• Journal of Advanced Marine Engineering and Technology
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• v.22 no.5
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• pp.617-625
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• 1998

A passive energy recovery snubber for high-power-factor boost rectifier, in which the main switch is implemented with a MOSFET, is described in terms of the equivalent circuits that are operational during turn-on and turn-off sequences. These equivalent circuits are analyzed so that the overshoot voltage across the main switch, the snubber current, and the turn-off transition time can be predicted analytically. From these results, the normalized overshoot voltage is reduced to 1 as $_W2T_on$ varies from zero to $\pi$/2, and then it is fIxed at 1 for $_W2T_on$> $\pi$/2. The peak snubber inductor current is directly proportional to the input current. The turn-offtransition time wltoffvaries from 0 to 2.57, depending on $_W2T_on$. The main switch combined with proposed snubber can be turned on with zero current and turned off at limited voltage stress. The high-power-factor boost rectifier with proposed snubber is implemented, and the experimental results are presented to confirm the validity of proposed snubber.

• Herbal Formula Science
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• v.26 no.3
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• pp.207-221
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• 2018

Objectives : Present study investigated hepatoprotective effect of Haegan-jeon extract (HE) and tried to elucidate molecular mechanism involved. According to molecular mechanism, present study optimized herbal composition of HE (op-HE) and compared in vitro and in vivo hepatoprotective effects of op-HE to HE. Methods : For in vitro experiments, HepG2 cells were exposed to arachidonic acid (AA, $10{\mu}M$) and iron ($5{\mu}M$) for inducing oxidative stress. Cell viability, GSH contents, $H_2O_2$ production, mitochondrial membrane potential, immunoblot and reporter gene assay were performed to investigate cytoprotective effects and responsible molecular mechanisms. For in vivo experiments, hepatoprotective effect of HE and op-HE were assessed on $CCl_4-induced$ liver injury mice model. Results : HE pretreatment prevented AA+iron-mediated hepatocytes apoptosis. In addition, AA+iron-induced mitochondrial dysfunction, $H_2O_2$ production, glutathione depletion were reduced by HE pretreatment. In addition, nuclear factor erythroid 2-related factor 2 (Nrf2) phosphorylation, antioxidant response element (ARE)-driven reporter gene activity, and antioxidant genes expression were increased by HE. Based on reporter gene and MTT assays, we found that op-HE consisting three medicinal herbs also significantly increased transactivation of Nrf2 and reduced the AA+iron-mediated cytotoxicity. Moreover, in $CCl_4-induced$ liver injury mice model, HE-op had an ability to ameliorate $CCl_4-mediated$ increases in serum alanine transferase and aspartate aminotransferase activity, hepatic degeneration, inflammatory cell infiltration, and collagen deposition. Hepatoprotective effects of op-HE were comparable to those of HE. Conclusions : Present study suggests that op-HE as well as HE exhibit hepatoprotective effect against oxidative stress-mediated liver injury via Nrf2 activation.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.3
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• pp.193-201
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• 2006

Squamous cell carcinoma(SCC) of head and neck(SCCHN) is the sixth most common human malignant tumor. However, despite advances in prevention and treatment of SCC, the five-year survival rates for patients remain still low. To improve the outcome for patients with SCCHN, novel treatment strategies are needed. Overexpression of the epidermal growth factor(EGF) and activation of its receptor(EGFR) are associated with progressive growth of SCCHN. Vascular endothelial growth factor(VEGF) signaling molecules are related with neoangiogenesis and vascular metastasis of SCC. In this study, we determined the therapeutic effect of AEE788(Novartis Pharma AG, Basel, Switzerland), which is a dual inhibitor of EGFR/ErbB2 and VEGFR tyrosine kinases, on human oral SCC. At first, we screened the expression of EGFR, c-ErbB2(HER-2) and VEGFR-2 in a series of human oral SCC cell lines. And then we evaluated the effects of AEE788 on the phosphorylation of EGFR and VEGFR-2 in a oral SCC cell line expressing EGFR/HER-2 and VEGFR-2. We also evaluated the effects of AEE788 alone, or with paclitaxel(Taxol) on the oral SCC cell growth and apoptosis. As a result, all oral SCC cells expressed EGFR and VEGFR-2. Treatment of oral SCC cells with AEE788 led to dose-dependent inhibition of EGFR and VEGFR-2 phosphorylation, growth inhibition, and induction of apoptosis. Moreover, AEE788 sensitizes the cells to paclitaxel-mediated toxicity and apoptosis. These data mean EGFR and VEGFR-2 can be reliable targets for molecular therapy of oral SCC, and therefore warrant clinical use of EGFR/VEGFR inhibition in the treatment of patients with recurrent or metastatic oral SCC.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.14
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• pp.5647-5654
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• 2015

Gall bladder cancer (GBC) is a gastro-intestinal cancer with high prevalence among north Indian women. Platelet derived growth factor-B (PDGFB) and human epidermal growth factor receptor-2 (HER2) may play roles in the etiology of GBC through the inflammation-hyperplasia-dysplasia-carcinoma pathway. To study the association of PDGFB and HER2 polymorphisms with risk of GBC, 200 cases and 300 controls were considered. PDGFB +286A>G and +1135A>C polymorphisms were investigated with an amplification refractory mutation system and the HER2 $Ile^{655}Val$ polymorphism by restriction fragment length polymorphism. Significant risk associations for PDGFB +286 GG (OR=5.25) and PDGFB +1135 CC (OR=3.19) genotypes were observed for GBC. Gender wise stratification revealed susceptibility for recessive models of PDGFB +1135A>C (OR=3.00) and HER2 $Ile^{655}Val$ (OR=2.52) polymorphisms among female GBC cases. GBC cases with gall stones were predisposed to homozygous +286 GG and +1135 CC genotypes. Significant risk associations were found for ACIle (OR=1.48), GAVal (OR=1.70), GAIle (OR=2.00) haplotypes with GBC cases and GCIle haplotype with female GBC cases (OR=10.37, P=<0.0001). Pair-wise linkage disequilibrium revealed negative associations among variant alleles. On multi-dimensional reduction analysis, a three factor model revealed significant gene-gene interaction for PDGFB +286A>G, PDGFB +1135A>C and HER2 Ile165Val SNPs with GBC. Protein-protein interaction showed significant association of PDGFB and HER2 with the epidermal growth factor receptor signaling pathway.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.4
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• pp.137-143
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• 2010

This paper deals with the performance comparison of self adaptive equalizer by the weighting factor of MCMA cost function for the compensate the amplitude and phase distortion which occurs in the communication channel. The MCMA is improves the cost function of present CMA at the output of equalizer for the minimize of error function in the amplitude and phase, the value of weighting factor is used at this time. When the comparison of equalizer performance, we classified to initial state and steady state, then it represents the convergence time and convergence speed and steady state operation of equalizer to the predetermined level, it is determined by the weighting factor. We confirm to the different result to this 2 state by weighting factor values using computer simulation. By using the result of this paper, if we appropriately choose the weighting factor values in the environment of communication channel, it is expected that the high quality digital transmission is possible.

• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.265-272
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• 2016

Objective: The aim of this study was to analyze X-factor, triple X-factor, and the center of pressure (COP) according to the feel of golf driver swing. Method: For this research, 9 golfers from the Korea Professional Golfers' Association (age: $30.11{\pm}2.98yrs$, height: $178.00{\pm}8.42cm$, weight: $76.22{\pm}8.42kg$, experience: $10.06{\pm}3.11yrs$) were recruited to participate in the experiment. Twelve Motion Analysis Eagle-4 cameras were installed and an image analysis was conducted by using the NLT (non-linear transformation) method, and 2 units of Kistler type 5233A dynamometer were used to measure ground reaction force. The sampling ratio was set at 1000 Hz. The golfers each took 10 swings by using their own driver, and chose the best and worse feel from among 10 shots. A paired-sample t-test was used to analyze the results. Results: In regard to feel, no change in head speed, X-factor, and the triple X-factor's X-factor stretch, hip rise, and head swivel, was observed (p>.05). Regarding ground reaction force, a difference was observed between the top of the backswing (p<.05) and impact (p<.05) in the vertical force of the left foot. For COP, a difference was also observed between the mid backswing (p<.001), late backswing (p<.001), and top of the backswing (p<.05) for the right foot X-axis and Y-axis mid follow through (p<.01). Conclusion: It can be reasoned that, irrespective of feel, the head speed, X-factor and triple X-factor's X-factor stretch, hip rise and head swivel did not have an effect on drive distance for domestic golfers, and the vertical reaction force of the left foot and left-right movement span's pressure dispersal of the right foot had an increasing effect on drive distance.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.25 no.2
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• pp.12-17
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• 2017

Manned aircraft structural design is based on structural safety factor of 1.5, and this safety factor is equivalent to a probability of failure of between 10-2 and 10-3. The target failure probability of FARs is between 10-6 and 10-9 per flight according to aircraft type. NATO released STANAG 4703 to established the airworthiness requirements for small UAV which is less than 150kg. STANAG 4703 requires the Target Level of Safety according to MTOW. The requirements of failure probability for small UAV is between 10-4 and 10-5. In this paper, requirements of airworthiness certification for small UAV were investigated and the relationship of safety factors to the probability of structural failure is analyzed to reduce measure of safety factor and structural weight of unmanned aircraft.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.148-155
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• 1998

A novel single-switch, single-stage, AC/DC forward converter with transformer magnetic energy feedback technique for power factor correction is proposed. The operational principle and analysis of the proposed converter is presented. The proposed converter gives the good power factor correction, low line current harmonic distortions, and tight output voltage regulation. The prototype shows the IEC 555-2 requirements are met satisfactorily with nearly unity power factor.

• Journal of muscle and joint health
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• v.5 no.2
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• pp.206-221
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• 1998

The purpose of this study was to validate translated Multidimensional Assessment of Fatigue(MAF) scale. The scale is a 16-item scale that measures four dimensions of fatigue : severity, distress, impact, timing. Fourteen items are numerical rating scales and 2 items have multiple choice responses. Data were collected from the 137 patients with rheumatoid arthritis after content validation. Criterion validity was tested by correlation coefficient with Piper Fatigue Scale, which resulted in 0.7573(p<.0000). Construct validity was tested by item analysis and factor analysis. Corrected item-total correlation coefficients were 0.63-0.88. And factor analysis showed 2 factors : fatigue degree factor and fatigue impact factor. These two factors explained 73.5% of total variance. Reliability of internal consistency was 0.96 in Cronbach's alpha. Further validation study is necessary in each factor in other settings with other subjects.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.219-220
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• 2006

In this study, m order to develop multilayer ceramics vibrator for ultrasonic nozzle, PMN-PNN-PZT ceramics were fabricated using $Li_2CO_3-Na_2CO_3$ as sintering aids and their piezoelectric and dielectric characteristics were investigated according to the aomunt of PbO. With increasing PbO contents. secondary phases were increased and phase structure were changed from tetragonal structure to rhombohedral structure and also electromechanical coupling factor were linearly decreased. At the composition ceramics with the sintering temperature of $870^{\circ}C$ and 1 mol% excess PbO, density, electromechanical coupling factor, dielectric constant, piezoelectric d constant and mechanical quality factor showed the optimum value of $7.879g/cm^2$, 0.55, 1149, 328pC/N, 1224, respectively for multilayer ceramics vibrator application for ultrasonic nozzle.