• Journal of the Korean Society of Safety
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• v.22 no.3 s.81
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• pp.57-64
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• 2007

Recently, the corrosion of concrete structures has received great attention related with the deterioration of sea-side structures, such as new airport, bridges, and nuclear power plants. In this regards, many studies have been done on the chloride attack in concrete structures. However, those studies were confined mostly to the single deterioration due to chloride only, although actual environment is rather of combined type. The purpose of the present study is, therefore, to explore the influences of carbonation and freezing-thawing action to chloride attack in concrete structures. The test results indicate that the chloride penetration is more pronounced than the case of single chloride attack when the carbonation process is combined with the chloride attack. It is supposed that the chloride ion concentration of carbonation region is higher than the sound region because of the separation of fixed salts. Though the use of fly ash pronounces the chloride ion concentration in surface, amounts of chloride ion penetration into deep region decreases with the use of fly ash. The small reduction of relative dynamic elastic modulus induced from freezing-thawing increases the chloride ion penetration depths much. The present study allows more realistic assessment of durability for such concrete structures which are subjected to combined attacks of both chlorides and carbonation or freezing-thawing but the future studies for combined environment will assure the precise assessment.

• Bulletin of the Korean Chemical Society
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• v.18 no.2
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• pp.224-226
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• 1997

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.675-678
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• 1999

Rebar corrosion in concrete containing both chloride ions and calcium nitrite inhibitors were investigated by the various electrochemical methods. Rebar corrosion was accelerated by applying the impressed current to the rebar in concrete. Effect of chloride content and inhibitors on rebar corrosion were evaluated. Accelerated corrosion technique is the method to measure the time to the initiation of cracks of reinforced concretes, by applying constant voltage between rebar and the stainless steel cathedes. The increase of concentration of chloride ions in concrete result in the increase in anodic currents and the reduction of time to crack. However addition of inhibitors did not improve corrosion resistance of rebar in concrete. Rebar corrosion in concrete with chloride ions and inhibitors was also analyzed by the immersed tests though the mesurement of corrosion potentials.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.782-785
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• 2004

Salt attack is one of the serious deterioration factor with respect to the durability of concrete structure. Especially, in case of exposed rebar concrete structure in marine environment, corrosion of rebar is accelerated by penetration of $Cl^-$ from exterior. Through this path, volume of corroded rebar is increased about two and half times due to increased inner pressure originated from rust. As a consequence, the overall deterioration of concrete structure, namely, cracks, reduction of adhesive strength and pop-out is followed. In this paper, the effect of structure treatment of concrete on chloride resistance has been investigated. At the same time, the relationship among several characteristics, such as resistance to chloride, water absorption coefficient and surface hardness of concrete has been investigated. It is believed that surface performance improvement by the application of penetrative hardening agent influences on positively water absorption coefficient, surface hardness of concrete and resistance to chloride ion penetration.

• BMB Reports
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• v.35 no.4
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• pp.409-413
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• 2002

Thioltransferase, also known as glutaredoxin, is an enzyme that catalyzes the reduction of a variety of disulfide compounds. In Schizosaccharomyces pombe, two thioltransferases were reported and the cDNA of one of the thioltransferases (thioltransferase-1) was cloned. Using a Northern blot assay, we investigated the thioltransferase transcription in response to various stress conditions. When the culture was shifted to a high temperature, the thioltransferases transcription was not significantly changed compared to the unshifted $30^{\circ}C$ culture. Treatment of zinc chloride to exponentially-growing cells remarkably increased the thioltransferase transcription, whereas the treatment of mercury chloride greatly reduced the transcription. Treatment of hydrogen peroxide and cadmium chloride caused no significant effects on the transcription of the thioltransferase. These results suggest that the transcription of thioltransferase-1 in S. pombe is induced in response to metal stress that is caused by zinc chloride, but not in response to heat stress or oxidative stress that is caused by hydrogen peroxide.

• Journal of the Korean institute of surface engineering
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• v.32 no.2
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• pp.109-124
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• 1999

A study for replacing methylene chloride for an alternative cleaning agent which can be utilized for cleaning aluminium parts of hard disk drives was carried out at Suwon factory of Samsung Electro-mechanics Co. Ltd. As a result, quite a good cleaning agent was selected through data collection of alternative cleaning agents, their analysis of environment effects and safty factors and testing of their cleaning power. As compared with methylene chloride, the selected cleaning agent has better cleaning power. It is also more environmental-friendly, less toxic and more economical. And the operating cost reduction due to adoption of this alternative cleaning agent in Samsung Electro-mechanics Co. Ltd. was more than ￦l46,000,000 annually without any capital instrument in addition to improvement of environmental and safty conditions in the plant.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.261-264
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• 2005

For concrete structures immersed in seawater, the concentration of chloride used to estimate the chloride diffusion coefficient can be defined as the seawater chloride concentration. However, for seashore concrete structures which are not coming into direct contact with seawater, establishing the interface concentration of chloride becomes delicate. In addition, concrete structures are greatly affected by salt attack primarily due to airborne sea salt like it can be seen through the corrosion of rebar. This study intends to investigate characteristics on the salinity of airborne sea salt by height. Salinity measurement devices were installed at height of 2, 10 and 19m on the seashore water tower located in the area of Samchuk in the Eastern coast. Analysis results of the decrease of salinity with respect to the height above the ground at a distance of 30m from the seashore showed that the reduction reached about 40$\%$ at a height of 10m and 60$\%$ at 20m.

• Korean Journal of Organic Agriculture
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• v.8 no.2
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• pp.89-96
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• 2000

To reduce loss of nitrogen and generation of ammonia gas during composting, poultry manure and sawdust were mixed at the equivalent ratio and calcium chloride, fused superphosphate and vermiculite were added. Ammonia and sulfurous gas during composting, and NH4-N and NO3-N contents of composts were periodically measured. With the treatments of 0.5∼3% calcium chloride and 3% fused superphosphate, ammonia and sulfurous gas during composting significantly decreased, and especially generation of gases sharply reduced and a increase of calcium chlorde. Extractable NH4-N content in composts treasted with calcium chloride and fused superphosphate were high but extractable NO3-N markedly decreased. In conclusion, the results suggest that it is necessary the additon of 1∼3% calcium chloride or 3% fused superphosphate to reduce loss of nirogen and generation of offensive odor during composting of poultry manure mixed with sawdust.

• Carbon letters
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• v.8 no.4
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• pp.280-284
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• 2007

Samples of active carbon of $1150\;m^2/g$ surface area were impregnated with ammoniacal salts of copper, chromium and silver, with and without triethylenediamine. The samples of impregnated carbon were aged at $50^{\circ}C$, with and without 90% RH (relative humidity), for a little more than one year and chemically evaluated periodically. Initially copper (II) and chromium (VI) reduced very fast in the samples in humid atmosphere to the extent of 30% and 60% respectively in four months. These values were found to be unaffected by the presence of triethylenediamine (TEDA) indicating that the chemical did not retard the reduction process of chromium (VI) and copper (II). However, in the absence of humidity the reduction of the impregnants was significantly less (10-12%, w/w) in four months. It was quite evident; therefore, that the moisture was mainly responsible for the reduction of chromium (VI) and copper (II) species in impregnated carbons. The prolonged ageing of the samples with and without triethylenediamme after four months with and without humid atmosphere showed that the extent of reduction of chromium (VI) was very low, i.e. 5-10% and of copper (II) was 2-25%. Silver is not reduced due to carbon, as it remained unchanged in concentration on storage. The impregnated carbon samples (100 g) without triethylenediamine, which were aged at room temperature for 5 years in absence of humidity and unaged when evaluated against cyanogen chloride (CNCl) at a concentration of 4 mg/L and airflow rate of 30 lpm showed a high degree of protection (80- 110 minutes).

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.73-81
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• 2001

The purpose of this study was to determine the adverse effects of methylmercuric chloride(MMC) against the fetal growth and the ossification rate of fetal pectoral and pelvic girdle, stermebrae, ribs and tail in pregnant Fischer 344 rats administered orally on day 7 of gestation. The resulted obtained are as follows. The weight and size of fetus were highly reduced by MMC. The reduction of fetal weight and size were 16. 2%~24.5%(p<0.01), and 34.1%~48.8%(p<0.01), and that of the litter’s weight were 67.0%(p<0.01) and 89.2%(p<0.01) by 20 and 30mg/kg MMC, respectively. Ossification centers were never formed in pectoral and pelvic phalanges and sternebrae, and was reduced as much as 70% in tail by 30mg/kg MMC. And also those were 82.4%~ 91.2%(p<0.01) in ischium, and 52.4~66.7%(p<0.01) in the others(ilium, fenur, tibia, fibula, metatarsals)of pelvic girdle by 30 mg/kg MMC. Ossification of sternebrae was terrible. 5th bone of sternebrae was not ossificated by 20 and 30 mg/kg MMC(p<0.01), and 2nd was also not ossificated by 30 mg/kg MMC(p<0.01).And reduction of ossification rate was 84.8~97.8%(p<0.01) in the others of sternebrae by 30 mg/kg MMC. And then, the reduction of ossification rate was 26.65~49.8%(p<0.01) in fetal ribs by 30 mg/kg MMC, and they were trend to increased as following from center to each edge. In conclusion, it was observed that fetal weight, size, and ossification of each bone were highly significantly reduced by the increased dosage of MMC.