• Structural Engineering and Mechanics
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• 제17권5호
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• pp.671-690
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• 2004

A meshless method with novel variation of point collocation by finite mixture approximation is developed in this paper, termed the meshless finite mixture (MFM) method. It is based on the finite mixture theorem and consists of two or more existing meshless techniques for exploitation of their respective merits for the numerical solution of partial differential boundary value (PDBV) problems. In this representation, the classical reproducing kernel particle and differential quadrature techniques are mixed in a point collocation framework. The least-square method is used to optimize the value of the weight coefficient to construct the final finite mixture approximation with higher accuracy and numerical stability. In order to validate the developed MFM method, several one- and two-dimensional PDBV problems are studied with different mixed boundary conditions. From the numerical results, it is observed that the optimized MFM weight coefficient can improve significantly the numerical stability and accuracy of the newly developed MFM method for the various PDBV problems.

• 한국세라믹학회지
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• 제52권2호
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• pp.133-136
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• 2015

The outward diffusion of $Na^+$ ions in iron-bearing soda lime silicate glass via oxidation heat treatment before the ion exchange process is artificially induced in order to increase the amount of ions exchanged during the ion exchange process. The effect of the addition process is analyzed through measuring the bending strength, the weight change, and the inter-diffusion coefficient after the ion exchange process. The glass strength is increased when the outward diffusion of $Na^+$ ions via oxidation heat treatment before the ion exchange process is added. For the glass subjected to the additional process, the weight change and diffusion depth increase compared with the glass not subjected to the process. The interdiffusion coefficient is also slightly increased as a result of the additional process.

• Journal of the Korean Data and Information Science Society
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• 제17권3호
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• pp.775-784
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• 2006

This study is to investigate the effect of the number of co-rated users to the MAE. User based collaborative algorithm generally uses similarity weight to compute the relation of active user and other users. The original estimation algorithm of the GroupLens used the Pearson's correlation coefficient, soon after other researchers used various weighting. The Pearson’s correlation coefficient and Vector similarity, which is used in the field of information retrieval, are commonly used to the estimation algorithm. In prediction, we analyze the effect of the number of co-rated users on the user based recommender system.

• Structural Engineering and Mechanics
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• 제85권5호
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• pp.645-654
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• 2023

Based on first-order shear deformation theory, a wave propagation model of graphene platelets reinforced metal foams (GPLRMFs) circular plates is built in this paper. The expressions of phase-/group- velocities and wave number are obtained by using Laplace integral transformation and Hankel integral transformation. The effects of GPLs pattern, foams distribution, GPLs weight fraction and foam coefficient on the phase and group velocity of GPLRMFs circular plates are discussed in detail. It can be inferred that GPLs distribution have great impacts on the wave propagation problems, and Porosity-I type distribution has the largest phase velocity and group velocity, followed by Porosity-III, and finally Porosity-II; With the increase of the GPLs weight fraction, the phase- and group- velocities for the GPLRMFs circular plate will be increased; With the increase of the foam coefficient, the phase- and group- velocities for the GPLRMFs circular plate will be decreased.

• 대한간호학회지
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• 제21권2호
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• pp.195-203
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• 1991

Correlations among body weight and sociodemographic factors, including life - style were tested as social determinants of health in a sample of 5,201 adults in Korea. The aim of this study was to determine the extent to which sociodemographic variables and life-style associated health behaviors explain body weight distribution. A second aim was to explain the relation of body weight and health status to stress the importance of body weight as an early risk indicator of health status. The canonical correlation between the weight distribution(underweight and overweight) and the independent variables was 0.29, 17% of the total variance was explained. Perceived health level represented the highest contribution(canonical coefficient 0.82) to body weight. Sociodemographic factors such as sex, economic status, and life-style factors such as smoking, exercise, regular meais and sleep showed comparatively high contributions to body weight. The relevance of body weight for health status including the rate of chronic disease and the rate of medical utilization was significant. Especially, underweight was clarified as being mere important than overweight to morbidity level and medical utilization. These findings suggest that perceived body weight is an important indicator of health status and is thus a valuable variable to be considered for nursing intervention and health education related to the promotion of health.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1996년도 창립기념 전력전자학술발표회 논문집
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• pp.47-51
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• 1996

In this paper, we propose a method for compliance control of a SCARA type 2-freedom direct drive(DD) manipulator. Each joint of the manipulator is driven by a travelling ultrasonic motor(USM). The travelling USM has good some characteristics over conventional servo motors such as compact size, light weight, silent motion, high torque and high speed response. By controlling the elasticity and viscosity of robot joints, a robot can work in compliance with external environment. we control the elastic coefficient and the viscous coefficient of joint by adjusting the phase difference of the motor power. And we contemplate transient response of USM with adjusting the elastic coefficient and the viscous coefficient. To use the result, we can control the robot to reach its goal with compliance motion. It remains for further research to develop the impedance control of USM.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.678-683
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• 2004

The most popular consolidation tester is a standard consolidatiion tester, which performs consolidation using the step load weight. However this apparatus is used to obtain only the vertical consolidation coefficient. Therefore the purpose of this study is to develope the horizontal consolidation cell for a horizaontal consolidation coefficient. Various size of tests have been peroformed to investigate the effect of scale effect. From the test results, it has turned out that this horizontal consolidation cell has a good function for a horizontal consolidation coefficient.

• 한국표면공학회지
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• 제36권1호
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• pp.99-107
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• 2003

The diffusion coefficient of Xe-133 was obtained from an annealing test. The specimens were made from a UO$_2$ single crystal powder with natural enrichment. Weight and grain size were 300mg and ($23\mu\textrm{m}$, respectively. Oxygen potentials were obtained from an oxygen sensor. Released fractions were obtained from both results of gamma scans and quantitative analysis with MCNP code, The annealing test was performed at three temperatures at once. Diffusion coefficients of Xe-133 were calculated using slope of Booth theory in each O/M ratios. Activation energy and the pre-exponential factor of the diffusion coefficient were obtained. The activation energy of near stoichiomeric $UO_2$ is 310 kJ/mol. The measured values of near stoichiometric $UO_2$ are very close to other data available. Diffusion coefficients increase with hyper-stoichiometry, due to higher concentration of cation vacancies.

• 한국대기환경학회지
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• 제17권5호
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• pp.415-424
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• 2001

The concentrations of PCBs (polychlorinated biphenyls) in air and plants (MOrus allba, Allum turberosum) were measured every other week at Hankyong University located in Ansung, Kyoung-ki province, Korea from July to November in 1999. Total concentrations of PCBs in air ranged from 19.8 to 71.9 pg/ $m^3$. It was observed in air that the concentrations of tai-chlorinated biphenyls(CBs) were higher than those of other PCB homologs probably due to their higher vapor pressure. Total concentrations of PCBs in plants ranged from 24.5 to 1,287 pg/g dry weight for Morus allba and 26.5 to 337 pg/g dry weight for Allum turberosum. A positive linear correlation was observed between log plant-air partition coefficients ( $m^3$air/g plant dry weight-defined here as the scavenging coefficient[S.C]) and log octanol-air partition coefficients ( $K_{oa}$ ) for each plant. In this study, slope of log S.C and log $K_{oa}$ for Morus allba, Allum turberosum were 1.07 ($R^2$= 0.83, p<0.01), 0.84 ($R^2$=0.53, p<0.05), respectively. This means that these plants may approach to equilibrium for air-plant partitioning.

• ETRI Journal
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• 제28권1호
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• pp.59-66
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• 2006

Learning behaviors of a radial basis function network (RBFN) using a singular value decomposition (SVD) and stochastic gradient (SG) algorithm, together named RBF-SVD-SG, for odor sensing systems are analyzed, and a fast training method is proposed. RBF input data is from a conducting polymer sensor array. It is revealed in this paper that the SG algorithm for the fine-tuning of centers and widths still shows ill-behaving learning results when a sufficiently small convergence coefficient is not used. Since the tuning of centers in RBFN plays a dominant role in the performance of RBFN odor sensing systems, our analysis is focused on the center-gradient variance of the RBFN-SVD-SG algorithm. We found analytically that the steadystate weight fluctuation and large values of a convergence coefficient can lead to an increase in variance of the center-gradient estimate. Based on this analysis, we propose to use the least mean square algorithm instead of SVD in adjusting the weight for stable steady-state weight behavior. Experimental results of the proposed algorithm have shown faster learning speed and better classification performance.