공기 싸이클론 분리 장치의 분체 분리 효율

姜錫浩,朴永孝,金珠浩,朱星浩 嶺南大學校 工業技術硏究所 1985 연구보고 Vol.13 No.1

The collection efficiency of the Lapple's standard-type cyclone separator was determined in order to investigate the effects of the particle size of the dust samples, the dust loading, and the air inlet velocity to the cyclone under the ambient conditions. The experimental conditions are in the following ranges; the air inlet velocity; 5 to 14.7 m/s, the particle sizes of the mono-dispersed system; 14 to 280 ㎛, the dust loading; 17.8 to 58.6 g/㎥, respectively. The collection efficiencies determined were compared with those predicted by the semi-empirical equations proposed earlier by Strauss (³) and by Licht et al, (⁴) and those are shown to be increased, as the particle size of the sample dusts and the air inlet velocity increase, respectively. However, the effect of the dust loading in the air could not be recognized, but slightly increased. For the poly-dispersed particulate samples, having a wide particle size distribution, the grade or separation efficiency curve was experimentally determined to specify more exactly the cyclone separation performance, and the result was discussed with the statistical analysis previously worked by Herrmann.(??)

Curcumin protects retinal pigment epithelial cells against oxidative stress via induction of heme oxygenase-1 expression and reduction of reactive oxygen

Woo, Je Moon,Shin, Da-Yong,Lee, Sung Ju,Joe, Yeonsoo,Zheng, Min,Yim, Jin Ho,Callaway, Zak,Chung, Hun Taeg Molecular Vision 2012 Molecular vision Vol.18 No.-

<P><B>Purpose</B></P><P>To determine whether curcumin induces expression of the defensive enzyme heme oxygenase-1 (HO-1) and protects cells against oxidative stress in cultured human retinal pigment epithelial cells.</P><P><B>Methods</B></P><P>Effective concentrations and toxicities of curcumin were determined after 3 h of curcumin treatment with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Confluent human retinal pigment epithelium cell lines (ARPE-19) were preincubated with curcumin and oxidatively challenged with H<SUB>2</SUB>O<SUB>2</SUB>. HO-1 expression was determined with western blot analysis. To confirm the protective role of HO-1 in oxidative stress, small interfering RNA (siRNA) against HO-1 or inhibitor of HO-1 was treated with curcumin in retinal pigment epithelium cells. Intracellular levels of reactive oxygen species (ROS) were measured with flow cytometry and confocal microscopy. Apoptosis was evaluated with Annexin V-fluoroscein isothiocyanate staining.</P><P><B>Results</B></P><P>Curcumin had little cytotoxicity at concentrations less than 30 μM, and HO-1 expression was the highest at the 15 μM concentration. At this concentration, curcumin also increased the cytoprotective effect against the oxidative stress of H<SUB>2</SUB>O<SUB>2</SUB> through the reduction of ROS levels in human retinal pigment epithelial cells. Curcumin’s effect on the reduction of ROS was mediated by the increase in HO-1 expression.</P><P><B>Conclusions</B></P><P>Curcumin upregulated the oxidative stress defense enzyme HO-1 and may protect human retinal pigment epithelial cells against oxidative stress by reducing ROS levels.</P>

Adenovirus-mediated heme oxygenase-1 gene transfer to neonatal porcine islet-like cluster cells: the effects on gene expression and protection from cell stress

염혜정,Han Ro,Sol Ji Park,Ju Ho Hong,Bumrae Cho,김화정,Sung Joo Kim,황종익,이병천,안규리,양재석 한국바이오칩학회 2012 BioChip Journal Vol.6 No.1

Porcine islet xenotransplantation is a promising strategy for the treatment of diabetes that overcomes donor shortages. However, islet xenografts are susceptible to oxidative stress and apoptosis. Heme oxygenase-1 (HO-1) has been shown to protect cells from oxidative stress, apoptosis and inflammation. Here, we investigated whether introduction of human HO-1 (hHO-1) into neonatal porcine islet-like cell clusters (NPCCs) can induce beneficial transcriptional changes in NPCCs against cellular stress. NPCCs were transduced with either adenovirus-HO-1 (Ad-HO-1) or control adenovirus-GFP (Ad-GFP). After treatment with hydrogen peroxide (H2O2) for 24 hours, nitrite oxide (NO) production assays were performed to detect oxidative stress. Microarray analysis was performed using a pig oligonucleotide 44 K gene chip. We profiled transcriptional changes to apoptosis, oxidant and inflammatory genes, and real-time PCR analysis was also performed to confirm the microarray results. Survival of NPCCs after treatment with H2O2 was significantly higher in the Ad-HO-1 group (p⁄0.001), and NO production also decreased in the Ad-HO-1 group (p⁄0.01). The microarray results showed that the expression of pro-apoptosis genes such as CASP3, CASP7, CASP10, CIDE-B and CIDE-C was significantly decreased in the Ad-HO-1 virus group (CASP10; p⁄0.05, CASP3, CIDE-C; p⁄0.01, CASP7, CIDE-B; p⁄0.001). We also found that the expression of oxidative stresses genes including COX1, COX2, CYB5A, SDHD and NOS2 was decreased, and that the anti-oxidant genes Gpx1 and SOD2 were increased in the Ad-HO-1 group (NOS2; p⁄0.05, COXI, COX2, CYB5A, SDHD, SOD2, GPX1; p⁄0.001). However, inflammatory gene expression was not significantly changed. Realtime PCR analysis confirmed the results of the microarray analysis. These results shed light on the underlying mechanisms of the protective effects of hHO-1 on porcine islets from cellular stresses and suggest that hHO-1 could be a promising target gene for the production of transgenic pigs that confer improved islet xenograft survival.

타타늄의 열처리 조건에 따른 동전위 양극분극특성 및 표면 미세구조 변화

주동현,이용렬,정영화,양홍서,박상원,이도재,송호준,박영준 大韓齒科器材學會 2002 대한치과재료학회지 Vol.29 No.2

The corrosion resistance of metallic implants is essential for successful implant osseointegration. Moreover, the implant surface should have appropriate surface roughness for the attachment of the osteoblast and collagen fibrils. When titanium is exposed to air a thermodynamically very stable oxide film is formed at once. This oxide is very thin and yet it protects the metal from corrosion instantaneously. However, the oxide would not be ideal, and it would be supposed that the state of oxide film would be various by the different conditions when it is formed. The objective of this study was to evaluate the electrochemical properties and surface microstructural changes of titanium after passivation treatment or exposure to high heat (in vacuum or in air). ASTM grade 2 commercially pure titanium (Ti) disks of 10㎜ diameter were wet ground and polished with 240 and 600 grit SiC, and then ultrasonically cleaned with distilled water and ethanol. Cleansed as-received samples (As-R group) were passivated with 30% nitric acid solution at 50℃ for 15 minutes to make the Pas group. The Std-V samples were made by treating the Ti disks in vacuum quartz tube (10^-8 Torr) at 530℃ for 40 min for stress relieving, followed by annealing at 700℃ for 90 min, and then slow cooling to room temperature. The Std-A samples undergo identical procedure as the Std-V group except that it is done in air. For 530℃-V samples, Ti disks were heated at 530℃ for 40 minutes and slow cooled to room temperature. The 1000℃-V samples were produced by heating Std-V specimens again at 1000℃ for 2 hr, followed by cooling to room temperature. 530℃-A and 1000℃-A samples were also prepared. Potentiodynamic anodic polarization measurement, SEM, AFM and XRD analysis were performed to evaluate the effects of the various treatments. The difference in the mean values of E_corr between groups showed statistically significant difference (P<0.05), but that of I_corr did not show significance (P>0.05). When Ti surface was passivated there was a shift of corrosion potential (E_corr) in the noble direction and a lower corrosion current density (I_corr) value. Std-A samples showed most noble E_corr value among the tested groups. 530℃-V samples showed more noble E-corr than other tested groups except Std-A group. 1000℃-V samples showed more noble E-corr than those of Std-V sample. In the case of Std-, 530℃- and 1000℃-groups, -A sub-groups showed better corrosion resistant characteristics than -V sub-groups in regard to E-corr and I_corr values. In the SEM observations, the surfaces of the As-R samples showed only scratch line on smooth surface. In Pas samples, thick oxide layer covered the surface under high magnification observation. 530℃-A samples were covered by oxide granules, and Std-A samples had 25~50 nm-thick acicular oxides. The 1000℃-A samples were covered by coarse oxide crystals with a granule diameter of 0.1~0.6 μm having a gross appearance of milky white color, which was identified by XRD as a rutile. On the other hand, 1000℃-V samples showed an Widmansta¨tten structrue of which the orientation of the lattice is formed along crystallographic planes of the parent crystals. On the AFM observation, 530℃-A samples showed RMS roughness of 79.38 nm which is 5 times rougher than those of the As-R samples. Std-A sample had a roughness of 330.47 nm which is about 20-times rougher than that of the As-R sample. 1000℃-A samples were covered by coarse granular oxides and the roughness were about 0.56 μm. Vacuum sub-group samples showed a more smooth surface than air sub-group samples, and the oxide film was more dense. Due to variability of the surface treatment and heat treatment conditions, the process of the oxide formation seems to be affected thereby making the corrosion properties and surface micro-morphology different. However, more various electrochemical analysis together with surface analysis, and an investigation for the effects of those on the osteoblast cell adhesion and calcium phosphate apposition are needed for the improvement of the osseointegration rates of the titanium implants.

지오그리드 보강토 옹벽에 관한 유한요소해석

주재우,연명옥,한상호,박병곤 순천대학교 2000 순천대학교 자연과학논문집 Vol.19 No.1

It is difficult to analyze the behavior of the geogrid reinforced soil walls, because most of the design methods for the reinforced soil structures with geogrids are based on the theory of the rigid-plasticity which takes no account of displacement and deformation of reinforcing material in the soil. In this study, the finite element analyses of geogrid reinforced retaining walls are performed to suggest an useful design method which consider the displacement and deformation of reinforcing material in the soil. The reinforcing effects on geogrid reinforced retaining wall are related with the length and interval of reinforcing materials. So the effects are analyzed with four different interval of reinforcing materials. It can be concluded from the results of analyses that the wall displacement, the earth pressure on the wall, the vertical stress distribution in the foundation and the settlement of backfill surface are decreased in direct proportion to the decrease of the interval.

Bi₂Sr₂Ca₂Cu₃Oy 다결정의 전기적 활성화 에너지에 관한 연구

주유환,이상찬,손인호 경남대학교 신소재연구소 2003 신소재연구 Vol.15 No.2

Bi-(2)Sr_(2)Ca-(2)Cu_(3)O_(y) 다결정의 비저항을 전류와 온도의 함수로 측정하여 활성화에너지를 구하였다. 인가 전류가 증가함에 따라 임계전이 온도는 감소하였고 임계전이 온도폭은 증가하였으며, 활성화 에너지는 감소하였다. 인가 전류에 대한 활성화 에너지의 감소율은 약 -0.2로 나타났다. 개개의 볼텍스의 운동은 자기 비저항 실험의 결가와 같은 것으로 보인다. Measuring the temperature dependence of resitivity of Bi₂Sr₂Ca₂Cu₃O_(y), poly crystal we have obtained the activation energy. It is found that the critical transition temperature and the activation energy decrease and the width of critical transition temperature increases with increase of the applied current. The decreasing rate of activation energy is -0.2. The individual vortex creep seems to be the same as that in the result of the magnetic resitivity experiment.

Telomere의 기능 손실에 의한 Telomerase 결핍 세포의 성장 억제에 대한 연구

주연진,박정은,전경미,김창민,김상훈,박원봉,이기호 대한암예방학회 2002 Journal of cancer prevention Vol.7 No.3

외상 후 발생한 무지의 Boutonniere 변형

주홍실,권호,정성노 大韓成形外科學會 2004 Archives of Plastic Surgery Vol.31 No.3

데이터 웨어하우징의 구축과 발전동향

주상호,이종호 公州大學校工科大學生産技術硏究所 1998 論文集 Vol.6 No.-

Data Warehousing is a data set of subject-orientation, integration, time variancy, nonvolatility to support decision making. Nowadays, information technology is changing past OLTP environment into OLAP environment. And DW is most suitable environment support decision-making for competitive advantages in management activities. So, to have a higher competitiveness advantages, in case of building DW, it is very important to look for the proper system building technique after the integrated review and analysis considering the purpose and the amount of data, etc.

운동선수의 여가활동에 관한 연구

김주성,강정호 慶星大學校 1999 論文集 Vol.20 No.2

The purpose of this study was to analyze the leisure activities participant of sportsmen and to give information on leading the sportsmen. The sample was draw from 247 male and female (athlete, summer, handball player and taekwondo player) in sports activated who from the high school in K and P metropolitan city. The data were collected from a self - administrated questionnaires and the data were computerized by use of SPSS/PC+ program. The results obtained through the analysis of these data can be largely summarized as nine points as follows ; firstly, For the question about the definition of leisure activities, answered to 'rest' item (36.0%). secondly, For the question about the necessity of leisure activities, answered to 'dissatisfaction' item (65.99%). thirdly, For the question about the purpose of leisure activities, answered to 'solution of stress' item(37.25%). fourthly, For the question about the satisfied of leisure activities, answered to 'ordinariness' item(41.30%). fifthly, For the question about the leisure activity a place, answered to 'game room' item (20.24%). sixthly, For the question about the information collection of leisure activities, answered to 'friend' item (42.11%). seventhly, For the question about the partner of leisure activities, answered to 'a friend of the same sex' item (34.82%). eighthly, For the question about the reasons for not participation in leisure activities, answered to 'fatigue' item (33.20%). ninthly, For the question about the expense of leisure activities, answered to 'social expenses' item (37.25%).