Soon Kwon

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Papers by Soon Kwon

Association between serum vitamin D and depressive symptoms among female workers in the manufacturing industry

Annals of occupational and environmental medicine, 2015

Vitamin D has been known to maintain the body's balance of calcium and phosphorus as well as ... more Vitamin D has been known to maintain the body's balance of calcium and phosphorus as well as skeletal health. There has been increasing emphasis on the importance of vitamin D as recent studies have been reporting the specific functions of vitamin D in the cerebral nervous system and the association between the level of serum vitamin D and depressive symptoms. However, there is currently a paucity of research investigating the association between serum vitamin D and depressive symptoms in Korean subjects. Consequently, this study has aimed to determine the level of serum vitamin D and explore the association between serum vitamin D and depressive symptoms in Korean female workers. A medical examination, questionnaire, anthropometric measurements, and a blood test were conducted between February 3 and March 7, 2014 in 1054 subjects among female workers in the manufacturing industry who underwent physical examinations in a university hospital. From this data, we identified the lev...

Parallel Computing Performance of a 3D Cardiac Tissue Model

The Sixth IEEE International Conference on Computer and Information Technology (CIT'06), 2006

We developed a three dimensional cardiac tissue model based on human cardiac cell and mono-domain... more We developed a three dimensional cardiac tissue model based on human cardiac cell and mono-domain approximation for action potential propagation. The human myocyte model proposed by ten Tusscher et al. (TNNP model) (2004) for cell electrophysiology and a mono-domain method for electric wave propagation are used to simulate the cardiac tissue propagation mechanism using a finite element method. To delineate

Highly Durable and Active PtFe Nanocatalyst for Electrochemical Oxygen Reduction Reaction

Journal of the American Chemical Society, 2015

Demand on the practical synthetic approach to the high performance electrocatalyst is rapidly inc... more Demand on the practical synthetic approach to the high performance electrocatalyst is rapidly increasing for fuel cell commercialization. Here we present a synthesis of highly durable and active intermetallic ordered face-centered tetragonal (fct)-PtFe nanoparticles (NPs) coated with a &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;dual purpose&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; N-doped carbon shell. Ordered fct-PtFe NPs with the size of only a few nanometers are obtained by thermal annealing of polydopamine-coated PtFe NPs, and the N-doped carbon shell that is in situ formed from dopamine coating could effectively prevent the coalescence of NPs. This carbon shell also protects the NPs from detachment and agglomeration as well as dissolution throughout the harsh fuel cell operating conditions. By controlling the thickness of the shell below 1 nm, we achieved excellent protection of the NPs as well as high catalytic activity, as the thin carbon shell is highly permeable for the reactant molecules. Our ordered fct-PtFe/C nanocatalyst coated with an N-doped carbon shell shows 11.4 times-higher mass activity and 10.5 times-higher specific activity than commercial Pt/C catalyst. Moreover, we accomplished the long-term stability in membrane electrode assembly (MEA) for 100 h without significant activity loss. From in situ XANES, EDS, and first-principles calculations, we confirmed that an ordered fct-PtFe structure is critical for the long-term stability of our nanocatalyst. This strategy utilizing an N-doped carbon shell for obtaining a small ordered-fct PtFe nanocatalyst as well as protecting the catalyst during fuel cell cycling is expected to open a new simple and effective route for the commercialization of fuel cells.

Atherosclerotic renal artery stenosis: current status

Advances in chronic kidney disease, 2015

Atherosclerotic renal artery stenosis (ARAS) remains a major cause of secondary hypertension and ... more Atherosclerotic renal artery stenosis (ARAS) remains a major cause of secondary hypertension and kidney failure. Randomized prospective trials show that medical treatment should constitute the main therapeutic approach in ARAS. Regardless of intensive treatment and adequate blood pressure control, however, renal and extrarenal complications are not uncommon. Yet, the precise mechanisms, accurate detection, and optimal treatment in ARAS remain elusive. Strategies oriented to early detection and targeting these pathogenic pathways might prevent development of clinical end points. Here, we review the results of recent clinical trials, current understanding of the pathogenic mechanisms, novel imaging techniques to assess kidney damage in ARAS, and treatment options.

Route to the Smallest Doped Semiconductor: Mn 2+ -Doped (CdSe) 13 Clusters

Journal of the American Chemical Society, 2015

Doping semiconductor nanocrystals with magnetic transition-metal ions has attracted fundamental i... more Doping semiconductor nanocrystals with magnetic transition-metal ions has attracted fundamental interest to obtain a nanoscale dilute magnetic semiconductor, which has unique spin exchange interaction between magnetic spin and exciton. So far, the study on the doped semiconductor NCs has usually been conducted with NCs with larger than 2 nm because of synthetic challenges. Herein, we report the synthesis and characterization of Mn(2+)-doped (CdSe)13 clusters, the smallest doped semiconductors. In this study, single-sized doped clusters are produced in large scale. Despite their small size, these clusters have semiconductor band structure instead of that of molecules. Surprisingly, the clusters show multiple excitonic transitions with different magneto-optical activities, which can be attributed to the fine structure splitting. Magneto-optically active states exhibit giant Zeeman splittings up to elevated temperatures (128 K) with large g-factors of 81(±8) at 4 K. Our results present a new synthetic method for doped clusters and facilitate the understanding of doped semiconductor at the boundary of molecules and quantum nanostructure.

Hybrid Cellular Nanosheets for High-Performance Lithium-Ion Battery Anodes

Journal of the American Chemical Society, Jan 10, 2015

We report a simple synthetic method of carbon-based hybrid cellular nanosheets that exhibit outst... more We report a simple synthetic method of carbon-based hybrid cellular nanosheets that exhibit outstanding electrochemical performance for many key aspects of lithium-ion battery electrodes. The nanosheets consist of close-packed cubic cavity cells partitioned by carbon walls, resembling plant leaf tissue. We loaded carbon cellular nanosheets with SnO2 nanoparticles by vapor deposition method and tested the performance of the resulting SnO2-carbon nanosheets as anode materials. The specific capacity is 914 mAh g(-1) on average with a retention of 97.0% during 300 cycles, and the reversible capacity is decreased by only 20% as the current density is increased from 200 to 3000 mA g(-1). In order to explain the excellent electrochemical performance, the hybrid cellular nanosheets were analyzed with cyclic voltammetry, in situ X-ray absorption spectroscopy, and transmission electron microscopy. We found that the high packing density, large interior surface area, and rigid carbon wall netwo...

STAT1 deficiency redirects IFN signalling toward suppression of TLR response through a feedback activation of STAT3

Scientific reports, Jan 24, 2015

Interferons (IFNs) potentiate macrophage activation typically via a STAT1-dependent pathway. Rece... more Interferons (IFNs) potentiate macrophage activation typically via a STAT1-dependent pathway. Recent studies suggest a functioning of STAT1-independent pathway in the regulation of gene expression by IFN-γ, thus pointing to the diversity in cellular responses to IFNs. Many functions of IFNs rely on cross-regulation of the responses to exogenous inflammatory mediators such as TLR ligands. Here we investigated the contribution of STAT1-independent pathway to macrophage activation and its underlying mechanism in the context of combined stimulation of IFN and TLR. We found that TLR-induced production of inflammatory cytokines (TNF-α, IL-12) was not simply nullified but was significantly suppressed by signaling common to IFN-γ and IFN-β in STAT1-null macrophages. Such a shift in the suppression of TLR response correlated with a sustained STAT3 activation and attenuation of NF-κB signaling. Using a JAK2/STAT3 pathway inhibitor or STAT3-specific siRNA, blocking STAT3 in that context restore...

A Perceptual Visual Feature Extraction Method Achieved by Imitating V1 and V4 of the Human Visual System

Cognitive Computation, 2012

ABSTRACT In this paper, we present a new shape encoding method for object recognition. We first i... more ABSTRACT In this paper, we present a new shape encoding method for object recognition. We first introduce a neuro-physiologically inspired visual part detector and shape encoder. The optimal form of the visual part detector is a combination of a circular symmetry detector and a corner-like structure detector. A perceptually novel shape descriptor, known as the curvature-orientation descriptor, is then discussed. This descriptor encodes the curvature as well as the dominant orientation. The perceptual shape encoder enhances the performance of feature matching and object recognition taken from standard test images. The results from the repeatability and object recognition tests validate the feasibility of the proposed perceptual feature extraction method.

Analysis of mobile phone's immunity to electrostatic discharge soft failures

2010 Asia-Pacific International Symposium on Electromagnetic Compatibility, 2010

A technique for the analysis of mobile phone's immunity to the electrostatic discharge (ESD)... more A technique for the analysis of mobile phone's immunity to the electrostatic discharge (ESD) soft failures is proposed. First, a mobile phone, ESD simulator and ESD testing setup are modelled and then the simulation is performed using time-domain full-wave electromagnetic simulator. The proposed technique is applied to the analysis of ESD soft failure of mobile phones and the root causes of the ESD soft failure are investigated. ESD voltages obtained from simulation are compared to that from measurement. Also, improvement in the frequency of occurrence of ESD soft failure by the application of countermeasures derived from ESD simulation result is presented.

Predictive factors of contrast-enhanced ultrasonography for the response to transarterial chemoembolization in hepatocellular carcinoma

Clinical and molecular hepatology, 2015

The predictive role of contrast-enhanced ultrasonography (CEUS) before performing transarterial c... more The predictive role of contrast-enhanced ultrasonography (CEUS) before performing transarterial chemoembolization (TACE) has not been determined. We assessed the possible predictive factors of CEUS for the response to TACE. Seventeen patients with 18 hepatocellular carcinoma (HCC) underwent TACE. All of the tumors were studied with CEUS before TACE using a second-generation ultrasound contrast agent (SonoVue®, Bracco, Milan, Italy). The tumor response to TACE was classified with a score between 1 and 4 according to the remaining enhancing-tumor percentage based on modified response evaluation criteria in solid tumors (mRECIST): 1, enhancing tumor…

<title>On-road obstacle detection and tracking system using robust global stereo vision method</title>

Signal and Data Processing of Small Targets 2010, 2010

In this paper, we present a visual obstacle detection and tracking system based on a dense stereo... more In this paper, we present a visual obstacle detection and tracking system based on a dense stereo vision method. We combine a global stereo matcher with a correlation based cost function for generating a reliable disparity-map. An NCC algorithm is robust to illumination variation, and a BP based global disparity computation algorithm is efficient for recovering the disparity information of a large textureless area in real driving scenes. Then an obstacle detector and a tracker module are implemented and tested under actual driving conditions. Using U-V disparity representation, a road profile is efficiently extracted, and obstacle ROI can be detected. In the process of obstacle detection, a few heuristic constraints are applied to exclude wrong candidates, and a further verification step is proceeded by a tracker. Implemented system offers accurate and reliable range images under various noisy imaging conditions, which results in robust detection and tracking performance.

Molecular characterization of Oryza sativa WRKY6, which binds to W-box-like element 1 of the Oryza sativa pathogenesis-related (PR) 10a promoter and confers reduced susceptibility to pathogens

The New phytologist, Jan 17, 2015

WRKY proteins are transcription factors (TFs) that regulate the expression of defense-related gen... more WRKY proteins are transcription factors (TFs) that regulate the expression of defense-related genes. The salicylic acid (SA)-inducible Oryza sativa WRKY6 (OsWRKY6) was identified as a positive regulator of Oryza sativa pathogenesis-related 10a (OsPR10a) by transient expression assays. A physical interaction between OsWRKY6 and W-box-like element 1 (WLE1), which positively regulates OsPR10a/probenazole induced protein 1 expression, was verified in vitro. Several pathogenesis-related (PR) genes were constitutively activated, including OsPR10a, and transgenic rice (Oryza sativa) plants overexpressing (ox) OsWRKY6 exhibited enhanced disease resistance to pathogens. By contrast, PR gene induction was compromised in transgenic OsWRKY6-RNAi lines, suggesting that OsWRKY6 is a positive regulator of defense responses. OsWRKY6-ox lines displayed leaf lesions, and increased OsWRKY6 levels caused cell death. Salicylic acid (SA) concentrations were higher in OsWRKY6-ox lines than in wild-type (W...

Size Dependence of Metal-Insulator Transition in Stoichiometric Fe3O4 Nanocrystals

Nano letters, Jan 16, 2015

Magnetite (Fe3O4) is one of the most actively studied materials with a famous metal-insulator tra... more Magnetite (Fe3O4) is one of the most actively studied materials with a famous metal-insulator transition (MIT), so-called the Verwey transition at around 123 K. Despite the recent progress in synthesis and characterization of Fe3O4 nanocrystals (NCs), it is still an open question how the Verwey transition changes on a nanometer scale. We herein report the systematic studies on size dependence of the Verwey transition of stoichiometric Fe3O4 NCs. We have successfully synthesized stoichiometric and uniform-sized Fe3O4 NCs with sizes ranging from 5 to 100 nm. These stoichiometric Fe3O4 NCs show the Verwey transition when they are characterized by conductance, magnetization, cryo-XRD, and heat capacity measurements. The Verwey transition is weakly size-dependent and becomes suppressed in NCs smaller than 20 nm before disappearing completely for less than 6 nm, which is a clear, yet highly interesting indication of a size effect of this well-known phenomena. Our current work will shed ne...

Neuropsychological effects of levetiracetam and carbamazepine in children with focal epilepsy

Neurology, Jan 9, 2015

To prospectively evaluate the neuropsychological effect of levetiracetam (LVT) in comparison with... more To prospectively evaluate the neuropsychological effect of levetiracetam (LVT) in comparison with carbamazepine (CBZ) and its efficacy and tolerability as a monotherapy in children with focal epilepsy. A total of 121 out of 135 screened children (4-16 years) were randomly assigned to LVT or CBZ groups in a multicenter, parallel-group, open-label trial. The study's primary endpoints were defined as the end of 52 weeks of treatment, followed by analysis of changes observed in a series of follow-up neurocognitive, behavioral, and emotional function tests performed during treatment in the per protocol population. Drug efficacy and tolerability were also analyzed among the intention-to-treat (ITT) population (ClinicalTrials.gov, number NCT02208492). Eighty-one patients (41 LVT, 40 CBZ) from the randomly assigned ITT population of 121 children (57 LVT, 64 CBZ) were followed up to their last visit. No significant worsening or differences were noted between groups in neuropsychological ...

NK cell function triggered by multiple activating receptors is negatively regulated by glycogen synthase kinase-3β

Cellular signalling, Jan 25, 2015

Activation of NK cells is triggered by combined signals from multiple activating receptors that b... more Activation of NK cells is triggered by combined signals from multiple activating receptors that belong to different families. Several NK cell activating receptors have been identified, but their role in the regulation of effector functions is primarily understood in the context of their individual engagement. Therefore, little is known about the signaling pathways broadly implicated by the multiple NK cell activation cues. Here we provide evidence pointing to glycogen synthase kinase (GSK)-3β as a negative regulator of multiple NK cell activating signals. Using an activation model that combines NKG2D and 2B4 and tests different signaling molecules, we found that GSK-3 undergoes inhibitory phosphorylation at regulatory serine residues by the engagement of NKG2D and 2B4, either individually or in combination. The extent of such phosphorylation was closely correlated with the degree of NK cell activation. NK cell functions, such as cytokine production and cytotoxicity, were consistentl...

Capacity Planning of OFDMA Cellular Networks with Decode-and-Forward Relaying

2008 IEEE Wireless Communications and Networking Conference, 2008

A Cycle-Accurate Energy Estimator for CMOS Digital Circuits

Lecture Notes in Computer Science, 2004

Cycle-accurate energy estimation is very useful in reducing the energy consumption in the CMOS di... more Cycle-accurate energy estimation is very useful in reducing the energy consumption in the CMOS digital circuits, which was reported in [1]–[3]. This paper introduces a measurement-based energy estimator, describes a new energy calculation method for the CMOS circuits. We found that instead of representing all load capacitance as a capacitor to ground, we should separate the capacitance to ground and that to supply for the precise energy estimation. The verification of the measurement system and calculation method was done through the experiment for the inverter with a known load capacitance. Then, we measured the base cost of the instructions of an ARM7 processor, and 4-bit counters implemented with an Altera’s APEX20K FPGA.

Robust coastal region detection method using image segmentation and sensor LOS information for infrared search and track

Automatic Target Recognition XXIII, 2013

ABSTRACT This paper presents a novel coastal region detection method for infrared search and trac... more ABSTRACT This paper presents a novel coastal region detection method for infrared search and track. The coastal region detection is critical to home land security and ship defense. Detected coastal region information can be used to the design of target detector such as moving target detection and threshold setting. We can detect coastal regions robustly by combining the infrared image segmentation and sensor line-of-sight (LOS) information. The K-means-based image segmentation can provide initial region information and the sensor LOS information can predict the approximate horizon location in images. The evidence of coastal region is confirmed by contour extraction results. The experimental results on remote coasts and near coasts validate the robustness of the proposed coastal region detector.

DNA-free genome editing in plants with preassembled CRISPR-Cas9 ribonucleoproteins

Nature biotechnology, Jan 19, 2015

Editing plant genomes without introducing foreign DNA into cells may alleviate regulatory concern... more Editing plant genomes without introducing foreign DNA into cells may alleviate regulatory concerns related to genetically modified plants. We transfected preassembled complexes of purified Cas9 protein and guide RNA into plant protoplasts of Arabidopsis thaliana, tobacco, lettuce and rice and achieved targeted mutagenesis in regenerated plants at frequencies of up to 46%. The targeted sites contained germline-transmissible small insertions or deletions that are indistinguishable from naturally occurring genetic variation.

[Antibiotics-associated diarrhea and other gastrointestinal abnormal responses regarding Helicobacter pylori eradication]

The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi, 2010

Helicobacter pylori (H. pylori) is closely related with a wide range of gastrointestinal disease.... more Helicobacter pylori (H. pylori) is closely related with a wide range of gastrointestinal disease. One-week triple therapy is currently considered as the golden standard for the treatment of H. pylori infection. However, gastrointestinal abnormal responses are major pitfalls in such regimen. The aim of this study was to identify symptoms, frequency and severity of antibiotics-associated gastrointestinal abnormal responses during H. pylori eradication therapy. Sixty-seven patients with H. pylori infection between September 2005 and March 2006 were included. After 1 week of H. pylori eradication triple therapy (rabeprazol 10 mg, clarithromycin 500 mg, amoxicillin 1 g bid), we evaluated gastrointestinal abnormal responses (diarrhea, bloating, constipation, abdominal pain, borborygmus, flatulence, stool frequency, belching, and nausea) and severities every week for 4 weeks. The incidence of diarrhea was the highest in week 1, which was 41.28% (n=28) and the lowest in week 4, which was 9....

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