• Journal of Radiation Protection and Research
• /
• v.24 no.2
• /
• pp.73-86
• /
• 1999

The ion-exchange method for the purification of primary coolant has been used broadly in PWR(pressurized water reactor)-type nuclear power plants due to its high decontamination efficiency, simple system, and easy operation. However, its non-selective removal of metal and non-radionuclides shortens its life, resulting in the generation of a large amount of waste ion-exchange resin. In this study, the feasibility of electrodeionization (EDI) was investigated for the purification of primary cooling water using synthetic solutions under various experimental conditions as an alternative method for the ion exchange. The results shows that as the feed flow-rate increased, the removal efficiency increased and the power consumption decreased. The removal rate was observed as a 1000 decontamination factor(DF) at a nearly constant level. For the synthetic solution of 3 ppm TDS (Total Dissolved Solid), the power consumption was 40.3 mWh/L at 2.0 L/min of feed flow rate. The higher removal rate of metal species and lower power consumption were obtained with greater resin volume per diluting compartment. However, the flow rate of the EDI process decreased with the elapsed time because of the hydrodynamic resistivity of resin itself and resin fouling by suspended solids. Thus, the ion-exchange resin was replaced by an ion-conducting spacer in order to overcome the drawback. The system equipped with the ion-conducting spacer resolved the problem of the decreasing flow rate but showed a lower efficiency in terms of the power consumption, the removal rate of metal species and current efficiency. In the repeated batch operation, it was found that the removal efficiency of metal species was stably maintained at DF 1000.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.7 no.2
• /
• pp.57-64
• /
• 1999

The purpose of this study is to establish effective conditions for controlling $CH_4$, $N_2O$ emission from organic Waste / wastewater treatment processes. Continuous and batch experiments were conducted to treat the micro algae from polluted and eutrophicated lakes through the thermophilic oxic process. The microalgae used were mainly Microcystis sp.(collected from eutrophic lake) and Chlorella sp. (cultured in laboratory) Wasted cooking oil was added by aid-heating source. Physico-chemical components of sludges and microalgae were analyzed. In batch experiments, air supply was changed from 50ml/min to 150ml/min. The temperature. water content and drained water were affected by the air flow rate at initial stage. However, there was almost no influence of air flow rate on them in middle and last stages. At air flow rate of 100ml/min, the degradation rate of organic material was higher than that at other air flow rates. $CO_2$ concentration in exhaust was proportional to the strength of aeration, especially at initial stage when degradation was active. $CH_4$ with low concentration was detected only at starting stage when air diffusion was not enough. $N_2O$ production was not affected by variation of air supply. In continuous experiments no matter what the dewatering methods (with PAC and without PAC) and media (wood chip and reed chip) were changed, $N_2O$ was almost not affected by variation of injected air. Result showed that the reed chips using for lake purification could be used as media for thermophilic oxic process in lake and marshes area. $CO_2$ concentration was not so much affected by the change of dewatering methods and media types. $CH_4$ was not detected in the experimental period. So it can be shown that the thermophilic oxic process had been well operated in wide handling conditions regardless of media and dewatering methods.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.6
• /
• pp.453-457
• /
• 2016

In various industrial plants such as power generation plants, petrochemical plants, and unit factories, there is an increasing demand for a system that generates hot water using waste or surplus steam. Compact steam unit (CSU), which produces hot water by using steam, is a good solution considering energy reuse. In this study, as a basic study to develop a high-pressure CSU, heat transfer characteristics of a hybrid heat exchanger were investigated through experiments, in order to use the hybrid heat exchanger instead of a conventional plate heat exchanger as the core component of CSU. The experimental results are the followings. Heat balance between the hot side and cold side was satisfied within ${\pm}5%$. Overall heat transfer coefficient increased linearly as the Reynolds number increased and exceeded $5,524W/m^2K$ when the flow velocity was above 0.5 m/s. In addition, pressure drop also increased as the Reynolds number increased, and pressure drop per unit length was below 50 kPa/m.

• The Korean Journal of Community Living Science
• /
• v.25 no.1
• /
• pp.99-111
• /
• 2014

To verify welfare needs, rural health and environmental factors were compared between agricultural and nonagricultural groups over the past 10 years. Based on a survey of rural life by the Rural Development Administration, whose sample included agricultural (72.8%) and nonagricultural (27.2%) groups, all factors were analyzed using SAS ( 9.3). For rural home heating, the use of oil boilers (77.2%-78.0%) decreased (53.0%-53.7%) over the same period, whereas that of electric boilers increased (21.9% and 13.5% for agricultural and nonagricultural groups, respectively). The joint water- supply increased, and the use of flush toilets (52.4% to 84.5% in the agricultural group and 64.6% to 81.4% in the nonagricultural group) and hot-water bathing was higher in the agricultural group (79% to 92.6%) than in the nonagricultural group (72.2% to 87.6%) at the p<0.001 level. Incineration accounted for the largest portion of household waste until 2006, when it was replaced by other treatment methods such as the pay-per-treatment option (44.4% and 68.3% in the agricultural and nonagricultural groups, respectively) (p<0.001). Garbage disposal in 2001 was mainly burial or animal feed, but separate collection increased in 2010 (42.2% and 64.3% in the agricultural and nonagricultural groups, respectively) (p<0.001). The self-perception of health was lower in the agricultural group than in the nonagricultural group (2.96 to 2.74 on a five-point scale in the agricultural group and 3.07 to 2.98 in the nonagricultural group). Drinking decreased less in the agricultural group (criteria: one point once a week,; 1.48 to 1.20) than in the nonagricultural group (1.13 to 0.80) at p<0.001, and a similar pattern was found for smoking (p<0.001). Health screening decreased in the last 10 years (scoring based one point/1-2 times per year,: 0.94 to 0.64 in the agricultural group and 1.08 to 0.69 in the nonagricultural group;p<0.01). These results indicate that various health and environmental factors were less favorable to farmers except for bathing in comparison to nonagricultural living in the same area. This suggests that people in agriculture are less likely to live and work in favorable environments than those outside the sector and thus indicates a need for more attention to the national health welfare system for farmers for systematic realization.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.13 no.3
• /
• pp.74-90
• /
• 2010

The objectives of this paper are to introduce the GIS based resource circulation information, and to identify additional(or potential) industrial symbiosis based on existing industrial symbiosis and linkage-pair of industry by material. The resource circulation information contains information of the reuse of materials, water, and energy for all manufacturing companies in Ulsan Metropolitan City. The information can further be classified into the three steps -- input information(raw materials), flow information (products), and output information (by-products). The survey data from 3,768 industries and institutions in Ulsan Metropolitan area were collected and built into the GIS to analyze the mechanism of the industrial symbiosis. The results of this study strongly suggest that there are some additional industrial symbioses using by-products(materials, steam, waste water) and further efforts should be given to make them more effective. We expect that the methodology of building the resource circulation information of this study can be helpful to other local governments that try to build similar system.

• Economic and Environmental Geology
• /
• v.38 no.3 s.172
• /
• pp.237-245
• /
• 2005

The batch tests were performed to evaluate the applicability of the permeable reactive barrier (PRB) to in-situ treatment of groundwater with high concentration of heavy metals. The lead\chates used in this study were collected from waste rock dump of the Imgy mine, and have a low pH and high metal concentration. The acidity loading was 65kg as $CaCO_3/day$, metal loading of Fe+Al+Mn was 11.6kg/day. This type of water could be treated with biological-mediated sulfate reduction using the organic carbon mixture as a reactive media. The batch tests were carried out with five mixtures that were composed with different mixing ratios of mushroom compost, pine-tree bark, and limestone cheep. Results indicated that the PRB could reduce the acidity loading $CaCO_3/day$ to 12.3kg and reduce the metal loading to 3.3kg/day. Considering about the low pH and high metal loading, the contaminated water may be ameliorated by passing it through the buffering PRB composed with inorganic carbonate materials and then through the PRB composed with the organic carbon mixture which can induce sulfate reduction.

• Journal of environmental and Sanitary engineering
• /
• v.13 no.3
• /
• pp.148-157
• /
• 1998

Leachate is a result of the percolation of precipitation, uncontrolled runoff, and irrigation water into the landfill and can also include water initially contained in the waste as well as infiltrating groundwater. Behaviour of leachate by rainfall was studied to evaluate the variation of leachate generation and contaminants by rainfall in Sudokwon Landfill from January 1998 to October 1998. The quantity of leachate generated was measured with a flow meter, and the concentrations $BOD_5$, CODcr, T-N, $NE_3-N$, SS of leachate were also measured. Principal outcome obtained in this study are as follows : the quantity of leachate generated was the highest on August, the highest leachate generation volume in this period was 11,913㎥ and the lowest was $6,261m^3$. Although the similar amount of precipitation of 80mm applied to the two samples, there were difference in leachate generation due to precipitation duration, precipitation frequency, wet condition of solid wastes. As the result of regression analysis, the correlation coefficients(r) between the quantity of leachate generated and precipitation were 0.823, 0.976 between $BOD_5$ and CODcr, 0.992 between T-N and $NE_3-N$. As the quantity of leachate generated increased 48%, the concentration of $BOD_5$ and CODcr decreased 51% and 50% respectively. Therefore it was showed that the pollutant concentrations in leachate were diluted by precipitation. The concentrations of $BOD_5$ and COBcr in the rainy season were 2000~4000mg/1, 4000~6000mg/1 respectively, and 1000~3000 mg/1, 3000~5000 mg/l in the dry season. The loading of SS, $BOD_5$, CODcr(kg/month) on July was increased by 2.9 times, 2.8 times, 2.2 times with a basis on March. Therefore countermeasure of treatment facilities according to increase of loading by rainfall in summer is necessary.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.5
• /
• pp.571-577
• /
• 2012

In this study, a small movable batch treatment system for dredging soil deposited in a rain water tube is proposed; further, a vacuum silo sorting separation device with a vacuum silo, first-stage sorting separator, and conveyor is designed. The vacuum silo sorting separation device also consists of a storage tank, transferring screw, vacuum gate, screen bar, screen bar cleaner, and vacuum discharging device. In view of the fact that the flow of drawn air in the storage tank is a major factor influencing the sorting separation performance, the optimum shape of the tank is determined by CFD flow analysis. In addition, by using CAE structure analysis, the safety of a storage tank made of boards is examined. The specifications of the vacuum silo sorting separation device are determined by conducting mechanical and dynamic simulations of the driving mechanism of the vacuum silo sorting separation device through 3D-CAD modeling. Following this study, we will design a drum-screen-type second sorter, a decanter-type dehydration device, and waste water tank and pump as a secondary device. Further, on the basis of this design, we will construct a prototype model and carry out a field test.

• Clean Technology
• /
• v.8 no.3
• /
• pp.119-128
• /
• 2002

In the present study the membrane filtration characteristics of a commercially available synthetic water-based cutting oil through two kinds of ultrafiltration membranes (HF1-45-CM50 and HF1-43-CM100) with molecular weight cut-offs of 50,000 and 100,000, respectively, have been investigated in detail. Among these membranes, the hydrophilic one (HF1-45-CM50) was found to show a satisfactory result for both the permeate flux and the permeability of oil components, whereas the permeate flux obtained with the hydrophobic membrane (HF1-43-CM100) appears to be significantly low, indicating that synthetic cutting oil was easily wetted on the hydrophobic membrane surface and induced more membrane fouling. The effect of material characteristics of the membrane on the filtration characteristics was found to be much more significant compared with the mean pore size of the membrane. Backflushing by nitrogen gas was applied to reduce the formation of a gel layer and membrane fouling. With the hydrophilic membrane, the backflushing was found to increase the permeate flux, whereas the backflushing resulted in a decrease in flux for the hydrophobic membrane. The flux recovery was observed to be highest when the membranes fouled with waste synthetic cutting oil were immersed into a cleaning solution for more than 72 hours and then backflushed by nitrogen gas.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.2
• /
• pp.145-150
• /
• 2005

An extensive numerical analysis is carried out to investigate the slope stability of the wasted mine tailing landfill constructed by the utilization of fine recycled-concrete aggregates. To do this, first, the physical and mechanical properties of the fine recycled-concrete aggregates and the wasted mine tailing are investigated, and the settlement and the change of material properly of the fine recycled-concrete aggregates resulted from reaction with water are also examined. The $OH^-$ elution from the fine recycled-concrete aggregates reacted with water slightly causes the change of material properties such as porosity, permeability and waster absorption, but the settlement does not happen noticeably. The results of numerical analysis of the landfill slope built with wasted mine tailing and recycled-concrete aggregates in alternate layer indicate that slope stability increases with decreasing the slope ratio, with decreasing the groundwater level inside slope, and with increasing the depth of fine recycled-concrete aggregate layer. Based on this study, thus, engineers working in related to the wasted mine tailing landfill design and construction using the fine recycled-concrete aggregates should be considered the slope ratio, the groundwater level, the depth of fine recycled-concrete aggregate layer.