• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.46-53
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• 2003

For the tensile tests of the F.E.M., microvoids are created by the boundary separation process at the martensite boundary or neighborhood and at inclusions within the fracture. to grow to the ductile dimple fracture. For the case of the M.E.F., microvoids created at the discontinuities of the martensite phase which exists at the grain boundary of the primary ferrite are grown to coalescence with the cleavage cracks induced at the interior of the ferrite, which as a result show the discontinuous brittle fracture behavior. In spite of their similar tensile strengths, the fatigue limit and the notch sensitivity of the M. E.F. is superior to those of the F.E.M., The M.E.F. is much more insensitive to notch than F.E.M. from the stress concentration factor($\alpha$).

• Tunnel and Underground Space
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• v.20 no.4
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• pp.299-307
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• 2010

The model experiments, which employ a charge hole and guide hole, are simulated to examine the effect of the guide hole on the crack propagation control in blasting. Crack patterns resulted from the analysis models, which consider the distance between the charge hole and guide hole, were compared. From the simulation analysis for the model experiments, it was revealed that all the guide holes used in this study were effective for controlling the crack propagation in blasting.

• Food Science and Preservation
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• v.15 no.1
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• pp.105-110
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• 2008

The antioxidant properties of bamboos sap isolated from Phyllostachys pubescens were investigated. This product scavenged intracellular reactive oxygen species (ROS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and prevented lipid peroxidation. The radical scavenging activity of bamboo sap protected the viability of peritoneal macrophage cells exposed to hydrogen peroxide $(H_2O_2)$, Furthermore, bamboo sap reduced apoptotic cell formation induced by $H_2O_2$ as demonstrated by decreases in the number of hypo-diploid cells am apoptotic cell body formation. These results indicate that bamboo sap has radical scavenging activity and ameliorates $H_2O_2$ induced cytotoxicity.

• Elastomers and Composites
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• v.41 no.3
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• pp.172-181
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• 2006

Flame retardant synergism of phyllite was studied in ABS resins containing brominated flame retardant(tetrabromobisphenol A(TBBA) or brominated epoxy oligomer(BEO)) and antimony trioxide($Sb_2O_3)$. Talc was used for the comparison purpose. ABS compounds were manufactured by a twin-screw co-rotating extruder and subsequently injection molded into several specimen for mechanical and thermal properties. Flame retardancy of ABS compounds measured by UL 94 vertical test with 1.6 mm thick bar specimen was enhanced by the replacement of antimony trioxide into phyllite or talc in the range of 12.5%(0.5 wt%) to 37.5%(1.5 wt%). Phyllite showed better synergistic effect comparing with talc especially for BEO. Only phyllite enhanced the flowability of ABS compounds. Notched Izod impact strength decreased with the proportion of phyllite or talc content. Phyllite could replace the antimony trioxide up to the content of 25%(1 wt%) to give better flame retardancy and flowability without darkening problem.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.47-54
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• 2023

In this study, the tensile behavior of concrete specimens reinforced with GFRP (Glass Fiber Reinforced Polymer), BFRP (Basalt Fiber Reinforced Polymer), and CFRP (Carbon Fiber Reinforced Polymer) bars was experimentally analyzed. The tensile strength of the FRP bars is appeared to be similar to the design strength, but the elastic modulus was somewhat lower. Additionally, the specimens for tension stiffening effect were manufacured using OPC (Ordinary Portland Cement) and SFRC (Steel Fiber Reinforced Concrete), with dimensions of 150(W)×150(B)×1000(H) mm. The crack spacing of specimens was most significant for GFRP reinforcement bars, which have a lower elastic modulus and a smoother surface, while BFRP and CFRP bars, with somewhat rougher surfaces and higher elastic moduli, showed similar crack spacings. In the load-strain relationship, GFRP bars exhibited a relatively abrupt behavior after cracking, whereas BFRP and CFRP bars showed a more stable behavior after the cracking phase, maintaining a certain level of tension stiffening effect. The tension stiffening index was somewhat smaller as the diameter increased, and GFRP, compared to BFRP, showed a higher tension stiffening index.

• Explosives and Blasting
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• v.34 no.3
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• pp.1-9
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• 2016

The shaped charge were made for identifying the effect of controled blasting using relatively low VOD explosive for cutting rock mass with changing quality and thickness of metal liner. The metal liner was attached on both sides of a charge for directional cutting, when the shaped charge exploded in rock mass. Also, a efficiency of shaped charge was identified by concrete member experiment. And a center guide used for maintaining stand-off between shaped charge and hole wall. A case of Fe liner of thickness 0.8mm formed the deepest notch of experiments and the directional cutting of concrete member was identified.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.3
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• pp.311-316
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• 2005

Fermentation properties and in vitro anticancer effect of young radish (YR) kimchi and young radish watery (YRW) kimchi were investigated during fermentation at 5℃. The fermentation of YR kimchi during 2-3 weeks led to the decrease of pH down to pH 4.3, increased acidity, and the highest Leuconostoc sp. counts. YR kimchi showed the acidity of 1.04-1.27% at the pH 4.3, when the kimchi was ripened properly. The fermentation of YRW kimchi during 9 days led to the decrease of pH down to pH 4.3 and the acidity of 0.20%. Inhibitory effects of the juices of YR, YR kimchi, and YRW kimchi on the growth of AGS human gastric adenocarcinoma cells in MTT assay were increased with the added concentration. The juice of YR kimchi had a higher inhibitory effect on the growth of AGS human gastric adenocarcinoma cells than that of YRW kimchi at same concentration. The juice of YR kimchi showed similar inhibitory effects on the growth of AGS human gastric and HT-29 human colon adenocarcinoma cells in MTT assay to baechu kimchi, which the inhibition rates are more than 50%.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.5
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• pp.429-438
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• 2003

The effects of fiber orientation on acoustic emission(AE) characteristics have been studied for the unidirectional and satin-weave, continuous glass-fiber reinforced plastic(UD-GFRP and SW-GFRP) tensile specimens. Reflection and transmission optical microscopy was used for investigation of the damage zone of specimens. AE signals were classified as different types by using short time fourier transform(STFT) : AE signals with high intensity and high frequency band were due to fiber fracture, while weak AE signals with low frequency band were due to matrix and interfacial cracking. The feature in the rate of hit-events having high amplitudes showed a process of fiber breakages, which expressed the characteristic fracture processes of individual fiber-reinforced plastics with different fiber orientations and with different notching directions. As a consequence, the fracture behavior of the continuous GFRP could be monitored as nondestructive evaluation(NDE) through the AE technique.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.5
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• pp.747-756
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• 2016

In this paper, a connection details for precast arch structures was proposed. Experiments were performed to evaluate structural performance of the loop connection details satisfying current design requirements and of alternative details for improvement of constructability. Precast arch specimens considering the current design requirements showed higher structural capacity than a cast-in-place arch specimen. Crack width at the connection of arch crown showed smaller value than 0.2 mm due to increased compression force by the applied vertical load. Strengthening by wire-mesh at notch area of the connection improved initial crack control capability. Connection detail with couplers and headed bars showed similar capacity to the reference specimen. The alternative details to improve constructability of reinforcements can be used without decreasing structural performance. Specimens with smaller internal diameter of mandrel and shorter loop splicing than the current design codes showed worse behavior in terms of crack width control.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.10
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• pp.1520-1524
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• 2005

Young radishes (YR, yeolmu in Korean) were cultivated in the soil with and without sulfur. Young radish kimchi-general (YR kimchi-G) was prepared with YR commonly cultivated in the soil without sulfur. Young radish kimchl-sulfur (YR kimchi-S) and young radish kimchi-sulfur with lime mortar (YR kimchi-SL) were prepared with the YR cultivated in the soil with sulfur an4 sulfur added lime mortar on it respectively. Antitumor effects of methanol extracts from the YR kimchis were investigated in sarcoma-180 tumor cell transplanted mice. The solid tumor growth was significantly inhibited by the YR kimchi-SL prepared with YR grown in the soil with sulfur (p < 0.05). The treatment of the methanol extracts from YR kimchi-S and -SL increased the glutathione S-transferase activities and glutathione contents in the livers, compared to thlose of YR kimchi-G and the control. One of the antitumor effects by the YR kimchis was due to the increased the glutathione levels and the glutathione S-transferase activity which is phase 2 enzyme. These results also suggested that the antitumor effects of YR kimchi can be enhanced by using YR cultivated differently in the presence of sulfur that can help to produce sulfur-containing compounds in YR.