• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.60-68
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• 2006

소수 station의 수소분리정제를 위한 compact형 PSA 공정을 연구하였다. 기존 PSA 공정의 흡착탑이 차지하는 시스템의 공간을 줄이기 위하여 하나의 흡착탑 안에 다른 흡착탑을 넣어 흡착탑이 차지하는 공간을 최소화하였으며, 흡착탑 간의 열교환이 효과적으로 일어나도록 설계하였다. 수소 혼합물에 대한 활성탄으로 충진된 dual bed에서의 수소 혼합물에 대한 흡/탈착 동특성 실험을 실시하였으며, 시간에 따른 농도와 온도의 변화를 측정하였다. 수소 혼합물로는 $H_2/CO/CH_4/CO_2$ (69:2:3:26 vol.%) 를 사용하였으며, 흡착유량은 7LPM, 흡착압력은 9atm 조건에서 운전하였다. Inner bed와 outer bed의 성능은 각각의 열전달 특성의 차이로 인하여 다르게 나타났으나, 단일탑의 동특성보다는 우수한 성능을 보이고 있었다. 따라서 개발된 dual bed는 적은 부지를 차지하면서도, 보다 우수한 수소 분리 성능을 보일 수 있는 PSA 공정에 응용될 수 있음을 확인하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.709-714
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• 2006

The propose of this study was to investigate the feasibility of using waste lime core to remove phosphorus from wastewater in continuous flow reaction. The phosphorus was found to be removed from municipal wastewater by hydroxyapatite crystallization and precipation. Waste lime core size 1, 2 showed phosphorus removal rate of about 90% during early 11 hrs of run time. In addition, breakpoint time was decreased by increased inflow rate regardless of waste lime core size.

• Ecology and Resilient Infrastructure
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• v.11 no.2
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• pp.23-34
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• 2024

Sediment, aquifer materials, surface water, and groundwater from brackish Songji lake affected by salinity of seawater, were collected and a pilot scale column experiment was conducted to simulate the nitrogen transport through the hyporheic zone. Upstream experiments of groundwater displayed that groundwater containing a small amount of salt percolated into aquifers and sediments, maintaining low dissolved oxygen concentrations. In addition, partial denitrification occurred in the aquifer due to salinity and low dissolved oxygen, resulting in the accumulation of NO₂^-. In sediments,nitrogenous compounds were reduced due to adsorption by long residence times or microbial-mediated oxidation/reduction reactions. Downstream experiments of surface water displayed that surface water from the brackish lake, containing high concentrations of dissolved oxygen and salts, infiltrated into the sediments and aquifer, supplying high dissolved oxygen concentrations. This resulted in biological nitrification in the sediments and aquifer, which reduced nitrogen-based pollutants despite the high salt concentration in the surface water. Whereas partial denitrification at low dissolved oxygen concentrations in the upwelling mixing zone was observed by salinity and accumulated NO₂^-, nitrification at high dissolved oxygen concentrations in the downwelling mixing zone was not significantly affected by salinity. These results confirm that salinity in the brackish water lake has some influence on the nitrogen behavior of the hyporheic mixing zone, although nitrogen behavior is a complex combination of factors such as DO, pH, substrate concentration, and organic matter concentration.

• Journal of Food Hygiene and Safety
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• v.38 no.6
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• pp.528-536
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• 2023

In Korea, from January 2023, the Act on Labeling and Advertising of Food was revised to reflect the use-by-date rather than the sell-by-date. Hence, the purpose of this study was to establish a system for calculating the safety factor and determining the recommended use-by-date for each food type, thereby providing a scientific basis for the recommended use-by-date labels. A safety factor calculation technique based on scientific principles was designed through literature review and simulation, and opinions were collected by conducting surveys and discussions including industry and academia, among others. The main considerations in this study were pH, Aw, sterilization, preservatives, packaging for storage improvement, storage temperature, and other external factors. A safety factor of 0.97 was exceptionally applied for frozen products and 1.0 for sterilized products. In addition, a between-sample error value of 0.08 was applied to factors related to product and experimental design. This study suggests that clearly providing a safe use-by-date will help reduce food waste and contribute to carbon neutrality.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.62-67
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• 2007

It was investigated to develop the technology for simultaneous removal of $SO_2/NO$ in flue gas using liquid homogeneous catalyst. Test was carried out using a bench scale and a pilot scale experiment. The investigation led to the following results: 1) Removal efficiency of $SO_2$ gas showed good results regardless of operating condition. Removal efficiency of NO gas, however, proportionally increased with higher packing height, lower concentration and larger injection rate of catalyst 2) The optimum design parameters for simultaneous removal of $SO_2/NO$ gas using Fe(II)-EDTA catalyst were as follow: HTU(height of transfer unit) = 0.5 m, liquid gas ratio = 20 $L/m^3$, NTU (number of transfer unit) = 3 stages, cross dimension of scrubber=0.025 $m^2$ 3) The removal efficiencies of $SO_2$ and NO were 95% and 81%, repletely. 4) The high HTU is advantageous on removal of the NO, but the excessive HTU diminishes operating efficiency. Consequently, it is important to decide the HTU of optimum.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.8
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• pp.878-883
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• 2006

Removal efficiency of As(III) was investigated with a pilot-scale filtration system packed with an equal amount(each 21.5 kg) of manganese-coated sand(MCS) in the bottom and iron-coated sand(ICS) in the top. Height and diameter of the used column was 200 cm and 15 cm, respectively. The As(III) solution was introduced into the bottom of the filtration system with a peristaltic pump at a speed of $5{\times}10^{-3}$ cm/s over 148 days. Breakthrough of total arsenic in the mid-sampling position(end of the MCS bed) and final-sampling position(end of the ICS bed) was started after 18 and 44 days, respectively, and then showed a complete breakthrough after 148 days. Although the breakthrough of total arsenic in the mid-sampling position was started after 18 days, the concentration of As(III) in this effluent was below 50 ppb up to 61 days. This result indicates that MCS has a sufficient oxidizing capacity to As(III) and can oxidize 92 mg of As(III) with 1 kg of MCS up to 61 days. When a complete breakthrough of total arsenic occurred, the removed total arsenic by MCS was calculated as 79.0 mg with 1 kg MCS. As variation of head loss is small at each sampling position over the entire reaction time, it was possible to operate the filtration system with ICS and MCS for a long time without a significant head loss.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1747-1756
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• 2000

Crab shell particles (Protunus trituberculatus) and activated carbon (Norit 0.8 SUPRA) were used as packing material in a fixed-bed column. When 1 g crab shell was added in the column packed with 10 g activated carbon. breakthrough to influent 10 mg Pb/L occurred at 1520 bed volumes. as compared to 380 bed volumes for 10 g activated carbon only. Addition of crab shell particles into activated carbon column resulted in increased uptake of lead. The dramatic improvement might be attributed to an increase in $co_3{^{2-}}$ and $OH^-$ available for the binding of lead. From the result of analyses, the major mechanism of lead removal was based on dissolution of $CaCO_3$ in the crab shell followed by precipitation of $Pb_3(CO_3)_2(OH)_{2(s)}$ on the surface of activated carbon. The lead uptake increased two fold as the influent lead concentration was increased from 10 to 50 mg/L. However, it decreased by 40% as the influent pH was lowered from 5.0 to 3.0.

• KSBB Journal
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• v.16 no.3
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• pp.281-285
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• 2001

Biofiltration of volatile organic compounds (VOCs) was performed for 80 days in a biofilter packed with peat. The empty bed residence time was 3.2 min. for a gas mixture of isoprene, dimethyl sulfide, chloroform. benzene, trichlorethylene, toluene, m0xylene, o-xylene and styrene. After 34 days of acclimatization the removal efficiency for a 83 g/㎥ gas input was 93% at $25^{circ}C$ and 73% at $45^{circ}C$, respectively. The maximum cell density at $25^{circ}C$ was 1.12$\times$10(sup)8 cells/g. Removal efficiencies of m-xylene and toluene (91%) were better than that of benzene (86%). The first quarter of the packed column removed 60% of the incoming VOCs.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.2
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• pp.53-58
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• 1999

This study was carried out evaluate to identify water quality and contamination characteristics of the shallow groundwater. and their seasonal variation in the rual area of the Yongin city. Groundwater sample were collected two times (in April and September) from a total of 19 well for domestic water supply. and surface-water samples from six locations. For cations, Ca and Mg predominated. In anion competition. the influence of Cl was obvious in the april samples. However. HCO$_3$ was a major component in the september samples. Electric conductivities and the concentrations of NO$_3$-N in groundwater samples significantly decreased from the april samples to the september samples This indicates a significant seasonal variation in the shallow groundwater composition. When the shallow aquifer is connected to the surface water. then metals sorbed on the stream sediments could occur at nearby wells through the induced recharge. Contaminants at ground surface appeared to be transported to the groundwater system infiltration during the spring melt.

• Journal of Soil and Groundwater Environment
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• v.10 no.3
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• pp.16-23
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• 2005

In order to remediate acid mine drainage (AMD) from the Jeongam coal mine, steel mill slag, cow manure and limestone were used. As a result of batch test, the proper amounts for treating 1 L of acid mine water from the mine were determined as 15 g of steel mill slag, 15 g of cow manure and 500 g of limestone. After feasibility test, remediation system was arranged in the order of steel mill slag tank combination of cow manure and limestone, precipitation tank and oxidation tank. During 54 days' operations, the pH values of the treated waters increased from 3.0 to 8.3 and 61 % of sulfate concentration in an initial water was decreased. In addition, the removal efficiencies for metals in the water were nearly 99.9% for Al, Fe, Zn and 92.6% for Mn. Thus, the combination of steel mill slag, cow manure and limestone can be used as neutralization 때d metal removal for acid mine drainage.