• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.6
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• pp.252-256
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• 2015

Nitrogen oxides ($NO_X$) was emitted from flue gas of stationary sources and exhaust gas of mobile sources, can leads to various environments problems. Selective Catalysts Reduction (SCR) is the most effective $NO_X$ removal system. Commercial $V_2O_5-WO_3/TiO_2$ catalysts, usually containing $V_2O_5$ 0.5~3 wt%, $WO_3$ 5~10 wt%, and $V_2O_5$ is active in the reduction of $NO_X$ but also in the desired oxidation of $SO_2$ to $SO_3$. To reduce the amount of vanadium, using graphene matrix supported vanadium to synthesize nanocomposite. Then, we fabricated to 1 inch honeycomb type of SCR catalysts adding graphene-vanadium nanocomposite. The chemical-physical characteristics and the catalytic activity were performed by XRD, XRF, BET and Micro-Reactor (MR). As a result, the De-NOX performance was showed, similar to the commercial catalyst activity as 77.8 % and using nanocomposite catalyst as 77.1 % at $350^{\circ}C$.

• Clean Technology
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• v.29 no.4
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• pp.313-320
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• 2023

In order to increase the usability of H₂-SCR, the NOx removal characteristics with catalyst powder of PtNi/CeO₂-W-TiO₂ using Ce as a co-catalyst was synthesized and coated on a porous metal structure (PMS) were evaluated. Catalyst powder of PtNi/CeO₂-W-TiO₂(PtNi nanoparticles onto W-TiO₂, with the incorporation of ceria (CeO₂) as a co-catalysts) was synthesized and coated onto a porous metal structure (PMS) to produce a Selective Catalytic Reduction (SCR) catalyst. H₂-SCR with CeO₂ as a co-catalyst exhibited higher NOx removal efficiency compared to H₂-SCR without CeO₂. Particularly, at a 10wt% CeO₂ loading ratio, the NOx removal efficiency was highest at 90℃. As the amount of catalyst coating on PMS increased, the NOx removal efficiency was improved below 90℃, but it was decreased above 120℃. When the space velocity was changed from 4,000 h^-1 to 20,000 h^-1, the NOx removal efficiency improved at temperatures above 120℃. It was expected that the use of the catalyst could be reduced by applying the PMS with excellent specific surface area as a support.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.18-24
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• 2018

The policy-making and technological development of eco-friendly automobiles designed to increase their supply is ongoing, but the internal combustion engine still accounts for about 95% of the automobiles in use. Also, in order to meet the stricter emission regulations of internal combustion engines based on fossil fuels, the proportion of after-treatments for vehicles and (ocean going) vessels is gradually increasing. Natural gas is a clean fuel that emits few air pollutants and has been used mainly as a fuel for city buses. In the long term, we intend to develop a new NGOC/LNT+NGCO/SCR combined system that simultaneously reduces the toxic gases, $CH_4$ and NOx, emitted from CNG buses. The objective of this study is to investigate the characteristics of $de-CH_4/NOx$ according to the ceramic and metal substrates of the SCR (Selective Catalytic Reduction) catalysts mounted downstream of the combined system. The V and Cu-SCR catalysts did not affect the $CH_4$ oxidation reaction, the two NGOC/SCR catalysts each coated with two layers began to oxidize $CH_4$ at $400^{\circ}C$, and the amount of $CH_4$ emitted was reduced to about 20% of its initial value at about $550^{\circ}C$. The two NGOC/SCR catalysts each coated with two layers showed a negative (-) NOx conversion rate above $350^{\circ}C$. The ceramic-based combined system reached LOT50 at $500^{\circ}C$, which was about 20% higher in terms of the $CH_4$ conversion rate than the metal-based combined system, showing that the combined system of NGOC/LNT+Cu-SCR is a suitable combination.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.7
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• pp.1043-1053
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• 2013

We investigated the ability of soybean curd residue (SCR) and its fermented products to inhibit obesity and improve the blood lipid profiles of obese mice fed a high-fat diet. Samples were prepared by fermenting SCR with Aspergillus oryzae var effuses KACC 44990 (ASCR), a microbe used for the fermentation of traditional Korean Meju, and with Monascus pilosus IFO 4480 (MSCR), a microbe used for the production of red rice. In addition, AMSCR, a mixture composed of equal amounts of ASCR and MSCR, was also prepared. Male mice were divided into six groups and fed with either a normal diet, a high-fat diet, or a high-fat diet supplemented with SCR, ASCR, MSCR, or AMSCR. After 8 weeks, body weight gain, serum and hepatic lipid profiles, and the activities of enzymes that generate or scavenge reactive oxygen species (ROS) were evaluated. Compared with the high-fat diet group, all the test groups showed a significant reduction in body, organ, and epididymal fat weight gain. These effects were observed with supplements in the order AMSCR>ASCR>MSCR>SCR. Similarly, supplements of test samples reduced high levels of serum and hepatic triglycerides (TG), total cholesterol, and low-density lipoprotein (LDL) cholesterol caused by hight-fat diet, while high-density lipoprotein (HDL) cholesterol was increased. Interestingly, the ability of ASCR to lower serum TG was stronger than that of MSCR, while MSCR showed a stronger hypocholesterolemic effect than ASCR. Meanwhile, AMSCR returned comprehensively serum lipid levels to normal. In addition, hepatic damage was prevented with effects in the order AMSCR>ASCR>MSCR>SCR. Hepatic ROS generating system including xanthine oxidase (XO) and ROS scavenging system including superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione S-transferase (GST) were recovered to normal level by all test diets. In conclusion, this study suggests that SCR and its fermented products can inhibit obesity and improve lipid profiles.

• YAKHAK HOEJI
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• v.46 no.1
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• pp.63-68
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• 2002

The purpose of this study was to estimate the population pharmacokinetics of clarithromycin in healthy adult Korean and to investigate the factors influencing the pharmacokinetics of clarithromycin. The population pharmacokinetic parameters of clarithromycin were calculated with the data from healthy adult Koreans. A total of 798 plasma concentrations obtained from 78 subjects after administration of a single oral dose of 250 mg or 500 mg were used for the modeling. The concentration-time data were fitted to a one-compartment open model assuming a first-order absorption and elimination with no lag time. The correlations between various factors [such as sex, age, height, weight, sect creatinine (Scr) and dose and pharmacokinetic parameters were estimated with stepwise linear recession analyses. The selected covariates were incorporated in the population model of NONMEM, and the importance of each covariate was investigated by means of backwards elimination. The apparent clearance (CL/F) was significantly correlated to Scr and sex, and the apparent volume of distribution (Vd/F) was significantly correlated to Scr and height in a nonlinear relationship. The population values of Ka was 1.8 h $r_{-1}$, CL/F was 37.71 L/hr, Vd/F was 200 L and t/ sub 1/2 / was 3.68 hrs for a male Korean with 170 m height and 1.0 mg/dL Scr.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.5
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• pp.118-124
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• 2011

To reach the Euro-6 regulations of PM and $NO_x$ for light-duty diesel vehicles, it will be necessary to apply the CDPF and the de-$NO_x$ catalyst. The described system consists of a catalytic configuration, where the CDPF is placed downstream of the diesel engine and followed by a urea injection unit and a urea-SCR catalyst. One of the advantages of this system configuration is that, in this way, the SCR catalyst is protected from PM, and both white PM and deposits become reduced. In the urea-SCR system, the injection control of reductant is the most important thing in order to have good performance of $NO_x$ reduction. The ideal ratio of $NH_3$ molecules to $NO_x$ molecules is 1:1 based on $NH_3$ consumption and having $NH_3$ available for reaction of all of the exhaust $NO_x$. However, under the too low and too high temperature condition, the $NO_x$ reduction efficiency become slower, due to temperature window of SCR catalyst. And space velocity also affects to $NO_x$ conversion efficiency. In this paper, rig-tests were performed to evaluate the effects of $NO_x$ and $NH_3$ concentrations, gas temperature and space velocity on the $NO_x$ conversion efficiency of the urea-SCR system. And vehicle test was performed to verify control strategy of reductatnt injection. The developed control strategy of reductant injection was improved over all $NO_x$ reduction efficiency and $NH_3$ consumption in urea-SCR system. Results of this paper contribute to develop urea-SCR system for light-duty vehicles to meet Euro-5 emission regulations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.397-407
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• 2017

In this study, a SCR system is employed to selectively reduce $NO_X$, which is a major cause of environmental pollution and issues in diesel engines. In particular, this paper focuses on the combination of feedforward injection strategies, depending on the NO/$NO_X$ ratio, and feedback injection control, using $NH_3$ coverage ratio, based on a SCR model. A 2.2 L passenger diesel engine, which is equipped with a diesel oxidation catalyst (DOC) and a diesel particle filter (DPF), was used in the experiments. The developed control algorithm is implemented on a real-time computer with injection control algorithm. By analyzing the $NO_X$ emission measurement, the performance of the proposed injection control algorithm is verified.

• Clean Technology
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• v.23 no.1
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• pp.64-72
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• 2017

In this study, the selective catalytic reduction (SCR) for NOx removal was investigated in the temperature range of $150{\sim}400^{\circ}C$. XRD, BET and XPS analyses to determine the structural properties and valence state characteristics of the catalyst were performed. Various ball mill method were shown to a difference in activity at a low temperature below $250^{\circ}C$. Based on the catalyst with the highest denitrification efficiency, the ball mill time was the best result at 3 h. As a result of XPS analysis, the presence of the non-stoichiometric vanadium species and the increase of the number of atoms were attributed to a positive effect in the SCR reaction. it was confirmed that the correlation between the amount of lattice oxygen and the denitrification efficiency through the $O_2$ on-off experiment, and it was in a proportional relationship to each other.

• Journal of the Korean Institute of Telematics and Electronics
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• v.14 no.1
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• pp.23-28
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• 1977

This paper describes the practical design of a SCR inverter which is suposed to be very much suitable for high frequency induction heating power source. In this design an optimum control technique was applied to maintain constant output power and constant power factor to various heating load by the use of frequency control. Some appreciable characteristics was obtained for some design guide of large ndstrial heating power sources by the test of the 3KHz, 3KW inverter which was designed in this study.

• Journal of Power System Engineering
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• v.13 no.4
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• pp.5-10
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• 2009

Urea-SCR system, the selective catalytic reduction using urea as reducing agent, is a powerful technique to reduce nitrogen oxides(NOx) emitted from diesel engines. However, a tank of urea(32.5 wt%)-water solution can be frozen in low ambient temperature levels of below $-11^{\circ}C$. The purpose of this study is to understand freezing and melting phenomena of the urea-water solution, and its can be applied to get the urea-water solution from frozen it within 5 minutes after cold start. Factors considered were the type of heater and the urea tank shape. From the results, it was found that melting volume of cartridge heater B during 5 minutes of heating period was 83ml when supplying electric power of 150W. Horizontal heater B, which was put in the narrow bottom space of the tank T1, had fast melting characteristics.