• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.6
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• pp.579-582
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• 2012

Removing residual water in a fuel cell is a critical operational process for managing its performance and controlling its lifetime. Understanding the mechanism of water transport in fuel cells is essential for the design of the water removal process. In this study, an experimental method for measuring the water evaporation rate through a gas diffusion layer, which is a porous medium, under steady-state conditions was developed. Experimental bench tests were conducted to apply the developed method. Then, the effects of various parameters of the drying gas and the gas diffusion layer were experimentally measured. The water evaporation rate increased as the humidity of the drying gas decreased and the flow rate of the drying gas increased. In addition, a thinner gas diffusion layer yielded a higher water evaporation rate.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.353-356
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• 2009

A pivotal mechanical balance of plant for 75kW class molten carbonate fuel cells comprise of a catalytic burner and an ejector which has been designed and tested in KEPRI(Korea Electric Power Research Institute). The catalytic burner, which oxidizes residual fuel in the anode tail gas, was operated at several conditions. Some problems arose due to local overheating or auto-ignition, which could limit the catalyst life. The catalytic burner was designed by considering both gas mixing and gas velocity. Test results showed that the temperature distribution is very uniform. In addition, an ejector is a fluid machinery to be utilized for mixing fluids, maintaining vacuum, and transporting them. The ejector is placed at mixing point between the anode off gas and the cathode off gas or the fresh air Several ejectors were designed and tested to form a suction on the fuel tail gas and balance the differential pressures between anode and cathode over a range of operating conditions. The tests showed that the design of the nozzle and throat played an important role in balancing the anode tail and cathode inlet gas pressures. The 75kW MCFC system built in our ejector and catalytic burner was successfully operated from Novembe, 2008 to April, 2009. It recorded the voltage of 104V at the current of 754A and reached the maximum generating power of 78.5kW DC. The results for both stand-alone and integration into another balance of plant are discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.533-536
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• 2009

The gasification technology is a very flexible and versatile technology to produce a wide variety products such as electricity, steam, hydrogen, Fisher-Tropsch(FT) diesels, Dimethyl Ether(DME), methanol and SNG(Synthetic Natural Gas) with near-zero pollutant emissions. Gasification converts coal and other low-grade feedstocks such as biomass, wastes, residual oil, petroleum coke, etc. to a very clean and usable syngas. Syngas is produced from gasifier including CO, $H_2$, $CO_2$, $N_2$, particulates and smaller quantities of $CH_4$, $NH_3$, $H_2S$, COS and etc. After removing pollutants, syngas can be variously used in energy and environment fields. The pilot-scale coal gasification system has been operated since 1994 at Ajou University in Suwon, Korea. The pilot-scale gasification facility consists of the coal gasifier, the hot gas filtering system, and the acid gas removal (AGR) system. The acid gas such as $H_2S$ and COS is removed in the AGR system before generating electricity by gas engine and producing chemicals like Di-methyl Ether(DME) in the catalytic reactor. The designed operation temperature and pressure of the $H_2S$ removal system are below $50^{\circ}C$ and 8 kg/$cm^2$. The iron chelate solution is used as an absorbent. $H_2S$ is removed below 0.1 ppm in the H2S removal system.

• Journal of the Korean institute of surface engineering
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• v.56 no.1
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• pp.94-103
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• 2023

The effects of carburizing pressure and gas ratio on vacuum carburizing properties (uniformity and surface characteristics) have been studied through the analyses of carbon concentration, hardness, surface color, surface roughness and type of carbon bonding. AISI 4115 steel specimens were carburized with various pressures (1, 5, and 10 Torr) at different locations (P₁, P₂, P₃, P₄, P₅, and P₆) inside a furnace held at 950 ℃. Since the carburizing pressure represents the density of the carburizing gas, it plays an important role in improving the carburizing uniformity according to locations in the furnace. As the carburizing pressure increased, the carburizing uniformity according to the sample location was improved, but the surface of the carburized specimen was discolored due to the residual acetylene gas, which does not contribute to the carburizing reaction. Therefore, the carburizing uniformity and surface discoloration have been improved by injecting acetylene gas (carburizing gas) and nitrogen gas (non-reactive gas) in a specific ratio.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.26-29
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• 2011

Purpose: The general test method of the Korean Pharmacopeia specifies the test method on the clauses of quality control after manufacturing. According to KFDA Guidance for Medicines, standards of residual solvents regulates the maximum permissible dose of acetonitrile as 400 ppm, ethanol as 5,000 ppm, and acetic acid as 5,000 ppm. This study aims at identifying the type of resiual solvents in the final [F-18]FDG vial of an automatic synthesizer and measure its residual quantity. Materials and Methods: The center carried out residual solvents test of [F-18]FDG injection using Agilent Technologies 7890A with a Flame Ionization Detector. The column of Agilent Technologies 7890A used in measuring of residual solvents was CP WAX column ($30m{\times}0.53mm{\times}1.0{\mu}m$) and analysis condition was split mode 1:1 at the initial temperature $70^{\circ}C$ which was increased $20^{\circ}C/minute$ after two minutes and maintained at the final $140^{\circ}C$ for two minutes. The analysis method was as following: Firstly, ethanol-acetonitrile-acetic acid mixture was classified into four types of concentration (250-25-250 ppm, 1,000-100-1,000 ppm, 3,000-300-3,000 ppm, and 6,000-600-6,000 ppm), and $1.0{\mu}L$ of each type of concentration was injected into gas chromatography followed by an analysis of its peak domain. Then, a calibration-curve by the external standard method was drawn based on the analysis result. Results: While ethanol and acetonitrile were detected in TRACERlab MX, FASTlab had additional acetic acid. The residual quantity of the ethanol-acetonitrile-acetic acid mixture evaluated using the calibration-curve was average 72 ppm ethanol, 54 ppm acetonitrile, and 1030 ppm acetic acid for FASTlab, whereas average 439 ppm ethanol and 79 ppm acetonitrile for TRACERlab MX. This indicated that both of them were within the maximum permissible dose. Conclusion: Solvent residues in the [F-18]FDG injection were all within maximum permissible doses and proper to be used to examine a patient. The result indicated that types and quantities of solvent resides of radioactive pharmaceuticals vary depending on the automatic synthesizer.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.6
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• pp.566-569
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• 2007

Purpose: Analysis of volatile organic solvents in 2-deoxy-2-$[^{18}F]$ fluoro-D-glucose ($[^{18}F]$FDG) preparations was performed by gas chromatography (GC), in accordance with USP. Materials and Methods: Analyses were carried out on a Hewlett-Packard 6890 gas chromatography equipped with an FID. Results: We determined the amounts of ethanol and acetonitrile on every batch of our routine $[^{18}F]$FDG preparations, ranging between 5000 ppm and 100 ppm. In our routine preparation of $[^{18}F]$FDG, the amount of acetonitrile and ethanol in the final product were well below the maximum allowable limit described in the USP. Conclusion: Our $[^{18}F]$FDG preparations were in accordance with the suggested USP maximum allowable levels of the quality control analysis of volatile organic compounds.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.240-246
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• 1992

Preparation of soybean oil fatty acid methyl esters (soybean oil FAME) through the transesterification of soybean oil with alkaline catalyst was optimized in terms of contents of residual free fatty acids (FFA) in soybean oil FAME and yield of soybean oil FAME due to the inhibitory effect of FFA on sucrose polyesters synthesis. Soybean oil FAME and residual FFA were analyzed quantitatively by simultaneous gas chromatography on a fused silica capillary column after converting the FFA in soybean oil FAME to tert.-butyldimethylsilyl (TBDMS) derivatives. Transesterification of soybean oil was successfully performed with alkaline catalyst (NaOH, 95%), which resulted in 99.1% yield of soybean oil FAME and less than 0.1% residual FFA contents under the conditions such as $30^{\circ}C$, 20min. and 6:1 molar ratio of anhydrous methanol to soybean oil.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.15 no.2
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• pp.49-54
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• 2009

The effects of filling temperatures of broth and degassing method on the residual oxygen content and gas composition in the pouch and physical strength of packaging material for Samgyetang depending on the contamination of broth on the sealing layer and sterilization process were investigated. The residual oxygen content in the broth and the oxygen proportion in the headspace of package were decreased with the increase of broth temperature at filling into the pouch from 50 to 100. When the products were packaged as air-contained (Air), manually squeezed the upper side of package out to minimize the headspace (Degas) and flushed with nitrogen gas ($N_2$-Flushing) while maintaining the broth temperatures of Samgyetang at 50 or 85. The residual oxygen content and oxygen proportion were increased in the order of $N_2$-Flushing

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.8
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• pp.1168-1174
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• 2017

Objective: The aim of the study was to evaluate the effects of different nitrate levels (150, 300, 450, and 600 ppm $KNO_3$) on the volatile compounds and some other properties of pastırma. Methods: Pastırma samples were produced under the controlled condition and analyses of volatile compounds, and thiobarbituric acid reactive substances (TBARS) as an indicator of lipid oxidation, non-protein nitrogenous matter content as an indicator of proteolysis, color and residual nitrite were carried out on the final product. The profile of volatile compounds of pastırma samples was analyzed by gas chromatography/mass spectrometry using a solid phase microextraction. Results: Nitrate level had a significant effect on pH value (p<0.05) and a very significant effect on TBARS value (p<0.01). No significant differences were determined in terms of $a_w$ value, non-protein nitrogenous substance content, color and residual nitrite between pastırma groups produced by using different nitrate levels. Nitrate level had a significant (p<0.05) or a very significant (p<0.01) effect on some volatile compounds. It was determined that the amounts and counts of volatile compounds were lower in the 450 and especially 600 ppm nitrate levels than 150 and 300 ppm nitrate levels (p<0.05). While the use of 600 ppm nitrate did not cause an increase in residual nitrite levels, the use of 150 ppm nitrate did not negatively affect the color of pastırma. However, the levels of volatile compounds decreased with an increasing level of nitrate. Conclusion: The use of 600 ppm nitrate is not a risk in terms of residual nitrite in pastırma produced under controlled condition, however, this level is not suitable due to decrease in the amount of volatile compounds.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.1
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• pp.59-67
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• 2014

In 1995 Kimchi refrigerator was developed at first, and has used HFC-134a as refrigerant. Kimchi refrigerator has been made 1,044,694 on the basis of 2010, disposed about 160,000 per year. Although mobile air conditioning, commercial refrigerator, general refrigerator is regarded as a major source of HFC-134a, little information is available for its emission characteristics of HFC-134a. This paper addresses the fugitive emission factors of Kimchi refrigerator at use-phase and disposal-phase. The residual quantities of Korean-made fifty three waste Kimchi refrigerators were weighed using a commercial recover of refrigerants to determine the emission factors at the disposal-phase. On the other hand, the emission factors at use-phase were estimated from the residual quantities and operating times. The average residual rate of forty three scarp Kimchi refrigerators is determined to be $74.6{\pm}5.2%$. The emission factor at the use-phase is estimated to be $3.5{\pm}0.8%/yr$ as a result of using average age of 11.7 years and the average residual rate determined here. The emission factor at the disposal-phase is determined to be 31.3% after adopting 58% of the recycling rate of refrigerant reported by Recycling Center. We estimate 3.1 g/yr for the average emission quantity of HFC-134a per operating refrigerator, while 22.5 g for that per waste Kimchi refrigerator. Since the chemical compositions of refrigerant of waste Kimchi refrigerator were the same as those of new refrigerant, it is expected that the HFC-134a recovered from waste Kimchi refrigerator can be reused for refrigerant.