• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.68-78
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• 2006

In the past few years, considerable efforts have been directed towards the further development of Urea-SCR(selective catalytic reduction) technique for diesel-driven vehicle. Although urea possesses considerable advantages over Ammonia$(NH_3)$ in terms of toxicity and handling, its necessary decomposition into Ammonia and carbon dioxide complicates the DeNOx process. Moreover, a mobile SCR system has only a short distance between engine exhaust and the catalyst entrance. Hence, this leads to not enough residence times of urea, and therefore evaporation and thermolysis cannot be completed at the catalyst entrance. This may cause high secondary emissions of Ammonia and isocyanic acid from the reducing agent and also leads to the fact that a considerable section of the catalyst may be misused for the purely thermal steps of water evaporation and thermolysis of urea. Hence the key factor to implementation of SCR technology on automobile is fast thermolysis, good mixing of Ammonia and gas, and reducing Ammonia slip. In this context, this study performs three-dimensional numerical simulation of urea injection of heavy-duty diesel engine under various injection pressure, injector locations and number of injector hole. This study employs Eulerian-Lagrangian approach to consider break-up, evaporation and heat and mass-transfer between droplet and exhaust gas with considering thermolysis and the turbulence dispersion effect of droplet. The SCR-monolith brick has been treated as porous medium. The effect of location and number of hole of urea injector on the uniformity of Ammonia concentration distribution and the amount of water at the entrance of SCR-monolith has been examined in detail under various injection pressures. The present results show useful guidelines for the optimum design of urea injector for reducing Ammonia slip and improving DeNOx performance.

• YAKHAK HOEJI
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• v.57 no.6
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• pp.420-425
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• 2013

Phentermine (PT) and phenmetrazine (PM) have been widely used as anti-obesity drugs. These drugs should be used with caution due to its close relation to amphetamine in its structure and toxicity. PT and PM, amphetamine-type anorectics, have recently been considered as alternatives for methamphetamine abuse in Korea. In addition, the misuse and abuse of PT and PM obtained by illegal sources such as the internet become a serious social problem. In the present study, a simultaneous detection and quantification method for determining PT and PM in human urine was developed and validated according to the international guidelines. The urine samples were screened using a fluorescence polarization immunooassay and analyzed by gas chromatography mass spectrometry (GC-MS) after extraction using automatic solid phase extraction (SPE) with a mixed-mode cation exchange cartridge and derivatization with pentafluoropropionic anhydride (PFPA). The validation results for selectivity, linearity, limits of detection (LOD) and quantification (LOQ), intra- and inter-assay precision and accuracy and recovery were satisfactory. The validated method was successfully applied to authentic urine samples collected from 38 drug abuse suspects. PT and/or PM were identified with or without methamphetamine in urine samples. Abuse of PT and PM have increased continuously in Korea, therefore, closer supervision of the inappropriate use of anoretics is necessary.

• Journal of Animal Science and Technology
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• v.64 no.4
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• pp.603-620
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• 2022

Human activities have caused an increase in greenhouse gas emissions, resulting in climate change that affects many factors of human life including its effect on water and food quality in certain areas with implications for human health. CH₄ and N₂O are known as potent non-CO₂ GHGs. The livestock industry contributes to direct emissions of CH₄ (38.24%) and N₂O (6.70%) through enteric fermentation and manure treatment, as well as indirect N₂O emissions via NH₃ volatilization. NH₃ is also a secondary precursor of particulate matter. Several approaches have been proposed to address this issue, including dietary management, manure treatment, and the possibility of inhibitor usage. Inhibitors, including urease and nitrification inhibitors, are widely used in agricultural fields. The use of urease and nitrification inhibitors is known to be effective in reducing nitrogen loss from agricultural soil in the form of NH₃ and N₂O and can further reduce CH₄ as a side effect. However, the effectiveness of inhibitors in livestock manure systems has not yet been explored. This review discusses the potential of inhibitor usage, specifically of N-(n-butyl) thiophosphoric triamide, dicyandiamide, and 3,4-dimethylpyrazole phosphate, to reduce emissions from livestock manure. This review focuses on the application of inhibitors to manure, as well as the association of these inhibitors with health, toxicity, and economic benefits.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.108-115
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• 2023

Although hydrazine is an excellent liquid propellant, caution is required during storage and handling due to its high toxicity and reactivity. Safety guidelines should be established in consideration of the chemical reactivity by unintended leakage. In this study, the status of hydrazine facilities at launch site and safety standards for storing and handling were investigated and then, the reactivity between chemicals and hydrazine was analyzed. As a result of the analysis, hydrazine has reactivity with the exception of fuel oil. This paper emphasizes the imperative nature of constructing a dedicated hydrazine storage facility. Ensuring compatibility between hydrazine and the materials used in storage containers and handling equipment is crucial to prevent undesired reactions that could compromise safety. It was intended to be used as basic data to secure the range safety when handling hydrazine.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.73-84
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• 2024

In this study, a quantitative risk impact assessment is performed using an ALOHA program to identify the risks when applying ammonia as fuel for combined cycle power plants as one of the solutions of climate change. The worst and the alternative accident scenarios are established for the Sejong combined cycle power plant and the effective ranges are calculated in terms of flammability, thermal radiation, overpressure and toxicity. The analysis results show that the toxic risk is the most critical and the effective distance is highly proportional to the mixing ratio of natural gas and ammonia by showing the Pearson's correlation coefficient over 98% as 0.991, 0.987 and 0.989 for the Level Of Concern(LOC)-1, LOC-2 and LOC-3, respectively. In addition, the coefficients of linearity for LOC-1, LOC-2 and LOC-3 are calculated to 133, 70 and 29, respectively so it can be confirmed that the effective distance increases as the criterion decreases.

• Corrosion Science and Technology
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• v.8 no.5
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• pp.197-202
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• 2009

The high toxicity of wax, oil, varnish and volatile corrosion inhibitor(VCI) corrosion inhibitors lead to an increasing interest in using non-toxic alternatives such as anti-corrosive film. This study aims to investigate the possibility to use acryl based anti-corrosive film as a substitution of toxic corrosion inhibitors. Acryl emulsions were polymerized by several acryl monomers(acrylonitrile(AN), n-butyl acrylate(nBA), methylmethacrylate(MMA) and glycycyl methacrylate(GMA)), non-toxic corrosion inhibitor, crosslinking agents(diethylene glycol dimethacrylate(DEGDA)) and various additives in order to apply substrate of anti-corrosive film. Acryl emulsion for anti-corrosive film(AeACF) as a substrate of corrosion inhibitor film has excellent removal characteristic at above $25^{\circ}C$. The crosslinked by DEGDA in a range of above 4 wt% content anti-corrosive film can easily remove from the metal surface by using hands because it kept a balance of cohesion and adhesion strength. Anti - corrosive performance of AeACF is better than anti-corrosive oil by corrosion rate test, which was measured $54.3mg/dm^2$ day(MDD) and $142.9mg/dm^2$ day, respectively. Anti-corrosive film consisting of acryl monomers and inorganic anti-corrosive ingredients did not emit any toxic pollutants by gas chromatography. Thus it is estimated that acryl based anti-corrosion film can substitute toxic corrosion inhibitors.

• Fire Science and Engineering
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• v.15 no.3
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• pp.36-43
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• 2001

Several types of widely used interior upholsteries including wallpaper, veneer board and floor cover, were selected to be evaluated by using the method of NES 713 text. Test results indicates that a fire with retardant wallpaper release a large amount of toxic gases when constantly exposed to a fire source. When evaluated in terms of the masses of released gases, the release of Carbon monoxide appears the highest in case of wallpaper fire, while the ratio of CO/Mass loss appears the highest in case of floor cover fire. Therefore, it can be concluded that, a large amount of toxic gas will release from a floor cover fire with even a small quantity of fuel.

• Journal of Applied Biological Chemistry
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• v.56 no.2
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• pp.109-112
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• 2013

Azole fungicides are one of the most wide-spread antifungal compounds in agriculture and pharmaceutical applications. Their major mode of action is the inhibition of ergosterol biosynthesis, giving depletion of ergosterol, precursors and abnormal steroids. However, metabolic consequences of such inhibition, other than steroidal metabolitesare not well established. Comprehensive metabolic profiles of Saccharomyces cerevisiae has been presented in this study. Wild type yeast was treated either with glucose as control or azole fungicide (ketoconazole). Both polar metabolites and lipids were analyzed with gas chromatography-mass spectrometry. Approximately over 180 metabolites were characterized, among which 18 of them were accumulated or depleted by fungicide treatment. Steroid profile gives the most prominent differences, including the accumulation of lanosterol and the depletion of zymosterol and ergosterol. However, the polar metabolite profile was also highly different in pesticide treatment. The concentration of proline and its precursors, glutamate and ornithine were markedly reduced by ketoconazole. Lysine and glycine level was also decreased while the concentrations of serine and homoserine were increased. The overall metabolic profile indicates that azole fungicide treatment induces the depletion of many polar metabolites, which are important in stress response.

• Journal of ILASS-Korea
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• v.17 no.2
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• pp.64-70
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• 2012

Water mist fire suppression systems which use relatively small droplets of water with high injection pressure are increasingly being used in wider applications because of its greater efficiency, low flooding damage and low toxicity. However, the performance of the system significantly relies on the water mist characteristics and it requires better understanding of fire suppression mechanism of water mist. In the present study, computational fluid dynamics simulations were carried out to investigate cooling performance of water mist in heated chamber. The gas phase was prepared with natural convection heat transfer model for incompressible ideal case and then the effects of water mist injection characteristics on cooling capabilities were investigated upon the basis of the pre-determined temperature field. For the simulation of water mist behavior, Lagrangian discrete phase model was employed by using a commercial code, FLUENT. Smaller droplet sizes, greater injection angles and higher flow rates provided relatively higher cooling performance.

• Journal of Environmental Health Sciences
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• v.27 no.4
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• pp.85-91
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• 2001

The regulation of Material safety data sheets(MSDS) was required for the chemicals in use in the workplace from July 1976. Under the provisions of the workplace hazardous materials information system, employers in Korea must be provided with accurate and comprehensive MSDS. To examine the reliability of MSDS for organic solvents, 63 organic solvents and MSDS were collected from the workplace of 39 companies located in Kyonggi province. Manufacture\`s MSDS were compared with the actual composition of the collected samples, and further examined the reliability by checking whether the chemicals analyzed were included in the MSDS correctly. 38 solvents were able to analyze their composition by gas chromatography-mass selective detector(GC-MSD). Among them, 28 solvents were incorrect in their composition and contents. In some case, health hazardous or carcinogenic chemicals which were not included in the MSDS were detected from samples. As a result of evaluating whether the MSDS correspond to the regulation required by Industrial Safety and Health Act (ISHA), the information in the MSDS including hazard classification, occupational exposure level, toxicity, regulatory information were incorrectly provided, and some MSDS did not disclose carcinogenic in their MSDS, and some MSDS were not written in the standard format. From this survey, continuous monitoring and promoting correct MSDS, and analyzing the components of the solvents were required to endure the reliability of MSDS for organic solvents.