• Reproductive and Developmental Biology
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• v.37 no.3
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• pp.97-102
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• 2013

The objective of this study was to develop of semen transport system for cryopreservation and fertility in bull sperm. The ejaculated semen were diluted with Triladyl containing 20% egg-yolk for transportation. Diluted semen was transported by three methods that there were wrapping tissue (Tissue), sinking under $30^{\circ}C$ water (Water) and sinking between warm water and air (Air) methods. Semen was transported within 2 hours in $0.3^{\circ}C$. For this study, the freezing of diluted semen were added with Triladyl containing 20% egg-yolk. And frozen-thawed sperm were estimated with SYBR14/PI double stain for viability, FITC-PNA/PI double stain for acrosome reaction analysis and Rhodamine123 double stain for mitochondrial intact assessment. In results, live sperm (SYBR+/PI-) in Air treatment group ($43.3{\pm}4.7%$) was significantly (p<0.05) higher than other treatment groups (Tissue: $16.3{\pm}2.7%$ and Water: $27.5{\pm}3.1%$), dying sperm (SYBR+/PI+) in Air treatment group ($55.6{\pm}4.7%$) was significantly lower than other treatment groups (Tissue: $77.6{\pm}3.2%$ and Water: $67.6{\pm}3.3%$) (p<0.05). Acrosome reaction in Air treatment group ($0.2{\pm}0.1%$) within live sperm (PI negative region) was significantly (p<0.05) lower than other treatment groups (Tissue: $0.7{\pm}0.2%$ and Water: $0.5{\pm}0.1%$), the acrosome reaction in Air treatment group ($28.6{\pm}2.8%$) within all sperm also was significantly lower than other treatment groups (Tissue: $44.2{\pm}1.8%$ and Water: $36.2{\pm}2.0%$) (p<0.05). And mitochondrial intact in Air treatment group within live ($97.1{\pm}0.4%$) and all ($61.9{\pm}3.3%$) sperm were significantly higher than other treatment groups (Tissue: $85.2{\pm}3.3%$, Water: $87.8{\pm}2.9%$ within live sperm and Tissue: $49.28{\pm}3.7%$, Water: $42.0{\pm}3.1%$ within all sperm) (p<0.05). Therefore, we suggest that transportation by sinking method between warm water and air was beneficial to improvement of fertility in frozen-thawed in bull semen.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.2
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• pp.10-21
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• 2022

A water source heat pump (WSHP) system is regarded as an energy-efficiency heating and cooling supply system for buildings due to its high energy efficiency and low greenhouse gas emissions. Recently, water sources such as river water, lake water, and raw water are attracting attention as heat sources for a heat pump system in Korea. This paper analyzed the applicability of a river water source heat pump system (RSHP). The river water temperature level was compared with the outdoor air and ground temperature levels to present applicability. In addition, the cooling and heating performance were compared through a simulation approach for the RSHP and a ground source heat pump (GSHP) applied to a large-scale office building. To compare the temperature level, the actual data were applied to the river water and the outdoor air, while the simulation results were applied to the ground circulation water. The results showed that the change in river water temperature throughout the year was similar to the change in outdoor air temperature. However, unlike the outdoor air temperature, the difference between the hourly and daily average river water temperatures was not large. The temperature level of river water was lower during the heating season and somewhat higher during the cooling season than that of the ground circulation water. Finally, the performance of the RSHP system was 13.4% lower than that of the GSHP system on an annual-based.

• Nuclear Engineering and Technology
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• v.31 no.6
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• pp.548-560
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• 1999

An experimental investigation has been peformed to examine the effects of various geometrical parameters and an initial operating condition on the air-water countercurrent How limitation (CCFL) in a simulated PWR hot leg. A total of 118 experimental data for the onset of CCFL and zero liquid penetration were obtained for various combinations of test parameters. It was observe that the CCFL can be classified into three different categories: (the onset of CCFL, (the partial liquid delivery, and (r) the zero liquid penetration. The observed mechanisms of the onset of CCFL were different depending on the inlet water flow rate. The parametric effects of pipe diameter, horizontal pipe length, horizontal pipe length-to-diameter (L/D) ratio, and initial water level in the horizontal pipe of the test section on the onset of air-water CCFL were also examined. An empirical correlation for the onset of CCFL in a horizontal pipe connected to an inclined riser was developed in terms of Wallis flooding parameters for the low inlet water flow rate region. Comparisons of the present empirical correlation with the air-water CCFL data of large pipe diameters show that the present correlation agrees more closely with the experimental data than the existing CCFL correlations.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.4
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• pp.345-352
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• 2008

The motion of a projectile initiated by the release of highly pressurized air is simulated presuming the flow field as a two dimensional one. The effects of water compressibility on projectile movements are investigated, comparing results based on the Fluent VOF model where water is treated as an incompressible medium with those from the presently developed VOF scheme. The present model considers compressibility of both air and water. The Fluent results show that the body moves farther and at higher speeds than the present ones. As time proceeds, the relative difference of speed and displacement between the two results drops substantially, after acoustic waves in water traverse and return the full length of the tube several times. To estimate instantaneous accelerations, however, requires implementation of the water compressibility effect as discrepancies between them do not decrease even after several pressure wave cycles.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.6
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• pp.521-528
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• 2005

This study has been conducted to investigate the potential energy reserve amount of river water as energy resource with useful temperature difference. Since the river water temperature is one of the primary parameters deciding the potential amount of river water energy reserve amount, the climate change effects on it are critically important. In this study, the heat exchange processes and the inter-relationship between the air temperature and river water temperature have been theoretically analyzed. Based on the present study, the potential energy reserve of river water is calculated to amount to 192,000 Tcal/year. Among this, it is estimated that approximately 2,000 Tcal/year can be directly utilized for heat pump energy sources.

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.3892-3901
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• 2021

The pressure drop of a moisture separator in a steam generator is the important design parameter to ensure the successful performance of a nuclear power plant. The moisture separators have a wide range of operating conditions based on the arrangement of them. The prediction of the pressure drop in a moisture separator is challenging due to the complexity of the multi-dimensional two-phase vortex flow. In this study, the moisture separator test facility using the air/water two-phase flow was used to predict the pressure drop of a moisture separator in a Korean OPR-1000 reactor. The prototypical steam/water two-phase flow conditions in a steam generator were simulated as air/water two-phase flow conditions by preserving the centrifugal force and vapor quality. A series of experiments were carried out to investigate the effect of hydraulic characteristics such as the quality and liquid mass flux on the two-phase pressure drop. A new prediction model based on the scaling law was suggested and validated experimentally using the full and half scale of separators. The suggested prediction model showed good agreement with the steam/water experimental results, and it can be extended to predict the steam/water two-phase pressure drop for moisture separators.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.2
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• pp.128-135
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• 2007

In response to anthropogenic global warming due to a buildup greenhouse gas, the effect of the air temperature on water temperature has been noticed. Therefore, effects have been made to build an air/water temperature relationship at three study regions using the data collected by the Ministry of the Maritime Affairs and Fisheries (MOMAF). The air/water relationship varies with time-scale and weekly time-scale was chosen for the study. The data were fitted to the S-shaped non-linear relationship, and the parameters for the S-curve were derived using a single-criteria multi-parameter optimization scheme. Separate regression curves were fitted to consider seasonal hysteresis at the Masan site. The study results support the S-shaped non-linear relationship is the best fit for the air/water relationship at the Korean coastal zone. This study will contribute to determine the future policy regarding water quality and ecosystem for the decision-driving organization.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.5
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• pp.233-240
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• 2015

This paper discusses compressors operating number control strategy using cooperative logic to cope with variable partial load for high efficiency of a centrifugal water chiller. The cooperative logic is composed of a speed-up and speed-down controller, enabling smooth operation of compressors and equivalent distribution of thermal load in each compressor. This centrifugal water chiller design can be operated with high efficiency without incurring excessive energy waste and large transient phenomena at partial load states. Simulations in MATLAB and experiments in a real chiller system were conducted and verified the high efficiency control of a centrifugal water chiller achieved by the suggested strategy.

• Nuclear Engineering and Technology
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• v.46 no.6
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• pp.817-824
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• 2014

To ensure the safety of research reactors, the water level must be maintained above the required height. When a pipe ruptures, the siphon phenomenon causes continuous loss of coolant until the hydraulic head is removed. To protect the reactor core from this kind of accident, a siphon breaker has been suggested as a passive safety device. This study mainly focused on two variables: the size of the pipe rupture and the timing of air entrainment. In this study, the size of the pipe rupture was increased to the guillotine break case. There was a region in which a larger pipe rupture did not need a larger siphon breaker, and the water flow rate was related to the size of the pipe rupture and affected the residual water quantity. The timing of air entrainment was predicted to influence residual water level. However, the residual water level was not affected by the timing of air entrainment. The experimental cases, which showed the characteristic of partical sweep-out mode in the separation of siphon breaking phenomenon [2], showed almost same trend of physical properties.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.169-169
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• 2003

In Korea, there is no CRA studies and has not well known CRA and not well established their methodologies. Therefore, objectives of this study is to establish the framework of CRA consisting of health risk, economic risk and perceived risk and the detail methodologies of three main component of estimating and comparing those risks for on the three environmental problems of air pollution, indoor air pollution and drinking water contamination which being subjective to the eight sub-problems of hazardous ai. pollutants (HAPs), regulated pollutants (representative as PM10) and Dioxins (PCDDS/ PCDFs) in air pollution, and indoor ai. pollutants (IAPs) and Radon in indoor air pollution, and drinking water pollutants (DWPs), disinfection-by- products(DBPs) and radionuclides in drinking water contamination in Seoul, Korea. And then, their problems set priorities by individual and integrated risk. As a results, ranking of health risk were the following order of indoor air pollution, air pollution and then drinking water contamination, in three environmental problems and of radon, PM10, IAPs, HAPs, DWPs, Dioxins, DBPs, and then radionuclides in eight sub-problems. And that of economic risk were the same order. In the contrary, ranking of perceived risk were the following order of air pollution, drinking water contamination, and then indoor air pollution, and of HAPs, Dioxins, radionuclides, PM10, DWPs, IAPs, Radon and then DBPs.