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Search Results: 1 - 10 of 37112 matches for " Dong You Choi "
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Comparative Study of Antenna Designs for RF Energy Harvesting
Sika Shrestha,Sun-Kuk Noh,Dong-You Choi
International Journal of Antennas and Propagation , 2013, DOI: 10.1155/2013/385260
Comparison of Measured Rain Attenuation in the 12.25?GHz Band with Predictions by the ITU-R Model
Dong You Choi,Jae Young Pyun,Sun Kuh Noh,Sang Woong Lee
International Journal of Antennas and Propagation , 2012, DOI: 10.1155/2012/415398
Abstract: Quantitative analysis and prediction of radio attenuation is necessary in order to improve the reliability of satellite-earth communication links and for economically efficient design. For this reason, many countries have made efforts to develop their own rain attenuation prediction models that are suited to their rain environment. In this paper, we present the results of measurements of rain-induced attenuation in vertically polarized signals propagating at 12.25 GHz during certain rain events, which occurred in the rainy wet season of 2001 and 2007 at Yong-in, Korea. The rain attenuation over the link path was measured experimentally and compared with the attenuation obtained using the ITU-R model.
ATF3 Plays a Key Role in Kdo2-Lipid A-Induced TLR4-Dependent Gene Expression via NF-κB Activation
Eun-Young Kim,Hye Young Shin,Joo-Young Kim,Dong-Gun Kim,Yong-Min Choi,Hyuk-Kwon Kwon,Dong-Kwon Rhee,You-Sun Kim,Sangdun Choi
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0014181
Abstract: Activating transcription factor 3 (ATF3) is a negative regulator of proinflammatory cytokine expression in macrophages, and ATF3 deficient mice are more susceptible to endotoxic shock. This study addresses the role of ATF3 in the Kdo2-Lipid A-induced Toll-like receptor 4 (TLR4) signaling pathway in mouse embryonic fibroblasts (MEF). Kdo2-Lipid A upregulates ATF3 expression in wild type MEF cells and induces both nuclear factor kappa B (NF-κB) and c-Jun N-terminal kinase (JNK) activation via the TLR4 signaling pathway, while neither of these pathways is activated in ATF3-/- MEF cells. Interestingly, in contrast to Kdo2-Lipid A, the activation of both NF-κB and JNK by TNF-α was normal in ATF3-/- MEF cells.
Measurement of Blood Pressure Using an Arterial Pulsimeter Equipped with a Hall Device
Sang-Suk Lee,Dong-Hyun Nam,You-Sik Hong,Woo-Beom Lee,Il-Ho Son,Keun-Ho Kim,Jong-Gu Choi
Sensors , 2011, DOI: 10.3390/s110201784
Abstract: To measure precise blood pressure (BP) and pulse rate without using a cuff, we have developed an arterial pulsimeter consisting of a small, portable apparatus incorporating a Hall device. Regression analysis of the pulse wave measured during testing of the arterial pulsimeter was conducted using two equations of the BP algorithm. The estimated values of BP obtained by the cuffless arterial pulsimeter over 5 s were compared with values obtained using electronic or liquid mercury BP meters. The standard deviation between the estimated values and the measured values for systolic and diastolic BP were 8.3 and 4.9, respectively, which are close to the range of values of the BP International Standard. Detailed analysis of the pulse wave measured by the cuffless radial artery pulsimeter by detecting changes in the magnetic field can be used to develop a new diagnostic algorithm for BP, which can be applied to new medical apparatus such as the radial artery pulsimeter.
Severe thrombocytopenia before liver transplantation is associated with delayed recovery of thrombocytopenia regardless of donor type
Jae Hyuck Chang, Jong Young Choi, Hyun Young Woo, Jung Hyun Kwon, Chan Ran You, Si Hyun Bae, Seung Kew Yoon, Myung-Gyu Choi, In-Sik Chung, Dong Goo Kim
World Journal of Gastroenterology , 2008,
Abstract: AIM: To compare the recovery of thrombocytopenia and splenomegaly during long-term follow-up after liver transplantation in patients receiving a living donor transplant or a cadaveric donor transplant.METHODS: This was a retrospective cohort study of 216 consecutive liver transplant patients who survived for > 6 mo after transplantation; 169 received a liver transplant from a living donor and 47 from a cadaveric donor. The platelet counts or spleen volumes were examined before transplant, 1, 6, and 12 mo after transplant, and then annually until 5 years after transplant.RESULTS: The mean follow-up period was 49 mo (range, 21-66). Platelet counts increased continuously for 5 years after orthotopic liver transplant. The restoration of platelet counts after transplant was significantly slower in patients with severe pretransplant thrombocytopenia (< 50 000/μL) until 4 years after transplant (P = 0.005). Donor type did not significantly affect the recovery of platelet count and spleen volume in either patient group. In multivariate analysis, pretransplant severe thrombocytopenia (< 50 000/μL) was an independent factor associated with sustained thrombocytopenia (P < 0.001, odds ratio 6.314; confidence interval, 2.828-14.095). Thrombocytopenia reappeared after transplant in seven patients with portal flow disturbance near the anastomosis site.CONCLUSION: Our study suggests that severe thrombocytopenia before transplant is closely associated with delayed recovery of platelet count after transplant and donor type did not affect the recovery of thrombocytopenia. The reappearance of thrombocytopenia after transplant should be considered a possible indicator of flow disturbance in the portal vein.
Antibacterial Activity of Methyl Gallate Isolated from Galla Rhois or Carvacrol Combined with Nalidixic Acid Against Nalidixic Acid Resistant Bacteria
Jang-Gi Choi,Ok-Hwa Kang,Young-Seob Lee,You-Chang Oh,Hee-Sung Chae,Hye-Jin Jang,Dong-Won Shin,Dong-Yeul Kwon
Molecules , 2009, DOI: 10.3390/molecules14051773
Abstract: Methyl gallate is a major component of Galla Rhois, as carvacrol is of oregano essential oils. Both have shown good antibacterial activity against intestinal bacteria. This study investigated the antibacterial activities of nalidixic acid in combination with methyl gallate and carvacrol against nalidixic acid resistant bacteria. The combined effect of nalidixic acid with methyl gallate and carvacrol was evaluated using the checkerboard method to obtain a fractional inhibitory concentration index. The results showed that the combinations of nalidixic acid + methyl gallate/carvacrol improved nalidixic acid resistant pathogenic bacteria inhibition with synergy or partial synergy activity. Thus, a strong bactericidal effect of the drug combinations was observed. In vitro data thus suggested that nalidixic acid combined with methyl gallate and carvacrol may be microbiologically beneficial, rather than antagonists.
Comparison and Analysis of Trisector Cell using Antenna Beam- width for CDMA Cellular Mobile Communication Systems
Noh Sun,Choi Dong
IETE Technical Review , 2010,
Abstract: The cell sectorization techniques are widely used in cellular systems to reduce co-channel interference by means of directional antennas. Cell sectorization and improvement of the chip energy/others -interference ratio (Ec /Io ) are technologies to offer good quality of services (QoSs) and coverage for new and -sophisticated power control to achieve high capacity. In this study, we analyze and compare performances of two -trisector cell architectures with different antenna beam-widths-a wide-beam trisector cell (WBTC) and a -narrow-beam trisector cell (NBTC)-in order to achieve effective cell sectoring in CDMA and cellular -mobile -communication systems. These architectures are outcomes of cell sectorization, which is widely employed in cellular -systems for reducing co-channel interference. We verify the effectiveness and validity of the NBTC -architecture by theoretically comparing it with the WBTC architecture (using parameters such as softer -handoff and -interference ratio). Further, we analyze results of a simulation of the WBTC and NBTC and of a field -measurement performed in Namwon city in Korea. From the analysis, we find that the NBTC -architecture is more efficient than the WBTC architecture in minimizing interference from adjacent BSs and increasing cell coverage while maintaining a good QoS.
Identification of DNA methylation changes associated with human gastric cancer
Jung-Hoon Park, Jinah Park, Jung Kyoon Choi, Jaemyun Lyu, Min-Gyun Bae, Young-Gun Lee, Jae-Bum Bae, Dong Yoon Park, Han-Kwang Yang, Tae-You Kim, Young-Joon Kim
BMC Medical Genomics , 2011, DOI: 10.1186/1755-8794-4-82
Abstract: We profiled the methylome of human gastric cancer tissue at 50-bp resolution using a methylated DNA enrichment technique (methylated CpG island recovery assay) in combination with a genome analyzer and a new normalization algorithm.We were able to gain a comprehensive view of promoters with various CpG densities, including CpG Islands (CGIs), transcript bodies, and various repeat classes. We found that gastric cancer was associated with hypermethylation of 5' CGIs and the 5'-end of coding exons as well as hypomethylation of repeat elements, such as short interspersed nuclear elements and the composite element SVA. Hypermethylation of 5' CGIs was significantly correlated with downregulation of associated genes, such as those in the HOX and histone gene families. We also discovered long-range epigenetic silencing (LRES) regions in gastric cancer tissue and identified several hypermethylated genes (MDM2, DYRK2, and LYZ) within these regions. The methylation status of CGIs and gene annotation elements in metastatic lymph nodes was intermediate between normal and cancerous tissue, indicating that methylation of specific genes is gradually increased in cancerous tissue.Our findings will provide valuable data for future analysis of CpG methylation patterns, useful markers for the diagnosis of stomach cancer, as well as a new analysis method for clinical epigenomics investigations.Gastric cancer is the second leading cause of cancer deaths worldwide after lung cancer, resulting in more than 800,000 deaths worldwide every year [1]. The current 5-year survival rate of individuals diagnosed with gastric cancer is only 20-30%, with this low rate being attributable to the fact that most cases are already in an advanced stage when diagnosed. As in all cancers, early detection remains the most promising approach for improving the survival rate. Hence, understanding the cause of tumorigenesis in human gastric tissue is essential.Infection with H. pylori is a well-established and co
Development of an Aggregate Air Quality Index Using a PCA-Based Method: A Case Study of the US Transportation Sector  [PDF]
Jaesung Choi, Yong Shin Park, Ju Dong Park
American Journal of Industrial and Business Management (AJIBM) , 2015, DOI: 10.4236/ajibm.2015.52007
Abstract: For the past couple of decades, the transportation sector has made efforts to preserve and improve air quality for public health and sustainable growth between current and future generations. An easily understandable tool to measure the level of air pollution in the transportation sector by considering multiple air pollutants together might raise awareness about clean air to the public, practitioners, state policy planners, and the government. For this reason, this study develops an aggregate air quality index to help prepare decision makers, which could rank a state according to the different levels of multiple air pollutants. The index is developed for use with principal com-ponent analysis and an algebra about a line segment, and then applied to the US transportation sector using data on five air pollutants (CO, NOx, PM, SO2, and VOCs) in 2008. This study finds that some states were less polluted or more polluted in terms of the index, although their GDP levels for a transport mode were similar to each other. Thus, this finding implies that the necessary actions for stricter air quality standards must be taken in their boundaries.
In Vitro and In Vivo Antibacterial Activity of Punica granatum Peel Ethanol Extract against Salmonella
Jang-Gi Choi,Ok-Hwa Kang,Young-Seob Lee,Hee-Sung Chae,You-Chang Oh,Obiang-Obounou Brice,Min-San Kim,Dong-Hwan Sohn,Hun-Soo Kim,Hyun Park,Dong-Won Shin,Jung-Rae Rho,Dong-Yeul Kwon
Evidence-Based Complementary and Alternative Medicine , 2011, DOI: 10.1093/ecam/nep105
Abstract: Punica granatum is commonly used in Korea as a traditional medicine for the treatment of pathogenic bacteria. In this study, we investigated the in vitro and in vivo antimicrobial activity of P. granatum peel EtOH extract (PGPE) against 16 strains of Salmonella. The minimal inhibitory concentrations of PGPE were in the range of 62.5–1000 x03BCg mL-1. In addition, the in vivo antibacterial activity of the PGPE extract was examined in a S. typhimurium infection mouse model. Mice were initially infected with S. typhimurium and then with PGPE. The extract was found to have significant effects on mortality and the numbers of viable S. typhimurium recovered from feces. Although clinical signs and histological damage were rarely observed in the treated mice, the untreated controls showed signs of lethargy and histological damage in the liver and spleen. Taken together, the results of this study indicate that PGPE has the potential to provide an effective treatment for salmonellosis.
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