• Journal of Korean Society of Water and Wastewater
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• v.20 no.6
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• pp.857-865
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• 2006

The submerged barrier, employed in a reactor, divided a reactor into sludge settling zone and mixing zone according to flow type. In spite of mixing in the mixing zone, the lower part of sludge settling zone than the top of barrier was in a steady flow due to the barrier, which prevented the turbulent flow, produced from the mixing zone, from being diffused into the sludge settling zone. Therefore, the sludges in the mixing zone flowed backward over the barrier into the upper part of the sludge settling zone by turbulent flow and settled down in the sludge settling zone by the force of gravity. When barrier/water level ratio was 0.5, most sludges almost did not settle down in tile sludge settling zone because the sludges were directly affected by the turbulent flow, generated from mixer in the mixing zone. At 0.63 of barrier/water level ratio, sludge in the middle part of sludge settling zone rocked from side to side weakly. And sludge in the lower part became piled up on the bottom over this ratio. After 10minutes of sludge settling, the lower part of sludge settling zone was over 5000mg/L of sludge concentration although intial sludge concentration was 2300mg/L. By using the submerged barrier and the flow types, it could transfer sludge from this to that.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.12
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• pp.999-1006
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• 2006

A study of temperature profiles in mixing zone of AHU (air handling unit) can contribute greatly to enhance performance of AHU system, so the study on the temperature distribution between RA (return air) and OA (outdoor air) is important to analyze the mixing characteristics in a mixing zone of AHU. Accordingly, the temperature profiles during RA (return air) and OA (outdoor air) supply process into mixing zone of AHU with an air mixer are studied experimentally. The effect of air mixer, OA temperature and RA/OA flow rate are studied in detail. In this study, the results show that the mixing efficiency is all high for installed the air mixer. The more OA temperature increase and OA flow rate decrease, the more mixing efficiency is high.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.153-158
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• 2004

The numerous investments have been introduced to design and assess mixing zone characteristics of wastewater discharges to the ocean. Specially It strive to meet water quality standard for persistent and bio-accumulative chemical contaminants at the point of discharge through continual improvement pollution prevention measures and other voluntary measures in the developed country. The goals that of this paper are to emphasize the regulatory mixing zone is defined as an allocated impact zone where the numeric water quality criteria may be exceeded as long as acutely toxic conditions are prevent. Furthermore, mixing zones be limited to an area or volume as small as practicable that with not interfere with the designated uses or the established community of aquatic life in the segment for which the uses are designated and the shape be a simple configuration that is easy to locate in the body of water and avoids impingement on biologically important areas and the shore hugging plumes should be avoided This results should be used with caution in evaluation the mixing zone characteristics of a discharge and only in conjunction with information from the effective marine outfall design as well as for the sound harbour design. Thus the numerical investigation using CORMIX has been performed to show the regulatory mixing zone in the near and far field of the marine outfall.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.455-458
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• 2002

Mixing zone characteristics of the wastewater effluents discharged from an ocean outfall have been investigated using an outfall mixing zone analysis method. This analysis was applied to Sokcho ocean outfall case and was used to simulate the concentration distribution of wastewater effluents. Hourly concentration distributions of outfall effluent discharges were averaged for the period of 15 days. The results show that near-field dilution was relatively high with the dilution of 130 for the winter season.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.2
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• pp.15-24
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• 2001

The concentration changes of discharged wastewater effluents due to ambient current flows and density stratifications in an outfall mixing zone have been investigated by using the outfall mixing zone analysis of Huang et al.[1996]. This analysis was applied to Masan sea outfall case and the concentration distributions of wastewater effluent discharges were simulated using three month period of current-meter data measured in the outfall site. Hourly concentration distributions of wastewater effluents were averaged for the period of 15 days which covers the flow conditions of the neap and the spring tidal currents in Masan Bay. The results show that the wastewater concentrations in the Masan outfall mixing zone were very low due to the higher dilution rates during the period of strong ambient currents and less density stratifications. The higher concentrations in the mixing zone were found in August because of strong density stratifications with low ambient currents. The mixing zone was extended to the west coast beach area because of major tidal current directions. This result can be used to explain the dynamical reasons for the depositional distribution of the contaminated sediments in Masan sea outfall area.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.539-540
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• 2006

It is so difficult to small amounts of two or more fluid species into single in microchannel because flows are usually laminar. In this regard multilamination micro mixer including recirculation zone is presented. Alternating feed micro channels make multilamination and converging-diverging channels form recirculation zone. Multilamination with geometric focusing decreases diffusion path ana recirculation zones make vortex. In this paper flow patterns and mixing properties of multilamination micro mixer including recirculation zone were investigated by Computational Fluid Dynamics (CFD). The CFD results provided qualitative information on mixing.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.247-253
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• 2004

As a large scale port development in coastal waters proceeds step by step and populations in the vicinity of port are getting increased, the issue on "how to dispose the treated municipal water and wastewater in harbor" brings peoples′ concern. The submarine outfall system discharges the primary or secondary treated effluent at the coastline or in deep water, or between these two. The effluent, which has a density similar to that of fresh water, rises to the sea surface forming plume or jet, together with entraining the surrounding sea water and becomes very dilute. We intended in this paper to investigate the impact on dilution of effluent and the behavior of flume under the conditions of the seasonal and spatial temperature variations, which have not been noticeable in designing effective marine outfall system. To predict and analyze the behaviour and dilution characteristics of plume not just with the effluent temperature, but also with the seasonal variation of temperature of surround water and tidal changes, CORMIX(Cornell Mixing Zone Expert System)-GI have been applied. The results should be used with caution in evaluation the mixing zone characteristics of discharged water. We hope to help for the effective operation of outfall system, probable outfall design, protection of water quality, and warm water discharges from a power plant, etc.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.3
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• pp.245-253
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• 2001

Mixing zone characteristics of the wastewater effluents discharged from Sokcho ocean outfall have been investigated using an outfall mixing zone model which was developed on the basis of Huang et al.'s(1996) analysis method. The model was applied to Sokcho ocean outfall case and was used to simulate the concentration distribution of wastewater effluents using winter season's data, ie. daily effluent flowrate, ocean current and density stratification data which were measure for two months in the outfall area. Hourly concentration distribution of outfall effluent discharges was calculated and they were averaged for the period of 15 days which covers the ambient flow variability of the neap and the spring tidal currents. The results show that near-field dilution was relatively high with the minimum dilution of 130 for the winter season. The mixing zone was extended to the coastal beach area rather than offshore because of major direction of coastal currents. This may cause a deteriorating impact on coastal water quality, especially to the adjacent swimming beach area.

• Water Engineering Research
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• v.4 no.2
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• pp.69-85
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• 2003

Previously developed empirical equations used to calculate the parameters of the transient storage model are analyzed in depth in order to evaluate their behavior in representing solute transport in the natural streams with storage zone. A comparative analysis of the existing theoretical and experimental equations used to predict parameters of the transient storage (TS) model is reported. New simplified equations for predicting 4 key parameters of the TS model using hydraulic data sets that are easily obtained in the natural streams are also developed. The weighted one-step Huber method, which is one of the nonlinear multi-regression methods, is applied to derive new parameters equation. These equations are proven to be superior in explaining mixing characteristics of natural streams with the transient storage zone more precisely than the other existing equations.

• Journal of Korea Foundry Society
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• v.5 no.3
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• pp.19-26
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• 1985

This study has been carried out to examine into wettability of Cu-5%Sn alloy in $Al_2O_3$, MgO, $SiO_2$ and graphite, respectively and investigated into the change in macrostructure of Cu-5%Sn alloy according to kind and mixing rate of mold-coating. The results obtained from the experiment are summerized as follows; 1. Cu Cu-5%Sn alloy, wettabilities of $Al_2O_3$ and MgO were good, on the other hand, wettabilities of $SiO_2$ and graphite were bad. 2. The fine equiaxed zone was created because of the role of $Al_2O_3$ and MgO as preferential nucleation sites. 3. Notwithstanding change of mixing rate of $SiO_2$ in mold coating the equixed zone was not created. 4. The area of equiaxed zone was varied according to mixing rate in the case of using $Al_2O_3$ and MgO in mold-coating.