• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.262.1-262.1
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• 2014

Lipid peroxidation induces functional deterioration of cell membrane and induces cell death in extreme cases. These phenomena are known to be related generally to the change of physical properties of lipid membrane such as decreased lipid order or increased water penetration. Even though the electric property of lipid membrane is important, there has been no report about the change of electric properties after lipid peroxidation. Herein, we demonstrate the molecular energy band change in red blood cell membrane through peroxidation by air-based atmospheric pressure DBD plasma treatment. Ion-induced secondary electron emission coefficient (${\gamma}$ value) was measured by using home-made gamma-focused ion beam (${\gamma}$-FIB) system and electron energy band was calculated based on the quantum mechanical Auger neutralization theory. The oxidized lipids showed higher gamma values and lower electron work functions, which implies the change of surface charging or electrical conductance. This result suggests that modified electrical properties should play a role in cell signaling under oxidative stress.

• Elastomers and Composites
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• v.44 no.3
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• pp.274-281
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• 2009

Nylon 6 and nylon elastomer were prepared by anionic polymerization route. Nylon elastomers, composed of hard segment of polyamide(PA) and soft segment of polyether(PE), were synthesized by use of TDI terminated polyol with caprolactam. The morphology of the electrospun webs of nylon and nylon elastomers, observed by FE-SEM, showed that the porous electrospun web was composed of nanofibers, whose diameter were in the range of 100 to 180 nm. Their behavior of melting and crystallization and the chemical structure of nylon elastomers were investigated by DSC and ATR FT-IR. Result of tensile testing indicated that nylon has higher tensile strength and lower elongation than nylon elastomers. Atmospheric plasma(APP) with $O_2$ and $N_2$ as reactive gas modified the surface of electrospun nylon and electrospun nylon elastomers allowing them higher hydrophilicity, while APP with $CH_4$ as reactive gas modified the surface of polymers allowing higher hydrophobicity.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.2
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• pp.196-205
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• 2008

Variability in vertical ozone and meteorological profiles was measured by 2Z electrochemical concentration cells (ECC) ozonesonde at Bangyi in Seoul ($37.52^{\circ}N$, $127.13^{\circ}E$) during June $6{\sim}9$, 2003 in odor to identify the vertical distribution of ozone and its relationship with the lower-atmospheric structure resulted in the high ozone concentrations near the surface. The eight profiles obtained in the early morning and the late afternoon during the study period clearly showed that the substantial change of ozone concentrations in lower atmosphere(${\sim}5\;km$), indicating that it is tightly coupled to the variation of the planetary boundary layer (PBL) structure as well as the background synoptic flow. All profiles observed early in the morning showed very low ozone concentrations near the surface with strong vertical gradients in the nocturnal stable boundary layer due to the photochemical ozone loss caused by surface NO titration under very weak vertical mixing. On the other hand, relatively uniform ozone profiles in the developed mixing layer and the ozone peaks in the upper PBL, were observed in the late afternoon. It was noted that a significant increase in ozone concentrations in the lower atmosphere occurred with the corresponding decrease of the mixing height in the late afternoon on June 8. Ozone in upper layer did not vertically vary much compared to that in PBL but changed significantly on June 6 that was closely associated with the variation of synoptic flows. Interestingly, heavily polluted ozone layers aloft (a maximum value of 115 ppb around 2 km) were formed early in the morning on 6 through 7 June under dominant westerly synoptic flows. This indicates the effects of the transport of pollutants on regional scale and consequently can give a rise to increase the surface ozone concentration by downward mixing processes enhanced in the afternoon.

• Atmosphere
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• v.20 no.4
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• pp.505-518
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• 2010

We investigated the impacts of the diabatic heating location, vertical profile and basic state on the Rossby wave propagation. To examine the dynamical process of individual responses on the regional heat source, a dry version of the linear baroclinic model was used with climatological summertime (JJA) mean basic state and vertical structure of the diabatic heating for 1979-2008. Two sets of diabatic heating were constructed of those positioned in the mid-latitudes (Tibetan Plateau, eastern Mediterranean Sea, and the west-central Asia) and the tropics (the southern India, Bay of Bengal, and western Pacific). It was found that using the principal component analysis, atmospheric response to diabatic heating reaches to the steady state in 19th days in time. The prescribed mid-latitude forcing forms equivalent barotropic Rossby wave propagation along the westerly Asia jets, whereas the tropical forcing generates the Rossby wave train extending from the tropics to mid-latitudes. In relation to the maximum vertical profile, the mid-level forcing reveals a stronger response than the lower-level forcing, which may be caused by more effective Rossby wave response by the upper-level divergent flow. Under the different sub-seasonal mean state, both of the tropical and mid-latitude forcing induce the different sub-seasonal response intensity, due to the different basic-state wind.

• Corrosion Science and Technology
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• v.21 no.1
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• pp.1-8
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• 2022

The use of cathodic protection for metals can be achieved by sacrificial anode CP or impressed current CP, or a combination of both. Cathodic protection is a highly effective anti-corrosion technique for submerged metals or metals in soil. But because the non-immersion atmospheric automobile environment is a high resistance environment, it is limited by fundamental cathodic protection. However, the application of cathodic protection to automobiles is attractive because of the possibility of maintaining corrosion resistance while using lower-cost materials. A commercially available product for automobiles that uses both sacrificial anode CP and impressed current CP was tested in a periodic salt spray environment to investigate the performance of the devices. Experimental results show that the metal to be protected has different anti-corrosion effects depending on the distance from the anode of the device, but it is effective for the entire 120 cm long specimen exposed with one anode. The cathodic protection is effective because the conductive tape attached to the anode of the structure to be protected acts as a constant electrolyte in wet and dry conditions. The results show that the entire standard passenger car can be protected by cathodic protection with 4 anodes.

• Korean Journal of Materials Research
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• v.30 no.7
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• pp.338-342
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• 2020

Tin oxide (SnO₂) nanocrystals are synthesized by a thermal evaporation method using a mixture of SnO₂ and Mg powders. The synthesis process is performed in air at atmospheric pressure, which makes the process very simple. Nanocrystals with a belt shape start to form at 900 ℃ lower than the melting point of SnO₂. As the synthesis temperature increases to 1,100 ℃, the quantity of nanocrystals increases. The size of the nanocrystals did not change with increasing temperature. When SnO₂ powder without Mg powder is used as the source material, no nanocrystals are synthesized even at 1,100 ℃, indicating that Mg plays an important role in the formation of the SnO₂ nanocrystals at temperatures as low as 900 ℃. X-ray diffraction analysis shows that the SnO₂ nanocrystals have a rutile crystal structure. The belt-shaped SnO₂ nanocrystals have a width of 300~800 nm, a thickness of 50 nm, and a length of several tens of micrometers. A strong blue emission peak centered at 410 nm is observed in the cathodoluminescence spectra of the belt-shaped SnO₂ nanocrystals.

• Journal of Energy Engineering
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• v.14 no.1
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• pp.1-10
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• 2005

The combustion reactivity of char depending on the pyrolysis pressure was investigated with Pressurized Thermogravimetric Analyser. The amounts of volatiles released at pyrolysis pressure of 1, 8 and 15 atm were, first, measured with Alaska, Adaro and Denisovsky coals. Reactivities of chars produced at var-ious pyrolysis pressure were evaluated at atmospheric pressure and 500℃, and analysed in terms of char crystal structure, surface area, pore characteristics and chemical composition of char. Finally, the combustion reactivities of three chars were examined at pressure of 1 atm, 8 atm and 15 atm. From this study, it was recognized that the amount of volatiles released decreases with increase in pyrolysis pressure, and reaction rate of char produced at higher pyrolysis pressure was lower than that at lower pyrolysis pressure. It might be resulted from the difference in char surface area and pore characteristics rather than char crystal structure and chemical characteristics. At 15 atm, kinetic parameters of Alaska char were obtained with the grain model, and these were 56.8 KJ/mole for activation energy and 222.34 (1/min) for frequency factor.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.41-50
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• 2006

The crustal structure of Korean Peninsula have been investigated by analyzing group velocity dispersion data of surface wave. Cross.correlation of seismic background motions (Campillo and Paul, 2003; Shapiro et al., 2005) has been applied to estimate the short.period Rayleigh. and Love.wave group velocity dispersion characteristics of the region. Standard processing procedures were applied to the cross.correlation, except that signal whitening was used in place of one.bit sampling equalize power in signals from different times. Multiple.filter analysis was used to extract the group velocities from the estimate Green's functions, which were then use to image the spatially varying dispersion at periods between 0.5 and 20 seconds. The tomographic inversion technique used inverted all periods simultaneously to provide a smooth dispersion curve as a function of period in addition to the usual smooth spatial image for a given period. The Gyeongsang Basin in the southeastern part of the peninsula is clearly resolved with lower group velocities.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.2
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• pp.298-317
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• 2019

The physical characteristics of the Ulleung Warm Eddy (UWE) and its relationship with the East Korea Warm Current (EKWC) were analyzed using the CMEMS (Copernicus Marine Environment Monitoring Service) satellite altimetry data and the CTD data of the National Institute of Fisheries Science (NIFS) near the Ulleung Basin from 1993 to 2017. The distribution of the UWEs coupled with EKWC accounts for 81% of the total number of the UWEs. Only 7% of the total eddies are completely separated from the EKWC. The UWE has the characteristics of high temperature and high salinity water inside of it when it is formed from the EKWC. However, when the UWE is wintering, its internal structure changes greatly. In the winter, surface homogeneous layer of $10^{\circ}C$ and 34.2 psu inside of the UWE is produced by vertical convection from sea-surface cooling, and deepened to a maximum depth of approximately 250 m in early spring. In summer, the UWE changes into a structure with a stratified structure in the upper layer within a depth of 100 m and a homogeneous layer made in winter in the lower layer. 62 UWEs were produced for 25 years from 1993 to 2017. on average, 2.5 UWEs were formed annually, and the average life span was 259 days (approximately 8.6 months). The average size of the UWEs is 98 km in the east-west direction and 109 km in the north-south direction. The average size of UWE using satellite altimetric data is estimated to be 1~25 km smaller than that using water temperature cross-sectional data.

• Journal of the Korean earth science society
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• v.35 no.1
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• pp.54-68
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• 2014

In order to analyze the land surface properties in Seoul and its surrounding metropolitan area, several indices and land surface temperature were calculated by the Landsat satellites (e.g., Landsat 5, Landsat 7, and Landsat 8). The Landsat data came from only in the fall season with Landsat 5 on October 21, 1985, Landsat 7 on September 29, 2003, and Landsat 8 on September 16, 2013. The land surface properties used are the indices that represented Soil Adjusted Vegetation Index (SAVI), Modified Normalized Difference Wetness Index (MNDWI), Normalized Difference Wetness Index (NDWI), Tasseled cap Brightness, Tasseled cap Greenness, Tasseled cap Wetness Index, Normalized Difference Vegetation Index (NDVI) and Normalized Difference Built-up Index (NDBI) and the land surface temperature of the area in and around Seoul. Most indices distinguish very well between urban, rural, mountain, building, river and road. In particular, most of the urbanization is represented in the new city (e.g., Ilsan) around Seoul. According to NDVI, NDBI and land surface temperature, urban expansion is displayed in the surrounding area of Seoul. The land surface temperature and surface elevation have a strong relationship with the distribution and structure of the vegetation/built-up indices such as NDVI and NDBI. While the NDVI is positively correlated with the land surface temperature and is also negatively correlated with the surface elevation, the NDBI have just the opposite correlations, respectively. The NDVI and NDBI index is closely associated with the characteristics of the metropolitan area. Landsat 8 and Landsat 5 have very strong correlations (more than -0.6) but Landsat 7 has a weak one (lower than -0.5).