• Journal of applied mathematics & informatics
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• v.9 no.2
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• pp.593-605
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• 2002

Explicit hounds are obtained for the perturbed, or corrected, trapezoidal and midpoint rules in terms of the Lebesque norms of the second derivative of the function. It is demonstrated that the bounds obtained are the same for both rules although the perturbation or the correction term is different.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2018.06a
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• pp.120-120
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• 2018

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2017.11a
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• pp.71-71
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• 2017

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.453-459
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• 2021

The system marginal price of electricity is the amount paid to all the generating units, which is an important decision-making factor for the construction and maintenance of an electrical power unit. In this paper, we suggest a long-term forecasting model for calculating the system marginal price based on prices of natural gas and oil. As most variables used in the analysis are nonstationary time series, the long run relationship among the variables should be examined by cointegration tests. The forecasting model is similar to an error correction model which consists of a long run cointegrating equation and another equation for short run dynamics. To mitigate the robustness issue arising from the relatively small data sample, this study employs various testing and estimating methods. Compared to previous studies, this paper considers multiple fuel prices in the forecasting model of system marginal price, and provides greater emphasis on the robustness of analysis. As none of the cointegrating relations associated with system marginal price, natural gas price and oil price are excluded, three error correction models are estimated. Considering the root mean squared error and mean absolute error, the model based on the cointegrating relation between system marginal price and natural gas price performs best in the out-of-sample forecast.

• Journal of the Korean Regional Science Association
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• v.33 no.3
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• pp.3-19
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• 2017

The purpose of this paper is to analyze the impacts of regional industrial diversity on regional business cycle response to national volatility. We employed mean group and pooled mean group estimators of panel vector error-correction models in order to control unobserved heterogeneity of the port cities, such as Pusan, Ulsan and Incheon. The results show that in various industrial regions, short-term fluctuations in the unemployment rate are small compared to other regions. On the contrary, long-term volatility of manufacturing production index is low in those regions.

• The Journal of Fisheries Business Administration
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• v.32 no.1
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• pp.1-14
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• 2001

The research on the price-volume relation in the market is very important because it examines into regular phenomenon revealed by market participants including producers and middlemen. The purpose of this study is to investigate the relationship between price and trading volume in the oyster producing market. In order to accomplish the purpose of this study, the contents of empirical analysis include the time series properties of price and trading volume, the short-term and long-term relationships between price and trading volume, and the determinants of trading volume. The data used in this study correspond to daily price and trading volume covering the time period from January 1998 to April 2001. The empirical results can be summarized as follows : First, price and trading volume follow random walks and they are integrated of order 1. The first difference is necessary for satisfying the stationary conditions. Second, price and trading volume are cointegrated. This long-run relationship is stronger from trading volume to price. Third, error correction model suggests that feedback effect exists in the long-run and that price tends to lead trading volume by about five days in the short run, that is, to be required period by digging, conveying, and peeling oystershell for selling oyster. Fourth, price and price volatility is a determinant of trading volume. In particular, trading volume is a negative function of price. It is believed that the conclusion drawn from this study would provide a useful standard for the policy makers in charge of reducing the oyster price volatility risk caused by trading volume(selling quantities).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.4 s.175
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• pp.1065-1074
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• 2000

A robust nonlinear $H_2$/$H_{\infty}$ control method for a parallel inverted pendulum with structured perturbation and dry friction is proposed. By the random input describing function techniques, the nonlinear dry friction is approximated into the quasi-linear system. Introducing the quadratic robustness theorem, the robust $H_2$/$H_{\infty}$ control system is constructed for the quasi-linear perturbed system. But it is difficult to design a controller due to the nonlinear correction term in Riccati equation. With some transformations on the Riccati equation containing nonlinear correction term, the design of the robust nonlinear controller can be done easily. Hence when the stiffness and mass of the parallel inverted pendulum vary in certain ranges, the proposed control scheme has the robustness for both the structured perturbation and dry friction. The results of computer simulation show the effectiveness of our proposed control method.

• Journal of Chest Surgery
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• v.28 no.11
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• pp.1038-1044
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• 1995

We have been used cryopreserved homograft valves for right ventricular outflow tract[RVOT reconstruction since November 1993. The homograft valves were harvested from the hearts of brain dead patients or hearts of transplant recipients. There were 12 male and 10 female patients. Their ages ranged from 5 months to 13 years[mean age,39.2 $\pm$ 37.4 months and the weight ranged from 5 to 48kg [mean weight, 13.7$\pm$ 9. l kg . The diagnoses included pulmonary atresia with ventricular septal defect [n=14 , tetralogy of Fallot[n=4 , truncus arteriosus[n=3 , and double outlet right ventricle with pulmonic stenosis[n=l .Monocuspid homograft patches were used for RVOT widening or REV[reparation l`etage ventriculaire operations in 4 patients. We also used homograft as valved conduits for RVOT reconstruction in 17 patients and left ventricular outflow tract reconstruction in anatomically corrected transposition in 1 patient. Among them size-reducing technique [converting a tricuspid valved conduit into a bicuspid valved conduit were applied to six patients for the correction of size mismatching. The mean follow-up period was 10.6 $\pm$ 5.4 months. There was one operative death[4.5% due to bleeding and one reoperation for removal of vegetation on the homograft leaflet. Postoperative echocardiography documented no significant homograft insufficiency and RVOT obstructions.In short-term, the homograft valves provide excellent hemodynamic characteristics, even though further studies are necessary to evaluate the long-term results.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.128-141
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• 1998

We propose the robust nonlinear controller design methodology for the multivariable system which has hard nonlinearities (Coulomb friction, dead-zone, etc) and the structured real parameter uncertainty. The hard nonlinearity can be linearized by the RIDF technique and structured real parameter uncertainty can be modelled as the sense of Peterson-Hollot's quadratic Lyapunov bound. For this system, we apply the robust QLQG/H$_{\infty}$ control and then can obtain four Riccati equations. Because of the system's nonlinearity, however, one Riccati equation contains the nonlinear correction term that is very difficult to solve numerically, In order to treat this problem, using some transformations to Riccati equations, the nonlinear correction term can be eliminated. Then, only two Riccati equations need to design a controller. Finally, the robust nonlinear controller is synthesized via IRIDF techniques. To test this proposed control method, we consider the direct-drive robot manipulator system that has Coulomb frictions and varying inertia.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4_1
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• pp.121-128
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• 1992

This study aims to define the algorithm for self-calibration bundle adjustment with additional parameters, which is fit for the correction systematic errors in the SPOT satellite imagery, and to present a suitable term of additional parameters for the data form of SPOT satellite imagrery. As a result, an algorithm of self-calibration bundle adjustment for SPOT satellite imagery was settles, and the computer program was developed. Also, the suitable term of additional parameters to correct the systematic errors for each data form was defined through examination for determination effect of additional parameters and significance test. The algorithm of self-calibration bundle adjustment for SPOT satellite imagery according to this study could improve the accuracy of positioning.