• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.23-28
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• 2024

Cesium is a potential toxic contaminant due to its high solubility, which allows it to easily penetrate the human body and potentially induce cancer or DNA mutations. In this study, oxygen functional groups were introduced on activated carbons (ACs) by ozone treatment to enhance the cesium adsorption capacity. As the ozone treatment time increased, the oxygen content on the ACs surface increased. Subsequently, the electrostatic interaction between ACs and cesium enhanced, resulting in higher cesium ion adsorption efficiency across all samples. In particular, the sample treated with ozone for 7 minutes at an internal ozone concentration of 50000 ppm had roughly 12% greater oxygen functional group content and the highest cesium removal effectiveness (97.6%). Meanwhile, samples treated for 5 minutes showed a 0.3% cesium removal rate difference compared to those treated for 7 minutes, which was caused by the surface chemical similarity of the two samples due to the reactive characteristics of ozone gas. However, the cesium adsorption performance of ozonated activated carbon seems to be mainly influenced by the amount of oxygen functional groups introduced to the surface, although the specific surface area and pore structure of the activated carbon are also important.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.182-190
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• 2009

Statement of problem: Microleakage at the occlusal and gingival margin of Class V cavities restored with composite resin has traditionally been considered an obstacle to successful restoration. Purpose: The aim of this study was to assess the effectiveness of three different surface sealants(Fortify, Permaseal and Biscover LV) on the marginal sealing of Class V light-activated composite resin restorations(Z250). Material and methods: Forty noncarious human premolars and molars extracted within a three-month period were selected. Class V cavities with the occlusal margin in enamel and gingival margin in cementum were prepared in both buccal and lingual surfaces. The teeth, randomly assigned in four groups with twenty cavities in each group, were restored with composite resin after applying an adhesive system(Clearfil SE bond). After the finishing and polishing procedures, the restorations were covered with a specific surface sealants, except for the control samples, which were not sealed. After placing restorations, the specimens were thermocycled, and immersed in a 2% methylene blue solution for twenty four hours and sectioned longitudinally. The marginal microleakage was evaluated at the occlusal and gingival interfaces using a microscope and compared among the four groups using ANOVA test and Wilcoxon Rank-Sum test($\alpha$=0.05). Results: Statistical analysis showed that there was significantly less leakage when the surface sealants were used than there was in control group(P<.05). There were no significant differences of microleakage at occlusal and gingival margins among groups. There were no significant differences between microleakage of occlusal and gingival margins in each group. Fortify was not statistically different from control group at the gingival margin(P>.05). Conclusion: Application of surface sealants was an effective method of surface coating in reducing microleakage at occlusal and gingival margins of Class V composite resin restorations. However, it is certain that some microleakage still occurred despite the application of surface sealants, especially gingival margins.

• Fire Science and Engineering
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• v.34 no.2
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• pp.147-155
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• 2020

This paper presents a study on the development of a fire extinguishing agent and extinguishing system for an energy storage system (ESS) fire. The fire extinguishing agent designed to extinguish an ESS fire is a highly permeable fire extinguisher that reduces the surface tension and viscosity while bringing about cooling action. This is the main extinguishing effect of this type of wetting agent, which displays the characteristics of fire extinguishing agents used for penetrating the battery cells inside the ESS module. For the fire extinguishing system, a local application system was designed to suppress fire on a rack-by-rack basis. A 360° rotating nozzle was inserted into the rear hall of the ESS module, and general nozzles were installed in the rack to maximize the fire extinguishing effect. The fire extinguishing agent was strongly discharged by virtue of the gas release pressure. Experiments on fire suppression performance with ESS module 1 unit and module 3 units showed that all visible flames were extinguished in 8 s and 9 s, respectively, by the fire extinguishing agent. In addition, based on confirming reignition for 600 s after the fire extinguishing agent was exhausted, it was confirmed that the ESS fire was completely extinguished without reignition in all fire suppression performance experiments.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.85-93
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• 2011

This study experimented to evaluate the environment friendly high performance ternary cement concrete deck overlay pavement using mineral admixture such as fly ash and ground granulated blast-furnace slag. It was measured to find best binder mixing according to replacement rate of mineral admixture with compressive strength and flexural strength. After finding best binder, it is also experimented to evaluate durability on chloride penetration resistance, freezing- thawing resistance, scaling resistance of deicing chemicals, abrasion resistance, alkali-silica reactivity test and bonded environment friendly high performance ternary cement concrete deck overlay pavement experimented to evaluate bonded old deck and new concrete overlay pavement using special polymer cement mortar. In additions, bonded environment friendly high performance ternary cement concrete deck overlay pavement by experimental construction was evaluated at interchange bridge of North Yeoju. Result, examination was indicated better binding with binder replacement of cement 70%, ground granulated blast-furnace slag 15% and fly ash 15%. And special polymer cement mortar used in old deck and new overlay concrete was indicated better bonding both laboratory and construction.

• Journal of Conservation Science
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• v.20
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• pp.89-103
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• 2007

The bedrock beneath the Chokseongnu pavilion consists of sandstone with alternate dark-gray to light-brown siltstone and dark-gray shale of the Jinju Formation, where bedding is well developed toward the Chokseongmun gate. Large to small joints and overbreak from the erosion weathering have been developed in the bedrock. Besides, water leakage from development of discontinuity planes, fragmentation of shale, crack and joint by tree roots are observed on the bedrock. While shale and siltstone showed high sensitivity in physical and chemical weathering, respectively, sandstone indicated the highest weathering sensitivity in both. As the results of structural stability analysis, the whole bedrock has high instability in wedge failures, and especially section No. II slope is more instable than section No. I. Therefore, it is necessary for the bedrock to be strengthened by improvement method for soft foundations and the surface reinforcement. The trees causing mechanical collapse of the bedrock should be also removed and a water flow prevention measure or a water exhaust are required.

• KSBB Journal
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• v.24 no.1
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• pp.80-88
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• 2009

Human prostatic acid phosphatase (PAP), with comprehensive homology to glandular kallikrein, are representative serum biomarkers of prostate cancer. Dendritic cell (DC), which is the potent antigen-presenting cells(APC) in the immune system, can induce strong T cell responses against viruses, microbial pathogens, and tumors. Therefore, the immunization using DC loaded with tumor-associated antigens is a powerful method for inducing anti-tumor immunity. The CTP (Cytoplasmic Transduction Peptide) technology developed by Creagene which can transport attached bio-polymers like nucleic acids or proteins into the cell with high permeation efficiency. As the active forms of PAP can mediate apoptotic processing, we used multimer forms of PAP as an inactive form for antigen pulsing of DCs. In this study, multimeric forms of CTP-rhPAP was obtained according to the advanced purification process and subsequently confirmed by gel filtration chromatography, western blot and Dynamic Light Scattering. Therefore, CTP-conjugated PA multimers transduced into the cytoplasm were efficiently presented on the cell surface without any harm effect on cells via MHC class I molecules and result in induction of a large number of effector cell.

• International Journal of Highway Engineering
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• v.11 no.3
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• pp.51-60
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• 2009

This study investigates the fresh state characteristics, strength, chloride ion penetration resistance and freeze-thaw resistance of the suggested high strength-high durability cement concrete pavement. The required workability and air content could be achieved by using an appropriate admixtures. However its dosage should be carefully determined through field trial batches. Compressive strength increased with the increased cement content and, in particular, high cement volume concrete continuously developed strength up to 90 days. No clear relationship, however, existed between flexural strength and cement content. Chloride penetration resistance seemed as a function of curing age rather than the cement content. Freeze-thaw resistance test was conducted using two different coolants, tap water and 4% NaCl solution. When the tap water was used no severe damage was observed up to 300 cycles regardless the air content. Under 4% NaCl solution, specimens of 326kg/$m^3$ cement content showed severe damage with surface scaling. Based on the experimental investigations herein, it is highly recommended that the cement content be greater than 400kg/$m^3$ for strength-high durability cement concrete pavement structures.

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.382-387
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• 2008

$Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ oxide was synthesized by polymerized complex method. Dense membrane of perovskite oxide was prepared using as-prepared powder by pressing and sintering at $1080^{\circ}C$. Leakage test was conducted on the membrane sealed by gold ring, Pyrex ring or Pyrex powder as a sealing material. The oxygen permeation flux of $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ membrane increased with increasing temperature and was $0.74mL/min{\cdot}cm^2$ at $900^{\circ}C$. In the case of the membrane applied by sealing material, oxygen permeation flux of the membrane using gold ring at $950^{\circ}C$ was higher than that using Pyrex materials because the undesired spreading of Pyrex glass materials in the membrane led to the reduction of effective permeation area. Microphotograph analysis results for the membrane after permeation test confirmedthe diffusion of Pyrex glass seal into the membrane.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.111-118
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• 2014

The present study concerns the leachability of alkali ions from hardened cement paste in terms of an increase in the pH together with the rate of alkali leaching. To evaluate the influence of mix design on the leaching capacity and rate of alkali, different water-cement ratios (W/C) and binders were used to manufacture paste specimens. The cement paste was made in the form of rectangular bucket where deionised water was subsequently supplied as solvent media. Then the specimen was wrapped in polythene film to avoid contact to atmospheric conditions, which may affect the water chemistry in the bucket. The pH of media was monitored until no further change in the pH value was observed, of which value then used to calculate the leaching capacity and rate. The influence of binder on the pH of solvent is more dominant than that of water to cement ratio: OPC paste produced the highest level of alkali leaching, whilst 30% PFA and 60% GGBS pastes imposed lower level of alkali leaching. After the monitoring of the pH, the inner bucket was ground with an increment of 1.0 mm to measure the leaching influence using the suspension consisting of paste powder and deionised water. It was found that the impact zone for OPC was about 7-8 mm, whilst 30% PFA and 60% GGBS had deeper impact depth of the alkali leaching.

• Journal of Wetlands Research
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• v.9 no.3
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• pp.35-42
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• 2007

The paved areas such as parking lots and roads are stormwater intensive landuses since they are impervious and have high pollutant mass emissions from vehicular activity. Vehicle emissions include different pollutants such as heavy metals, oil and grease, particulates from sources such as fuels, brake pad wear and tire wear. Especially, the released heavy metals can be easily absorbed on the surface area of small particulate materials because of its ionic strength. Therefore, by constructing the sedimental tank in structural BMPs as a pre-treatment facility, the particles and heavy metals both can be removed from the runoff at an instant. To understand the physico-chemical characteristics of sediments from sedimentation tank, one-year study at an infiltration trench and filtration system was conducted to quantify the metal mass absorbed on sediments with various particle sizes. The structural BMPs for this study are located in Yongin City, Kyunggido. The research results show that Cu, Zn and Pb are dominant metal compounds in the sediments. Also the metal concentrations are highest at the ranges of $425-850{\mu}m$ particle sizes. The results will provide the basic physico-chemical information of sediments to treat it as solid wastes and to determine the design criteria of sedimentation tank in structural BMPs.