• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.925-928
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• 2008

Fiber is an important ingredient in strain-hardening cementitious composite (SHCC), which can control fracture of cementitious composite by bridging action. The properties of reinforcing fiber, as tensile strength, aspect ratio and elastic modulus, have great effect on the fracture behavior of SHCC. To apply SHCC to structural member, SHCC must have economical efficiency and workability as well as own excellent tensile performance. For these purposes, four-point bending and direct tensile tests on SHCC with only hybrid synthetic fibers, total fiber volume fraction, $V_f$, is 1.5%, are carried out. The research emphasis is on the mechanical properties of SHCC made in Polyvinyl alcohol (PVA) and Polyethylene (PE) fibers, and how this affects the composite property, and ultimately its strain-hardening performance. Also, effect of hybrid type and water-cement ratio on the behavior of SHCC was evaluated in this paper.

• Journal of Ecology and Environment
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• v.29 no.5
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• pp.479-484
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• 2006

Ecophysiological parameters of non-transgenic sweetpotato (NT) and transgenic sweetpotato (SSA) plants were compared to evaluate their resistance to multiple environmental stresses. Stomatal conductance and transpiration rate in NT plants decreased markedly from Day 6 after water was withheld, whereas those values in SSA plants showed relatively higher level during this period. Osmotic potential in SSA plants was reduced more negatively as leaf water potential decreased from Day 8 after dehydration treatment, while such reduction was not shown in NT plants under water stressed condition. SSA plants showed less membrane damage than in NT plants. As water stress and high light stress, were synchronously applied to NT and SSA plants maximal photochemical efficiency of PS II ($F_v/F_m$) in NT plants markedly decreased, while that in SSA plants was maintained relatively higher level. This trend of changes in $F_v/F_m$ between SSA plants and NT plants was more conspicuous as simultaneously treated with water stress, high light and high temperature stress. These results indicate that SSA plants are more resistive than NT plants to multiple environmental stresses and the enhanced resistive characteristics in SSA plants are based on osmotic adjustment under water stress condition and tolerance of membrane.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.177-180
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• 2008

SHCC shows the high energy tolerance capacity due to the interfacial bonding of the fibers to the cement matrix. For effective material design and application of SHCC, it is needed to investigate the damage process and micro-fracture mechanism of cement matrix reinforced with different types of fibers. The objective of this paper is to investigate the direct tensile response of cement composites reinforced with single and hybrid fibers using acoustic emission(AE) technique. In this study, the correlations between AE signal and result of the direct tensile response of SHCC. For these purposes, three kinds of fibers were used: PET1.5%, PET1.0+PE0.5%, PET1.0%+PVA0.5%. The result of the direct tensile response of SHCC, for the same volume fraction of fibers, ultimate strength of PET-PE specimen was 2.7 times higher than specimens with PET fibers. And from AE signal value, AE event numbers and cumulative energy were different according to kind of fiber because of the different material properties of reinforced fiber.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.431-439
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• 2015

The methods which decrease the accident hazards of LPG(Liquefied Petroleum Gas) terminal on the basis of butane & propane storage tanks by applying HAZOP(Hazard and Operability), LOPA(Layer of Protection Analysis) and SIL(Safety Integrity Level) are suggested. The accident scenarios were derived by analyzing latent risks through the HAZOP. The scenarios which would have the big damage effect in accidents were selected and then LOPA was assessed by analyzing IPL(Independent Protection Layer) about the correspond accident scenarios. The improved methods were proposed on the basis of level of SIF(Safety Instrumented Functions) as a IPL considering satisfied condition of risk tolerance criteria($1.0{\times}10^{-05}/y$). In addition, The proposed IPLs were basis on the economic analysis. The effect of SIF as a IPL considering the changes of accident frequency was studied in case of the accident scenarios derived from the concerned process.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.566-574
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• 2016

Fiber metal laminates, which are hybrid materials consisting of metal sheets and composite layers, have contributed to aerospace and automotive industries due to their reduced weight and improved damage tolerance characteristics. In this study, the impact performance of the laminates, which are comprised of a self-reinforced polypropylene and two aluminum sheets, and the pure aluminum alloy sheet material were investigated experimentally via numerical simulation. In order to compare the impact performance, the laminates and aluminum alloy were examined by assessing the impact force, energy time histories, and specific energy absorption. ABAQUS is a commercial software that is used to simulate the actual drop-weight tests. Based on this study, it is noted that the impact performance of the laminates was superior to that of the aluminum alloy. In addition, a good agreement between the experimental and numerical results can be achieved when the impact force and energy time histories from the experiments and the numerical simulations are compared.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.244-250
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• 2015

Survivability is avoidance and tolerance ability of combat systems for accomplishing mission in battle field. Therefore, the combat system has to protect or minimize any damage from threats. For this reason, many modeling and simulation based studies which analyze vulnerability of the combat system by threats, are in progress to improve survivability of the combat system. In this paper, we developed a 3D penetration analysis program for survivability analysis of combat system. To do this, we applied the penetration analysis equation to threat and protection performance of tank. Also we implemented simple tank models based on 3D CAD, and tested the developed program using the implemented tank models. As a result, we verified the developed program that is possible to analyze penetration by threat and protection performance of tank and to visualize its result, based on scenarios.

• Laboraroty Animal Research
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• v.34 no.4
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• pp.185-194
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• 2018

The different polymorphisms of the transcription factor 7-like 2 (TCF7L2) gene promote variances in diabetes susceptibility in humans. We investigated whether these genotypes also promote differences in diabetic susceptibility in commercial pigs. Growing pigs (Landrace, both sex, 50-60 kg) with the C/C (n=4) and T/T (n=5) TCF7L2 genotypes were identified and intravenously injected with streptozotocin (STZ, 40 mg/kg) twice in weekly intervals, then a high-energy diet was offered. Oral glucose tolerance tests, blood analyses and the homeostasis model assessment-insulin resistance (HOMA-IR) index calculations were performed. The animals were sacrificed at the end of 12 weeks of treatment to reveal the pancreas histomorphometry. The results showed that all of the treated pigs grew normally despite exhibiting hyperglycemia at two weeks after the induction. The glycemic level of the fasting or postprandial pigs gradually returned to normal. The fasting insulin concentration was significantly decreased for the T/T carriers but not for the C/C carriers, and the resulting HOMA-IR index was significantly increased for the C/C genotype, indicating that the models of insulin dependence and resistance were respectively developed by T/T and C/C carriers. The histopathological results illustrated a significant reduction in the pancreas mass and insulin active sites, which suggested increased damage. The results obtained here could not be compared with previous studies because the TCF7L2 background has not been reported. Growing pigs may be an excellent model for diabetic in children if the animals are genetically pre-selected.

• Journal of odor and indoor environment
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• v.17 no.4
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• pp.337-345
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• 2018

In this study, we measured the concentration of Particulate Matter($PM_{10}$), Formaldehyde(HCHO), and Total Bacteria Count (TBC) at two facilities: day care centers, and postnatal care centers located in the cities of Gyeonggi, Gangwon, Jeolla and Gyeongsang from January 1, 2012 to December 31, 2015. $PM_{10}$ concentration was similar to the day care centers and postnatal care centers. HCHO concentration was the highest in the postnatal care centers. TBC concentration was the highest in the day care centers. Comparing the different cities, $PM_{10}$ concentration was the highest in Gyeonggi, HCHO concentration was the highest in Gyeonggi, and TBC concentration was the highest in Gyeonggi. As a result of HCHO's risk assessment, it was found that adults exceeded the carcinogenicity tolerance of $10^{-6}$ specified by the US EPA. This study is expected to be helpful in preventing damage to health from the contaminated indoor air at sensitive facilities, and can be used as basic data for indoor air quality management.

• Journal of Ginseng Research
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• v.43 no.4
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• pp.517-526
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• 2019

Background: The root of Panax ginseng, a member of Araliaceae family, has been used as herbal medicine and functional food in Asia for thousands of years. According to Traditional Chinese medicine, ginseng is the most widely used "Qi-invigorating" herbs, which provides tonic and preventive effects by resisting oxidative stress, influencing energy metabolism, and improving mitochondrial function. Very few reports have systematically measured cell mitochondrial bioenergetics after ginseng treatment. Methods: Here, H9C2 cell line, a rat cardiomyoblast, was treated with ginseng extracts having extracted using solvents of different polarity, i.e., water, 50% ethanol, and 90% ethanol, and subsequently, the oxygen consumption rate in healthy and tert-butyl hydroperoxideetreated live cultures was determined by Seahorse extracellular flux analyzer. Results: The 90% ethanol extracts of ginseng possessed the strongest antioxidative and tonic activities to mitochondrial respiration and therefore provided the best protective effects to H9C2 cardiomyocytes. By increasing the spare respiratory capacity of stressed H9C2 cells up to three-folds of that of healthy cells, the 90% ethanol extracts of ginseng greatly improved the tolerance of myocardial cells to oxidative damage. Conclusion: These results demonstrated that the low polarity extracts of ginseng could be the best extract, as compared with others, in regulating the oxygen consumption rate of cultured cardiomyocytes during mitochondrial respiration.

• Journal of Environmental Science International
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• v.30 no.3
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• pp.235-243
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• 2021

This study was conducted to investigate the growth of Dendranthema zawadskii in damaged soils when they are treated with improvement agents. The treatments consisted of a control (unamended field soil) and the application of a loess ball of 1 cm to the field soil. According to the degree of damage the de-icing agent had caused, the soils were divided into 3 areas (based on the yellowing of Pinus densiflora for. multicaulis in soil surveys): H (high saline), M (medium saline), and L (low saline). A total of six treatments were performed: D. zawadskiia plant without soil amendment (H; high saline soil, M; medium saline soil, L; low saline soil), and a D. zawadskiia plant with loess ball on the soil surface (H.L; high saline soil with loess ball, M.L; medium saline soil with loess ball, L.L; low saline soil with loess ball). The results showed that D. zawadskiia growth went from highest to lowest in the order: M.L > L.L > M > L > H.L > H. Plant growth results showed that soils treated with soil amendments (loess ball) were better for D. zawadskii growth than untreated soils.