정광욱 Jung Kwang Wook , 윤춘경 Yoon Chun Gyeong , 이인호 Lee In Ho , 이승일 Lee Seung Il , 강수만 Kang Su Man , 함종화 Ham Jong Hwa

DOI: JKWST Vol.56(No.1) 1-9, 2014

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Sediment pollutants have been considered an important source for the eutrophication of estuarine reservoir. In this study, the effects of pollutants released from bottom sediment to water column were investigated. Sediment samples were collected each two station from Namyang and Sukmoon estuarine reservoirs in August 2013. The fractionation result of sediment phosphorus indicated that Adsorbed-P (36.7±8.84 %) and Nonapatite-P (29.3±12.50 %) are the two dominant phosphorus groups in the sediments. For sediment release test, eight sets of acrylic chamber (0.3 m diameter×1 m high, with 0.15 m sediment depth) were used with aerobic and anaerobic environment. Under anaerobic conditions, rates of NH4-N release from the sediments were highly variable, with final concentrations of NH₄-N in the overlying water varying from between about 0.69～1.04 in Namyang and 2.58～4.23 mg/L in Sukmoon reservoir. The NH₄-N release was active at the upstream around the confluence of tributary compared to downstream near the embankment. The PO₄-P release was more obvious than NH₄-N in anaerobic condition. The final PO₄-P concentrations were approximately from two-fold to eight-fold higher than initial concentration. In terms of reservoir water quality management, not only tributary pollutants but also sediment nutrient loading is necessary to consider the water quality contribution.

이형진 Lee Hyungjin , 김태곤 Kim Taegon , 이정재 Lee Jeongjae , 서교 Suh Kyo

DOI: JKWST Vol.56(No.1) 11-20, 2014

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Many classification studies for the community of densely-connected nodes are limited to the comprehensive analysis for detecting the communities in probabilistic networks with nodes and edge of the probabilistic distribution because of the difficulties of the probabilistic operation. This study aims to use convolution method for operating nodes and edge of probabilistic distribution. For the probabilistic hierarchy network with nodes and edges of the probabilistic distribution, the model of this study detects the communities of nodes to make the new probabilistic distribution with two distribution. The results of our model was verified through comparing with Monte-carlo Simulation and other community-detecting methods.

김태완 Kim Tae-wan , 손영환 Son Young-hwan , 박재성 Park Jae-sung , 노수각 Noh Soo-kack , 봉태호 Bong Tae-ho

DOI: JKWST Vol.56(No.1) 21-30, 2014

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The objective of this study is to find the electrical properties of Bottom ash from thermoelectric power plants in Korea. By using Parallel Plate Method, the electrical resistivity and dielectric constant were measured at the frequency from 20 Hz to 10 MHz. Also, unconfined strength test, XRF and sieve analysis were performed for finding the relationship between strength, physiochemical properties and electrical properties. In the result, the change of electrical resistivity and dielectric constant of bottom ash against frequency was similar to that of general soil. The proportion of fine grain in bottom ash had the positive correlation with dielectric constant and negative correlation with electrical resistivity. Chloride and sulfur trioxide were proportional to dielectric constant and the more bottom ash had chloride content, the lower electrical resistivity appeared in bottom ash. Unconfined strength of bottom ashes had a range from 200 kPa to 780 kPa and strength was inverse proportional to electrical resistivity.

은코모제피템바 Nkomozepi Temba , 정상옥 Chung Sang-ok

DOI: JKWST Vol.56(No.1) 31-40, 2014

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서일환 Seo Il-hwan , 이인복 Lee In-bok , 문운경 Moon Oun-kyung , 권경석 Kwon Kyeong-seok

DOI: JKWST Vol.56(No.1) 41-49, 2014

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Pig chronic wasting disease, including porcine reproductive and respiratory syndrome (PRRS) and postweaning multisystemic wasting syndrome (PMWS), have made a continuous economic damage in pig farms. Airborne spread of livestock viruses are an important spread factor which is difficult to analyze due to invisible airflow and limitation of measurement. The objective of this study is to analyze airborne disease spread between buildings in the experimental pig farm by means of field experiment and computational fluid dynamics (CFD). The field experiments were conducted to capture airborne virus using air sampler and teflon filter along multi points in the experimental pig farm. The samples were tested in terms of virus detection resulting in positive reaction for PRRS and PCV-2 viruses, which can be a firm evidence of airborne virus spread. The CFD simulation model was developed by considering complex topography, wind conditions, building arrangement, and ventilation systems and was used to analyze airborne virus spread according to different wind conditions. The CFD computed result showed a possibility of airborne virus spread via livestock aerosol from infected pig house to neighboring pig houses according to wind directions. The CFD simulation technique is expected to provide significant data for estimating and making a counterplan against airborne disease spread.

정영훈 Jung Younghun , 문종필 Moon Jongpil , 이승오 Lee Seung Oh , 박윤식 Park Youn Shik

DOI: JKWST Vol.56(No.1) 51-59, 2014

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민슬기 Min Seul-gi , 손영환 Son Young-hwan , 노수각 Noh Soo-kack , 박재성 Park Jae-sung , 봉태호 Bong Tae-ho

DOI: JKWST Vol.56(No.1) 61-70, 2014

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South Korea is under pressure to reduce CO₂ emissions because of expanding request for reducing CO₂ emissions. In many industry sectors, CO₂ emissions were analyzed to reduce CO₂ emissions. But little effort in researching agricultural sector has been undertaken because it is recognized as environmentally friendly industry. The object of this research is to estimate CO₂ emissions of crops and analysis on correlation between CO₂ emissions and production, acreage of crops. In this study, environmental input-output analysis was used to estimate CO₂ emissions of agricultural sector and spearman correlation coefficient was used to analysis on correlation between CO₂ emissions and statics like production and acreage. As a result, rice, barley, pulses and horticultural specialities had correlation with acreage and correlation coefficients of these crops were 0.800∼0.933. Regression equations about CO₂ emissions and acreage of rice, barley, pulses and horticultural specialities was made and R² of these equations were 0.615∼0.929. Using equations, CO₂ emissions of rice, barley, pulses and horticultural specialities can be estimated with acreage.

노재진 Noh Jae Jin , 이달원 Lee Dal Won

DOI: JKWST Vol.56(No.1) 71-79, 2014

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In this study, an experiment with large-scale model was performed according to raising the embankment in order to investigate the behavior of failure for embankment and spillway transitional zone due to overtopping. The pore water pressure, earth pressure, settlement and failure pattern by a rapid drawdown and overtopping were compared and analyzed. The pore water pressure and earth pressure at spillway transitional zone by overtopping increased a rapidly with the expansion of seepage erosion, but the crest showed a smally change due to effect of the inclined core type. And it is considered an useful data that can accurately estimate the possibility of failure of the reservoirs. A settlement at overtopping decreased a rapidly due to failure of crest. The relative settlement difference due to change of the water level at the upstream and downstream slope cause increase largely crack of crest. The behavior of failure by overtopping was gradually enlarged towards reservoirs crest from the bottom of the spillway transition zone, the inclined core after the raising the embankment was influenced significantly to prevent the seepage erosion.

노현석 Roh Hyun-seok , 서일환 Seo Il-hwan , 이인복 Lee In-bok

DOI: JKWST Vol.56(No.1) 81-88, 2014

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Accurate wind data is essential for predicting airborne spread of virus. OpenFOAM was used for computational fluid dynamics (CFD) simulation procedure which is under GNU GPL (General Public License). Using complex terrain, DEM (Digital Elevation Map) that was prepared from GIS information covering a research site is converted to a three dimensional surface mesh that is composed by quad and full hexahedral space meshes. Around this surface mesh, an extended computational domain volume was designed. Atmospheric flow boundary conditions were used at inlet and roughness height and was considered at terrain by using rough wall function. Two different wind conditions that was relatively stable during certain periods were compared in 3 different locations for validating the accuracy of the CFD computed solution. The result shows about 10 % of difference between the calculated result and measured data. This procedure can simulate a prediction of time-series data for airborne virus spread that can be used to make a web-based forecasting system of airborne virus spread.

강구 Kang Ku , 홍성구 Hong Seong-gu , 지광재 Ji Kwang-jae , 최준열 Choi June-yeol , 이효혜미 Lee Hyo-hyemi , 김한중 Kim Han-joong , 박성직 Park Seong-jik

DOI: JKWST Vol.56(No.1) 89-99, 2014

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The cultivation of biomass crops is now global demand for decreasing emissions of carbon dioxide (CO2) from fossil fuel. Miscanthus species have been studied as a suitable crop for biomass production, due to its characteristics of fast growth and high biomass. In Korea, Miscanthus species have gained wide attention as an option for biomass production alternative to fossil fuels, recently. New strain of giant Miscanthus has been developed and two large trial sites for the giant Miscanthus production were built in the lower reaches of the Geum River. To evaluate the ecological influence of the giant Miscanthus as an bioenergy crop for the future, we investigated the impact of the construction of the giant Miscanthus production fields on the biota and also compared it with biota in paddy fields near the study sites. The biota including plants, amphibians, reptiles, mammals, avifauna, insects, and bugs was investigated. The plant diversity of the giant Miscanthus production fields was poorer than the paddy fields because the high height of the giant Miscanthus might hinder the growth of other plants. However, the giant Miscanthus production fields serves habitat to animals, leading to rich diversity of animals including avifauna, insects, and bugs. The rich diversity of the animals in the giant Miscanthus production fields coincides with the fact that the giant Miscanthus was grown without any pesticide, herbicide, and fertilizer. This study showed that the giant Miscanthus can influence on biota and further long term study is needed to elucidate the interaction between the diversity of biota and the giant Miscanthus.

김찬식 Kim Chan Sik , 임성훈 Eam Sung Hoon

DOI: JKWST Vol.56(No.1) 101-107, 2014

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It has been known that Terzaghi's consolidation theory is not well consistent with the consolidation phenomenon on the soft clay ground, but this theory has still been adopted normally in practice because there is no method for estimating the consolidation settlement and rate easier than Terzaghi's theory. It is impossible to map whole part of consolidation settlement vs time curve to the curve of Terzaghi'z average degree of consolidation. If the primary consolidation and the secondary compression are happened same time, it would be useless of trying to find the end of primary consolidation, but it is needed for using Terzaghi's theory that the end of consolidation is determined to the time of beginning consistency between the final settlement analyzed with curve fitting and the experimented consolidation settlement.