• Korean Journal of Ecology and Environment
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• v.40 no.2
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• pp.285-293
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• 2007

The study was to determine zonal characteristics of nutrients and chlorophyll and evaluate their trophic relations in Daechung Reservoir. For this study, we compared longterm water quality data among three zones along with trophic state using 1993 to 2002 dataset, obtained from the Ministry of Environment, Korea. Total phosphorous (TP), Secchi depth (SD) and chlorophyll (CHL) showed typical longitudinal declines from the riverine to lacustrine zone, but total nitrogen (TN) was not evident. Largest seasonal variations in TP and CHL occurred during the summer monsoon from July to August. In the reservoir, ambient TN averaged 1.67 mg $L^{-1}$ and ratios of TN : TP averaged 88.04, indicating that nitrogen is not likely limited but phosphorus limitation was evident. Trophic State Index (TSI), based on CHL, TP, and SD, varied depending on the zones and seasons. Mean TSI (TP) in the riverine zone was 62 during the monsoon, indicating a hypertrophic condition, whereas the mean was 40 in the lacustrine, indicating a nearly oligotrophic. Values of TSI (CHL) showed maximum in the transition zone during the monsoon. The deviation analysis of TSI showed that about 65% of TSI (CHL)-TSI (TP) and TSI (CHL)-TSI (SD) values were less than zero and the lowest values were -42, indicating an effect of inorganic turbidity on algal growth in the reservoir. Correlation analysis of CHL vs. SD shewed greater correlation coefficient (p<0.001, r=-0.47) in the transition than other two zones (p<0.001, $r{\leq}-0.40$). Correlation analysis of TP vs. CHL was greatest in the lacustrine and TP was minimum in the lacustrine zone, indicating a lowest yield of algal biomass in the lacustrine. Overall data suggests that zonal response of chlorophyll yield at a given nutrient unit is clearly differed among the longitudinal gradients, so the management strategy such as cross sectional modelling should be provided in each zone.

• Journal of Korean Society of Forest Science
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• v.101 no.1
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• pp.148-157
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• 2012

Korea, with 63.7% of the land being forests, has unique characteristics of forest landscapes coming into view for most residential areas and roads. This study was undertaken with a purpose of supporting forest landscape management by partitioning the areas that landscape management is needed. Through analysing the degree of forest landscape management needs and the visual absorption capability for landscape changes, the zoning process and method for landscape management were conducted. In order to select the areas that are managed by priority for landscape, the degree of forest landscape management needs was quantitatively analyzed with the main scenic sites, travel frequencies, major forest landscape resources, and areas with demand for walking and automobile travel as the basis. The visual absorption capability that means the visual acceptance capability against physical landscape changes of the designated areas was analyzed in order to select the areas that are suitable for artificial landscape management. As a result, it became possible to express the degrees of forest landscape management needs in high, middle, and low sub-areas, and the visual absorption capability in high, middle, and low sub-areas, for each of the three zones in terms of spaces in the forest landscape management areas. For example, among the forest landscape transition zones, if the degree of forest landscape management needs is high and the visual absorption capability is high, then aggressive landscape management would be possible; this would also mean that this area could accept certain levels of physical landscape changes. By applying zoning methods like these, it was possible to attain a conclusive result that proper means of landscape design and management of the forest landscape resources and the surrounding areas could be provided.

• Computers and Concrete
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• v.8 no.2
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• pp.125-142
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• 2011

In the present paper, a numerical simulation method based on mesoscopic composite structure of concrete, the truss network model, is developed to evaluate the diffusivity of concrete in order to account for the microstructure of concrete, the binding effect of chloride ions and the chloride concentration dependence. In the model, concrete is described as a three-phase composite, consisting of mortar, coarse aggregates and the interfacial transition zones (ITZs) between them. The advantage of the current model is that it can easily represent the movement of mass (e.g. water or chloride ions) through ITZs or the potential cracks within concrete. An analytical method to estimate the chloride diffusivity of mortar and ITZ, which are both treated as homogenious materials in the model, is introduced in terms of water-to-cement ratio (w/c) and sand volume fraction. Using the newly developed approaches, the effect of cracking of concrete on chloride diffusion is reflected by means of the similar process as that in the test. The results of calculation give close match with experimental observations. Furthermore, with consideration of the binding capacity of chloride ions to cement paste and the concentration dependence for diffusivity, the one-dimensional nonlinear diffusion equation is established, as well as its finite difference form in terms of the truss network model. A series of numerical analysises performed on the model find that the chloride diffusion is substantially influenced by the binding capacity and concentration dependence, which is same as that revealed in some experimental investigations. This indicates the necessity to take into account the binding capacity and chloride concentration dependence in the durability analysis and service life prediction of concrete structures.

• Journal of Ecology and Environment
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• v.42 no.3
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• pp.103-110
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• 2018

Backgrounds: In arid grasslands, wells are subject to heavy trampling and grazing pressure, which can increase vulnerability to local land degradation. To investigate trampling and grazing, we surveyed plant communities at three well sites in the desert steppe of Mongolia, using 1600-m line transects from the wells. The sites (Bshrub, Sshrub, and shrubL) differed by concomitant shrub type (big shrub, small shrub, and shrub-limited) and livestock pressure (light, medium, and heavy). A plant classification scheme based on edibility and morphology (rosette or creeping type) was used to separate grazing and trampling effects on plant communities. Results: Edible plants were dominant at all sites but a fraction of grazing- and trampling-tolerant plants increased in the order Bshrub, Sshrub, and shrubL, following livestock pressure. Clear transition zones from inedible to edible plant groups were recognized but at different locations and ranges among the sites. Trampling-tolerant plants explained 90% of inedible plants at Sshrub with camels and horses, but grazing-tolerant plants prevailed (60%) at shrubL with the largest livestock number. Plant coverage increased significantly along the transects at Bshrub and Sshrub but showed no meaningful change at shrubL. Herbaceous plant biomass showed significant positive and negative trends at Bshrub and shrubL, respectively. Conclusions: Both grazing and trampling can produce larger fractions of inedible plants; in this, camel and horses can have considerable effects on desert-steppe plant communities through trampling.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.86-88
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• 1997

The detection of the normal zones in the coil winding and the initiation of the proper dump sequence have been one of the most important areas in the superconducting magnet technology. In this paper, the process to derive optimal dump sequence has been investigated through quench simulation and analysis of magnetically coupled superconducting magnet system. The magnet terminal voltage and maximum temperature rise in the quench initiated point are calculated with respect to various input variables such as operation current, dump resistance, etc. The experimental system is comprised of sc solenoidal coil, data aquisition device, external circuit breakers and dump resistor. The quench behavior of the magnet(e.g., temperature profile and the voltage signal) was measured. From this results, theoretical predictions were found to coincide with the experimental observations.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.64-69
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• 2003

Pseudomonas chlororaphis HS21 was isolated from a soil sample and found to produce medium-chain-length polyhydroxyalkanoates (MCL-PHAs) using palm kernel oil (PKO) as the sole carbon source. Up to 3.3 g/1 dry cell weight containing $45\%$ MCL-PHA was produced, when the strain was grown for 21 h in a jar fermentor culture containing 5 g/1 PKO. The polymer produced from PKO consisted of unsaturated monomers of $7.3\%$ 3-hydroxy-5-cis-tetradecenoate and $2.3\%$ 3-hydroxy-5,8,-cis, cis-tetradecadienoate as well as saturated even-carbon number monomers ranging from $C_6\;to\;C_14$, as determined by GC and El GC/MS The PHA was a transparent, sticky material at room temperature. A differential scanning calorimetric analysis revealed that the polymer was amorphous with a $-44^{\circ}C$ glass transition temperature. The number average molecular weight and polydispersity index of the PHA were 83,000 and 1.53, respectively. Although the PHA was practically biodegradable, its degradability was lower than that of poly(3-hydroxyoctanoate) based on a comp:trison of the clear zones formed by growing PHA depolymerase-producing bacteria on an agar plate containing the respective polymers.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.3
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• pp.138-148
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• 2018

Land use regulations introduced for rationalization of land use due to the diversification of socio-economic development, resulting in inconvenience to the people's economic life, have recently changed the paradigm due to deregulation. In this study, the potential areas for urban growth in the Busan area were derived by simulating using the CA model and spatial characteristics were analyzed along with land use regulated areas. The analysis examined whether the land use regulations were actually intended to curb urban growth and promote the efficiency of land use, or if there were other factors that could cause inconvenience to the people's lives. The analysis showed that the greenbelt zones in areas with high development pressure outside urban areas were acting as land use regulations, but there were multiple regulations on land use in many areas. Therefore, it is deemed that various approaches and reviews will be needed, including reconsideration of multiple regulations in areas with high urban growth potential, while maintaining the net function of land use regulations.

• Advances in pediatric surgery
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• v.13 no.1
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• pp.61-65
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• 2007

Conventional treatment of Hirschsprung's disease consists of initial colostomy followed by pull-through operation. But, the treatment of Hirschsprung's disease has been changed along with the development of new surgical technique. Since 1995, endo-GIA has been available at our hospital and one stage Duhamel operation has been performed for neonatal Hirschsprung's disease. Between May 1995 and April 2006, 26 neonates have been treated with one stage pull-through operation by one pediatric surgeon at HanYang University Hospital. The sex ratio was 4.2:1 with male predominance. Clinical findings included abdominal distension (96.2 %), vomiting (50.0 %), delayed passage of meconium (46.2 %), constipation (23.1 %), and enterocolitis (15.4 %). Twenty two cases (84.6 %) were short-segment and 4 cases (15.4 %) were long-segment disease, of which 2 cases were total colon aganglionosis. One of the two patients with total colonic aganglionosis had double transition zones - distal ileum and hepatic flexure of the colon. The average age at operation was $14.56{\pm}8.77$ days and the average weight at operation was $3.26{\pm}0.66kg$. Primary Duhamel operations were performed in 25 patients and Soave-Boley operations was performed in one patient. The endo-GIA 35 (Ethicon, USA) was used from 1995 until 1997, and after that endo-GIA 60 (USSC, USA) was used. The average Duhamel operation time was $88.57{\pm}22.80$ minutes. Wound abscess (n = 2) and septum formation (n =1) occurred after Duhamel operation. Bowel function was normalized in 59 % within 3 months and in 95% within 1 year after operation. There was no mortality after one stage pull-through operation in neonate.

• Journal of the Economic Geographical Society of Korea
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• v.23 no.3
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• pp.229-246
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• 2020

The global environment is rapidly changing due to the Coronavirus outbreak, especially in areas that have been relatively neglected, such as border areas. In particular, In the post-COVID era, the border area between the two Koreas requires a new perception and conceptualization as a space for reconciliation, cooperation and coexistence. Through the status and outlook of post-COVID era, this paper analyzed the promoting directions of each situation, such as SWOT analysis, depending on the characteristics of changes such as domestic preference, changes into standards of new national competitiveness, changes into regional value chains, and the transition to digital economy in the era of the Fourth Industrial Revolution. Based on the previous analysis, this paper proposed realistic approaches such as the utilization of buffer zones, expansion of non-political cooperation to prepare resilience, and promotion of new growth engine industries. In addition, this paper suggested prepared strategies for analyzing the influence of positive and negative cases and responding to them by writing possible scenarios.

• Korean Journal of Materials Research
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• v.12 no.12
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• pp.897-903
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• 2002

Morphological evolution and growth mechanism at the solid/liquid interface during solidification were investigated in the Ni-base superalloy GTD111M by directional soldification and quenching(DSQ) technique. The experiments were conducted by changing solidification rate(V) and thermal gradient(G) which are major solidification process variables. High thermal gradient condition could be obtained by increasing the furnace temperature and closely attaching the heating and cooling zones in the Bridgeman type furnace. The dendritic/equiaxed transition was found in the G/V value lower than $0.05$\times$10{^3}^{\circ}C$s/$\textrm{mm}^2$, and the planar interface of the MC-${\gamma}$ eutectic was found under $17 $\times$ 10{^3}^{\circ}C$ s/$\textrm{mm}^2$. It was confirmed that the dendrite spacing depended on the cooling rate(GV), and the primary spacing was affected by the thermal gradient more than solidification rate. The dendrite lengths were decreased as increasing the thermal graditne, and the dendrite tip temperature was close to the liquidus temperature at $50 \mu\textrm{m}$/s.