• Journal of Digital Convergence
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• v.13 no.9
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• pp.209-218
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• 2015

Computer simulation plays an important role for a theoretical foundation in convergence technology and the interpolation is to know the unknown values from known values on grid points. Therefore it is an important problem to select an interpolation method for digital simulation. The aim of this paper is to compare analysis of interpolation methods for digital simulation. we test six different interpolation methods namely: Quartic-Lagrangian, Cubic Spline, Fourier, Hermit, PWENO and SL-WENO. Through digital simulation of a linear advection equation, we analyse pros and cons for each method. In order to compare performance, we introduce accuracy computing and Error functions. The accuracy computing is used well-known $L^1-norm$ and the Error functions are dispersion function, dissipation function and total error function. High-order methods well apply to computer simulation, unfortunately, side-effects (Oscillation) happen.

• Imaging Science in Dentistry
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• v.48 no.1
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• pp.51-57
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• 2018

Purpose: To perform a comparative analysis of the palatal bone thickness in Thai patients exhibiting class I malocclusion according to whether they exhibited a normal or open vertical skeletal configuration using cone-beam computed tomography (CBCT). Materials and Methods: Thirty CBCT images of Thai orthodontic patients (15-30 years of age) exhibiting class I malocclusion with a normal or open vertical skeletal configuration were selected. Palatal bone thickness was measured in a 3.0-mm grid pattern on both the right and left sides. The palatal bone thickness of the normal-bite and open-bite groups was compared using the independent t-test. The level of significance was established at P<.05. Results: The palatal bone thickness in the normal-bite group ranged from $2.2{\pm}1.0mm$ to $12.6{\pm}4.1mm$. The palatal bone thickness in the open-bite group ranged from $1.9{\pm}1.1mm$ to $13.2{\pm}2.3mm$. The palatal bone thickness was lower at almost all sites in patients with open bite than in those with normal bite. Significant differences were found at almost all anteroposterior sites along the 3 most medial sections (3.0, 6.0, and 9.0 mm lateral to the midsagittal plane)(P<.05). Conclusion: Class I malocclusion with open vertical skeletal configuration may affect palatal bone thickness, so the placement of temporary anchorage devices or miniscrew implants in the palatal area in such patients should be performed with caution.

• The Journal of Society for e-Business Studies
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• v.14 no.3
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• pp.59-70
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• 2009

By the time the interest on the u-City is continuously growing as a test bed for verifying the potentials of ubiquitous convergence industries, research on the u-Safety gradually increases as well, as a typical service and application area of u-City. Like the other service areas of u-City, in order to provide u-Safety services smoothly, it is crucial to integrally connect u-City services and infrastructures that have operated under distributed environment. In this study, we suggest an approach for design of u-Safety service and monitoring architecture by combing CIM/WBEM standard with GMA. CIM/WBEM and GMA are broadly applied in the distributed resource monitoring environment and are widely recognized as data acquisition architecture under massive monitoring data volumes respectively. Considering the growing research needs for standardization and extension of u-City service infrastructure, it is expected that our integrated infrastructure model will be used as a reference model for effective integration of distributed resources with newly added services.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.700-711
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• 2015

Sodium-cooled fast breeder reactors use liquid sodium as a moderator and coolant to transfer heat from the reactor core. The main hazard associated with sodium is its rapid reaction with water. Sodium-water reaction (SWR) takes place when water or vapor leak into the sodium side through a crack on a heat-transfer tube in a steam generator. If the SWR continues for some time, the SWR will damage the surface of the defective area, causing it to enlarge. This self-enlargement of the crack is called "self-wastage phenomena." A stepwise numerical evaluation model of the self-wastage phenomena was devised using a computational code of multicomponent multiphase flow involving a sodium-water chemical reaction: sodiumwater reaction analysis physics of interdisciplinary multiphase flow (SERAPHIM). The temperature of gas mixture and the concentration of NaOH at the surface of the tube wall are obtained by a numerical calculation using SERAPHIM. Averaged thermophysical properties are used to assess the local wastage depth at the tube surface. By reflecting the wastage depth to the computational grid, the self-wastage phenomena are evaluated. A two-dimensional benchmark analysis of an SWAT (Sodium-Water reAction Test rig) experiment is carried out to evaluate the feasibility of the numerical model. Numerical results show that the geometry and scale of enlarged cracks show good agreement with the experimental result. Enlarged cracks appear to taper inward to a significantly smaller opening on the inside of the tube wall. The enlarged outer diameter of the crack is 4.72 mm, which shows good agreement with the experimental data (4.96 mm).

• Journal of the Korea Institute of Building Construction
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• v.13 no.4
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• pp.382-390
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• 2013

Recently, the housing problem has been recognized as a matter of housing supply with a certain environmental level and not simply a matter of handing as a quantitative problem, and the demand for pleasant residential environments and requirements for residential environments are increasing more and more. However, it is necessary to establish the directions for improvement of the residential environment according to the house type, as the requirements and levels of satisfaction differ. This study aimed to deduce the level of resident satisfaction with the residential environments according to house type, and determine the direction for improvement of the residential environment. To achieve this, the difference between the house types was analyzed through ANOVA analysis and T-Test, and the major factors on the improvement direction of the residential environment were derived through Action-grid analysis.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.1
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• pp.7-11
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• 2009

In this study, solder joints were made with Sn-3.5Ag (wt%) solder ball. Electroless nickel / immersion gold (ENIG) printed circuit board (PCB) substrates were employed in this work. The mechanical and electrical properties were measured as a function of the number of reflow. Die shear strength was measured with increasing reflow number. Until the forth or fifth reflow, shear force increased and after the fifth reflow the shear force of die decreased. The electrical resistivity of solder joint linearly increased with increasing reflow number.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1682-1691
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• 2018

Natural ester is a suitable substitute for mineral oil and has been widely used in AC transformer in many countries. In order to further application of natural ester in direct current (DC) equipment, it is needed to investigate its long term insulation property under DC condition. In this paper, a thermal ageing experiment was conducted for both mineral oil-paper and natural ester-paper insulation. The DC breakdown and space charge characteristics of insulation paper impregnated with natural ester and mineral oil was compared. Results show that the resistivity of the paper immersed in natural ester and mineral oil both increase as the ageing goes on. While insulation paper impregnated with natural ester has higher resistivity and DC breakdown voltage than the paper impregnated with mineral oil. The DC breakdown voltage for the oil impregnated insulation paper being DC pre-stressing is higher than that without pre-stressing. The average DC breakdown field strength difference between the test with pre-stressing and without pre-stressing clearly shows that there is an apparent enhancement effect for the homo-charge injection on the DC breakdown.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.9
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• pp.522-529
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• 2002

In this paper, computer simulations of the physical Phenomena occurring in the arc region before and after current zero were carried out to evaluate the thermal recovery characteristics of a Laval nozzle. A commercial CFD program "PHOENICS" is used for the simulation and the user-coded subroutines to consider the arcing phenomena were added to this program by the authors. The computed results were verified by the comparison with the test results presented by the research group of GE Co.(General Electric Company). In order to investigate the state of the arc region after current zero, the simulation was carried out with three steps. They are steady state arc simulation, transient arc simulation before current zero, and transient hot-gas flow simulation after current zero. The semi-experimental arc radiation model is adapted to consider the radiation energy transport and Prandtl's mixing length model is employed as the turbulence model. The electric field and the magnetic field were calculated with the same grid structure used for the simulation of the flow field. The post-arc current was calculated to evaluate the thermal recovery characteristics after current zero. Compared with the results obtained by GE Co., it has been found that the critical RRRV(ratio of rise of recovery voltage) will be determined previously by this study.his study.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.4
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• pp.266-273
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• 2010

The main function of the power conditioning system (PCS) is grid-connection with renewable system. The level of total harmonic distortion(THD) caused by the PCS should be maintained less than 5% according to the IEEE-1547 regulation. The THD is measured by the dedicated instrument, not by the PCS in the domestic products. There should be the necessity for harmonic measurement by the PCS in order to cope with degradation or fault condition. In this paper, the real-time harmonic measurement technique using highperformance DSP controller is presented. The proto-system is manufactured using 32-bit floating DSP processor and tested with 256-point DFT(Discrete Fourier Transform) algorithm. The test result shows that the harmonic calculation time is less than 1 [ms]. It can be used as a auxiliary method for predicting the fault in the PCS system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.10
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• pp.984-991
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• 2009

In this study, transonic aeroelastic response analyses have been conducted for the DLR-F4(wing-body) aircraft configuration considering shockwave and flow separation effects. The developed fluid-structure coupled analysis system is applied for aeroelastic computations combining computational structural dynamics(CSD), finite element method(FEM) and computational fluid dynamics(CFD) in the time domain. It can give very accurate and useful engineering data on the structural dynamic design of advanced flight vehicles. For the nonlinear unsteady aerodynamics in high transonic flow region, Navier-Stokes equations using the structured grid system have been applied to wing-body configurations. In transonic flight region, the characteristics of static and dynamic aeroelastic responses have been investigated for a typical wing-body configuration model. Also, it is typically shown that the current computation approach can yield realistic and practical results for aircraft design and test engineers.