• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.6
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• pp.268-273
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• 2014

$Y_2O_3$ ceramic specimens were fabricated from the granular powder, obtained by spray drying process from the slurry. The slurry was prepared by mixing PVA binder, NaOH for Ph control, PEG and $Y_2O_3$ powder. The $Y_2O_3$ specimen was shaped in size of ${\phi}14mm$ and then sintered at $1650^{\circ}C$. The characteristics, microstructure, densities and plasma resistance of the $Y_2O_3$ specimens were investigated with the function of forming pressure and sintering time. $Y_2O_3$ specimens were exposed under the $CHF_3/O_2/Ar$ plasma, the dry etching treatment of specimens was carried out by the physical reaction etching of $Ar^+$ ion beam and the chemical reaction etching of $F^-$ ion decomposed from $CHF_3$. With increasing sintering time, $Y_2O_3$ specimens showed relatively high density and strong resistance in plasma etching test.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.2 s.43
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• pp.41-47
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• 2007

Today lots of investigations on Embedded Passive Technology using materials and chip components have been carried out. We fabricated diplexers with 1005 sized-passives, which were made by burying chips in PCB substrate and surface mounting chip on PCB. 6 passive chips (inductors and capacitors) were used for the frequency divisions of $880\;MHz{\sim}960\;MHz(GSM)$ and $1.71\;GHz{\sim}1.88\;GHz(DCS)$. Two types of diplxer were characterized with Network analyzer. The chip buried diplexer showed extra 5db loss and a little deviation of 0.6GHz at aimed frequency areas, whereas the chip mounted diplexer showed man. 0.86dB loss within GSM field and max. 0.68dB within DCS field respectively. But few degradations were observed after $260^{\circ}C$ for 80min baking and $280^{\circ}C$ for 10sec solder floating.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.897-903
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• 2011

This paper presents a highly linear power amplifier MMIC, having an output power level of about 1 watt, based on InGaP/GaAs hetero-junction bipolar transistor(HBT) technology for the 900 MHz band. The active bias circuit is applied to minimize the effect of temperature variation. Ballast resistors are optimized to prevent a current collapse and a thermal runaway. The fabricated power amplifier exhibited a gain of 17.6 dB, an output P1dB of 30 dBm, and a PAE of 44.9 % at an output P1dB from the one-tone excitation. It also showed a very high OIP3 of 47.3 dBm at an average output power of 20 dBm from the two-tone excitation.

• Composites Research
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• v.29 no.4
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• pp.125-131
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• 2016

In case of CNT mixing with epoxy, epoxy matrix needs to be diluted. This work studied the effect of the dilution condition of epoxy on CNT dispersion. The optimum solvent condition using acetone and DMF was found via mechanical and solubility methods which affects, the epoxy performance. The dispersion using acetone was better than the DMF and thus higher mechanical properties. Four mixing types of CNT particle were performed. To verify the effects of each step between dilution and dispersion, the dispersion between epoxy and CNT was evaluated via the electrical resistance and optical methods. The optimum dispersion was obtained via mechanical test and thermal analysis by DSC. Among four types, the best was to disperse CNT after epoxy and hardeners were diluted respectively.

• Journal of Plant Biotechnology
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• v.36 no.1
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• pp.75-80
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• 2009

In order to develop transgenic sweetpotato plants [Ipomoea batatas (L.) Lam. cv. Yulmi] with enhanced tolerance to oxidative stress, we constructed transformation vectors expressing 2-Cys peroxiredoxin (Prx) gene under the control of the stress-inducible SWPA2 or enhanced 35S promoter (named as SP or EP). Transgenic sweetpotato plants were attempted to generate from embryogenic calli using an Agrobacterium-mediated transformation system. Embryogenic calli gave rise to somatic embryos and then converted into plantlets on MS medium containing 100 mg/L kanamycin. Transgenic plants were regenerated in the same medium. Southern blot analysis confirmed that the Prx gene was inserted into the genome of the plants. To further study we selected the transgenic plant lines with enhanced tolerance against methyl viologen (MV). When sweetpotato leaf discs were subjected to methyl MV at $20{\mu}M$, transgenic plants showed about 40% higher tolerance than non-transgenic or empty vector-transformed plants.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.6
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• pp.585-592
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• 2011

The enhancement of the cold-start capability of polymer electrolyte fuel cells is of great importance in terms of the durability and reliability of fuel-cell vehicles. In this study, vanadium oxide films deposited onto the flat surface of metallic bipolar plates were synthesized to investigate the feasibility of their use as an efficient self-heating source to expedite the temperature rise during startup at subzero temperatures. Samples were prepared through the dip-coating technique using the hydrolytic sol-gel route, and the chemical compositions and microstructures of the films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy. In addition, the electrical resistance hysteresis loop of the films was measured over a temperature range from -20 to $80^{\circ}C$ using a four-terminal technique. Experimentally, it was found that the thermal energy (Joule heating) resulting from self-heating of the films was sufficient to provide the substantial amount of energy required for thawing at subzero temperatures.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.4
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• pp.93-99
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• 2016

In this paper, we investigated the mechanical and electrical reliability of silver nanowire (AgNW) films. In particular, the durability and reliability of AgNW films were studied when the AgNW film was subjected to the bending deformation under current flow. The electrical durability of AgNW was evaluated by observing changes in heat generation and current density occurring in AgNW through voltage and current tests. The AgNW film showed a constant resistance change up to a bending radius of 2 mm and 200,000 cycles in the bending fatigue tests. The over-coating layer has an effect of improving the durability of the AgNW film. In the case of AgNW with the over-coating layer, heat was uniformly dissipated on the surface of AgNW film, whereas in the case of AgNW film without the over-coating layer, heat was generated locally. In the bending test under the current flow, the current density of the AgNW film was continuously decreased up to 52.4%. During bending, the AgNW was deformed due to mechanical deformation such as tensile, bending and sliding of the AgNW, consequently contact resistance of the AgNW was increased, leading to a electrical breakdown of AgNW by Joule heating. It was found that the application of the over-coating layer can improve the electrical and mechanical reliability of the AgNW film.

• Korean Journal of Food Science and Technology
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• v.52 no.4
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• pp.396-402
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• 2020

In order to investigate the changes in the quality attributes during the storage of dry-milled rice flour, two flour samples were obtained from two rice varieties (Hangaru (HG), Samkwang (SK)). These samples were stored at 4℃ and room temperature, respectively, and we analyzed the initial rice flour moisture content and chemical properties. The changes in the rice flour pasting and quality properties during storage were measured for 12 months. Our results showed that HG exhibited better pasting properties than SK, while the fat acidity of HG rapidly increased at room temperature, resulting in short shelf-life. However, the low-temperature (4℃) storage of dry-milled rice flour could reduce the change in the free fatty acid values of both samples. Therefore, low-temperature storage seems to contribute not only to an increased rice flour shelf-life by reducing the fatty acid value changes but also to a reduction in the changes in pasting properties.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.1
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• pp.47-56
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• 2020

Purpose : The purpose of this study was to determine the effects of upper extremity volume, pain, and range of motion after participation in thera-band exercises according to the hand grip type in patients with breast cancer with upper extremity edema. We also aimed to determine the most efficient type of grip. Methods : The subjects were 10 female patients diagnosed with stage 2 breast cancer who had stage 2 lymphedema. Randomly, 5 patients each were allocated to the experimental and control groups. For six weeks, the patients in both the experimental and control groups exercised daily. In both groups, manual lymph drainage was applied for 1 hour. Afterward, patients in the experimental group placed their hands in the thera-band ring and exercised with their fingers outstretched. Patients in the control group exercised while holding the thera-band ring with a finger. Both the experimental group and the control group underwent measurements of the circumference of the upper extremity, pain, and range of motion of the shoulder joint at weeks 1, 2, 4, and 6 before and after exercise. Results : The upper arm circumference decreased by more in the experimental group in all weeks than before than that in the control group, and there was a statistically significant difference at 6 weeks. Compared with the difference between pre-exercise and 6 weeks post-exercise, the change in pain significantly decreased in the experimental group and showed a statistically significant difference. The shoulder range of motion increased in extension, external rotation, and internal rotation compared with that in the control group, and there was a statistically significant difference. Although the operating range increased in flexion and abduction, there were no statistically significant differences. Conclusion : In this study, we found that thera-band exercises with an open-hand grip are more efficient than thera-band exercises with a closed-hand grip in edema reduction, pain, and range of motion. In addition, it was found that it was more effective to continue the thera-band exercises with open-hand grip extended for at least 6 weeks rather than for a short time.

• Research in Plant Disease
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• v.10 no.1
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• pp.58-62
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• 2004

Contamination level and characteristics of Ralstonia solanacearum in soil of greenhouses cultivating tomato plants in Chungbuk province was determined. R. solanacearum was isolated with the semiselective media in 27 greenhouse soil samples out of 133 greenhouses soil investigated, which indicates 20.3 ％ of tomato cultivating greenhouses in Chungbuk contaminated with the bacterial wilt pathogen. Density of R. solanacearum was estimated to 10$^{2.4}$ cfu/g in the contaminated soil. All 71 isolates of R. solanacearum which containing 12 isolates from the diseased tomato plants were race 1, ann 35 isolates of them were biovar 3 and 36 isolates were biovar 4. More than 88％ of 71 isolates were inhibited growth on nutrient agar containing oxolinic acid 0.5 $\mu\textrm{g}$/ml, streptomycin 25 $\mu\textrm{g}$/ml, tetracycline 5 $\mu\textrm{g}$/ml and cupric sulfate 375 $\mu\textrm{g}$/ml (1.5 mM). The 11.3％, 4.2％ and 5.6 ％ of the isolates can grow on nutrient agar containing 10 times more oxolinic acid, streptomycin, tetracycline than minimal inhibitory concentration of the sensitive strains. Five isolates were resistant to 2 bactericides and one isolates was resistant to all 3 bactericides.