• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.344-354
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• 2004

A pilot study was performed from September 2000 to April 2004 to examine the feasibility of the wetland-pond system for the agricultural reuse of reclaimed water. The wetland system was a subsurface flow type, with a hydraulic residence time of 3.5 days, and the subsequent pond was 8 $m^3$ in volume (2 m ${\times}$ 2 m ${\times}$ 2 m) and operated with intermittent-discharge and continuous flow types. The wetland system was effective in treating the sewage; median removal efficiencies of $BOD_5$ and TSS were above 70.0%, with mean effluent concentrations of 27.1 and 16.8 mg $L^{-1}$, respectively, for these constituents. However, they did often exceed the effluent water quality standards of 20 mg $L^{-1}$. Removal of T-N and T-P was relatively less effective and mean effluent concentrations were approximately 103.2 and 7.2 mg $L^{-1}$, respectively. The wetland system demonstrated high removal rate (92 ${\sim}$ 90%) of microorganisms, but effluent concentrations were in the range of 300 ${\sim}$ 16,000 MPN 100 $mL^{-1}$ which is still high for agricultural reuse. The subsequent pond system provided further treatment of the wetland effluent, and especially additional microorganisms removal in addition to wetland-pond system could reduce the mean concentration to 1,000 MPN 100 $mL^{-1}$ from about $10^5$ MPN 100 $mL^{-1}$ of wetland influent. Other parameters in the pond system showed seasonal variation, and the upper layer of the pond water column became remarkably clear immediately after ice melt. Overall, the wetland system was found to be adequate for treating sewage with stable removal efficiency, and the subsequent pond was effective for further polishing. This study concerned agricultural reuse of reclaimed water using natural systems. Considering stable performance and effective removal of bacterial indicators as well as other water quality parameters, low maintenance, and cost-effectiveness, wetland- pond system was thought to be an effective and feasible alternative for agricultural reuse of reclaimed water in rural area.

• Journal of Environmental Science International
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• v.15 no.6
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• pp.571-577
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• 2006

This study make a comparison between the phosphorus removal performance of FNR(Ferrous Nutrient Removal) process and A/O process by the laboratory experiments. For simultaneous removal of phosphorus, iron electrolysis was combined with oxic tank. Iron precipitation reactor on the electrochemical behaviors of phosphorus in the iron bed. The phosphorus removal in FNR process was more than A/O process. Iron salts produced by iron electrolysis might help to remove COD and nitrogen. And the demanded longer SRT is the more removes the removes COD, nitrogen, and phosphorus. Also, FNR process of sludge quantity more reduce than A/O process to input cohesive agents.

• Journal of Environmental Health Sciences
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• v.32 no.1 s.88
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• pp.27-35
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• 2006

This study was carried out to investigate the removal of nitrogen and phosphorus in municipal sewage depending on existence of biological coated media in BCM reactor. The reactor with biological coated media is the process combining $A_2/O$ process. The removal efficiencies for $COD_{Mn},\; BOD_5,\;SS$, T-N and T-P were $78\%,\;90.5\%,\;92.3\%,\;61.9\%,\;60.2\%$, respectively. The specific nitrification rate$(mgNO_3-N/gMLSS{\cdot}d)$ of Contact aeration basin was 52.2 and the specific denitrification rate$(mgNO_3N/gMLSS{\cdot}d)$ in anoxic basin was 95.1. Also, phosphorus release$(mgPO_4-P/gMLSS{\cdot}d)$ in Anaerobic basin was 71.8 and Phosphorus uptake$(mgPO_4-P/gMLSS{\cdot}d)$ in contact aeration was 27.1.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.3
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• pp.305-314
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• 2014

A pilot plant (Q=5 $m^3/d$) study was implemented for small and medium sized personal wastewater treatment plant effluent to evaluate MBR and A/O processes utilizing self-sufficient energy composed of wind and solar energy. The removal efficiencies of BOD, SS, turbidity and color were sufficient for legal water quality standards for gray water. However, those of nitrogen and phosphorus could not meet legal regulations which suggested that further removal of those contaminants were needed for reuse of the treated water. Self-sufficient energy rate was 100 % for the pilot plant due to excessive design capacity. In this research, wind and solar energy system was applied considering geological characteristics, which significantly improved energy self-sufficiency. Substantial improvement on energy self-sufficiency can be obtained by optimized investment and operation at a full scale wastewater treatment plant.

• Proceedings of the SAREK Conference
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• 2004.11a
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• pp.130-130
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• 2004

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.251-255
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• 2008

Flow field around helicopter involves incompressible flow near the blade root and compressible flow at the blade tip. A problem occurs for low Mach number flow due to the stiffness of the governing equations. Time-derivative preconditioning techniques have been incorporated to reduce the stiffness that occurs at low speed region. The preconditioned form of the compressible Navier-Stokes and Euler equations is used. Computations are performed for the Caradonna-Tung's hovering and non-lifting forward flight case. Computational results are in good agreement with the experimental data.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.251-255
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• 2008

Flow field around helicopter involves incompressible flow near the blade root and compressible flow at the blade tip. A problem occurs for low Mach number flow due to the stiffness of the governing equations. Time-derivative preconditioning techniques have been incorporated to reduce the stiffness that occurs at low speed region. The preconditioned form of the compressible Navier-Stokes and Euler equations is used. Computations are performed for the Caradonna-Tung's hovering and non-lifting forward flight case. Computational results are in good agreement with the experimental data.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.335-338
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• 2002

방사성폐기물처분연구의 일환으로 화강암지역내 심부지하수에 대한 지화학특성조사가 수행되었다. 지하수 시료는 다중패커시스템이 설치된 심부시추공으로부터 심도별로 채취되었으며, 계속적인 지화학 및 동위원소에 대한 모니터링이 진행되고 있다. 심부지하수는 pH가 약10.0이며 Na-HCO$_3$형으로 지화학적으로 특징되며, 지표로 250m이하의 심도에서는 거의 동일한 지화학적 특성을 보인다. 동위원소결과는 심부지하수는 천수기원임을 보이며, 천부지하수에 비해 약500~1,000m 높은 고도에서 함양되었음을 보여준다. 250m이하의 심부지하수는 50년이상의 체류시간을 갖음을 나타낸다.

• Journal of Power System Engineering
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• v.14 no.3
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• pp.19-24
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• 2010

The purpose of this study is to develop a snow melting system using the pulsating heat pipe(PHP). The experimental apparatus is consisted of a PHP, a concrete structure, a constant water thermostatic bath and a flowmeter. The experiment was performed at the outdoor air temperature of $-8^{\circ}C$ and inlet temperature of hot water of $75^{\circ}C$. PHP is the closed and non-loop type heat exchanger which is charging R-410A as an operating fluid. As experimental results, the temperature profile of vertical and horizontal orientation of concrete structure was measured with operating time. The heat flux of the snow melting was required more than 300 $W/m^2$. We confirmed that the snow melting system using the PHP was useful for anti-freezing road.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.6
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• pp.807-813
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• 2004

Wastewater was treated by two different treatment processes; activated sludge process and advanced wastewater treatment process (KNR process) using lab-scale experiment. Two treated wastewater showed good treatment efficiency of organic matter removal, up to 90% removal. Nitrogen and phosphorus were not effectively removed though activated sludge process, while KNR process showed good removal efficiency of nitrogen and phosphorus; 56% nitrogen removal and 95% phosphorus removal. KNR process showed better removal efficiency of organic matter, nitrogen, and phosphorus compared to activated sludge process. Organic matter characterization was tracked though measurement of UV scan, SUVA, and XAD fractionation. Treated wastewater showed higher SUVA value than wastewater influent, indicting less aromatic characteristic of organic matter. XAD fractionation showed hydrophilic fraction decreased though wastewater treatment, suggesting microbes preferentially digest hydrophilic and aliphatic molecules rather than hydrophobic and aromatic molecules of organic matter.