• Journal of Institute of Control, Robotics and Systems
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• v.7 no.10
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• pp.843-848
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• 2001

Most of gimballed inertial navigation systems(GNIS) are calibrated periodically to maintain their inherent accuracy. The existing calibration techniques using the conventional schuler test with the least square method and the multiposition test take a long time and have some problems in procedures. To solve this problem, calibration method using a linear Kalman filter is proposed by us. In this paper, the calibration method by the change of Schuler period is studied in order to improve the calibration performance of the gimballed INS. First of all, it is shown that the observability of Kalman filter is also enhanced the Schuler period is decreased. Simulation results show that the calibration performance using the present scheme is improved according to the decrease of the Schuler period and the calibration time is shortened extremely, too. And our proposed technique shows desirable estimation performance for the g-sensitive errors of inertial sensors in particular.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.6
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• pp.55-65
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• 2020

The purpose of this study is to empirically analyze the factors that affect start-up activities at the national level. Unlike most existing research about entrepreneurship at the individual level, this empirical analysis makes use of the total early-stage entrepreneurial activity(TEA) index at national level. This was developed by the Global Entrepreneur Monitor (GEM) as the measure for the degree of entrepreneurship of the countries. Based on the previous studies, not only national income level and unemployment rate, but also other factors including the cultural characteristics of the countries were included in our regression model. Using GEM's panel data, we found that the effectiveness of the factors depends on the stage of economic development. In particular, we found 'U-shape' relationship between the level of per capita income and entrepreneurship activity by the panel regression analysis using quadratic function. This analysis result can explicitly confirm what the existing literature have explained descriptively. Furthermore, the governmental support programs are shown to have significantly positive effects on the entrepreneurship or start-up activities in the factor-driven and efficiency-driven economies. On the contrary, those programs were not very helpful in the innovative economies. Lastly, this research suggests that the 'education and training' and the 'entrepreneurial culture' be the supportive norm for new business regardless of the economic development level.