• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2442-2444
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• 2007

CO adsorbates on the surface of Pt supported on carbon catalysts (Pt/C) were investigated by CO stripping voltammetry. Three types of CO adsorbed samples were prepared: by methanol dehydrogenation only (COm), by CO gas bubbling only (COg), and by methanol dehydrogenation followed by CO gas bubbling (COm+g). Our coverage data show that CO gas can be adsorbed on Pt/C catalyst already saturated with CO adsorbates by methanol dehydrogenation. The COm+g sample showed the properties of both COm as well as COg samples in terms of the potential although the CO adsorbed by dehydrogenation was completely exchanged with CO in the electrolyte solution. Therefore, the oxidation pathways of CO on Pt/C were observed to depend on the initial adsorption conditions of CO more strongly than on the CO coverage. Our results imply that an initial CO poisoning condition in fuel cell operation is an important factor to determine the difficulty in removing the adsorbed CO and confirm that the properties of the adsorbed CO do not change even with chemical replacement with CO in different conditions. In addition, our results indicate a low CO surface mobility on the Pt in an electrolyte solution.

• Journal of Power Electronics
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• v.11 no.1
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• pp.82-89
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• 2011

Differences in the frequency characteristic applied to a ripple current may shorten fuel cell life span and worsen the fuel efficiency. Therefore, this paper presents an experimental analysis of the ripple current applied variable frequency characteristic in a polymer electrolyte membrane fuel cell (PEMFC). This paper provides the first attempt to examine the impact of ripple current through immediate measurements on a single cell test. After cycling for hours at three frequencies, each polarization and impedance curve is obtained and compared with those of a fuel cell. Through experimental results, it can be absolutely concluded that low frequency ripple current leads to long-term degradation of a fuel cell. Three different PEMFC failures such as membrane dehydration, flooding and carbon monoxide (CO) poisoning that lead to an increase in the impedance magnitude at low frequencies are simply introduced.

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1559-1563
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• 2004

The topoisomerase II poisoning effect of certain protoberberine alkaloids is associated with anti-cancer activity. Structure-activity relationships of protoberberine analogues substituted on the ring protons reveal that substitution at the C19 position is an important determinant of biological activity. In this study, the effects of substituent modification at the C19 position on the interaction of protoberberines with DNA are determined using UV and NMR spectroscopy. The line broadening effect on aliphatic resonances, chemical shift changes of the imino protons of HP14 upon berberine and berberrubine binding to HP14, and the rate of the exchange process between protoberberine analogs bound indicate that berberrubine binds HP14 more specifically than berberine. In addition, the free HP14 is altered by the substituent at the 19-position. UV spectra of berberrubine have shown a hypochromic effect together with a slight red shift, which are usually regarded as characteristics of DNA intercalation. These results are consistent with our previous report that the berberrubine is partially intercalated with HP14 with molar ratio 1 : 1, whereas a non-specific interaction is predominant between the berberine and HP14.

• Journal of Electrochemical Science and Technology
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• v.4 no.1
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• pp.41-45
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• 2013

Platinum is a well known element which shows a significant electrocatalytic activity in many important applications. In glucose sensor, because of the poisoning effect of reaction intermediates and the low surface area, the electrocatalytic activity towards the glucose oxidation is low which cause the low sensitivity. So, we fabricate a nanoporous PtZn alloy electrode by deposition-dissolution method. It provides a high active surface and a large enzyme encapsulating space per unit area when it used for an enzymatic glucose sensor. Glucose oxidase was immobilized on the electrode surface by capping with PEDOT composite and PPDA. The composite and PPDA also can exclude the interference ion such as ascorbic acid and uric acid to improve the selectivity. The surface area was determined by cyclic voltametry method and the surface structure and the element were analyzed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscopy (EDX), respectively. The sensitivity is $13.5{\mu}A/mM\;cm^2$. It is a remarkable value with such simply prepared senor has high selectivity.

• Journal of Sensor Science and Technology
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• v.28 no.3
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• pp.139-145
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• 2019

Precautionary detection of chemical warfare agents (CWAs) has been an important global issue mainly owing to their toxicity. To achieve proper detection, many studies have been conducted to develop sensitive gas sensors for CWAs. In particular, metal-oxide semi-conductors (MOS) have been investigated as promising sensing materials owing to their abundance in nature and excellent sensitivity. In this review, we mainly focus on various MOS-based gas sensors that have been fabricated for the detection of two specific CWA simulants, 2-chloroethyl ethyl sulfide (2-CEES) and dimethyl methyl phosphonate (DMMP), which are simulants of sulfur mustard and sarin, respectively. In the case of 2-CEES, we mainly discuss $CdSnO_3-$ and ZnO-based sensors and their reaction mechanisms. In addition, a method to improve the selectivity of ZnO-based sensors is mentioned. Various sensors and their sensing mechanisms have been introduced for the detection of DMMP. As the reaction with DMMP may directly affect the sensing properties of MOS, this paper includes previous studies on its poisoning effect. Finally, promising sensing materials for both gases are proposed.

• Journal of the FoodService Safety
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• v.4 no.1
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• pp.1-6
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• 2023

This study was conducted to evaluate the chemical hazards of 74 kinds of commercial anchovy fish sauce in Korea by measuring their biogenic amine content. The biogenic amines detected in commercial anchovy fish sauce were tryptamine, putrescine, cadaverine, tyramine, spermidine, spermine, and histamine. Among them, histamine content was the highest with an average of 1,439.62±812.62 mg/kg. Excessive intake of histamine could result in chemical food poisoning characterized by high blood pressure, headache, and diarrhea. Accordingly, by simulating histamine exposure (repetition=10,000 times) based on the daily intake of 0.969 g of domestic anchovy fish sauce, we found that the estimated average histamine exposure was 24.49±55.48 ㎍/kg bw/day and that the margins of exposure (MOE) value were 139.18 at 1% and 66,141.07 at 95% of 10,000 simulations (9,500 times). As such, it was confirmed that 9,500 out of 10,000 simulations of MOE analysis significantly exceeded MOE 10. Therefore, the risk of exposure to histamine from ingestion of commercial anchovy fish sauce is approximately very low.

• Fire Science and Engineering
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• v.31 no.1
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• pp.18-25
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• 2017

Each country tries to prevent major industrial accidents at industrial sites, such as fire and explosion as well as poisoning incidents, and regulation of the management of chemicals is being enhanced in all sectors. In particular, in the case of laboratories, a variety of chemicals have been developed and handled in accordance with the development of science and technology. On the other hand, the accident probability at laboratories is higher than at industrial sites, because many different kinds of chemicals are handled in the laboratory but in very small amounts and chemical, physical, and biological studies have been carried out in limited spaces. Recently, the accident probability at laboratories was found to be higher as convergence/integration studies were carried out beyond the academic arena. Therefore, in this study, a survey of chemical management was conducted to prevent accidents due to chemicals targeting the laboratory safety coordinator using the FGI (focus group interview) method. The building plan of a chemical management system was suggested based on the results of the survey.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.1
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• pp.78-88
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• 2022

Objectives: To develop the smart sensor to protect worker's health from chemical exposure by adopting ICT (Information and Communications Technology) technologies. Methods: To develope real-time chemical exposure monitoring system, IoT (Internet of Things) sensor technology and regulations were reviewed. We developed and produced smart sensor. A smart sensor is a system consisting of a sensor unit, a communication unit, and a platform. To verify the performance of smart sensors, each sensor has been certified by the Korea Laboratory Accreditation Scheme (KOLAS). Results: Chemicals (TVOC; Total Volatile Organic Compounds, Cl₂: Chlorine, HF: Hydrogen fluoride and HCN: Hydrogen cyanide) were selected according to a priority logic (KOSHA Alert, acute poisoning statistics, literature review). Notifications were set according to OEL (occupational exposure limit). Sensors were selected based on OEL and the capabilities of the sensors. Communication is designed to use LTE (Long Term Evolution) and Wi-Fi at the same time for convenience. Electronic platform were applied to build this monitoring system. Conclusions: Real-time monitoring system for OEL of hazardous chemicals in workplace was developed. Smart sensor can detect chemicals to complement monitoring of traditional workplace environmental monitoring such as short term and peak exposure. Further research is needed to expand the scope of application, improve reliability, and systematically application.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.279-282
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• 2007

When reformer for fuel cell is used, CO in hydrogen gas leads to a seriously decreased membrane electrode assembly (MEA) performance by catalyst poisoning. The effect of CO on performance of modified MEA by sputtering method is studied in this paper. The experimental results show that sputtered Pt and Ru thin film improve a single cell performance of MEA and sputtered metal thin film has a CO tolerance. The air injection process on anode show improved CO tolerance test result. Moreover, Pt, Ru and PtRu thin film by sputtering had influence on the CO tolerance with air injection process.

• Korean Journal of Veterinary Research
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• v.36 no.2
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• pp.471-482
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• 1996

These experiments were undertaken in order to find out the useful clinicopathological diagnostic methods of cadmium poisoning in dogs. Twenty-one dogs were divided into a control group and 6 experimental groups. The experimental groups were adminstered orally 5, 10, 15, 30, 60 and 120mg of cadmium per kg of body weight for 56 days. All dogs were examined for clinical signs, and weekly changes in hematological and blood chemical values. All dogs were necropsied on 57th days of experiment. Tissue samples including hair, skin, muscle, lung, liver, kidney, spleen, pancreas, testis, ovary, uterus, and bone were collected and analyzed for cadmium, zinc, iron and copper contents using atomic absorption spectrophotometer. From these experiments following results were obtained : 1. All experimental dogs showed vomitting, salivation, anorexia, decreased water-intake, dehydration, and marked weight loss. The dogs received 30mg/kg or more of cadmium died during the period from 2nd to 7th week after administration. 2. Hematologically, all experimental dogs showed decrease in erythrocyte count, hemoglobin concentration, and packed cell volume. The anemia was identified as normocytic and regenerative morphologically. 3. No significant differences in serum glutamic oxaloacetic transminase, glutamic pyruvic transaminase, blood urea nitrogen, and cholosterol value were obseved between the control and experimental dogs. 4. The cadmium contents in various tissues of experimental dogs were estimated as $37.8{\sim}201.8{\mu}g/g$ in bone, $14.1{\sim}49.5{\mu}g/g$ in liver, $13.2{\sim}53.1{\mu}g/g$ in kidney, $0.4{\sim}35.2{\mu}g/g$ in pancreas, $0.8{\sim}35.4{\mu}g/g$ in spleen, $0.9{\sim}30.1{\mu}g/g$ in hair, $0{\sim}7.1{\mu}g/g$ in lung, $0{\sim}5.1{\mu}g/g$ in skin, and $0{\sim}3.6{\mu}g/g$ in muscle, respectively. However, the serum, testis, ovary and uterus showed no cadmium accumulation. Two contol dogs showed cadmium accumulation only in bone. 5. Significant differances in zinc, iron, and copper contents in tissue samples were observed between the control and experimental groups.