• Journal of the Korean Ceramic Society
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• v.30 no.3
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• pp.229-235
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• 1993

Thermal history and thermal stress of alumina specimen, which occured from thermal shock process, were calculated by finite difference method. Stress intensity factor and crack growth in cyclic thermal fatigue were calculated from single thermal shock temperature history and thermal stress. Cyclic thermal life were estimated by bending strength after cyclic thermal shock under critical thermal shock temperature. Calculated stress intensity factor was compared with real experimental thermal fatigue life of specimen. Fatigue life until critical stress intensity factor and real experimental result were comparable.

• Journal of applied mathematics & informatics
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• v.6 no.1
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• pp.31-50
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• 1999

We revisit the problems of testing three-factor classifica-tion models with a single observation per cell. A common approach in analyzing such nonreplicated data is to omit the highest order in-teraction and regard it as error. This paper discusses the use of a multiplicative model(See and Smith 1996 and 1998) which is applied on residuals in order to separate the variablility due to three-factor interaction from what is counted as random error. in particualr to test the significance of the interaction term we derived an approxi-mated distribution of the likelihood ratio test statistic based on the quadrilinear model known as Tucher's three-mode principal compo-nent model. The derivation utilizes the distribution of the eignevalues of the Wishart matrix.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.25-30
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• 2000

Plate and shell heat exchanger(P&SHE) has been applied to the refrigeration and air conditioning systems as evaporators or condensers fur their high efficiency and compactness. The purpose of this study is to analyze the characteristics of pressure drop in plate and shell heat exchanger. An experiment for single phase (low pressure drop in plate and shell heat exchanger was performed. Also numerical work was conducted using the FLUENT code for $ {\kappa}-{\varepsilon}$ model. The dependence of friction factor on geometrical Parameters was numerically investigated. The study examines the internal flow and the pressure distribution in the channel of plate and shell heat exchanger. The results of CFD analysis compared with experimental data, and the difference of frictor factor in plate side and shell side are 10% and 12%, respectively. Therefore, the CFD analysis model is effectively predict the performance of plate and shell heat exchanger.

• Structural Engineering and Mechanics
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• v.71 no.3
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• pp.245-255
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• 2019

In this paper, an inverted-pendulum model consisting of a point supported by spring limbs with roller feet is adopted to simulate human walking load. To establish the kinematic motion of first and second single and double support phases, the Lagrangian variation method was used. Given a set of model parameters, desired walking speed and initial states, the Newmark-${\beta}$ method was used to solve the above kinematic motion for studying the effects of roller radius, stiffness, impact angle, walking speed, and step length on the ground reaction force, energy transfer, and height of center of mass transfer. The numerical simulation results show that the inverted-pendulum model for walking is conservative as there is no change in total energy and the duration time of double support phase is 50-70% of total time. Based on the numerical analysis, a dynamic load factor ${\alpha}_{wi}$ is proposed for the traditional walking load model.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.228-235
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• 2002

As the response spectrum method generally used in the earthquake resistant design is a linear method, the nonlinear behavior of a structure is to be reflected with a specific factor. Such factors are provided in the "Design Criteria for Roadwaybridges"as response modification factors and in the Eurocode 8, Part 2 as behavior factors. In this study a 5-span steel box bridge with single column piers is selected and the behavior factor is determined. The linear time history analyses are carried out with a simple linear model, where the nonlinear behavior of piers leading to the ductile failure mechanism is considered as predetermined characteristic curves.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.161-165
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• 2003

In this paper, A new controller for power factor and harmonics compensation of a single-phase PWM converter is described. The proposed controller requires only the dc voltage sensor and the at current sensor to compensate the power factor and harmonics. Detail simulation model with EMTBC (Electro-Magnetic Transient program for DC transmission) including power circuit and controller was developed to verify the operation of proposed controller. The application feasibility of the proposed controller was verified through experimental works with a prototype. The proposed controller has a simple structure in the point of hardware implementation, and shows excellent performance in normal operation as well as in sudden load change.

• Journal of Power Electronics
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• v.11 no.1
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• pp.105-111
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• 2011

By having accurate knowledge of the magnetic field distribution and the thrust calculation in linear synchronous motors, assessing the performance and optimization of the motor design are possible. In this paper, after carrying out a performance analysis of a single-sided wound secondary linear synchronous motor by varying the motor design parameters in a layer model and a d-q model, machine single- and multi-objective design optimizations are carried out to improve the thrust density of the motor based on the motor weight and the motor efficiency multiplied by its power factor by defining various objective functions including a flexible objective function. A genetic algorithm is employed to search for the optimal design. The results confirm that an overall improvement in the thrust mean, efficiency multiplied by the power factor, and thrust to the motor weight ratio are obtained. Several design conclusions are drawn from the motor analysis and the design optimization. Finally, a finite element analysis is employed to evaluate the effectiveness of the employed machine models and the proposed optimization method.

• The Korean Journal of Applied Statistics
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• v.29 no.1
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• pp.75-83
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• 2016

We propose methodology to analyze the dynamic mechanisms of financial market contagion under market integration using a biological contagion analytical approach. We employ U-statistic to measure market integration, and a dynamic model based on an error correction mechanism (single equation error correction model) and latent factor model to examine market contagion. We also use quantile regression and Wald-Wolfowitz runs test to test market contagion. This methodology is designed to effectively handle heteroscedasticity and correlated errors. Our simulation results show that the single equation error correction model fits well with the linear regression model with a stationary predictor and correlated errors.

• Journal of the Korean Statistical Society
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• v.29 no.1
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• pp.81-94
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• 2000

For the balanced variance component model, sometimes intraclass correlation coefficient is of interest. If there is little information about the parameter, then the reference prior(Berger and Bernardo, 1992) is widely used. Pettit nd Young(1990) considered a measrue of the effect of a single observation on a logarithmic Bayes factor. However, under such a reference prior, the Bayes factor depends on the ratio of unspecified constants. In order to discard this problem, influence diagnostic measures using the intrinsic Bayes factor(Berger and Pericchi, 1996) is presented. Finally, one simulated dataset is provided which illustrates the methodology with appropriate simulation based computational formulas. In order to overcome the difficult Bayesian computation, MCMC methods, such as Gibbs sampler(Gelfand and Smith, 1990) and Metropolis algorithm, are empolyed.

• Clinical and Experimental Pediatrics
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• v.56 no.3
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• pp.116-124
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• 2013

Purpose: Tumor necrosis factor (TNF)-${\alpha}$ is thought to contribute to pulmonary hypertension. We aimed to investigate the effect of infliximab (TNF-${\alpha}$ antagonist) treatment on pathologic findings and gene expression in a monocrotaline-induced pulmonary hypertension rat model. Methods: Six-week-old male Sprague-Dawley rats were allocated to 3 groups: control (C), single subcutaneous injection of normal saline (0.1 mL/kg); monocrotaline (M), single subcutaneous injection of monocrotaline (60 mg/kg); and monocrotaline + infliximab (M+I), single subcutaneous injection of monocrotaline plus single subcutaneous injection of infliximab (5 mg/kg). The rats were sacrificed after 1, 5, 7, 14, or 28 days. We examined changes in pathology and gene expression levels of TNF-${\alpha}$, endothelin-1 (ET-1), endothelin receptor A (ERA), endothelial nitric oxide synthase (eNOS), matrix metalloproteinase (MMP) 2, and tissue inhibitor of matrix metalloproteinase (TIMP). Results: The increase in medial wall thickness of the pulmonary arteriole in the M+I group was significantly lower than that in the M group on day 7 after infliximab treatment (P<0.05). The number of intraacinar muscular arteries in the M+I group was lower than that in the M group on days 14 and 28 (P<0.05). Expression levels of TNF-${\alpha}$, ET-1, ERA, and MMP2 were significantly lower in the M+I group than in the M group on day 5, whereas eNOS and TIMP expressions were late in the M group (day 28). Conclusion: Infliximab administration induced early changes in pathological findings and expression levels of TNF-${\alpha}$, and MMP2 in a monocrotaline-induced pulmonary hypertension rat model.