• Preventive Nutrition and Food Science
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• v.9 no.1
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• pp.7-13
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• 2004

Lactic acid fermentation of prickly pear extract (PPE) was performed by Lactobacillus rhamnosus LS, Lactobacillus bulgaricus, and Lactobacillus brevis. The PPE was pasteurized to eliminate indigenous microorganisms as well as to dissolve the partially insoluble pulp. The PPE fermented without yeast extract by L. rhamnosus LS exhibited 0.57％ acidity and 3.5${\times}$10$^{8}$ CFU/mL bacteria count. With the addition of 0.2% edible yeast extract the PPE fermented by L. rhamnosus LS exhibited 1.15％ acidity,2.7${\times}$10$^{9}$ CFU/mL bacteria count and 95.0% retention of red color. When 5％ fructose syrup was added, the PPE fermented by L. rhamnosus LS had 1.09% acidity, 6.5${\times}$10$^{8}$ CFU/mL, and 97.7% retention of red color. With 1∼3% (w/v) concentrations of starter, the PPE fermented by L. bulgaricus and L. brevis showed 0.97% and 0.65% acidities, respectively. The viable cell counts from L. rhamnosus LS fermentation were higher compared with those of other LAB. During cold storage at 4$^{\circ}C$, the viable cell count was well maintained for 3 weeks, but then rapidly decreased. The red pigment was highly stable during cold storage for 4 weeks. The pasteurized PPE fortified with 5% fructose syrup, 0.2% yeast extract, and 0.05% CaCO$_3$ was successfully fermented by inoculating with 3% LAB and incubating at 3$0^{\circ}C$ for 2 days. Both viable cell counts and the red color of the fermented PPE were well maintained during cold storage for 3 weeks.

• Journal of Korean Society of Forest Science
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• v.84 no.1
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• pp.41-47
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• 1995

A micropropagation system for black Locust(Robinia pseudoacacia) was established by using shoots and pin-punctured leaves of in vitro germinated seedlings. The greatest number of shoots (an average of 10.5 shoots) was obtained when shoot tips were cultured on MS medium supplemented with 1.0 mg/l BAP and 0.01 mg/l NAA. When pin-punctured leaf explants were cultured on the same medium, mean number of 13.5 shoots were produced. Shoot growth was accelerated by adding 50 mg/l of silver nitrate ($AgNO_3$), an anti-ethylene compound to the culture medium. Each shoot was excised from the mass and transferred onto half strength MS medium for rooting. Zygotic embryos at different developmental stages were cultured on LS medium supplemented with various growth regulators to induce somatic embryos. When cultured on LS medium with 1.0 mg/l 2,4-D. 14.3% of the zygotic embryos induced somatic embryos. Upon transfer onto the basal medium, somatic embryos sporadically converted into plantlets.

• Korean Journal of Materials Research
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• v.15 no.4
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• pp.224-232
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• 2005

Dry sliding wear behavior of electro-pressure sintered Fe-Ni and Co-Fe-Ni compacts was investigated. Pin-on-disk wear tests were performed on the sintered Fe-Ni, Co-Fe-Ni disk specimens against alumina $(Al_2O_3)$ and silica $(SiO_2)$ ball counterparts at various loads ranging from 3N to 12N. A constant sliding speed of 0.1m/sec was employed. Wear rate was calculated by dividing the weight loss measured after the test by specific gravity and sliding distance. Worn surfaces and cross sections of them were examined by a scanning electron microscopy, and wear mechanism of the compacts was investigated. Wear characteristics of the compacts were discussed as a function of composition of the compacts. Relationship between the wear rate and mechancial properties of the compact was explored, and effects of the oxide layer that was formed on wearing surface of the compacts on the wear were also studied.

• Tribology and Lubricants
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• v.21 no.5
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• pp.216-220
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• 2005

The sliding wear behaviors of three different compositions of novel low temperature degradation-free zirconia/alumina (LTD-free Z/A) composites were examined in a ceramic-ceramic contact pair. The wear tests were performed by using a pin-on-disk type wear tester in a linear reciprocal sliding motion with a line contact in both dry and bovine serum lubricated conditions at room temperature. From the results of dry sliding wear tests, Z/A#1((5.3Y, 4.6Nb)-TZP/80 $vol\%Al_2O_3$) showed the best wear resistance among three kinds of LTD-free Z/A composites. For the bovine serum lubricated sliding wear tests, wear was too little to be measured for all kinds of Z/A composites. These novel LTD-free Z/A composites having excellent wear resistance demonstrated a potential as the alternative materials for the ceramic-ceramic contact pairs of femoral head and acetabular liner in total hip replacement.

• Preventive Nutrition and Food Science
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• v.5 no.3
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• pp.165-169
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• 2000

Kombucha beverages were made from sweetened tea by Oriental, European and Tibetan tea fungus starters. The hot water extracts o green tea, black tea, Gugija and Omija were mixed with white and/or brown sugar, and were fermented under a static culture at 3$0^{\circ}C$. Titrable acidity, pH, color and cellulose production in kombucha beverages were evaluated. All tea fungus starters showed a higher acid production in green/black tea extracts rather than Gugija and Omija extracts. In green/black tea extracts Oriental tea fungus produced a kombucha beverage with a higher titrable acidity and lower pH than those of European and Tibetan tea fungus starters. By the static fermentation of green/black tea extract for 18 days, Oriental, Tibetan and European tea fungus starters produced cellulose pellicles of 0.43g, 0.16g, and 0.19 g (dry weight) on the top in the culture, respectively. As a mother starter, the cellulose pellicle was more efficient in acid production compared with tea fungus broth. Oriental/Tibetan mixed tea fungus showed the best acid production in the green/black tea extract supplemented with brown sugar.

• Journal of Powder Materials
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• v.11 no.6 s.47
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• pp.451-461
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• 2004

Dry sliding wear behavior of electro-pressure sintered Co-Fe and Co-Ni compacts was investigated. Pin-on-disk wear tests were performed on the sintered Co-Fe, Co-Ni disks against alumina $(Al_2O_3)$ and silica $(SiO_2)$ balls at various loads ranging from 3N to 12N. A constant sliding speed of 0.1m/sec was employed. Wear rate was calculated by dividing the weight loss of a specimen by the measured specific gravity and sliding dis-tance. Worn surfaces and cross-sections of the specimens were examined using an SEM and EDS to investigate wear mechanism of the compacts. The wear behavior of the compacts were discussed as a function of their com-position. Effects of mechancial properties of the compact as well as oxide layers formed on wearing surface on the wear were also discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2615-2618
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• 2009

Double rectangular patch with 4-bridges is investigated for solution of IEEE 802.11b/g (2.4 GHz) and 802.11a (5.5 GHz). Rectangular patch for 5.5 GHz frequency band is printed on the PCB substrate and connected to another rectangular patch for 2.4 GHz frequency band with 4-bridges to obtain dual band operation in an antenna element. 4-bridges can modify the desired frequency band from its original frequency band by changing its width. Gain of 2.4 GHz patch is 5 dBi and 5.5 GHz patch is 3.7 dBi at ${\theta}=0^{\circ}$.

• Journal of Korean Neurosurgical Society
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• v.48 no.3
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• pp.291-293
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• 2010

We report a case of pseudoaneurysm of the parietal division of the superficial temporal artery (STA) secondary to iatrogenic head injury due to Gardner traction. A 54-year-old man presented with a pulsatile, cystic, and painless mass in the right anterior temporal region which developed three weeks after head fixation via Gardner traction. At the time of discovery, the mass was 10 mm in diameter, compressible and disappeared after manual compression of the proximal STA. A bruit was audible over the mass, which was thought to be a pseudoaneurysm. A computed tomography angiogram (CTA) showed a pseudoaneurysm of the parietal division of the right ST A. The tip of the pseudoaneurysm was thrombosed and was both red and tender. The pseudoaneurysm was thought to be filled with infected thrombus, and the mass was resected with ligation of the proximal and distal ends of the STA. A pseudoaneurysm of the STA should be suspected when there is a history of possible vessel injury, such as a history of head-pin fixation, and when a patient presents with a pulsatile, cystic mass near the temple. Pseudoaneurysms can be successfully treated by excision.

• ETRI Journal
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• v.29 no.4
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• pp.421-429
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• 2007

This paper presents a direct-conversion CMOS transceiver for fully digital DS-UWB systems. The transceiver includes all of the radio building blocks, such as a T/R switch, a low noise amplifier, an I/Q demodulator, a low pass filter, a variable gain amplifier as a receiver, the same receiver blocks as a transmitter including a phase-locked loop (PLL), and a voltage controlled oscillator (VCO). A single-ended-to-differential converter is implemented in the down-conversion mixer and a differential-to-single-ended converter is implemented in the driver amplifier stage. The chip is fabricated on a 9.0 $mm^2$ die using standard 0.18 ${\mu}m$ CMOS technology and a 64-pin MicroLead Frame package. Experimental results show the total current consumption is 143 mA including the PLL and VCO. The chip has a 3.5 dB receiver gain flatness at the 660 MHz bandwidth. These results indicate that the architecture and circuits are adaptable to the implementation of a wideband, low-power, and high-speed wireless personal area network.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.241-246
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• 2018

In this study, we proposed a wideband frequency tunable metamaterial absorber using a switchable ground plane (SGP). We proposed two fire retardant or flame resistant 4 (FR4) substrate structures for the SGP. An SGP is placed at the middle layer, between the top pattern and the bottom ground plane. The SGP can either be made ground or reactive, by switching the PIN diode ON/OFF. As the frequency is determined by the substrate thickness, the frequency can be switched from the SGP. The proposed absorber is demonstrated by full-wave simulations and measurements. When the SGP is turned on, an absorptivity higher than 90% is achieved from 3.5 GHz to 11 GHz. When the SGP is turned off, an absorptivity higher than 90 % is achieved from 1.7 GHz to 5.2 GHz.