• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.14-21
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• 1998

In 1996, a cold-water damage occured in the paddy field at downstream of the Unmoon dam. To study the cause and the preventive measures of the cold-water damage a field study was performed during the growing season of 1997. Field measurements such as water temperatures at reservoir, irrigation canal and in the paddy field were made. As a result, there was no cold-water damage due to the right irrigation water management practice in 1997. The cold-water damage is passible to happen, however, and the preventive measures were provided.

• Current Research on Agriculture and Life Sciences
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• v.15
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• pp.39-46
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• 1997

In 1996, a cold-water damage occured in the paddy field at the downstream of the Umoon dam. To study the cause and the preventive measures of the cold-water damage a field study was performed during the growing season of 1997. Field measurements such as water temperatures at reservoir, irrigation canal and in the paddy field were made. As a result, there was no cold-water damage due to the right irrigation water management practice in 1997. The cold-water damage is possible to happen, however, and the preventive measures were provided.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.1
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• pp.52-59
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• 1999

Paddy rice is semi-tropical crop and requires warmirrigation water. If mean water temperature at the water source during the growing period is below 18$^{\circ}C$, sime kinds of water warming mechanism should be taken. In this study irrigation water temperature is measured and preventive measures to cold water damage on paddy rice are suggested. Field observations were performed at 100ha field area downtream of the Unmoon reservoir during the growing season of 1997. Land use, canal system, water temperature at irrigation canals. reservoir, and paddy fields were observed. In addition, growth and yield of the rice at selected plots were observed. Accordingly to the record, cold water damage occurred in this area due to the cold irrigation water supply in 1996. It did not occur because of the effective irrigation water management practice in 1997. However, several preventive measures such as pontoon intake system, using existing weir and construting a new warming pond, are suggested to prevent cold water damage in the future. If a new warming pond is construted to raise irrigation water temperature by 2 $^{\circ}C$, a pond area of 2.94 ha is required.

• Structural Engineering and Mechanics
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• v.86 no.6
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• pp.779-791
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• 2023

Long-termly used in water supply, an underground concrete pipe is easily subjected to the coupled action of pressure loading and flowing water, which can cause the chemo-mechanical damage of the pipe, resulting in its premature failure and lifetime reduction. Based on the leaching characteristics and damage mechanism of concrete pipe, this paper proposes a coupled chemo-mechanical damage and failure model of underground concrete pipe for water supply, including a calcium leaching model, mechanical damage equation and a failure criterion. By using the model, a numerical simulation is performed to analyze the failure process of underground concrete pipe, such as the time-varying calcium concentration in concrete, the thickness variation of pipe wall, the evolution of chemo-mechanical damage, the distribution of concrete stress on the pipe and the lifetime of the pipe. Results show that, the failure of the pipe is a coupled chemo-mechanical damage process companied with calcium leaching. During its damage and failure, the concentrations of calcium phase in concrete decrease obviously with the time, and it can cause an increase in the chemo-mechanical damage of the pipe, while the leaching and abrasion induced by flowing water can lead to the boundary movement and wall thickness reduction of the pipe, and it results in the stress redistribution on the pipe section, a premature failure and lifetime reduction of the pipe.

• The Journal of Korean Medicine
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• v.29 no.1
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• pp.117-133
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• 2008

Objectives : Since ancient times, Koreans have applied medicinal spabaths for treatment of various diseases. The objective of this study was to investigate the effect of strontium, one of the common ingredients of such baths, experimentally on acute skin barrier damage. Materials and Methods : Male hairless mice, average weight 20g, were divided into six groups. Each group consisted of five mice. The first was the normal, non-treated group. The second was the control group with acute skin barrier damage intentionally induced by TS. The third was the Ba-Sr1 group bathed in 1mg/L strontium chloride before and after inducing acute skin barrier damage by TS. The fourth was the Ba-Sr7 group bathed in 7mg/L strontium chloride before and after inducing acute skin barrier damage by TS. The fifth was the Sr1 group bathed in 1mg/L of strontium chloride only after intentionally inducing acute skin barrier damage by TS. The sixth was the Sr7 group bathed in 7mg/L of strontium chloride only after intentionally inducing acute skin barrier damage by TS. External changes of skin, skin erythema level, transepidermal water loss level, and GOT and GPT level of each group were checked immediately before and after TS, 3 hrs, 5 hrs and 24 hrs after inducing acute skin barrier damage. Then, tissue samples were made and examined for damage to epithelial cells, stratum corneum, change of mucous polysaccharide in dermis and amount of mast cells. Statistical analysis was performed by one way-ANOVA, Scheffe and Duncan for a post hoc test and pairwise comparison for comparing for difference between each time. Statistical significance was achieved if the probability was less than 5% (p<0.05) Results : 1. From skin erythema and TEWL level indicating the function of the skin barrier, we can know that it is helpful to the skin barrier to bathe in a water solution including a low concentration of strontium. 2. In the control group with acute skin barrier damage induced by TS, skin barrier damage persisted until 3-5 hrs and recovered after 5-24 hrs. Differently from the control group, in the case of taking a bath in a water solution including strontium, skin barrier damage recovered after only 3-5 hrs. Therefore, the bath with a water solution including strontium can promote recovery of the skin barrier. 3. Bathing in water solution including a higher concentration of strontium was more beneficial to recovery of skin barrier damage. 4. There was no influence on serum GOT and GPT from bathing in a water solution including strontium. Conclusions : The strontium was effective for recovery and mitigation of acute skin barrier damage induced by tape stripping. I suggest that strontium (Sr) can be used as an external treatment medicine, addedinto bath water to treat acute skin barrier damage.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.5
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• pp.583-598
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• 2009

From the engineering standpoint, this study puts a special emphasis on application of adaptive management. To do this, we analyze the recent issue about water scarcity of the Gwangdong dam. Using the system dynamics model, we defined the system including water balance in the dam, dam manager's operation rules, regional water supply and local water distribution, and customer damage. It was expected that the model is useful to explain the real case, and also water scarcity of Gwangdong led to total damage of about 2.56 billion won, mainly to customers in the Taebaeck city. Two adaptive management options (i.e., optimal allocation of limited water resources, and early control of dam storage) were applied to the model in order to examine whether adaptive management is effective to mitigate the damage, it is concluded that the case study could largely reduce or entirely avoid the damage with adaptive engineering options.

• Structural Engineering and Mechanics
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• v.67 no.6
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• pp.587-601
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• 2018

Elevated water tanks are inverted pendulum type structures where drift limit is an important criterion for seismic design and performance evaluation. Explicit drift criteria for elevated water tanks are not available in the literature. In this study, probabilistic approach is used to determine maximum drift limit for damage state of yielding and damage state of collapse for the elevated water tanks supported on RC frame staging. The two damage states are defined using results of incremental dynamic analysis wherein a total of 2160 nonlinear time history analyses are performed using twelve artificial spectrum compatible ground motions. Analytical fragility curves are developed using two-parameter lognormal distribution. The maximum allowable drifts corresponding to yield and collapse level requirements are estimated for different tank capacities. Finally, a single fragility curve is developed which provides maximum drift values for the different probability of damage. Further, for rational consideration of the uncertainties in design, three confidence levels are selected and corresponding drift limits for damage states of yielding and collapse are proposed. These values of maximum drift can be used in performance-based seismic design for a particular damage state depending on the level of confidence.

• Journal of the Korean institute of surface engineering
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• v.50 no.4
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• pp.259-265
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• 2017

5000 series aluminium alloys and austenitic stainless steels have excellent corrosion resistance and sufficient strength, which are widely used as materials for marine equipment and their parts in the marine environment. The corrosion characteristics of materials are important factors for selecting the appropriate material due to fluid component changes in the estuarine and coastal areas where seawater and fresh water are mixed. Therefore, for 5083 Al alloy, STS304 and STS316L widely used in the marine environment, anodic polarization experiments were performed to compare the corrosion damage characteristics of each material by three kinds of solutions of 100 % tap water, 50 % tap water+50 % natural seawater and 100 % natural seawater. As a result of the anodic polarization experiments, aluminum alloy (5083) caused locally corrosion on the surface in the tap water, and corrosion damage occurred all over the surface when the seawater was included. Stainless steels (STS304 and STS316L) presented almost no corrosion damage in tap water, but they grew pitting corrosion damage with increasing seawater concentration. STS316L showed better corrosion resistance than STS304.

• Journal of Nutrition and Health
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• v.43 no.6
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• pp.570-577
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• 2010

Water gets magnetically charged when it is contacted with a magnet. Although magnetic water products have been promoted since the 1930's, they have received very little recognition due to questionable effectiveness. Diethylnitrosamine (DEN) is a widely occurring nitrosamine that is one of the most important environmental carcinogens primarily inducing tumors of liver. In this study, the effect of magnetized water supplementation on lymphocyte DNA damage in ICR mice treated with DEN was evaluated using the Comet assay. Mice were divided into 3 groups: control, DEN, and DEN + magnetized water group. Fifteen mice were maintained in each group for the entire experimental period of 6, 12 and 18 weeks. Five mice in each group were sacrificed at 6, 12, and 18th weeks, followed by the Comet assay using the blood obtained from heart puncture of the mice. The level of lymphocyte DNA damage reflected by tail moment and other DNA damage indices of tail DNA (%) or tail length of the magnetized water group were significantly decreased after the 6th, 12th and 18th weeks of supplementation compared with the positive control, the DEN group. The relative DNA damage of the magnetized water groups compared to the DEN control group after 6th, 12th, and 18th weeks of supplementation were 42.2%, 40.8%, and 32.9% for DNA in tail, 31.2%, 32.6%, and 21.3% for tail length, and 33.8%, 33.8%, and 24.6% for tail moment, respectively. This is the first report demonstrating that magnetized water may be involved in the lowering effect of the DNA damage in DEN-treated ICR mice. This result suggests that the magnetized water might have minimized the DNA damage by improving the antioxidant status of the mice. However, further studies are needed to characterize the condition of the magnetization and examine the long-term effect of the water product.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.247-247
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• 2017

Byobusan area of Aomori prefecture in Japan was a marshy sand dune and had developed for agricultural land use with a large-scale sprinkler system. Recently, it becomes an agricultural problem at this area that distinctive damage with browning maculation and fissures frequently occurs in Chinese yam tubers. Acetaldehyde is one of the factor candidates of underground part damage in plants. In this study, incidence rate of the tuber damage, and the morphological character and elemental composition of the damage parts in tubers were investigated with applications of excessive irrigation water or acetaldehyde water solution into the yam field. The incidence rate of the distinctive tuber damage increased as the input amount of irrigation water was increased. At the browning maculation parts of the tubers, many fissures and damages of cork layer were observed under scanning electron microscopy. In addition, the periderm of tubers was significantly thicker in damaged parts than in non-damaged parts. Funguses, bacterium and nematodes were not observed in the damaged part under scanning electron microscopy. The weight ratio of each constituent element in an analyzed area relative to the total weight of major essential elements was measured with energy dispersive X-ray spectrometry. The results showed that the weight ratios of boron, carbon, phosphorus, sulfur and calcium were higher in damaged parts than in non-damaged parts whereas the weight ratios of oxygen and chlorine were lower in damaged parts than in non-damaged parts. It was also shown by this spectrometry that iron, cadmium, lead and zinc were not directly involved in occurrence of the tuber damage. In this study, there was no remarkable difference of tuber appearance between non-acetaldehyde and acetaldehyde application treatments. From the above results, it is shown that the damage would be a physiological disorder induced by the input of a large quantity of water in the sandy field.