• Journal of The Korean Astronomical Society
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• v.42 no.4
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• pp.71-79
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• 2009

In this paper, statistical distribution functions are developed for distance determination of stellar groups. This method depends on the assumption that absolute magnitudes and apparent magnitudes follow a Gaussian distribution function. Due to the limits of the integrands of the frequency function of apparent and absolute magnitudes, we introduce Case A, B, and C Gaussian distributions. The developed approaches have been implemented to determine distances to some clusters and stellar associations. The comparison with the distances derived by different authors reveals good agreement.

• Korea Trade Review
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• v.46 no.2
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• pp.337-354
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• 2021

Several previous studies have not been able to derive consistent research results on the impact of the level of corruption in local countries on foreign direct investment. Therefore, in order to suggest that this study should consider the relative level of corruption rather than the level of absolute corruption, 1) first, examine the moderating effect of the absolute level of corruption on the determinants of foreign direct investment, and 2) examine the moderating effect of the relative corruption on the determinants of foreign direct investment. This study collected 9-year data from 2012 to 2020 based on the Corruption Perceptions Index (CPI) published by Transparency International. A total of 549 observations (country-year) from 82 countries were sampled and a generalized estimation equation (GEE) analysis was performed. As a result of empirical analysis, it was found that the moderating effect of absolute corruption did not appear, whereas the moderating effect of relative corruption reversed the negative (-) relationship between cultural distance and foreign direct investment into a positive (+) relationship. Based on these empirical results, this study suggest that Korean companies need to consider the relative level of corruption with Korea instead of the absolute level of corruption of the investee when conducting foreign direct investment.

• Journal of Broadcast Engineering
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• v.8 no.4
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• pp.481-491
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• 2003

We present a near-optimal blind decision feedback equalizer (DFE) for Advanced Television Systems Committee digital television (DTV) receivers. By adopting a modified trellis decoder (MTD) with trace back depth of 1 for the decision device In the DFE, we obtain a hardware-efficient near-optimal blind DFE approaching to the optimal DFE which has no error propagation. The MTD uses absolute distance instead of Euclidean distance for computation of a path metric, resulting. In reduced computational complexity. Comparing to the conventional slicer, the MTD shows outstanding performance improvement of decision error probability and is comparable to the original trellis decoder using Euclidean distance. Reducing error propagation in the DFE leads to the improvement of convergence performance in terms of convergence speed and residual error. Simulation results show that the proposed blind DFE performs much better than the blind DFE with the slicer.

• Industrial Engineering and Management Systems
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• v.8 no.4
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• pp.247-256
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• 2009

In mass production industries such as steel making that have large equipment, sudden stops of production process due to machine failure can cause severe problems. To prevent such situations, machine diagnosis techniques play important roles. Many methods have been developed focusing on this subject. In this paper, we propose a method for the early detection of the failure on rotating machine, which is the most common theme in the machine failure detection field. A simplified method of calculating autocorrelation function is introduced and is utilized for ARMA model identification. Furthermore, an absolute deterioration factor such as Bicoherence is introduced. Machine diagnosis can be executed by this simplified calculation method of system parameter distance with weight. Proposed method proved to be a practical index for machine diagnosis by numerical examples.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.25-26
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• 2006

The method measuring the absolute position of a point diffraction source emitting a spherical wavefront in three-dimension is proposed. Two-dimensional interference of spherical wavefronts is used to overcome ambiguity of phase order. The spherical wavefront is explicated by Taylor series expansion, from which a radius of curvature of a spherical wavefront and its center position in three-dimension are obtainable. The spherical wavefront is reconstructed by a modified lateral shearing interferometer, which uses single-mode fiber as a point diffraction source.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.843-844
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• 2011

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.10
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• pp.1448-1451
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• 2021

In this paper, 3D range sensor is applied to the sensor-based widerange microphone system for lectures. Since the 2D range sensor measures the shortest distance of the speaker, an error occurs and the performance is degraded. The 3D sensor provides a 160×60 distance image so that the position of the speaker can be obtained with accuracy. We propose a method for obtaining the distance per pixel required to determine the absolute position of the speaker from the distance image. The proposed array microphone system using the 3D sensor shows the improvement of 0.8~1.5dB compared to the previous works using 2D sensor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.139-140
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.619-620
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.511-512
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• 2009