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Search Results: 1 - 10 of 25360 matches for " Jinho Lee "
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A Study on the Dynamic Behavior of Wheel-Type Train Propelled by Superconducting Linear Synchronous Motor  [PDF]
Jinho Lee, Changyoung Lee, Jeongmin Jo, Yongjae Han
Modern Mechanical Engineering (MME) , 2014, DOI: 10.4236/mme.2014.43014
Abstract:
This paper deals with a study on the dynamic behavior of 600 km/h wheel-type train propelled by superconducting linear synchronous motor (LSM). This train is of a traditional wheel-on-rail type with traction motors on wheel-bogies. However, for the 600 km/h speed, on the both sides of each vehicle, superconducting LSMs are attached and the ground coils are installed on the guideway. In this case, the guideway irregularities act as disturbance to the vehicle causing deterioration of ride comfort. And besides thrust force, the normal force could be created in superconducting LSM control, which influences vehicle dynamics during running. In this study, to examine the effect of guideway irregularity and normal force on dynamic behavior of proposed train, the vehicle dynamic model is driven and frequency analysis is performed through simulation. The simulation results show that the lateral directional acceleration is mainly influential to ride comfort; however this could be reduced effectively by electromagnetic damping force from linear generator. It is also shown that the normal force effect from superconducting LSM control is limited even though the attractive normal force acts favorably to ride comfort.
A Study on the Sensor Applications for Position Detection and Guideway Monitoring in High Speed Maglev  [PDF]
Jinho Lee, Jeongmin Jo, Yongjae Han, Changyoung Lee, Yan Sun
Modern Mechanical Engineering (MME) , 2014, DOI: 10.4236/mme.2014.44016
Abstract: The high speed maglev is mainly characterized by propulsion using linear synchronous motor (LSM) and vehicle levitation from the guideway surface. In LSM propulsion control, the position detection sensor is used to detect running vehicle position for synchronized current generation. To maintain the stable levitating condition during vehicle running, the irregularity of guideway surface should be monitored by sensors measuring the displacement and acceleration between vehicle and guideway. In this study, the application methods of these sensors in the high speed maglev are investigated and through the experiments by using the small-scale test bed, the validity of examined methods is confirmed.
Fluctuations of the free energy of the spherical Sherrington-Kirkpatrick model
Jinho Baik,Ji Oon Lee
Mathematics , 2015,
Abstract: The spherical Sherrington-Kirkpatrick model is a spherical mean field model for spin glass. We consider the fluctuations of the free energy at arbitrary non-critical temperature for the 2-spin model with no magnetic field. We show that in the high temperature regime the law of the fluctuations converges to the Gaussian distribution just like in the Sherrington-Kirtkpatrick model. We show, on the other hand, that the law of the fluctuations is given by the GOE Tracy-Widom distribution in the low temperature regime. The orders of the fluctuations are markedly different in these two regimes. A universality of the limit law is also proved.
Atrial fibrillation detection by heart rate variability in Poincare plot
Jinho Park, Sangwook Lee, Moongu Jeon
BioMedical Engineering OnLine , 2009, DOI: 10.1186/1475-925x-8-38
Abstract: We analyzed heart beat variability from inter-beat intervals obtained by a wavelet-based detector. We made a Poincare plot using the inter-beat intervals. By analyzing the plot, we extracted three feature measures characterizing AFib and non-AFib: the number of clusters, mean stepping increment of inter-beat intervals, and dispersion of the points around a diagonal line in the plot. We divided distribution of the number of clusters into two and calculated mean value of the lower part by k-means clustering method. We classified data whose number of clusters is more than one and less than this mean value as non-AFib data. In the other case, we tried to discriminate AFib from non-AFib using support vector machine with the other feature measures: the mean stepping increment and dispersion of the points in the Poincare plot.We found that Poincare plot from non-AFib data showed some pattern, while the plot from AFib data showed irregularly irregular shape. In case of non-AFib data, the definite pattern in the plot manifested itself with some limited number of clusters or closely packed one cluster. In case of AFib data, the number of clusters in the plot was one or too many. We evaluated the accuracy using leave-one-out cross-validation. Mean sensitivity and mean specificity were 91.4% and 92.9% respectively.Because pulse beats of ventricles are less likely to be influenced by baseline wandering and noise, we used the inter-beat intervals to diagnose AFib. We visually displayed regularity of the inter-beat intervals by way of Poincare plot. We tried to design an automated algorithm which did not require any human intervention and any specific threshold, and could be installed in a portable AFib monitoring system.There is a growing tendency that atrial fibrillation (AFib) related disease affects quality of life. Its risk increases with age [1]; in fact, AFib is one of the most common types of arrhythmia in clinical practice [2]. Blood circulation of AFib patients is not sm
Comparative Study of Various Preparation Methods of Colloidal Silica  [PDF]
Hyung Mi Lim, Jinho Lee, Jeong-Hwan Jeong, Seong-Geun Oh, Seung-Ho Lee
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.212126
Abstract: Colloidal silica can be prepared by various methods and starting materials including ion exchange of aqueous silicates, hydrolysis and condensation of silicon compounds, direct oxidation of silicon, and milling and peptization of silica powder. Various silica sols having particle sizes of 10-60 nm prepared by these methods and the preparation methods have been compared on the basis of their shape, size uniformity, sphericity, stability against pH variation, cation concentration, and price, etc. Silica sol prepared from tetraethoxysilane affords uniform size control and growth, and high purity, despite the relatively high costs. Silica sol prepared from liquid silicates affords relatively easy size and shape control; however, it is difficult to lower the alkali content to a level that is appropriate for carrying out semiconductor chemical mechanical polishing processes; in addition, the waste water treatment carried out for recovering the ion exchange resin gives rise environmental consideration. The properties of colloidal silica prepared from fumed silica powder by milling and dispersion depend on the starting silica source and it is relatively difficult to obtain monodispersed particles using this method. Colloidal silica prepared from silicon by direct oxidation has a monodispersed spherical shape and purity control with reasonable prices. It generates less waste water because it can be directly produced in relatively high concentrations. The cation fraction located in the particle relative to the free cation in the fluid is relatively lower in the silica sol prepared by the direct oxidation than others. A careful comparison of colloidal silica and the preparation methods may help in choosing the proper colloidal silica that is the most appropriate for the application being considered.
Axisymmetric Stagnation Flow of a Micropolar Nanofluid in a Moving Cylinder
S. Nadeem,Abdul Rehman,K. Vajravelu,Jinho Lee,Changhoon Lee
Mathematical Problems in Engineering , 2012, DOI: 10.1155/2012/378259
Abstract: An analysis is carried out for axisymmetric stagnation flow of a micropolar nanofluid in a moving cylinder with finite radius. The coupled nonlinear partial differential equations of the problem are simplified with the help of similarity transformations and the resulting coupled nonlinear differential equations are solved analytically by homotopy analysis method (HAM). The features of the flow phenomena, inertia, heat transfer, and nanoparticles are analyzed and discussed.
Boundary Layer Flow of Second Grade Fluid in a Cylinder with Heat Transfer
S. Nadeem,Abdul Rehman,Changhoon Lee,Jinho Lee
Mathematical Problems in Engineering , 2012, DOI: 10.1155/2012/640289
Abstract: An analysis is carried out to obtain the similarity solution of the steady boundary layer flow and heat transfer of a second grade through a horizontal cylinder. The governing partial differential equations along with the boundary conditions are reduced to dimensionless form by using the boundary layer approximation and applying suitable similarity transformation. The resulting nonlinear coupled system of ordinary differential equations subject to the appropriate boundary conditions is solved by homotopy analysis method (HAM). The effects of the physical parameters on the flow and heat transfer characteristics of the model are presented. The behavior of skin friction coefficient and Nusselt numbers is studied for different parameters.
SNPAnalyzer 2.0: A web-based integrated workbench for linkage disequilibrium analysis and association analysis
Jinho Yoo, Youngbok Lee, Yujung Kim, Sun Rha, Yangseok Kim
BMC Bioinformatics , 2008, DOI: 10.1186/1471-2105-9-290
Abstract: We have developed an advanced tool to perform linkage disequilibrium analysis, and genetic association analysis between disease and SNPs/haplotypes in an integrated web interface. It comprises of four main analysis modules: (i) data import and preprocessing, (ii) haplotype estimation, (iii) LD blocking and (iv) association analysis. Hardy-Weinberg Equilibrium test is implemented for each SNPs in the data preprocessing. Haplotypes are reconstructed from unphased diploid genotype data, and linkage disequilibrium between pairwise SNPs is computed and represented by D', r2 and LOD score. Tagging SNPs are determined by using the square of Pearson's correlation coefficient (r2). If genotypes from two different sample groups are available, diverse genetic association analyses are implemented using additive, codominant, dominant and recessive models. Multiple verified algorithms and statistics are implemented in parallel for the reliability of the analysis.SNPAnalyzer 2.0 performs linkage disequilibrium analysis and genetic association analysis in an integrated web interface using multiple verified algorithms and statistics. Diverse analysis methods, capability of handling huge data and visual comparison of analysis results are very comprehensive and easy-to-use.Since the completion of the HapMap project, huge numbers of individual genotypes have been generated from many kinds of laboratories. The efforts of finding or interpreting genetic association between disease and SNPs/haplotypes have been on-going widely, and the necessity of the capability to analyze huge data and diverse interpretation of the result are growing rapidly. Recently developed software programs are well suited for constructing linkage disequilibrium blocks, estimating haplotypes or detecting genetic association between disease and SNPs [1-6]. However, some software programs have drawbacks such as long computation time for the association analysis [1], limited size of dataset [1,2], inconvenient user in
Study of the Coil Structure for Wireless Chip-to-Chip Communication Applications
Changhyun Lee;Jonghoon Park;Jinho Yoo;Changkun Park
PIER Letters , 2013, DOI: 10.2528/PIERL13022002
Abstract: In this work, we propose a merged coil structure for wireless chip-to-chip communication technology. Using the proposed coil structure, the chip size can be reduced, and the transmitted power can be improved by approximately 5 dB compared to typical coil structure. To verify the feasibility of the coil, an electromagnetic simulation and a schematic simulation are performed. The coil was implemented using 50-nm digital CMOS technology. From the experimental results, the feasibility was proved.
Three-Dimensional Object Motion and Velocity Estimation Using a Single Computational RGB-D Camera
Seungwon Lee,Kyungwon Jeong,Jinho Park,Joonki Paik
Sensors , 2015, DOI: 10.3390/s150100995
Abstract: In this paper, a three-dimensional (3D) object moving direction and velocity estimation method is presented using a dual off-axis color-filtered aperture (DCA)-based computational camera. Conventional object tracking methods provided only two-dimensional (2D) states of an object in the image for the target representation. The proposed method estimates depth information in the object region from a single DCA camera that transforms 2D spatial information into 3D model parameters of the object. We also present a calibration method of the DCA camera to estimate the entire set of camera parameters for a practical implementation. Experimental results show that the proposed DCA-based color and depth (RGB-D) camera can calculate the 3D object moving direction and velocity of a randomly moving object in a single-camera framework.
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