• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.11
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• pp.1447-1456
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• 2000

Simulated experiments of high pressure melt ejection(HPME) are performed to measure the released fraction of corium simulant from the French type PWR cavity. The experiments are carried out on a 1/20th linear scaled model of the Ulchin 1&2 cavity. Water or woods metal and nitrogen is used as simulant of molten corium and steam, respectively. Experimental parameters are water mass, annulus area and breach size. It is shown that only breach size effects is very important while the mass and the annulus area do not affect the released fraction. It is found that the liquid film transport is much more dominant mechanism than the entrainment droplet transport, especially in linear scale down simulated HPME experiment.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.9
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• pp.511-516
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• 2015

On this study, we investigated the removal characteristics of residual chlorine and DBPs in tap-water during boiling. Also we investigated the releasing characteristics of essential minerals in infusion tea. While recent studies focused on removal mechanisms of harmful heavy metals in infusion tea, this study tried to suggest the way to drink tap-water healthier and safer by examining releasing mechanisms of essential minerals in infusion tea. As a result, residual chlorine(initial conc. was 0.7 mg/L) was all removed in 20 minutes after heating and DBPs (the sum of THMs, HAAs and CH) were removed up to 65%. 6 kinds of essential minerals (Ca, K, Na, Mg, S, P) were released from 5 kinds of infusion tea (barley tea, corn tea, brown rice tea, cassia seed tea, solomon's seal tea) on the market. In cassia seed tea, the amount of essential minerals released from tea showed the highest values, 9.6 mg/g, and brown rice tea was the lowest, 1.6 mg/g. Particularly, the released amounts of potassium, playing a key role in human body in maintaining normal blood pressure, cell metabolism and enzyme action, showed relatively high. Through this study, we got to know that essential minerals can be obtained up to 40% of recommended nutritional intake for Korean by boiling tap-water with infusion tea.

• Ocean and Polar Research
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• v.26 no.4
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• pp.635-646
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• 2004

Chronic outbreaks of green tide in the Nakdong estuary toll a heavy socioeconomic cost. The paper investigates the influence of sediments on the nitrogen eutrophication, being claimed as the primary cause of green tide. To measure the flux of nitrate at the sediments-water interface, sediment cores were taken in Jan., Mar., May and Sep., 2000 at Noksan located in the West-Nakdong river estuary. The dissolved oxygen was profiled and then the pore water was extracted in situ. Core samples were analyzed for their textural characteristics. Cores were incubated by a novel technique to measure the fluxes of nitrate $(NO_3^-)$ and ammonia $(NH_4^+)$ at the sediment-water interface. The dissolved oxygen was depleted usually within several millimeters in the top sediments. Nitrate started to decrease drastically at the layer where dissolved oxygen was nearly depleted. Nitrate was also exhausted within several centimeters, followed by ammonia build up rapidly. The flux at the sediments-water interface calculated from the pore water concentrations revealed that nitrate was removed from the water column into the sediments. The sediment incubation experiment confirmed the above result. On the other hand ammonia were released from the sediment to the water column. As the incubation went on, however, the nitrate concentration in the overlying water was dropped below that of a top sediment. Then the flux is reversed, i.e., nitrate was released from the sediments to the water column. The implication is that the sediment can supply nitrate to the water column if it falls below a certain level. Thus it is likely that sediments in the eutrophicated river buffers the nitrate concentration in the water column, which leads to a prolonged green tide.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.591-599
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• 2007

The quality of water released from a stratified reservoir is dependent on various factors such as the location and shape of intake facility, structure of reservoir stratification, profile of water quality constituent, and withdrawal flux. Sometimes, selective withdrawal capabilities can provide the operational flexibility to meet the water quality demands both in-reservoir and downstream. The objective of this study was to evaluate the performance of a one-dimensional reservoir selective withdrawal model (SELECT) as a tool for supporting downstream water quality management for Daecheong and Imha reservoirs. The simulated water quality variables including water temperature, dissolved oxygen (DO), conductivity, turbidity were compared with the field data measured in tailwater. The model showed fairly satisfactory results and high reliability in simulating observations. The coefficients of determinant between simulated and observed turbidity values were 0.93 and 0.95 for Daecheong and Imha reservoirs, respectively. The outflow water quality was significantly influenced by water intake level under fully stratified condition, while the effect of intake amount was minor. In conclusion, the SELECT is simple but effective tool for supporting downstream water quality prediction and management for both reservoirs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.4
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• pp.348-355
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• 2002

To know characteristics of water quality in Saemankeum area, we were investigated the water quality of surface layer from July of 1999 to June of 2000. The concentrations of COD and chlorophyll a were in the range of $0.64\~6.40$ (mean 1.96)mg/L, $1.95\~51.55$ (mean 11,07)$mg/m^3$, respectively. The annual mean concentrations of DIN, DIP were found to be 21.182 $\mu$g-at/L and 0,655 $\mu$g-at/L respectively, which were exceeding second grade of seawater quality standard. The nitrogen ratio to the phosphorus was lower than 1. Therefore, nitrogen was playing an important role in phytoplankton growth as limiting factor in study area. Mean values of eutrophication index were exceeding 1, which was the eutrophication criteria. Especially Mankyung and Dongjin estuary were shown over 10 as eutrophication index. Therefore, Saemankeum area could be evaluated to possibility area for eutrophication. Released rate for ammonia nitrogen and phosphate phosphorus from sediments were 62.92 ${\mu}g-at/m^3/hr$ and 6.71 ${\mu}g-at/m^3/hr$, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.1
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• pp.52-61
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• 1998

Nitrification and denitrification are important processes in the landfill site as they are deeply related with degradation and stabilization of refuse. Also nitrous oxide ($N_2O$) which is released from both nitrification and denitrification is known as greenhouse gas (GHG). The purpose of this study was to clarify the process by which $N_2O$ produced using $^{15}N$ isotope. Nitrate which was labeled to 10.08% with $^{15}KNO_3$ was used and $N_2O$ was analyzed with GC mass. Results was that even also when $O_2$ of bulk was 15%, $N_2O$ was released from denitrification. And as concentrations of $O_2$ increase, sum of $N_2O$ was released from denitrification. And as concentrations of $O_2$ increase, sum of $N_2O$ and $N_2$ was decreased and ratios of $N_2O$ in the reduced gases were increased. FISH technics also adaped to confirm whether which of nitrifiers existed in the substrates. When NEU was used of which the target was ammonia oxidizing bacteria, nitrifier was not detected at all. So it was confirmed that during the reaction denitrification was dominant process. Total bacteria distributions which were detected by EUB probe explained that as $O_2$ increase the number of bacteria also increase, but between the 10-15% of $O_2$ there was no any differences.

• Journal of the Korean Ceramic Society
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• v.17 no.3
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• pp.158-162
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• 1980

The experiments of suspension hydration were performed in the mixtures of slag and water or NaOH solutions which were made up with a liquid/solid ratio of 10. The liquid phase of the suspension was chemically analysed and discussed. When slag was in contact with water, CaO component was released from slag grains into the solution. The amounts of $SiO_2$ and $Al_2O_3$ liberated in the solution were very low as compared with CaO, for the impermeable coating of $SiO_2$, $Al_2O_3$-rich gel was formed on the surface of slag grains. The hydration was considered to be inhibited by this impermeable coating. The weak hydraulic property of slag was based on slowly released CaO and dissolved Na, K components which increased pH in the solution.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.7 s.238
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• pp.970-975
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• 2005

This paper presents a novel microgenerator of $CO_2$ (carbon dioxide) gas. $NaHCO_3$ (sodium bicarbonate) in a chamber is decomposed by the underlaid microheater. Alternatively, water droplet is caged by paraffin layer and released by heating. The released water dissolve HOC(COOH)$(CH_2COOH)_2$ (citric acid) powder and then, $NaHCO_3$ reacts with the solubilized HOC(COOH)$(CH_2COOH)_2$ and $CO_2$ is produced. Micropumps actuated by $CO_2$ generation were fabricated. A portable micro cell incubator of which pH is controlled by the produced $CO_2$ is also presented as one of the further applications.

• Journal of Pharmaceutical Investigation
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• v.39 no.4
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• pp.257-261
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• 2009

Effective therapeutics for renal failures have not yet been developed until now. Recently, there was a report showing that Wen-pi-tang-Hab-Wu-ling-san (WHW) prescriptions had the potential to prevent renal failures through the increased expression of HSP-27 and HSP-72 after ischemia/reperfusion. Therefore, formulation studies by pH-specific released systems were carried out to exhibit the optimal activity of WHW prescriptions in this study. WHW prescriptions were separately extracted using water into two parts of stomach-released (SR) and intestine-released (IR) extracts. Subsequently, the double-layered tablet was prepared using the SR extracts and pharmaceutical additives and enteric-coated IR tablet. Dissolution studies were carried out to figure out the release of cinnamic acid and icarrin from SR tablet, IR tablet and double-layered tablet, respectively. The complete release of cinnamic acid from SR tablet showed 90min after dissolution in pH 1.2 and insignificant drug released from IR tablet. As well as, icarrin from IR tablet completely released in pH 6.8 and 7.4 as enteric-coating film dissolved.

• Journal of Radiation Protection and Research
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• v.26 no.2
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• pp.79-86
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• 2001

This study presents the quantitative exposure assessment of indoor radon released from groundwater. Most of the Indoor radon comes directly from soil beneath the basement or foundation. Recently, radon in groundwater releases to indoor air whenever the water is used and contributes to the total inhalation risk from indoor air. This study first develops a mathematical model to describe the transfer and distribution of radon released from groundwater in a house. Then, daily human exposures through inhalation or such radon are estimated with the model for an male adult based on two sets of exposure scenarios. The results obtained from the study would help increase the understanding of risk assessment issues associated with the indoor radon released from groundwater.