• Journal of the Korean Data and Information Science Society
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• v.21 no.6
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• pp.1311-1317
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• 2010

A continuous time asymmetric power GARCH(1,1) model is suggested, based on a single background driving L$\'{e}$vy process. The stochastic differential equation for the given process is derived and the strict stationarity and kth order moment conditions are examined.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.1215-1217
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• 1993

In this paper, we reason about the fuzzy dynamic equation based on L-R type fuzzy number, analyze and solve the fuzzy dynamic property and the fuzzy dynamic response of singledegree of freedom system. Specific expressions of fuzzy dynamic response are response.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.7
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• pp.283-288
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• 1985

This paper is concerned with the analysis of microprocessor-based PID control for the current source inverter-induction motor derive system. A linearized dynamic model of the motor is derived and is converted into the discrete-time model. With the equation, the overall system including the feedback loops is formulated into a single discrete-time state equation. The stability regions are determined at various values of controller gains. The transient responses of the motor speed are simulated by digital computer and are verified by laboratory experiments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1735-1740
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• 2010

The propellant KM10, a single propellant manufactured nitrocellulose, is known to cause natural degradation phenomena at long term storage. The self-life was estimated using generally used high temperature acceleration aging tests to analyze the content of stabilizer and using the Arrhenius equation & Berthelot equation to calculate reaction rate constants. According to the result of this study, self-life of propellant KM10 using the Arrhenius equation & Berthelot equation appear significantly different as 43.73, 16.53years and when compared with the paper of E. R. Bixon, self-life of propellant KM10 predicted using the Arrhenius equation was reasonably determined.

• Structural Engineering and Mechanics
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• v.43 no.5
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• pp.561-582
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• 2012

Despite popularity of FEM in analysis of static and dynamic structural problems and the routine applicability of FE softwares, analytical methods based on simple mathematical relations is still largely sought by many researchers and practicing engineers around the world. Development of such analytical methods for analysis of free vibration of non-prismatic beams is also of primary concern. In this paper a new and simple method is proposed for determination of vibration frequencies of non-prismatic beams under variable axial forces. The governing differential equation is first obtained and, according to a harmonic vibration, is converted into a single variable equation in terms of location. Through repetitive integrations, integral equation for the weak form of governing equation is derived. The integration constants are determined using the boundary conditions applied to the problem. The mode shape functions are approximated by a power series. Substitution of the power series into the integral equation transforms it into a system of linear algebraic equations. Natural frequencies are determined using a non-trivial solution for system of equations. Presented method is formulated for beams having various end conditions and is extended for determination of the buckling load of non-prismatic beams. The efficiency and convergence rate of the current approach are investigated through comparison of the numerical results obtained to those obtained using available finite element software.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.400-412
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• 2022

This paper provides the results of numerical and theoretical predictions of oil outflows from damaged single-hull and double-hull ships.Theoretical equations derived from the unsteady Bernoulli equation and a CFD method for multi-phase flow analysis were used to estimate the oil outflow rate from cargo tank. The predicted oil outflow rate from a single-hull cargo tank damaged due to grounding and collision accidents showed a good agreement with the available experimental results in both numerical and theoretical analyses. However, in the case of the double-hull conditions, the time variation of the amount of water and oil mixture inside the ballast tank predicted by the theoretical equation showed some different behavior from the numerical results. The reason was that the interaction of the oil flow with the water inflow in the ballast tank was not reflected in the theoretical equations. In the problems of the initial pressure condition in the cargo and ballast tanks, the oil outflow and water inflow were delayed at the pressure condition that the tanks were sealed. When the flow interaction between the oil and water in the ballast tank was less complicated, the theoretical and the numerical results showed a good agreement with each other.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.6
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• pp.262-270
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• 2003

In this paper, the characteristics of single-phase line-start permanent magnet synchronous motor driven by constant voltage are analyzed on d-q axis vector diagram and compared with that of current controlled motor. The coupled method of symmetrical coordinates and d-q axis voltage equation are applied to the analysis method like the analysis of single-phase induction motor. From the result of the analysis, it is seen that motors driven by constant voltage source have effects on not only the amplitude of current and torque but also current and current phase angle, so overall characteristics such as power factor and load angle are affected by circuit parameters. For precise analysis and design of single-phase line-start synchronous motor, its characteristics should be analyzed on d-q axis vector plan in consideration of the variation of circuit parameters.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.200-207
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• 2007

Single base propellant using a nitrate ester compound NC decomposes naturally during storage time. Therefore, the research for storage life extension is necessary to single base propellant. In this research, $CaCO_3$ inorganic stabilizer had been added into single base propellants up to 0.3%, and the accelerated aging test of the propellant was started. And then, with applying the Arrhenius equation, the storage life of the test of the propellant was contrasted with that of reference propellant. As a result, the storage life of the propellant containing $CaCO_3$ inorganic stabilizer was about twice longer than the reference propellant.

• Journal of the Korean Society of Child Welfare
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• no.55
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• pp.113-141
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• 2016

The purpose of this study was to examine the mediating roles of children interpersonal relations and mental health in the relationship between parent-child relationships and school life happiness, and the differences between single-parent and two-parent families, using structural equation modeling. Data were obtained from the 2013(second-wave) year of the Korean Educational Longitudinal Study. This study selected 6,643 elementary school 6th-grade students(756 from single-parent families and 5,887 from two-parent families). Data were examined with structural equation modeling and multi-group analysis using AMOS 18.0, and mediating effects were tested using the Sobel test. The results were as follows; First, the single-parent children reported lower levels of interpersonal relations, mental health, and school life happiness than the two-parent children. Second, interpersonal relations and mental health did play a mediating role in the relationship between parent-child relationships and school life happiness. Third, as a result of examining for total effect, the variable that most influenced school life happiness of children was interpersonal relations. Fourth, multi-group analysis did not show a statistically significant difference between single- and two-parent children in structural equation modeling.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.7
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• pp.275-281
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• 2003

$Zn_{0.5}Cd_{0.5}Al_{2}Se_{4}$ and $Zn_{0.5}Cd_{0.5}Al_{2}Se_{4}$:$Co^{2+}$ single crystals were grown by CTR method. The grown single crystals have defect chalcopyrite structure with lattice constant a=5.5966$\AA$, c=10.8042$\AA$ for the pure, a=5.6543$\AA$, c=10.8205$\AA$ for the Co-doped single crystal, respectively. The optical energy band gap was given as indirect band gap. The optical energy band gap was decreased according to add of Co-impurity Temperature dependence of optical energy band gap was fitted well to the Varshni equation. From this relation, we can deduced the entropy, enthalpy and heat capacity. Also, we can observed the Co-impurity optical absorption peaks assigned to the $Co^{2+}$ ion sited at the $T_{d}$ symmetry lattice and we consider that they were attributed to the electron transitions between energy levels of ions.