• Journal of Environmental Science International
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• v.25 no.5
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• pp.727-736
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• 2016

The ambient mass concentration and chemical composition of the $PM_{2.5}$ were determined at the highland site with 1,100 m above sea level on Jeju Island from June 2013 to November 2014. Yearly averaged mass concentration of $PM_{2.5}$ was $11.97{\pm}8.63{\mu}g/m^3$. $PM_{2.5}$ concentrations were highest during the spring, while they tended to be lowest during the summer. Eight water soluble ionic species attributed 45.5% to $PM_{2.5}$ mass. $SO{_4}^{2-}$, $NO_3{^-}$ and $NH_4{^+}$ were major ions, which occupied to 27.9%, 3.7% and 12.3%, respectively. The greatest contributors to total mass concentration of water-soluble ions contained in $PM_{2.5}$ were sulfate, ammonium and nitrate. These three ions accounted for 96.6% in total ions mass concentration of $PM_{2.5}$. We could infer that these three secondary ions exist mostly in the form of $(NH_4)_2SO_4$ and $NH_4NO_3$. $Ca^{2+}$ and $Mg^{2+}$ had a good relationship and with r=0.9. The molar ratio of $Mg^{2+}/Ca^{2+}$ in this study was lower than the value observed in sea water and higher than that in soil dust, indicating that these two ions originated from other sources rather than ocean and soil dust in this study.

• The Korean Journal of Pesticide Science
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• v.19 no.1
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• pp.1-4
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• 2015

The current official perfluorochemicals (PFCs) analysis method is established with hydrophilic-lipophilic balance (HLB) solid phase extraction (SPE) clean-up method with LC-tandem mass spectrometry ($MS^n$). Herein the HLB clean-up method from the official method by Korean government was modified with Envi-Carb$^{TM}$ to improve the clean-up efficiency for agricultural water and the unexpected UV disturbance in the water was effectively removed by the adsorbent treatment without a significant disturbance of quantitation. And quadrupole time of flight mass spectrometry (qTOFMS) was suggested to the available $MS^n$ instruments for the residue analysis of PFCs based on the ng/L of quantitation limits in water as well.

• Nutrition Research and Practice
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• v.8 no.5
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• pp.580-588
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• 2014

BACKGROUND/OBJECTIVES: The objective of the study was to provide useful insights into plain water intake of Korean adults according to life style, anthropometric, and dietary characteristics. SUBJECTS/METHODS: The data from the 2008-2010 Korea National Health and Nutrition Examination Survey were used. The subjects were 14,428 aged 20-64 years. Water intake was estimated by asking the question "How much water do you usually consume per day?". Dietary intake was estimated by 24-hour dietary recall. A qualitative food frequency questionnaire including 63 food items was also administered. RESULTS: The mean plain water intake for men and women were 6.3 cup/day and 4.6 cup/day, respectively. Plain water intake increased as lean body mass, waist circumference, and body mass index levels increased, except for percentage of body fat. As energy and alcohol intakes increased, plain water intake increased. As total weight of food intake and total volume of food intake increased, plain water intake increased. Plain water intake increased as consumption of vegetables increased. Plain water intake increased as frequencies of green tea, alcoholic drink, and all beverages were increased in men. Plain water intake increased with increased frequencies of green tea, milk, soy milk, and alcoholic drink and decreased frequencies of coffee and soda in women. CONCLUSIONS: Our results suggest that persons who had a higher waist circumference or lean body mass and women with higher BMI consumed more plain water. The persons eating high quality diet, or the persons who had more vegetables, green tea, milk, soy milk, or alcoholic drink consumed more plain water.

• Ocean and Polar Research
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• v.24 no.2
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• pp.153-166
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• 2002

Particle fluxes were measured by using time-series sediment traps in the Bransfield Strait from December 27th, 1999 to December 26th, 2000. Total mass fluxes showed distinct seasonal variations with high fluxes in the austral summer and low fluxes in the austral winter at a 678m water depth in the eastern Bransfield Strait, while they were high only in January and fairly low in other months at a 960m water depth in the central Bransfield Strait. The reason that total mass fluxes occurred only in January at a 960m water depth in the central Bransfield Strait seems to be the strong current in the surface waters, which leads to a substantial amount of terrestrial materials and locally produced organic matter being advected away from the mooring site. Total mass fluxes were very high from January to October at a 1678m water depth in the eastern Bransfield Strait, while they were high only in January and February at a 1860m water depth in the central Bransfield Strait. The fact that total mass fluxes were higher at the deep water in the both sites than at the intermediate water depth may reflect that a substantial amount of terrestrial and organic materials are laterally transported by strong tidal current from the shallow environments to the deep basins.

• Nuclear Engineering and Technology
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• v.51 no.4
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• pp.987-995
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• 2019

Steam jet condensation is of great importance to pressure suppression containment and automatic depressurization system in nuclear power plant. In this paper, the condensation processes of sonic steam jet in a quiescent subcooled pool are recorded and analyzed, more precise understanding are got in direct contact condensation. Experiments are conducted at atmospheric pressure, and the steam is injected into the subcooled water pool through a vertical nozzle with the inner diameter of 10 mm, water temperature in the range of $25-60^{\circ}C$ and mass velocity in the range of $320-1080kg/m^2s$. Richardson number is calculated based on the conservation of momentum for single water jet and its values are in the range of 0.16-2.67. There is no thermal stratification observed in the water pool. Four condensation regimes are observed, including condensation oscillation, contraction, expansion-contraction and double expansion-contraction shapes. A condensation regime map is present based on steam mass velocity and water temperature. The dimensionless steam plume length increase with the increase of steam mass velocity and water temperature, and its values are in the range of 1.4-9.0. Condensation heat transfer coefficient decreases with the increase of steam mass velocity and water temperature, and its values are in the range of $1.44-3.65MW/m^2^{\circ}C$. New more accurate semi-empirical correlations for prediction of the dimensionless steam plume length and condensation heat transfer coefficient are proposed respectively. The discrepancy of predicted plume length is within ${\pm}10%$ for present experimental results and ${\pm}25%$ for previous researchers. The discrepancy of predicted condensation heat transfer coefficient is with ${\pm}12%$.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.4
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• pp.216-224
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• 2006

To clarify the formation process and characteristics of oxygen deficient water mass in Gamak Bay, oxygen deficiency was weekly observed from 17 June to 12 September 2005. Surface water temperature was significantly lower in the outer bay than in the inner bay, whereas the bottom water temperature was higher in the central area of bay than in the outer and inner bay. The vertical stratification of water mass was strongly formed during the period, and thermocline was observed between 3 and 5m deep. The oxygen deficiency in the bottom layer began to appear at early July in the inner bay and gradually spread to the center area of the bay in early August. The mean transparency and light attenuation coefficient($K_d$) in water mass was 4.0m and 0.47, respectively. Average concentrations of nutrient and chlorophyll ${\alpha}$ in the bottom layer were significantly higher than those in surface, and those concentrations were significantly higher in the inner bay than in the outer bay. During the formation of oxygen deficiency in the bottom layer, oxygen penetration depth in the bottom sediment were extremely shallow, and oxygen consumption rate in the bottom sediment were lower than that in the area where oxygen deficient water mass disappeared. Dissolved oxygen concentrations in the bottom layer are negatively correlated with nutrient concentrations, whereas those in the surface layer did not show a significant relationship with nutrient concentrations. Elevated loss of oxygen in the bottom water mass was attributed to the increase of the oxygen consumption rates in sediments and the decomposition of organic matter by microorganism.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.304-310
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• 2001

A numerical model which simulates the heat and mass transfer processes within a counter-current plate type generator for ammonia/water absorption refrigerators was developed. Ammonia/water solution flows downward under gravity and ammonia/water vapor generated by flow boiling flows upward. The flow pattern within the generator was assumed to be a bubbly flow, and the liquid and vapor phase were assumed to be saturated. It was shown that the boiling of ammonia occurred mainly in the upper part of the generator. The effects of the generator length, the wall temperature and the mass flow rate of ammonia/water solution into the generator on the generation of ammonia/water vapor were investigated.

• Journal of the korean society of oceanography
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• v.32 no.1
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• pp.17-27
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• 1997

Miami Isopycnic Coordinate Ocean Model is applied to the East Sea to estimate the renewal time of the upper Intermediate Water The model gives about 10 years of renewal time. Extrapolating this result to the whole water mass below, including the upper Intermediate Water, leads to about 81.4 years of renewal time, which is quite comparable to that obtained by Kim and Kim (1997) based on the recent observations. Deep winter mixing occurs in the north of the basin. The areas of the largest water mass conversion, from the upper mixed to the intermediate below, are along the periphery of the deep mixing zone. Large portion of the renewed Intermediate Water then advects along the Korean and Japanese coasts. It is concluded that the high-oxygen content Intermediate Water found off the Korean coast (Kim and Chung, 1984) is in part locally formed but mostly advected from the deep mixing zone.

• Journal of Biosystems Engineering
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• v.19 no.1
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• pp.62-69
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• 1994

This study was designed to seek information on the heat charging and discharging characteristics of a multi-capsule type LTES(Latent Heat of Fusion Thermal Energy Storage) system, and especially prediction equation of outlet water temperature from the system. During heat charging process, the water temperature in the LTES tank increased very slowly in comparison with a predicted one and was kept near the melting point of the PCM for about 25 minutes. During heat discharging process, the latent heat discharging period of the outlet water temperature became longer as the inlet water temperature became higher and/or mass flow rate became lower. The dimensionless temperature of the outlet water was predicted by linking three equations of ${\theta}=1.1Exp(-{\tau}/0.82)$, ${\theta}=-0.06{\tau}+0.3$, ${\theta}=0.8Exp(-{\tau}/1.4)$ ($r^2{\leq}0.88$) depending on discharging period regardless of mass flow rates on the case of the inlet water temperature at $21.5^{\circ}C$.

• Geomechanics and Engineering
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• v.18 no.1
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• pp.1-9
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• 2019

In this study, both 2D and 3D failure shapes of rock mass above the water-filled cavity are put forward when the surrounding rock mass cannot bear the pressure caused by the water-filled cavity. Based on the analytical expressions derived by kinematic approach, the profiles of active and passive failure patterns are plotted. The sensitivity analysis is conducted to explore the influences of different rock parameters on the failure profiles. During the excavation of the deep tunnels above the karst cavity, the water table always changes because of progressive failure of cavity roof. Therefore, it is meaningful to discuss the effects of varying water level on the failure patterns of horizontal rock layers. The changing laws of the scope of the failure pattern obtained in this work show good consistency with the fact, which could be used to provide a guide in engineering.