• Nuclear Engineering and Technology
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• v.47 no.1
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• pp.135-138
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• 2015

A new correlation predicting the idealized critical mass-flow rates of water for subcooled and saturated liquid water including two-phase water flow was developed for a wide range of upstream stagnation pressures (e.g., 0.5-20.0 MPa). A choking correction factor dependent on the upstream stagnation pressure and subcooled temperature was introduced into a new correlation, and its values were suggested to satisfy the idealized nozzle data within 10% error ranges. The suggested correlation will be instructive and helpful for related studies and/or engineering works.

• Journal of Ocean Engineering and Technology
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• v.10 no.2
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• pp.136-145
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• 1996

The theory is based on two thermodynamic equations for the air mass in the air column and bydrodynamic equation for the relation between the response of the air in the water column and the incident wave. The numerical model is experimented in a two dimensional water tank and the caisson model with sloped front wall is tested in the large towing tank.

• Journal of Energy Engineering
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• v.8 no.4
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• pp.546-552
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• 1999

In order to obtain the highly effective thermal energy from jacket cooling water of propulsion diesel engines. a development of the Fresh Water Generator (FWG) with a capacity of 30 ton/day was implemented. Newly developed experimental devices and data acquisition system were used to evaluate the performance of the FWG. In this study experiments were performed for various driving pressures by varying the mass flowrate of cooling seawater with or without a heat source instead of jacket cooling water.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5425-5433
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• 2014

This study examined the effects of the key parameters on the power efficiency of the waste heat power plant using the EES program to obtain data for the design of the 20kW Kalina power plant. The parameters include the ammonia mass fraction, vapor pressure, heat source temperature, and the cooling water temperature. According to the analyses, a lower ammonia mass fraction and a higher vapor pressure increase the efficiency, in general. On the other hand, this study shows that there is a specific region with a very low ammonia mass fraction, where the efficiency decreases with ammonia mass fraction. Regarding the vapor pressure at the turbine inlet, the power efficiency increases with increasing vapor pressure. In addition, it was found that the influence of the vapor pressure on the efficiency increases with increasing ammonia mass fraction. Finally, the optimal condition for the maximum power efficiency is defined in this study, i.e., the maximum efficiency was 15% with a 25bar vapor pressure, $160^{\circ}C$ heat source temperature, $10^{\circ}C$ cooling water temperature, and 0.4 ammonia mass fraction.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.339-344
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• 2010

Oxygen depleted water mass can damage aquatic animals not only in direct way but also in indirect way by generating toxic substances including occurrence of hydrogen sulfide and ammonia which are also highly detrimental to animal life in the water mass. An oxygen dissolution device was developed, which makes turnover of the oxygen rich (over 20 mg/L) surface water down to the bottom where hypoxia is evident and tested the device in terms of oxygen recovery in the oxygen depleted bottom water. the device with turnover rates of $3.6\;m^2$/min at the liquid oxygen injection rate of 48~26.3 L/min could recover dissolved oxygen level to 7~25 mg/L at depth 7 m to lead to the dissolution level of over 90% by the supply of liquid oxygen. The running advantage of the device is that it does not require any auxiliary tank and higher energy for operation. Therefore, it can be highly useful device to relieve damages to the farmed animals in the oxygen depleted waters.

• Journal of Korea Water Resources Association
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• v.41 no.3
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• pp.243-249
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• 2008

Continuous stirred tank reactor(CSTR) model which can be applied to control and management of the surface flow wetland is developed to simulate the water quality in this research. The model solution is obtained from the optimization model using the least-squares and 4th-order Runge-Kutta methods. The model is applied to simulate BOD and TSS in the wetland database of U.S. EPA, in which the hydraulic and water quality data are enough and the number of pond is just one for simple analysis of running results. The model is tested in two different cases, one constant volume case and another constant volume and flow rate case considering only reaction term, mass flux term and both reaction and mass flux terms respectively. It is found that the model simulates the real water quality very well with both reaction and mass flux terms rather than only reaction term and the settling velocity of TSS becomes $0.3{\sim}0.4\;m/d$. The model can be applied in wetlands treatment efficiently.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.534-534
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.501-503
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• 2005

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.649-658
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• 2020

The purpose of this study is to verify the difference in health and obesity according to water and coffee intake. The study subject is 900 female college students. Physical fitness factors measured in this study were physical strength(grip strength, back muscle strength), muscle endurance (sit-up), Flexibility(Sit & reach) and cardiopulmonary endurance(harvard step). The factors of body composition (intracellular fluid, extracellular fluid, protein, mineral, body water content, muscle mass, lean body mass, body fat mass) and obesity (BMI, body fat percentage, abdominal fat percentage, obesity) were measured with the Inbody equipment. SPSS program was used for all data analysis. Group differences were verified by two-way ANOVA and one-way ANOVA. The results are as follows. There was no interaction effect between water and coffee intake on health and obesity. Therefore, the difference of the dependent variables according to each independent variable was verified. There was no significant difference in physical fitness according to water intake and coffee intake, but there was a significant difference in body composition (intracellular fluid, protein, minerals, body water, muscle mass and lean body mass). Water drinking group more than 7 cups had significantly higher body composition than the 1-4 cups water drinking group. In the case of coffee, the body composition of the 3 cup intake group was significantly higher than that of the none intake group. Obesity was significantly higher than the none intake and 1-2 cup intake groups. Based on the study results, water intake was not related to obesity, but coffee was related. For further studies, it would be better to consider gender and age differences in drinking various beverages such as water and coffee and that would be used to suggest a desirable way of water intake according to individual characteristics of the better health.

• Proceedings of the Microbiological Society of Korea Conference
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• 2002.10a
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• pp.86-89
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• 2002