• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.28 no.11
• /
• pp.894-901
• /
• 2017

In the existence of motion, azimuth phase error due to accuracy limitation of GPS/IMU and system delay is unavoidable and it is essential to apply autofocus to estimate and compensate the azimuth phase error. In this paper, autofocus algorithm using MWLS(Modified WLS) is proposed. It shows the robust performance compared with original WLS using new target selection/sorting metric and iterative azimuth phase estimation technique. SAR raw data obtained in a captive flight test is used to validate the performance of the proposed algorithm.

• International Area Studies Review
• /
• v.12 no.3
• /
• pp.171-194
• /
• 2008

This paper analysis the long-run demand for monetary indicator M2 and Liquidity indicator L in Korea in the period from 1980:1 to 2006:3 by cointegration and error correction models. The empirical evidence that M2, L in Korea is meaningfully cointegrated with income, interest rate, exchange rate, inflation uncertainty, real effective exchange rate, exchange rate uncertainty and LIBOR, thus showing the existence of long-run demand function under open-economy framework.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.5
• /
• pp.580-586
• /
• 2008

The prediction of a system coverage is required to install or operate a base station of the differential global positioning system(DGPS). However, the predicted results differ from the measured results when those are analyzed using ITU-R effective ground conductivity values. Thus, in this paper, the coverages of DGPS reference stations are analyzed using the modified effective ground conductivity values. The modified effective ground conductivity is based on the effective ground conductivity of ITU-R and modified to minimize the error between the measured electric fields and the predicted electric fields by using a statistical method. Then, the DGPS system coverages are analyzed by using the modified effective ground conductivity values, and the system stability is verified with a various analysis.

• Journal of Korea Water Resources Association
• /
• v.35 no.3
• /
• pp.307-319
• /
• 2002

This study used the WGR model to generate the rainfall input and the modified Clark method to estimate the runoff with the aim of investigating how the errors from the areal average rainfall propagates to runoff estimates. This was done for several cases of raingauge density and also by considering several storm directions. Summarizing the study results are as follows. (1) Rainfall and runoff errors decrease exponentially as the raingauge density increases. However, the error stagnates after a threshold density of raingauges. (2) Rainfall errors more affect to runoff estimates when the density of raingauges is relatively low. Generally, the ratio between estimation errors of rainfall and runoff volumes was found much less than one, which indicates that there is a smoothing effect of the basin. However, the ratio between estimation errors of rainfall to peak flow becomes greater than one to indicate the amplification of rainfall effect to peak flow. (3) For the study basin in this studs no significant effect of storm direction could be found. However, the runoff error becomes higher when the storm and drainage directions are identical. Also, the error was found higher for the peak flow than for the overall runoff hydrograph.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.20 no.5
• /
• pp.533-541
• /
• 2007

The Zienkiewicz-Zhu(Z/Z) error estimate is slightly modified for the hierarchical p-refinement, and is then applied to L-shaped plates subjected to bending to demonstrate its effectiveness. An adaptive procedure in finite element analysis is presented by p-refinement of meshes in conjunction with a posteriori error estimator that is based on the superconvergent patch recovery(SPR) technique. The modified Z/Z error estimate p-refinement is different from the conventional approach because the high order shape functions based on integrals of Legendre polynomials are used to interpolate displacements within an element, on the other hand, the same order of basis function based on Pascal's triangle tree is also used to interpolate recovered stresses. The least-square method is used to fit a polynomial to the stresses computed at the sampling points. The strategy of finding a nearly optimal distribution of polynomial degrees on a fixed finite element mesh is discussed such that a particular element has to be refined automatically to obtain an acceptable level of accuracy by increasing p-levels non-uniformly or selectively. It is noted that the error decreases rapidly with an increase in the number of degrees of freedom and the sequences of p-distributions obtained by the proposed error indicator closely follow the optimal trajectory.

• The KIPS Transactions:PartB
• /
• v.11B no.2
• /
• pp.141-148
• /
• 2004

The ground positions and elevations information called DEMs(Digital Elevation Models) which are extracted from the stereo aerial photographs and/or satellite images using image matching method have the natural errors caused by variant environments. This study suggests the method to evaluate DEMs using correlation values between the reference and the target DEMs. This would be strongly helpful for experts to correct these errors. To evaluate the whole area of DEMs in the horizontal and vertical errors, the target cell is matched for each reference cell using the correlation values of these two cells. When the target cell is matched for each reference cell, horizontal and vertical error was calculated so as to help experts to recognize a certain area of DEMs which should be corrected and edited. If the correlation value is low and tile difference in height is high, the target cell will be candidated as changed or corrupted cell. When the area is clustered with those candidated cells, that area will be regarded as changed or corrupted area to be corrected and edited. Using this method, the evaluation for all DEM cells is practicable, the horizontal errors as well as vertical errors is calculable and the changed or corrupted area can be detected more efficiently.

• International Commerce and Information Review
• /
• v.14 no.3
• /
• pp.307-322
• /
• 2012

The purpose of this paper is to examine determinants of export to the East Asia region, using panel unit root, panel cointegration framework, panel VECM (vector error correction model), panel FMOLS (fully modified OLS). Different panel unit root tests confirm that the data series are integrated processes with unit roots. When applying cointegration tests to long-run effect for aggregate panel data, a primary concern is to construct the estimators in a way that does not constrain the transitional dynamics to be similar among different countries of the panel. The regression equations are estimated by various panel cointegration estimators. The panel data causality results reveal that exchange rates has unidirectional effects on export and GDP, and there exists bidirectional causality between export and GDP. Also, the results from the panel FMOLS tests overwhelmingly reject the null hypothesis of zero coefficient. The panel cointegrating vectors show that the export has positive relationship with the GDP and ODI (overseas direct investment).

• Culinary science and hospitality research
• /
• v.23 no.2
• /
• pp.126-134
• /
• 2017

The purpose of this paper was to examine the dynamics of the price discovery function between lean hog futures and spot markets using the vector error correction model (VECM). The researcher also investigated the existence of the long-run equilibrium relationship between the lean hog futures and spot markets. Daily time series data of lean hog futures and spot observed in the Korean market during the period from 5 Jan. 2011 to 28 Dec. 2012 were analyzed. To examine the price discovery, this study employed the Gonzalo and Granger's (1995) information ratio and Hasbrock's (1995) information ratio measurement method. The significant findings of the study are summarized as follows. First, lean hog futures and spot market are significantly correlated. Secondly, the lean hog future market plays a more dominant role in price discovery than the spot market. Finally, price discovery measures based on the VECM suggested that the lean hog future market plays a more dominant role in price discovery than the lean hog spot market. This is the important systematic empirical work to find the relationship between the lean hog future and spot market.

• Environmental and Resource Economics Review
• /
• v.24 no.4
• /
• pp.709-725
• /
• 2015

This study is to analyse the relationship between the price and the supply in the farming Olive Flounder's production area market. The data used in this study correspond to daily price and supply quantity covering time period from January 1, 2007 to June 30. 2013. The analysis methods of cointegration and vector error correction model are employed. The empirical results of this study are summarized as follows: First, the price and the supply follow random walks and they are integrated of order 1. Second, the price and the supply are cointegrated. Third, vector error correction model suggests that the relationship between the price change ration and the supply quantity change ratio has negative and feedback effect exists in the long-run, but the disequilibrium between the price and the supply is corrected by the supply quantity. Finally, vector error correction model suggests that the supply quantity leads the price in the short-run. This indicates that the decrease(increase) of the supply quantity results in the increase(decrease) of the price.

• Environmental and Resource Economics Review
• /
• v.24 no.4
• /
• pp.679-708
• /
• 2015

Almost all of natural gas demand in Korea is currently met by overseas LNG imports. More than 80% of LNG is imported through the mid to long-term contracts with oil-linked pricing. Despite LNG price estimation provides valuable information with various interested parties, an empirical study as well as an econometric model on LNG price hasn't yet been available in Korea. This paper therefore, aims at analyzing not only whether the long-run equilibrium relationship between oil prices and Korean LNG prices exists but also whether structural change occurred in such relationship. Further, it aims at building a conditional VECM taking account of a structural change. According to the final model, an oil price shock is passed through to the LNG prices in nonlinear and different manner from the past.