Effect of Long-Term Thermal Exposures on Microstructures and Mechanical Properties of Directionally Solidified CM247LC Alloy

H. W. Jeong,S. M. Seo,B. G. Choi,Y. S. Choi.,Y. K. Ahn,이재현 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.5

A directionally solidified CM247LC alloy was exposed at 871 °C and 982 °C for 1000 h, 5000 h, and 10000h under free stress in order to study the effect of microstructural degradation on the creep properties. None of the specimens exposed at temperatures up to 10000 h produced any kind of topologically close-packed phases because of the excellent phase stability of CM247LC alloy. The plate-like M6C carbide was formed only at exposure of 982 °C for 10000 h through a decomposition reaction between γ and MC. Moreover, an M23C6 carbide layer was observed between the M6C and the matrix. The exposure at 982°C for 5000 h and 10000 h had a spontaneous rafting of γ′ under free stress, while the exposure at 871 °C for 1000 h, 5000 h,and 10000 h had a non-rafted structure. The spontaneous rafted structure resulted in a drastic decrease in creep life. A 3-dimensional morphology of γ′ in the as-crept specimens, which were pre-exposed at 982 °C for 5000 h and 10000 h, had a non-rafted structure. This microstructural feature proves that the significant decrease in creep life of the specimen resulted from a loss of coherency between γ and γ′.

Transmissibility of novel H7N9 and H9N2 avian influenza viruses between chickens and ferrets

Ku, K.B.,Park, E.H.,Yum, J.,Kim, H.M.,Kang, Y.M.,Kim, J.C.,Kim, J.A.,Kim, H.S.,Seo, S.H. 3M Company 2014 Virology Vol.450 No.-

Previous studies have shown that the H7N9 avian influenza virus cannot be transmitted efficiently between ferrets via respiratory droplets. Here, we studied the infectivity of the H7N9 avian influenza virus in chickens and its transmissibility from infected to naive chickens and ferrets. The H7N9 virus (A/Anhui/½013) replicated poorly in chickens and could not be transmitted efficiently from infected chickens to naive chickens and ferrets. H7N9 virus was shed from chicken tracheae for only 2 days after infection and from chicken cloacae for only 1 day after infection, while the H9N2 avian influenza virus, which is endemic in chickens in many Asian countries, was shed from tracheae and cloacae for 8 days after infection. Taken together, our results suggest that chickens may be a poor agent of transmission for the H7N9 virus to other chickens and to mammals, including humans.

Hydrogen production by auto-thermal reforming of ethanol over nickel catalyst supported on metal oxide-stabilized zirconia

Youn, M.H.,Seo, J.G.,Song, I.K. Pergamon Press ; Elsevier Science Ltd 2010 International journal of hydrogen energy Vol.35 No.8

Metal oxide-stabilized mesoporous zirconia supports (M-ZrO<SUB>2</SUB> with different metal oxide stabilizer (M = Zr, Y, La, Ca, and Mg) were prepared by a templating sol-gel method. 20 wt% Ni catalysts supported on M-ZrO<SUB>2</SUB>(M = Zr, Y, La, Ca, and Mg) were then prepared by an incipient wetness impregnation method for use in hydrogen production by auto-thermal reforming of ethanol. The effect of metal oxide stabilizer (M = Zr, Y, La, Ca, and Mg) on the catalytic performance of supported nickel catalysts was investigated. Ni/M-ZrO<SUB>2</SUB>(M = Y, La, Ca, and Mg) catalysts exhibited a higher catalytic performance than Ni/Zr-ZrO<SUB>2</SUB> because surface oxygen vacancy of M-ZrO<SUB>2</SUB>(M = Y, La, Ca, and Mg) and reducibility of Ni/M-ZrO<SUB>2</SUB>(M = Y, La, Ca, and Mg) were enhanced by the addition of lower valent metal cation. Hydrogen yield over Ni/M-ZrO<SUB>2</SUB>(M = Zr, Y, La, Ca, and Mg) catalyst was monotonically increased with increasing both surface oxygen vacancy of M-ZrO<SUB>2</SUB>support and reducibility of Ni/M-ZrO<SUB>2</SUB>catalyst. Among the catalysts tested, Ni catalyst supported on yttria-stabilized mesoporous zirconia (Ni/Y-ZrO<SUB>2</SUB> showed the best catalytic performance.

CAN통신을 이용한 H-브릿지 멀티레벨 인버터의 PWM 동기화 및 위상전이 방법

박영민(Y.M.Park),유한승(H.S.Yoo),장성영(S.Y.Jang),이현원(H.W.Lee),이세현(S.H.Lee),서광덕(K.D.Seo) 전력전자학회 2004 전력전자학술대회 논문집 Vol.- No.-

H-브릿지 멀티레벨 인버터는 여러 개의 단상 Power Cell을 직렬로 연결함으로써 저전압 전력용 반도체를 사용하여 고전압을 얻을 수 있고, 정현파에 가까운 출력전압 파형을 얻을 수 있는 멀티레벨 인버터 토폴로지이다. 본 토폴로지는 출력전압 레벨에 비례하여 Power Cell의 수가 증가하므로, 주제어기의 연산능력에 대한 부담증가와 신호선의 많아지는 단점이 있다. 따라서 Power Cell제어를 직접적인 PWM 신호가 아닌 통신을 사용함으로써 이러한 단점을 극복할수 있으며, 신뢰성 측면이나 보수/유지 측면에서도 유리하다. 본 논문은 산업현장에서 신뢰성을 인정받아 많이 사용되고 있는 직렬통신 방식의 일종인 CAN통신 인터럽터를 이용한 H-브릿지 멀티레벨 인버터 Power Cell의 PWM 동기화 및 위상전이 방법에 관한 것이다. 제안된 방법의 주요 장점은 주제어기와 셀 제어기 사이에 직렬통신(CAN)을 사용함으로써 주제어기와 셀 제어기의 신호선의 단순화, 주제어기의 부담 감소, Power Cell의 모듈화, 셀 단위의 보호동작 용이, 확장성 향상 그리고 제어 신호 및 Power Cell의 신뢰성을 향상에 있다. 13레벨로 구성된 H-브릿지 멀티레벨 인버터 시험을 통해 제안된 방법의 타당성과 신뢰성을 입증하였다.

Effects of flow rate of hydrogen and substrate temperature on the characteristics of IZO thin films for OLEDs

K. H. Seo,K.M.Lee 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.6

This study examined the effects of the H2 flow rate and the substrate temperature on the structural, electrical, and opticalcharacteristics of the IZO thin films intended for use as anode materials in OLEDs (organic light emitting diodes). These IZOthin films were deposited by RF magnetron sputtering at room temperature and 300 oC at various H2 flow rates. To examinethe effects of H2, the H2 flow rate in the argon mixing gas was changed from 0.1 sccm to 0.9 sccm. IZO thin films depositedat room temperature showed an amorphous structure, whereas IZO thin films deposited at 300 oC showed a crystallinestructure with an (222) preferential orientation regardless of the H2 flow rate. The electrical resistivity of the IZO thin filmsdecreased with increasing H2 flow rate under Ar+H2. The change in the electrical resistivity with increasing H2 flow rate wasinterpreted mainly in terms of the charge carrier concentration rather than the charge carrier mobility. The electricalresistivity of the amorphous-IZO films deposited at R.T. was lower than that of the crystalline-IZO thin films deposited at300 oC. All the films showed an average transmittance of more than 83% in the visible range. The optical band gap of the IZOfilms increased with increasing H2 flow rate. The current density and luminance of the OLED devices with IZO thin filmsdeposited at room temperature in 0.9 sccm H2 ambient gas were the highest among the films examined. These properties wereattributed to the improved optical band gap, which plays a major role in the OLED device performance.

Oxidative degradation of endotoxin by advanced oxidation process (O₃/H₂O₂ & UV/H₂O₂)

Oh, B.T.,Seo, Y.S.,Sudhakar, D.,Choe, J.H.,Lee, S.M.,Park, Y.J.,Cho, M. Elsevier Scientific Pub. Co 2014 Journal of hazardous materials Vol.279 No.-

The presence of endotoxin in water environments may pose a serious public health hazard. We investigated the effectiveness of advanced oxidative processes (AOP: O<SUB>3</SUB>/H<SUB>2</SUB>O<SUB>2</SUB> and UV/H<SUB>2</SUB>O<SUB>2</SUB>) in the oxidative degradation of endotoxin. In addition, we measured the release of endotoxin from Escherichia coli following typical disinfection methods, such as chlorine, ozone alone and UV, and compared it with the use of AOPs. Finally, we tested the AOP-treated samples in their ability to induce tumor necrosis factor alpha (TNF-α) in mouse peritoneal macrophages. The production of hydroxyl radical in AOPs showed superior ability to degrade endotoxin in buffered solution, as well as water samples from Korean water treatment facilities, with the ozone/H<SUB>2</SUB>O<SUB>2</SUB> being more efficient compared to UV/H<SUB>2</SUB>O<SUB>2</SUB>. In addition, the AOPs proved effective not only in eliminating E. coli in the samples, but also in endotoxin degradation, while the standard disinfection methods lead to the release of endotoxin following the bacteria destruction. Furthermore, in the experiments with macrophages, the AOPs-deactivated endotoxin lead to the smallest induction of TNF-α, which shows the loss of inflammation activity, compared to ozone treatment alone. In conclusion, these results suggest that AOPs offer an effective and mild method for endotoxin degradation in the water systems.

절식과 출하취급이 출하돈의 스트레스 관련 혈액성상과 도체품질에 미치는 영향

김두환,하덕민,서종태,Kim, D.H.,Ha, D.M.,Seo, J.T. 한국축산환경학회 2007 축산시설환경학회지 Vol.13 No.2

출하전 절식과 출하 취급이 출하돈의 혈액성상과 도체품질에 미치는 영향을 분석하기 위하여 출하전 12시간, 24시간 절식한 그룹 및 절식하지 않는 그룹으로 구분하고 각각의 그룹에 대하여 출하 취급을 최대한 부드럽게 혹은 상차, 하차, 계류 과정에 전기봉 사용을 포함하여 고의적으로 거칠게 하는 그룹으로 나누어 체중 약 110kg에 출하되는 삼원교잡종 비육돈 144두를 공시하여 조사, 분석하였다. 모든 출하돈은 계류장 도착 후 3시간 동안 계류하였다. 혈액은 도축직후에 채취하였고 배최장근 시료는 도축 12시간 후(overnight)에 채취하여 분석에 사용하였다. 혈중 glucose 농도는 절식하지 않은 그룹에 비하여 12시간 및 24시간 절식 그룹이 낮았으나 cortisol 농도는 반대로 절식하지 않은 그룹에 비하여 24시간 절식 그룹이 높게(p<0.05) 나타났다. 스트레스와 관련된 glucose, cortisol, creatine kinase 및 lactate dehydrogenase 농도는 출하 취급을 부드럽게 한 그룹에 비하여 고의적으로 거칠게 취급한 그룹에서 높았다. 그러나 스트레스 관련 혈액성상에 대한 절식시간과 취급 스트레스간의 상호작용 효과는 인정되지 않았다. PSE 발생율과 drip loss는 절식하지 않은 그룹보다 12시간, 24시간 절식 그룹이 낮았으나 도체 pH와 육색은 절식 시간의 영향은 나타나지 않았다. 그러나 PSE 발생율과 도체의 이화학적 특성은 출하 스트레스에 의한 차이가 인정되지 않았다. 결론적으로 출하전 12시간(하루밤) 절식은 PSE 발생을 줄이기 위한 좋은 방법이 될 수 있다. 또한 충분한 계류는 출하시 거친 취급으로 인한 도체품질에 미치는 영향을 줄일 수 있을 것으로 보인다. 그러나 출하 취급이 거칠면 혈중 스트레스 관련 지표들의 농도가 증가하여 동물복지를 나쁘게 할 수 있어 거친 취급은 피해야 할 것으로 판단된다. One hundred and forty-four cross-bred market pigs weighing approximately 110 kg were randomly divided into six groups in a 3 (duration of fasting prior to loading; 0, 12 and 24 h) ${\times}$ 2 (handling stress; minimal vs stimulated handling stress) factorial arrangement of treatments. The stimulated handling stress group received overally rough handling including electric prod stimulation during loading, transport and lairage at least once at each step. All the animals received 3-h lairage prior to slaughter. Blood and longissimus dorsi muscle (LM) samples were taken at slaughter and after overnight chilling of the carcass, respectively. Mean plasma glucose concentration, as expected, was less in the 12 h- or 24 h-fasting group than in the 0 h-fasting, whereas cortisol concentration was greater (P<0.05) in the 24 h- vs 0 h-fasting group. Plasma concentrations of stress indicators glucose, cortisol, creatine kinase and lactate dehydrogenase were greater in the stimulated vs minimal handling stress group. There were no interactions between the duration of fasting and handling stress in their effects on these blood variables. The incidence of pale, soft and exudative (PSE) carcass and drip loss of LM were reduced in the 12 h- or 24 h- vs 0 h-fasting group, whereas the 24-h postmortem LM pH and color including the lightness and redness were not affected by the duration of fasting. The incidence of PSE carcass and physicochemical characteristics of LM, however, were not changed by the stimulated vs minimal handling stress. In conclusion, results suggest that fasting the market pig overnight prior to transport is desirable in terms of reducing the incidence of PSE carcass. Rough handling of market pigs may not affect the carcass quality of the animals when an enough lairage time is provided. However, rough handling inflicts a stimulated stress on the animal, which is manifested by increased blood concentrations of stress indicators, and therefore should be avoided fer animal welfare.

Effect of purification conditions on gas storage and separations in a chromium-based metal-organic framework MIL-101

Lee, S.J.,Yoon, J.W.,Seo, Y.K.,Kim, M.B.,Lee, S.K.,Lee, U.H.,Hwang, Y.K.,Bae, Y.S.,Chang, J.S. Elsevier 2014 Microporous and mesoporous materials Vol.193 No.-

The effect of purification condition of a chromium terephthalate MIL-101 on gas storage (H<SUB>2</SUB>, CO<SUB>2</SUB>, and C<SUB>2</SUB>H<SUB>2</SUB>) and C2 hydrocarbon separations was investigated for MIL-101a, MIL-101b, and MIL-101c, which were obtained by three-step sequential purification using hot water/ethanol and aqueous NH<SUB>4</SUB>F solution treatments. MIL-101c was the best in terms of gas storage capacities among the three samples possibly due to the removal of free and coordinated terephthalic acids. Remarkably, MIL-101c exhibits among the highest total hydrogen uptake at 50bar and 77K (9.9 wt%) and shows considerably large deliverable capacity between 1.5 and 50bar (7.6 wt%). Moreover, MIL-101c shows among the highest C<SUB>2</SUB>H<SUB>2</SUB> storage capacity (6.4mmolg<SUP>-1</SUP>) and deliverable capacity (4.3mmolg<SUP>-1</SUP>) at 1bar and 313K. For C<SUB>2</SUB>H<SUB>2</SUB>/C<SUB>2</SUB>H<SUB>6</SUB>, C<SUB>2</SUB>H<SUB>2</SUB>/C<SUB>2</SUB>H<SUB>4</SUB>, and C<SUB>2</SUB>H<SUB>4</SUB>/C<SUB>2</SUB>H<SUB>6</SUB> separations, MIL-101c exhibits higher adsorption capacities, working capacities and adsorption figure of merit (AFM) values while MIL-101b shows higher selectivities and sorbent selection parameters. These results clearly show that a proper purification of MIL-101 is important for gas storage and gas separations.

Long-range transport of giant particles in Asian dust identified by physical, mineralogical, and meteorological analysis

Jeong, G. Y.,Kim, J. Y.,Seo, J.,Kim, G. M.,Jin, H. C.,Chun, Y. Copernicus GmbH 2014 Atmospheric chemistry and physics Vol.14 No.1

<P>Abstract. Giant particles transported over long distances are generally of limited concern in atmospheric studies due to their low number concentrations in mineral dust and possible local origin. However, they can play an important role in regional circulation of earth materials due to their enormous volume concentration. Asian dust laden with giant particles was observed in Korea on 31 March 2012, after a migration of about 2000 km across the Yellow Sea from the Gobi Desert. Scanning electron microscopy (SEM) revealed that 20% of the particles exceeded 10 μm in equivalent sphere diameter, with a maximum of 60 μm. The median diameter from the number distribution was 5.7 μm, which was larger than the diameters recorded of 2.5 and 2.9 μm in Asian dust storms in 2010 and 2011, respectively, and was consistent with independent optical particle counter data. Giant particles (>10 μm) contributed about 89% of the volume of the dust in the 2012 storm. Illite-smectite series clay minerals were the major mineral group followed by quartz, plagioclase, K-feldspar, and calcite. The total phyllosilicate content was ~52%. The direct long-range transport of giant particles was confirmed by calcite nanofibers closely associated with clays in a submicron scale identified by high-resolution SEM and transmission electron microscopy. Since giant particles consisted of clay agglomerates and clay-coated quartz, feldspars, and micas, the mineral composition varied little throughout the fine (<5 μm), coarse (5-10 μm), giant-S (10-20 μm), and giant-L (>20 μm) size bins. Analysis of the synoptic conditions of the 2012 dust event and its migration indicated that the mid-tropospheric strong wind belt directly stretching to Korea induced rapid transport of the dust, delivering giant particles. Giant dust particles with high settling velocity would be the major input into the terrestrial and marine sedimentary and ecological systems of East Asia and the western Pacific. Analysis of ancient aeolian deposits in Korea suggested the common deposition of giant particles from Asian dust through the late Quaternary Period. The roles of giant particles should be reviewed with regard to regional circulation of mineral particles and nutrients. </P>

초기성인의 생활습관과 당뇨에 대한 지식

소선이,마지은,고지윤,김은혜,박현화,서유진,서형은,유은미,이하늬,이혜인,정지연,현혜리,이자형,정덕유,강지숙 이화여자대학교 간호과학대학 2009 이화간호학회지 Vol.- No.43

Purposes :The purposes of this study was to investigate the self-managing status according to the life styles and the diabetic knowledge of early adulthood. The subjects in this study were 240people, the early adult aged twenties to thirties living in the metropolitan area. Data were collected by using self-administered questionnaires that measure about the knowledge of diabetes; the dietetic behavior; the knowledge of diet; the exercise behavior; the knowledge of exercise. Descriptive statistics, t-test, ANOVA, and correlation were used for data analysis. Result :1. At the knowledge of diabetes degree based on the general character, the subjects who had experiences of diabetic education have higher degree of the diabetic knowledge. 2. At the knowledge of diabetes degree according to the life style, the subjects who have regular diet are appeared highly. Also the subjects who don't take much food of animal origin have higher degree. 3. At the knowledge of diet based on the life style, the subjects who don't keep three times meals a day are appeared highly. Also the subjects who have regular diet have higher degree. 4. At the knowledge of exercise according to the life style, the subjects who take extra nutritions 3-4 times a week are appeared highly. Although the subjects tend to know about dietary, exercise and health management, it showed that they actually don't perform what they know in their everyday of life. The reason for this could be the lack of perceived seriousness about diabetes mellitus. Thus as nursing professionals, we should provide them proper health education and support. Moreover, advanced research on the empowerment is warranted.