• Korean Chemical Engineering Research
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• 제48권2호
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• pp.147-156
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• 2010

There are four key factors for gas-phase biofilters; biocatalysts(microorganisms), packing materials, design/operating techniques, and diagnosis/management techniques. Biofilter performance is significantly affected by microbial community structures as well as loading conditions. The microbial studies on biofilters are mostly performed on basis of culture-dependent methods. Recently, advanced methods have been proposed to characterize the microbial community structure in environmental samples. In this study, the physiological, biochemical and molecular methods for profiling microbial communities are reviewed, and their applicability to biofilters is discussed. Community-level physiological profile is based on the utilization capability of carbon substrate by heterotrophic community in environmental samples. Phospholipid fatty acid analysis method is based on the variability of fatty acids present in cell membranes of different microorganisms. Molecular methods using DNA directly extracted from environmental samples can be divided into "partial community DNA analysis" and "whole community DNA analysis" approaches. The former approaches consist in the analysis of PCR-amplified sequence, the genes of ribosomal operon are the most commonly used sequences. These methods include PCR fragment cloning and genetic fingerprinting such as denaturing gradient gel electrophoresis, terminal-restriction fragment length polymorphism, ribosomal intergenic spacer analysis, and random amplified polymorphic DNA. The whole community DNA analysis methods are total genomic cross-DNA hybridization, thermal denaturation and reassociation of whole extracted DNA and extracted whole DNA fractionation using density gradient.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.281-290
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• 2018

As the internal combustion engine vehicles of high fuel efficiency and low emission are demanded, it becomes important to procure technologies for improving low-temperature performance of automotive catalyst systems. In this study, we showed that the combustion rate of diesel particulate matter is greatly enhanced at low temperature by applying fuel-borne catalyst and perovskite catalyst concurrently. It was tried to examine the correlation between elemental composition of perovskite catalyst and combustion activity of mixed catalyst system. To achieve this goal, we applied temperature-programmed oxidation technique in testing the combustion behavior of perovskite-mixed particulate matter bed which contained the element of fuel-borne catalyst or not. We tried to explain the synergetic action of two catalyst components by comparing the trends of concentrations of carbon dioxide and nitrogen oxide in temperature-programmed oxidation results.

• Journal of the Institute of Convergence Signal Processing
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• 제15권1호
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• pp.15-22
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• 2014

This paper presents the implementation of a control system of pellet boiler using wood pellet as carbon neutral material. The system also has the additional features to provide remote controlling and monitoring based on home networking technology through either public switched telephone networks or mobile communication networks. It consists of three kinds of sub-modules; a main controller provides basic and additional features such as a setting of temperature, a supplying of wood pellet, a controlling of ignition and fire-power, and a removing of soot. The second is temperature controller of individual rooms which is connected to the main controller through RS-485 links. And interface modules with PSTN and mobile networks can support remote controlling and monitoring the functions. The test results under the heating area of $172m^2$ show a thermal efficiency of 93.6%, a heating power of 20,640kcal/hr, and a fuel consumption of 5.54kg/hr. These results are superior to those of the conventional pellet boilers. In order to obtain the such high performance, we newly applied a 3-step ignition flow, a flame detection by $C_dS$ sensor, and a fire-power control by fine controlling of shutter to our pellet boiler.

• Journal of Sensor Science and Technology
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• 제14권2호
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• pp.69-77
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• 2005

The electronic nose (e-nose) has been used in food industry and quality controls in plastic packaging. Recently it finds its applications in medical diagnosis, specifically on detection of diabetes, pulmonary or gastrointestinal problem, or infections by examining odors in the breath or tissues with its odor characterizing ability. Moreover, the use of portable e-nose enables the on-site measurements and analysis of vapors without extra gas-sampling units. This is expected to widen the application of the e-nose in various fields including point-of-care-test or e-health. In this study, a PDA-based portable e-nose was developed using micro-machined gas sensor array and miniaturized electronic interfaces. The rich capacities of the PDA in its computing power and various interfaces are expected to provide the rapid and application specific development of the diagnostic devices, and easy connection to other facilities through information technology (IT) infra. For performance verification of the developed portable e-nose system, Six different vapors were measured using the system. Seven different carbon-black polymer composites were used for the sensor array. The results showed the reproducibility of the measured data and the distinguishable patterns between the vapor species. Additionally, the application of two typical pattern recognition algorithms verified the possibility of the automatic vapor recognition from the portable measurements. These validated the portable e-nose based on PDA developed in this study.

• ALGAE
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• 제32권1호
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• pp.57-66
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• 2017

The red alga Gracilaria vermiculophylla, a species native to the waters of Korea and Japan, has invaded marine coastal areas of Europe and the Americas, thriving in conditions that differ from those of its native habitat. In recent years, G. vermiculophylla has been discovered in the Long Island Sound (LIS) estuary growing alongside the native congener Gracilaria tikvahiae. The goal of this study was to determine whether the two strains of G. vermiculophylla from different regions of the world have evolved genetic differences (i.e., ecotypic differentiation) or if the physiological performance of the strains simply reflects phenotypic plasticity. Two strains of G. vermiculophylla (isolated in Korea and LIS) and a strain of the LIS native G. tikvahiae were grown for four weeks under temperatures ranging from 20 to $34^{\circ}C$ using a temperature gradient table (all other environmental conditions were kept constant). At the end of each week, wet weight of each sample was recorded, and thalli were reduced to the original stocking density of $1gL^{-1}$ (excess biomass was preserved for tissue carbon and nitrogen analysis). Generally, the growth rates of Korean G. vermiculophylla > LIS G. vermiculophylla > G. tikvahiae. After one week of growth G. tikvahiae grew 9.1, 12.0, 9.4, and 0.2% $d^{-1}$, at temperatures of 20, 24, 29, and $34^{\circ}C$, respectively, while G. vermiculophylla (LIS) grew 6.6, 6.2, 5.7, and 3.6% $d^{-1}$. G. vermiculophylla (Korea) grew 15.4, 22.9, 23.2, and 10.1% $d^{-1}$, much higher than the two strains currently inhabiting the LIS. On average, the LIS G. vermiculophylla strain contained 4-5% DW N, while the Korean strain and G. tikvahiae had more modest levels of 2-3% N DW. However, tissue N content declined as temperature increased in LIS and Korean G. vermiculophylla. The non-native haplotype may have evolved genetic differences resulting in lower growth capacity while concentrating significantly more nitrogen, giving the non-native a competitive advantage.

• Applied Chemistry for Engineering
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• 제25권1호
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• pp.1-13
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• 2014

Lithium ion batteries (LIBs) are the state-of-the-art technology among electrochemical energy storage and conversion cells, and are still considered the most attractive class of battery in the future due to their high specific energy density, high efficiency, and long cycle life. Rapid development of power-hungry commercial electronics and large-scale energy storage applications (e.g. off-peak electrical energy storage), however, requires novel anode materials that have higher energy densities to replace conventional graphite electrodes. Germanium (Ge) and silicon (Si) are thought to be ideal prospect candidates for next generation LIB anodes due to their extremely high theoretical energy capacities. For instance, Ge offers relatively lower volume change during cycling, better Li insertion/extraction kinetics, and higher electronic conductivity than Si. In this focused review, we briefly describe the basic concepts of LIBs and then look at the characteristics of ideal anode materials that can provide greatly improved electrochemical performance, including high capacity, better cycling behavior, and rate capability. We then discuss how, in the future, Ge anode materials (Ge and Ge oxides, Ge-carbon composites, and other Ge-based composites) could increase the capacity of today's Li batteries. In recent years, considerable efforts have been made to fulfill the requirements of excellent anode materials, especially using these materials at the nanoscale. This article shall serve as a handy reference, as well as starting point, for future research related to high capacity LIB anodes, especially based on semiconductor Ge and Si.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제18권6호
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• pp.459-463
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• 2017

Hot dip galvanizing in the steel plant is one of the most widely used methods for preventing the corrosion of steel materials including structures, steel sheets, and materials for industrial facilities. While hot dip galvanizing has the advantage of stability and economic feasibility, it has difficulty in repairing equipment and maintaining the facilities due to high-temperature oxidation caused by Zn Fume where molten zinc used in the open spaces. Currently, SM45C (carbon steel plate for mechanical structure, KS standard) is used for the equipment. If a part of the equipment is resistant to high temperature and Zn fume, it is expected to improve equipment life and performance. In this study, the manufactured Ni alloy was tested for its corrosion resistance against Zn fume when it was used in the hot dip galvanizing equipment in the steel plant. Two kinds of materials currently used in the equipment, new Ni alloy and Inconel(typical corrosion-resistant Ni alloy), were selected as the reference groups. Two kinds of molten metal were used to confirm the corrosion of each alloy according to the molten metal. Zn fume was generated by bubbling Ar gas from molten Zn in a furnace($500{\sim}700^{\circ}C$) and the samples were analyzed after 30 days. After 30 days, the specimens were taken out, the oxide layer on the surface was confirmed with an optical microscope and SEM, and the corrosion was confirmed using a potentiodynamic polarization test. Corrosion depends on the type of molten metal.

• Clean Technology
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• 제27권4호
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• pp.315-324
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• 2021

In this study, a vanadium catalyst study was conducted on the various characteristics of the exhaust gas in the Selective-Catalytic-Reduction (SCR) method in which nitrogen oxides emitted from cogeneration using biogas are removed by using ammonia as a reducing agent and a catalyst. V/W/TiO₂, a commercial catalyst, was used as the catalyst in this study, and the effect was confirmed according to the tungsten content under various operating conditions. As a result of the NH₃-SCR experiment, the denitrification performance was confirmed at 380 ~ 450 ℃ more than 95%, and durability to trace amounts of SO₂ was confirmed through the SO₂ durability experiment and TGA analysis. As a result of H₂-TPR analysis, the higher the tungsten content, the better the redox properties. Accordingly, enhanced oxidizing properties were confirmed in the oxidation test for a trace amount of carbon monoxide emitted from the cogeneration. In NH₃-DRIFTs analysis, it was confirmed that the higher the tungsten content, the higher both the Bronsted/Lewis acid sites and the better the thermal durability when tungsten is added to the catalyst. Based on the experiments under various operating conditions, it is considered that a catalyst with a high tungsten content is suitable to be applied to cogeneration using biogas.

• Membrane Journal
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• 제29권2호
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• pp.88-95
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• 2019

Hydrocarbons containing carbon double bonds are generally called olefins and it is extensively used in petro-chemical industry as essential base material. Especially, olefins are essential in polymer synthesis and thus the effective separation and purification of olefins from gas mixture are very important and it gives significant positive effect on the future industrial development. In this study, we fabricated polymeric composite membrane based on poly(1-trimethylsilyl-1-propyne) (PTMSP) for propylene/nitrogen separation and enhancement of its separation performance by grafting amphiphilic copolymer. Furthermore, to accelerate facilitated transport for propylene molecules, Ag salt ($AgBF_4$) and ionic liquid ($EMIM-BF_4$) was incorporated to polymer composite membranes. The neat PTMSP membrane exhibited extremely high gas permeance and low gas selectivity due to its high free volume. To address this issue, PTMSP was grafted with poly(oxyethylene glycol methacrylate) (POEM) and poly(ethylene glycol) behenyl ether methacrylate (PEGBEM). Additionally, the additives such as $AgBF_4$ and $EMIM-BF_4$ further increased the propylene permeance, resulting in increment of propylene/nitrogen selectivity.

• Applied Chemistry for Engineering
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• 제29권6호
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• pp.690-695
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• 2018

Advanced oxidation processes (AOPs) composed of O3 and UV were applied to degrade penicillin (PEN). The degradation efficiency was evaluated in terms of changes in the absorbance (ABS) and total organic carbon (TOC). The combination of $O_3/H_2O_2/UV$ and $O_3/UV$ showed the best performance for the reduction of ABS (100% for 9 min) and TOC (70% for 60 min) values, although the mineralization was uncompleted under the experimental condition in this study. The change in biotoxicy was monitored with Escherichia coli susceptibility and Vibrio fischeri biofluorescence. The E. coli susceptibility was eliminated completely for 9 min by $O_3/UV$, and the toxicity to V. fischeri biofluorescence was 57% reduced by $O_3/H_2O_2/UV$. For the ultimate treatment of PEN, it is suggested that an AOP using $O_3/UV$ is followed by biological treatment, utilizing the enhanced biodegradability by the AOP. During 30 min of $O_3/UV$ treatment, the $BOD_5/COD$ ratio as an indication of biodegradability showed about 4-fold increment, compared to that of using a non-treated sample. TOC removal rate for AOP-pretreated PEN wastewater increased 55% compared to that of using the non-pretreated one through an aerobic biological treatment by Pseudomonas putida for artificial wastewater containing 20 mg/L of PEN. In conclusion, $O_3/UV$ process is recommended as a pretreatment step prior to an aerobic biological process to improve the ultimate degradation of penicillin.