• Journal of the Korean Geotechnical Society
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• v.36 no.10
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• pp.33-39
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• 2020

A geological repository has been considered as an option for the disposal of high-level radioactive waste (HLW). The HLW is disposed in a host rock at a depth of 500~1,000 meters below the ground surface based on the concept of engineered barrier system (EBS). The EBS is composed of a disposal canister, buffer material, backfill material, and gap-filling material. The compacted bentonite buffer is very important since it can restrain the release of radionuclide and protect the canister from the inflow of ground water. The saturation of the buffer decreases because high temperature in a disposal canister is released into the surrounding buffer material, but saturation of the buffer increases because of the inflow of ground water. The unsaturated properties of the buffer are critical input parameters for the entire safety assessment of the engineered barrier system. In Korea, Gyeongju bentonite can be considered as a candidate buffer material, but there are few test results of the unsaturated properties considering temperature variation. Therefore, this paper conducted experiment of soil-water characteristic curve for the Gyeongju compacted bentonite considering temperature variation under a constant water content condition. The relative error showed approximately 2% between test results and modified van-Genuchten model values.

• Journal of Practical Engineering Education
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• v.12 no.1
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• pp.163-176
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• 2020

Promoting job growth and quality has been central to developing countries to reduce poverty for decades. In this regard, Nepal is not unique in its need to develop effective TVET programme as it is considered showing positive association with workforce development and productivity. While the copious academic literature has highlighted upon staff training programme in general education, it encounters lack of adequate attention in the field of TVET education. The purpose of the study is to identity and prioritise the professional development needs for the teachers of TVET sector in Nepal. A sample(N=317) of Nepalese teachers from seven provinces were asked to answer the scale. The Borich needs assessment model was employed to assess the perceived level of importance and present preferred training modules among 29 teaching subjects. Moreover, a quadrant analysis using 2×2 matrix was used as a diagnostic tool to denote overriding training topics. The result shows that following competence skills constructs were perceived to be in high need of enhancement as well as in existence of discrepancies: 'occupational characteristics of TVET trainer', 'training needs analysis and curriculum development', 'curriculum development based on national competence standard(NCS)', and 'Institution management evaluation'.

• Toxicological Research
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• v.29 no.1
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• pp.43-52
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• 2013

Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin produced by several species of Fusarium that are found in cereals and agricultural products. ZEN has been implicated in mycotoxicosis in farm animals and in humans. The toxic effects of ZEN are well known, but the ability of an alkaline Comet assay to assess ZEN-induced oxidative DNA damage in Chang liver cells has not been established. The first aim of this study was to evaluate the Comet assay for the determination of cytotoxicity and extent of DNA damage induced by ZEN toxin, and the second aim was to investigate the ability of N-acetylcysteine amide (NACA) to protect cells from ZEN-induced toxicity. In the Comet assay, DNA damage was assessed by quantifying the tail extent moment (TEM; arbitrary unit) and tail length (TL; arbitrary unit), which are used as indicators of DNA strand breaks in SCGE. The cytotoxic effects of ZEN in Chang liver cells were mediated by inhibition of cell proliferation and induction of oxidative DNA damage. Increasing the concentration of ZEN increased the extent of DNA damage. The extent of DNA migration, and percentage of cells with tails were significantly increased in a concentration-dependent manner following treatment with ZEN toxin (p < 0.05). Treatment with a low concentration of ZEN toxin (25 ${\mu}M$) induced a relatively low level of DNA damage, compared to treatment of cells with a high concentration of ZEN toxin (250 ${\mu}M$). Oxidative DNA damage appeared to be a key determinant of ZEN-induced toxicity in Chang liver cells. Significant reductions in cytolethality and oxidative DNA damage were observed when cells were pretreated with NACA prior to exposure to any concentration of ZEN. Our data suggest that ZEN induces DNA damage in Chang liver cells, and that the antioxidant activity of NACA may contribute to the reduction of ZEN-induced DNA damage and cytotoxicity via elimination of oxidative stress.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.766-771
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• 2016

This study examined the long-term durability of PC boxes, which was manufactured by low-carbon eco-friendly concrete using an alternative binder to cement and alternative fine aggregate to sand and microwave heat curing system to reduce the construction cost of a near-surface transit system. Based on the test results, the initial compressive strength of microwave heat cured concrete was higher than that of the steam cured concrete, but those were similar in the long-term age. In addition, there was no significant difference between the two curing conditions in the chemical resistance and the freeze-thawing resistance, and the chloride ion penetration level of the concrete cured by two methods was very low. Therefore, low-carbon eco-friendly concrete and microwave heat curing technology are expected to contribute to the economic construction of a near-surface transit system, and reduce carbon dioxide emissions and environmental impact.

• Analytical Science and Technology
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• v.23 no.2
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• pp.138-146
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• 2010

The Korean Ministry of the Environment revised a few sections of the regulations in the Law of indoor air quality management for the reinforcement or adjustment of the regulation criteria standard for releasing pollutants from building materials. Especially, in case of sealant, the contents covering liquid building materials, excess standards and testing methods have been added simultaneously in this revision, As a result it is impossible to compare original standards with revised standards directly. For this reason, this study reviewed revised test method of sealant pollutant emission rates in terms of impact and validity in comparison with the original test method. Through this study, the basic properties of revised pollutant emission control standards was assessed. Especially in sealant, since each product has a wide deviation of time required for complete drying, it is proved that there are a large number of products that are not hardened completely in test time. The result of our experiments on the revised test methods showed that this revised test methods yield emission rates that are two and half times less than those of the original testing method. To apply the revised test method of sealant to all the sealant products, It is necessary to extend the test period or improve specimen to fit the test method for quickly drying sealant products.

• Food Science of Animal Resources
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• v.25 no.1
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• pp.13-19
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• 2005

The radio-sensitivity of pathogens and the effect of irradiation on microbiologican safety and mutagenicity of meat products such as seasoned and cooked beef and ham were investigated. Samples were radiation-sterilized and inoculated at 10/sup 7/ cfu/g with each of the four pathogens including Salmonella typhimurium, Escherichia coli, Staphylcoccus aureus, and Listeria ivanovii. No viable cells of pathogens were observed in the sample irradiated with 3 kGy. The D/sub 10/ value of inoculated pathogens in seasoned and cooked beef and ham were 0.24∼0.48 and 0.39∼0.45, respectively. Results of Ames test performed with non-irradiated and irradiated seasoned and cooked beef and ham were both negative at the level of 625, 1,250, 2,500, 50,000, and! 10,000 ㎍ sample/plate, respectively. Results indicate that low dose (2∼3 kGy) irradiation is effective to ensure safety for seasoned and cooked beef and ham with toxicological wholesomeness.

• Journal of the East Asian Society of Dietary Life
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• v.19 no.4
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• pp.525-532
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• 2009

The purpose of this study was to compare the ability of Northeast Asians to discriminate the salinity in salt solution and foods, and to compare their preference of salinity. Panels of Korean, Japanese and Chinese evaluated three kinds of samples that contained different level of salt such as salt solutions, julienned radish salad, Bulgogi. The salt levels had been manipulated to produce five samples of each one. The salt solutions were prepared by adding 0.3%, 0.7%, 1.1%, 1.5%, 1.9% salt into water. Different levels of salt in Julienned radish salad and Bulgogi were prepared by adding 0.5%, 1.5%, 2.5%, 3.5%, 4.5% salt to the recipe. The results of this study showed that the three ethnic groups had significant differences in their ability to distinguish the intensity of salinity in solutions containing a high contents of salt(1.5~1.9%). According to the regression analysis, Koreans(a=1.050) turned out to be the most able to detect the intensity of salinity, compared to the Japanese (a=0.988) and Chinese (a=0.807). All ethnic groups preferred a salt concentration of 0.3%, and the preference for this concentration was lower in Japanese than in Koreans and Chinese. There were significant differences in the perception of salinity in the julienned radish salad containing more than 3.5% salt between Koreans and Chinese. Koreans (a=1.168) appeared to be the most able to detect the intensity of salinity, compared to the Japanese (a=0.908) and Chinese (a=0.793). Both Koreans and Japanese had the strongest preference for the julienned radish salad containing a 1.5% salt concentration, while the Chinese preferred a salt concentraion of 2.5%. The ability of ethnic groups to detect the salinity in Bulgogi were significantly different at high salt -concentrations (more than 3.5%), and the awareness of salinity was as fallows : Koreans(a=0.161) > Japanese (a=0.896) > Chinese (a= 0.845). Koreans and Japanese had a higher preference or the Bulgogi containing a salt concentration of 1.5%, and the Chinese had higher preference at a salt concentration of 2.5%.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.20-29
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• 2014

Recently, LTE is preparing to make a new leap forward LTE-A all over the world. As LTE privides high speed service, the role of mobile phones seems to change from voice to data service. According to Cisco, global mobile data traffic will increase nearly 11-fold between 2013 and 2018. Mobile video traffic will reach 75% by 2018 from 66% in 2013 in Korea. However, voice service is still the most important role of mobile phones. Thus, controllability of throughput and low BLER is indispensable for high-quality VoIP service among various type of traffic. Although the maximum AMR-WB, 23.85 Kbps is sufficient to a VoIP call, it is difficult for the LTE which can provide tens to hundreds of MB/s may not keep the certain level VoIP QoS especially in the cell-edge area. This paper proposes a new scheduling algorithm in order to improve VoIP performance after analyzing various scheduling algorithms. The proposal is the technology which applies more priority processing for VoIP than other applications in cell-edge area based on two-tier scheduling algorithm. The simulation result shows the improvement of VoIP performance in the view point of throughput and BLER.

• Journal of the Korean Society for Railway
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• v.17 no.4
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• pp.251-259
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• 2014

The transition zone between an earthwork and a bridge effect to the vehicle's running stability because support stiffness of the roadbed is suddenly changed. The design criteria for the transition structure on ballast track were not particular in the past. However with the introduction of concrete track is introduced, it requires there is a higher performance level required because of maintenance and running stability. In this present paper, a transition structure reinforced with geosynthetics is suggested to improve the performance of existing bridge-earthwork transition structures. The suggested transition structure, in which there is reinforcing of the approach block using high-tension geosynthetics, has a structure similar to that of earth reinforced abutments. The utilized backfill materials are cement treated soil and gravel. These materials are used to reduce water intrusion into the approach block and to increase the recycling of surplus earth materials. An experiment was performed under the same conditions in order to allow a comparison of this new structure with the existing transition structure. Evaluation items are elastic displacement, cumulative settlement, and earth pressure. As for the results of the real-scale accelerated testing, the suggested transition structure has excellent performance for the reduction of earth pressure and settlement. Above all, it has high resistance the variation of the water content.

• Particle and aerosol research
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• v.16 no.2
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• pp.49-59
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• 2020

Various devices have been developed to the measurement of particulate matter pollutants, and Optical Particle Counter (OPC) that can be easily and quickly measured is widely used lately. The measured value by OPC is converted to weight concentration using the correction factor (CF). The calculation of CF is very important to improve the reliability and accuracy of OPC. In this study, the CF calculation study of light scattering laser photometer (model 8533, TSI) was carried out to measure in the atmospheric environment using 2 gravimetric devices and 3 light scattering laser photometer devices. Regression analysis and Tukey tests were used to significance the test of measurement devices. Measurements were carried out twice. There was a comparative analysis of measurement data between light scattering laser photometer and gravimetric devices in 1st measurement, and then the Evaluation of PM2.5 concentration corrected by CF performed in 2nd measurement. As a result of the significance analysis between light scattering laser photometer and gravimetric devices, the correlation between the same method was high, but the correlation between different methods was low. CF was calculated as 0.4258 based on the measurement results, and it is a similar level to previous studies at home and abroad. It is expected that these results can be used as basic data in the future study for air quality measurement research using light scattering laser photometer. Also, in order to improve the accuracy of the measurement techniques and the development of technology in the atmospheric environment, CF calculation research should be conducted continuously.