• Composites Research
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• v.30 no.3
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• pp.188-192
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• 2017

The mechanical properties of composites are significantly affected by external environment. It is essential to understand the degradation of material performance and judge the material's lifetime in advance. In the current research, changes in mechanical properties of glass fiber and unsaturated polyester composite materials (GFRP, Glass fiber reinforced plastic) were investigated under different bending stress and submerged in hot water at a temperature of $80^{\circ}C$. Loading time of 100 H (hours), 200 H, 400 H, 600 H, 800 H for testing under stresses equal to 0% (stress-free state), 30%, 50% and 70% of the ultimate strength was applied on the GFRP specimens. From the values of bending stress, obtained from three-point bending test, fracture energy, failure time, and life curve were analysed. Moreover, a normalized strength degradation model for this condition was also developed. It was observed that within 100 H, the decline rate of the bending strength was proportional to the pressure.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.11
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• pp.1543-1545
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• 2002

A T$\longrightarrow$A mutation in the promoter region of porcine myostatin (MSTN) gene has been identified in our previous work. This study analyzed the associations of the myostatin genotypes (TT, TA) caused by this mutation with birth weigh in Yorkshire pigs. Data from 211 unrelated individuals were collected three times from one breeding farm. Detections of the mutation were carried out by PCR-RFLPs approach. The effects of MSTN genotypes (TT and TA) on birth weight were compared by least square means. The results showed that for birth weight of Yorkshire pigs, individuals with TA genotype were significantly higher than those with TT genotype (p<0.05), and the birth weight for pigs with TA genotype were 1.37 kg in average but only 1.25 kg for pigs with TT genotype, indicating a positive effect of birth weight for A allele.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1273-1278
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• 2007

The cement-asphalt mortar is a mixture of cement and asphalt emulsion, and is utilized as a underpouring materials for the railway track which is used to fill under slab panel space so as to provide a stabilized track support and a tool for reduction of noise and vibration. To increase the workability of grouting, this study investigates the effect of temperature on cement-asphalt mortar by analyzing its physical and mechanical properties before/after hardening according to the temperature (10, 15, 20, 25, $30^{\circ}C$). According to the test results, it is found that as for the physical property of fresh cement-asphalt mortar the more mixture temperature become higher or lower, the more fluidity become worse. But by increasing reducing agent amount and its unit quantity, the required fluidity is met. The compressive strength as physical property of hardened cement-asphalt mortar become lower when temperature is lower but taking it by and large the physical properties of cement-asphalt mortar before/after hardening aren't so affected by temperature and well satisfy the requirement. And it has proved that rate of expansion and freezing and thawing resistance aren't affected by temperature.

• International Journal of Concrete Structures and Materials
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• v.9 no.1
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• pp.35-43
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• 2015

The critical element for sustainable growth in the construction industry is the development of alternative cements. A new technological process called geopolymerization provides an innovative solution, and the presence of aluminum and silicon oxides in fly ash has encouraged its use as a source material. Many previous investigations have involved curing the binder in a heated environment. To reduce energy consumption during the synthesis of geopolymers, the present study investigated the properties of ambient cured geopolymer mortar at early ages. An experimental program was executed to establish a relationship between the activator composition and the properties of geopolymer mortar in fresh and hardened states. Concentrations of sodium hydroxide and sodium silicate were ascertained that are advantageous for constructability and mechanical behavior. Scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction techniques were also used to characterize the material. Test results indicate that there is potential for the concrete industry to use fly ash based geopolymer as an alternative to portland cement.

• Carbon letters
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• v.9 no.4
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• pp.298-302
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• 2008

Carbon blacks could be used as the filler for the electromagnetic interference (EMI) shielding. The poly vinyl alcohol (PVA) and polyvinylidene fluoride (PVDF) were used as the matrix for the carbon black fillers. Porous carbon blacks were prepared by $CO_2$ activation. The activation was performed by treating the carbon blacks in $CO_2$ to different degrees of burnoff. During the activation, the enlargement of pore diameters, and development of microporous and mesoporous structures were introduced in the carbon blacks, resulting in an increase of extremely large specific surface areas. The porosity of carbon blacks was an increasing function of the degree of burn-off. The surface area increased from $80\;m^2/g$ to $1142\;m^2/g$ and the total pore volume increased from $0.14073\;cc{\cdot}g^{-1}$ to $0.9343\;cc{\cdot}g^{-1}$. Also, the C=O functional group characterized by aldehydes, ketones, carboxylic acids and esters was enhanced during the activation process. The EMI shielding effectiveness (SE) of raw N330 carbon blacks filled with PVA was about 1 dB and those of the activated carbon blacks increased to the values between 6 and 9 dB. The EMI SE of raw N330 carbon blacks filled with PVDF was about 7 dB and the EMI SE increased to the range from 11 to 15 dB by the activation.

• The Korean Journal of Mycology
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• v.13 no.1
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• pp.49-51
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• 1985

Mycoplasma-like organisms (MLO) were identified from three plants. The disease symptoms show stunting, yellowing and witche's broom on Cnidium officinale Makino collected from Ulreung Island, Bupleurum falcatum L. collected from Jangsu, and Plantago asiatica L. collected from Daegwanreung. The particles of MLO were observed in the phloem tissues by a Hitachi Hu-11E electron microscope. C. officinale infected with MLO was frequently observed in Ulreung Island.

• The Journal of Korean Medicine
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• v.23 no.2
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• pp.78-87
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• 2002

Objectives : The aim of this study was to investigate the effects of Ginseng Radix (Panax ginseng C.A. MEY.), Zizyphi Spinosae Semen (Zizyphus spinosa HU.) and Rehmanniae Radix Preparat (Rehmannia glutinosa LIBOSCH.) on the serotonin- immunoreactivity cells in the Caudal raphe nuclei, Rostal raphe nuclei and hippocampus of the mouse brain. Methods : The mice were stressed by restraining for one hour and treated with herbal medicine by oral feeding. The mice were killed after one hour and observed by electron microscope after immunohistochemical staining. Results : In the caudal raphe nuclei of the medulla oblongata, the highest number of 5-HT immunoreactivity cells were observed at the Zizyphi Spinosae Semen-treated group, while the lowest level among the herbs treatment group was shown at the Ginseng Radix group. In the hippocampus, serotonin-immunoreactive cells were expressed significantly at the CA3 area while the lowest level of it was shown at the control group. In the midbrain, immunoreactive cells were expressed higher than other groups, while observed at the lowest level in the control group. Conclusions : The extracts of Zizyphi Spinosae Semen, Rehmanniae Radix Preparat and Ginseng Radix show a certain degree of effect on the change of serotonin immunoreactive neurons as an index of nerve disorder.

• Korean Journal of Pharmacognosy
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• v.29 no.2
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• pp.79-85
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• 1998

Six antioxidative compounds in the aerial parts of Potentilla fragarioides were isolated by a bioassay guided purification using a DPPH free radical. They were identified as (+)-catechin, isoquercitrin, quercitrin, $quercetin-3-O-{\beta}-D-glucopyranosyl-{\beta}-D-xylopyranoside$, caffeic acid, and 4-O-caffeoyl-L-threonic acid on the basis of $^{1}H$ and $^{13}C-NMR$ and MS data. The DPPH radical scavenging activity of five compounds $(RC_{50}:\;7.5{\sim}10.5\;{\mu}g)$ except for quercitrin $(16\;{\mu}g)$ was more effective than those of ${\alpha}-tocopherol$ $(12\;{\mu}g)$ and BHA $(14\;{\mu}g)$.

• Progress in Superconductivity
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• v.9 no.2
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• pp.140-145
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• 2008

We report on the Josephson vortex dynamics in $Bi_2Sr_2CaCuO_{8+\delta}$ natural Josephson junctions by c-axis tunneling measurements. Beside the quasiparticle branches in the current-voltage characteristics, a new set of multiple branches, referred to as Josephson-vortex-flow branches (JVFBs), are observed. The JVFBs emerge in an in-plane magnetic field above $H_0\;=\;{\Phi}_0/{\gamma}s^2$ and show highly hysteretic behavior, which can be explained in terms of the recently proposed dynamic-phase-separation model. In this work we examined the effect on the JVFBs by the presence of pancake vortices generated as the external magnetic field was applied slightly tilted from the in-plane direction. JVFBs were found to become larger and prominent with increasing pancake vortex density as the tilt angle increased, which were presumably caused by slowing down of a Josephson vortex lattice in the presence of pancake vortices.

• Journal of the Korean Society of Visualization
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• v.9 no.2
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• pp.34-39
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• 2011

This paper presents a novel direct fabrication method of the thin metal film RTD temperature sensor array on an arbitrary curved surface by using MEMS technology to measure a distributed temperature field up to $300^{\circ}C$ without disturbing a fluid flow. In order to overcome the difficulty in the three dimensional photography of sensor patterning, the UV pre-irradiated photosensitive dry film resist technology has been developed newly. This method was applied to the fabrication of the temperature sensor array on a glass tube, which is arranged parallel and transverse to a main flow. Gold was used as a temperature sensing material. The resistance change was measured in a thermally controlled oven by increasing the environmental temperature. The linear increase in resistance change and a constant slope were obtained. Also, the sensitivity of each RTD temperature sensor was evaluated.