• Journal of Food Hygiene and Safety
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• v.14 no.3
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• pp.249-254
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• 1999

The present study was performed to investigate biodegradation rate of BPMC(2-sec-butylphenyl methyl carbamate) and chlorothalonil. In the biodegradation test of two pesticides by the modified river die-away method from June 17 to August 22, 1998, the biodegradation rate constants and half-life were determined in Nakdong(A) and Kumho River(B). Bio- degradation rate of BPMC was 27% in A sampling point, 40% in B sampling point after 7 days. Biodegradation rate constants and half-life of BPMC were 0.0460 and 15.1 days in A sampling point, 0.0749 and 9.3 days in B sampling point, respectively. Biodegradation rate of chlorothalonil was 100% in A and B sampling points after 7 days. Biodegradation rate constants and half-life of chlorothalonil were 0.1416 and 4.9 hours in A sampling point, 0.1803 and 3.8 hours in B sampling point, respectively. Biodegradation rate of chlorothalonil was faster than that of BPMC. Correlation analysis between biodegradation rate constants of pesticides and water quality(DO, BOD, SS, ABS, $NH_3-N\;and\;NO_3-N$) showed significant correlation with BOD, SS and $NH_3-N$. Furthermore, regression analysis with BOD, SS and $NH_3-N$ as independent variable and biodegradation rate constant as independent variable showed a significant linear equation. These results suggested that BPMC and chlorothalonil were mainly degraded by biodegradation, and the difference in biodegradation of two pesticides was due to difference of water quality.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.5
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• pp.371-381
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• 1997

Precipitation sampls were collected in Chonju-city during October 1994 to September 1995 and were analysed for major ions (N $a^{+}$, $K^{+}$, $Ca^{2+}$, $Mg^{2+}$, C $l^{[-10]}$ , NO/$_3$, S $O_4$$^{2-}$) and trace metals (Al, Cd, Ni, Pb, Sr, Zn) in addition to pH, in order to understand the chemical characteristics of acid rain and to estimate the origin of the determined ions. Most rain showed a neutral or alkaline character, and only 35% had a pH lower than 5.6. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ are identified as the primary contributors to precipitation acidity in this region. Neutralization of precipitation acidity occurs as a result of the dissolution of alkaline compounds containing $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ precipitation concentrations exhibit a seasonal pattern in which higher concentrations are observed during spring months and lower concentrations during summer months. However, the seasonal behavior of $H^{+}$ concentrations differs from this pattern, in that the highest concentrations occur during autumn months, owing to the different influence of neutralization processes. In all rain, S $O_4$$^{2-}$ concentration exceeded NO/$_3$$^{[-10]}$ concentration. The contribution of maritime sources to the total S $O_4$$^{2-}$ concentration was very low or negligible. For rain strongly affacted by yellow sand, $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$ ions show a sharp increase in concentration, reflecting the increased amount of dust and soil suspended in atmosphere. At the same time, S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ concentrations are at their highest levels while $H^{+}$ values are not comparably elevated, presumably beacause much of the acidity has been neutralized by alkaline substances. The seasonal variance of trace metal concentrations in rainwater is similar to that of major cations. The annual wet flux of acidic pollutants and trace metals wat calculated to be as follows: N $O_3$$^{[-10]}$ ; 2.32 g/$m^2$, S $O_4$$^{2-}$, 5.34 g/$m^2$, Al; 6.30 mg/$m^2$, Cd; 0.62 mg/$m^2$, Ni; 4.08 mg/$m^2$, Pb: 9.76 mg/$m^2$, Sr; 5.94 mg/$m^2$, Zn; 111 mg/$m^2$./$m^2$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.150-156
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• 2017

This study examined the stress recovery length due to the local damage of a 7-wire strand, which is applied widely to PSC (Post Tensioned Concrete) bridges and cable-stayed bridges. The 7-wire strand is a multiple stranded steel of PC prestressing strand. Owing to the nature of the material, it is damaged continuously after completion with corrosion being the main cause of damage. On the other hand, due to its structural characteristics, it is difficult to grasp the degree of damage inside the cable and the pattern of stress variation. In the case of cables applied to bridges, the parts that are susceptible to corrosion are generated depending on the water supply and installation shape, which may cause local damage. This study analyzed the tendency of performance degradation and stress recovery length according to local damage of a 7-wire strand, which is applied mainly to bridge post-tensioning or stay cables. This study developed a computer-based simulation model that was validated with experimental results. The model developed in this study can be used to evaluate the safety level and estimate the remaining life span of P SC bridges or cable-stayed bridges.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.438-443
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• 2007

This study was done to investigate perchlorate contamination in Nakdong river. The perchlorate was detected in Nakdong river and ranged from ND to $82.1{\mu}g/L$. The highest concentration was observed in Wheguan. The perchlorate concentration was decreased with the down stream of Nakdong river. Three different virgin activated carbons made of each coal(Calgon), coconut(Samchully) and wood(Picabiol) based activated carbon(AC) were tested for an adsorption performance of perchlorate in a continuous adsorption column. Breakthrough behavior was investigated that the breakthrough points of coal, coconut and wood based AC as 2,300 bed volumn(BV), 719 BV and 288 BV respectively. Adsorption capacity(X/M) of real, coconut and wood based AC was observed. The experimental results of adsorption capacity showed that coal based AC was highest$(768.2{\mu}g/g)$, coconut based AC was intermediate$(299{\mu}g/g)$ and wood based AC was lowest$(99.2{\mu}g/g)$. Moreover, carbon usage rates(CURs) for coal, coconut and wood based AC had been shown as 0.71 g/day, 2.16 g/day and 3.45 g/day respectively. The constant characteristic of the system, k of coal, coconut and wood based ACs were found to be 307.2, 102.5 and 94.2, respectively.

• Journal of Soil and Groundwater Environment
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• v.8 no.2
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• pp.9-18
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• 2003

Sampling of waters from each stage of treatment system (Successive Alkalinity Producing System; SAPS), tailings seepage, and spring near the Hanchang coal mine of Kangwon Province were carried out seasonally and analyzed to evaluate the source and possible path of groundwater contamination by acid mine drainage (AM). Sulfur isotope compositions were measured to identify the origin of groundwater contaminations and the sulfate reduction processes in the SAPS. Low pH and high metal concentration of spring water indicates possibility of the groundwater contamination by AMD. Removal efficiency of acidity of the SAPS was 18.17 g/$\textrm{m}^2$/day on an average and the metal removal efficiency was almost 100%, which was higher than those of other treatment systems. However, no appreciable decrease of sulfur content and almost similar sulfur isotope compositions of water from each stage of the treatment system may suggest incomplete or very poor sulfate reduction by sulfate reducing bacteria. Chemical and sulfur isotope compositions showed that spring water was contaminated by seepage from mine tailings. And seepage of stonewall, a part of treatment system was affected by both tailings seepage and mine adit drainage. In this study site, the treatment system was constructed for the only AMD from mine adit not for tailings seepages, which resulted in the groundwater contamination from tailing seepages. Similar situation is expected in other abandoned coal mine areas.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.987-992
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• 2007

충청북도 내의 농업용 저수지중 26개소를 선정하여 관개초기, 홍수기 및 비관개기의 연 3회에 걸쳐 저수율을 파악하고 채수를 실시하였다. 또한, 현장(수온, pH, DO, EC)과 실내 수질분석(Cd, As, Cn, Hg, 유기인, Pb, $Cr^{+6}$ PCB, ABS, COD, SS, TP, TN)을 실시하여 저수지의 오염도를 평가하였다. 저수율 측정결과, 홍수기(97%)가 관개초기(72%)나 비관개기(66%)보다 높게 나타났다. pH 값의 측정결과, 수질기준$(6.0{\sim}8.5)$을 만족하고 있는 저수지의 비율은 35%(9개소)의 낮은 값을 보였다. EC와 DO 및 SS농도의 측정결과, 거의 모든 저수지에서 수질기준을 만족하고 있었으며, COD, TN, TP농도 측정결과, 수질기준 만족도는 관개초기 100%, 홍수기 81%, 비관개기 65%로 나타나, 저수량이 많은 관개초기보다 저수량이 적은 비관개기에 질소와 인의 관리가 필요한 것으로 판단된다. 또한, 사람의 건강항목(CN, Hg, 유기인, PCB, Cd, 비소As, Pb, $Cr^{6+}$, ABS)은 모든 저수지에서 관개 초기, 홍수기 및 비관개기에 모두 수질기준을 만족하였다. 점오염원을 관리하기 위해서는 저수지 상류유역에 있는 마을하수도를 정비하고, 축산분뇨처리시설 등을 설치하여 저수지로의 유입부하량을 저감할 필요가 있다. 또한, 비점원오염을 관리하기 위한 대책으로서, 질소농도를 저감시키기 위해서는 용존성 성분을 제공하는 비료의 시용량을 줄여야하며, TP농도를 저감시키기 위해서는 강우시 입자성 인의 유출을 제어할 필요가 있으며, 이를 위해서는 비가 많이 오는 여름철에 나지(裸地)나 밭에 식생이나 멀칭(mulching) 등으로 토양침식을 방지할 필요가 있다.가용한 장 단기간의 관측자료와 물수지 분석 연산식의 추정치를 바탕으로 관측자료에 의한 물수지 분석을 수행하였다. 분석 결과로 산지 소하천 유역인 설마천 시험유역의 각 수문요소의 물이동간의 정량적인 값을 알 수가 있었으며, 앞으로 추가적이고 지속적인 수문모니터링이 운영되고 물순환 해석 모형에 의한 검증이 수행된다면 정량적인 물순환 관계를 규명할 수 있을 뿐만 아니라 이와 관련된 수문요소기술을 확보할 수 있을 것이다.절한 타협과 조정을 필요로 한다. 그러나 절제의 한계를 넘어선다고 생각되거나, 조정의 노력이 불가능하거나, 실패했을 때 폭력적인 행동으로 나타나게 된다. 리차즈(I.A Richards)는 분노와 공포는 일단 겉잡을 수 없는 경향이 있다고 하면서 오늘날 폭력에 대한 요구가 일상의 정서 생활에 있어, 억압을 통한, 빈곤함을 반영하고 있지 않은지 생각해봐야 할 것이라고 충고한다. 조성 가이드라인(안)을 제시하였다.EX>$\ulcorner$세종실록$\lrcorner$(世宗實錄) $\ulcorner$지리지$\lrcorner$(地理志)와의 비교를 해보면 상 중 하품의 통합 9개소가 삭제되어 있고, $\ulcorner$동국여지승람$\lrcorner$(東國與地勝覽) 에서는 자기소와 도기소의 위치가 완전히 삭제되어 있다. 이러한 현상은 첫째, 15세기 중엽 경제적 태평과 함께 백자의 수요 생산이 증가하자 군신의 변별(辨別)과 사치를 이유로 강력하게 규제하여 백자의 확대와 발전에 걸림돌이 되었다. 둘째, 동기(銅器)의 대체품으로 자기를 만들어 충당해야할 강제성 당위성 상실로 인한 자기수요 감소를 초래하였을 것으로 사료된다. 셋째, 경기도 광주에서 백자관요가 운영되었으므로 지방인 상주지역에도 더 이

• Economic and Environmental Geology
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• v.43 no.1
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• pp.21-31
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• 2010

Mine and leachate waters were collected from the Okdong mine for study on reaction with oxidizing agents such as NaOCl and $H_2O_2$. The pH and EC of the mine and leachate waters are 5.77, 831 uS/cm, and 6.38, 1920 uS/cm, respectively. The concentrations of Mg, Mn, and Zn are 23.25 mg/l, 14.90 mg/l, and 22.99 mg/l for the mine water and 98.75 mg/l, 3.38 mg/l, and 6.16 mg/l for the leachate water. The concentrations of Mg, Mn and Zn decreased after the reaction with the oxidizing agents and mine water. The concentrations of Mg, Mn and Zn rapidly decreased when oxidizing agents increased. The saturation indices that were computed by visual MINTEQ for initial mine and leachate water were undersaturated with Mg, Zn and Mn compounds. The precipitates after the reaction with the oxidizing agents are composed mainly of mangano-calcite[(Mn, Ca)$CO_3$] with small amount of calcite-magnesian and calcite.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.1 s.28
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• pp.1-7
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• 2007

In order to develop the deep ocean water, the characteristics of vertical distribution of dissolved trace metals(Cd, Co, Cu, Ni, Pb, Zn) were investigated from Apr. to Oct., 2005 in the East Sea. Total six sampling sites were selected in Gangwon-Do and Gyeongsangbuk-Do. Accuracy of the analytical procedures was assessed by the SRM(CASS-4) for dissolved metals in seawater. The mean recoveries cf CASS-4 ranged from 89.4% for Co to 99.8% for Cd. In this study, the dissolved metal concentrations varied with space, time and element. The metal concentrations showed wide range in the surface. Cd, Ni and Zn showed a nutrient-type profile with surface depletion and enrichment at depths. However, Co, Cu and Pb were irregular in the vertical distribution. All metal concentrations studied in this study are lower than the criteria cf Korean drinking water.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.45-57
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• 2002

In this paper, the results gained by applying many impingement models to the cylinder and flat plate were analyzed in comparison with the experimental data to study a spray/wall interaction phenomena. To begin with, the behavior of spray injected normal to the wall was analysed using three different impingement models ; Naber and Reitz model(NR model), Watkins and Wang model(WW model) and Park and Watkins model(PW model) in the present calculation. The results obtained from these models were compared with experimental data of Katsura et. al. The results indicated that PW model was in better agreement with experimental data than the NR and WW model. Also f3r spray injected at 30DEG , the result of three models were compared with experimental data of Fujimoto et. al. The results showed that m model overpredicted the penetration in the radial direction because this model was based on the inviscid jet analogy. WW model did not predicted the radius and height of the wall spray effectively. It might be thought that this discrepancy was due to the lack of consideration of spray film velocity occurred at impingement site. The result of PW model agrees with the experimental data as time goes on. In particular, a height of the spray droplets was predicted more closely to the experimental data than the other two models. The results of PW model in which the spray droplets were distributed densely around the edge of droplet distribution shaped in a circle had an agreement with the experimental data of Fujimoto et. al. Therefore, it was concluded that PW model performed better than M and WW model for prediction of spray behavior. The numerical calculation using PW model performed to the cylinder similar to the real shape of DI engine. The results showed that vortex strength near the wall in the cylinder was stronger than that in the case of flat plate. Contrary to the flat plat, an existence of the side wall in the cylinder caused the tangential velocity component to be reduced and the normal velocity component to be increased. The flow tends to rotate to the inside of cylinder going upward to the right side wall of cylinder gradually as time passes. Also, the results showed that as the spray angle increases, the gas velocity distribution and the tumble flow seemed to be formed widely.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.4
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• pp.563-568
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• 2007

This paper presents a methodology for predicting nonlinear time series based on the neural network with weighted fuzzy membership functions (NEWFM). The degree of classification intensity is obtained by bounded sum of weighted fuzzy membership functions extracted by NEWFM, then weighted average defuzzification is used for predicting nonlinear time series. The experimental results demonstrate that NEWFM has the classification capability of 92.22% against the target class of GDP. The time series created by NEWFM model has a relatively close approximation to the GDP which is a typical business cycle indicator, and has been proved to be a useful indicator which has the turning point forecasting capability of average 12 months in the peak point and average 6 months in the trough point during 5th to 8th cyclical period. In addition, NEWFM measures the efficiency of the economic indexes by the feature selection and enables the users to forecast with reduced numbers of 7 among 10 leading indexes while improving the classification rate from 90% to 92.22%.