• Fire Science and Engineering
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• v.29 no.4
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• pp.61-66
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• 2015

PVC pipe has excellent corrosion resistance and chemical resistance and is broadly used. However there are no regulations regarding exposed piping material in buildings. There is growing concern about the vulnerability of piping to fires and generating toxic gas. Exposed piping should be made of incombustible materials to prevent spreading of toxic gas and to minimize damage to life and property in case of fire. Many big structures are being built, and concerns regarding damage by fire are continuously growing. In these circumstances, we should reinforce fire safety standards for buildings and heighten safety consciousness to become a well-developed country. For these reasons, we investigated the materials used for exposed piping and the standards of well-developed countries to enhance safety. We tried to figure out the alternatives by examining the actual conditions of each region's buildings. Based on the use of incombustible materials for exposed piping in each region, we tried to enhance the effectiveness for safety by suggesting revisions for related laws and regulations.

• Korean Journal of Materials Research
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• v.10 no.5
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• pp.369-374
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• 2000

In order to investigate the effects of addition of 1M sulfuric acid to the etching solution or 1M hydrochloric acid on the etching behavior of aluminum foil for electrolytic capacitors, the changes in the density of etch pit, the length and diameter of etch tunnels and the capacitance were analyzed using SEM, TEM, LCR meter etc. Sulfate ion as a corrosion inhibitor was contributed to the increase of the surface area comparing with chloride ion. By adding sul-furic acid the density of etch pit and the length of etched tunnel increased and the diameter of the tunnel decreased, resulting in the increase of capacitance. It was also shown that the capacitance decreased when the current density was below $0.9A/\textrm{cm}^2$, while remarkably increased in the other case.

• Journal of Environmental Health Sciences
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• v.29 no.4
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• pp.27-34
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• 2003

Bisphenol A is used in the manufacture of epoxy, polycarbonate, and corrosion-resistant unsaturated polyester-styrene resins required for food packaging materials in industrial processing. Some reports indicated the possibility of harmful effects on rats. In this study was used a method for the determination of bisphenol A in blood according to the OSHA High Performance Liquid Chromatography (HPLC) guideline. The method involved blood extraction using methylene chloride. And it was evaluated developmental and teratogenic effects in pregnant rats and second generation. The results obtained were as follows. There was a significant increase in the body weights and treated groups F1 female in liver, spleen, kidney, but according to dose-response. F1 female rat's relative body weight and absolute body weight are not different. There was a significant increase liver, spleen, kidney organ weight and reproductive organ weight epididymis, prostate gland in F1 male rats. There was a proestrous in pregnant rat, group 200 $\mu\textrm{g}$/kg, 2000 $\mu\textrm{g}$/kg, 20,000 $\mu\textrm{g}$/kg. The effect on rat treated with bisphenol A decrease organ weight and reproductive organ weight. Identification and quantitation were performed with using HPLC C18 column and using at retention time 5.5 min. The results of the detection of bisphenol A were at 20,000 $\mu\textrm{g}$/kg in average 1 $\mu\textrm{g}$/ml, 200 $\mu\textrm{g}$/kg average in 0.9 $\mu\textrm{g}$/ml blood samples. From those results, it could be concluded that the effects of pregnant rat and second generation(F1) by bisphenol A treatment during lactational period were estrogenic and bisphenol A was remained in serum at low level.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.789-792
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• 2008

Recently, the deteriorations of RC bridge decks on express-way are frequently observed. The major cause of deterioration for the RC concrete bridge decks exposed to de-icing chemiclas would be chloride-induced reinforcement corrosion. Therefore, Waterproofing is necessary for improvement of bridge deck durability and comfortable utility. In this study is to investigate the appearance of deterioration and properties of concrete core from the collect in a bridge deck. The results of this study shows that penetration waterproofing agents shows low infiltration depth and low water-repellent. It appears that the damaging of concrete deck is primarily waterproofing system rather than physical property.

• Journal of the Society of Disaster Information
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• v.10 no.4
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• pp.566-571
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• 2014

Recently, with concentrated social and engineering interests on durability, diversified subsequent researches have been progressed. The Chloride-induced corrosion, carbonation, freeze-thaw etc, deterioration factors of concrete act to concrete not privately but complexly, Fly ash is most frequently used admixture which is using a reduction method of deterioration. And the fly ash effects on improvement of durability with enhancement of fluidity, decrease of crack with reduction of hydration heat, promotion of long-age strength and have a economic advantage which replaces cement as a binding material. But, fly ash have different qualities and occasionally reduce the durability and strength by adhesion of AE admixture with unburned carbon powder etc. In this study, the experiments will take about various replacement ratio of fly ash concrete, and will analyze, consider the results, after these will verify applicability and validity as admixture and binding material.

• 보존과학연구
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• s.30
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• pp.63-77
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• 2009

Scientific studies of conservation techniques and materials in Korea have experienced fast development since international practice and academic knowledge have been introduced to Korea from Japan, France, Germany, and etc from the late 1960s. In recent years, it has been observed that the academic standard of research and the level knowledge of the field in Korea at present are far advanced to compete with many countries. However, many Korean cases still have displayed that the standard and the quality of conservation practice need to be improved. This research examined several cases of derelict restoration of metal relics executed by non-conservators and the effects of their ignorant use of irreversible materials on the valuable objects. The purpose of the study is to display the problem of such treatments and to suggest a need of framework to prevent the loss of original form from them. Metal Buddha statue (Cosmic Buddha) in Borim Temple (National Treasure No. 117), which was conserved by an unexperienced non-conservator, has suffered from a serious problem of corrosion because of the use of destructive material, iron chloride. Another case for metal Buddha statue in Dopian Temple (National Treasure No. 63) displays a representative example of using irreversible materials, Cashew and such ignorant application made a later conservation treatment so difficult in removing the material from the surface of the statue. In conclusion, the research argued that the understanding of materials used in the objects, and the value of relics is important, and pre-experiments before applying conservation materials to a valuable heritage are essential in the conservation treatment.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.211-220
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• 2005

The concrete structure is being considered for the main engineered barrier of low and intermediate level radwaste disposal facility. Concrete of low permeability can minimize infiltration of water and effectively prevent release of nuclide to ecosystem. But if concrete degrades, structural stability of disposal structure will decrease while permeability increase, resulting in increased possibility of nuclide release due to water infiltration. Therefore disposal concrete structure degradation shall be minimized to maintain capacity of nuclide isolation. The typical causes of concrete structure degradation are sulfide attack, reinforcement corrosion due to chloride attack, leaching of calcium hydroxide, alkali-aggregate reaction and repeated freezing-thawing. The common cause of these degradation processes is infiltration of water or adverse chemicals into concrete. Based on the study of these degradation characteristics and mechanisms of concrete structure, the methodology of design and service life evaluation of concrete structure as an engineered barrier are reviewed to ensure its long-term durability.

• Computers and Concrete
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• v.6 no.4
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• pp.269-280
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• 2009

In this paper an experimental study of the influence of hot springs curing upon concrete properties was carried out. The primary variables of the investigation include water-to-binder ratio (W/B), pozzolanic material content and curing condition. Three types of hot springs, in the range $40-90^{\circ}C$, derived from different regions in Taiwan were adopted for laboratory testing of concrete curing. In addition, to compare with the laboratory results, compressive strength and durability of practical concrete were conducted in a tunnel construction site. The experimental results indicate that when concrete comprising pozzolanic materials was cured by a hot spring with high temperature, its compressive strength increased rapidly in the early ages due to high temperature and chloride ions. In the later ages, the trend of strength development decreased obviously and the strength was even lower than that of the standard cured one. The results of durability test show that concrete containing 30-40% Portland cement replacement by pozzolanic materials and with W/B lower than 0.5 was cured in a hot spring environment, then it had sufficient durability to prevent steel corrosion. Similar to the laboratory results, the cast-inplace concrete in a hot spring had a compressive strength growing rapidly at the earlier age and slowly at the later age. The results of electric resistance and permeability tests also show that concrete in a hot spring had higher durability than those cured in air. In addition, there was no neutralization reaction being observed after the 360-day neutralization test. This study demonstrates that the concrete with enough compressive strength and durability is suitable for the cast-in-place structure being used in hot spring areas.

• Journal of Environmental Health Sciences
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• v.10 no.2
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• pp.41-51
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• 1984

This study was performed using samples collected at Myungryundong and at Reservoirs. The purpose of this study was to investigate the differences of water quality between tap and raw water, and to analyse drinking water quality by Fe, Zn from corroded galvanized steel pipe. Results were as follows 1. The older the pipe was, the higher the concentration of Ferrum and Zinc was (t-test : p<0.05). Ferrum and Zinc also exceeded the limits in the older galvanized steel pipe. I think that this comes from the corrosion of pipe. 2. Mercury, Arsenic, Cadmium, Lead, Chomium, Argentum and Aurum not detected in raw water were not detected in tap water. Cobalt, Bismuth and Molybudenum detected in raw water were not detected in tap water. I think that this comes from the quality of raw water, the result of water treatment and the improbability of detection of above metals in water delivery system. 3. Silicon measured 2.4698ppm in raw water, but it ranged from 0.4769ppm to 1.982 ppm in tap water. Manganese measured 0.0638ppm in raw water, but it ranged from 0.0026ppm to 0.0198ppm in 17cases(31%) out of 55samples in tap water. I think that this comes from the water treatment. 4. Aluminium not detected in raw water was found in 17 cases (31%) out of the samples (55cases). It may be considered as the use of coagulants $Al_2(SO_4)_3$. $18H_2O$ and PAC (Poly Aluminium Chloride). The concentration of copper in tap water was much higher in 2 cases(3.6%) out of the samples(55) than that of copper in raw water. I think that this may come from the use of ${CuSO}_4$, the preventive of algae growth, and the result of chlorination, but further study must be necoessary to support the proof.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.338-343
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• 2017

In this study, blast furnace slag powder was used in concrete to help reduce carbon dioxide emissions and to recycle industrial waste. Blast furnace slag powder is a byproduct of smelting pig iron and is obtained by rapidly cooling molten high-temperature blast furnace slag. The powder has been used as an admixture for cement and concrete because of its high reactivity. Using fine blast furnace slag powders in concrete can reduce hydration heat, suppress temperature increases, improve long-term strength, improve durability by increasing watertightness, and inhibit corrosion of reinforcing bars by limiting chloride ion penetration. However, it has not been used much due to its low compressive strength at an early age. Therefore, this study evaluates the effects of steam curing for increasing the initial strength development of concrete made using slag powder. The relationship between compressive strength, SEM observations, and XRD measurements was also investigated. The concrete made with 30% powder showed the best performance. The steam curing seems to affect the compressive strength by destroying the coating on the powder and by producing hydrates such as ettringite and Calcium-Silicate-Hydrate gel.