• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.4
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• pp.176-184
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• 2011

Cold air on sloping surfaces flows down to the valley bottom in mountainous terrain at calm and clear nights. Based on the assumption that the cold air flow may be the same as the water flow, current models estimate temperature drop by regarding the cold air accumulation at a given location as the water-like free drainage. At a closed catchment whose outlet is blocked by man-made obstacles such as banks and roads, however, the water-like free drainage assumption is no longer valid because the cold air accumulates from the bottom first. We developed an empirical model to estimate quantitatively the effect of cold pool on nocturnal temperature in a closed catchment. In our model, a closed catchment is treated like a "vessel", and a digital elevation model (DEM) was used to calculate the maximum capacity of the cold pool formed in a closed catchment. We introduce a topographical variable named "shape factor", which is the ratio of the cold air accumulation potential across the whole catchment area to the maximum capacity of the cold pool to describe the relative size of temperature drop at a wider range of catchment shapes. The shape factor is then used to simulate the density profile of cold pool formed in a given catchment based on a hypsometric equation. The cold lake module was incorporated with the existing model (i.e., Chung et al., 2006), generating a new model and predicting distribution of minimum temperature over closed catchments. We applied this model to Akyang valley (i.e., a typical closed catchment of 53 $km^2$ area) in the southern skirt of Mt. Jiri National Park where 12 automated weather stations (AWS) are operational. The performance of the model was evaluated based on the feasibility of delineating the temperature pattern accurately at cold pool forming at night. Overall, the model's ability of simulating the spatial pattern of lower temperature were improved especially at the valley bottom, showing a similar pattern of the estimated temperature with that of thermal images obtained across the valley at dawn (0520 to 0600 local standard time) of 17 May 2011. Error in temperature estimation, calculated with the root mean square error using the 10 low-lying AWSs, was substantially decreased from $1.30^{\circ}C$ with the existing model to $0.71^{\circ}C$ with the new model. These results suggest the feasibility of the new method in predicting the site-specific freeze and frost warning at a closed catchment.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.1-15
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• 2017

Daecheong Reservoir was made by the construction of a large dam (>15 m in height) on the middle to downstream of the Geum River and the discharge systems have the watergate-spillway (WS), a hydropower penstock (HPP), and two intake towers. The purpose of this study was to investigate the limnological anomalies of turbid water reduction, green algae phenomenon, and oligotrophic state in the lower part of reservoir dam site, and compared with hydro-meteorological factors. Field surveys were conducted in two stations of near dam and the outlet of HPP with one week intervals from January to December 2000. Rainfall was closely related to the fluctuations of inflow, outflow and water level. The rainfall pattern was depended on the storm of monsoon and typhoon, and the increase of discharge and turbidity responded more strongly to the intensity than the frequency. Water temperature and DO fluctuations within the reservoir water layer were influenced by meteorological and hydrological events, and these were mainly caused by water level fluctuation based on temperature stratification, density current and discharge types. The discharges of WS and HPP induced to the flow of water bodies and the outflows of turbid water and nutrients such as nitrogen and phosphorus, respectively. Especially, when hypoxic or low-oxygen condition was present in the bottom water, the discharge through HPP has contributed significantly to the outflow of phosphorus released from the sediment into the downstream of dam. In addition, HPP effluent which be continuously operated throughout the year, was the main factor that could change to a low trophic level in the downreservoir (lacustrine zone). And water-bloom (green-tide) occurring in the lower part of reservoir was the result that the water body of upreservoir being transported and diffused toward the downreseroir, when discharging through the WS. Finally, the hydropower effluent was included the importance and dynamics that could have a temporal and spatial impacts on the physical, chemical and biological factors of the reservoir ecosystem.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.93-98
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• 2017

This experiment investigated characteristic changes in a $Cu_2ZnSnS_4$(CZTS) solar cell by applying a $Zn(O_x,S_{1-x})$ butter layer with various compositions on the upper side of the absorber layer. Among the four single layers such as $Zn(O_{0.76},S_{0.24})$, $Zn(O_{0.56},S_{0.44})$, $Zn(O_{0.33},S_{0.67})$, and $Zn(O_{0.17},S_{0.83})$, the $Zn(O_{0.76},S_{0.24})$ buffer layer was applied to the device due to its bandgap structure for suppressing electron-hole recombination. In the application of the $Zn(O_{0.76},S_{0.24})$ buffer layer to the device, the buffer layer in the device showed the composition of $Zn(O_{0.7},S_{0.3})$ because S diffused into the buffer layer from the absorber layer. The $Zn(O_{0.7},S_{0.3})$ buffer layer, having a lower energy level ($E_V$) than a CdS buffer layer, improved the $J_{SC}$ and $V_{OC}$ characteristics of the CZTS solar cell because the $Zn(O_{0.7},S_{0.3})$ buffer layer effectively suppressed electron-hole recombination. A substitution of the CdS buffer layer by the $Zn(O_{0.7},S_{0.3})$ buffer layer improved the efficiency of the CZTS solar cell from 2.75% to 4.86%.

• Journal of Veterinary Clinics
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• v.26 no.6
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• pp.528-533
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• 2009

In the current study, the mesenchymal stem cells (MSCs) isolated and propagated from the human umbilical cord blood (UCB) were tested for their capabilities of differentiation into chondrocytes in vitro. The mesenchymal progenitor cells (MPCs) collected from UCB were cultured in a low glucose DMEM medium with 10% FBS, L-glutamine and antibiotics. The human MSC colonies were positively stained by PAS reaction. When the immunophenotypes of surface antigens on the MSCs were analyzed by fluorescence-activated cell sorter (FACS) analysis, these cells expressed positively MSC-related antigens of CD 29, CD44, CD 90 and CD105, whereas they did not express antigens of CD14, CD31, CD34, CD45, CD133 and HLA-DR. Following induction these MSCs into chondrocytes in the chondrogenic differentiation medium for 3 weeks or more, the cells were stained positively with safranin O. We clearly confirmed that human MSCs were successfully differentiated into chondrocytes by RT-PCR and immunofluorescent stain of type-II collagen protein. These data also indicate that the isolation, proliferation and differentiation of the hUCB-derived MSCs in vitro can be used for elucidating the mechanisms involved in chondrogenesis. Moreover this differentiation technique can be applied to developing cell-based tissue regeneration or repair damaged tissues.

• Journal of Life Science
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• v.18 no.1
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• pp.1-8
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• 2008

The purpose of this study was to determine the possible additive effects of endurance exercise training (EXER) and selenium (SELE) on the improvements of glucose and lactate transport capacities in diabetic Goto-kakizaki rats. Animals either remained sedentary control (SED) or performed EXER or received SELE [$5{\mu}mol$ kg body wt (-1) day (-1)], or underwent both EXER and SELE (COMBI), which lasted for 6 wk. Compared with sedentary control, EXER alone or the SELE alone group, or the combined treatment group had significant reduction in glucose response measured at 90 min and 120 min during an intraperitoneal glucose tolerance test (IPGTT) and body weight after 6week treatment. EXER alone, or combined group individually had significantly higher glycogen contents in liver compared with SED or SELE groups. EXER alone increased glycogen content in soleus and plantaris compared with SED, and this parameter was increased to greatest extent in the combined treatment groups compared with SED or SELE groups. EXER alone, SELE alone or COMBI, caused significant decreases in the plasma lactates, serum glucose, insulin, total cholesterol and HOMA-IR along with a significant increase in high-density lipoprotein cholesterol compared with SED. In addition, EXER or COMBI individually had significantly lower serum triacylglycerol compared with SED or SELE. With respect to protein expression related to glucose and lactate transport capacities, EXER alone, SELE alone, or COMBI increased in MCT1 and MCT4 protein level in soleus and plantaris. Furthermore, EXER alone, SELE alone or COMBI caused significant increases in mt MCT1 protein level in soleus and plantaris. The findings of the current study suggest that endurance exercise training and selenium treatment may provide therapeutic values to type II diabetic patients with peripheral insulin resistance and hyperlactatecemia by improving glucose and lactate transport capacities, leading to improvements in plasma lactate, serum glucose, insulin and lipid profiles (TC, TG, HDL).

• Korean Journal of Materials Research
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• v.11 no.5
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• pp.367-371
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• 2001

In this paper, theS $r_2$(T $a_{1-x}$ , N $b_{x}$)$_2$ $O_{7}$(STNO) films among ferroelectric materials having a low dielectric constant for metal-ferroelectric-semiconductor field effect transistor(MFS-FET) were discussed. The STNO thin films were deposited on p-type Si(100) at room temperature by co-sputtering with S $r_2$N $b_2$ $O_{7(SNO)}$ ceramic target and T $a_2$ $O_{5}$ ceramic target. The composition of STNO thin films was varied by adjusting the power ratios of SNO target and T $a_2$ $O_{5}$ target. The STNO films were annealed at 8$50^{\circ}C$, 90$0^{\circ}C$ and 9$50^{\circ}C$ temperature in oxygen ambient for 1 hour. The value of x has significantly influenced the structure and electrical properties of the STNO films. In the case of x= 0.4, the crystallinity of the STNO films annealed at 9$50^{\circ}C$ was observed well and the memory windows of the Pt/STNO/Si structure were 0.5-8.3 V at applied voltage of 3-9 V and leakage current density was 7.9$\times$10$_{08}$A/$\textrm{cm}^2$ at applied voltage of -5V.of -5V.V.V.

• Korean Journal of Plant Taxonomy
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• v.35 no.4
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• pp.247-272
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• 2005

The Philadelphus schrenkii complex including P. schrenkii var. schrenkii, P. schrenkii var. jackii, P. schrenkii var. mandshuricus, P. tenuifolius, P. pekinensis, P. seoulensis, P. lasiogynus, and P. scaber, is distributed in China, Korea, japan, and far eastern Russia. Their taxonomic delimitations are obscure because quantitative characters, such as presence/absence and density of hair on leaf, petiole, style, disc, calyx-tube, and pedicel, are highly variable with no apparent characteristics that consistently distinguish from each other within the group. Thus, these morphological characters are reexamined using univariate analyses. P. pekinenesis is distinct from other taxa in having glabrous disk, calyx, pedicel, and leaf blade. In addition, the number of flowers in an inflorescence [(5)7-9(11) vs 5-7 in other taxa], smaller calyx tube [2.5-3 mm vs. (2.5)3-4(5.9) in other taxa], and slightly divided styles help distinguish P. pekinenesis from other related taxa in Korea. However, P. schrenkii var. schrenkii, P. schrenkii var. jackii, P. schrenkii var. mandshuricus, and P. lasiogynus show continuous variation in the pubescence of disk, calyx, pedicel, and leaf blade, and this may reflect a lack of divergence among them. Particular emphases are placed on P. tenuifolius and P. seoulensis, because of the high degree of morphological intergradation with respect to the degree of pubescence in disk, calyx, pedicel, and leaf blade and their inconsistent circumscription across various systematic treatments. P. scaber, distributed in the southern Korea, has often been treated as an independent species having exfoliated branchlets, distinct serrated leaf margin, and recurved styles. However, this current study suggests that P. scaber should be recognized as a form of P. tenuifolius because these distinguishing characters are continuous between P. tenuifolius and P. scaber. In geographical distribution, P. pekinensis is mainly distributed in the southern part of Korea, while P. tenuifoilus and P. schrenkii are commonly found all over the country.

• Journal of the Korean Vacuum Society
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• v.5 no.4
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• pp.371-376
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• 1996

Au films with a thickness around 1600 $\AA$ were deposited onto glass at room temperature by ion beam sputtering with a 5 cm cold-hollow ion gun at pressure $1\times 10^{-6}-1\times 10^{-5}$ Torr. Irradiation of the Au deposited samples was carried out at pressure of $7\times 10^{-6}$ Torr. For the sputter depositions, $Ar^+$ ion energy was 1 keV, and the current density at the substrate surface was 15 $\mu$A/$\textrm{cm}^2$. Effects of 1 keV $Ar^+$ ion dose($I_d$) between $1\times 10^{16}\; and\;2\times 10^{17}\;Ar^+\textrm{cm}^{-2}$on properties such as crystallinity, surface roughness and adhesion, etc. of the films have been investigated. The Au films sputtered by $Ar^+$ ion beam had only (111) plane and the X-ray intensity of the films decreased with increase of $I_d$. The thickness of Au films reduced with Id. $R_{ms}$ surface roughness of the films increased from 16 $\AA$ at as-deposited to 1118 $\AA$ at ion dose= $2\times 10^{17}\;Ar^+\textrm{cm}^{-2}$. Adhesion of Au film on sputtered at $I_d$= $2\times 10^{17}\;Ar^+\textrm{cm}^{-2}$ was 9 times greater than that of Au film with untreated, as determined by a scratch test.

• Journal of the Korean Geographical Society
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• v.31 no.1
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• pp.1-18
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• 1996

This study examines the spatial characteristics of postal office patronage in rural areas. in the light of future possible relocation and closures of the postal facilities. Most of private services have flown out small rural central places due to the decrease of supporting population, and there consequently remain only a few public services including government-run post offices at the Myon seats, the lowest level among rural central places in Korea. The small local population and its further decline undermine the rationale for maintaining such public services in depleted rural areas. For the worse of it, the government recently plans to transform the postal system to a quasi-private, corporational structure. One can fear that the profit-seeking nature of the new postal corporation will inevitably force to close many of such small rural facilities. The study first analysed nation-wide censuses of postal offices for the years of 1986 and 1992. The postal services examined are per capita number of postal stamps and revenue stamps sold, and letters, parcels, telegrams and monetary transactions handled at the post offices. It is found that, while the usage of postal services has increased substantially throughout the nation during the period of 1986-1992, the increment has largely been occurred by urban post offices rather than by those in Gun seats (i.e., rural counties); and that the gap of the service levels between urban and rural post offices is ever widening. The study further examined the service differentials among the post offices within rural counties to find that those post offices adjacent to the county (Gun) seats and larger urban centers rendered less amount of services than remote rural post offices, indicating that rural residents tend to partonize larger centers more and more than local Myon seats. At the second stage of the study, questionnaire surveys were conducted in Muju, Kimpo, and Hongsung-Gun's. These three counties are meant to represent respectively the remote, suburban, and intermediary counties in Korea. The analyses of survey data reveal that the postal hinterlands of the county seats extend to much of nearby Myons, the subdivisions of a Gun. It is also found that the extent of postal hinterlands of the three counties and the magnitude of patronage and quite different from each other depending upon the topography, population density, and the propinquity of the counties to metropolitan centers. The findings suggest to reappraise the current flat allocation scheme of public facilites to each of rural subdivisions throughout the nation. A detailed analysis on the travel behavior of the survey respondents yields that age is the most salient variable to distinguish activity spaces of rural residents. The activity spaces of older respondents tend to be more limited within their Myon, whereas those of younger respondents extend across the Myon boundary, toward the central towns and even distant larger cities. The very existence of several activity spaces in rural areas calls for an attention in the future locational decisions of public facilities. The locational criteria, employed by the Ministry of Communication of Korean government to establish a post office, are the size of hinterland population and the distance from adjacent postal facilities. The present study findings suggest two additional criteria: the order in rural central place hierarchy and the propinquity to the upper-level centers of the central hierarchy. These old and new criteria are complementary each other in that the former criteria are employed to determine new office locations, whereas the latter are appropriate to determine facility relocation and closures.

• Journal of Environmental Policy
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• v.4 no.1
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• pp.93-111
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• 2005

Defining soil quality in scopes and applications is one of the prerequisite for the sustainable management of soil environment to orient researches, strategies and policies. However, definition of soil quality is controversial depending upon a viewpoint of soil science or soil environment. Soil quality can be, irrespective of the disciplines, defined as the capacity of a soil to function within ecosystem boundaries to sustain biological productivity, maintain environmental quality and promote plant and animal health. Common to all of the soil quality concepts can be summarized as the capacity of soil to function effectively at present and in the future. The OECD includes soil quality as one of the agri-environment indicators. This article intends to i) summarize the current soil quality research, and ii) provide information on protocol of soil quality assessment. A framework for soil quality was divided into three steps: indicator selection as minimum data set (MDS), scoring of the selected indicators, and integration of scores into soil quality index. Korean government suggested possible physical and chemical indicators such as bulk density and organic matter for paddy and upland soils to OECD. The framework of soil quality assessment is not yet implemented in Korea. Countries such as USA, Canada and New Zealand have constructed the framework on soil quality assessment and developed a user-friendly version of soil quality assessment tools to evaluate the integrated effects of various soil management practices. The protocol provided in this review might help policymakers, scientists, and administrators improve awareness about soil quality and understand the way of soil environment management.