• Korean Journal of Organic Agriculture
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• v.20 no.4
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• pp.703-713
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• 2012

Three types of aeration system were installed in experimental liquid fertilization tanks to investigate the change of characteristics of pig slurry used as a raw material for making livestock liquid fertilizer. The aeration systems of the reaction tanks were composed of three major part: the air suppling part (blower), the air pipe part, and the air diffuser part. In the first tank (reactor A), the air was supplied from the bottom of the reaction tank through air pipe system connecting air diffuser with commercial ordinary blower. In the second tank (reactor B), the air diffuser was located 10cm above the bottom of the reactor. In the third tank (reactor C), the pure air was supplied with circulating pjg slurry. The oxygen content of pure air was about 90%. The pure air was mixed with pig slurry by mechanically in the air suppling part (blower) and the air pipe part. The agitation effect was highest in the reactor C than other reactors. The contents of SS, COD, T-N and T-P of each samples collected at middle part of all reactors were 8,500, 4,188, 694 and 422mg/L; 9,000, 4,247, 813 and 356mg/L; 8,667, 6,910, 973 and 269mg/L, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.2
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• pp.113-120
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• 2021

High voltage impulse (HVI) has been gained attention as an alternative technique that could control the CaCO₃ scale problems encountered in water main, pipe, cooling tower and heat exchanger vessels. The aim of this study was to investigate the effect of electric field (E) and contact time (t) of HVI on reduction of Ca²⁺ concentration at two different temperatures of 25℃ and 60℃. A kinetic model on the effect of E and t was investigated too. As the E and t increased, the Ca²⁺ concentration decreased more than that of the control (= no HVI). The Ca²⁺ concentration decreased up to 81% at 15 kV/cm at 60℃, which was nearly 2 times greater than the control. With these experimental data-set of reduction of Ca²⁺ concentration under different E and t, the kinetic model was developed. The relationship between E and t required to reduce the concentration of Ca²⁺ by 30% was modeled at each temperature. The empirical model equations were; E^0.83· t = 60.3 at 25℃ and E^0.08· t = 1.1 at 60℃. These equations state the products of Eⁿ and t is always constant, which means that the required contact time can be reduced in accordance with the increment of E and vice versa.

• Journal of the Korean GEO-environmental Society
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• v.11 no.5
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• pp.5-13
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• 2010

The research is intended to develop and verify a biological complex soil treatment process to treat and restore soil and groundwater which is contaminated with oil, heavy metals, and nutrients through experiments with the series of treatment process such as bioreactor, rolled pipe type of contact oxidation system(RPS), and chemical processing system. 5 microbial strains were separated and selected through experiment, whose soil purification efficiency was excellent, and it was noted that anion- and nonion-series of complex agent was most excellent as a surfactant for effectively separating oils from soils. Method to mix and apply selected microbes after treating the surfactant in the contaminated soil was most effective. The removal efficiencies of total petroleum hydrocarbon (TPH)-contaminated soil about 5,000mg/L and above 10,000mg/L were approximatly 90.0% for 28 days and 90.7% for 81 days by soil remediation system and the average removal efficiencies of BOD, $COD_{Mn}$, SS, T-N, and T-P in leachate were 90.6, 73.0, 91.9, 73.8, 65.7% by the bioreactor and RPS. The removal efficiency was above 99.0% by chemical processing system into cohesive agents.

• Progress in Superconductivity and Cryogenics
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• v.15 no.2
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• pp.1-8
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• 2013

This paper reviews the development status of magnetic refrigeration system for hydrogen liquefaction. There is no doubt that hydrogen is one of most important energy sources in the near future. In particular, liquid hydrogen can be utilized for infrastructure construction consisting of storage and transportation. Liquid hydrogen is in cryogenic temperatures and therefore high efficient liquefaction method must be studied. Magnetic refrigeration which uses the magneto-caloric effect has potential to realize not only the higher liquefaction efficiency > 50 %, but also to be environmentally friendly and cost effective. Our hydrogen magnetic refrigeration system consists of Carnot cycle for liquefaction stage and AMR (active magnetic regenerator) cycle for precooling stages. For the Carnot cycle, we develop the high efficient system > 80 % liquefaction efficiency by using the heat pipe. For the AMR cycle, we studied two kinds of displacer systems, which transferred the working fluid. We confirmed the AMR effect with the cooling temperature span of 12 K for 1.8 T of the magnetic field and 6 second of the cycle. By using the simulation, we estimate the total efficiency of the hydrogen liquefaction plant for 10 kg/day. A FOM of 0.47 is obtained in the magnetic refrigeration system operation temperature between 20 K and 77 K including LN2 work input.

• Journal of Welding and Joining
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• v.23 no.6
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• pp.61-66
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• 2005

A probabilistic approach for evaluating failure risk is suggested in this paper. Probabilistic fracture analyses were performed for a pressurized pipe of a Cr-Mo steel reflecting variation of material properties at high temperature. A crack was assumed to be located along the weld fusion line. Probability density functions of major variables were determined by statistical analyses of material creep and creep crack growth data measured by the previous experimental studies by authors. Distributions of these variables were implemented in Monte Carlo simulation of this study. As a fracture parameter for characterizing growth of a fusion line crack between two materials with different creep properties, $C_t$ normalized with $C^*$ was employed. And the elapsed time was also normalized with tT, Resultingly, failure probability as a function of operating time was evaluated fur various cases. Conventional deterministic life assessment result was turned out to be conservative compared with that of probabilistic result. Sensitivity analysis for each input variable was conducted to understand the most influencing variable to the analysis results. Internal pressure, creep crack growth coefficient and creep coefficient were more sensitive to failure probability than other variables.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.4
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• pp.398-408
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• 2009

Crude oil carriers or product oil carriers are confronted with sea pollution due to hull damage from various accidents. To reduce the oil spillage of tankers, IMO(International Maritime Organization) and OPA 90(Oil Pollution Act 1990) adopted the hull structures of double skin type. In this study, oil spillage test of the double skin tanker with 1/100 scaled model was carried out under damaged condition due to collision and grounding accidents. A new structural type of oil tanker was also tested with pipe and valve system arranged in double side and single bottom hulls. Their results were compared with that of conventional type double hull on the view point of ship safety and oil spillage.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.51-59
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• 2001

Song stream is located in the upstream of the Namhan River. Normal times, the stream flows down to the east sea through the drainage pipe but at rainy season, it flows to the Namhan River. There are large stock farm, leisure town and cultivated land in this basin. The pollutants from these contamination source cause eutrophication at lake Doam and deterioration of water quality in namdai stream. In this case, this study was carried out to evaluate water quality and environmental capacity as well as economical efficiency of each industry. The basin shape factor of subject stream was 0.315, slope is higher than usual basin. The BOD, T-N and T-P productive contamination loading from each contamination source was 2,690, 974 and 194 kg/day, respectively, and major contamination source was stock farm and cultivated land. Annual BOD, T-N, T-P distribution(median value) of Song stream showed 1.0~2.2 mg/L, 3.16~5.85 mg/L and 0.024~0.197 mg/L Doam lake showed 1.1~1.9, 2.51~3.89 and 0.042~0.114 mg/L, respectively. Being compared of water quality at main stream between past and present, it showed that the water quality has improved since last five years. BOD improvement rate was 8~50%. Run off loading of BOD, T-N, T-P was 366, 1129, 17.2 kg/day, and run off rate was 13.6%, 86.2%, 11.3% respectively. Finally, the result of productivity survey of each industry, leisure town, cultivated land and large stock farm was 118, 46, 50 billion won, per T-P 1kg productive, and productivity portion was 100, 39, 42% respectively, and the highest economical efficiency industry was leisure facilities.

• Journal of environmental and Sanitary engineering
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• v.15 no.4
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• pp.59-77
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• 2000

This study was carried out to investigate on several factors, which contaminative the water quality through the water pipe during feeding water, in 42 largescaled apart-ments(total 84 cases) and assayed the Volatile Organic Compounds(VOCs) and concen-tration of heavy metals that inflow and outflow in reservior water in Jeonnam area(Mokpo, Suncheon, Yeosu) from January 1999 to December 1999. The results obtained were summarized as follows ; 1. The quality of the water pipe composition in the order of frequency in the quality of water pipes were Copper(45.2%)> Zinc(38.9%)> Stainless steel(9.5%)> PVC(4.8%)> PM(2.4%) in observing 42 sites. All of the drain pipes were used the cast iron quality. 2. The result of certification curve from 12 items(17kind) of VOCs was $1.0-4.0{\mu{g}}/{\ell}$ range, a coefficient of correlation was shown 0.99 over. A MDL of each substance range was within $0.1-1.0{\mu{g}}/{\ell}$. 3. The result of the assay, 5 kinds(Viny chloride, Dichloromethane, Ethylbenzene, M,P-xylene, Styrene) of the VOCs of 14 kinds was not detected and the other items were detected slightly. The detection rate of one item and over in total VOCs samples, were 25.9% in inflow and 27.9% in outflow. And frequency of detect in inflow/outflow of THM(Chloroform, Bromodichloro-methane, Dibromochloromethane, Bromoform) were shown higher than 94.1%, 97.0% each stages. It comes to the conclusion that all of the samples were reason able for drinking water standards. 4. The coefficient of correlation were reasonable, it shown 0.999 over in $0.1-1.0{\mu{g}}/{\ell}$ of a measuring range conditions of 4kinds in organic substance(Zn, Cu, Fe, Mn). 5. The results were showed suitability in 78 cases(92.9%) and unsuitability in 6 cases (7.1%), in 84 cases of in organic substances. Compare to inflow stage, mean concentrations of heavy metal, were increased slightly in Zn, Cu, Fe except Mn than outflow stage. The result of the mean concentration in organic substance inflow and outflow in the apartment water tank using Pair-compared T-test, in 95% reliance index, were $0.179mg/{\ell}(0.151-0.307mg/{\ell})$ in Zinc, $0.136mg/{\ell}(0.113-0.230mg/{\ell})$ in Copper, $0.052mg/{\ell}(0.048-0.098mg/{\ell})$ in Fe, and there was a bit growing tendency but there was no differece in Mn. 6. The mean concentration of Copper which used Cu pipe as a water supply pipe in apartment were $0.216mg/{\ell}(0.161-0.338mg/{\ell})$ in case of the Zine pipe were $0.286mg/{\ell}(0.204-0.435mg/{\ell})$. It shows that the detection rate was more higher than the other material used in Cu or Zn as the water supply pipe. We supposed to Cu and Zn substance were gushing out water supply pipe.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.409-421
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• 2012

Ethanolamine (ETA) is mainly used to prevent corrosion of pipe in secondary cooling system of nuclear power plant. Condensed ETA in wastewater could increase COD and T-N when it was emitted to natural water system. Compared to conventional treatments, electrochemical oxidation process using packed bed bipolar electrodes was adopted to treat COD and T-N. According to arrangement of feeder electrode, single packed bed bipolar electrode reactor and multi-paired packed bed bipolar reactor were developed and conventional zero-valent iron (ZVI) was selected as conducting bipolar electrode. Bipolar electrodes were coordinated three-dimensionally in the reactor. The experimental results showed that COD and T-N was little removed in unit system at different pH condition (pH 8 and 11) on 100V. However, in multi-paired system that applied 600V, COD was eliminated 80.85% (anode-cathode-anode, A-C-A) and 85.11% (cathode-anode-cathode, C-A-C), respectively. T-N was also removed 96.88% (A-C-A) and 90.63% (C-A-C), simultaneously. Current efficiency was estimated both single and multi-paired system. At unit bipolar packed bed reactor, current efficiency was almost zero, however in multi-paired system, current efficiency was 300~500% at A-C-A and 250~350% at C-A-C. Current efficiency was over 100% hence it was confirmed that this system is more effective than conventional electrochemical oxidation system.

• Korean Journal of Agricultural Science
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• v.7 no.2
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• pp.103-108
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• 1980

In order to elucidate the source of bacterial contamination during processing U. H. T. milk and to ensure its hygienic control, bacterial numbers were determined each step of the processes on the milks, water, tanks and pipe lines, and environments. The results obtained were as follows. 1. The viable numbers of mesophilic bacteria were $1.2{\sim}1.9{\times}10^7/ml$ of milk in the storage tank and in pipe line connected to the preheater. These were decreased to $7.0{\times}10cells{\sim}3.4{\times}10^2cells/ml$ after preheating and homogenization, and to $1.0{\times}10cells/ml$ after sterilization, then increased up to $1.2{\times}10^2cells/ml$ after packing. 2. The numbers of thermophilic bacteria were $5.0{\times}10cells{\sim}1.0{\times}10^2cells/ml$ of milk before preheating ; $3.0{\sim}5.0{\times}10cells/ml$ after homogenization ; none in the sterilizer and surge tank ; and $1.0{\sim}8.0{\times}10cells/ml$ after packing. 3. The levels of psychrophilic bacteria were $1.0{\sim}3.7{\times}10^6cells/ml$ of milk before preheating ; $1.0{\sim}4.0{\times}10cells/ml$ after homogenization ; $1.0{\times}10cells/ml$ after sterilization ; and $2.0{\times}10cells{\sim}2.5{\times}10^2cells/ml$ after packing. 4. No coliform bacteria were detected after sterilization, while the level before preheating was $2.1{\times}10^4cells{\sim}6.5{\times}10^5cells/ml$ of milk. 5. The level of mesophiles was $3.0{\times}10cells{\sim}7.4{\times}10^2cells$ in the environmental air, water supply, and unfilled packs and bottles ; that of thermophiles $1.0{\sim}3.0{\times}10cells$ in the air and water ; that of psychrophiles $1.0{\times}10cells{\sim}1.0{\times}10^2cells$ in the air, water, packs and bottles ; however no coliform was detected.