• Journal of the Korean Society for Heat Treatment
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• v.33 no.6
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• pp.290-295
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• 2020

In this study, Electro spinning was carried out using Cabon nanotube 0.1%-Polyacrylonitrile 3%-Dimethylformamide 17% agitation solution. It was investigated the solute and solvent correlations according to the electro spinning voltages ranging form 5 to 40 kV, based on the SEM image. Except voltage 25 kV, electro spinning was failed due to the lack of electro spinning (less than 60%). Voltage 25 kV was showed excellent properties, and was confirmed Cabon nanotube 58.1 nm and diameter of Cabon nanotube + Polyacrylonitrile 1.76 ㎛ as shown SEM image. Also, the tensile test results were showed that SK Chemical prepreg electro spinning angle of 0 and 90 degrees were 137 MPa and 60 MPa, respectively.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.110-117
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• 1997

Alloy 690 제1열 시제 전열관을 U 굽힘 가공할 시 전열관에 도입된 표면 잔류응력 및 굽힘 단면에서 치수변화 (벽두께, 진원도)를 위치별로 측정하여 평가하였다. 외측호(extrados)의 표면 잔류응력은 $\psi$=0$^{\circ}$에서 축 방향 응력이 -319 MPa (압축)로 가장 높았으며, 내측호(intrados)는 $\psi$=0$^{\circ}$, 160$^{\circ}$ 위치인 천이영역 부관에서 응력 변화가 크게 되는 경향을 보였다 측면(flank)은 인장 잔류응력으로 $\psi$=90$^{\circ}$(apex)에서 최대 190 MPa 로 축방향 응력으로 나타났다. 잔류응력치는 벽두께 보다는 진원도 변화와 일치되어 나타났으며, 시제 전열관의 벽두께 및 진원도는 ASTM의 치수 허용치 내에 포함되는 것으로 평가되었다. 잔류응력 측정은 스트레인 게이지를 이용한 구멍뚫기 방법 (Hole-Drilling Method)을 사용하였다.

• Korean Journal of Metals and Materials
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• v.49 no.8
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• pp.642-648
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• 2011

This paper describes an experimental study on ultrasonic welding of similar and dissimilar metals. There are optimum welding conditions which are found for welding of Al/Al and Al/Cu. It evaluated weldability using tensile test, SEM observation and EDX-ray analysis. Both ultrasonic welding of Al/Al and Al/Cu have amplitude as the variable factor. Al/Cu welding was examined again with welding time as variable factor to find the best conditions. The more welding time or amplitude increase, the better weldability. The optimum conditions for ultrasonic welding of Al/Al were formed at pressure 0.25 MPa, welding time 0.25 sec, amplitude 90%. Pressure 0.25 MPa, welding time 0.4 sec, amplitude 80% are optimized for Al/Cu ultrasonic metal welding and solid-state diffusion generated by ultrasonic vibration and frictional heat is confirmed at the welded interface.

• Computers and Concrete
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• v.26 no.6
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• pp.577-585
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• 2020

By the increasing amount of waste materials, it eventually dumped into the environment and covering a larger area of the landfill which cause several environmental pollution problems. The utilization of Palm Kernal Shell Ash (PKSA) in concrete might bring a great benefit in addressing both environmental and economic issues. This article investigates the effect of PKSA as a partial cement replacement of High Strength Concrete (HSC). Several concrete mixtures were prepared with different PKSA of 0%, 10%, 20%, and 30% replaced by the cement mass. This procedure was replicated twice for the two different target mean strengths of 40 MPa and 50 MPa. The mixtures were prepared to test different fresh and hardened properties of HSC including slump test, the compressive strength of 3, 7, 14, 28, and 90 days, flexural strength of 28-days, drying shrinkage, density measurement, and sorptivity. It was observed 10% PKSA replacement as optimum percentage which reduced the drying shrinkage, sorptivity, and density and improved the late-age compressive strength of concrete.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.1057-1061
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• 2002

Effects of modifier and soaking on extraction of triterpenoid saponin (glycyrrhizin) from liquorice were examined using supercritical $CO_2(SC-CO_2)$ at 50 MPa, $60^{\circ}C$, and flow rate of 3 mL/min, and glycyrrhizin content was analyzed by HPLC. Additon of undiluted methanol, ethanol or isopropanol as modifier to $SC-CO_2$ had little influence on extraction yield of glycyrrhizin. Soaking process using water increased the extraction yield as the sample to solvent ratio was increased. Addition of 70% methanol, ethanol or isopropanol to $SC-CO_2$ significantly increased the extraction yields, with 70% methanol resulting in the highest yield. When water at 90% (w/w) of sample weight was used for soaking, the extraction yield and rate increased, 70% ethanol-modified $SC-CO_2$ was almost equal to that obtained using 70% methanol.

• Food Science of Animal Resources
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• v.42 no.1
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• pp.142-152
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• 2022

The present study was aimed at examining the antibacterial effects of nonthermal decontamination processes, which are equivalent to thermal treatment, to ensure microbiological safety of raw ground chicken. Escherichia coli or Salmonella were inoculated into 25 g of raw ground chicken samples. The raw ground chicken samples were non-treated or treated with high hydrostatic pressure (HHP) at 500 MPa (1-7 min), light-emitting diode (LED) irradiation at 405 nm wavelength (30-120 min), and heat at 70℃, 90℃ (1-60 min), and 121℃ (1-15 min). E. coli and Salmonella cell counts were enumerated after treatments. Moreover, the color parameters of treated raw ground chicken were analyzed. HHP treatment reduced E. coli and Salmonella cell counts by more than 5 Log CFU/g and more than 6 Log CFU/g after 7 min and 1 min, respectively; these effects were equivalent to those of thermal treatment. However, LED irradiation reduced Salmonella cell counts by only 0.9 Log CFU/g after 90 min of treatment, and it did not reduce E. coli cell counts for 90 min. Compared with those of the non-treated samples, the ΔE (total color difference) values of the samples treated with HHP were high, whereas the ΔE values of the samples treated with LED irradiation were low (1.93-2.98). These results indicate that despite color change by HHP treatment, HHP treatment at 500 MPa could be used as a non-thermal decontamination process equivalent to thermal treatment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.4
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• pp.577-586
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• 2013

This study investigated black garlic and mugwort extracts have anti-stress activity. The antioxidant activities of extracts from black garlic (BEP), mugwort (MEP), and three mixtures (MPA, 95:5; MPB, 90:10; MPC, 85:15, w/w% for BEP and MEP, respectively) were tested in vitro. DPPH and ABTS radical scavenging activities for the mixtures (MPA, MPB and MPC) were significantly elevated in a dose-dependent manner by the amount of mugwort extract. A restraint stress was imposed on six groups of Sprague-Dawley rats supplemented with an AIN-93 diet (RSC) or one of five kinds of hot water extract drinks containing (black garlic, RS1; mugwort, RS2; and mixtures of black garlic : mugwort at 95:5, RS3; 90:10, RS4, and a mixture of black garlic : mugwort : apple extract : xylitol=90.25:4.75:2:3, RS5; v/v%) for 4 weeks. The normal group was fed with the AIN-93 diet and not exposed to restraint stress. Food intake was higher in the group fed with garlic extract (RS1), while the body weight gain and food efficiency ratio did not significantly change. The total serum cholesterol content in the RS1 and RS2 groups was significantly lower than the RSC group (control), and the RS5 group was not significantly different compared to the RS3 group. The serum triglyceride content was significantly higher RS3~RS5 groups than RS1 and RS2 groups. In terms of HDL-C and LDL-C contents, AI and CRF in the serum were not significantly different between RS3 and RS5 groups. AST and ALP activities of RS1~RS5 groups were significantly lower than the RSC group. The liver total lipid and cholesterol contents of RS1~RS5 groups were significantly lower than RSC group, and triglyceride content was significantly lower in the RS1 group. Glycogen in the liver tissue was significantly higher in the RS2 and RS3 group compared to the RSC group. These results show that the intake of a mixture of black garlic and mugwort extracts may be effective in the alleviation of hyperlipidemia caused by restraint stress.

• Journal of the Korean Wood Science and Technology
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• v.42 no.3
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• pp.290-300
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• 2014

In this study, cross-laminated woods were made with spruce wood and the effects of annual ring angles of perpendicular direction laminae on static bending strength performance were investigated. Static bending strength performances of parallel laminated woods with all layers composed of laminae perpendicular to the grain ($P_{\bot}$ type) were in the order of $90^{\circ}$ > $0^{\circ}$ > $45^{\circ}$. The MOE and MOR for the $45^{\circ}$ annual ring angle were 0.0989 GPa and 3.25 MPa, and it showed the lowest values. By placing longitudinal-direction laminae in the core of $P_{\bot}$ type, the strength performances were markedly improved. In the case of cross-laminated woods with perpendicular-direction laminae in the faces ($C_{\bot}$ type), the bending strength performances were in the order of $90^{\circ}$ > $0^{\circ}$ > $45^{\circ}$, but the differences among annual ring angles were less than those of the parallel-laminated woods. In the case of cross-laminated woods with perpendicular-direction laminae in the core ($C_{\parallel}$ type), the bending strength performances were in the order of $45^{\circ}$ > $90^{\circ}$ > $0^{\circ}$ unlike $P_{\bot}$ type and $C_{\bot}$ type. The MOE and MOR for the $45^{\circ}$ annual ring angle were 12.0 GPa and 55.8 MPa, and it showed the highest values.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.2 s.173
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• pp.279-289
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• 2000

Residual stress induced in U-bending and tube-to-tubesheet joint processes of PWR's row-1 heat exchanger tube was measured by X-ray method and Hole-Drilling Method(HDM). Compressive residual stresses(-) at the extrados surface were induced in U-bending, and its maximum value reached -319 MPa in axial direction at the position of $\psi$ = $0^{\circ}$. Tensile residual stresses(+) of $\sigma_{zz}$ = 45 MPa and $\sigma_{\theta\theta}$ = 25 MPa were introduced in the intrados surface at the position of $\psi$ = $0^{\circ}$. Maximum tensile residual stress of 170 MPa was measured at the flank side at the position of $\psi$ = $90^{\circ}$, i.e., at apex region. It was observed that higher stress gradient was generated at the irregular transition regions (ITR). The trend of residual stress induced by U bending process of the tubes was found to be related with the change of ovality. The residual stress induced by the explosive joint method was found to be lower than that by the mechanical roll method. The gradient of residual stress along the expanded tube was highest at the transition region (TR), and the residual stress in circumferential direction was found to be higher than the residual stress in axial direction.

• Journal of the Korean Geotechnical Society
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• v.27 no.2
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• pp.81-90
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• 2011

Domestic usage of high strength steel for pile has been limited to steel with yield strength (YS) of 490 MPa. However, design and construction cases abroad show beneficial usage of steel pipe with YS ranging in 500~700 MPa. In this study, YS 590 MPa steel pipe has been tested for driven pile foundation in Songdo area. Pile dynamic analysis (PDA) was carried out for 18 piles of which 16 piles have been reviewed for comparison of the PDA test results with those of GRLWeap analysis using SPT N value. Back analysis of PDA analysis was also carried out to narrow the deviation of standard SPT N value used in GRLWeap analysis. A regression equation is suggested for the shaft and toe resistance according to SPT N values for future GRLWeap analysis that can be used in the designing stage at Songdo area.