• Journal of the Korean Electrochemical Society
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• v.11 no.1
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• pp.42-46
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• 2008

Even though fuel cell have high efficiency when pure hydrogen from gas tank is used as a fuel source, it is more beneficial to generate hydrogen from city gas (mainly methane) in residential application such as domestic or office environments. Thus hydrogen is generated by reforming process using hydrocarbon. Unfortunately, the reforming process for hydrogen production is accompanied with unavoidable impurities. Impurities such as CO, $CO_2$, $H_2S$, $NH_3$, $CH_4$, and $CH_4$ in hydrogen could cause negative effects on fuel cell performance. Those effects are kinetic losses due to poisoning of the electrode catalysts, ohmic losses due to proton conductivity reduction including membrane and catalyst ionomer layers, and mass transport losses due to degrading catalyst layer structure and hydrophobic property. Hydrogen produced from reformer eventually contains around 73% of $H_2$, 20% or less of $CO_2$, 5.8% of less of $N_2$, or 2% less of $CH_4$, and 10ppm or less of CO. This study is aimed at investigating the effect of carbon dioxide on fuel cell performance. The performance of PEM fuel cell was investigated using current vs. potential experiment, long run(10 hr) test, and electrochemical impedance measurement when the concentrations of carbon dioxide were 10%, 20% and 30%. Also, the concentration of impurity supplied to the fuel cell was verified by gas chromatography(GC).

• Applied Chemistry for Engineering
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• v.18 no.4
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• pp.337-343
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• 2007

The reforming catalyst and the electrodes in fuel cells can be poisoned by the organic sulfur compound which is added as an odorant for checking out the leakage of natural gas, and that makes a big problem of system degradation. In this study, various adsorbents, such as silica, ${\gamma}$-alumina, activated carbon, HZSM-5, Ultra-stable Y zeolite (USY), and beta zeolite (BEA), were utilized to remove tetra-hydrothiophene (THT) and tert-butylmercaptan (TBM), and to confirm the performance in the adsorption of those odorants by using a continuous adsorptive bed. The effects of Si/Al ratio of zeolites, adsorption temperature and the type of balance gas (methane or He) on the adsorption performance in the packed bed have been investigated. In addition, the competitive adsorption between TBM and THT on the adsorbents was also estimated. The result shows that H-type BEA zeolite exhibited the highest adsorption capacity for TBM and THT odorant, and the higher amount of THT was removed adsorptively on the same adsorbent than TBM. The physical and chemical adsorption of those compounds on acid sites of zeolite were confirmed by temperature programmed desorption (TPD) and infrared spectrum (IR) analyses.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.301-305
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• 2007

The performance of polymer electrolyte membrane fuel cell could be decreased due to coolant leaked from connection part. Micro pump was used to put small amount of coolant and investigate the effect on fuel cell. The stoichiometric ratio of hydrogen/air was 1.5/2.0, both side of gas was fully humidified, and current density of $400mA/cm^2$ was used as standard condition in this experiment. Constant current method was used to check performance recovery from coolant effect in 3 cell stack. The performance was recovered when coolant was injected in cathode side. On the other hand, the performance was not recovered when coolant was injected in anode side. Ethylene glycol could be converted to CO in oxidation process and cause poisoning effect on platinum catalyst or be adhered on GDL and cause gas diffusion block effect resulting performance decrease. Water with nitrogen gas was supplied in anode side to check performance recovery. Polarization curve, cyclic voltammetry, electrochemical impedance spectroscopy was used to check performance, and gas chromatography was used to check coolant concentration. Constant current method was not enough in full recovery of performance. However, water injection method was proved good method in full recovery of performance.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.101-101
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• 2017

Beta-glucan is a polymerized polysaccharide on beta-1,3 chemical bonds. It has the main pharmacological action of various anticancer mushrooms and is colorless and odorless. In addition, it enhances phagocytosis of macrophages against mycobacterium tuberculosism and increases resistance of host against food poisoning bacteria. Owing to these advantages, beta-glucan was used in various health supplement foods such as immune boosters, hypotensive agent and hypoglycemic agent. Our study was aimed to investigate the effective components of beta-glucan, which was optimized via the contents of Sarcodon aspratus and rice bran. First, the mixture ratio condition of Sarcodon aspratus and rice bran were respectively 10:0, 7:3, 5:5, 3:7, and 0:10. The raw materials were fabricated using hot water extraction method. Distilled water of 100 mL was added to the raw material and extracted. After the extraction processed, the content of effective components was analyzed. The absorbance of beta-glucan was measured using a beta-glucan kit (Megazyme, (1-3) (1-4) BETA-D-GLUCAN ASSAY KIT). The absorbance analysis was repeated three times for accurate analysis. After the extracts were lyophilized, the yields of extracted raw materials according to the mixture ratio conditions of Sarcodon aspratus and rice bran (10:0, 7:3, 5:5, 3:7, and 0:10) were respectively 33.1%, 34.5%, 35.3%, 30.7%, and 24.3%. The absorbance was 1.52, 1.47, 1.50, 1.79, and 1.56, respectively. As a result, the optimum ratio of beta-glucan is 3:7 at Sarcodon aspratus and rice bran. This study suggested that the optimal amount of beta-glucan could be used as a health supplement foods and food additive such as immune boosters, hypotensive agent and hypoglycemic agent. However, the new condition (temperature, time) of hot water extraction to maximize the content of beta-glucan could be considered, could be necessary to compare with the existing extracts.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.141-145
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• 2007

Due to their excellent catalytic activity with respect to methanol oxidation on platinum at low temperature, platinum nanosized catalysts have been a topic of great interest for use in direct methanol fuel cells (DMFCs). Since pure platinum is readily poisoned by CO, a by-product of methanol electrooxidation, and is extremely expensive, a number of efforts to design and characterize Pt-based alloy nanosized catalysts or Pt nanophase-support composites have been attempted in order to reduce or relieve the CO poisoning effect. In this review paper, we summarize these efforts based upon our recent research results. The Pt-based nanocatalysts were designed by chemical synthesis and thin-film technology, and were characterized by a variety of analyses. According to bifunctional mechanism, it was concluded that good alloy formation with $2^{nd}$ metal (e.g., Ru) as well as the metallic state and optimum portion of Ru element in the anode catalyst contribute to an enhanced catalytic activity for methanol electrooxidation. In addition, we found that the modified electronic properties of platinum in Pt alloy electrodes as well as the surface and bulk structure of Pt alloys with a proper composition could be attributed to a higher catalytic activity for methanol electooxdation. Proton conducting contribution of nanosized electrocatalysts should also be considered to be excellent in methanol electrooxidation (Spillover effect). Finally, we confirmed the ensemble effect, which combined all above effects, in Pt-based nanocatalsyts especially, such as PtRuRhNi and $PtRuWO_{3}$, contribute to an enhanced catalytic activity.

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.139-143
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• 2005

We evaluated grapefruit seed extract for antibacterial activity at varying time intervals and concentration levels against heat tolerant and spore-forming Bacillus stearothermophilus, mesophilic Bacillus subtilis, and food poisoning Staphylococcus aureus. Grapefruit seed extract showed growth inhibitory activity against B. stearothemophilus and B. subtilis, and S. aureus at the level of 0.01 tp 0.03% in nutrient broth. However, when applied to soymilk in a market, grapefruit seed extract at the level above 0.2% effectively inhibited the growth of B. stearothermophilus, However, it failed to completely sterilize the test organisms. On the other hand, B. subtilis and S. aureus were completely sterilized at the level of 0.2% within 48 hrs and 72 h, respectively. The higher concentration of grapefruit seed extracts showed more effective antibacterial activities against the test organisms, but caused deteriorated organoleptic quality and emulsion stability. We could conclude, by applying grapefruit seed extract (0.015%) with thermal treatment (10 min at $121^{\circ}C$) that the microbial stability of commercial soymilk was enhanced greatly.

• Biomedical Science Letters
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• v.13 no.1
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• pp.47-53
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• 2007

Due to wide abuse of antibiotics both in human and livestock use, the advent and spread of multidrug resistant (MDR) pathogens becomes a serious health problem all over the world. Since the development of new antibiotics is at a standstill in pharmaceutical industry, the choice of therapeutic antibiotics is getting narrower. In this study, in an effort to search new antibiotics, the antimicrobial activity of Paenibacillus DY1 isolated from Korean soil was characterized on its growth inhibition spectrum against various health threatening MDR strains, with its stability and chemical structure. Extracellular culture filtrate of Paenibacillus DY1 effectively inhibits the growth of all the tested MDR enteropathogenic Eshcherichia coli, enterohemolytic E. coli, and enterotoxigenic E. coli strains, at a similar level to that on the nonresistant control E. coli strains. It showed significant growth inhibition effect against the causative agents of class one legal communicable disease, MDR Salmonella typhi, MDR Salmonella paratyphi A, food poisoning bacteria, MDR Salmonella typhimurium, and other MDR Salmonella spp. The growth of all of 10 different MDR Shigella spp. strains and 6 different Vibrio spp. strains tested was also inhibited. The antimicrobial activity of Paenibacillus DY1 was well preserved after heat treatment, and was also stable in both alkaline and acidic environment. The antimicrobial activity was partially purified with Diaion HP20 column and TLC. By NMR study, the putative structure of the activity was postulated as an alkane having hydroxyl groups.

• Journal of The Korean Society of Clinical Toxicology
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• v.4 no.1
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• pp.25-31
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• 2006

Purpose: In the year of 2005, it enforced the basic study for establishing program of Poison Control Center by National Institute of Toxicologic Research. The object of our survey is to analyze the characteristics of intoxication from the City of Goyang by same protocol. Methods: We retrospectively reviewed the data of medical records of the intoxication patient in the two hospitals of the Goyang from 2004 June 1st to 2005 May 31th. The investigation protocol applied the TESS report form which was used from the Basic study for establishing program of Poison Control Center. Results: The intoxication patients were total 269 persons, the patients of A hospital were 184 persons, B hospital were 185 persons. The most common intoxication materials were medicines, in afterwords it was an agricultural chemical. The most common place of intoxication was the home. The intentional suicidal attempts in the reason of intoxication were 51.2%. The rate of the patients who discharges from the emergency department was 50.4% and death rate was 4.3%. Conclusion: We concluded that the continuous and systemic report and analysis should be accomplished from the Goyang area.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.1
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• pp.32-40
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• 2008

Methyl bromide has been used as a representative fumigant for quarantine, and several poisoning cases have occurred recently by this chemical in Korea. The purpose of this study is to evaluate workers' exposures to airborne methyl bromide in the importing and exporting plant products quarantine companies. Air samples were collected 400/200 mg Anasorb 747TM and were analyzed by gas chromatograph /flame ionization detector according to the Occupational Safety and Health Agency (OSHA) Method PV2040. Geometric mean (GM) and arithmetic mean (AM) of total 27 workers' exposure concentrations to airborne methyl bromide were 1.12 ppm and 0.24 ppm, respectively. Two exposures(12.1 ppm and 12 ppm as 8hr-TWA) of total 27 workers' exposures exceeded the Korean standard (5 ppm) of Ministry Labor, while 4 exposures (15%) exceeded the Threshold Limit Value (TLV) (1 ppm) of American Conference of Governmental Industrial Hygienists (ACGIH). Seven samples (11%) of total 63 short-term air samples exceeded the OSHA Permissible Exposure Limit (PEL) 20 ppm (Ceiling). The opening (management) task in wood fumigation by tent showed the highest short-term exposure concentrations (AM: 18.6 ppm, GM: 0.58 ppm, maximum: 340.7 ppm). The maximum level in treatment task of the same process was 2.01 ppm. Methyl bromide concentrations in opening operation was significantly higher than that in treatment operation (p<0.05). In conclusion, the GM of workers' 8hr-TWA exposures to airborne methyl chloride in the importing/exporting plant quarantine industry was estimated below the ACGIH TLV (1 ppm). However, opening task in the fumigation of wood being covered with tent or fumigation of pant products in container showed the levels exceeding ACGIH TLV (1 ppm), and opening task in the fumigation of wood being covered with tent showed the level exceeding the Korean standard of Ministry of Labor (5 ppm).

• Korean Journal of Veterinary Research
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• v.60 no.3
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• pp.105-108
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• 2020

These days abattoirs' hygiene of Korea is regulated by Hazzard Analysis Critical Control Point (HACCP). Although 20 years have been left since first HACCP was adjusted in Korea, 12% of abattoirs got inconsistence on evaluations. Food poisoning caused by bacteria feces like pathogenic Escherichia coli and Salmonella has not decreased. These bacteria on meat cross-contaminate at the abattoir. Therefore, field verification of abattoir's critical control point (CCP) and experiments to find alternative ways of the CCP were conducted. The aerobic bacteria were measured before and after high-pressure water based washing process set as CCP in most abattoirs. Four parts of cattle carcasses were selected to apply sponge-swab method. The effects were < 1 log reduction which is not significant. Lactic acid (LC), chlorine dioxide (ClO₂) and slightly acidic electrolyzed water (SAEW) were used to measure the effect of reducing bacteria on beef by the different time. LC has 1.24-2.02 log reduction for aerobic bacteria. ClO₂ has 1.44-1.96 log reduction for aerobic bacteria. SAEW has 1.1-1.91 log reduction for aerobic bacteria. There was significant difference according to concentrations (p < 0.05). This study presents legitimacy for hygiene improvement of CCP by field verification. In addition, chemical disinfectants that can be mechanically applied have better reduction effects of high-pressure washing.