• Membrane Journal
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• v.33 no.4
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• pp.222-232
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• 2023

In this study, a hollow fiber support membrane was prepared by a non-solvent induced phase separation (NIPS) method using a polysulfone (PSf). The prepared hollow fiber support membrane was coated with PDMS and Pebax to prepare a hollow fiber composite membrane. The prepared composite membrane was measured for permeance and selectivity for pure CO₂, H₂, O₂ and N₂. Gas separation performance of the module having the highest selectivity (CO₂/H₂) among the prepared composite membrane modules was measured according to the change in stage cut using simulated gas. The composition of the simulated gas used at this time was 70% CO₂ and 30% H₂. In the 1 stage experiment, it was possible to obtain values of about 60% of H₂ concentration and 12% of H₂ recovery. In order to overcome the low H₂ concentration and recovery, 2 stage serial test was performed, and through this, it was possible to achieve 70% H₂ concentration and 70% recovery. Through this, it was possible to derive a separation process configuration for CO₂/H₂ separation.

• Journal of Pharmacopuncture
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• v.11 no.1
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• pp.177-187
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• 2008

Objectives : This study was performed to analyze the effective components of essential oil obtained from Yongdamsagantang, which has been efficacious against leukorrhea in gynecologic diseases. Methods : I obtained the essential oils of Yongdamsagan-tang by hydrodistillation extraction method and supercritical fluid extraction(SFE) method, and then I analyzed those by GC/MS(Gas Chromatography/Mass Spectrum). Results : 1. The optimum SFE(Supercritical Fluid Extraction) condition was obtained in the following experiment conditions: pressure 200atm, temperature $45^{\circ}C$, duration of extraction 25minutes. 2. With GC(Gas Chromatography) and GC/MS(Gas Chromato- graphy/Mass Spectrum) analysis, I identified 37 compounds in the Yongdamsagan-tang's essential oil obtained through the SFE method. The main compounds were as follows : 3-Methyl-but-2-enoic acid,2,2-dimethyl-8-oxo-3,4-dihydro-2H,8H -pyrano[3,2-g]chromen-3-yl ester(49.81%), (Z)-6-Pentadecen-1 -ol(3.19%), (-)-Spathulenol(2.40%). 3. I identified 4 compounds in the Yongdamsagan-tang's essential oil obtained through the hydrodistillation method. The main compounds were as follows : 3-Methyl-but-2-enoic acid, 2,2-dimethyl-8-oxo-3,4-dihydro-2H,8H-pyrano [3,2-g]chromen-3-yl ester(2.61%). 4. 3-Methy I-but-2-enoic acid, 2,2-dimethyl-8-oxo-3,4-dihydro-2H,8H-pyrano[3,2-g] chromen-3-yl ester, all were identified in both the SFE method and the hydrodistillation method, but the others were not identified in common. 5. I also conducted an additional test in order to examine the essential oil's antimicrobial action against bacteria. Both MIC(Minimum Inhibitory Concentrations) and MBC(Minimum Bactericidal Concentrations) were $0.125mg/m{\ell}$ against N. meningitidis, however MIC and MBC were $1.0mg/m{\ell}$ in antimicrobial action against 12 different genera of bacteria.

• Journal of the Korean Applied Science and Technology
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• v.31 no.2
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• pp.285-295
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• 2014

Citrus essential oil were extracted from citron peel of cultivated in Gohong (CCP) using environmentally friendly supercritical carbon dioxide method. Antioxidant activity and aroma composition of the essential oils extracted by the SC-$CO_2$ method were evaluated by comparing with those extracted by organic solvent method. Fatty acid composition, DPPH scavenging, and antioxidant activity of the oils obtained by different extraction condition of SC-$CO_2$ method were investigated and their antioxidant activities were compared with commercially available lavender, eucalyptus and tea tree oils. As the results, linoleic acid was most abundantly found from CCP oil extracted by the SC-$CO_2$ method and cis-11,144-eicosadienoic acids was second abundantly found. Radical scavenging ability of DPPH was 98% when the concentration of CCP oil was 50 mg/mL. This scavenging ability increased with the increase of oil concentration. On the other hand, flavonoids content (84 mg/100g) of the CCP oil extracted by the SC-$CO_2$ method was slightly higher than that (75 mg/100g) by hexane extraction. The results, obtained from CCP oil by GC-MS, indicated that, among 66 components, the content of terpenes was 55.8% and limonene was 27.3%.

• The Journal of Sustainable Design and Educational Environment Research
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• v.9 no.1
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• pp.1-10
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• 2010

It is indispensable for child care centers to investigate and manage indoor air quality (IAQ) because they perform education and day care for children who usually have weak immunity. Nevertheless, there is insufficient research being done, given its importance. This study aims to investigate indoor pollutants' concentration and to seek the causes in order to improve the air quality conditions. Also it aims to secure data which can be used for further researches. Measurements were performed for air temperature, relative humidity, carbon dioxide, carbon monoxide, fine particle mass, formaldehyde and volatile organic compounds. Temperature, humidity, CO and CO2 were measured 30times(1min/time) and PM10 was measured 10times (3min/time). Formaldehyde and volatile organic compounds were measured and analyzed based on The Indoor Air Quality Official Test Method. The results show that the temperatures were within the comfort zone in over half of the centers. CO2 was found to be the main pollutants as its concentration exceeded the IAQ standard. The concentrations of TVOC and PM10 exceeded the standard, by 32% and 24% respectively, whereas those of HCHO and CO were under the standard. HCHO and CO concentrations were under the guideline. 24% of child care centers for education were found to exceed the standard in 2 or more of the pollutants. 82% of were found to exceed the standard by 1 or more. Therefor it is requested for IAQ to manage and improve in child care center for education.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.4
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• pp.13-20
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• 2013

Due to the global warming, international agreements have been propelled by industrialized countries. These days, there are various studies and projects to reduce the carbon emission quantity in South Korea, because South Korea is a strong candidate for a newly industrialized nation by Kyoto Protocol. Therefore, this study arranges plans to create various thematic map by producing database that can manage various datum based on grid spatial objects to manage quantity of forest biomass and carbon dioxide. Moreover, this study designs a system to create forest biomass by using the best method of calculation with LiDAR data and KOMPSAT-2 satellite images. In addition, this study designs a biomass monitoring system for public institutions to register biomass, suggesting actual plans to extract, manage, and utilized forest biomass.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.9
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• pp.1561-1565
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• 2007

According to thermal degradation on power transformers, it is known that electrical, mechanical and chemical characteristics for power transformer's oil-paper are changed. In the chemical property, especially, when the kraft paper is aged, the cellulose polymer chains break down into shorter lengths. It causes decrease in both tensile strength and degree of polymerization of paper insulation. Also the paper breakdown is accompanied by an increase in the content of various furanic compounds within the dielectric liquid. It is known that furanic components in transformer oil come only from the decomposition of insulating paper rather than from the oil itself. Therefore the analysis of furanic degradation products provides a complementary technique to dissolved gas analysis for monitoring transformers when we evaluate the aging of insulating paper by the total concentration of carbon monoxide and carbon dioxide dissolved in oil only. Recently, the analysis of furanic compounds by high performance liquid chromatography(HPLC) using IEC 61198 method for estimating degradation of paper insulation in power transformers has been used more conveniently for assessment of oil-paper. It is know that the main products which is produced by aging are 2-furfuryl alcohol, 2-furaldehyde(furfural), 2-furoic acid, 2-acetylfuran, 5-methyl-2-furaldehyde, and 5-hydroxymethyl-2-furaldehyde. For investigating the accelerated aging process of oil-paper samples we manufactured accelerating aging equipment and we estimated variation of insulations at $140^{\circ}C$ temp. during 500 hours. Typical transformer proportions of copper, silicon steel and iron have been added to oil-paper insulation during the aging process. The oil-paper insulation samples have been measured at intervals of 100 hours. Finally we have analyzed that 2-furoic acid and 2-acetylfuran products of furanic compounds were detected by HPLC, and their concentrations were increased with accelerated aging time.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.77-82
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• 2004

Quantifying rates of microbial processes under subsurface conditions is difficult, and is most commonly approximated by laboratory studies using aquifer materials. In this study a single-well, 'push-pull' test method is adapted for the in situ determination of denitrification rates in groundwater aquifers. The rates of stepwise reduction of nitrate to nitrite, nitrous oxide, and molecular nitrogen were determined by performing a series of push-pull tests at an experimental well field of Korea University. A single Transport Test, one Biostimulation Test, and four Activity Tests were conducted for this study. Transport tests are conducted to evaluate the mobility of solutes used in subsequent tests. These included bromide (a conservative tracer), fumarate (a carbon and/or source), and nitrate (an electron acceptor). At this site, extraction phase breakthrough curves for all solutes were similar, indicating apparent conservative transport of the solutes prior to biostimulation. Biostimulation tests were conducted to stimulate the activity of indigenous heterotrophic denitrifyinc microorganisms. Biostimulation was detected by the simultaneous production of carbon dioxide and nitrite after each injection. Activity tests were conducted to quantify rates of nitrate, nitrite, and nitrous oxide reduction. Estimated zero-order degradation rates decreased in the order nitrate '||'&'||'gt; nitrite '||'&'||'gt; nitrous oxide. The series of push-pull tests developed and field tested in this study should prove useful for conducting rapid, low-cost feasibi1ity assessments for in situ denitrification in nitrate-contaminated aquifers.

• Korean Chemical Engineering Research
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• v.43 no.4
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• pp.467-473
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• 2005

Liquid phase nitrous oxide ($N_2O$) contains air, carbon monoxide, water, carbon dioxide and NOx as main impurities. It is known to be very dangerous to obtain a very pure $N_2O$ product by using solidification at low temperature. In this study a new method to obtain a high purity of $N_2O$ product based on a continuous distillation process was introduced. For the modeling of the continuous distillation process to obtain a product having a purity over 99.999％ of $N_2O$ stream, Intalox wire gauze packing- No. SCH-80S gauze packing column was used. Peng-Robinson equation of state was used for the modeling of the continuous distillation process and refrigeration system. Computational results performed in this work showed a good agreement with Aspen Plus simulation results.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.335-342
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• 2018

Various technologies to cope with the energy and environmental issues related to the chemical and electric power industry are in development and demonstration stage. Especially, the absorption process of carbon dioxide ($CO_2$) using amine solution is a key technology of the $CO_2$ capture and storage (CCS). In this study, we identify the major risk factors and suggest strategies for safety improvement by analyzing and assessing commercial the amine-based $CO_2$ separation process. HAZOP method was used to assess the risk for the process. We provide facilities and operational strategies to mitigate or eliminate major risk factors by assessing the relative ranks of identified risk factors using a risk matrix.

• KIEAE Journal
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• v.16 no.3
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• pp.71-76
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• 2016

Purpose: This study aimed at improving the indoor environment of the office building by measuring the indoor environment and conducting a survey. Method: The measurement was conducted from January 13 to March 16 in 2012, targeting 44 sites in same office building located in Seoul, South Korea. The lists of measurement such as dry-blub temperature, relative humidity, formaldehyde (HCHO), asbestos, carbon monoxide (CO), carbon dioxide (CO2), volatile organic compounds (VOCs) and particle pollution (PM10) were measured. In addition, illuminance which belongs to light environment and noise in sound[acoustical] environment were measured respectively. Result: The buildings showed overall pleasant conditions. In terms of the thermal, air, sound, and visual environment, each measurements were satisfied with the requirements in standard, within pleasant ranges, except several sites. However, the survey results were revealed that the office workers were mostly dissatisfied with their indoor environment. Given that the measured values were mostly within standards, the results of survey might have resulted from a compensation mentality biased toward the subjects in psychological terms.