백서 뇌의 Ciliary Neurotrophic Factor 발현에 관한 면역조직화학적 연구

천현미,이영호,김원식 충남대학교 의과대학 지역사회의학연구소 1997 충남의대잡지 Vol.24 No.1

It was reported recently that ciliary neurotrophic factor (CNTF) is mainly present in the Schwann cells and asrocytes and maintain the motor neurons in postnatal periods. But there is no detailed research about the localization of CNTF. Several articles showed that there were many regions which have CNTF positive neurons. To test the unsettled CNTF immunoreactivity, the immunohistochemistry with CNTF antibody (Research & Development of the BML, Japan) was performed in th erat brain. The adult female rats weighing aound 200g were fixed by perfusion and 40-㎛-thick frozen sections were taken, and perform CNTF immunohistochemistry. The CNTF immunoreactivity was observed in the astrocytes of the optic nerve, olfactory nerve, fimbriae of the hippocampus, internal capsule, and cingulum, and in the non-astrocytes of the pyramidal tracts, the ventral portion of the pontine nucleus, and the central portion of the medulla oblongata. These data show that CNTF immunoreactivities present mainly in the astrocytes between the nerve fiber bundles in the cerebrum and in the non-astrocytes of the brain stem.

3차원 CFD 모형을 이용한 원형 교각의 국부세굴 특성 해석

오현식·김경호·양승룡 충북대학교 건설기술연구소 2008 충북대학교 건설기술연구소 논문집 Vol.27 No.1

Scour is a natural phenomenon, which occurs whenever a solid object is placed on loose sedimentary material, such as sand, in moving water. The flow of water is close to any such obstruction causes local increases in water velocity together with eddies and vortices. The flow phenomena are complex due to the presence of a boundary layer as well as and adverse pressure gradient set up by the bridge pier. Many researchers have conducted a vast number of experiments in laboratory flumes to investigate the local scour depth around a bridge pier. A few empirical formulas predicting the maximum scout depth have been developed under various experimental conditions. However, most of the experiments have been carried out in flumes under idealized conditions. such as steady flow, uniform sediment, simplified geometry, etc. The purpose of the study is to simulate accurately the flow field and scouring processes using a three-dimensional numerical flow model. In this study, for analyzing the mechanism of scouring process, CFD(computational fluid dynamics) model is used, based on the VOF(Volume of fluid) theory and finite differential equation. For the flow model, the simulated three-dimensional flatbed flow field(without bed slop) is compared with experimental data obtained by established scour equation and data. The results showed that 3D scouring flow field simulated by CFD model have almost the same phasis as experimental results.

파에 의한 해저 파이프라인의 국부세굴

오현식,김경호 충북대학교 산업과학기술연구소 2002 산업과학기술연구 논문집 Vol.16 No.1

Submarine pipelines, one of the most important subjects in coastal engineering, are widely used in coastal structures. The stability of submarine pipelines is more important than other offshore structures, because local scour have influence on exposed pipelines due to waves generated in shallow water region. The local scour influence by wave should be previously considered because the self-burial caused to local scour induces additional static or dynamic loads and various risk elements. However, local scour occurring in waves has not been investigated as widely as in currents. This paper presents experimental investigations of scour depth with respect to scour parameters using regular waves. The investigations encompass shallow water region conditions. Developments of scour near the pipeline are observed and recorded due to variations of wave periods, wave heights and pipe diameters. This paper analyzes correlation between KC number and various scour parameters. By investigating new approach method suggested by C¸evik et al.(1999), it is found that modified Ursell number is valid for main parameters occurring to local scour below pipeline. Also this study analyzes relation between KC number and modified Ursell number and suggests modified equation based on experimental data. Under special experimental conditions, incomplete scours are appeared. This is caused by multiple correlation made with water depth(d), wave heights(H), period(T) and pipe diameter(D).

건축 단열재의 장기 경년변화에 따른 열전도율 변화에 관한 실험 연구 Ⅱ

최현중,정영선,김경우,강재식,이승언 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1

The objective of this study is to test for thermal conductivity of architecture insulation materials in domestic buildings with environmental condition change. In study, we measured change of thermal conductivity with test temperature change, long-time leaving and change of contained water rate. For long-time leaving test, the specimens of building insulation materials were kept in test conditions, which were influenced by the outside environment. The results of the study show 1) the contained water rate of artificial mineral fiber insulations was big for others, 2) thermal conductivity rose as test temperature(median) grew up and 3) the extruding insulations and hardened Urethane foam changed thermal conductivity with environmental condition and time elapse.

Microwave-Assisted Synthesis of Graphene–SnO₂ Nanocomposites and Their Applications in Gas Sensors

Kim, Hyoun Woo,Na, Han Gil,Kwon, Yong Jung,Kang, Sung Yong,Choi, Myung Sik,Bang, Jae Hoon,Wu, Ping,Kim, Sang Sub American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.37

<P>We obtained extremely high and selective sensitivity to NO2 gas by fabricating graphene-SnO2 nanocomposites using a commercial microwave oven. Structural characterization revealed that the products corresponded to agglomerated structures of graphene and SnO2 particles, with small secondary SnOx (x <= 2) nanoparticles deposited on the surfaces. The overall oxygen atomic ratio was decreased with the appearance of an SnOx (x < 2) phase. By the microwave treatment of graphene SnO2 nanocomposites, with the graphene promoting efficient transport of the microwave energy, evaporation and redeposition of SnOx nanoparticles were facilitated. The graphene SnO2 nanocomposites exhibited a high sensor response of 24.7 for 1 ppm of NO2 gas, at an optimized temperature of 150 degrees C. The graphene SnO2 nanocomposites were selectively sensitive to NO2 gas, in comparison with SO2, NH3, and ethanol gases. We suggest that the generation of SnOx nanoparticles and the SnOx phase in the matrix results in the formation of SnO2/SnO2 homojunctions, SnO2/SnOx (x < 2) heterojunctions, and SnO2/graphene heterojunctions, which are responsible for the excellent sensitivity of the graphene SnO2 nanocomposites to NO2 gas. In addition, the generation of surface Sn interstitial defects is also partly responsible for the excellent NO2 sensing performance observed in this study.</P>

Target Detection probability simulation in the homogeneous ground clutter environment

Kim, In-Kyu,Moon, Sang-Man,Kim, Hyoun-Kyoung,Lee, Sang-Jong,Kim, Tae-Sik,Lee, Hae-Chang The Korean Society for Aeronautical and Space Scie 2005 International Journal of Aeronautical and Space Sc Vol.6 No.1

This paper describes target detection performance of millimeter wave radar that exits on non-stationary target detection schemes in the ground clutter conditions. The comparison of various CFAR process schemes such as CA(Cell-Average)-CFAR, GO(Greatest Of)/SO(Smallest Of)-CFAR, and OS(Order Statistics)-CFAR performance are applied. Using matlab software, we show the performance and loss between target detection probability and signal to noise ratio. This paper concludes the OS-CFAR process performance is better than any others and satisfies the optimal detection probability without loss of detection in the homogeneous clutter, When range bins increase.

Temperature Effect on ZnO/Si Thin Film Grown Using Metal Organic Chemical Vapor Deposition

Kim, Kwang-Sik,Lee, Jung-Ho,Kim, Hyoun Woo 대한금속재료학회 2002 METALS AND MATERIALS International Vol.8 No.6

We investigated the effect of deposition temperature on the growth and structural quality of ZnO films on Si(100) substrate using the metal organic chemical vapor deposition (MOCVD) technique. We revealed that highly c-axis oriented ZnO thin films were obtained at the temperature of 400 ℃. The film crystallinity improved and the surface smoothness decreased with increasing growth temperature.

Synthesis of zinc oxide semiconductors-graphene nanocomposites by microwave irradiation for application to gas sensors

Kim, Hyoun Woo,Kwon, Yong Jung,Mirzaei, Ali,Kang, Sung Yong,Choi, Myung Sik,Bang, Jae Hoon,Kim, Sang Sub Elsevier Sequoia 2017 Sensors and actuators. B Chemical Vol.249 No.-

<P><B>Abstract</B></P> <P>Microwave (MW) irradiation has obtained extensive importance in the field of synthesis and treatment of nanoparticles, because of its faster, cleaner and cost effectiveness than the other conventional and wet chemical methods. In this study, ZnO/graphene nanocomposites were prepared and subsequently post-treated by MW irradiation. Responses of the MW irradiated ZnO/graphene nanocomposites sensors were tested towards various gases including NO<SUB>2</SUB>, ethanol, acetone, toluene and CO and the results were compared with those of pristine ZnO and ZnO/graphene sensors without MW irradiation. It was demonstrated that the MW irradiated sensor had much higher response particularly to NO<SUB>2</SUB> gas along with superior selectivity and shorter response/recovery times in comparison to unirradiated ZnO/graphene and pristine ZnO sensors. The possible underlying mechanism of this behavior is discussed in detail, mainly in terms of the MW-induced surface defects and the generation of finer ZnO nanoparticles. The results obtained demonstrated the beneficial effect of MW irradiation for enhancing the NO<SUB>2</SUB>-gas sensing behavior of ZnO/graphene nanocomposites, opening a new door not only to a novel synthesis of semiconductors/graphene nanocomposites, but also to a cost-effective way of improving their sensing capabilities.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnO/graphene nanocomposites were prepared by microwave (MW) irradiation. </LI> <LI> MW irradiated sensor had much higher sensing performances particularly to NO<SUB>2</SUB> gas, in comparison to unirradiated ZnO/graphene and pristine ZnO sensors. </LI> <LI> The possible underlying mechanism is explained in terms of the MW-induced surface defects and the generation of finer ZnO nanoparticles. </LI> </UL> </P>

Experience of a pilot-scale hydrogen-producing anaerobic sequencing batch reactor (ASBR) treating food waste

Kim, Dong-Hoon,Kim, Sang-Hyoun,Kim, Ku-Yong,Shin, Hang-Sik Elsevier 2010 International journal of hydrogen energy Vol.35 No.4

<P><B>Abstract</B></P><P>A pilot-scale H<SUB>2</SUB>-producing anaerobic sequencing batch reactor (ASBR) treating food waste was operated. During the operation, the carbon/nitrogen (C/N) ratio was adjusted from 10 to 30 by changing the composition of the food waste. When the C/N ratio was lower than 20, the H<SUB>2</SUB> yield was maintained at around 0.5mol H<SUB>2</SUB>/mol hexose<SUB>added</SUB>, accounting for 2.3% of energy conversion efficiency contained in food waste to H<SUB>2</SUB>, but it gradually dropped at higher C/N ratios. The low performance was accompanied by increased production of lactate, propionate, and valerate. In order to recover the performance, alkaline shock (pH 12.5 for 1day) was imposed on the entire mixed liquor in the fermenter. This alkaline shock method was so effective that the H<SUB>2</SUB> yield significantly increased to over 0.9mol H<SUB>2</SUB>/mol hexose<SUB>added</SUB>, and was then stabilized at 0.69mol H<SUB>2</SUB>/mol hexose<SUB>added</SUB>. In addition, the settling characteristics of H<SUB>2</SUB>-producing ASBR, which was separated into three layers, were investigated. Ribonucleic acid (RNA) as well as volatile suspended solid concentrations of each layer were measured to suggest how to enhance the H<SUB>2</SUB> production in ASBR operation.</P>

Induction of Remission is Difficult due to Frequent Relapse during Tapering Steroids in Korean Patients with Polymyalgia Rheumatica

Kim, Hyoun-Ah,Lee, Jisoo,Ha, You-Jung,Kim, Sang-Hyon,Lee, Chan-Hee,Choi, Hyo-Jin,Baek, Han-Joo,Lim, Mie Jin,Park, Won,Choi, Sungiae,Hong, Yeon-Sik,Lee, Yoo-Hyun,Koh, Bo-Ram,Suh, Chang-Hee The Korean Academy of Medical Sciences 2012 JOURNAL OF KOREAN MEDICAL SCIENCE Vol.27 No.1

<P>Polymyalgia rheumatica is an inflammatory disease affecting elderly and involving the shoulder and pelvic girdles. No epidemiological study of polymyalgia rheumatica was conducted in Korea. We retrospectively evaluated patients with polymyalgia rheumatica followed up at the rheumatology clinics of 10 tertiary hospitals. In total 51 patients, 36 patients (70.6%) were female. Age at disease onset was 67.4 yr. Twenty-three patients (45.1%) developed polymyalgia rheumatica in winter. Shoulder girdle ache was observed in 45 patients (90%) and elevated erythrocyte sedimentation rate (> 40 mm/h) in 49 patients (96.1%). Initial steroid dose was 23.3 mg/d prednisolone equivalent. Time to normal erythrocyte sedimentation rate was 4.1 months. Only 8 patients (15.7%) achieved remission. Among 41 patients followed up, 28 patients (68.3%) had flare at least once. Number of flares was 1.5 ± 1.6. The frequency of flare was significantly lower in patients with remission (<I>P</I> = 0.02). In Korea, polymyalgia rheumatica commonly develops during winter. Initial response to steroid is fairly good, but the prognosis is not benign because remission is rare with frequent relapse requiring long-term steroid treatment.</P>