• 한국수자원학회논문집
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• 제34권5호
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• pp.487-497
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• 2001

옥정호에 대한 수질변화 조사 자료를 토대로 수질모의를 실시하였으며, 그 결과 바탕으로 효율적인 댐저수지 수질관리 방안을 제시하였다. 옥정호의 수질은 계절에 다라 중영양상태와 부영양상태를 나타내는 것으로 평가되었으며 이러한 수질상태는 외부로부터 유입되는 오염원에 많은 영향을 받게 되므로 우선 유역으로부터 유입되는 오염부하의 정확한 산정이 필요한 것으로 평가되었다. 1999년에 조사한 7차례의 강우기간 중 총 부하와 일년간 발생한 총 부하를 비교하면 강우량은 17.5%인데 비해 SS는 72.8%, TN과 TP는 약 50%가 강우기에 유입되는 것으로 조상되었다. 또한 퇴적물의 용출율은 TP의 경우 가두리 양식장이 운영되던 지점에서는 11.92 mg/L, 정기수질 조사지점에서 0.2∼1.9 mg/L로 국내·외 자료와 비교하여 용출율이 작은 것으로 나타났다. 댐저수지 수질관리 방안 수립을 위하여 WASP5 모형을 적용하였으며 검증된 결과를 이용하여 각 소유역에서 오염부하 삭감에 따른 6가지 방안에 대한 수질모의를 실시하였고 각각에 대한 수질개선 효과를 제시하였다. 가장 효율적인 방안은 임실천 유역과 관촌교 유역의 오염부하를 제어하는 방안으로 평가되었으며, 가장 수질개선효과가 좋은 것은 대표 세유역의 오염부하를 제어하는 것으로 나타났다. 이를 바탕으로 수질개선을 위한 하·폐수처리장의 건설 적지를 제시하였다.

• 한국물환경학회지
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• 제37권3호
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• pp.175-189
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• 2021

In this study, 48 streams in the Sapgyo Watershed were selected, and the Load Duration Curves (LDC) were drawn up for each stream using water quality and flow monitoring over the last three years (2018-2020), and it was evaluated whether the target water quality was achieved for each flow section. As a result of evaluating whether or not the target water quality exceeded according to the LDC, it was found that 22 rivers exceeded the target water quality. Five rivers exceeded the target water quality due to point pollutant sources, 13 rivers exceeded the target water quality due to non-point pollutant sources, and 4 rivers exceeded the target water quality due to both point and non-point pollutant sources. Among the rivers that exceeded the target water quality due to point pollutant sources, which included domestic sewage of the untreated population, there is a need to reduce the influx of polluted loads by the untreated population. The use of eco-friendly fertilizers is recommended for rivers with a relatively high farmland ratio among rivers exceeding the target water quality due to non-point pollutant sources, and installation of boiling point reduction facilities that can reduce the amount of polluted load introduced during rainfall or manage water shores. In rivers with a large number of livestock breeding heads, the livestock houses located in these rivers need to be preferentially transferred to livestock manure treatment plants. Due to the high ratio of land area because of urbanization, initial rainwater treatment facilities are required to reduce the amount of pollutant load flowing into the river through the impermeable layer during rainfall.

• 한국수자원학회논문집
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• 제52권6호
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• pp.441-449
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• 2019

가뭄은 다른 자연재해에 비해 지속기간이 길고 규모가 광범위하여 사회 경제적인 피해가 크게 발생한다. 또한 공간적, 기술적, 경제적 및 사회적 특성에 따라 같은 규모의 가뭄이 발생하더라도 피해 규모는 지역별로 상이하게 발생한다. 본 연구에서는 가뭄에 대한 사회 경제적 영향인자를 고려하여 가뭄 취약성 평가를 실시하였다. 충청도 지역을 대상으로 가뭄과 관련된 기존 사례 분석을 통해 영향인자들을 파악하고 주성분 분석을 적용하여 최종 평가인자를 선정하였다. 선정된 인자들에 대한 가중치 산정을 위해서 엔트로피 기법을 적용하였다. 그 결과 충청도에서는 농가인구수, 기초생활수급자수, 상수도요금격차지표, 산업단지면적, 지하수이용량, 1인당가용수자원량, 상수도보급률, 물재정건전성, 생활용수이용량, 농업용수이용량 및 농경지면적이 평가인자로 선정되었으며, 이 중 농업관련 인자가 큰 가중치를 가지는 것으로 나타났다. 또한, 취약성 평가를 수행한 결과 청주시와 당진시 그리고 서산시가 가뭄에 가장 취약한 것으로 나타났다.

• 한국환경과학회지
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• 제21권3호
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• pp.289-296
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• 2012

The purpose of this study was to identify the irrigation intervals and the amount of suitable growing substrate needed to achieve the desired shallow-extensive green roof system during a dry summer in Korea. In terms of treatment, three types (SL, $P_6P_2L_2$, $P_4P_4L_2$) with varying soil mixture ratios and two types (15 cm, 25 cm) with varying soil depths were created. The results have been analyzed after measuring growth and soil water contents. The difference of growth by treatment was significant in terms of green coverage, height, leaf width and photosynthesis. In measurement of chlorophyll content, no difference was detected when measured against soil depth. According to the growth measurement of Zoysia japonica with respect to differing soil mixture ratios in the 15 cm-deep treatment, a statistical difference was detected at the 0.05 significance level in photosynthesis. In case of green coverage, height, chlorophyll content and leaf width, no statistical significance was observed. In case of the 25 cm-deep treatment, a statistical significance was observed in height and photosynthesis. In terms of green coverage, chlorophyll content and leaf width, no statistical significance was detected. In comparisons of soil moisture tension and soil water contents, the irrigation interval and amount were 8 days and 14.9 L in the SL (15 cm) treatment, respectively. The irrigation interval showed for 10 days a 1.3-fold increase, and the irrigation amount was 27.4 L 1.8-fold more than SL (25 cm), respectively. For $P_6P_2L_2$ (15 cm) treatment, the irrigation interval and amount were 12 days and 20.7 L, respectively. However, an irrigation interval under $P_6P_2L_2$ (25 cm) was for 15 days 1.3 times longer than $P_6P_2L_2$ (15 cm), and an irrigation amount of 40 L was 1.9 times more than that under $P_6P_2L_2$ (15 cm). In $P_4P_4L_2$ (15 cm) treatment, it was indicated that the irrigation interval was 15 days, and the irrigation amount was 19.2 L. It was not needed to irrigate for 16 days under $P_4P_4L_2$ (25 cm) treatment during the dry summer and the longest no-rain periods. The irrigation interval and amount under $P_4P_4L_2$ were 1.8-fold and 1.3-fold, respectively, more than SL treatment as affected by soil mixture ratio. Comparatively $P_4P_4L_2$ had more 1.3-fold and 0.9-fold in irrigation interval and amount more than $P_6P_2L_2$. Therefore, it can be noted that different soil depth and soil mixture ratios had a significant effect on the irrigation interval and amount.

• 수산해양기술연구
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• 제44권1호
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• pp.20-30
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• 2008

In order to evaluate the biodegradability of bait used in the pot for swimming crab, water tank experiments were conducted. Mackerel is the most commonly used natural form of bait to catch the swimming crabs, and therefore was used in this experiment for the biodegradability according to the manufacturing process of the bait. From the biodegradability test on chemical oxygen demand(COD), total nitrogen(T - N), total phosphorus(T - P), ammoniac nitrogen, nitrite nitrogen and nitrate nitrogen per unit weight of the bait based on the production rate and the accumulated amount of pollutants, it was concluded that the smaller the size of the mackerel pieces, the higher the production rate and accumulated amount of organic matter and nutrients which was unfavorable to water pollution. The amount of pollutants released from the intestine of the tuna was similar with that from the whole mackerel. For the operation period of 111 days, the accumulated concentrations of tested pollutants from the tuna which were 67.3 mgCOD/g d, 86.4 mgT N/g d, 3.1 mgT - P/g d, were almost half comparing with those from the mackerel which were 65.7 - 94.4 mgCOD/g d, 83.8 - 109.4 mgT - N/g d, 3.1 - 5.2 mgT - P/g d. The amount of pollutants released from the intestine of the tuna was slightly less than that from the mackerel that was cut into 8 pieces. but more than that from the mackerel which was not cut into pieces. Therefore, it can be concluded that the key factor in determining water pollution potential is not the kind of bait, but the processing or preparation method used.

• 한국구조물진단유지관리공학회 논문집
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• 제25권5호
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• pp.68-75
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• 2021

본 연구에서는 콘크리트의 균열조건에 따른 수분 흡수 현상을 해석적으로 분석하였다. 흡수 시간의 증가에 따라 콘크리트 표면을 통해 흡수되는 수분의 양을 실험적으로 분석한 기존 연구 결과들을 바탕으로 2차원 유한요소해석 모델을 개발하였다. 고려된 균열조건은 균열 폭(0.1 mm, 0.3 mm), 균열 깊이(0 ~ 250 mm), 균열 간격(0 ~ 200 mm)이며 총 30개 모델에 대한 유한요소해석을 수행하였다. 유한요소해석을 수행한 결과, 콘크리트 균열부의 수분 흡수량 증가에 중요한 영향을 미치는 조건은 균열 폭 및 균열 깊이의 변화로 확인되었다. 또한 비균열 조건의 콘크리트에 비해 균열부에서 추가로 흡수되는 물의 양을 정량적으로 분석하기 위하여, 균열부 수분 흡수계수(S_crack) 개념을 도입하고 이를 추정하기 위한 예측 식을 제안하였다. 균열 깊이에 대한 분석 결과, 콘크리트 균열 폭과 관계없이 균열 깊이 150 mm 이하에서는 균열로 인한 수분 흡수가 활발하게 발생할 수 있음을 확인하였다. 따라서 외부에 노출된 철근콘크리트 구조물은 제설제와 같은 수용액 등의 흡수로 인하여 철근 부식이 발생할 수 있음을 고려하면, 실제 시설물의 균열 조건을 파악하기 위해서는 시설물의 점검 및 진단 시에 기존 균열 폭에 대한 조사뿐만 아니라 균열 깊이에 대한 조사도 함께 수행되어야 할 것으로 판단된다.

• Restorative Dentistry and Endodontics
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• 제21권1호
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• pp.218-226
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• 1996

This study was performed to evaluate the possibility of pulpal damage by measuring temperature change occured in dentin according to the thickness of dentin, the time of irradiation and the output of laser energy when the dentin surfaces were irradiated with Nd-YAG laser under water coolant and no water coolant. Sound upper and lower molar teeth were sectioned with 1mm, 1.5mm and 2mm thickness of dentin discs and divided into 4 groups by dentin thiness. 0.5 watt, 1 watt, 1.5 watt and 2 watt-energied beam of pulsed 10 p.p.s of Nd : YAG laser was applied respectively to dentin surfaces for 8 secs and 16 secs when water coolant is used or not.Ant then the temperature changes occurd in dentin were measured at opposite surfaces of laser-irradiated dentin surfaces with digital thermometer. The results were as follow. 1. When the amount of irradiated energy was same, the temperatue changes of dentin were higher as the thickness of dentin discs was thinner(p<0.01). 2. When the amount of irradiated energy and the thickness of dentins were same, The temperature changes of dentin were lower under water coolant than under no water coolant in all groups(p<0.01). 3. With the increase of time of irradiation, the temperature changes of Dentin became higher in all groups and were steeply increased at initial period of irradiation of laser. 4. Under the same thickness of dentin, the temperature changes of dentin became higher as irradiated energy was increased. These results suggest that when the beam of Nd : YAG Laser is irradiated to dential hard tissue, amount of irradiating energy, thickness of dentin, using water coolant must be considered in order to minimize thermal damage of the pulp.

• 한국농공학회지
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• 제29권3호
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• pp.125-137
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• 1987

The purpose of this paper is to examine some difficulties in water management of agricultural reservoirs in Korea, for there are approximately more than 15,000 reservoirs which are now being utilized for the purpose of irrigation, along with the much amount of expenses and labors to be invested against droughts and floods periodically occurred. Recently, the effective use of water resources in the agricultural reservoirs with a single purpose, is becomming multiple according to the alterable environment of water use. Therefore, the task to allocate agricultural water rationally and economically must be solved for the multiple use of agricultural reservoirs. On the basis of the above statement, this study aims at suggesting the rational method of water management by introducing an optimal technique to allocate the water in an existing agricultural reservoir rationally, for the sake of maximizing the economic effect. To achieve this objective, a reservoir, called "0-Bongje" as a sample of the case study, is selected for an agricultural water development proiect of medium scale. As a model for the optimum allocation of water in the multi-purpose use of reservoirs a linear programming model is developed and analyzed. As a result, findings of the study are as follows : First, a linear programing model is developed for the optimum allocation of water in the multi-purpose use of agricultural reservoirs. By adopting the model in the case of reservoir called "O-Bongje," the optimum solution for such various objects as irrigation area, the amount of domestic water supply, the size of power generation, and the size of reservoir storage, etc., can be obtained. Second, by comparing the net benefits in each object under the changing condition of inflow into the reservoir, the factors which can most affect the yearly total net benefit can be drawn, and they are in the order of the amount of domestic water supply, irrigation area, and power generation. Third, the sensitivity analysis for the decision variable of irrigation which may have a first priority among the objects indicate that the effective method of water management can be rapidly suggested in accordance with a condition under the decreasing area of irrigation. Fourth, in the case of decision making on the water allocation policy in an existing multi-purpose reservoir, the rapid comparison of numerous alternatives can be possible by adopting the linear programming model. Besides, as the resources can be analyed in connection with various activities, it can be concluded that the linear programing model developed in this study is more quantitative than the traditional methods of analysis. Fifth, all the possible constraint equations, in using a linear programming model for adopting a water allocation problem in the agricultural reservoirs, are presented, and the method of analysis is also suggested in this study. Finally, as the linear programming model in this study is found comprehensive, the model can be adopted in any different kind of conditions of agricultural reservoirs for the purpose of analyzing optimum water allocation, if the economic and technical coefficients are known, and the decision variable is changed in accordance with the changing condition of irrigation area.

• 한국농공학회논문집
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• 제63권3호
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• pp.1-12
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• 2021

Optimal water management is to efficiently and equally supply an appropriate amount of water by using irrigation facilities. Therefore, it is necessary to evaluate water supply capacity through distribution simulation between the designed distribution rate and re-distributed rate according to the changed farming conditions. In this study, we recalculated the agricultural water supply amount of Geumcheon main canal, which beneficiary area was reduced due to the development of Gwangju-Jeonnam innovation city, and we constructed a canal network using the SWMM model to simulate the change in supply rate of each main canal according to the re-distributed rate. Even though the supply amount of the Geumcheon main canal was reduced from 1.20 m³/s to 0.90 m³/s, it showed a similar supply rate to the current, and the reduced quantity could be supplied to the rest of the main canal. As a result, the arrival time at the ends of all main canal, except for the Geumcheon main canal, decreased from 1 to 3 hours, and the supply rate increased from 4 to 17.0% at the main canal located at the end of the beneficiary area of Naju reservoir.

• 한국약용작물학회지
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• 제23권4호
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• pp.292-297
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• 2015

This study was carried out to have the basic and applied informations relating to develop the cultivation methods and to increase the productivity and quality of ginseng. 1 to 6 year old ginsengs of Jakyung cultivar were cultivated and the content and synthetic amount of carbohydrates were investigated with different plant tissues, growth stages, and years old. The concentration of total carbohydrates at six year old ginseng including water soluble and water insoluble carbohydrates was about 18.9%, 42.9%, and 43,6% in leaves, tap roots, and lateral roots, respectively. Water soluble carbohydrate of tap and lateral roots was slightly decreased from August until September, and then increased on November, whereas its water insoluble carbohydrate was increased from August to September and then decreased on November. Comparing with the content of carbohydrates of 1 to 6 year old ginsengs, it was continuously increased from one year old ginseng until five year old ginseng, however it was not increased much in six year old ginseng. The highest content of carbohydrates was at five year-old in all tissues of ginseng. Water soluble and water insoluble carbohydrates were significantly shown different in leaves, stems, tap roots, and lateral root at different growth stages and with different years old. The content of water soluble carbohydrate in the leaves was remarkedly higher compared to that of water insoluble carbohydrate, while in the root the content of water insoluble carbohydrate was clearly higher compared to the water soluble carbohydrate. Comparing with the synthetic amount of carbohydrates, water soluble carbohydrates was higher in the shoot than that in the root, whereas water-insoluble carbohydrates higher in the root than that in the shoot. Carbohydrates which would be utilized in ginseng tissues for short and long-term periods as major energy were appeared differently in between shoot and root, with different growth stages, and years old.