• Proceedings of the Safety Management and Science Conference
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• 2001.11a
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• pp.193-202
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• 2001

The individual rotten water purification tank recently discharges wastewater and sewage through the outlet without purification ability. The outlet water and affiliated water purification tank with microorganism cultivator tank cultivates microorganism and then drops the value BOD, COD of sewage and discharges the quality of water into the outlet. The blower and water pump operating continuously prompts the waste of energy and deterioration of equipment. Each room of deposition tank, foaming tank, microorganism cultivator tank is equipment with the sludge detection senses so it can detect the density of each room. The power-drive plant of the blower and water pump which ate the system cultivating the microorganism must be made as fuzzy controlization (If the sludge amount of each room become higher, the rate of operation of blower and water pump must heighten, on the contrary, in case of row sludge amount, the total handling amount and microorganism handling amount of each room of control. Tank reducing the rate of operation must be DB. At present, the blower amount in proportion to the sludge and oxygen demanding amount has to control. Each mom must be checked outlet level of the outlet, also each room must flow backward discharge materials, and must operate feed-back control until we want to be come as a below value of BOD/COD(10PPM ; KS).

• Journal of the Korea Safety Management & Science
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• v.4 no.3
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• pp.177-187
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• 2002

The contamination problem is getting worse now a day because of the industrial activities. Recently it has been announced that there's environmental hormone in river and lake which produces clean water, also there's too many of algae reproduces under the water and some virus in the drinking water. The quality of water is very important. pure and clean water is not only a precondition for human being to live but a basic factor to improve the quality of life. so a water purification system must be developed. This study is about the surface washing treatment technique. We tried to use a rotary nozzle to get a tush degree of efficiency, for it was not enough with present way of washing. The nozzle is run by water pressure. The results of the experiment are as follows. We got a clean and equal surface after washing. After washing, the water's maximum consistency was 330NTU and it shows that this way is better than before one with 215NTU. Clean level of the filter was 6$^{\circ}$and it's 2.8 times higher than 17$^{\circ}$with the old way. We can see the results that the new way of washing is more effective than old way based on this study.

• Journal of the Korea Safety Management & Science
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• v.3 no.4
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• pp.53-63
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• 2001

The individual rotten water purification tank recently discharges wastewater and sewage through the outlet without purification ability. The outlet water and affiliated water purification tank with microorganism cultivator tank cultivates microorganism and then drops the value BOD, COD of sewage and discharges the quality of water into the outlet. The blower and water pump operating continuously prompts the waste of energy and deterioration of equipment. Each room of deposition tank, foaming tank, microorganism cultivator tank is equipment with the sludge detection senses so it can detect the density of each room. The power-drive plant of the blower and water pump which are the system cultivating the microorganism must be made as fuzzy controlization (If the sludge amount of each room become higher, the rate of operation of blower and water pump must heighten, on the contrary, in case of row sludge amount, the total handling amount and microorganism handling amount of each room of control. Tank reducing the rate of operation must be DB. At present, the blower amount in proportion to the sludge and oxyzen demanding amount has to control. Each room mus be checked outlet level of the outlet, also each room must flow backward discharge materials, and must operate feed-back control until we want to be come as a below value of BOD/COD(10PPM ; KS).

• Journal of Environmental Impact Assessment
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• v.14 no.1
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• pp.37-46
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• 2005

In this study, field surveys were performed for 12 stations in main stream of Hongjechun and 3 stations in 2 tributaries, respectively, in order to find out dried reaches of the stream, and to examine the water quality of the stream, and to suggest methods to improve the stream concerned into eco-stream. In the results of water quality in stream, however distinct difference for seasonal variation of the water quality was not found, the water quality of winter was relatively better than that of other seasons. Annual mean concentration of BOD was 6.5mg/L in the upper reach, 11.8mg/L in the middle reach, 15.3mg/L in the lower reach of main stream, and total mean was 12.5mg/L, while the BOD concentration was 3.6mg/L in the upper reach, and was 9.6mg/L in the low reach of Gukichun, the tributary. Based on flow examination, the level of water depth was so low and the flow can not be traveled downstream in the reach between ST-9 and ST-10 for low water season, whereas it was observed that the flow was traveling except the dry season even the water level was lower than that of adjacent stations.

• Journal of Bio-Environment Control
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• v.19 no.1
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• pp.12-18
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• 2010

Irrigation management methods controlled by integrated solar radiation (ISR) or drainage level sensor were evaluated in rockwool or coir bag culture as tomato (Solanum lycopersicum L.) production system. Substrate water content and drainage percentage were more stable in the drainage level sensor method than in the ISR method regardless of substrate type. Total yield and marketable yield were high in the drainage level sensor method, but not between substrates in the same irrigation management method. Sugar content was affected more by the substrate type than irrigation method. The drainage level sensor method was elucidated to be better than the ISR method regardless of substrate type.

• International Journal of Contents
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• v.14 no.3
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• pp.53-60
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• 2018

Based on the previous studies on sinkholes and ground subsidence conducted until date, the factors affecting the occurrence of sinkholes can be divided into natural environmental factors and human environmental factors in accordance with the purpose of the study. Furthermore, to be more specific, the human environment can be classified into the artificial type and the social type. In this study, the assessment indices for assessing risks of sinkholes and ground subsidence were developed by performing AHP analysis based on the results of the study by Lee et al. (2016), who selected the risk factors for the occurrence of sinkholes by performing Delphi analysis targeting relevant experts. Analysis showed that the artificial environmental factors were of significance in affecting the occurrence of sinkholes. Explicitly, the underground factors were found to be of importance in the natural environment, and among them, the level of underground water turned out to be an imperative influencing factor. In the artificial environment, the underground and subterranean structures exhibited similar importance, and in the underground structures, the excessive use of the underground space was found to be an important influencing factor. In the subterranean ones, the level of water leakage and the erosion of the water supply and sewage piping system were the influential factors, and in the surface, compaction failure was observed as an imperative factor. In the social environment, the regional development, and above all, the groundwater overuse were found to be important factors. In the managemental and institutional environment, the improper construction management proved to be the most important influencing factor.

• Journal of Wetlands Research
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• v.4 no.2
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• pp.57-66
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• 2002

The local storm occurred Nakdong river basin from August 4 to 11 of the year 2002, resulting in a record 500-600mm rainfall. The heavy rain continued for more than 10 days and especially between 3 to 4 am of August 9, 50mm per hour local storm occurred in Hanrim-myun area, Kimhae. 8 days after the storm, the water level of Nakdong river rose rapidly and the river flowed backward the branches. T he draining of the protected low wetland was unable and the water level of the inner bank area rose suddenly, causing the inundation in several areas. Baeksan bank of Nam river, Gahyun(Samhak) bank of Hwang river, and Kwangam bank of Shinban river, where the draining facilities were under construction or constructed recently, were failed by the piping around the draining culvert. This study analyze the cause of the damage in Nakdong river banks and suggests the countermeasures for future improvement. The damaged spot of the river bank was surveyed, and the rainfall and the fluctuation in the water levels were reviewed. Finally for the flood inundation prevention at the inner bank area, new floodplain management plan as the protect of low wetland established.

• Journal of environmental and Sanitary engineering
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• v.21 no.2 s.60
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• pp.36-46
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• 2006

The purpose if this study was to investigate mother' oral health management behavior to their children. Two hundreds sixty seven mothers with elementary school students were surveyed among the residents living of Iksan city, Korea. A questionnaire was constructed and administered to the samples. The research focused in the following items: the subjects' socio-demographic factors such as education level and employment and so on; their knowledge of plaque; the leading causes of caries, regular dental examinations; dental treatment; their interest in their children's dental health; the frequency of the subjects examining their children's teeth; non-cariogenic food preparation, etc. Being based in collected data, mothers' oral health management behavior to their children were analyzed according to maternal socio-demographic factor and result were following. There was a difference in the subjects knowledge of dental plaque in accordance with their employment or unemployment and family income. There was no difference in mother's oral health management behavior to their children according to parents' education level, the subjects' age and family income. Most of mother answered the main reason of dental caries was that their children did not toothbrush their teeth regularly and there was a difference in the understanding of the subjects in accordance with the education level of fathers and family income. The subjects had a low understanding of the effect of preventing caries with the help of fluoride. They didn't have enough understanding of water fluoridation. So it is necessary that active campaigns should be launched to enlighten people in relation to the ways of preventing dental caries with fluoride.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.4
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• pp.11-20
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• 2022

Currently, the operation rule of agricultural reservoirs in case of drought events follows the drought forecast warning standard of agricultural water supply. However, it is difficult to preemptively manage drought in individual reservoirs because drought forecasting standards are set according to average reservoir storage ratio such as 70%, 60%, 50%, and 40%. The equal standards based on average water level across the country could not reflect the actual drought situation in the region. In this study, we proposed the improvement of drought operation rule for agricultural reservoirs based on the percentile approach using past water level of each reservoir. The percentile approach is applied to monitor drought conditions and determine drought criteria in the U.S. Drought Monitoring (USDM). We applied the drought operation rule to reservoir storage rate in extreme 2017 spring drought year, the one of the most climatologically driest spring seasons over the 1961-2021 period of record. We counted frequency of each drought criteria which are existing and developed operation rules to compare drought operation rule determining the actual drought conditions during 2016-2017. As a result of comparing the current standard and the percentile standard with SPI6, the percentile standard showed severe-level when SPI6 showed severe drought condition, but the current standard fell short of the results. Results can be used to improve the drought operation criteria of drought events that better reflects the actual drought conditions in agricultural reservoirs.

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.871-879
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• 2022

An increasing global population requires a greater food supply, and accordingly there is demand for enhanced production of rice, as a major crop plant that covers half of the world's population. Rice production in arid area is extremely difficult due to poor soil fertility, salinity, deficit of irrigation water, and weather conditions. The aim of the present study was to determine whether various fertilization recipes could provide a countermeasure to allow rice production while also providing soil amendment such as soil pH adjustment. The study was conducted at an experimental field of the United Arab-Emirates (UAE) from January to April, 2022. Rice seedlings (cv. Asemi, alkaline-resistant) were transplanted in plastic containers, and different types of water and nutrient managements were employed as follows: water management (flooding and aerobic for NPKs treatment group) and nutrient management (NPKs, slow release fertilizers [SRFs] and SRFs + NPK-1 treatment groups with flooding). Water and nutrient management did not show any effect on soil pH adjustment. Rice growth was significantly enhanced in the flooding compared to the aerobic condition, whereas the effect of nutrient management clearly differed among the treatment groups, with SRFs + NPK-1 showing the best results followed by SRFs and NPKs. Most of the fertilization groups markedly accumulated soluble sugars in the shoots and grains of rice plants, but concomitantly a decrease in the roots. Overall, the level of starch showed a tendency of relatively slight perturbation by fertilization. Taken together, the results indicate that soil physical structure should be preferentially amended to find the key for suitable rice production.