• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.159-166
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• 2011

The use of land cover was sharply changed during 1975~2007 in the Kyungan watershed $(561.12 km^2)$. The changes occurred over an area of more than $227.65 km^2$ during the overall period at changing rates of 1.04% per year for water area, 1.79% per year for residential area, 2.99% per year for bare area, 3.03% per year for wetland area, 3.04% per year for grass area, 0.87% per year for forest and 2.32% per year for agriculture area. Water, residential, bare and wetland areas increased, while grass, forest and agriculture areas decreased during the last 32 years. BOD concentrations of representative sites for each sub-watershed continuously increased until the early 2000s as residential area increased with the highest discharged load, but decreased after the mid 2000s except upper Kyungan watershed. Such decline appears to be associated with the planning of Total Maximum Daily Load management for Gwangju city and expansion of waste water treatment plant. It is necessary to control land use/cover changes of the upper watershed and to prepare appropriate watershed management system for improvement in river environment including water quality, stream flow and bio-diversity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.41-42
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• 2021

The Green New Deal policy was established to innovate the government's energy consumption structure, establish a third basic energy plan to strengthen the global competitiveness of the energy industry, and realize a carbon neutral society due to the increased need for transition to a low-carbon economy. Waterworks such as drinking water, water purification plant, and pressurization plant analyze control factors and energy consumption status by process to improve energy management efficiency and reduce energy usage through the 4th industrial revolution. Ultimately, we want to realize net-zero water purification plant.

• Journal of Korea Water Resources Association
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• v.32 no.5
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• pp.579-591
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• 1999

The operation of a reservoir system is necessary for establishing the operation rule as well as designing the reservoirs for water resources planning or management. Increasingly complex water resource systems require more advanced operation techniques. As a result, various techniques have been introduced and applied until now. In this study Linear Tracking model based on optimal control theory is applied to the operation of the largest scale multi-reservoir system in the Han river and its applicability proved. This system normally supplies the water resources required downstream for hydro-power and plays a role in satisfying the water demand of the Capital region. For the optimal use of the water resources the Linear Tracking model is designed with the objective to maximize the hydro-power energy subject to the water supply demand. The multi-reservoir system includes the seven main reservoirs in IIan river such as Hwachon, Soyanggang, Chunchon, Uiam, Cheongpyong, Chungju and Paldang. These reservoirs have been monthly operated for the past 21 years. Operation results are analyzed with respect to both hydro"power energy and water supply. Additionally the efficiency of the technique is assessed.sessed.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.4
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• pp.405-411
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• 1993

Several studies have shown that phytol isolated from perilla leaf and small water dropwort (Oenanthe javanica (BL) D.C., wild type) extract reveal antirumor activities. In the present study we investigated the effect of phytol and the small water dropwort extract on the T subset in the sarcoma 180-transplanted mice in order to elucidate the immunological mechanism of antiturmor activity of these substances. The results obtained from the experiment were as follows : When phytol was injected into the sarcoma-180 transplanted mice (control), the levels of T cell and T subset by inoculation of the tumor cells were enhanced, but that of T cells in case of small water dropwort extract was similar to the control. Asialo GM1$^{＋}$ cells were increased when phytol or small water dropwort extract with injected into tumor-transplanted mice. In normal mice the number of asialo GM1$^{＋}$ cells increased with phytol injection and decreased with small water dropwort extract injection. L3T4$^{＋}$/Lyt-2$^{＋}$cell ratios were decreased when phytol was injected into tumor-transplanted mire, but increased in case of small water dropwort extract injection. In normal mice the ratios showed large decreases with phytol or small water dropwort extract injection. These results indicate that phytol or small water dropwort extract ran activate the proliferation of natural killer cells that are effector cells in tumor-bearing mice.

• Journal of the Korean Wood Science and Technology
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• v.42 no.4
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• pp.460-466
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• 2014

To evaluate wood charcoal as raw material for mineral water production, dissolution of inorganic ions from charcoal to water, pH and adsorption ability of chlorine in water were investigated as main variables. More potassium ion was dissolved in water as higher temperature manufactured charcoal but other ions showed no difference with different charcoal making temperatures. Highest dissolved cation was potassium followed by calcium and sodium. Among wood species, charcoal from Quercus variabilis and Platanus occidentalis showed significantly higher potassium content in water than that of larch, red pine and white pine. Other cations had similar pattern to the potassium but their difference was not apparent as much as potassium. pH value of water treated with charcoal was higher for wood charcoals from Platanus occidentalis (pH 8.5) and Quercus variabilis (pH 8.4) which contained higher inorganic cations. In chlorine removal in water by charcoal, all wood charcoals showed greater chlorine removal than that of the control, but softwood charcoals resulted in higher removal than those of hardwoods. There was no significant difference in the dissolution of cations and pHs between particle charcoal and whole charcoal. With easy of control, whole charcoal is better for mineral water making raw material than particle charcoal does.

• Food Science and Preservation
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• v.14 no.5
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• pp.487-491
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• 2007

This study was conducted to investigate the effect of treatment with squeous chlorine dioxide and hot water on the germination of radish (Raphanus sativus L.) seeds, and reduction of microbial load on the seeds. Increases in treatment and the concentration of aqueous chlorine dioxide in water resulted in increasing reductions in the counts of total aerobic microbes. Seeds treated with aqueous chlorine dioxide (100 ppm/20min, 200ppm/20min) showed about a 10-fold decrease in microbial loads. Germination of seeds was not adversely affected by any treatment tested, although the germination rate of seeds in the group treated at $55^{\circ}C$ for 20 min was reduced by 10% compared to that of control. Combined treatment with hot water and aqueous chlorine dioxide yielded better out comes in both microbial reduction and seed germination rate than did single treatments. A combined treatment with 100 ppm aqueous chlorine dioxide and hot water($45^{\circ}C$ or $50^{\circ}C$) resulted in about a 100-fold decrease in microbial load whereas germination rate showed only a slight increase to $97.0{\sim}97.7%$. Total aerobic microbial counts in radish seeds were decreased by aqueous chlorine dioxide and hot water treatment in the order. aqueous $CIO_2$+ hot water > aqueous $CIO_2$ > chlorinated water > hot water > control.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.2
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• pp.189-195
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• 1997

To cope with increasing importance of water stress in food crop production, characteristics and cultivar differences in physiological responses of winter barley plants to water stress during seedling stage were studied employing three covered-barley, Milyang 12, Durubori, and Olbori, one naked-barley, Baekdong, and one two-row beer-barley, Hyangmaeg. Water stress was given to barley plants by withholding watering in soil-culture pots or by adding P.E.G. (polyethylene glycol, M. W. 4,000) to the nutrient culture solution. When water stress was imposed by withholding watering for 10 days to the seedlings grown in pot-soil for 10 days after emergence, leaf water potential of 5 cultivars was decreased almost to the same degree, from control -3.5 bar to the water stressed -26.6 bar. However, growth and some physiological responses were differently affected by cultivars: The plant height was decreased by 16-26％ : seedling dry weight by 25∼42％ ; chlorophyll content by 21∼39％ ; second leaf survival rate by 8∼18％ ; and free proline content per gram of leaf dry weight was increased from control 0.2∼0.5mg to the water stressed 5.8∼13.2mg. Drought resistances of 5 barley cultivars, based on the leaf survival rate and the decreased rate in seedling dry weight at the end of stress treatment, were high in the order of 3 covered-barley＞naked-barley＞two-row barley.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.289-300
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• 2013

In this study, two types of wetland plants, Eichhornia crassipes (a floating plant) and Ceratophyllum demersum (a submerged plant) were introduced to wetland mesocosms to understand how the water properties of wetlands such as pH, dissolved oxygen content, water temperature, oxidation reduction potential, and nutrient concentrations are affected by different types of wetland plant. The floating plant lives on the water surface and can block light penetration; it exhibited the lowest water temperature and temperature difference between lower and upper layers. After the addition of contaminants, the dissolved oxygen (DO) concentration decreased abruptly but recovered continuously in all mesocosms; especially the submerged plants, which photosynthesize in water, showed the largest increases in DO and diel periodicity DO, as well as in pH value. The oxidation-reduction potential in both water and sediment were affected by the presence of wetland plants and plant type and the results suggest that various aspects of wetland biogeochemistry are affected by the presence and type of wetland plants. The total nitrogen and phosphorous concentrations in water decreased in the following order: Water only < Water + Soil < Floating Plants < Submerged Plants. Although both floating and submerged plants can control algal concentrations, the effect was more prominent for floating plants.

• Journal of Bio-Environment Control
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• v.10 no.1
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• pp.1-9
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• 2001

Fruit growth in kiwifruit shows double sigmoid curve, but it does not certainly indicate as years. Therefore, I though the reason to be easy to the effect of water state change in kiwifruit, investigated diurnal change in water status of fruit tissues with an isoipiestic psychrometers against the fruit growth stage of kiwifruit in 1995 and 1996. Diurnal change in the fruit tissue water potential were little, but violent for fruti growth state III in 1996. The potential of two years dropped gradually approach to harvest time. On the other hand, osmotic potential of the tissues indicated to very similar to water potential, dropped rapidly -1.5MPa before dawn, recovered -1 MPa after 3 h on October 14, were -1~-1.7 MPa at the fruit commercial harvest in 1995. It had a tendency to lower in 1996 than in 1995. It was recorded to the minimum air temperature at the first for an autumn in 1995; 13$^{\circ}C$ from the middle night of October 13 to dawn of October 14. Leaves water potential, which is related to water status of xylem, nearly fell below -1 MPa at before dawn from stage II in 1996. However, it fell so low only at commercial in 1995. At the stage II, osmotic potential and ascent of the turgor pressure was high than 1995-fruit. There parameter suggested that three of kiwifruit in 1996 were status of water stress for stage III. The results from this study indicated that difference of fruit growth between 1995-fruit and 1996-fruit was affected by water status of the fruit tissues, which was influenced by weather condition.

• Journal of Korea Water Resources Association
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• v.51 no.12
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• pp.1207-1216
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• 2018

Discharge or water level predictions at tidally affected river reaches are currently still a great challenge in hydrological practices. This research aims to predict water level of the tide dominated site, Jamsu bridge in the Han River downstream. Physics-based hydrodynamic approaches are sometimes not applicable for water level prediction in such a tidal river due to uncertainty sources like rainfall forecasting data. In this study, TensorFlow deep learning framework was used to build a deep neural network based LSTM model and its applications. The LSTM model was trained based on 3 data sets having 10-min temporal resolution: Paldang dam release, Jamsu bridge water level, predicted tidal level for 6 years (2011~2016) and then predict the water level time series given the six lead times: 1, 3, 6, 9, 12, 24 hours. The optimal hyper-parameters of LSTM model were set up as follows: 6 hidden layers number, 0.01 learning rate, 3000 iterations. In addition, we changed the key parameter of LSTM model, sequence length, ranging from 1 to 6 hours to test its affect to prediction results. The LSTM model with the 1 hr sequence length led to the best performing prediction results for the all cases. In particular, it resulted in very accurate prediction: RMSE (0.065 cm) and NSE (0.99) for the 1 hr lead time prediction case. However, as the lead time became longer, the RMSE increased from 0.08 m (1 hr lead time) to 0.28 m (24 hrs lead time) and the NSE decreased from 0.99 (1 hr lead time) to 0.74 (24 hrs lead time), respectively.