원철희 Won Chul-hee , 신민환 Shin Min-hwan , 최중대 Choi Joong-dae , 임경재 Lim Kyoung-jay , 신현준 Shin Hyun-jun

DOI: JKWST Vol.55(No.5) 1-7, 2013

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The objective of this research was to experimentally test the effect of tillage methods on the reduction of runoff, non-point source (NPS) pollution load, sediment and discharge under a rainfall simulation. We used the runoff plots of 5 m×30 m (L×W) in size. Experimental treatments were conventional tillage (CT), CT-rice straw bundle (CT-RSB) and two no-till (NT) plots; slope of 3 % or 8 %; and rainfall intensity of 30 mm/hr. The rainfall simulation was conducted to three times. The time to initial runoff from NT plots was less than that from CT plots regardless of the slope and it was delayed about 65～90 % compared to that of CT plot. And sediment discharge of 8 % slope reduced to 55 % compared to CT plot. But the sediment discharge was not occurred at 3 % slope. The NT and CT-RSB methods have a great possibility of reducing runoff and NPS pollution loads. Runoff rate of NT plots was significantly lower than those of CT plot. The average NPS pollution loads of the NT plots and CT-RSB plot reduced about 55～80 % and 2.1～40 % compared to those of the CT plots, respectively. It was also shown that runoff and NPS pollution loads reduction by NT method could be very significant and contribute to improve the water quality of streams in agricultural regions. It was concluded that the use of NT method on agricultural fields could reduce soil erosion and muddy runoff significantly and help improve the water quality and aquatic ecosystem.

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

DOI: JKWST Vol.55(No.5) 9-16, 2013

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This study finds the characteristics of long-term settlement of Bottom Ash and to review the application of Singh-Mitchell creep equation and Burgers Model to the creep behavior of Bottom Ash. In the undrained state, it was confirmed that creep behavior appeared in the range to 30-80 % of the maximum deviator stress by applying condition in other three stresses through triaxial compression test after isotropically consolidation. By using sieve analysis, it was compared to each sample that was passed through 9.5 mm, 2 mm, 0.25 mm sieves. Also, using Singh-Mitchell creep equation and Burgers Model, it was compared between the theoretical behavior and the observed behavior for each sample. In the result, it is found that creep behavior of Bottom Ash is similar to the theoretical behavior of Singh-Mitchell creep equation and Burgers Model in early stage and it is possible to predict creep behavior of Bottom Ash by these models.

강구 Kang Ku , 엄병환 Um Byung-hwan , 김영기 Kim Young-kee , 박성직 Park Seong-jik

DOI: JKWST Vol.55(No.5) 17-23, 2013

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Six-valent chromium (Cr^6＋) is a highly toxic pollutant, supplied in a variety of industrial activities such as leather tanning, cooling tower blowdown, and plating. Herein, we investigated the removal of Cr^6＋ from aqueous phase using low-cost adsorbents. Steel slag, montmorillonite, illite, kaolinite, red mud, and acid treated red mud with 0.5, 1.0, and 2.0 M HCl were used as adsorbent for the removal of Cr^6＋ and the results showed that acid treated red mud with 2.0 M HCl (ATRM-2.0 M) had higher adsorption capacity of Cr^6＋ than other adsorbents used. Accordingly, Cr^6＋ removal by ATRM-2.0 M were studied in a batch system with respect to changes in initial concentration of Cr^6＋, initial solution pH, adsorbent dose, adsorbent mixture, and seawater. Equilibrium sorption data were described well by Freundlich isotherm model. The influence of initial solution pH on Cr^6＋ adsorption was insignificant. The use of the ATRM-2.0 M alone was more effective than mixing it with other adsorbents including red mud, zeolite, oyster shell, lime stone, and montmorillonite for the removal of Cr^6＋. The Cr^6＋ removal of the ATRM-2.0 M was slightly less in seawater than deionized water, resulting from the presence of anions in seawater competing for the favorable adsorption site on the surface of ATRM-2.0 M. It was concluded that the ATRM-2.0 M can be used as a potential adsorbent for the removal of Cr^6＋ from the aqueous solutions.

권경석 Kwon Kyeong-seok , 이인복 Lee In-bok , 황현섭 Hwang Hyun-seob , 하태환 Ha Tae-hwan , 하정수 Ha Jung-soo , 박세준 Park Se-jun , 조예슬 Jo Ye-seul

DOI: JKWST Vol.55(No.5) 25-35, 2013

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In swine house, dust generation comes from various sources and is known to be harmful both for the animals and the farmers because the dust contains biological and gaseous matters. When farmers are constantly exposed to the dusts, they can suffer chronic or acute respiratory symptoms and have high probability of manifesting various diseases. To address this problem, understanding of the mechanism of dust generation is very important. In this paper, the dust concentration of inhalable, respirable, TSP and PM10 were monitored and analyzed according to the pig-activity level, ventilation quantity and feeding method in fattening pig house. From the measured results, in case of the concentration of TSP, an inverse-linear relation with ventilation rate (R²＝0.88) and linear relation with the installation height of feed supply pipe (R²＝0.73) were determined. However in case of the concentration of PM10, no particular relationship with the variables was observed. Using the concentration of inhalable and respirable dust based on the pig-activity level, multi-variate regression analysis was conducted and results have shown that the movement of pigs can contribute to the dust generation (p＜0.05, R²＝0.71, 0.61). The relationship determined between dust generation and environmental variables investigated in this study is very significant and useful in conducting dust-reduction researches.

정충길 Jung Chung Gil , 문장원 Moon Jang Won , 장철희 Jang Cheol Hee , 이동률 Lee Dong Ryul

DOI: JKWST Vol.55(No.5) 37-48, 2013

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The objective of this study is to assess the impact of potential climate change on the hydrological components, especially on the streamflow, evapotranspiration and snowmelt, by using the Soil Water Assessment Tool (SWAT) for 17 Hanriver middle watersheds of South Korea. For future assessment, the SWAT model was calibrated in multiple sites using 4 years (2006-2009) and validated by using 2 years (2010-2011) daily observed data. For the model validation, the Nash-Sutcliffe model efficiency (NSE) for streamflow were 0.30-0.75. By applying the future scenarios predicted five future time periods Baseline (1992-2011), 2040s (2021-2040), 2060s (2041-2060), 2080s (2061-2080) and 2100s (2081-2100) to SWAT model, the 17 middle watersheds hydrological components of evapotranspiration, streamflow and snowmelt were evaluated. For the future precipitation and temperature of RCP 4.5 scenario increased 41.7 mm (2100s), ＋3 ℃ conditions, the future streamflow showed ＋32.5 % (2040s), ＋24.8 % (2060s), ＋50.5 % (2080s) and ＋ 55.0 % (2100s). For the precipitation and temperature of RCP 8.5 scenario increased 63.9 mm (2100s), ＋5.8 ℃ conditions, the future streamflow showed ＋35.5 % (2040s), ＋68.9 % (2060s), ＋58.0 % (2080s) and ＋63.6 % (2100s). To determine the impact on snowmelt for Hanriver middle watersheds, snowmelt parameters of SWAT model were determined through evaluating observed streamflow data during snowmelt periods (November-April). The results showed that average SMR (snowmelt / runoff) of 17 Hanriver middle watersheds was 62.0 % (Baseline). The annual average SMR were 42.0 % (2040s), 39.8 % (2060s), 29.4 % (2080s) and 27.9 % (2100s) by applying RCP 4.5 scenario. Also, the annual average SMR by applying RCP 8.5 scenario were 40.1 % (2040s), 29.4 % (2060s), 18.3 % (2080s) and 12.7 % (2100s).

이현만 Hyunman Lee , 김태곤 Taegon Kim , 최원 Won Choi , 서교 Kyo Suh , 이정재 Jeongjae Lee

DOI: JKWST Vol.55(No.5) 49-58, 2013

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Appropriate random variables and probability density functions based on statistical analysis should be defined to execute reliability analysis. Most studies have focused on only normal distributions or assumed that the variables showing non-normal characteristics follow the normal distributions. In this study, the reliability problem with non-normal probability distribution was dealt with using the convolution method in the case that the integration domains of variables are limited to a finite range. The results were compared with the traditional method (linear transformation of normal distribution) and Monte Carlo simulation method to verify that the application was in good agreement with the characteristics of probability density functions with peak shapes. However it was observed that the reproducibility was slightly reduced down in the tail parts of density function.

윤용선 Yoon Yong-sun , 이재득 Lee Jae-deuk , 김용성 Kim Yong-seong

DOI: JKWST Vol.55(No.5) 59-69, 2013

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