastewater treatment and recycling were introduced. Based on these integrated technologies, it could be achieved to solve the problem of soil washing wastewater and to enhance cost effective process by reducing total water resources use in soil washing process.

• Restorative Dentistry and Endodontics
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• v.36 no.3
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• pp.196-202
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• 2011

Objectives: The aim of this study was to investigate levels of matrix metalloproteinase-8 (MMP-8) and substance P (SP) in root canal exudates during root canal treatment (RCT) of nonvital, painful teeth. Materials and Methods: Patients scheduled for nonsurgical RCT were prospectively selected; the study was performed after obtaining informed consent from the patients and was approved by the Institutional Review Board for Clinical Research of Gangnam Severance Hospital, Yonsei University (3-2008-0118). Canal exudates samples were collected using sterilized paper points from teeth scheduled for RCT across three different time periods. MMP-8 and SP levels were measured using enzyme-linked immunosorbent assay (ELISA). Data were analyzed using a mixed model analysis and the Pearson correlation analysis (p < 0.05). Results: MMP-8 and SP levels in GCF were decreased during RCT (p < 0.0001), and they showed a weak positive correlation to each other (p < 0.05). Patients' subjective pain levels and the response from percussion test were significantly related to SP level. Conclusions: This study demonstrated that periradicular inflammation endodontic origin can elevate SP and MMP-8 levels in root canal exudates. Interestingly, SP level of canal exudates showed a possibility of being used as an indicator of pain due to periapical pathosis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.112-118
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• 2018

In order to meet the strict emission regulations for internal combustion engines based on fossil fuel, the proportion of after-treatments for vehicles and vessels is gradually increasing. Diesel engines have high power, good fuel economy, and lower $CO_2$ emissions, and their market shares are increasing in commercial vehicles and passenger cars. However, NOx is generated in the localized high-temperature combustion regions, and particulate matter is formed in the zones of diffusion combustion. LNT and urea-SCR catalysts have been developed for after-treatment of the exhaust gas to reduce NOx in diesel vehicles. This study aims to improve the NOx reduction performance of Cu SCR catalyst, which is widely used in light, medium, and heavy-duty diesel engines. The de-NOx performance of $5Cu-2ZrO_2$/93Zeolyst(Si/Al=13.7) SCR catalyst was about 5-50% higher than that of $5Cu-2ZrO_2$/93Zeolite(Si/Al=2.9) at catalyst temperatures of $300^{\circ}C$ or higher. The zeolite had lower metal dispersion than zeolyst, and the reaction rate of the catalyst decreased as the average particle size increased. The $10Cu-2ZrO_2$/88Zeolyst catalyst loaded with 10wt% Cu had the highest NOx conversion rate of 40% at $200^{\circ}C$ and about 65% at $350^{\circ}C$. The ion exchange rate of Cu ions increased with that of Al, the crystalline compound of zeolite, and the de-NOx performance was improved by 20-40% compared to other catalysts.

• Journal of the Korean Vacuum Society
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• v.20 no.5
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• pp.361-366
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• 2011

An in-situ, real-time monitoring of GaN epilayers grown by low pressure metalorganic chemical vapor deposition system modified for spectral reflectance was performed. Reflectance spectrums from 190~861 nm were observed using p-polarized light with incident angle of $75^{\circ}$. All reflectance spectrums showed interference oscillation caused by multiple reflection within GaN epilayers, and the spectrum from GaN with low crystalline quality showed weak reflectance intensity and much low amplitude of the oscillation because many defects in GaN resulted in light scattering and absorption. Signal variation of reflected light which was selected around strong constructive wavelength range was also observed during $NH_3$ supplying and $NH_3$ cut-off. There was no significant change in signal intensity when $NH_3$ cut-off for 10 sec, but it showed higher intensity when $NH_3$ was cut off for over 30 sec and its intensity kept unchanged. This result indicates that GaN surface was N-terminated during $NH_3$ supplying but Ga-terminated during $NH_3$ cut-off because of high nitrogen equilibrium vapor pressure of GaN, and metallic Ga-terminated surface caused slightly higher reflectance intensity.

• Applied Biological Chemistry
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• v.35 no.6
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• pp.462-469
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• 1992

Two kinds of complement activating (anti-complementary) polysaccharides, which were expected to be immunomodulators were purified from Arecae Pericarpium (the pericarps of Areca catechu), and their action modes have been studied. The active polysaccharides, AC-2-IIIa and AC-2-IIIc from Arecae Pericarpium showed dose-dependent anti-complementary activities on $TCH_{50}$. The anti-complementary activities of AC-2-IIIa and AC-2-IIIc in metal ion-free condition were completely decreased in comparison with control whereas in case of $Ca^{2+}$-free condition, these activities were maintained, considerably. Also AC-2-IIIa and AC-2-IIIc showed relatively potent alternative complement pathway activities. Furthermore, after incubation of the normal human serum with polysaccharide of Arecae Pericarpium in the absence of $Ca^{2+}$ ion, a cleavage of C3 in the serum was found to have occurred through immunoelectrophoresis (IEP) with anti-human C3. Also, from the results of IEP using anti-human whole serum, the ratios of the height of 3rd peak to ${\alpha}2-M$ peak by AC-2-IIIa and AC-2-IIIc proved to be $1.50{\pm}0.04$ and $1.22{\pm}0.08$, respectively. These results indicate that the modes of complement activation by AC-2-IIIa and AC-2-IIIc from Arecae Pericarpium are via both the classical pathway and the alternative pathway.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.1-6
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• 2017

Stents are widely used as the most common method of treating coronary artery disease with implants in the form of a metal mesh. The blood flow is normalized by inserting a stent into the narrowed or clogged areas of the human body. In this study, the mechanical characteristics of a stent are investigated according to the variations of its design parameters by the Taguchi method and finite element analysis. A stent model of the Palmaz-Schatz type was used for the analysis. In the analysis, an elasto-plastic material model was adopted for the stent and a hyper-elastic model was used for the balloon. The main interest of this study is to investigate the effects of the design parameters which reduce the possibility of restenosis by adjusting the recoil amount. A Taguchi orthogonal array was constructed on the model of the stent. The thickness and length and angle of the slot were selected as the design parameters. The amounts of radial recoil and longitudinal recoil were calculated by finite element analysis. The statistical analysis using the Taguchi method showed that optimizing the shape of the stent could reduce the possibility of restenosis. The optimized shape showed improvements of recoil in the radial and longitudinal directions of ~1% and ~0.1%, respectively, compared to the default model.