• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.76-79
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• 2016

This paper describes the successful development and the performance of X-band 50 W pulsed power amplifier using a 50 W GaN-on-SiC high electron mobility transistor. The GaN HEMT with a gate length of $0.25{\mu}m$ and a total gate width of 12 mm were fabricated. The X-band pulsed power amplifier exhibited an output power of 50 W with a power gain of 6 dB in a frequency range of 9.2~9.5 GHz. It also shows a maximum output power density of 4.16 W/mm. This 50 W GaN HEMT and X-band 50 W pulsed power amplifier are suitable for the radar systems and related applications in X-band.

• Journal of Life Science
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• v.26 no.10
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• pp.1196-1201
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• 2016

The ovary parts of Nelumbo nucifera were extracted in 80% methanol (MeOH), and the concentrated extract was then partitioned using n-hexane, ethyl acetate (EtOAc), n-butanol (n-BuOH), and H₂O, successively. Using an octadecyl silica gel (ODS) column, silica gel (SiO₂) column chromatography, and a HPLC purification system, five compounds were isolated from the n-hexane fraction obtained from the extract of N. nucifera ovary. The chemical structures of the metabolites were determined using several spectroscopic methods, including NMR and GC/MS and MS of 1-eicosanol (1), cycloartenol (2), trans-squalene (3), pentadecanoic acid (4), and β-sitosterol (5). This study is a first attempt to isolate and identify secondary metabolites from the ovary of N. nucifera. The results indicated that the extract of N. nucifera ovary has biological effects, such as antibacterial and -tumor activity. Therefore, it could decrease the risk of HIV transmission through breastfeeding.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.4
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• pp.425-432
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• 2016

In addition to classical synaptic transmission, information is transmitted between cells via the activation of extrasynaptic receptors that generate persistent tonic current in the brain. While growing evidence supports the presence of tonic NMDA current ($I_{NMDA}$) generated by extrasynaptic NMDA receptors (eNMDARs), the functional significance of tonic $I_{NMDA}$ in various brain regions remains poorly understood. Here, we demonstrate that activation of eNMDARs that generate INMDA facilitates the ${\alpha}$-amino-3-hydroxy-5-methylisoxazole-4-proprionate receptor (AMPAR)-mediated steady-state current in supraoptic nucleus (SON) magnocellular neurosecretory cells (MNCs). In $low-Mg^{2+}$ artificial cerebrospinal fluid (aCSF), glutamate induced an inward shift in $I_{holding}$ ($I_{GLU}$) at a holding potential ($V_{holding}$) of -70 mV which was partly blocked by an AMPAR antagonist, NBQX. NBQX-sensitive $I_{GLU}$ was observed even in normal aCSF at $V_{holding}$ of -40 mV or -20 mV. $I_{GLU}$ was completely abolished by pretreatment with an NMDAR blocker, AP5, under all tested conditions. AMPA induced a reproducible inward shift in $I_{holding}$ ($I_{AMPA}$) in SON MNCs. Pretreatment with AP5 attenuated $I_{AMPA}$ amplitudes to ~60% of the control levels in $low-Mg^{2+}$ aCSF, but not in normal aCSF at $V_{holding}$ of -70 mV. $I_{AMPA}$ attenuation by AP5 was also prominent in normal aCSF at depolarized holding potentials. Memantine, an eNMDAR blocker, mimicked the AP5-induced $I_{AMPA}$ attenuation in SON MNCs. Finally, chronic dehydration did not affect $I_{AMPA}$ attenuation by AP5 in the neurons. These results suggest that tonic $I_{NMDA}$, mediated by eNMDAR, facilitates AMPAR function, changing the postsynaptic response to its agonists in normal and osmotically challenged SON MNCs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.180-185
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• 1999

Rotating Biological Contactor (RBC) was tested for the treatment of artificial rearing water in n simulated aquaculture system. Performance of RBC on the removal of TAN and COD was evaluated by controlling hydraulic residence time (HRT). As HRT of RBC was increased, TAN removal rate ana removal efficiency of RBC and TAN concentration of rearing water were increased, but COD removal rate was decreased. Total alkalinity consumption rate was increased by increasing HRT of RBC. Ratio between total alkalinity consumption rate and TAN removal rate was 7.73. HRT for maintaining lowest TAN and COD concentration of artificial rearing water was 14,6 minutes and at that condition TAN and COD concentration of the water was 1.28 and $5.59 g/m^3$, respectively.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.2
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• pp.112-116
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• 2012

Purpose: This study attempts to compare the stability of hydroxy-apatite coating implant with that of sandblasted, large-grit and acid-etched surface implant at an early state of installation. Methods: 35 implants were installed in 18 patients, who had visited hospital for implant installation. The early stability at operation, 6 weeks and 12 weeks after operation using Osstell$^{TM}$ mentor (Integration Diagnostics, Savedalen, Sweden) and Periotest$^{(R)}$ (Siemens AG, Benssheim, Germany) were measured, and subsequently analyzed statistically. Results: OsstellTM mentor value of hydroxy-apatite coated implant (HAPTITE) was measured as $70.14{\pm}9.07$ at the stage of installation, $76.98{\pm}5.25$ at 6 weeks and $80.28{\pm}4.23$ at 12 weeks after installation. A statistically significant increase in measurement value was observed after 6 weeks and 12 weeks than when implants were placed. In case of IMPLANTIUM (DENTIUM Co. Ltd., Seoul, Korea), the measurement value was $74.68{\pm}7.42$ at installation, $79.03{\pm}4.39$ at 6 weeks and $80.59{\pm}3.59$ at 12 weeks after installation. In addition, a statistically significant increase in the value was observed when comparative analysis of the value at after installation and 12 weeks after installation was carried out. However, no significant difference between HAPTITE and IMPLANTIUM was observed. The average measurement value of periotest$^{(R)}$ was $-1.94{\pm}3.90$ at installation of HAPTITE, $-4.03{\pm}1.48$ at 6 weeks and $-5.00{\pm}1.71$ at 12 weeks after installation. Moreover, whilst comparing the value at after installation and 12 weeks after installation, statistically significant decrease in the value was observed. In case of IMPLANTIUM, the average measurement value was measured as $-4.25{\pm}1.76$ at installation, $-4.76{\pm}0.97$ at 6 weeks and $-5.18{\pm}0.91$ at 12 weeks after installation and no statistically significant difference was observed. Furthermore, no statistically significant difference was observed between HAPTITE and IMPLANTIUM. Conclusion: In this study, both the implants demonstrated favorable early stability at the time of measurement using Osstell$^{TM}$ mentor and Periotest$^{(R)}$. Moreover, based on the observed results, both HAPTITE and IMPLANTIUM are considered as potent to exhibit clinically stable and prognostic results.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.89-112
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• 2002

The earliest reports of the use of electrical energy to directly stimulate bone healing seem to be in 1853 from England, the techniques involved the introduction of direct current into the non-united fracture site percutaneously via metallic needles, with subsequent healing of the defect. One endpoint of the periodontal therapy is to generate structure lost by periodontal diseases. Several procedural advances may support regeneration of attachment, however, regeneration of alveolar bone does not occur consistently. Therefore, factors which stimulate bone repair are areas for research in periodontal reconstructive therapy. Effects of cytokines or growth factors on bone repair are examples of such areas. Another one is electrical current which occurs in bone naturally, so that such bone may be particularly susceptible to electrical therapy. The purposes of this study were to observe the effects of electrical stimulation on the normal periodontium, to determine whether the electricity is the useful means for periodontal regeneration or not. Forty rats weighted about 100 gram were used and divided into 4 groups, the first group, there was no electrical stimulation with the connection of electrodes only. In the second group, there was stimulated by the 10 mA during 10 minutes per a day, in the third group was stimulated by the 25 mA , and the fourth by the 50 mA. At 3, 5, 10 and 15 days post-appliance , two rats in each group were serially sacrificed. and the maxillae and the mandible processed to paraffin, and the specimens were prepared with Hematoxylin-Eosin stain for the light microscopic evaluation. The results of this study were as follows : 1. There was the distinct reversal line on the lingual alveolar crest, whereas a little changes in the labial alveolarcrest to the duration and amount of currents. 2. In 50 mA group, the cells were highly concentrated at the apex of anterior teeth, and was observed the necrotic tissue. In posterior root apex, the hypercementosis was appeared, and newly formed cementum layer has been increased continuously with the time. 3. The periodontal ligament fiber and Sharpey's fiber were arranged in order, and the bone trabeculae were increased as the experiment proceeded by, relatively the bone marrows were decreased. 4. In the pulp tissue, the blood vessels were increased with blood congestion in the experimetal specimens remarkably, and the dentinal tubules were obstructed . 5. The osteoblasts in alveolar bone proper had been showed highly activity, and also observed the formation of bone trabeculea. In the conclusion, it was suggested that the electrical stimulation has influence on the periodontium and the pulp tissue. However, there might be the injurious effects.

• Journal of Periodontal and Implant Science
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• v.30 no.4
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• pp.757-779
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• 2000

The aim of our study is to achieve complete periodontal tissue regeneration by the application of BMP and resorbable membrane. Three beagle dogs aged over one and half years and weighed 14 to 16 kg were used in this study. Mandibular 1st, 2nd premolars were extracted bilaterally. Horizontal furcation defects were induced around 3rd, 4th premolars bilaterally. BMP-4 were applied in the right side with resorbable membranes and only resorbable membranes were applied in the left side respectively. Each animal was sacrificed at 2, 4, and 8weeks, after regenerative surgery. Specimens were prepared with Hematoxylin-Eosin stain and Goldner's modified Masson Trichrome stain for light microscopic evaluation. The results were as follows: 1. At 2 weeks after regenerative surgery, downgrowth of junctional epithelium was observed both in the membraneapplied site and BMP-4-and-membrane-applied site. 2. At 4 weeks after regenerative surgery, resorbable membranes were completely resolved, therefore would not prevent downgrowth of junctional epithelium. New bone formation, new cementum formation and Sharpey's fiber were observed in BMP-4-andmembrane-applied site. 3. At 8 weeks after regenerative surgery, downgrowth of junctional epithelium was observed in the membrane-applied site. But, new cementum formation was observed in the same site. The extensive regeneration of new bone, new cementum and remarkable formation of Shapey's fiber were showed in BMP-4-and-membrane-applied site. 4. Resorbable membranes were resolved via the cell-mediated processes. 5. Periodontal tissue regeneration were better achieved in the BMP-4-andmembrane-applied site than in the membrane-applied site. Within the above results, BMP-4 may have the strong capability to form the new bone and resorbable membrane may be able to prevent the bony ankylosis. However, resolution rate of resorbable membrane may not be enough to protect rapid epithelial downgrowth for ideal periodontal regeneration. In conclusion, I suggest BMP-4 may have the strong possibility to be utilized in the clinical periodontal treat-

• Journal of Periodontal and Implant Science
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• v.26 no.2
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• pp.531-541
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• 1996

Periodontal disease is characterized by destruction of supporting tissues caused by invasion of plaque bacteria and defense mechanism of host. Many dentists are very interested in laser therapy on various intraoral soft tissue lesions including inflammatory periodontal pocket. In order to determine the therapeutic effect of intrapocket irradiation of a pulsed- Nd : YAG laser on the inflammatory periodontal pockets, bilateral 60 teeth with 4-6mm in probing pocket depth and gingival inflammation were selected and evaluated by sulcus bleeding index(SBI), and plaque index(pI) for baseline record. Intrapocket irradiation($300{\mu}m$ fiber optic, I.5W power, for 2 min.) of a pulsed-Nd : YAG laser(EL.EN.EN060, Italy) was applied on half of them. As the control group, the same procedure except power-off was repeated on the contralateral 30 teeth. At 1-, 2-, 3-, and 4-week after intrapocket manipulation, every tooth was reevaluated by the same clinical indices. And the difference between the lased group and control group was statistically analyzed by paired t-test and Chi-square test in Microstat program. Following results were obtained: 1. Until I-week and 2-week after intrapocket manipulation, SBI was lowered in both lased group and control group, compared to baseline SBI, but from 3-week after, the recovering tendency toward baseline was noted, and at only 2-week after, the number of teeth showing lowered SBI was significantly more in lased group than in control group(p<0.05). 2. PI of both lased group and control group was lowered through whole experimental period from I-week to 4-week after, compared to baseline PI(p<0.05), but there was no significant difference between lased group and control group(p>0.1). The results suggest that intrapocket irradiation of a pulsed-Nd:YAG laser may lead somewhat remission of gingival inflammation, but for more favorable therapeutic result the thorough root planing should be necessarily accompanied with gingival curettage.

• Tuberculosis and Respiratory Diseases
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• v.49 no.2
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• pp.246-252
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• 2000

Lymphangioleiomyomatosis(LAM) is a rare disease of unknown etiology that occurs mainly in woman in her reproductive age. We recently experienced two cases of bilateral diffuse cystic lesion of the lung on chest X-ray and HRCT. The first case, a 26-year-old female, who had been diagnosed with tuberous sclerosis by the presence of clinical manifestation such as mental retardation, bilateral renal angiomyolipoma, adenoma sebaceum and generalized seizure, was admitted due to a recently developed hemoptysis. Chest PA showed diffuse ground-glass opacity with radiolucent cystic lesions of various sizes on both lung fields. HRCT showed innumerable small cystic lesions with suspicious diffuse ground-glass opacity on both lung fields The second case, a 30-year-old fema1e was admitted due to dyspnea and spewing of blood-tinged sputum for 2 weeks, shortly after delivery. Chest PA showed diffuse reticular and ground-glass opacities on both lung field. HRCT showed multiple well-defined and relatively uniform size air cysts with a uniform wall thickness on entire both lung fields, with small amount of right pleural effusion. By thoracoscopic lung biopsy she was diagnosed with pulmonary lymphangioleiomyomatosis. We report these cases with a brief review of the literatures.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.8
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• pp.1079-1085
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• 2011

We investigated the biological activities of extracts from the flowers of Angelica gigas Nakai. The $IC_{50}$ of the DPPH radical scavenging activity was 3,535 and 105.0 ${\mu}g/mL$ in the water and ethanol extracts, respectively, whereas it was 12.7 ${\mu}g/mL$ for ascorbic acid. The results showed that the total polyphenol content of the ethanol extracts (48.43${\pm}$0.18 mg/g) was higher than that of the water extracts (39.03${\pm}$0.69 mg/g). The flavonoid content of the ethanol extracts (67.02${\pm}$4.38 mg/g) was higher than that of the water extracts (50.32${\pm}$1.24 mg/g). The ethanol extract showed a 34.45% lower ${\alpha}$-glucosidase inhibition activity than that for acarbose. The ethanol extract showed a 23.62% lower ${\alpha}$-amylase inhibition activity compared with that for acarbose. The water extract showed 16.76% lower pancreatic lipase inhibition activity. Anti-cancer and anti-inflammatory activity was also lower. These results suggest that the flower of Angelica gigas Nakai may be useful as an anti-oxidative agent.