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Search Results: 1 - 10 of 4653 matches for " Kwang-Youn Cho "
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Synthesis of Carbon Nanomaterials-CdSe Composites and Their Photocatalytic Activity for Degradation of Methylene Blue
Ming-Liang Chen,Ze-Da Meng,Lei Zhu,Chong-Yeon Park,Jong-Geun Choi,Trisha Ghosh,Kwang-Youn Cho,Won-Chun Oh
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/964872
Abstract: We use multi-walled carbon nanotube (MWCNT) and graphene as carbon nanomaterials to obtain carbon nanomaterilas-CdSe composites using a facile hydrothermal method. The intrinsic characteristics of resulting composites were studied by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectrophotometer. The as-prepared carbon nanomaterilas-CdSe composites possessed great adsorptivity of dyes, extended light absorption range, and efficient charge separation properties simultaneously. Hence, in the photodegradation of methylene blue, a significant enhancement in the reaction rate was observed with carbon nanomaterilas-CdSe composites, compared to the CdSe compound.
A Rapid Murine Coma and Behavior Scale for Quantitative Assessment of Murine Cerebral Malaria
Ryan W. Carroll,Mark S. Wainwright,Kwang-Youn Kim,Trilokesh Kidambi,Noé D. Gómez,Terrie Taylor,Kasturi Haldar
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0013124
Abstract: Cerebral malaria (CM) is a neurological syndrome that includes coma and seizures following malaria parasite infection. The pathophysiology is not fully understood and cannot be accounted for by infection alone: patients still succumb to CM, even if the underlying parasite infection has resolved. To that effect, there is no known adjuvant therapy for CM. Current murine CM (MCM) models do not allow for rapid clinical identification of affected animals following infection. An animal model that more closely mimics the clinical features of human CM would be helpful in elucidating potential mechanisms of disease pathogenesis and evaluating new adjuvant therapies.
Modifiedhydrothermalsynthesisandcharacterizationofreducedgrapheneoxide-silverselenidenanocompositeswithenhancedreactiveoxygenspeciesgeneration
Lei Zhu,Shu Ye,Asghar Ali,Kefayat Ulla,Kwang Youn Cho,Won-Chun Oh
催化学报 , 2015, DOI: 10.1016/S1872-2067(14)60275-8
Abstract: ?Avisible-lightphotocatalystcontainingAg2Seandreducedgrapheneoxide(RGO)wassynthesizedbyafacilesonochemical-assistedhydrothermalmethod.X-raydiffraction,scanningelectronmicroscopywithenergy-dispersiveX-rayanalysis,andultraviolet-visiblediffusereflectancespectroscopyresultsindicatedthattheRGO-Ag2SenanocompositecontainedsmallcrystallineAg2Senanoparticlesdispersedovergraphenenanosheetsandabsorbedvisiblelight.Thehighcrystallinityofthenanoparticlesincreasedphotocatalyticactivitybyfacilitatingchargetransport.N2adsorption-desorptionmeasurementsrevealedthattheRGO-Ag2Senanocompositecontainednumerousporeswithanaveragediameterof9nm,whichshouldallowreactantmoleculestoreadilyaccesstheAg2Senanoparticles.TheRGO-Ag2SenanocompositeexhibitedhigherphotocatalyticactivitythanbulkAg2SenanoparticlestodegradeorganicpollutantrhodamineBandindustrialdyeTexbriteBA-Lundervisible-lightirradiation(λ>420nm).ThegenerationofreactiveoxygenspeciesinRGO-Ag2Sewasevaluatedthroughitsabilitytooxidize1,5-diphenylcarbazideto1,5-diphenylcarbazone.ThesmallsizeoftheAg2SenanoparticlesinRGO-Ag2Sewasrelatedtotheuseofultrasonicationduringtheirformation,revealingthatthisapproachisattractivetoformporousRGO-Ag2Sematerialswithhighphotocatalyticactivityundervisiblelight.
A Novel Herbal Medicine KIOM-MA Exerts an Anti-Inflammatory Effect in LPS-Stimulated RAW 264.7 Macrophage Cells
You-Chang Oh,Won-Kyung Cho,Yun Hee Jeong,Ga Young Im,Aeyung Kim,Youn-Hwan Hwang,Taesoo Kim,Kwang Hoon Song,Jin Yeul Ma
Evidence-Based Complementary and Alternative Medicine , 2012, DOI: 10.1155/2012/462383
Abstract: KIOM-MA was recently reported as a novel herbal medicine effective for atopic dermatitis and asthma. In this study, we have demonstrated the inhibitory effect of KIOM-MA on proinflammatory mediator produced in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. KIOM-MA significantly inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) as well as nitric oxide (NO) and prostaglandin E2 (PGE2). Consistent with the inhibitory effect on PGE2, KIOM-MA suppresses the LPS-induced migration of macrophages and gelatinase activity and the expression of matrix metalloprotease-9 (MMP-9) in a dose-dependent manner. Additionally, KIOM-MA showed a strong suppressive effect on the inflammatory cytokines production such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). We also found that KIOM-MA inhibits the activation of nuclear factor-κB (NF-κB) and represses the activity of extracellular signal-regulated kinase (ERK), p38, and c-Jun NH2-terminal kinase (JNK) mitogen-activated protein kinases (MAPKs). Taken together, we elucidated the mechanism of anti-inflammatory effect of KIOM-MA using RAW 264.7 cells stimulated by LPS.
In Vitro and In Vivo Genotoxicity Assessment of Aristolochia manshuriensis Kom.
Youn-Hwan Hwang,Taesoo Kim,Won-Kyung Cho,Hye Jin Yang,Dong Hoon Kwak,Hyunil Ha,Kwang Hoon Song,Jin Yeul Ma
Evidence-Based Complementary and Alternative Medicine , 2012, DOI: 10.1155/2012/412736
Abstract: Arisolochiae species plants containing aristolochic acids I and II (AA I and AA II) are well known to cause aristolochic acid nephropathy (AAN). Recently, there are various approaches to use AAs-containing herbs after the removal of their toxic factors. However, there is little information about genotoxicity of Arisolochiae manshuriensis Kom. (AMK) per se. To obtain safety information for AMK, its genotoxicity was evaluated in accordance with OECD guideline. To evaluate genotoxicity of AMK, we tested bacterial reverse mutation assay, chromosomal aberration test, and micronucleus test. Here, we also determined the amounts of AA I and II in AMK (2.85 ± 0.08 and 0.50 ± 0.02 mg/g extract, resp.). In bacterial reverse mutation assay, AMK dose-dependently increased revertant colony numbers in TA98, TA100 and TA1537 regardless of metabolic activation. AMK increased the incidence of chromosomal aberration in Chinese hamster ovary-K1 cells, but there was no statistically significant difference. The incidences of micronucleus in bone marrow erythrocyte were significantly increased in mice after oral administration of AMK (5000 mg/kg), comparing with those of vehicle group (<0.05). The results of three standard tests suggest that the genotoxicity of AMK is directly related to the AAs contents in AMK.
Characteristics and Prognostic Implications of High-Risk HPV-Associated Hypopharyngeal Cancers
Young-Hoon Joo, Youn-Soo Lee, Kwang-Jae Cho, Jun-Ook Park, In-Chul Nam, Chung-Soo Kim, Sang-Yeon Kim, Min-Sik Kim
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0078718
Abstract: Background High-risk human papillomavirus (HPV) is an oncogenic virus that causes oropharyngeal cancers, and it has a favorable outcome after the treatment. Unlike in oropharyngeal cancer, the prevalence and role of high-risk HPV in the etiology of hypopharyngeal squamous cell carcinoma (HPSCC) is uncertain. Objective The aim of the present study was to evaluate the effect and prognostic significance of high-risk HPV in patients with HPSCC. Methods The study included 64 subjects with HPSCC who underwent radical surgery with or without radiation-based adjuvant therapy. Primary tumor sites were the pyriform sinus in 42 patients, posterior pharyngeal wall in 19 patients, and postcricoid area in 3 patients. High-risk HPV in situ hybridization was performed to detect HPV infection. Results The positive rate of high-risk HPV in situ hybridization was 10.9% (7/64). There was a significant difference in the fraction of positive high-risk HPV among pyriform sinus cancer (16.7%), posterior pharyngeal wall cancer (0%), and postcricoid area cancer (0%) (p = 0.042). The laryngoscopic examination revealed a granulomatous and exophytic appearance in 85.7% (6/7) of patients with high-risk HPV-positive pyriform sinus cancer, but in only 31.4% (11/35) of patients with high-risk HPV-negative pyriform sinus cancer (p = 0.012). Significant correlations were found between positive high-risk HPV and younger age (p = 0.050) and non-smoking status (p = 0.017). HPV-positive patients had a significantly better disease-free survival (p = 0.026) and disease-specific survival (p = 0.047) than HPV-negative patients. Conclusions High-risk HPV infection is significantly related to pyriform sinus cancer in patients with HPSCC.
Optimal Operation of Energy Storage Using Linear Programming Technique
Luis T. Youn,Sohyung Cho
Lecture Notes in Engineering and Computer Science , 2009,
Abstract:
Deep-submicron Placement Minimizing Crosstalk
Jun Dong Cho,Jin Youn Cho
VLSI Design , 2001, DOI: 10.1155/2001/46394
Abstract: Placement of multiple dies on an MCM or high-performance VLSI substrate is a nontrivial task in which multiple criteria need to be considered simultaneously to obtain a true multi-objective optimization. Unfortunately, the exact physical attributes of a design are not known in the placement step until the entire design process is carried out. When the performance issues are considered, crosstalk noise constraints in the form of net separation and via constraint become important. In this paper, for better performance and wirability estimation during placement for MCMs, several performance constraints are taken into account simultaneously. A graph-based wirability estimation along with the Genetic placement optimization technique is proposed to minimize crosstalk, crossings, wirelength and the number of layers. Our work is significant since it is the first attempt at bringing the crosstalk and other performance issues into the placement domain.
Air Traffic Volume and Air Traffic Control Human Errors  [PDF]
Woo-Choon Moon, Kwang-Eui Yoo, Youn-Chul Choi
Journal of Transportation Technologies (JTTs) , 2011, DOI: 10.4236/jtts.2011.13007
Abstract: Navigable airspaces are becoming more crowded with increasing air traffic, and the number of accidents caused by human errors is increasing. The main objective of this paper is to evaluate the relationship between air traffic volume and human error in air traffic control (ATC). First, the paper identifies categories and elements of ATC human error through a review of existing literature, and a study through interviews and surveys of ATC safety experts. And then the paper presents the results of an experiment conducted on 52 air traffic controllers sampled from the Korean ATC organization to find out if there is any relationship between traffic volume and air traffic controller human errors. An analysis of the experiment clearly showed that several types of ATC human error are influenced by traffic volume. We hope that the paper will make its contribution to aviation safety by providing a realistic basis for securing proper manpower and facility in accordance with the level of air traffic volume.
Carbon nanotube, graphene, nanowire, and molecule-based electron and spin transport phenomena using the non-equilibrium Green function method at the level of first principles theory
Woo Youn Kim,Kwang S. Kim
Physics , 2007, DOI: 10.1002/jcc.20865
Abstract: Based on density functional theory (DFT), we have developed algorithms and a program code to investigate the electron transport characteristics for a variety of nanometer scaled devices in the presence of an external bias voltage. We employed basis sets comprised of linear combinations of numerical type atomic orbitals and k-point sampling for the realistic modeling of the bulk electrode. The scheme coupled with the matrix version of the non-equilibrium Green function method enables determination of the transmission coefficients at a given energy and voltage in a self-consistent manner, as well as the corresponding current-voltage (I-V) characteristics. This scheme has advantages because it is applicable to large systems, easily transportable to different types of quantum chemistry packages, and extendable to describe time-dependent phenomena or inelastic scatterings. It has been applied to diverse types of practical electronic devices such as carbon nanotubes, graphene nano-ribbons, metallic nanowires, and molecular electronic devices. The quantum conductance phenomena for systems involving quantum point contacts and I-V curves are described for the dithiol-benzene molecule in contact with two Au electrodes using the k-point sampling method.
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