• KSBB Journal
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• v.15 no.4
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• pp.408-410
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• 2000

The supercritical fluid extraction(SFE) technique was applied for the isolation and purification of nonpolar physiologically acitve mateials from Agaricus blazei fruiting bodies. the qualitative analysis of extract was accomplished by gas chromatography-mass spectrometer(GC-MS) and extract was determined as linoleic acid(cis-9 cis-12-octadecadienoic acid) In order to obtain the optimum operating conditions of supercritical fluid extraction process the various temperatures and pressures were applied for process operation. From the comparison of exraction efficiencies $50^{\circ}C and 200 kg_f/cm^2$ were determined as optimum conditions.

• Journal of the Korean Chemical Society
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• v.66 no.4
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• pp.269-277
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• 2022

In recent years, carbon-based catalysts have become a research hotspot in environmental governance applications. Carbon-based catalysts have large surface areas, porous structures, multi-surface functional groups and excellent electron transfer capabilities, and can synergistically exhibit adsorption and catalytic performance. This article reviews the research progress of carbon-based catalysts in environmental governance, mainly including its application in wastewater treatment, exhaust gas purification and soil remediation. In view of the current difficulties in the research of carbon-based catalysts, the development prospects are proposed. We hope that this review will provide convenience for new entrants and researchers intending to employ carbon-based catalysts for the remediation of contaminated environment.

• Clean Technology
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• v.9 no.1
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• pp.29-35
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• 2003

The methods for improving epichlorohydrin process was investigated by carrying out experiments on hypochlorination reaction, from which dichlorohydrin is produced by reacting with allyl chloride and chlorine. As the recycle water from PVC plant was used instead of industrial water for reaction, the effect of recycle water on the reaction yield was studied. It was shown from this experiment that the recycle water rarely affected on the ratio between products. TCPA, which was almost of byproducts, could be removed before purification process using "extractant A". This could prevent additional side reaction by TCPA and reduced energy to separate it in purification part. The change of product yield was observed as the chlorine gas addition decreases which reacted with allyl chloride. It seems that the yield of major products didn't change almost, but the byproducts showed rather reduced trend with decreasing chlorine gas.

• Clean Technology
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• v.20 no.4
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• pp.406-414
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• 2014

Biogas is a gaseous mixture produced from microbial digestion of organic materials in the absence of oxygen. Raw biogas, depending upon organic materials, digestion time and process conditions, contains about 45-75% methane, 30-50% carbon dioxide, 0.3% of hydrogen sulfide gas and fraction of water vapor. To achieve the standard composition of the biogas the treatment techniques like absorption or membrane separation was performed for the resourcing of biogas. In this paper the experimental results of the methane purification in simulated biogas mixture consisted of methane, carbon dioxide and hydrogen sulfide were presented. The composite membrane is manufactured within polysulfone in order to increase the separation performances for the gaseous mixtures of $CO_2$ and $CH_4$ which are main components of the biogas. The effects of feed pressures and mixed gas on the separation of $CO_2-CH_4$ by membrane are investigated. Chelate chemical was utilized to treat the purification of methane from the $H_2S$ concentration of 0.3%.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.51.3-51.3
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• 2010

Due to the recent public awareness of global warming and sustainable economic growth, there has been a growing interest in alternative clean energy sources. Hydrogen is considered as a clean fuel for the next generation. One of the technical challenges related to the use of hydrogen is safe monitoring of the hydrogen leak during separation, purification and transportation. For detecting various gases, chemiresistor-type gas sensors have been widely studied and used due to their well-established detection scheme and low cost. However, it is known that many of them have the limited sensitivity and slow response time, when used at low temperature conditions. In our work, a sensor based on Schottky barriers at the electrode/sensing material interface showed promising results that can be utilized for developing fast and highly sensitive gas sensors. Our hydrogen sensor was designed and fabricated based on indium oxide (In2O3)-doped tin oxide (SnO2) semiconductor nanoparticles with platinum (Pt) nanoclusters in combination with interdigitated electrodes. The sensor showed the sensitivity as high as $10^7%$ (Rair/Rgas) and the detection limit as low as 30 ppm. The sensor characteristics could be obtained via optimized materials synthesis route and sensor electrode design. Not only the contribution of electrical resistance from the film itself but also the interfacial effect was identified as an important factor that contribute significantly to the overall sensor characteristics. This promises the applicability of the developed sensor for monitoring hydrogen leak at room temperature.

• Resources Recycling
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• v.6 no.4
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• pp.3-10
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• 1997

Electric are furnace dust (EAF dust) generated in steel production based on scrap melting is contained Zn and Fe about 25 and 30 percent by weight, respectively. From a metallurgical point of view, the dust could be regarded as a raw material for Zn and Fe source. To recover the Zn in the metal from EAF dust, many system are proposed such as Arc Plasma Furmace and Pb splasher method. In this study, to recover high purity Zn from Pb splasing alloy, Zn distillation is carried out at the temperature of 1123, 1173, 1223, 1273 K, the gas flow rate of 2.5, 5.0, 8.0 Ni/min and the distilling time of 10, 30, 60, 90 minutes. The main results obtained from this study are as follows:(1) The amount of evaporated Zn and its evaporating rate increased with increasing temperature, but purity of Zn decreased with increasing temperature. Optimum temperature range was found out to be between 1173∼1223K. (2) The amount of evaporated Zn and evaporation rate increased with increasing gas flow rate at a given temperature and distillation time. Gas flow rate has more influence over the amount of evaporated Zn and evaporation rate with increasing temperature.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.61-66
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• 2009

An analytical method based on solid-phase extraction and gas chromatography / mass spectrometry has been developed for measurement of acaricides (amitraz, bromopropylate, coumaphos, cymiazole, and tetradifon) in honey sample. In the stability test of acaricides in honey, amitraz underwent a rapid degradation into 2,4-dimethylaniline (DMA), 2,4-dimethylphenylformamide (DMPF), and N-(2,4-dimethylphenyl)-N'-methylformamidine (DMPMF), whileas other acaricides were found to be stable even for over three months. Extraction of five acaricides from 5g of honey sample was carried out by liquid-liquid extraction using 20mL of ethylacetate. For purification, Florisil-SPE cartridge with elution of 5mL of n-hexane/ acetone (55:45, v/v) was found to remove interferences effectively. Quantification was performed using gas chromatography / mass spectrometry in the selected ion monitoring mode. Spiking experiments were carried out to determine the recovery, precision, and limits of detection (LODs) of the method. The overall recovery values from honey spiked at 0.02 and 0.20 ${\mu}g/g$ levels, respectively, were found to be greater than 75% for all acaricides. The method detection limits for acaricides were ranged from 0.1 to 3 ppb. The developed method in this study was applied for the monitoring of acaricides in honey products collected from urban markets in Korea.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.213-213
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• 2000

Direct laser vaporization of transition-metal(Co, Ni)/graphite composite pellet produced single wall carbon naotubes(SWNT) in the condensing vapor in a heated flow cylinder-type tube furnace, Transition metal/graphite composite pellet target was made by mixing graphite, Co, and Ni in 98:1:1 atomic weight ratios, pressing the mixed powder, and curing it. The target was placed in a tube furnace maintained at 1200$^{\circ}C$ and Ar inert collision gas continuously flowed into the tube. The 2nd harmonic, 532nm wavelength light from Nd-YAG laser was used to vaporize the tube. The carbon nanotubes produced by the laser vaporization were accumulated on quartz tube wall. The raw carbon nanotube materials were purified with surfactants(Triton X-100) in a ultrasonicator. These carbon nanotubes were analyzed using SEM, XRD, and Raman spectroscopic method. The carbon nanotube growth on the Ni-patterned Si substrate was investigated by the CVD process. Transition-metal, Ni and CH4 gas were used as a catalyst and a reactant gas, respectively. The structure and the phonon frequencies of the carbon nanotubes formed on the patterned Si substrate were measured by SEM and Raman spectrometer.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.7
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• pp.64-70
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• 2022

The aim of this study is to improve the purification efficiency of odor gas by increasing the contact area between an odor gas and adsorbent. To analyze the flow in the adsorption tower, the flow characteristics in the hollow activated carbon-adsorption tower are identified by applying the loss model, which is a porous flow analysis model. The flow characteristics are investigated for pressure loss, velocity distribution, turbulent kinetic energy, and residence time distribution. The results show that the hollow adsorption tower performs better than the solid adsorption tower in terms of pressure loss and performance. The inner diameter of the hollow region inside the adsorption tower is 0.64 m (Di/Do = 0.37). Furthermore, the adsorbent performance is unaffected even when adsorbent stages are installed to replace the adsorbent.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.6
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• pp.594-600
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• 2023

In this study, a process model and optimization design direction for a hydrogen production plant through ammonia decomposition are presented. If the reactor decomposition rate is designed to approach 100%, the amount of catalyst increases and the devices that make up the entire system also have a large design capacity. However, if the characteristics of the hydrogen regeneration process are reflected in the design of the reactor, it becomes possible to satisfy the total flow rate of fuel gas with the discharged tail gas flow rate. Analyzing the plant process simulation results, it was confirmed that when an appropriate decomposition rate is maintained in the reactor, the phenomenon of excess or shortage of fuel gas disappears. In addition, it became possible to reduce the amount of catalyst required and design the optimized capacity of the relevant processes.