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Search Results: 1 - 10 of 6528 matches for " Sang Hyuk Cho "
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Neutron Irradiation of Electronic Materials at HANARO  [PDF]
Kee-Nam Choo, Man-Soon Cho, Byung-Hyuk Jun, Chan-Joong Kim, Sang-Jun Park
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.29093

HANARO, a 30 MW open-pool type multipurpose research reactor, has been operated as a platform for nuclear researches in Korea, and irradiation facilities have been mainly utilized for various nuclear material irradiation tests requested by users. Although most irradiation tests have been related to national R&D relevant to nuclear power, demand for neutron irradiation of electro-magnetic materials is increasing rapidly at HANARO. Another research reactor, which is named the KIJANG research reactor (KJRR), is under construction in Korea. KJRR is dedicated to increasing the national radio-isotopes supply capacity and to the irradiation facilities including Neutron Transmutation Doping (NTD) facilities for power semiconductor production in a large scale and fast neutron irradiation (FNI) facility for fast neutron irradiation. The NTD and FNI facilities in the KJRR reactor can be effectively utilized on the study of separated effect of thermal and fast neutron irradiations on the properties of electro-magnetic materials. HANARO will also specialize more on irradiation research, including neutron irradiation of electronic materials. The research status and possibility of new electro-magnetic materials using neutron irradiation at HANARO are surveyed to ascertain the utilization of neutron irradiation technology in electro-magnetic material researches.

Large cavernous hemangioma in the cecum treated by laparoscopic ileocecal resection
Jung Wook Huh, Sang Hyuk Cho, Jae Hyuk Lee, Hyeong Rok Kim
World Journal of Gastroenterology , 2009,
Abstract: A cavernous hemangioma of the cecum is a rare vascular malformation but is clinically important because of the possibility of massive bleeding. We report a case of a large cavernous hemangioma with pericolic infiltration in the cecum which was removed successfully using minimally invasive surgery.
Ethyl pyruvate attenuates formalin-induced inflammatory nociception by inhibiting neuronal ERK phosphorylation
Min Jung Lee, Minhee Jang, Hyuk-Sang Jung, Sung-Hoon Kim, Ik-Hyun Cho
Molecular Pain , 2012, DOI: 10.1186/1744-8069-8-40
Abstract: EP significantly decreased formalin-induced nociceptive behavior during phase II, the magnitude of paw edema, and the activation of c-Fos in L4-L5 spinal dorsal horn. EP also attenuated the phosphorylation of extracellular signal-regulated kinase (ERK) in the neurons of L4-L5 spinal dorsal horn after formalin injection. Interestingly, the i.t. administration of PD98059, an ERK upstream kinase (MEK) inhibitor, completely blocked the formalin-induced inflammatory nociceptive responses.These results demonstrate that EP may effectively inhibit formalin-induced inflammatory nociception via the inhibition of neuronal ERK phosphorylation in the spinal dorsal horn, indicating its therapeutic potential in suppressing acute inflammatory pain.
Minocycline markedly reduces acute visceral nociception via inhibiting neuronal ERK phosphorylation
Ik-Hyun Cho, Min Jung Lee, Minhee Jang, Nam Gil Gwak, Ka Yeon Lee, Hyuk-Sang Jung
Molecular Pain , 2012, DOI: 10.1186/1744-8069-8-13
Abstract: Minocycline (4, 10, or 40 mg/kg) significantly decreased acetic acid-induced nociception (0-60 minutes post-injection) and the enhancement in the number of c-Fos positive cells in the T5-L2 spinal cord induced by acetic acid injection. Also, the expression of spinal phosphorylated extracellular signal-regulated kinase (p-ERK) induced by acetic acid was reduced by minocycline pre-administration. Interestingly, intrathecal introduction of PD98059, an ERK upstream kinase inhibitor, markedly blocked the acetic acid-stimulated pain responses.These results demonstrate that minocycline effectively inhibits acetic acid-induced acute abdominal nociception via the inhibition of neuronal p-ERK expression in the spinal cord, and that minocycline may have therapeutic potential in suppressing acute abdominal pain.Minocycline is a second-generation tetracycline antibiotic derivative that effectively crosses the blood-brain barrier [1], and which has a proven safety record in humans [2]. Minocycline has anti-inflammatory and neuroprotective effects in animal models of cerebral ischaemia [3,4], traumatic injury [5], glutamate-induced neurotoxicity [6], experimental autoimmune encephalonmyelitis [7], Huntington's disease [8] and Parkinson's disease [2,9,10]. Minocycline's efficacy has been bolstered by studies showing decreased secondary neuronal damage via the inhibition of microglial activation. Recently, it has been demonstrated that this minocycline-mediated microglial inhibition attenuates the development of pain hypersensitivity by inhibiting proinflammatory cytokine expression in rat models of both neuropathic pain and spinal immune activation by intrathecal human immunodeficiency virus-1 (HIV-1) gp120 [11,12]. Also, minocycline completely reverses mechanical hyperalgesia in diabetic rats through microglia-induced changes in the expression of the potassium chloride co-transporter 2 (KCC2) in the spinal cord [13]. In addition, we confirmed that minocycline attenuates tactile hy
Phenotypic Characterization of Peripheral T Cells and Their Dynamics in Scrub Typhus Patients
Bon-A Cho,Youngho Ko,Yeon-Sook Kim,Sanguk Kim,Myung-Sik Choi,Ik-Sang Kim,Hang-Rae Kim ,Nam-Hyuk Cho
PLOS Neglected Tropical Diseases , 2012, DOI: 10.1371/journal.pntd.0001789
Abstract: Background Scrub typhus, caused by Orientia tsutsugamushi infection, is one of the main causes of febrile illness in the Asia-Pacific region. Although cell-mediated immunity plays an important role in protection, little is known about the phenotypic changes and dynamics of leukocytes in scrub typhus patients. Methodology/Principal Findings To reveal the underlying mechanisms of immunological pathogenesis, we extensively analyzed peripheral blood leukocytes, especially T cells, during acute and convalescent phases of infection in human patients and compared with healthy volunteers. We observed neutrophilia and CD4+ T lymphopenia in the acute phase of infection, followed by proliferation of CD8+ T cells during the convalescent phase. Massive T cell apoptosis was detected in the acute phase and preferential increase of CD8+ T cells with activated phenotypes was observed in both acute and convalescent phases, which might be associated or correlated with elevated serum IL-7 and IL-15. Interestingly, peripheral Treg cells were significantly down-regulated throughout the disease course. Conclusions/Significance The remarkable decrease of CD4+ T cells, including Treg cells, during the acute phase of infection may contribute to the loss of immunological memory that are often observed in vaccine studies and recurrent human infection.
Bacterial Heavy Metal Resistance Genes and Bioremediation Potential  [PDF]
Hannah Johnson, Hyuk Cho, Madhusudan Choudhary
Computational Molecular Bioscience (CMB) , 2019, DOI: 10.4236/cmb.2019.91001
Abstract: There is a worldwide distribution of heavy metal pollution that can be managed with a bioremediation approach using microorganisms. Several bacterial species belonging to the Proteobacteria have been shown to tolerate heavy metal stress, including toxic salts of noblemetals. Rhodobacter sphaeroides, a model bacterium has previously been utilized for bioremediation studies. A bioinformatics approach was employed here to identify the distribution of genes associated with heavy metal tolerance among the sequenced bacterial genomes currently available on the NCBI database. The distribution of these genes among different groups of bacteria and the Cluster of Orthologous Groups (COGs) were further characterized. A total of 170,000 heavy metal related genes were identified across all bacterial species, with a majority of the genes found in Proteobacteria (46%) and Terrabacteria (39%). Analysis of COGs revealed that the majority of heavy metal related genes belong to metabolism (COG 3), including ionic transport, amino acid biosynthesis, and energy production.
Genome-Based Construction of the Metabolic Pathways of Orientia tsutsugamushi and Comparative Analysis within the Rickettsiales Order
Chan-Ki Min,Jae-Seong Yang,Sanguk Kim,Myung-Sik Choi,Ik-Sang Kim,Nam-Hyuk Cho
Comparative and Functional Genomics , 2008, DOI: 10.1155/2008/623145
Abstract: Orientia tsutsugamushi, the causative agent of scrub typhus, is an obligate intracellular bacterium that belongs to the order of Rickettsiales. Recently, we have reported that O. tsutsugamushi has a unique genomic structure, consisting of highly repetitive sequences, and suggested that it may provide valuable insight into the evolution of intracellular bacteria. Here, we have used genomic information to construct the major metabolic pathways of O. tsutsugamushi and performed a comparative analysis of the metabolic genes and pathways of O. tsutsugamushi with other members of the Rickettsiales order. While O. tsutsugamushi has the largest genome among the members of this order, mainly due to the presence of repeated sequences, its metabolic pathways have been highly streamlined. Overall, the metabolic pathways of O. tsutsugamushi were similar to Rickettsia but there were notable differences in several pathways including carbohydrate metabolism, the TCA cycle, and the synthesis of cell wall components as well as in the transport systems. Our results will provide a useful guide to the postgenomic analysis of O. tsutsugamushi and lead to a better understanding of the virulence and physiology of this intracellular pathogen.
The analytic continuation of hyperbolic space
Yunhi Cho,Hyuk Kim
Mathematics , 2006,
Abstract: We define and study an extended hyperbolic space which contains the hyperbolic space and de Sitter space as subspaces and which is obtained as an analytic continuation of the hyperbolic space. The construction of the extended space gives rise to a complex valued geometry consistent with both the hyperbolic and de Sitter space. Such a construction shed a light and inspires a new insight for the study of the hyperbolic geometry and Lorentzian geometry. We discuss the advantages of this new geometric model as well as some of its applications.
Volume of $C^{1,α}$-boundary domain in extended hyperbolic space
Yunhi Cho,Hyuk Kim
Mathematics , 2006,
Abstract: We consider the projectivization of Minkowski space with the analytic continuation of the hyperbolic metric and call this an extended hyperbolic space. We can measure the volume of a domain lying across the boundary of the hyperbolic space using an analytic continuation argument. In this paper we show this method can be further generalized to find the volume of a domain with smooth boundary with suitable regularity in dimension 2 and 3. We also discuss that this volume is invariant under the group of hyperbolic isometries and that this regularity condition is sharp.
Absolute frequency measurement of 1S0 (F = 1/2) - 3P0 (F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS
Chang Yong Park,Dai-Hyuk Yu,Won-Kyu Lee,Sang Eon Park,Eok Bong Kim,Sun Kyung Lee,Jun Woo Cho,Tai Hyun Yoon,Jongchul Mun,Sung Jong Park,Taeg Yong Kwon,Sang-Bum Lee
Physics , 2011,
Abstract: We measured the absolute frequency of the optical clock transition 1S0 (F = 1/2) - 3P0 (F = 1/2) of 171Yb atoms confined in a one-dimensional optical lattice and it was determined to be 518 295 836 590 863.5(8.1) Hz. The frequency was measured against Terrestrial Time (TT; the SI second on the geoid) by using an optical frequency comb of which the frequency was phase-locked to an H-maser as a flywheel oscillator traceable to TT. The magic wavelength was also measured as 394 798.48(79) GHz. The results are in good agreement with two previous measurements of other institutes within the specified uncertainty of this work.
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