• Analytical Science and Technology
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• v.20 no.3
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• pp.251-254
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• 2007

In this study, a convenient, fast and accurate inductively coupled plasma atomic emission spectrometry (ICP-AES) method has been optimized for the determination of osmium in aqueous solutions. The method makes use of the reaction of sulfurous acid with osmium to quantitative conversion of volatile Os(VIII) to non-volatile Os(IV) in the pH range 2-10. The response was found to be stabilized immediately after sulfurous acid reacted with osmium. The precision was calculated to be 0.5-4.5 % (RSD) under various ICP-AES conditions. The detection limit was 2.5-57.7 ng/g based on $3{\sigma}$ of the blank response (n=3) using a concentric flow nebulization.

• Journal of the Korean Chemical Society
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• v.10 no.2
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• pp.76-90
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• 1966

Ammonium sulfate synthesized by the air oxidation methods without catalyst using the reaction vessel which was fitted with fritted glass at the bottom of it and introducing, through the bottom, ammonia and air with constant flow rates to sulfurous acid solution of constant concentrations at the given temperatures. The experiment showed that the oxidation process was accelerated in accord with the increase of the air flow rates when the ammonia flow rate was constantly kept at ca. 100ml/min. in high temperatures. When the pH of the solution reached 9.0, the oxidation was nearly completed. It is assumed that in the process of reaction, $[O_{2}{\to}HSO_{3}^-]^{\neq}$ would be produced as an activated complex and the reaction was thought to be first order. The experiment indicated that the 0.5M sulfurous solution could be oxidized up to 98.54% at the flow rates of ammonia and air, 100ml/min., and 4l/min., respectively at $50^{\circ}C$.

• Resources Recycling
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• v.17 no.5
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• pp.37-43
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• 2008

Stripping experiments of iron from the loaded Alamine336 by sulfurous, chloric and sulfuric acid solutions have been performed by varying the concentration of acid and stripping conditions. The stripping percentage of iron decreased with the increase of HCl and $H_{2}SO_4$ concentration, while that increased with the increase of $H_{2}SO_3$ concentration up to 3 M. Stripping temperature had adverse effect on the stripping percentage of iron in the stripping by $H_{2}SO_3$ solution, while the stripping percentage of iron by HCl solution increased with the increase of temperature. Stripping isotherm of iron by 0.1 M HCl and 0.1 M $H_{2}SO_4$ solution indicated that three and four stripping stages could result in a solution containing 0.05 M iron at an O/A ratio of 1/10 from the loaded Alamine336 phase where iron concentration was 0.5 M.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.4
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• pp.81-85
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• 2007

A safety valve is used for protecting the pressure vessel and facilities by discharging the operating fluid into the valve from the accident when the pressure is over the designated value. The fluid is sulfurous acid and nitric acid. etc. in the semi-conductor assembly line. Thus the valve elements material must be acid resistance. Teflon, which is used generally as inner parts of a valve, tends to easily sticks to sliding surface by thermal expansion under high temperature. Some studies are performed to change teflon to another material and shape to have a better fluidity under the condition. The analysis of the thermal expansion is conducted by commercial FEM software to improve the problems. Boundary conditions were temperature and load in this study. From the analysis, the thermal expansion of stainless steel is verified to be lower than that of teflon under high temperature. Thus coupled teflon/stainless steel-made valve is applied to assembly line without danger due to thermal expansion.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2109-2113
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• 2014

Solvent extraction of Fe(III) from chloride solution by using a mixture of D2EHPA (Di-(2-ethylhexyl)-phosphoric acid) and TBP (Tri-butyl phosphate) and the reductive stripping of Fe(III) from the loaded organic were investigated. Quantitative extraction of Fe(III) from the solution (Fe concentration = 90 g/L) was accomplished in two cross-current extraction stages by using the mixture of D2EHPA and TBP. In order to facilitate the stripping efficiency, a reductive stripping method was employed by using $H_2SO_3$ or $Na_2SO_3$ as a reducing agent. The addition of $H_2SO_4$ into reducing agents led to improvement in the stripping efficiency while high concentration acid would suppress it. Both of the mixtures of $H_2SO_4+H_2SO_3$ and $H_2SO_4+Na_2SO_3$ showed good efficiency for the stripping of Fe(III), while the latter was recommended as the stripping solution based on the economics and experimental condition.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1581-1584
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• 2007

The safety valve is the important equipment used to protect the pressure vessel and pressure facilities from overpressure by discharging the operation medium when the pressure of system is reaching the design pressure of the system. Some materials for a safety valve disk are studied in this paper. A studied safety valve has to resist sulfurous acid and nitric acid. etc. Furthermore teflon which is a general material of the valve easily sticks to a disk and a sliding part of the valve by thermal expansion. Therefore both teflon and stainless-steel are used to improve these problems. The analysis of the thermal expansion is conducted with commercial FEM software to improve the problems. Boundary conditions were temperature and load in this study. From the analysis, the thermal expansion of by teflon/stainless steel-made valve is lower than that of teflon-made valve under high temperature. Thus, teflon/stainless steel-made valve is safe and no malfunction by thermal expansion.

• Environmental and Resource Economics Review
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• v.11 no.2
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• pp.261-278
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• 2002

Based on the hedonic pricing method, this paper investigates the effect of air quality on the apartment price in Seoul. The empirical results show that both the structural variables such as years of construction, heating system, and size of apartment complex and accessability variables such as distances to subway station and parks provide statistically significant effects on the price of apartment, Especially, the dendity of sulfurous acid gas ($SO_2$) and ozone ($O_3$) in the air, indicating air quality, negatively affect the price of apartment, This implies that as the condition of air quality to become worse, apartment price decreases, Therefore, when the degree of aversion of apartment residents against the air pollution affects the formation of apartment's market price, the MWPT(Marginal Willingness to Pay) in order to improve the air quality 10% has been estimated as 36,000~39,000Won per month.

• Journal of Korean Society of Forest Science
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• v.55 no.1
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• pp.37-46
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• 1982

These studies were carried out to know the measure of damage having an effect on the ornamental trees owing to sulfurous acid gas($So_2$) which injures much forest trees among air pollutions in south area of Korean and to know the difference of smoke resistance on the five representative species among them and therefore to establish the preventive measure of air pollutions in industrial complex of south area of Korea by the ornamental trees. The reaction formula utilized was $Na_2So_2+H_2So_4$ $Na_2So_4+H_O+So_4$. The results obtained were as follows. 1) The ornamental trees surveyed in the industrial complexes of Ul-San, Chang-Won and Po-hang belonged to 51 species, 161,699 trees in all. The most five species among 51 sorts of woody plants were Populus tomentiglandulosa, Buxus microphylla, Forsythia korenan, Juniperus chinensis and Pinus densiflora. 2) The relation between the concentration of sulfurous acid gas($So_2$) and the damage rate upon investigation in each species: In case of low concentration the destructive quantities of cells of woody plants, and the more increased the concentrations, the more increased the amount of damage. 3) The difference of smoke resistance among five species showed to be the strongest in Buxus micorphylla, the second rand Pupulus tomentiglandulosa, the third rand Forsythia koreana, the fourth rank Juniperus chinensis and the weakest in Pinus densiflora. 4) The ornamental trees of industrial complex expecially in south area of Korea in future should be planted gradually broad-leaved trees which have strong sprout, smoke resistance and thick leaved rather than comifers. 5) I think that the area of city forest in industrial complex requires about $50m^2$ per head of population and about 100m width of green belt between industrial area and residential district.

• Journal of Forest and Environmental Science
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• v.17 no.1
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• pp.88-103
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• 2001

It is one of the important tasks to accurately grasp features of the devastated land to revegetate the denuded, volcanic land. In the present report three factors of such features were discussed : the ash fall phenomenon the overflow of surface water, and the generation of sulfurous acid gas, which are all usual, harmful factors for the successful growth of introduced plants to such area. In addition, it is indicated that to overcome those harmful factors some artificial tools should be applied in such regions before the introduction of pioneer tree species such as Pinus thunbergii and etc. In our three-year pilot study it is found out that the use of mulching sheets developed originally by research members combined together with symbiotic microorganisms such as Pisolithus tinctorus Coker et Couch f. tinctorius was very effective. Experimental plots surveyed throughly in Mt. Fugendake in Nagasaki Prefecture and Mt. Sakurajima in Kagoshima Prefecture showed successful revegetation as models. Finally, for the revegetation of the denuded, volcanic land it is recommended that mulching sheets should be used together with symbiotic microorganisms.

• Korean Journal of Environment and Ecology
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• v.15 no.3
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• pp.276-285
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• 2001

This report surveyed degradation of forest environment and rehabilitation in Ashio of Japan. Since 1880, a large scale forestry in this area has been destroyed by sooty smoke, and the local government invested heavily to rehabilitate the damaged forestry and denuded mountains. These degradations are due to complex operations, such as sulfurous acid gas from copper refinery, forest fires, steep slope and disadvantageous climate. The rehabilitation works on degraded forestry(2,399ha) were undertaken by tree planting fur three years from 1897. However, forest degradation and disasters were continued, and the total damaged areas were about 2,400~3,000ha in 1956. A Manual labor method, a Helicopter method and also Combination of manual labor and helicopter method had been adopted to rehabilitation works from 1945 to 1996, while 828.19ha of the degraded mountains was rehabilitated. Total investment for those projects was 80 billion yen. A debris control dam, a soil arresting structure, a vegetation-block, a vegetation sack measures and tree planting have implemented significantly fur the method of rehabilitation. An objective of manual labor works is a complete rehabilitation on each place through 3 stage working. The revived green areas accounted fur 49% of the total, and the entire afforest areas are less than 10%. In coming 25 years, an amount of 21.3 billion yen will be invested to rehabilitate 564ha of degraded mountain lands. However, it is impossible to estimate that how long it will take until the whole degraded mountain lands are completely rehabilitated. Rehabilitation works in Ashio may be applicable to environmental restoration and revegetation in the abandoned coal-mine lands of Korea.