• Proceedings of the Korean Vacuum Society Conference
• /
• 1997.07a
• /
• pp.173-176
• /
• 1997

A numerical analysis of the micro-discharge in an AC pplasma dispplay cell has been made using time-deppendent, 2-dimensional multi-fluid equations to understand the discharge pphysics of He-Xe discharge. The time deppendent distribution of the electron tempperature, densities of electrons, various ions and excited sppecies, and the effects fo the wall charge accumulated on the dielectric surface are obtained and comppared with the results of direct observation of time deppendent behavior of VUV and visible sppectra from single discharge cell observed using a gated, image intensified CCD to elucidate the discharge physics.

• Transactions of Materials Processing
• /
• v.9 no.4
• /
• pp.372-378
• /
• 2000

A process model including the effects of both the texture development and ductile damage evolution In plane strain rolling is presented. In this process model, anisotropy from deformation texture and deterioration of mechanical properties due to growth of micro voids are directly coupled Into the virtual work expressions for the momentum and mass balances. Special treatments in obtaining the initial values of field variables in the nonlinear simultaneous equations for the anisotropic, dilatant viscoplastic deformation are also given. Mutual effects of the texture development and damage evolution during plate rolling are carefully examined in terms of the distribution of strain components, accumulated damage, R-value as well as yield surfaces.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 1995.10a
• /
• pp.36-37
• /
• 1995

• Journal of Soil and Groundwater Environment
• /
• v.15 no.3
• /
• pp.61-68
• /
• 2010

Phytoextraction, one type of phytoremediation processes, has been widely used in the removal of heavy metals from polluted soil. This paper reviewed literature on metal uptake by plants and characterized the metal uptake by types of metals (Zn, Cu, Pb, Cd, and As), plant species, initial metal concentrations in soil and the distribution of metals in different parts of plants. The potential of metal accumulation and transport by plants was closely related to plants species, types of metals, and initial metal concentrations in soil. The plants belonging to Brassicaceae, Solanaceae, Poaceae, and Convolvulaceae families have shown the high potential capacity of Cd accumulation. The Gentianaceae, Euphorbiaceae, and Polygonaceae families have exhibited relatively high Pb uptake potential while the Pteridaceae and Cyperaceae families have shown relatively high Zn uptake potential. The Pteridaceae family could uptake a remarkably high amount of As compared with other plant families. The potential metal accumulation per plant biomass has increased with increasing initial metal concentration in soil up to a certain level and then decreased for Cd and Zn. For As, only Pteris vittata had a linear relationship between initial concentration in soil and potential of metal uptake. However, a meaningful relationship for Pb was not found in this study. Generally, the plants having high metal uptake potential for Cd or Pb mainly accumulated the metal in their roots. However, the Euphorbiaceae family has accumulated more than 80% of Pb in shoot. Zn has evenly accumulated in roots and stems except for the plants belonging to the Polygonaceae and Rosaceae families which accumulated Zn in their leaves. The Pteridaceae family has accumulated a higher amount of As in leaves than roots. The types of metals, plant species, and initial metal concentration in soil influence the metal uptake by plants. It is important to select site-specific plant species for effective removal of metals in soil. Therefore, this study may provide useful and beneficial information on metal accumulation by plants for the in situ phytoremediation.

• Toxicological Research
• /
• v.25 no.2
• /
• pp.79-84
• /
• 2009

Cerium oxide nanoparticles (size: 30 nm) were prepared by the supercritical synthesis method, Acute oral toxicity and tissue distribution of the nanoparticles were evaluated by a single administration in rats. Oral administration of the nanoparticles to the rats did not lead to death when the animals were treated by a dose of 5 g/kg (high dose) as well as 100 mg/kg (low dose). Abnormal clinical signs, changes in serum biochemistry and hematology were not observed in high-dose treated group compared to the vehicle control group. Lesions in liver, lung and kidney were not observed in high-dose treated group by histopathological examination. Tissue distribution analysis in liver, kidney, spleen, lung, testis and brain was performed on day 1, day 7 and day 14 after treatment. The average values of the accumulated cerium oxide nanoparticles were elevated in all tissues but statistical significance was only shown in lung. Low levels of tissue distributions after a single oral administration seem to be the low bioavailability of the nanoparticles.

• The Journal of Advanced Prosthodontics
• /
• v.5 no.4
• /
• pp.434-439
• /
• 2013

PURPOSE. The aim of the present study was to evaluate the effects of posts with different morphologies on stress distribution in an endodontically treated mandibular premolar by using finite element models (FEMs). MATERIALS AND METHODS. A mandibular premolar was modeled using the ANSYS software program. Two models were created to represent circular and oval fiber posts in this tooth model. An oblique force of 300 N was applied at an angle of $45^{\circ}$ to the occlusal plane and oriented toward the buccal side. von Mises stress was measured in three regions each for oval and circular fiber posts. RESULTS. FEM analysis showed that the von Mises stress of the circular fiber post (426.81 MPa) was greater than that of the oval fiber post (346.34 MPa). The maximum distribution of von Mises stress was in the luting agent in both groups. Additionally, von Mises stresses accumulated in the coronal third of root dentin, close to the post space in both groups. CONCLUSION. Oval fiber posts are preferable to circular fiber posts in oval-shaped canals given the stress distribution at the postdentin interface.

• Journal of the Korean Society of Safety
• /
• v.25 no.2
• /
• pp.78-83
• /
• 2010

An installation of automated speed enforcement system(ASES) was known for traffic safety and accident preventive effects that traffic characteristics transmute by speed distribution stabilizing. This study is verified the variations of average speed, 85% speed, speed distribution and dispersion as traffic characteristics depend on enforcement system influences in the road. We tested selected 5 areas. By and large, it has a little differences depend on road geometric structure and traffic environment but that is not too much. After all, after automated speed enforcement system installed in all of test areas, average speed, 85% accumulated speed, speed distribution and dispersion characteristics were declined and equalized. The speed dispersion was smaller than before installed the ASES. The speed dispersion value of each case that is the limited speed has been 70Km/h, 80Km/h at flat and straight, 80Km/h at downhill and straight or downhill and left-curved area was 77.3%, 65.2%, 68.7% and 54.1%. Each of the data was declined. We could analyze that average speed distributed depletion factor was declined rapidly by 66.3% in test area.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.22 no.4
• /
• pp.92-100
• /
• 1985

New N+N/P HLE solar cells with N+ surface charge accumulated layer in the emitter region are fabricated on the N/P Si epiwafer by incorporating high fixed positive charge density (Qss) at the Si-AR layer interface. Solar cells are classified into two categories, i.e, OCI and NCI Cell depending on AR layer, SiOl and Si3 N4/sioxynitride layer respectively. The distribution of Qss in the Si-AR layer interface is examined by C-V plot. It shows that the surface charge accumulated layer is formed more effectively in the NCI cell (Qss=1.79-1.84$\times$1012cm-2) than in the OCI cell (Qss=3.03~4.40$\times$1011 cm-2). The efficiency characteristics are evaluated under the JCR halogen lamp of 100 mw/cm2. The average (maximum) conversion efficiency for active area is 15.18 (15.46)% in the OCI cell and 16.31 (17.07)% in the NCI cell.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.15 no.4
• /
• pp.291-297
• /
• 2013

Automated weather stations were installed at 9 locations with, three different elevations, (i.e., 50m, 100m, and 300m a.s.l.) with different slope and aspect in a small watershed ($50km^2$ area). Air temperature at 1500 LST and solar radiation accumulated for 1100-1500 LST were collected from January to December 2012. Topography of the study area was defined by a $30{\times}30$ m digital elevation model (DEM) grid. Accumulated solar irradiance was calculated for each location with the spatially averaged slope and aspect of surrounding circles with 5, 10, 15, 20, 25, and 30 grid cell radii, respectively. The 1500 LST air temperature from clear sky conditions with zero cloud amount was regressed to the 1100-1500 LST solar irradiance at 9 locations. We found the highest coefficient of determination ($r^2$ = 0.544) at 25 grid cell radius and the temperature variation in this study was explained by Y = 0.8309X + 0.0438, where Y is 1500 LST temperature (in $^{\circ}C$) and X is 1100-1500 LST accumulated solar irradiance (in $MJ/m^2$).

• Korean Journal of Environmental Biology
• /
• v.18 no.1
• /
• pp.63-67
• /
• 2000

The effect of $Cd^2+$ on chlorophyll content, water potentials, ion transport, photosynthesis, stomatal apertures and $Cd^2+$ accumulation of organs in Commelina communis was investigated. 3-weeks old Commelina. communis was transferred to and grown in Hoagland solution in the presence or absence of 5 mM $Cd^2+$ for 4 days. $Cd^2+$ was accumulated in all parts of the organs including leaves, roots and stem. The proximity from the root and the age of leaf were significant factors responsible for the distribution of cadmium. Most of $Cd^2+$ was accumulated in the first leaf which was the nearest from the root. $Cd^2+$) accumulation in the leaves led to significant reductions in a series of physiological metabolism. $Cd^2+$ reduced total chlorophyll content up to 70%, and changed chlorophyll a/b ratio to 2. $Cd^2+$ also reduced about 20% of water potential. The treatment of $Cd^2+$ showed about 60% inhibition of photosynthetic activity when measured at various light intensity (100-1,000 $\mu$mol $Em^-2s^-1$). Similar effect was found in terms of stomatal conductance. Therefore, it could be concluded that the treatment of $Cd^2+$ decrease or block various physiological activities. [Cadmium, Photosynthesis, Stomatal conductance].