• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.2
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• pp.175-183
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• 2004

Performance of the water/air direct contact air conditioning system, in which heat and mass are directly transferred between air and water droplet, is simulated using semi-empirical method. Direct contact system improves transport efficiency compared to conventional indirect contact system. In this study, correlations for h$_{c}$A / c$_{pm}$ which represent the capacity of direct contact system are derived as a function of air and water flowrate from the experimental data. Cooling and heating performance of the water/air direct contact air conditioning system are evaluated using these correlations.ons.

• Environmental and Resource Economics Review
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• v.11 no.2
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• pp.321-333
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• 2002

Approximating bottled water consumption distribution is complicated by zero observations in the sample. To deal with the zero observations, a mixture model of bottled water consumption distributions is proposed and applied to allow a point mass at zero. The bottled water consumption distribution is specified as a mixture of two distributions, one with a point mass at zero and the other with full support on the positive half of the real line. The model is empirically verified for household bottled water consumption survey data. The mixture model can easily capture the common bimodality feature of the bottled water consumption distribution. In addition, when covariates were added to the model, it was found that the probability that a household has non-consumption significantly varies with some variables.

• Membrane and Water Treatment
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• v.10 no.5
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• pp.387-394
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• 2019

Membrane distillation (MD) is one of the water treatment processes which involves the momentum, heat and mass transfer through channels and membrane. In this study, CFD modeling has been used to simulate the heat and mass transfer in the direct contact membrane distillation (DCMD). Also, the effect of operating parameters on the water flux is investigated. The result shows a good agreement with the experimental result. Results indicated that, while feed temperature is increasing in the feed side, water flux improves in the permeate side. Since higher velocity leads to the higher mixing and turbulence in the feed channel, water flux rises due to this increase in the feed velocity. Moreover, results revealed that temperature polarization coefficient is rising as flow rate (velocity) increases and it is decreasing while the feed temperature increases. Lastly, the thermal efficiency of direct contact membrane distillation is defined, and results confirm that thermal efficiency improves while feed temperature increases. Also, flow rate increment results in enhancement of thermal efficiency.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.3
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• pp.241-248
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• 2010

Hypoxic(oxygen-deficient) water masses are a key threat to the ecosystem of shallow marine coastal areas worldwide. The phenomena of hypoxia occurred at Gamak Bay, on the southeast coast of Korea, in late June 2007. In this paper, the physicochemical characteristics of seawater were surveyed for a period of hypoxic water mass disappearance. The hypoxic water mass was located between Sunso and the northwestern area of the inner bay. The dissolved oxygen(DO) concentrations of surface and bottom water were $1.3mgL^{-1}$ and less than $2mgL^{-1}$, respectively, in the hypoxic water masses, and $4.5{\sim}6.8mgL^{-1}$ and $3.8{\sim}6.0mgL^{-1}$ at the other oxygen-rich sample sites, respectively. Chlorophyll a concentrations were $4.9{\sim}25.3{\mu}gL^{-1}$ at the surface, $2.3{\sim}23.1{\mu}gL^{-1}$ in the middle, and $1.9{\sim}9.0{\mu}gL^{-1}$ at the bottom of the hypoxic water masses. When the hypoxic water mass appeared in Gamak Bay, it formed three different vertical types. The first type occurred throughout the water depth around Sunso. The second type developed from the bottom. The third type of hypoxic water mass was formed in the middle water layer when the inversion of water temperature occurred. The third type of phenomena appeared at only St. 9, St. 14 and St. 21 sites near the Hodo coast. Aquatic surface respiration of bottom-dwelling fishes such as the oriental goby(Acanthogobius flavimanus) was observed and many crustaceans were seen along the adjacent shore of the hypoxic water mass area. About 3,000 oriental gobies as well as many crustaceans died due to this event in Gamak Bay. The results of this study could provide fundamental data for the mechanism of hypoxic water masses in Gamak Bay.

• Analytical Science and Technology
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• v.30 no.4
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• pp.194-204
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• 2017

Direct injection (DI) and solid phase extraction (SPE) methods for the simultaneous determination of pendimethalin (PDM) and dinoseb (DNS) in environmental water have been optimized using the ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. The limits of quantification (LOQs) of PDM and DNS were $0.01{\mu}g/L$ using the DI method and $0.0001-0.0002{\mu}g/L$ using the SPE method. The precision by SPE UPLC-MS/MS was less than 11 % for intra-day and inter-day analyses. When the proposed SPE method was used to analyze two analytes in environmental water, PDM was detected in a concentration range of $0.0002-0.011{\mu}g/L$ in 31 samples of the 114 surface water samples, and DNS was detected in a concentration range of $0.0005-0.045{\mu}g/L$ in 17 samples of the 114 surface water samples analyzed. When the DI method was used to analyze target compounds in the same samples, the detected concentrations of the two analytes were within 21% in samples with concentrations above $0.01{\mu}g/L$. The DI UPLC-MS/MS method can thus be used for the routine monitoring of PDM and DNS in environmental water, and the SPE LC-MS/MS method can be used for the determination of the ultra-trace PDM and DNS residues in environmental water.

• 한국해양학회지
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• v.18 no.1
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• pp.73-83
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• 1983

To serch the origin of the cold water mass along the east coast of Korea its characteristics are inrestigated based upon Cooperative Study of Kuroahio and Fisheries Research and Development Agency data. In the southwestern part of the Japan Sea the North Korean Cold Water sinks at the front and flows southwards on top of the Japan Sea Proper Water. it is found that the sunken North Korean Cold Water il high in the content of dissolved oxygen and less saline compared with the Japan Sea Proper Water. It is highly likely that the cold water mass off the Jugbyeon-Chuksan coast in summer il the North Koreah Cold Water and not upwelled Japan Sea Proper Water. It os shown that the Notth Korean cold Water Flows strongly in summer and its scuthern limit is generally off Chuksan-Janggigab and occasionally off Gampo as observed in 1973.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.783-784
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• 2010

• Journal of Environmental Science International
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• v.22 no.4
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• pp.425-433
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• 2013

A mass balance of process was calculated by using the analysis of basic unit and environmental assessment of all the processes of Busan fashion color industry cooperative that operates a combined heat and power plant and a bio treatment plant. The mass balance for the combined heat and power plant was done, based on boiler and water treatment processes while each unit reactor was used for the bio treatment plant. From the results above, a resource recycle network, a treatment flowchart for food waste water/wastewater treatment and a carbon reduction program were established.

• Analytical Science and Technology
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• v.11 no.2
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• pp.120-124
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• 1998

A rapid and accurate determination method of ultra-trace amounts of germanium in spring water by ICP-MS has been developed. Mass number 74 was not only the best mass but also the smallest mass interference. Only 30% of water samples contain germanium more than $0.1{\mu}g/L$, and a few of them has organogermanium species.

• Journal of Environmental Science International
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• v.20 no.7
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• pp.919-927
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• 2011

A ecosystem model was applied for understanding of circulation process of state variables in marine ecosystem. A mass balance was conducted by calculating the physical process. The sensitivity analysis was conducted to know which coefficient is the most effective factor to the state variables in the model. The results of the mass balance indicate that the primary production was 58.6 ton C/day in the case of mass flux. DIN and DIP in nutrient ingestion of phytoplankton were each 7.9 ton N/day, 1.1 ton P/day. POC and DOC in mineralization of organic matter were each 10.8 ton C/day, 40.6 ton C/day. The results of sensitivity analysis showed that the maximum growth rate of phytoplankton was the most important factor for overall state variables. In the case of nutrients, Half saturation constant of DIN, and mineralization rate of DOM for COD were important factor.