• Journal of Power Electronics
• /
• v.18 no.2
• /
• pp.332-342
• /
• 2018

This paper proposes a parameter design method for multi-element resonant converters (MERCs) with a unique resonant zero point (RZP). This method is mainly composed of four steps. These steps include program filtration, loss comparison, 3D figure fine-tuning and priority compromise. It features easy implementation, effectiveness and universal applicability for almost all of the existing RZP-MERCs. Meanwhile, other design methods are always exclusive for a specific topology. In addition, a novel dual-CTL converter is also proposed here. It belongs to the RZP-MERC family and is designed in detail to explain the process of parameter selection. The performance of the proposed method is verified experimentally on a 500W prototype. The obtained results indicate that with the selected parameters, an extensive dc voltage gain is obtained. It also possesses over-current protection and minimal switching loss. The designed converter achieves high efficiencies among wide load ranges, and the peak efficiency reaches 96.9%.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.127-127
• /
• 2021

In order to estimate parameter uncertainty of hydrological models, the consideration of the likelihood functions which provide reliable parameters of model is necessary. In this study, the Bayesian Markov Chain Monte Carlo (MCMC) method with informal likelihood functions is used to analyze the uncertainty of parameters of the SURR model for estimating the hourly streamflow of Gunnam station of Imjin basin, Korea. Three events were used to calibrate and one event was used to validate the posterior distributions of parameters. Moreover, the performance of four informal likelihood functions (Nash-Sutcliffe efficiency, Normalized absolute error, Index of agreement, and Chiew-McMahon efficiency) on uncertainty of parameter is assessed. The indicators used to assess the uncertainty of the streamflow simulation were P-factor (percentage of observed streamflow included in the uncertainty interval) and R-factor (the average width of the uncertainty interval). The results showed that the sensitivities of parameters strongly depend on the likelihood functions and vary for different likelihood functions. The uncertainty bounds illustrated the slight differences from various likelihood functions. This study confirms the importance of the likelihood function selection in the application of Bayesian MCMC to the uncertainty assessment of the SURR model.

• Transactions of Materials Processing
• /
• v.7 no.5
• /
• pp.450-458
• /
• 1998

The high temperature deformation behavior of Al 5083 alloy has been studied in the temperature range of 350 to 520 ${\circ}C$ and strain rate range of 0.2 to 3.0/sec by torsion test. The strain rate sensitivity(m) of the material was evaluated and used for estabilishing power dissipation maps following the dynamic material model. These maps show the variation of efficiency of power dissipation(${\eta}$=2m/(2m+1)) with temperature and strain rate. Hot restoration of dynamic recrystallization (DRX) was analyzed from the flow curve, deformed microstructure, and processing maps during hot deformation. Also, the effect of deformation strain on the efficiency of power dissipation of the alloy was analysed using the processing maps. Moreover relationship between the hot-ductility and efficiency of power dissipation of the alloy depending on thmperature and strain rate was studied using the Zener-Hollomon parameter(Z=${\varepsilon}$exp(Q/RT) It is found that the maximum efficiency of power dissipation for DRX in Al 5083 alloy is about 74.6 pct at the strain of 0.2. The strain rate and temperature at which the efficiency peak occurred in the DRX domain is found to be ∼0.1/sec and ∼450${\circ}C$ respectively.

• Journal of Advanced Marine Engineering and Technology
• /
• v.22 no.4
• /
• pp.445-450
• /
• 1998

In the present paper the effects of combined heat and mass transfer on the fin efficiency were calculated. Sector method was used for calculating the fin efficiency of the continuous fin. The parameter Lewis No. and C which describe the combined heat and mass transfer is derived by using the heat and mass transfer analogy and effects of Lewis No. and C on the fin efficiencies were calculated.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.9
• /
• pp.1223-1227
• /
• 2013

If the factory test efficiency and field operation efficiency of water turbine are different from each other, issues for efficiency warranty can be raised. So, This paper shows the result for comparative analysis of field operating efficiency vs plant testing efficiency of the water turbine generator installed in agricultural reservoir. The efficiency of the induction generator is analyzed by the change of rotational speed with the parameter obtained by test, the efficiency of water turbine is calculated by the change of head with the design flow. Efficiency deviation of induction generator is lower but the variation of developed power is pretty high near the rated speed and the efficiency variation of water turbine is high by the fluctuation of head for constant flow. It was found that factory test efficiency and total efficiency of water turbine generator calculated according to the rotational speed are very close.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.731-734
• /
• 2002

There have been no obvious design criteria of high efficient displacement pump using a dimensionless parameter which can represent many physical aspect of displacement pump could be very useful to estimate displacement pump performance. Many dimensionless analysis methods have been developed in fluid dynamics, machine design and so on. In this study a new dimensionless parameter is developed for estimate displacement pump performance and efficiency, until now to evaluate the performance of displacement pumps which are widely used in industry field, primarily experimental methods have been used. The dimensionless parameter contains many physical information about pump design. For example, they are the relation between flow rate and power, displacement operation displacement and size, inlet and outlet valve size. And the developed dimensionless functions are induced from numerical method.

• Journal of the Korean Statistical Society
• /
• v.21 no.2
• /
• pp.187-200
• /
• 1992

Samples are often found to be too heterogeneous to be explained by a one-parameter family of models in the sense that the implicit mean-variance relationship in such a family is violated by the data. This phenomenon is often called over-dispersion. The most frequently used method in dealing with over-dispersion is to mix a one-parameter family creating a two parameter marginal mixture family for the data. In this paper, we investigate performance of estimators such as maximum likelihood estimator, method of moment estimator, and maximum quasi-likelihood estimator in negative binomial and beta-binomial distribution. Simulations are done for various mean parameter and dispersion parameter in both distributions, and we conclude that the moment estimators are very superior in the sense of bias and asymptotic relative efficiency.

• Journal of Multimedia Information System
• /
• v.3 no.4
• /
• pp.155-160
• /
• 2016

The Pulse Coupled Neural Network (PCNN) is a kind of neural network models that consists of spiking neurons and local connections. The PCNN was originally proposed as a model that can reproduce the synchronous phenomena of the neurons in the cat visual cortex. Recently, the PCNN has been applied to the various image processing applications, e.g., image segmentation, edge detection, pattern recognition, and so on. The method for the image matching using the PCNN had been proposed as one of the valuable applications of the PCNN. In this method, the Genetic Algorithm is applied to the PCNN parameter learning for the image matching. In this study, we propose the method of the similar image rating using the PCNN. In our method, the Genetic Algorithm based method is applied to the parameter learning of the PCNN. We show the performance of our method by simulations. From the simulation results, we evaluate the efficiency and the general versatility of our parameter learning method.

• Proceedings of the KIEE Conference
• /
• 1999.11c
• /
• pp.549-551
• /
• 1999

Recently, Several type of motors are used more widely in Fan system because of their low cost and high reliability. Therefore, the importance of fault detection and isolation of fan system significantly increases. The motor is a important factor bring out the fan system fault. So the problem of a fault detection for motor based on a parameter identification will be considered in this paper. After an introduction into fault detection with parameter estimation, a mathematical model for motor with special emphasis on motor itself. In the fault detection system, current and motor speed are used as parameter. Finally, simulation results are used to demonstrate the efficiency of the fault detection system.

• International Journal of Quality Innovation
• /
• v.6 no.2
• /
• pp.105-115
• /
• 2005

In recent years, high-speed recording CD-R has already become the mainstream of CD-R market. Therefore, to promote the efficiency of recording CD-R is of significant importance. This study uses Taguchi's parameter design to improve the yield rate for the process of CD-R substrate. We have found 13 three-level controllable factors from the fishbone diagram, repeated 10 times the experiment with the L27(313) orthogonal array, and measured seven quality characteristics. We employ four general methods to find the optimal parameter conditions individually. Then, we perform the confirmation experiment and compare the results. Finally, we obtain the optimal parameter conditions. According to the analysis of benefits, the optimal parameter conditions can reduce the quality loss of CD-R substrate to about 21%. In the future, the results can be extended to other research of DVD-R substrate.