• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.219-222
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• 2005

Recently, the interest of the engine capacity and environment of the atmosphere is increasing, so the researches for the engine capacity have been conducted for a long time. But the internal environment of an automotive engine is very severe. A piston is exposed to combustion gas of over $2000^{\circ}C$ and strong friction is occurred by high speed motion in the cylinder. The fraction between piston and wall of the cylinder causes the increase of temperature in the engine. The temperature of the engine has an effect on the engine capacity. If the temperature is high, the capacity of the engine is low. So we have to maintain the optimum temperature. To maintain the optimum temperature, the enough flow rate of the engine oil is needed. The oil jet is used to control the flow rate of the engine oil and supply the engine oil to the piston and cylinder. The purpose of this study is to check the mass flow rate of the engine oil and the characteristics of internal flow of the oil jet. Flow pattern of the engine oil is very important because it concludes the loss in the oil jet. This study is the previous research about the oil jet and we will consider the movement of the ball check valve to get more accuracy result.

• Journal of Soil and Groundwater Environment
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• v.21 no.5
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• pp.1-7
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• 2016

The removal of non-aqueous phase liquids (NAPLs) from groundwater using pure water, via pump and treat, is quite ineffective due to their low solubility and hydrophobicity. Therefore, the objectives of pilot tests were to select potentially suitable surfactants that solubilize tetrachloroethylene (PCE) and trichloroethylene (TCE) present as contaminants and to evaluate the optimal range of process parameters that can increase the removal efficiency in surfactant-enhanced soil flushing (SESF). Used experimental method for surfactant selection was batch experiments. The surfactant solution parameters for SESF pilot tests were surfactant solution concentration, surfactant solution pH, and the flow rate of surfactant solution in the SESF pilot system. Based on the batch experiments for surfactant selection, DOSL (an anionic surfactant) was selected as a suitable surfactant that solubilizes PCE and TCE present as contaminants. The highest recovery (95%) of the contaminants was obtained using a DOSL surfactant in the batch experiments. The pilot test results revealed that the optimum conditions were achieved with a surfactant solution concentration of 4% (v/v), a surfactant solution pH of 7.5, and a flow rate of 30 L/min of surfactant solution (Lee and Woo, 2015). The maximum removal of contaminants (89%) was obtained when optimum conditions were simultaneously met in pilot-scale SESF operations. These results confirm the viability of SESF for treating PCE and TCE-contaminated groundwater.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.2
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• pp.49-59
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• 2000

Wave distribution in Jangjeon Harbour is numerically simulated for an optimum design of the harbour facilities. A deep-water design wave is estimated based on stochastic extreme wave analysis of wind data in the vicinity of the harbour, and it is applied to the boundary condition at open sea. Boussinesq wave theory that includes effects of frequency dispersion and nonlinearity is employed for the wave simulation. The porosity and sponge layer are adapted at beach to depict partial reflection and complete absorption of waves, respectively. The design wave for breakwater is computed in global domain with coarse grids and the wave distribution inside of wharf is simulated in local domain with fine grids.

• Journal of Korean Society on Water Environment
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• v.21 no.5
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• pp.448-457
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• 2005

The conventional activated sludge processes were operated as a combined organic substrate removal and nitrification. So, it was necessary to provide with oxygen for both carbon and ammonia removal. But, in the BNR processes, nitrification is separated from carbon removal that causes fast ammonia oxidation and reduced oxygen demands. And most of the substrate is utilized by denitrification organisms and phosphorus accumulating organisms. with these appearances, mathematical model for BNR processes different from IWA ASM can be simplified and applied. In this study, it was performed that the existing equations as McKinney model, nitrification model published by U.S. EPA and oxygen demands from stoichiometry and the relationship between NUR and OUR were applied to full-scale BNR processes and the results were compared with the measured. and it is possible to make out the optimum design parameter from those equations.

• The Journal of Sustainable Design and Educational Environment Research
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• v.8 no.2
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• pp.40-50
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• 2009

The toilet in school building is one of most crucial elements for the recent changing face in school design, but the number of toilets and urinals in most school may not be sufficient to meet current needs, especially in the girl's toilet rooms. This study aims to suggest a guideline in designing the toilet in school buildings and propose the optimum area and development of models. The survey for this study is conducted through questionnaires collected and research from 9 schools in Seoul. The results of this study, it is suggested that the number of toilet facilities in school buildings be required by ratio of 0.5 toilets per a class and 1.1 urinal per a class for boy. In case of girls, it is suggested that ratio of 1.6 toilets per a class. Based on the result, it also propose various unit plans for each class block with space such as rest zone, green zone, powder zone etc.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.3
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• pp.327-333
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• 1999

Determination of chloride ion in concentrated NaOH solution by capillary electrophoresis has been studied. The analysis was performed by indirect UV absorption detection using chromate buffer at 254nm. The matrix effect of the sample has been observed so that the sensitivity in strong NaOH solutaion has decreased up to 10% of that in distilled water. The pH effect of the sample on the sensitivity of CE peaks has been investigated. The method for increasing the sensitivity have been investigated and the optimum pH and concentration of the buffer were 7.5 and 10mM, respectively. A cationic surfactant cetyltrimethylammonium bromide(CTAB), was added to a buffer solution in order to reverse the electroosmotic flow(EOF) in the capillary. This results in a short analysis time and better peak shapes. Using this optimum condition, the determination of chloride ion in real environmental sample has been performed, which is captured in strong NaOH absorbent prepared for absorbing gas from chimney. The standard addition method has been applied for the quantitative analysis, and it was obtained the good reproducibility.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.2
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• pp.191-199
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• 2006

Animal feedstuff handling is one of the major fugitive dust sources in the port of Incheon. For the effective control of fugitive dusts emitting from the port of Incheon, dust control facilities with bag filter systems should be designed properly considering the characteristic of the fugitive dusts including those from animal feedstuffs. The ultimate goal of this study is thus to develop the optimum fugitive dust control system which will be applicable for the renovation of the port. As the first step to achieve this longstanding goal, filtration characteristics of soybean shell, the largest dust sources in the port, were investigated with the specially designed filter testing apparatus for this study. The variables tested for the experiments included filter materials, dust concentrations, relative humidities, and filtration velocities. Also, the filtration characteristics of the other animal feedstuffs such as sunflower seed shell, tapioca, and palm shell were investigated to determine $K_2$ as a function of filtration velocity. The information on $K_2$ will be used to design the optimum bag filter systems for animal feedstuffs handling in the port.

• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.301-306
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• 2020

We investigated the individual biosorption removal of lead, copper, and nickel ions from aqueous solutions using Chara sp. algae powder in a batch mode. The impact of several parameters, such as initial concentration of the metal ions, contacting time, sorbent dose, and pH on the removal efficiency, was investigated. The maximum removal efficiency at optimum conditions was found to be 98% for Pb(II) at pH = 4, 90% for Cu(II) at pH = 5, and 80% for Ni(II) at pH = 5. The isotherm study was done under the optimum conditions for each metal by applying the experimental results onto the well-known Freundlich and Langmuir models. The results show that the Langmuir is better in describing the isotherm adsorption of Pb(II) and Ni(II), while the Freundlich is a better fit in the case of Cu(II). Similarly, a kinetic study was performed by using the pseudo-first and second-order equations. Our results show that the pseudo-second-order is better in representing the kinetic adsorption of the three metal ions.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.E1
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• pp.12-23
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• 2008

Relationship between the optimum soil water content and clay content on soil samples from mid-latitude European forest was tested. Soil samples from 4 different experimental sites (two forest sites in the Netherlands and a Danish forest) were collected, and analyzed for the soil physical and chemical characteristics. Water retention curves for the soil samples were determined according to the standard procedure ISO 11274, and pF decreased with increase in soil water contents. NO is simultaneously produced and consumed by microbiological processes, which comprise of nitrification and denitrification. NO consumption and production rates were determined from the soil samples and compared to their corresponding water retention curves in order to find the optimum soil water content and matric potential for maximum NO release from mid-latitude soils. NO consumption rate coefficient (k) in Hollandse Hout was significantly lower than those in other soil sites. Maximum NO production was observed at an intermediate soil moisture ($0.2{\sim}0.3kg/kg$) in all the soil samples. Resulting from the NO consumption and production rates for the soils, the empirical NO fluxes of the different soils were calculated in the laboratory.

• Journal of Korean Society on Water Environment
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• v.31 no.4
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• pp.418-427
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• 2015

This study was carried out to evaluate the performance of a lab-scale novel septic tank system for improving the conventional septic tank in the developing countries of water shortages. The lab-scale novel septic tank system consists of sepetic tank, aeration tank with HBC-ring, and sand filter. Optimum HRT was reguired about 1.5days to get a total COD removal efficiency of 90%, COD, BOD and SS removal efficiency was about 70%, 60%, and 85% in sepetic tank only. The structure of sepetic tank with two stages results in the high removal efficiency of organic matter. When sepetic tank, aeration tank, and sand filter were more than HRT 1.5days, 18hrs, and 12hrs, respectively, final effluent was less than 20 mg/L of BOD, 14 mg/L of SS, so that there is a high potential of its use for reusing water in flush toilet. There is no significant effect of HRT change on nutrient removal. Total nitrogen removal efficiency was about 40%, final effluent was 30~40 mg/L of TN, total phosphorus removal efficiency was about 11~25%, final effluent was 9~12 mg/L of TP. Because there is very small amounts of organic nitrogen and phosphorus in effluent, it was possible to reuse water for agricultural use.