• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1638-1643
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• 2010

HVDC is better economic method than HVAC in case of long distance transmission and it is possible to interconnect transmission lines regardless of difference of power frequency. The electrical environment problems of HVDC overhead transmission line are electric field, charged voltage, ion current and so on. For biopolar HVDC lines, most of the ions are directed toward the opposite polarity conductor, but a significant fraction is also directed toward the ground. These problems are major factor to design configuration of HVDC overhead transmission line. Therefore, It is necessary to test an environmental characteristics of HVDC overhead transmission line. In this paper, to assess the ion characteristic of HVDC transmission line, continuous measurements have been done on the biopolar single circuit line with ACSR 480mm2-6 bundle conductors of Gochang HVDC Test line. And then the ion characteristics were analyzed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.2
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• pp.281-287
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• 1997

In the conventional inverse modeling method for on-line modeling of the secondary path transfer function, the signal to noise ratio between the arbitrary random signal and the plant noise have to keep at -10 - -20 dB. For these reasons, the modeling can't be exactly implemented by the conventional method alone and the convergence time for modeling becomes too long. In this study, by combining the conventional inverse modeling method with an adaptive line enhancer, or with an adaptive noise canceller, a rigorous transfer functions of secondary path modeling and the control of a primary noise have been implemented simultaneously.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.760-763
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• 1997

Using telesensor programming method, we control the space robot which has two 2-DOF manipulators. To make this control system, we devide total works by elemental operation. And we make a simulation system that can simulate sensors and robot. In the simulation system, we make a sensor data and robot paths by "Teaching by showing" method. And using these data, we control the real space robot. This off-line method can solve long time delay problem in teleoperation.operation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.12 no.1
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• pp.13-17
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• 1976

1. Around the Jeju Island, 214 fish species are described by some authors, of which 53 species are regarded as major fishes for the object of commercial fishing. 2. Major fishing method around the Jeju Island are scoop net for anchovy, gill net for mackerels, long line for sea breams. For large pelagic fishes such as yellow tail, tolling method are expected.

• Journal of Ocean Engineering and Technology
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• v.21 no.4
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• pp.15-20
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• 2007

The harbor siltation by longshore sediment transports has become a serious problem on the East Coast of Korea. A reasonable prediction of the longshore sediment rate is important to approach the siltation problem effectively. In the recently developed 1-line model, the empirical constants of the sediment transport formula, which include the absolute quantity of sediment transport rate and the spatial distribution of breaking wave height by wave deformation, are treated as calibration parameters. Since these constants should be determined by the very long-term shoreline data, the longshore sediment rates are much more reasonable values. The method was applied to Hupo Beach, which has experienced heavy siltation. The authors also discuss long-term shoreline change using aerial photos and the observed wave-induced current patterns. According to the result, the SW-direction sediment transport rate was $146,892m^3/year$, and the NE direction was $2,694,450m^3/year$ at Hupo Beach for the last 11 years. The siltation in Hupo Harbor might be affected by the NE-direction sediment transport from Hupo Beach.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1376-1385
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• 2017

This paper proposes a method for estimating the expected frequency of voltage swells caused by asymmetrical faults in a power system. Although voltage swell is less common than voltage sag, repeated swells can have severe destructive impact on sensitive equipment. It is essential to understand system performance related to voltage swells for finding optimal countermeasures. An expected swell frequency at a sensitive load terminal can be estimated based on the concept of an area of vulnerability (AOV) and long-term system fault data. This paper describes an effective method for calculating an AOV to voltage swells. Interval estimation for an expected swell frequency is also presented for effective understanding of system performance. The proposed method provides long-term performance evaluation of the frequency and degree of voltage swell occurrences.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.193-196
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• 2004

Numerical optimization method of long endurance airfoil has been performed with a RSM(Response Surface Method) for smart UAV wing design. For the base line airfoil, NACA 64621 airfoil was selected and optimized to satisfy long endurance condition for smart UAV Aerodynamic coefficients required for RSM are obtained by using 2-D Navier-Stokes solver with Spalart-Allmaras turbulence model. The optimized airfoil showed increased maximum lift and endurance factors together with reasonable thickness ratio.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.566-571
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• 2009

A calibration method for multiple sets of stereo vision cameras is proposed. To measure the three-dimensional shape of a very long object, measuring the object at different viewpoints and registration of the data are necessary. In this study, two lasers beams generate two strings of calibration targets, which form straight lines in the world coordinate system. An evaluation function is defined to calculate the sum of the squares of the distances between each transformed target and the fitted line representing the laser beam to each target, and the distances between points appearing in the data sets of two adjacent viewpoints. The calculation process for the approximation method based on data linearity is presented. The experimental results show the effectiveness of the method.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.11 s.176
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• pp.82-90
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• 2005

Recently, the in-line vision inspection has become the subject of growing research area in the visual control systems and robotic intelligent fields that are required exact three-dimensional pose. The objective of this article is to study the pc based in line visual inspection with the hand-eye structure. This paper suggests three dimensional structured light measuring principle and design method of laser sensor header. The hand-eye laser sensor have been studied for a long time. However, it is very difficult to perform kinematical analysis between laser sensor and robot because the complicated mathematical process are needed for the real environments. In this problem, this paper will propose auto-calibration concept. The detail process of this methodology will be described. A new thinning algorithm and constrained hough transform method is also explained in this paper. Consequently, the developed in-line inspection module demonstrate the successful operation with hole, gap, width or V edge.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.527-528
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• 2007

A field-oriented UHF system for on-line PD monitoring of transformers is designed, which has been installed inside the oil tank of a 220kV transformer in a substation. This system has successfully captured long intermittent discharge signals that hadn't been detected through conventional techniques, and solved the problem successfully. The results demonstrate that UHF technique has great advantages for on-line PD monitoring of transformers. By adopting the peak detection technique, it becomes easy and effective for the transplantation of the phase-resolved pattern recognition technique from conventional method to UHF method, and then to realize continuous on-line monitoring, source characterization and trending analysis.