• Journal of Korean Society of Environmental Engineers
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• v.38 no.9
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• pp.469-475
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• 2016

The study is the result of an practical operation analysis for the full scale fishery product wastewater treatment plant with immersed MBR (iMBR) process. Since fishery product industries show a wide range of wastewater generation by the season, design and operation of the equalization basin are very important factor. The aeration system for the equalization basin mixing can save the chemical consumption for followed system through the restriction of acid fermentation. The concentrations of wastewater primary DAF process treated were BOD 2,291 mg/L, $COD_{Mn}$ 530 mg/L, SS 256.8 mg/L, T-N 38 mg/L, T-P 13.5 mg/L respectively. It was considered that iMBR is the most efficient biological process for high salinity content wastewater since It is irrelevant to the capability of the sludge precipitation. SADp and SADm were 0.31, $26.5m^3/hr{\cdot}m^3$ respectively. In iMBR process, the critical F/M ratio was derived at 0.08~0.10 gBOD/gMLSS by analysing the correlations between MLSS, normalized TMP and temperature. The effluent concentrations were BOD 1.8 mg/L, $COD_{Mn}$ 12.4 mg/L, SS 1.0 mg/L, T-N 7.85 mg/L, T-P 0.1 mg/L and removal efficiencies were 99.9%, 97.6%, 96.3%, 95.7%, 97.8% respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.579-584
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• 2017

The damper oil seal of a high-speed railway vehicle is made from nitrile butadiene rubber (NBR) in order to prevent lubricant from leaking into the damper and to stop harmful contaminants from entering the external environment while in service. Oil leakage through the seal primarily occurs from fatigue failure of the damper. Cumulative damage of the seal occurs due to the contact force between the rod and the rubber during movement due to track irregularities and cants, among other factors. Thus, the design of the oil seal should minimize the maximum principal strain at weak points. In this study, the optimal cross section of the damper oil seal was found using the multi-island genetic algorithm method to improve the durability of the damper. The optimal shape of the oil seal was derived using process automation and design optimization software. Nonlinear material properties for finite element analysis (FEA) of the rubber were determined by Marlow's model. The nonlinear FEA confirmed that the maximum principal strain at the oil leakage point was decreased 24% between the initial design and the optimum design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.1-7
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• 2018

The gases emitted from internal combustion engines using fossil fuels are causing many social problems, such as environmental pollution, global warming, and adverse health effects on the human body. In recent years, the demand for renewable energy has increased, and government policy support and research and development are also active. In the collecting part of a solar energy system, which is widely used at home, propylene glycol (PG) (anti-freeze), as a heating medium, is mixed with water at a fixed value of 50%, and the heat is transferred to the collecting part at subzero temperatures. On the other hand, when leakage occurs in the heat medium in the heat collecting part, supplemental water is supplied to the solar heat collecting part due to the characteristics of the solar heat system, so that the concentration of antifreeze in the replenishing water becomes low. As a result, the temperature of the solar heat collecting part is lowered resulting in a frost wave, which causes economic damage. The purpose of this study was to develop a device capable of controlling the antifreeze concentration automatically in response to a temperature drop to prevent freezing of the heat collecting part generated in the solar energy system. The electrical conductivity of the H2O component was larger than that of PG, and the resistance increased with decreasing temperature. The PG concentration control values of 40, 50, and 60% should be controlled through calibration with a PG concentration of 39.6, 50.7, and 60.1%.

• The Korean Journal of Mycology
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• v.22 no.2
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• pp.190-195
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• 1994

Studies were conducted to determine the potential of sodium hypochlorite(SHC) on the control of bacterial yellow blotch in cultivated oyster mushroom, Pleurotus ostreatus. SHC at the concentration of 80 ppm was effective on the control of Pseudomonas agarici causing yellow blotch in oyster mushroom except number 916 isolate. In vitro the mycelial growth was slightly inhibited at the concentration higher than 100 ppm of sodium hypochlorite, but retardation of the mycelial growth was soon recovered. Spray of SHC solution at the concentration of 40-50 ppm per day significantly reduced the incidence of the yellow blotch without impairing the growth of oyster mushroom in field culture. However, the higher concentration of SHC(67 ppm) induced yellow brown or dark gray in color and deformed cap and elongated stripe in morphology of fruiting body. Results indicate that periodical spray of sodium hypochlorite seems to be the recommendable method for protection against bacterial yellow blotch disease in oyster mushroom without reducing food quality.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.671-675
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• 2012

This study was conducted to establish the BMPs (Best Management Practices) for preventing pollutant loadings from paddy rice field applied livestock liquid manure from 2008 through 2011. Cultivated paddy rice fields (Gyeonggi province, Korea) were treated with SCB (Slurry composting and bio-filtration process) liquid fertilizer. The BMPs for paddy rice field developed in this study includes: 1) the controlling a drainage water gate in paddy rice field from right after SCB liquid fertilizer application to 3 weeks after rice transplanting; 2) livestock liquid fertilizer application to paddy rice soils in 20 days before rice transplanting to encourage the utilization of liquid fertilizer; 3) preservation of surface water depth to 5 cm in a paddy field right after SCB liquid fertilizer applied to minimize a water pollution and enhance the utilization of liquid fertilizer; and 4) blocking a water gate at least for 2 days to inactivate E. coli survival. The findings of this study will provide useful and practical guideline to applicators of agricultural soil in deciding appropriate handling and time frames for preventing pollution of water quality for sustainable agriculture.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.582-588
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• 1997

Synthetic reaction of TAME, ETBE, and MTBE compounds used largely for gasoline octane number enhancer to prevent air pollution was investigated using heteropolyacid catalyst in a fixed bed flow reactor. In the synthetic reaction of TAME, ETBE and MTBE, after hetero atom being replaced with poly atom, the activity of the catalyst, $H_4SiW_{12}O_{40}$ with coordinated bond with W and an hetero atom of Si was the highest among the catalysts tested. Also the activity depended upon the metals replaced which are related to the catalyst acidity. $FeHPW_{12}O_{40}$ and $K_3PM_{o12}O_{40}$ catalysts showed high activity in TAME synthesis, while they were not effective in ETBE and MTBE synthesis. In this study catalysts showing high activity were selected and mixed with equal weight combination of $H_4SiW_{12}O_{40}$ and $Sr_2SiW_{12}O_{40}$ ;$H_4SiW_{12}O_{40}$ and $NaH_2PW_{12}O_{40}$ ; $Fe_{1.5}PW_{12}O_{40}$ and $Mg_2SiW_{12}O_{40}$ ; $Mg_2SiW_{12}O_{40}$ and $Ba_2SiW_{12}O_{40}$. The mixed heteropolyacid catalysts showed higher TBA conversion rate and better selectivity of ETBE and MTBE than the single catalysts.

• Journal of the Korea Concrete Institute
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• v.27 no.1
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• pp.65-73
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• 2015

This study discussed the pozzolanic properties of calcined sewage sludge (CSS) according to calcination and fineness conditions. The chemical and mineralogical analysis of CSS according to calcination temperature and time were carried out and compared with that of the existing pozzolanic materials such as fly-ash, blast furnance slag and meta-kaolin. Various mortars were made by mixing those CSS and $Ca(OH)_2$ (1:1 wt. %), and their compressive strength and hydrates according to experimental factors such as fineness of CSS and curing age were also investigated in detail. The results show clearly the potentiality of calcined sewage sludge (CSS) as an admixture materials in concrete, but the CSS should be controlled by calcination temperature and time, and fineness etc. In this experimental condition, the calcination temperature of $800^{\circ}C$, calcination time of 2 hours and fineness of $5,000cm^2/g$ were optimum conditions in consideration of the mechanical properties and economic efficiency of CSS. The compressive strength of CSS mortars was higher than that of fly-ash mortars and blast furnace slag mortars, especially at the early ages. Then, the utilization of CSS in construction fields was greatly expected.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.1
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• pp.99-107
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• 2001

Manufacture of fishing vessel is needed the effective material for light, strength, fire and corrosion of water in order to improve durability by high-speed and fishing. These fishing vessel can be divided into FRP and AI alloys fishing vessel. FRP fishing vessel is light and effective for strength but highly ignited and susceptible to heat during the manufacturing ship by-produce noxious component for human. In the case of a scrapped ship, it cause environmental pollution. On the other hand, aluminum is a material in return for FRP and has merit of high-strength and lightness. It's more heat proof and durable than FRP and superior to prevent from corrosion. Al alloys fishing vessel development is rising as an urgent matter. But, al alloy has some defect of bad weldability, welding transformation, cracks and overcost of construction. Therefore this study is to develop the new welding joint shape solving aluminum defects and mechanical behavior. First of all, strength was compared and reviewed by analysis of plate, stiffen plate, new model simplified by using plate theory. On the base of this result, plate and new model of temperature distribution, weld residual stress and strength of tensile, compressive force were compared and reviewed by finite element computer program has been developed to deal with heat conduction and thermal elasto plastic problem. Also, new model is proved application possibility and excellent mechanic by strength comparison is established to tensile testing result.

• Journal of the East Asian Society of Dietary Life
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• v.24 no.1
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• pp.70-79
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• 2014

This study was conducted to develop natural additive for the improvement of lipid stability and the suppression of pathogenic contamination during the storage periods of fermented sausage. Fermented sausage prepared with grapefruit extract showed good suppression of lipid oxidation and pathogenic bacterial growth, and it was higher than that of fermented sausage prepared with nitrate until 7 days of storage. Fermented sausage prepared with treatment A (sodium nitrate and L. acidophilus), B (sodium nitrate and L. brevis), C (ascorbic acid and L. brevis) and D (grapefruit extract and L. brevis) were compared. As results, treatment C and D showed the lowest pH changes among treatments, and the highest growth of lactic acid bacteria was represented in treatment D. In the suppression effect of E. coli, the bacterial count was below 100 in all treatment except the treatment A. There were no differences among treatment in the brightness of meat color (p<0.05). Treatment D showed significantly high values in the redness, but showed the lowest values in the yellowness. In sensory and texture test, treatment C and D were superior compared to others. Therefore, grapefruit was represented as a good source of antioxidant for fermented sausage, and L. brevis isolated from kimchi was effect in lowering pH value of sausage during fermentation and it was also effective to persist fermentation during storage period and to reduce the occurrence of pathogenic bacteria by the suppression of their growth.

• Journal of Food Hygiene and Safety
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• v.14 no.3
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• pp.293-304
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• 1999

The purpose of this study was to evaluate the microbiological quality, and to assure the hygienic safety of the food production in the university food service facility located in Seoul in accordance with the Hazard Analysis Critical Control Point(HACCP) concepts. In the hygienic state assessment of kitchen, it has revealed that it was very important to remove water from the kitchen floor and to establish standard method for disinfection of cooking utensils. And foodservice workers were required to have training program for the safe handling of food and utensils since they did treat food without hygienic gloves. The kitchen layout had to be improved because the near distance of table with heating unit and shelf might cause the growth of microorganisms when prepared food was kept on the shelf. In terms of the timetemperature measurement and microbiological quality assessment during each of the food production phases, most of sengchae (raw vegetable dish) and namul (cooked vegetable dish) were treated within danger zone for food safeness ($5~60^{\circ}C$). It has shown that the microbiological quality of raw materials was very much inferior at the time of receiving based on the TPC($10^{5}~10^{7}$), coliform($10^{3}~1O^{6}$), which was not acceptable level(TPC:$10^{6}$, coliform:$10^{3}$) suggested by Solberg. Microbiological growth has increased in the both of sengchae and namul considerably during most of food production phase. Therefore, it is extremely important to reduce holding and serving time and to avoid treating food within the danger zone for food safeness. In addition, the prevention of cross-contamination during mixing the ingredients with improper equipments and with insanitary treatments by workers was also important to keep the food safety in this speciqic university foodservice facility.