• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.446-452
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• 2009

The behavior of a one-step fixed bed reactor which directly synthesizes dimethyl ether(DME) from Natural Gas was simulated. In the reactor, the prevention of the occurrence of hot spots which can cause deactivation of catalysts is pivotal, since methanol synthesis and dehydration reaction involved in the synthesis of DME are highly exothermic. Therefore, we simulated and compared performance of the reactor with counter-current cooling and pool boiling system that can be applied to a commercial plant. As a result, we found that counter-current cooling system is more effective in terms of CO conversion and DME productivity. However, pool boiling system can operate in a small temperature gradient that can decrease problems caused by hot spot. And, the system can operate in a safer range.

• KSBB Journal
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• v.24 no.1
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• pp.47-52
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• 2009

A pilot-plant biofilter (1750 mm W ${\times}$ 2750 mm L ${\times}$ 2000 mm H) packed with polyurethane foam (20 mm W ${\times}$ 20 mm L ${\times}$ 20 mm H) was installed in an fine chemical plant emitting gas streams containing ethyl alcohol, ethyl acetate, and dichloromethane. The biofilter was successfully operated for 30 days under highly fluctuating incoming concentrations (maximum 3500 ppm) at a residence time of 36 and 60 sec. Both ethyl alcohol and ethyl acetate were removed more than 95%, but dichloromethane removal was less than 50%. Malodor was also removed more than 90% from 17 days after start up.

• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.436-441
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• 2008

This work experimentally determined the effect of operating parameters such as temperature and solid retention time (SRT) on the phosphorus removal of municipal wastewater with waste-tire media. The experiments were carried out in pilot-scale moving bed biofilm reactor filled at a 0.15 filling ratio with the media. Total phosphorus (TP) removal efficiency was $91{\pm}5$, $75{\pm}16$, and $59{\pm}14%$ at the temperature of 9~10, 10~20, and $20{\sim}26^{\circ}C$, respectively. TP removal efficiency was $71{\pm}17$, $74{\pm}16$, $74{\pm}16$, and $68{\pm}18%$ at the SRT of 3.5~5, 5~10, 10~15, and 15~20 days, respectively. At the nitrate concentration of 1~3, 3~6, and 6~9 mg/L, TP removal efficiency was $82{\pm}9$, $68{\pm}18$, $47{\pm}7%$, respectively. The concentration of total phosphorus in the effluent was $0.1{\sim}1.8(0.8{\pm}0.4)mg/L$ regardless of operating conditions, which meets Korean phosphorus limit value, 2 mg/L, for discharge into receiving waters.

• Journal of Korea Technology Innovation Society
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• v.13 no.4
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• pp.700-716
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• 2010

This paper examines the development of smelting reduction process in POSCO from 1990 to 2007 with the perspective of post catch-up technological innovation. POSCO paid attention to smelting reduction process as a sort of next-generation iron and steel technology, and implemented COREX (coal ore reduction) by the cooperation with V$\"{o}$oest. In addition to this, POSCO started to develop FINEX (fine iron ore reduction) which can use abundant powder ore, and FINEX was developed through model plant, pilot plant, demo plant, and commercial facility. POSCO came up to innovation leader beyond fast follower by securing almost technologies concerning FINEX. The case of smelting reduction process shows various characteristics including appropriate technological choice, successive scale-up, spiral development system, complementary technological cooperation, long-tenn investment, the existence of top management's leadership, and Korean government's support in early stage. This case can be interpreted as a path-revealing innovation in the middle of technological paradigm change.

• Journal of the Korean Geosynthetics Society
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• v.10 no.1
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• pp.29-36
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• 2011

The remediation efficiency of the contaminant through laboratory experiment of the pilot scale was evaluated for the influence factors in the contaminated soils for the applicability of the prefabricated vertical drain system. It was performed numerical analysis by the method that the finite element and finite differences based on the drawn result about the remediation of contaminated soils. The parametric analysis for the applied parameter value was performed. In the pilot scale remediation experiment, as a result of evaluating with the minimum limit concentration ratio, in the case of dense and loose conditon, the remediation time was much longer. And the remediation efficiency was rapidly progressed as the time was elapsed. It was analyzed that the contaminant concentration is reduced around the extraction well as the contamination remediating rate by numerical analysis result as the time was elapsed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.12
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• pp.2727-2735
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• 1997

This paper describes a new fading compensation scheme for Wireless ATM(WATM) sytem using pilot symbols. We have carried out a simulation for bit error rate(BER) and cell loss probability(CLP) to analyze the performance of a new scheme. As the resutls, BER performance we improved by means of HEC only above 3 dB of $E_{b}/N_{0}$ in AWGN, but not at all in fading environment. However, by using a new fading compenstion scheme with HEC, BER performance degraded below to 1 dB of $E_{b}/N_{0}$ in AWGN, but BER and CLP performances in WATM system were improved remarkably, and meeted at CLP performance criterion for K=10 dB rician fading. Also, code rate will be high and harware size of codec will be small by using this new scheme with HEC OR FEC.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.3
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• pp.229-236
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• 2017

In this study, a direct contact membrane module was manufactured to be used in a pilot scale membrane distillation process to treat $3m^3/day$ of the digestate produced from anaerobic digestion of livestock manure. In order to investigate the performance of the membrane module, permeate flux was measured with and without spacer inside the module under various condition of temperature difference and cross flow velocity (CFV) through the membrane surfaces. Flux recovery rate after chemical cleaning was also investigated by applying three different cleaning methods. Additionally, thermal energy consumption was theoretically simulated based on actual pilot plant operation conditions. As results, we observed flux of the module with spacer was almost similar to the theoretically predicted value because the installation of spacer reduced the channeling effect inside the module. Under the same operating condition, the permeate flux also increased with increasing temperature difference and CFV. As a result of chemical in-line cleaning using NaOCl and citric acid for the fouled membranes, the recovery rate was 83.7% compared to the initial flux when NaOCl was used alone, and 87% recovery rate was observed when only citric acid was used. However, in the case of using only citric acid, the permeate flux was decreased at a rapid rate. It seemed that a cleaning by NaOCl was more effective to recover the flux of membrane contaminated by the organic matter as compared to a cleaning by citric acid. The total heat energy consumption increased with increasing CFV and temperature difference across the membrane. Thus, further studies should be intensively conducted to obtain a high permeate flux while keeping the energy consumption to a minimum for a practical application of membrane distillation process to treat wastewater.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.546-556
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• 2006

The purpose of this study is to improve the polluted stream water quality by pilot-scale five different constructed wetlands (CWs). Cell 1 to 3 are newly designed 2SFCW (Surface-subsurface flow CW) with 1 to 3 flow shifters (FS) in the middle of the wetland system. Cell 4 and 5 are control CW (CCW), but Cell 5 is the same type as Cell 3. The FS, which converts the route of surface and subsurface flow between two wetlands connected in series, was able to enhance the treatability of TN via nitrification and denitrification and of SS due to filtration and sedimentation. The void fraction and dispersion number of Cell 1, 2 and 3 obtained from the RTD analysis were found to be 0.73 and 0.17, respectively. COD and TP removal efficiencies of Cell 1 to 3 were similar to that of Cell 4 and 5. SS removal efficiencies of Cell 1 to 3 and 5 with FS were 5-10% higher than that of Cell 4 without FS. TN removal efficiencies of Cell 1 to 3 were 3-14% higher than that of Cell 4 and 5. The average $R^2$ values of COD, SS, TN and TP obtained from nonlinear regression analysis were similar to the results of other researchers.

• Korean Journal of Food Science and Technology
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• v.49 no.4
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• pp.408-414
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• 2017

Effects of pulsed electric field (PEF) processing on growth inhibition of indigenous aerobic microorganisms and the quality of mandarin and carrot juices were investigated. Mandarin juice was PEF-treated at 15-23 kV/cm for $23-241{\mu}s$, whereas carrot juice was treated at 13-14 kV/cm for 127-198 s. At $25^{\circ}C$ (inlet temperature), PEF treatments at 23 kV/cm for $104{\mu}s$ and 14 kV/cm for $198{\mu}s$ reduced the numbers of total mesophilic aerobes by $6.3{\pm}0.8$ and $5.5{\pm}0.9{\log}\;CFU/mL$ in mandarin juice and carrot juice, respectively. Elevation of inlet temperature to $40^{\circ}C$ increased the reduction rates in both juices. In general, the treatments resulting in the highest microbial inhibition at 25 and $40^{\circ}C$ did not alter the physicochemical and nutritional properties of both juices (p>0.05). PEF is a feasible technology to pasteurize mandarin and carrot juices commercially, with minimal quality deterioration.

• Journal of the Korean Applied Science and Technology
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• v.38 no.4
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• pp.1010-1019
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• 2021

Petroleum oil in reservoir has been acquired by primary, secondary and tertiary oil recoveries. Microbial enhanced oil recovery (MEOR) classified to tertiary oil recovery has been evaluated in two ways of in-situ and ex-situ options. In-situ MEOR injects microbes into a depleted oil reservoir and stimulates those to generate metabolites. Among metabolites, biosurfactants play an important role to make heavy residues flow. Ex-situ MEOR injects microbial metabolites instead of microbes into a reservoir to recover oil. Even though both in-situ MEOR and ex-situ MEOR are eco-friend processes, in-situ MEOR can be preferred because it is more economic. Even though MEOR have been evaluated for a long time, it is still in the state of evaluating in a pilot-scale. Among microbes, bacteria have been widely evaluated in MEOR purpose. In this paper, bacteria for MEOR were summarized and their metabolites were qualitatively evaluated.