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- 저자 : (O . Jung Kwon) (검색결과 673 건)
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Jung, S.W.,Park, J.,Kwon, O.B.,Kim, Y.J.,Keel, S.I.,Yun, J.H.,Lim, I.G. Butterworths [etc.] ; Elsevier Science Ltd 2014 Fuel Vol.136 No.-
The effects of CO<SUB>2</SUB> addition on the downstream interactions of H<SUB>2</SUB>-air and CO-air premixed flames were investigated. Flame stability diagrams mapping the extinction limits for various fuel concentrations as functions of the strain rate were developed for the downstream interactions between H<SUB>2</SUB>-air and CO-air premixed flames with 0-20% CO<SUB>2</SUB> addition. Of particular concern was the impact of the chemical reactions of the additional CO<SUB>2</SUB> on the flame extinction characteristics. The results showed that CO<SUB>2</SUB> addition suppressed the flammable regions appreciably and decreased the critical strain rate, opening up the lean extinction boundary. For highly stretched interacting flames, two flammable island regions on the maps were combined into one when 10% or 20% CO<SUB>2</SUB> was added to either the H<SUB>2</SUB>-air or CO-air premixed mixtures. The chemical reactions of the additional CO<SUB>2</SUB> were significant, especially for high strain rate flames, while the effect of the radiative heat loss of the additional CO<SUB>2</SUB> was minor, even for low strain rate flames. Such chemical reactions were determined by competition between the reaction steps for the consumption and production of HCO and the reverse reaction of CO+OH=CO<SUB>2</SUB>+H with the reaction step of H+O<SUB>2</SUB>→O+OH, an indicator of the overall reaction rate for the H atoms. This resulted in a weakened interacting flame. Such chemical reactions of the additional CO<SUB>2</SUB> were examined in detail to describe the flame characteristics.
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Expression Patterns of HIF-1α Under Hypoxia in Vascular Smooth Muscle Cells of Venous Malformations
Chung, Ho Yun,Lee, Seok Jong,Lee, Jong Min,Huh, Seung,Kim, Hyung Kee,Kwon, O Hyun,Lim, Hyun Ju,Oh, Eun Jung,Kim, Tae Jung,O, Teresa M.,Waner, Milton Wolters Kluwer Health, Inc. All rights reserved. 2015 Annals of plastic surgery Vol.75 No.3
PURPOSE: The molecular pathophysiology of venous malformations (VMs), which are a type of vascular malformation, is poorly understood. Until now, it is known that VM lesions are related to the process of angiogenesis. Because angiogenesis is induced under hypoxic conditions, hypoxia is thought to be important in VM lesion formation. Therefore, we examined the implications of hypoxia on the biological behavior of VM vascular smooth muscle cells (VSMCs). In doing so, we investigated the expression patterns of hypoxia-inducible factor-1α (HIF-1α), which plays a key role in hypoxia-induced angiogenesis, to provide a further understanding of the molecular mechanisms involved in VM. METHODS: Vascular smooth muscle cells from 5 normal veins and 5 VM lesions were cultured under moderate hypoxic conditions (3% O2, 5% CO2). The effects of hypoxia on HIF-1α expression were measured by immunocytochemical staining, reverse transcription-polymerase chain reaction, and real-time reverse transcription-polymerase chain reaction. RESULTS: Overall, the expression of HIF-1α in cells was high after exposure to hypoxia for 6 or 12 hours, but decreased after 24 hours of hypoxia. HIF-1α expression in VM VSMCs was 2 times higher than that in normal VSMCs. Immunocytochemically, HIF-1α was mainly located in the nucleus and the intensity in VM VSMCs was stronger after 6 and 12 hours of hypoxia when compared to the expression pattern of HIF-1α in VSMCs from normal tissue. This suggested that VM tissue is more susceptible to the effects of hypoxia than normal tissue. CONCLUSIONS: These results indicate that the high expression of HIF-1α in VM VSMCs under hypoxic conditions could be an important factor for stimulating downstream angiogenesis in VM. Furthermore, the results of this investigation could provide the basis for future studies of VM pathophysiology, and ultimately lead to the development of new therapeutic approaches.
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엔진윤활유 중 Ethylene Glycol의 용제추출후 bistrimethylsilyltrifluoroacetamide(BSTFA)를 이용한 GC/MS 분석에 관한 연구
이준배(Joon-Bae Lee),권오성(O-Seong Kwon),유재훈(Jae-Hoon You),손성건(Shungkun Shon),성태명(Tae-Myung Sung),팽기정(Ki-Jung Paeng) 한국트라이볼로지학회 2012 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.28 No.6
For proper functioning, general machines usually need lubricant oil as a cooling, cleaning, and sealing agent at points of mechanical contact. The quality of lubricant oil can deteriorate during operation owing to various causes such as high temperature, combustion products and extraneous impurities. In this study, a heavy load stopped during operation, and the oil was analyzed to check whether any impurities were added. Extraction using acetonitrile followed by reaction with BSTFA(bistrimethylsilyl trifluoroacetamide) showed that, trimethylsilylated ethylene glycol was present in the lubricant oil. To quantify the ethylene glycol in the oil, deuterium-substituted ethylene glycol, which acted as an internal standard, was added to the sample and then extracted with the solvent. Next, the extract was reacted with the derivatizing agent(BSTFA) and then analyzed with GC/MS. The detection limit of this method was found to be 0.5 ㎍/g and the recovery of oil containing 20,000 ㎍/g of ethylene glycol was measured to be 94.8%. A damaged O-ring and eroded cylinder liner were found during the overhaul, which implied the leakage of coolant containing ethylene glycol into the lubricating system. The erosion of the cylinder liner was assumed to be due to cavitation of the coolant in the cooling system.
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Hepatitis C Virus Infection and Hepatotoxicity During Antituberculosis Chemotherapy
Kwon, Yong Soo,Koh, Won-Jung,Suh, Gee Young,Chung, Man Pyo,Kim, Hojoong,Kwon, O. Jung American College of Chest Physicians 2007 Chest Vol.131 No.3
<P>BACKGROUND: The risk of drug-induced hepatotoxicity (DIH) during treatment for tuberculosis (TB) in patients who are seropositive for the hepatitis C virus (HCV) is not clear. We evaluated whether HCV-seropositive patients are at a higher risk of DIH than control subjects during treatment for TB with standard short-course regimens. METHODS: Fifty-four HCV-seropositive patients with newly diagnosed active TB who were treated with isoniazid, rifampin, ethambutol, and/or pyrazinamide were included in the study population. Ninety-seven HCV-seronegative patients were selected as control subjects. RESULTS: Forty HCV-seropositive patients (74%) and 82 control subjects (85%) received an initial treatment regimen that included pyrazinamide. Twenty-two HCV-seropositive patients (41%) and 19 control subjects (20%) exhibited elevated liver enzyme levels during TB treatment, including transient elevation of transaminase. DIH, defined as a liver transaminase level >/= 120 IU/L, occurred more frequently in HCV-seropositive patients (7 of 54 patients, 13%) than in control subjects (4 of 97 patients, 4%). Isoniazid and rifampin were reintroduced after the liver transaminase level returned to baseline in five HCV-seropositive patients exhibiting DIH, and all these retrials proved to be successful. CONCLUSIONS: These findings suggest that treatment for TB in HCV-seropositive patients could be pursued in the usual manner, using standard short-course regimens, with the condition that monthly liver function tests are carefully performed.</P>
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( Jung Hye Hwang ),( Yong Soo Kwon ),( Eun Hae Kang ),( Won Jung Koh ),( Kyeong Woo Kang ),( Ho Cheol Kim ),( Man Pyo Chung ),( Ho Joong Kim ),( O Jung Kwon ),( Gee Young Suh ) 대한내과학회 2004 The Korean Journal of Internal Medicine Vol.19 No.4
Background : Partial liquid ventilation (PLV) and prone positioning can improve the arterial oxygenation (PaO2) in acute lung injury (ALI). We evaluated the effect of prolonged prone positioning during partial liquid ventilation (PLV) in a canine model of
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Kwon, O-Pil,Kwon, Seong-Ji,Jazbinsek, Mojca,Brunner, Fabian D. J.,Seo, Jung-In,Hunziker, Christoph,Schneider, Arno,Yun, Hoseop,Lee, Yoon-Sup,Gü,nter, Peter WILEY-VCH Verlag 2008 Advanced functional materials Vol.18 No.20
<P>We investigate a configurationally locked polyene (CLP) crystal 2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile (OH1) containing a phenolic electron donor, which also acts as a hydrogen bond donor. The OH1 crystals with orthorhombic space group Pna2<SUB>1</SUB> (point group mm2) exhibit large second-order nonlinear optical figures of merit, high thermal stability and very favorable crystal growth characteristics. Higher solubility in methanol and a larger temperature difference between the melting temperature and the decomposition temperature of OH1 compared to analogous CLP crystals, are of advantage for solution and melt crystal growth, respectively. Acentric bulk OH1 crystals of large sizes with side lengths of up to 1 cm with excellent optical quality have been successfully grown from methanol solution. The microscopic and macroscopic nonlinearities of the OH1 crystals are investigated theoretically and experimentally. The OH1 crystals exhibit a large macroscopic nonlinearity with four times larger powder second harmonic generation efficiency than that of analogous CLP crystals containing dimethylamino electron donor. A very high potential of OH1 crystals for broadband THz wave emitters in the full frequency range of 0.1–3 THz by optical rectification of 160 fs pulses has been demonstrated.</P> <B>Graphic Abstract</B> <P>Configurationally locked polyene OH1 crystals containing a phenolic electron donor exhibit large second-order nonlinear optical figures of merit, high thermal stability, and very favorable crystal-growth characteristics. A very high potential of OH1 crystals for broadband THz wave emitters in the full frequency range of 0.1–3 THz by optical rectification of 160 fs pulses has been demonstrated. <img src='wiley_img/1616301X-2008-18-20-ADFM200800633-content.gif' alt='wiley_img/1616301X-2008-18-20-ADFM200800633-content'> </P>
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Jung, Jin Ah,Kim, Tae-Eun,Lee, Hyun,Jeong, Byeong-Ho,Park, Hye Yun,Jeon, Kyeongman,Kwon, O Jung,Ko, Jae-Wook,Choi, Rihwa,Woo, Hye-In,Koh, Won-Jung,Lee, Soo-Youn Dove Medical Press 2015 Drug design, development and therapy Vol.9 No.-
<P><B>Background/aim</B></P><P>Isoniazid (INH) is an essential component of first-line anti-tuberculosis (TB) treatment. However, treatment with INH is complicated by polymorphisms in the expression of the enzyme system primarily responsible for its elimination, N-acetyltransferase 2 (NAT2), and its associated hepatotoxicity. The objective of this study was to develop an individualized INH dosing regimen using a pharmacogenetic-driven model and to apply this regimen in a pilot study.</P><P><B>Methods</B></P><P>A total of 206 patients with TB who received anti-TB treatment were included in this prospective study. The 2-hour post-dose concentrations of INH were obtained, and their <I>NAT2</I> genotype was determined using polymerase chain reaction and sequencing. A multivariate regression analysis that included the variables of age, sex, body weight, and <I>NAT2</I> genotype was performed to determine the best model for estimating the INH dose that achieves a concentration of 3.0–6.0 mg/L. This dosing algorithm was then used for newly enrolled 53 patients.</P><P><B>Results</B></P><P>Serum concentrations of INH were significantly lower in the rapid-acetylators than in the slow-acetylators (2.55 mg/L vs 6.78 mg/L, median, <I>P</I><0.001). A multivariate stepwise linear regression analysis revealed that NAT2 and body weight independently affected INH concentrations: INH concentration (mg/L) =13.821–0.1× (body weight, kg) −2.273× (number of high activity alleles of <I>NAT2</I>; 0, 1, 2). In 53 newly enrolled patients, the frequency at which they were within the therapeutic range of 3.0–6.0 mg/L was higher in the model-based treatment group compared to the standard treatment group (80.8% vs 59.3%).</P><P><B>Conclusion</B></P><P>The use of individualized pharmacogenetic-guided INH dosage regimens that incorporate <I>NAT2</I> genotype and body weight may help to ensure achievement of therapeutic concentrations of INH in the TB patients.</P>
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PLD법을 이용한 TmBa₂Cu₃O<SUB>7-x</SUB> 초전도 선재 제작 및 전류전송특성 평가
권오정(O-Jong Kwon),고락길(Rock-Kil Ko),구현(Hyun Koo),배성환(Sung-Hwan Bae),정명진(Myung-Jin Jung),오상수(Sang-Soo Oh),박찬(Chan Park) 대한전기학회 2009 전기학회논문지 Vol.58 No.11
REBa₂Cu₃O7-d(REBCO) coated conductors(REBCO CCs) have been studied for electric power applications which require high current density wires. As long as the critical transition temperature(Tc) is concerned, REBCO CCs with large RE³? ions have been expected to have better current transport properties than those with smaller RE³? ions. For this reason, REBCO's with large RE³? ions which include GdBCO, NdBCO and SmBCO have been mainly considered as the superconducting layer of CCs. On the other hand, REBCO's with smaller RE³? ions are expected to have advantages in the fabrication process of CCs because of the lower melting temperature. But it has not yet been made clear which REBCO is the most suitable for the superconducting layer of CCs. In this study, we investigated the current transport properties of REBCO CCs with small RE³? ion and advantages of using that in the CC fabrication process. Thin films of TmBCO, which has smaller RE³? ion than most other RE³? ions, were fabricated on buffered metal substrate as the superconducting layer of CC by PLD process. TmBCO CC shows critical current density (Jc (77 K, sf) = 2.3 MA/㎠) high enough to be utilized for application in electric power devices. Compared with previous experiments using the same PLD system, deposition temperature was approximately 20 ℃ lower than NdBCO thin films on buffered metal substrates.
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Kwon, Man Jae,Yang, Jung-Seok,Lee, Seunghak,Lee, Giehyeon,Ham, Baknoon,Boyanov, Maxim I.,Kemner, Kenneth M.,O’Loughlin, Edward J. Elsevier 2015 Journal of hazardous materials Vol.296 No.-
<P><B>Abstract</B></P> <P>The effects of extreme geochemical conditions on microbial community composition were investigated for two distinct sets of sediment samples collected near weathered mine tailings. One set (SCH) showed extraordinary geochemical characteristics: As (6.7–11.5%), Pb (1.5–2.1%), Zn (0.1–0.2%), and pH (3.1–3.5). The other set (SCL) had As (0.3–1.2%), Pb (0.02–0.22%), and Zn (0.01–0.02%) at pH 2.5–3.1. The bacterial communities in SCL were clearly different from those in SCH, suggesting that extreme geochemical conditions affected microbial community distribution even on a small spatial scale. The clones identified in SCL were closely related to acidophilic bacteria in the taxa <I>Acidobacterium</I> (18%), <I>Acidomicrobineae</I> (14%), and <I>Leptospirillum</I> (10%). Most clones in SCH were closely related to <I>Methylobacterium</I> (79%) and <I>Ralstonia</I> (19%), both well-known metal-resistant bacteria. Although total As was extremely high, over 95% was in the form of scorodite (FeAsO<SUB>4</SUB>·2H<SUB>2</SUB>O). Acid-extractable As was only ∼118 and ∼14mgkg<SUP>−1</SUP> in SCH and SCL, respectively, below the level known to be toxic to bacteria. Meanwhile, acid-extractable Pb and Zn in SCH were above toxic concentrations. Because As was present in an oxidized, stable form, release of Pb and/or Zn (or a combination of toxic metals in the sediment) from the sediment likely accounts for the differences in microbial community structure. The results also suggest that care should be taken when investigating mine tailings, because large differences in chemical/biological properties can occur over small spatial scales.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Over 95% of solid-phase As was in the form of scorodite (FeAsO<SUB>4</SUB>·2H<SUB>2</SUB>O). </LI> <LI> <I>Methylobacterium</I>/<I>Ralstonia</I> were predominant in sediments with high levels of toxic metals. </LI> <LI> Extreme geochemical conditions affected microbial community distribution. </LI> <LI> Pb and/or Zn released from the sediment might cause the differences in microbial community. </LI> </UL> </P>
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