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Search Results: 1 - 10 of 45149 matches for " Dong-Gun Kim "
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Energy Harvesting Strategy Using Piezoelectric Element Driven by Vibration Method  [PDF]
Dong-Gun Kim, So-Nam Yun, Young-Bog Ham, Jung-Ho Park
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.22014
Abstract: This study demonstrates a method for harvesting the electrical power by the piezoelectric actuator from vibration energy. This paper presents the energy harvesting technique using the piezoelectric element of a bimorph type driven by a geared motor and a vibrator. The geared motor is a type of PWM controlled device that is a combination of an oval shape cam with five gears and a speed controller. When using the geared motor, the piezoelectric element is size of 36L×13W×0.6H. The output voltage characteristics of the piezoelectric element were investigated in terms of the displacement and vibration. When using the vibrator, the electric power harvesting is based on piezoelectric effect and piezoelectric vibrator consists of a magnetic type oscillator, a cantilever, a bimorph actuator and controllers. Low frequency operating technique using piezoelectric vibrator is very important because normal vibration sources in the environment such as building, human body, windmill and ship have low frequency characteristics. We can know from this study results that there are many energy sources such as vibration, wind power and wave power. Also, these can be used to the energy harvesting system using smart device like piezoelectric element.
Regularity for Solutions of Second-Order Nonlinear Integrodifferential Functional Equations
Park Dong-Gun,Jeong Jin-Mun,Kim Han-Geul
Journal of Inequalities and Applications , 2010,
Abstract: We deal with the well-posedness for solutions of nonlinear integrodifferential equations of second-order in Hilbert spaces by converting the problem into the contraction mapping principle with more general conditions on the principal operators and the nonlinear terms and obtain a variation of constant formula of solutions of the given nonlinear equations.
Regularity for Solutions of Second-Order Nonlinear Integrodifferential Functional Equations
Dong-Gun Park,Jin-Mun Jeong,Han-Geul Kim
Journal of Inequalities and Applications , 2010, DOI: 10.1155/2010/280463
Abstract: We deal with the well-posedness for solutions of nonlinear integrodifferential equations of second-order in Hilbert spaces by converting the problem into the contraction mapping principle with more general conditions on the principal operators and the nonlinear terms and obtain a variation of constant formula of solutions of the given nonlinear equations.
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.
Molecular epidemiology of extended-spectrum β-lactamase-producing Escherichia coli in the community and hospital in Korea: emergence of ST131 producing CTX-M-15
Sun Hee Park, Ji-Hyun Byun, Su-Mi Choi, Dong-Gun Lee, Si-Hyun Kim, Jae-Cheol Kwon, Chulmin Park, Jung-Hyun Choi, Jin-Hong Yoo
BMC Infectious Diseases , 2012, DOI: 10.1186/1471-2334-12-149
Abstract: A total of 142 ESBL-producing E. coli isolates were collected at Daejeon St Mary’s Hospital in Korea from January 2008 to September 2009. The ESBLs were characterized by PCR sequencing using specific primers. The genetic relatedness was determined by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).Of 142 isolates, 139 were positive for CTX-M type ESBLs; CTX-M-14 (n?=?69, 49.6?%), CTX-M-15 (n?=?53, 38.1?%) and both CTX-M-14 and -15 (n?=?17, 12.2?%). CTX-M-14 and CTX-M-15 were detected in both community and hospital isolates whereas isolates producing both CTX-M14 and-15 were mainly identified in the hospital. CTX-M producing E. coli isolates were genetically heterogeneous, revealing 75 distinct PFGE types. By MLST, 21 distinctive STs including 5 major STs (ST131, ST405, ST38, ST10, and ST648) were identified. Major STs were distributed in both community and hospital isolates, and ST131 was the predominant clone regardless of the locations of acquisition. No specific major STs were confined to a single type of ESBLs. However, ST131 clones were significantly associated with CTX-M-15 and the majority of them were multidrug-resistant. Distinctively, we identified a hospital epidemic caused by the dissemination of an epidemic strain, ST131-PFGE type 10, characterized by multidrug resistance and co-producing both CTX-Ms with OXA-1 or TEM-1b.The epidemiology of ESBL-producing E. coli is a complex and evolving phenomenon attributed to the horizontal transfer of genetic elements and clonal spread of major clones, predominantly ST131. The multidrug resistant ST131 clone producing CTX-M-15 has emerged as a major clone in both the community and hospital, suggesting the widespread of this epidemic clone in Korea.
Regularity of Parabolic Hemivariational Inequalities with Boundary Conditions
Park Dong-Gun,Jeong Jin-Mun,Park SunHye
Journal of Inequalities and Applications , 2009,
Abstract: We prove the regularity for solutions of parabolic hemivariational inequalities of dynamic elasticity in the strong sense and investigate the continuity of the solution mapping from initial data and forcing term to trajectories.
Investigation of electron beam induced migration of hydrogen in Mg-doped GaN using Eu as a probe
Brandon Mitchell,Donghwa Lee,Dong-gun Lee,Atsushi Koizumi,Yasufumi Fujiwara,Volkmar Dierolf
Physics , 2013, DOI: 10.1103/PhysRevB.88.121202
Abstract: We demonstrate the use of hydrogen induced changes in the emission of isoelectric Eu ions, in Mg-doped p-type GaN, as a powerful probe to study the dynamics of hydrogen movement under electron beam irradiation. We identify, experimentally, a two-step process in the dissociation of Mg-H complexes and propose, based on density functional theory, that the presence of minority carriers and resulting charge states of the hydrogen drives this process.
Conceptual Modeling of Contaminated Solute Transport Based on Stream Tube Model  [PDF]
Seung-Gun Chung, Soon-Jae Lee, Dong-Ju Kim, Sang-Hyup Lee, Jae-Woo Choi
Advances in Chemical Engineering and Science (ACES) , 2012, DOI: 10.4236/aces.2012.24059
Abstract: In this study, we performed a conceptual modeling on solute transport based on theoretical stream tube model (STM) with various travel time distributions assuming a pure convective flow through each tube in order to investigate how the lengths and distributions of solute travel time through STM affect the breakthrough curves at the end mixing surface. The conceptual modeling revealed that 1) the shape of breakthrough curve (BTC) at the mixing surface was determined by not only input travel time distributions but also solute injection mode such as sampling time and pulse lengths; 2) the increase of pulse length resulted in the linear increase of the first time moment (mean travel time) and quadratic increase of the second time moment (variance of travel time) leading to more spreading of solute, however, the second time moment was not affected by travel time distributions and 3) for a given input distributions the increase in travel distance resulted in more dispersion with the quadratic increase of travel time variance. This indicates that stream tube model obeying strictly pure convective flow follows the concept of convective-lognormal transport (CLT) model regardless the input travel time distributions.
CD24 cross-linking induces apoptosis in, and inhibits migration of, MCF-7 breast cancer cells
Jong Kim, Eunyoung Ko, Wonshik Han, Jeong Lee, Kyung-Min Lee, Incheol Shin, Sangmin Kim, Jong Lee, Jihyoung Cho, Ji-Yeon Bae, Hyeon-Gun Jee, Dong-Young Noh
BMC Cancer , 2008, DOI: 10.1186/1471-2407-8-118
Abstract: MCF-7 and MDA-MB-231 cells were treated with anti-rabbit polyclonal IgG or anti-human CD24 rabbit polyclonal antibodies to induce cross-linking, and then growth was studied. Changes in cell characteristics such as cell cycle modulation, cell death, survival in three-dimensional cultures, adhesion, and migration ability were assayed after CD24 cross-linking in MCF-7.Expression of CD24 was analyzed by flow cytometry in MDA-MB-231 and MCF-7 cells where 2% and 66% expression frequencies were observed, respectively. CD24 cross-linking resulted in time-dependent proliferation reduction in MCF-7 cells, but no reduction in MDA-MB-231 cells. MCF-7 cell survival was reduced by 15% in three-dimensional culture after CD24 cross-linking. Increased MCF-7 cell apoptosis was observed after CD24 cross-linking, but no cell cycle arrest was observed in that condition. The migration capacity of MCF-7 cells was diminished by 30% after CD24 cross-linking.Our results showed that CD24 cross-linking induced apoptosis and inhibited migration in MCF-7 breast cancer cells. We conclude that CD24 may be considered as a novel therapeutic target for breast cancer.CD24 is expressed in hematopoietic cell types, including B-cell precursors and neutrophils [1], and is also conventionally used as a differentiation marker for keratinocytes [2]. Accumulating evidence supports a role for CD24 in a variety of malignancies, including B-cell lymphoma, renal cell carcinoma, small-cell and non small-cell lung carcinoma, nasopharyngeal carcinoma, hepatocellular carcinoma, bladder carcinoma, epithelial ovarian cancer and breast cancer [3].CD24, designated 'heat-stable antigen' (HSA) in mice, is a glycosylated cell-surface protein linked to the membrane via a glycosyl-phosphatidylinositol (GPI) anchor [4]. CD24 has several potential N- and O-linked glycosylation sites, which act as ligands for P-selectin [4].CD24 is involved in cellular adhesion processes and signalling pathways in cancer cells that are dependent
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
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