• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.11a
• /
• pp.252-255
• /
• 1996

Cl-based gas chemistry is generally used to etching for Al alloy metallization. After the etching of Al alloy with Cl-based gas plasma, residual chlorine on Al alloy reacts with $H_2O$ due to air exposure and results in Al corrosion. In this study, the corrosion Phenomena of Al were examined with XPS(X-ray photoelectron spectroscopy) and SEF(Scanning electron microscopy). It was confirmed that chlorine mainly existed at the grain boundary of Al alloy after plasma etching of Al alloy with Cl-based gas chemistry and Al corrosion was largely generated at the grain boundary of Al a1loy. And residual chlorine was passivated by sulfur and fluorine which were generated by SF$_{6}$ plasma. These effects of passivation reduced the Al corrosion due to air exposure.e.

• Journal of Korea Society of Waste Management
• /
• v.34 no.5
• /
• pp.468-473
• /
• 2017

This study was carried out to examine the characteristics of hydrogen sulfide adsorption using an iron hydroxide-based adsorbent. The prepared adsorbent was discussed with regard to its adsorption capacity and analyzed via surface analysis methods to illustrate the physical characteristics of hydrogen sulfide adsorption. As the drying temperature increased, the adsorption capacity of the adsorbent decreased from 29.15wt% to 22.73wt%. The adsorption capacity was decreased as the space velocity increased and showed an adsorption capacity of about 3.65 at $3,157.6h^{-1}$. The effect of sulfur dioxide was to decrease the adsorption capacity from 29.15wt% to 27.94wt%. The adsorbent exhibited the amorphous type in its physical appearance based on XRD and EDS analysis.

• Tribology and Lubricants
• /
• v.20 no.5
• /
• pp.231-236
• /
• 2004

Sulfur Hexafluoride, S $F_{6}$ is widely used for leak detection and as a gaseous dielectric in transformers, condensers and circuit breakers. S $F_{6}$ gas is also effective as a cleanser in the semiconductor industry. This paper presents a numerical study of the sealing force of disk type seal in S $F_{6}$ gas safety valve. The sealing force on the disk seal is analyzed by the FEM method based on the Taguch's experimental design technique. Disk seals in S $F_{6}$ gas safety valve are designed with 9 design models based on 3 different contact length, compressive ratio and gas pressure. The calculated results of Cauchy stress and strain showed that the sealing characteristics of Teflon $^{ }$PTFE is more effective compared to that of FKM(Viton), which is related to the stiffness of the materials. And also, the contact length of the disk seal is important design parameter for sealing the S $F_{6}$ gas leakage in the safety valve.afety valve.

• Journal of the Korean Ceramic Society
• /
• v.48 no.1
• /
• pp.52-56
• /
• 2011

Silicon carbide (SiC) is a candidate material for heat exchangers for VHTR (Very High Temperature Gas Cooled Reactor) due to its refractory nature and high thermal conductivity. This research has focused on demonstration of physical properties and mock-up fabrication for the future heat exchange applications. It was found that the SiC-based components can be applied for process heat exchanger (PHE) and intermediate heat exchanger (IHX), which are operated at $400{\sim}1000^{\circ}C$, based on our examination for the following aspects: optimum fabrication technologies (design, machining and bonding) for compact design, thermal conductivity, corrosion resistance in sulfuric acid environment at high temperature, and simulation results on heat transferring and thermal stress distribution of heat exchanger mock-up.

• Journal of Environmental Science International
• /
• v.26 no.9
• /
• pp.1073-1080
• /
• 2017

Manufacturing and technology industries produce large amounts of air pollutants. Ulsan Metropolitan City, South Korea, is well-known for its large industrial complexes; in particular, the concentration of $SO_2$ here is the highest in the country. We assessed $SO_2$ monitoring sites based on conditional and joint entropy, because this is a common method for determining an optimal air monitoring network. Monthly $SO_2$ concentrations from 12 air monitoring sites were collected, and the distribution of spatial locations was determined by kriging. Mean absolute error, Root Mean Squared Error (RMSE), bias and correlation coefficients were employed to evaluate the considered algorithms. An optimal air monitoring network for Ulsan was suggested based on the improvement of RMSE.

• Ocean and Polar Research
• /
• v.22 no.1
• /
• pp.1-13
• /
• 2000

Chemoautotrophic symbiotic bacteria of organisms inhabiting the hydrothermal vent and cold seep communities in the deep-sea were histologically examined using a transmission electron microscopy on symbionts of Calyptogena sp. A from the site east off Miyako (water depth at 1,700m), Calyptogena sp. B from the Calyptogena Site, vestimentiferan tube worm Lamellibrachia sp. A from Sagami Bay Lamellibrachia sp. B from Calyptogena Site of the Iheya Ridge, pogonophoran tube worms from Sagami Bay and Calyptogena Site of the Iheya Ridge, Bathymodiolus spp. from Sagami Bay, the Iheya Ridge and the North Fiji Basin. Based on the morphological microscopic observations, two species of Calyptogena from Miyako and the Iheya Ridge, two species of vestimentiferan tube worms from Sagami Bay and the Iheya Ridge, and pogonophoran tube worms from Sagami Bay and the Iheya Ridge observed to host sulfur-oxidizing symbiotic bacteria. The occurrence of chemosynthetic symbionts in these organisms was expected beforehand based on the ecological observations of their habitats. Other members of these groups from the world oceans, and the recent advances in the symbiosis at vents and seeps were reviewed.

• Korean Journal of Environmental Agriculture
• /
• v.6 no.2
• /
• pp.53-65
• /
• 1987

The study was performed to investigate the effect of gaseous emissions of sulfur dioxide and hydrogen fluoride on the growth of rice plants under stressed field conditions consisting of 88 industrial plants operating with 285 smoke stacks emitting pollutants. As for the relationship between yields and yield components it is believed that the panicles per hill is the single most important component affecting the rate of yield of the rice plant. Based on the standard partial regression coefficient analysis, panicles per hill has the largest contribution to yield and the average contribution of 54%. Other components such as spikelets per panicle, percent fertility and 1000 grain weight are also contributing factors to yield, although far less so. Fluorine content in the leaf appear to have more negative effect on panicles per hill, percent fertility and subsequent overall yield than does sulfur content in the leaf. It is constantly observed and interesting to note that fluorine and sulfur content in the leaf appears to have no effect on spikelets per panicle and 1000 grain weight. Reduction in yield seems to be affected mainly by panicles per hill which are, in turn, affected more by fluorine content in the leaf as demonstrated by the standard partial coefficient analysis. Regarding the prediction sum of the square of the regression equation, the lowest value was found when nine variables were used for the analysis. The variables taken into consideration were the monthly sulfur and fluorine content in the leaf as well as the monthly percent of leaf damage during the months of June, July and August. A significant correlation is found between the actual and predicted yields by the regression equations selected as a result of a prediction sum of the square analysis.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.1
• /
• pp.21-28
• /
• 2009

Physico-chemical characteristics of the Ca-based and Na-based dry sorbents were compared using thermo-gravimetric analysis (TGA) and temperature programmed desorption (TPD) methods. The studied characteristics were thermal stability, sulfur dioxide ($SO_2$) absorption capacity and absorption rate at $250^{\circ}C$ which is a typical temperature before a fabric filter, and $SO_2$ absorption capacity at an ambient temperature. Calcium hydroxide ($Ca(OH)_2$) started to decompose into calcium oxide (CaO) at $390^{\circ}C$ and completed at 480~$500^{\circ}C$, showing 76% of an original $Ca(OH)_2$ weight. Sodium bicarbonate ($NaHCO_3$) also converted to sodium carbonate ($Na_2CO_3$) between $95^{\circ}C$ and $190^{\circ}C$, decreasing the weight to 63% of its initial weight. Among four sorbents tested at $250^{\circ}C$, sodium carbonate had the highest capacity, absorbing 0.35 g $SO_2$/g sorbent. Calcium oxide and calcium hydroxide followed that showing 0.156 g and 0.065 g $SO_2$ absorption per absorbent respectively. Ca-based absorbents showed slower rate than sodium carbonate because of initial stagnant step. However, calcium hydroxide caught more $SO_2$ than sodium carbonate at ambient temperature. From this work, it can be concluded that Ca-based absorbent is a proper sorbent for $SO_2$ treatment at low temperature and sodium carbonate, at high temperature.

• Particle and aerosol research
• /
• v.13 no.2
• /
• pp.43-52
• /
• 2017

Policy direction for the management of air quality in Korea has been on the reduction of the average concentrations of the criteria air pollutants such as sulfur dioxide and fine particles. However, recently, risk based management of air pollutants becomes an important issue. In this study, to develop an effective air quality management policy direction in Korea, (1) the fourth Multiple Air Toxics Exposure Study (MATES IV) carried out in the South Coast Air Quality Management District (SQAQMD) in the USA is reviewed and (2) the results are compared with in these in Seoul and (3) policy directions are suggested. It was found that (1) systematic integrated study comprising of measurement, modeling, emission inventory estimation, and risk assessment was essential to estimate the health risk of air pollutants reliably, (2) cancer risk of diesel particle was dominant over other air pollutants, and (3) health risk based emissions were different from amount based emissions. It was suggested that (1) reducing the exposure from hot spots might important to reduce health risk from air pollutants and (2) an integrated air quality management administration system is important for the efficient management of air pollution.

• Analytical Science and Technology
• /
• v.28 no.3
• /
• pp.175-181
• /
• 2015

Cyantraniliprole, which is an ananthranilic diamide insecticide that was developed by the DuPont Corporation, was registered in the Republic of Korea in 2012. It offers exceptional insecticidal activity on a broad range of Lepidopera, Coleoptera, Diptera, and Isoptera. The maximum residue limits are set to pepper, peach, apple, sweet pepper, welsh onion, and so on (0.2~2.0 mg/kg). Therefore, an analytical method for determining cyantraniliprole residue in agricultural products was developed to ensure food safety. In previous studies, welsh onions were among vegetables included in the allium species, which is a representative plant with sulfur organic compounds. In this study, the analytical method was developed and evaluated for the elimination of sulfur compounds from the test solution of allium species during pesticide residue analysis. In order to inactivate the enzyme allinase and produce sulfur compounds, sample extraction was made in the base state pH 10 by reducing the activity of the enzyme. The recoveries of the developed method ranged from 81.9% to 83.2%, and the relative standard deviations were less than 10%. Therefore, based on the results, the method developed in this study is accurate and appropriate for use in cyantraniliprole determination. It will be used as the official method for managing the safety of cyantraniliprole residues in agricultural products.