• Journal of Korean Society of Water and Wastewater
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• v.31 no.4
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• pp.339-346
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• 2017

In this study, thermal performance test of VMD module was performed, prior to the construction of the demonstration plant using the vacuum membrane distillation (VMD) module of the capacity of $400m^3/day$ and to the commercialization of the VMD module. For the thermal performance test, the experimental equipment of capacity of $2m^3/day$ was constructed. The permeate flux test and thermal performance test according to feed water conditions such as temperature and flow rate were conducted. The VMD module used in the study was manufactured by ECONITY Co., LTD with PVDF hollow fiber membrane. As a result, the Performance Ratio (PR) of the VMD module showed the maximum value of 0.904 under the condition of feed water temperature of $75^{\circ}C$ and flow rate of $8m^3/h$. PR value of the VMD module using PVDF hollow fiber membrane showed linearly increasing relationship with feed water temperature and flow rate. Also, The permeate flux of the VMD module was analyzed to have maximum value of 18.25 LMH and the salt rejection was 99.99%.

• Proceedings of the Membrane Society of Korea Conference
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• 2005.11a
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• pp.133-147
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• 2005

In order to investigate applicability for 2,2,2-trifluoroethyl methacrylate (TFEMA) produced by esterification of 2,2,2-trifluoroethanol(TFEA) and methacrylic acid(MA) using pervaporation membrane, poly(vinyl alcohol) (PVA) composite membranes were prepared with glutaraldehyde(GA) onto porous polyethersulfone(PES) support. The degree of crosslinking and thickness of PVA coating layer were analyzed by swelling test and SEM(scanning electron microscopy), respectively. Pervaporation test was done with two feed mixures; TFEA/water, MA/water. The pervaporation data were obtained as a function of content of crosslinking agent, feed composition, and operating temperature, respectively. In case of TFEA-water(90/10 wt%) feed mixture at $80^{\circ}C$, the optimized membrane showed the high permeation flux of 1.5 $kg/m^2hr$ and separation factor of 320. In case of MA-water(90/10 wt%) feed mixture, the membranealso showed high permeation flux of 2.3 $kg/m^2hr$ and separation factor of 740 in same conditions.

• Journal of Veterinary Clinics
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• v.15 no.1
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• pp.156-161
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• 1998

This study investigated the microbiological changes and distribution of bacteria producing enzyme in order to change food wastes to animal feed during 6 days at room temperature. Food wastes were divided as follows: one is untreated food wastes containing 80% water content and another wastes containing 40% water content adiusted by wheat bran. During the fermentation of food wastes, Lactobacillus sp. and Streptococcus sp. were grown the top position among investigated microorganisms in both of food wastes. Numbers of total microorganisms were much more than untreated wastes during fermentation of flood wastes with 40% water content. But, Streptococcus sp. and Enterobacteriaceae from 4 to 6 days were not detected in treated wastes with 40% water contents. This fact indicated that the adiustment of water content in food waste was effective in fermentation. However, the numbers of microorganisms producing pretense were low in both treated and untreated food wastes. These results suggested that flood wastes should be treated as food wastes with 40% water content to maintain a lot of fermentative microorganisms such as Lactobacillus sp., Streptococcus sp. and yeasts together with pretense to make final animal feed.

• Membrane and Water Treatment
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• v.8 no.2
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• pp.125-136
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• 2017

Reverse osmosis technology is being used on large scale for treatment of ground water, brackish water, wastewater and sea water. The most challenging issue in RO process is carbonate scaling which is directly linked with the efficiency and economy. Considering the natural phenomena of carbonate scaling different adaptations have been made to control scaling on the surface of RO membrane including acid dosage and antiscalant addition. As carbonate scaling is directly related with pH level of feed water, present study describes an experimental approach to reduce scaling on RO membrane by lowering the feed water pH by purging $CO_2$. In this comparative study four different conditions including control process (without any scale inhibitor), with dosage of antiscalant, with purging of $CO_2$ and with co addition of antiscalant and $CO_2$ in a feed stream line; it was established that $CO_2$ is a better appliance to reduce carbonate scaling on the membrane surface by reduce pH of feed stream. It was also observed that $CO_2$ and antiscalant mutually function better for scale control.

• Water Engineering Research
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• v.4 no.1
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• pp.1-17
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• 2003

A mathematical model was developed to simulate the performance of a prototype wind-powered reverse osmosis desalination system. The model consists of two sub-models operated in a series. The first sub-model is the wind-energy conversion sub-model, which has wind energy and feed water as its input and pressurized feed water as its output. The second sub-model is a reverse osmosis (RO) process sub-model, with pressurized feed water as its input and the flow and salinity of the product water or permeate as its output. Model coefficients were determined based on field experiments of a prototype wind powered RO desalination system of the University of Hawaii, from June to December 2001. The mathematical model developed by this study predicts the performance of wind-powered RO desalination systems under different design conditions. The system optimization is achieved using a linear programming approach. Based on the results of system optimization, a design guide is prepared, which can be used by both manufacturer and end-user of the wind-driven reverse osmosis system.

• Membrane and Water Treatment
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• v.13 no.4
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• pp.201-208
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• 2022

Emulsion Liquid Membrane (ELM) is a prominent technique for the separation of heavy metal ions from wastewater due to the fast extraction and is a single-stage operation of stripping-extraction. The selection of the components (Surfactant and Carrier) of ELM is a very significant step for its preparation. In the ELM technique, the primary water- in-oil (W/O) emulsion is emulsified in water to produce water-in-oil-in-water (W/O/W) emulsion. The water in oil emulsion was prepared by mixing the membrane phase and internal phase. To prepare the membrane phase, the extractant D2EHPA (di-2-ethylhexylphosphoric acid) was used as a mobile carrier, Span-80 as a surfactant, and Paraffin as a diluent. Moreover, the internal (receiving) phase was prepared by dissolving sulphuric acid in water. Di-(2- ethylhexyl) phosphoric acid such as surfactant concentration, carrier concentration, sulphuric acid concentration in the receiving (internal) phase, agitation time (emulsion phase and feed phase), the volume ratio of the membrane phase to the receiving phase, the volume ratio of the external feed phase to the primary water-in-oil emulsion and pH of feed were studied on the percentage extraction of metal ions at 20℃. The results show that it is possible to remove 78% for As(V), 98% for Cd(II), and 99% for Pb(II). Emulsion Liquid Membrane (ELM) is a well-known technique for separating heavy metal ions from wastewater due to the fast extraction and is a single-stage operation of stripping-extraction. The selection of ELM components (Surfactant and Carrier) is a very significant step in its preparation. In the ELM technique, the primary water-in-oil (W/O) emulsion is emulsified to produce water-in-oil-in-water (W/O/W) emulsion. The water in the oil emulsion was prepared by mixing the membrane and internal phases. The extractant D2EHPA (di-2-ethylhexylphosphoric acid) was used as a mobile carrier, Span-80 as a surfactant, and Paraffin as a diluent. Moreover, the internal (receiving) phase was prepared by dissolving sulphuric acid in water. Di-(2-ethylhexyl) phosphoric acid such as surfactant concentration, carrier concentration, sulphuric acid concentration in the receiving (internal) phase, agitation time (emulsion phase and feed phase), the volume ratio of the membrane phase to the receiving phase, the volume ratio of the external feed phase to the primary water-in-oil emulsion and pH of feed were studied on the percentage extraction of metal ions at 20℃. The results show that it is possible to remove 78% for As(V), 98% for Cd(II), and 99% for Pb(II).

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.6
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• pp.825-833
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• 2011

Forty-five Hisex commercial layers and forty-five local Saudi breed layers were used to determine the acceptable limit of short-term water restriction in the late phase of production, when the problem of high feed and water consumption is expected. The experiment was performed under hot and arid environmental conditions when the layers were at fifty weeks of age. Layers from each breed were randomly assigned in groups of five into nine floor pens. The average environmental temperature was 37.2-$38.6^{\circ}C$, and the relative humidity was between 20 to 37%. The trial was divided into 3 periods; control (1 week), water restriction (2 weeks) and rehydration (1 week). During the restriction period, layers from each breed were divided into three groups that received 20, 40, and 0% restriction of drinking water relative to their consumed water during the control period. During the study, feed and water consumption, body weight, changes in body weight, egg production, primary antibody response to SRBC, and rectal temperature were evaluated. Water restriction did not result in any clear effect on feed intake in either breed, however, commercial layers tended to consume less feed compared to the local breed. Body weight declined with water restriction during the first week of restriction in the commercial breed regardless of rate of restriction, but it was delayed until the second week in the local breed. Water restriction of 40% decreased egg production in both breeds but with a delay of 1 week in the local breed. Antibody level to SRBC was not affected by water restriction in the commercial line while it was highly affected in the local breed. A water restriction of 20% is considered to be an acceptable limit under the current experimental conditions without a negative effect on egg production in both breeds and considering the immune status of the local breed. Whereas, 40% restriction had a negative effect on egg production, and varied effects in the other traits in both breeds.

• Proceedings of the Korean Fiber Society Conference
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• 1994.10a
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• pp.137-138
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• 1994

Anionic water dispersible copolyesters were synthesized and characterized. Viscosity of the copolyester is lower than that of routine acrylic water dispersible polymers. Adhesive force of the copolyester was much higher than that of water dispersible acrylic polymers. Particle size of the copolyesters in water decreased with the increase of DMS or DEG feed ratio. With the conclusive study of the data of particle size and potential, it was found that the dispersion stability of copolyesters in water increased with the increase of DMS or DEG feed ratio. Judging from the results of potential and particle size of copolyesters, there seems to be competition between two dispersion stability factors, i.e. electrostatic stabilization and steric stabilization and as a result, morphological change of particles occurrs. Tg decreased with the increase of DEG molar feed ratio or oil contents.

• Journal of Advanced Research in Ocean Engineering
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• v.2 no.3
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• pp.136-149
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• 2016

Green water impact occurs frequently on offshore platform due to waves with a height greater relative to the freeboard of the structure. This phenomenon exerts a large impact load on the deck. In this paper, offshore platform models with green water protectors of various shapes were fixed to the center of a 3D wave tank to measure the impact pressure acting on the various points on deck and protectors. The impact pressure distribution differed depending on the protector shape, and various patterns of wave creeping up the protector were observed. The protector shape that exerted the lowest pressure impact on the deck will be useful in the deck design of offshore platform, and the model test results will be expected to be used for designers to select the best protector form.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.849-859
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• 2022

Feed-water valves (FWVs) are used to regulate the flow rate of water entering steam generators, which are very important devices in nuclear power plants. Due to the working environment of relatively high pressure and temperature, there is strength failure problem of valve body in some cases. Based on the thermo-fluid-solid coupling model, the valve body stress of the feed-water valve in the opening process is investigated. The flow field characteristics inside the valve and temperature change of the valve body with time are studied. The stress analysis of the valve body is carried out considering mechanical stress and thermal stress comprehensively. The results show that the area with relatively high-velocity area moves gradually from the bottom of the cross section to the top of the cross section with the increase of the opening degree. The whole valve body reaches the same temperature of 250 ℃ at the time of 1894 s. The maximum stress of the valve body meets the design requirements by stress assessment. This work can be referred for the design of FWVs and other similar valves.