• Journal of Environmental Impact Assessment
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• v.25 no.6
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• pp.369-383
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• 2016

A distributed watershed model CAMEL(Chemicals, Agricultural Management and Erosion Losses) was applied to a part of grazing grassland and vegetation buffer strip(VBS) located in Daegwanryeong, Korea. A set of scenario analyses was carried out for grassland and VBS with various combinations of VBS widths, soil textures and ground surface slopes. The simulation results indicate that annual direct runoff decreases with wider VBS and the removal efficiency of pollutants generally decrease with steeper slopes. The removal efficiency of sediment is not significantly different with VBS widths. For gentle and medium slopes($10^{\circ}$, $20^{\circ}$), the removal efficiency of TOC and TN is not significantly different with VBS widths. As for a steep slope($30^{\circ}$), however, the removal efficiency of TOC and TN increases with narrower VBS. The removal efficiency of TP is generally high except for medium and steep slope of sandy loam where the removal efficiency of TP increases with wider VBS. This result of TP is contrary to the results of TOC and TN due to the adsorption characteristics of phosphorus associated with fine sediment particles. It is expected that CAMEL can be used for evaluating the effectiveness of VBS to reduce non-point source pollution discharges.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2005.04a
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• pp.85-101
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• 2005

This study was carried out a field survey and review articles to investigate a characteristic of the distribution pattern in Korean endemic Corylopsis coreana. Distribution of Corylopsis coreana was found from Boseung-gun, Gwangyang-si, Suncheon- si, Jeumanl-myeon Goheung-gun, Ganjeon-myeon Gurye-gun, Mt. Cheongwan Jangheung-gun, Nogodan Mt. Jiri in Jeollanam-do, Mt. Cheonhwang Namwon-si and Beamsagol and Banyabong Mt. Jiri, in Jeollabuk-do, Sancheong-gun, hadong-gun and Namhea-gun in Gyeongsangnam-do and Mt. Backun, Pocheon-si in Gyeonggi-do. Total flora in the distribution region of Coryloplsis coreana were recorded as 242 taxa; 70 families, 159 genus, 216 species, 22 varieties, 4 forma. Ratio of taxonomic categories was consisted of Pteridophyte $5.8\%$, Gymnosperm $3.7\%$, Dicotyledon $18.6\%$ and Monocotyledon $71.9\%$. Ratio of Life cycle styles was Annual $1.7\%$ and Perennial $98.3\%$. Ratio of growth habit was appeared to Herb $44.2\%$, Vine $12.4\%$, Shrub $17.8\%$ and Tree $25.6\%$. The distribution region of Corylopsis coreana found to typical type which distribute in N, NE or NE slope. The native Corylopsis coreana of Sinjeonri Sungju-eup in Jellanam-do appeared to a declining tendency which caused by influence of tree lager.

• Journal of Bio-Environment Control
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• v.7 no.2
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• pp.91-108
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• 1998

This study was carried out to survey basic information of swine farms on the machine holdings. facility type. management of manure by farm scale and operation, and then to develop the mechanization model. Manual feeding was common for sows and nursing sows. but automation feeding was normally furnished for weaners. growing pigs and castrated male pigs. Water supplies was completely automated for all of the surveyed swine farms. Fully mechanized and automated system would not be feasible and affordable for the small scale farms breeding less than 500 heads. Because the environmental control for the nursing sows and weaner was important, some swine houses were constructed with the windowless type. However, the furnished rates ranged from 22.2% to 44.4% of the surveyed nursing sow and weaner houses at the farm scales. In the future, a computerized ventilation system would be commended for the efficient use of heat energy and to maintain the desirable temperature of swine buildings. Over-investment for large scale farm and over-crowded pigpen of small farm would cause wasting construction expenses and spreading epidermic diseases Hence, the size of swine building should follow the recommended scale. The fermentation drier was recommended for the manure management. Urine could be recycled or discharged after treating by the activated sludge process.

• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.756-762
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• 1997

The experiment was carried out to fabricate alumina membrane which has a cylindrical pore structure by anodizing aluminium plate in sulfuric acid solution with the electrochemical technique. The aluminium plate for anodizing was prepared by the pretreatment process such as chemical, electro-polishing and thermal treatment. The pore size distribution and the film thickness of alumina membrane were investigated by the implementation of scanning electron microscope(SEM) and BET method. The results show that the oxide film has a geometrical structures like a Keller model and that the membrane has a uniform pore distribution. The pore size and the oxide film thickness are dependent on the anodizing process variables such as the electrolyte concentration, the reation temperature and the anodizing current density.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.924-925
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• 2011

본 논문에서는 환경친화적이고, 인화점 및 발화점이 높아 화재의 위험도가 낮은 식물성 절연우를 기존 변압기의 광유를 대체로 사용하기 위한 열적 특성을 열유동해석을 이용하여 온도분포를 수치해석을 통하여 예측하였다. 해석모델로는 154kV 급 단상 내철형 유입자냉식 변압기를 대상으로 CFD 해석을 수행하였으며, 광유와 식물성 절연유는 부하의 변화에 따른 온도특성을 파악하는 동시에 핫스팟(hot spot)을 예측하였다. 본 논문은 변압기를 3차원 모델링하여 유동 및 온도 분포를 해석한 결과, 변압기의 내부 온도 및 핫스팟 추적에 대하여 변압기의 수명에 대한 예측이 가능하며, 식물성 절연유를 사용한 전력용 변압기 온도 분포 해석결과는 식물성 절연유의 적용 및 냉각 설계 변경에 기초자료롤 활용될 것이다.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.3
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• pp.22-34
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• 1996

Regarding the plate bending process by line heating method, in this study a simplified numerical analysis is performed for a beam model to predict its residual deformation and stress distribution. Using the modified strip theory and beam finite element method, a PC-based simulation program is developed for a thermo-elastic-plastic beam. The plate bending problem can be approximately replaced by a beam model using distributed springs to account for the effect of adjacent strips. The spring constants are chosen as the best fit with experiments. In this paper, it is assumed that the temperature distribution is already given and the temperature-dependent material properties are considered. To verify the simulation program, the results using present numerical algorithm are compared with other published experimental results and similar numerical studies. The comparison shows good agreement. The present PC-based computer program also shows good efficiency in computing time.

• Tunnel and Underground Space
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• v.9 no.4
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• pp.306-314
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• 1999

In underground spaces including nuclear waste repository, prediction of air quantity, temperature/humidity and pollutant concentration is utmost important for space construction and management during the normal state as well as for determining the measures in emergency cases such as underground fires. This study aims at developing a model for underground space environment which has capabilities to take into account the effects of autocompression for the natural ventilation head calculation, to find the optimal location and size of fans and regulators, to predict the temperature and humidity by calculating the convective heat transfer coefficient and the sensible and latent heat transfer rates, and to estimate the pollutant levels throughout the network. The temperature/humidity prediction model was applied to a military storage underground space and the relative differences of dry and wet temperatures were 1.5 ~ 2.9% and 0.6 ~ 6.1%, respectively. The convection-based pollutant transport model was applied to two different vehicle tunnels. Coefficients of turbulent diffusion due to the atmospheric turbulence were found to be 9.78 and 17.35$m^2$/s, but measurements of smoke and CO concentrations in a tunnel with high traffic density and under operation of ventilation equipment showed relative differences of 5.88 and 6.62% compared with estimates from the convection-based model. These findings indicate convection is the governing mechanism for pollutant diffusion in most of the tunnel-type spaces.

• Journal of Korean Society of Forest Science
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• v.107 no.2
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• pp.140-150
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• 2018

For the estimation of greenhouse gas dynamics in forests, it is useful to use a model which simulates both carbon (C) and nitrogen (N) cycle simultaneously. A forest C model, called FBDC, was developed and validated in Korea. However, studies on development of forest N model are insufficient. This study aimed to suggest a development process of a forest C and N model. We analyzed the general features, structures, ecological processes, input data, output data, and methods of integrating C and N cycles of the VISIT, Biome-BGC, Forest-DNDC, and O-CN. The structure and features of the FBDC were also analyzed. The VISIT was developed by integrating forest C model with a N cycle module, and the new model also could be designed by combining the FBDC with a N cycle module. The VISIT and Forest-DNDC could estimate soil $N_2O$ emissions, and the integrated model should include the processes shared by these models. Especially, the overseas models linked C and N cycles based on N absorption, C absorption, and decomposition of dead organic matter. Therefore, the integration of the FBDC with N cycle module should apply this linkage of structures between C and N cycles. Climate, soil texture, and species distribution data, which are essential for the model development, were available in Korea. However, parameter data associated with N cycle and validation data for soil $N_2O$ emissions need to be obtained by field studies.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.7
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• pp.535-543
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• 2014

A computational simulation for a nonslender BWB UCAV configuration with rounded leading edge and span of 1.0m was performed to analyze its aerodynamic characteristics. The freestream is 50m/s over -4 to 26 degree A.o.A.s. Reynolds number based on the mean chord length is $1.25{\times}10^6$. 3D multi block hexahedral grids are used which allow good grid quality and ease to capture boundary layer. ${\gamma}-Re_{\theta}$ model as well as $k-{\omega}$ SST model is employed to assess the effect of transition for flow behavior. Drag and lift of the UCAV were well predicted while $C_M$ is under predicted at high angle of attacks and influenced by the turbulence models strongly. After assessing pressure distribution, skin friction lines and velocity field around the UCAV configuration, it was found that transition effect should be considered to enhance the prediction of aerodynamic behavior by a vortical flowfield.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1281-1293
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• 2013

A sophisticated finite element model is illustrated to analyze the behavior of Prefabricated Parallel Wire Strand(PPWS) sockets for main cables of suspension bridges. An orthotropic model is proposed for the casting material by considering both effects of individual wires and a casting alloy, and the contact between surfaces of a socket and a casting alloy is idealized by using the Coulomb friction and the surface-based contact model. The proposed FE model is verified by comparing the strain distributions obtained from the tensile test and FE analysis. The mechanical behavior of a socket is investigated with respect to the variation of the frictional coefficient. The result shows that the friction between surfaces significantly diminishes the stress concentration of a socket and a casting alloy, and the normal stress from the design equation represents the averaged value of the upper and lower quartiles in the distribution of contact stresses between a socket and a casting alloy.