• Journal of Environmental Science International
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• v.7 no.3
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• pp.335-348
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• 1998

The intensive meteorological observations including pibal balloon at Ungcheon, airsonde and 10m meteorological tower observations at Gulup-Do, where are located In the western coastal region, are taken to Investigate the characteristics of the upper and lower atmospheric structure and the local circulation pattern during the period of 17 to 22 September 1996. The diurnal variations of weather elements(i.e. air temperature, humidity, pressure, and Und speeds at Gulup-Do are analyzed and discussed with those at four inland meteorological stations. The vertical profiles of wind vector, ortho- gonality(Ω), and shear obtained from the pibal obsenrations are also presented to examine the change of wand structure according to the synoptic-scale pressure system's movement. The diurnal temperature changes at Gulup-Do are more sensitive than that of Inland meteorological stations In case of the mow of southwesterlies but are not dominant due to the ocean effect under the Influence of relatively cold northerlies. A well defined mixed layer Is developed from the 500m to the maximum 1700m with a significant capping Inversion layer on the top of it. It can be found from the vertical profiles of wind vector that the wind become generally strong at the interface heights between cloud lay- ers and non-cloud layers. The maximum Und shear Is appeared at the bel각t where the varlauon of wand direction Induced by the passage of synoptic-scale pressure system Is accompanied with the In- crease of Und speed. Based on the wind orthogonality, the change of wind direction with height is more complicated In cloudy day than In clear day. In case of a fair weather, the change of wand direction is showed to be at around 2km.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.144-149
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• 2012

The transfer matrix method is used to determine the dynamic characteristics(natural frequencies and mode shapes) by rotational speed of wind turbine blade. The problems treated on this study is coupled flapwise bending and chordwise bending of pre-twisted nonuniform wind turbine blade. The orthogonality relations that exist between the vibrational modes is derived and the algorithm for determination of the natural vibrational characteristics is suggested.

• Wind and Structures
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• v.3 no.4
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• pp.221-241
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• 2000

Structural dynamics usually applies modal transformation rules aimed at de-coupling and/or minimizing the equations of motion. Proper orthogonal decomposition provides mathematical and conceptual tools to define suitable transformed spaces where a multi-variate and/or multi-dimensional random process is represented as a linear combination of one-variate and one-dimensional uncorrelated processes. Double modal transformation is the joint application of modal analysis and proper orthogonal decomposition applied to the loading process. By adopting this method the structural response is expressed as a double series expansion in which structural and loading mode contributions are superimposed. The simultaneous use of the structural modal truncation, the loading modal truncation and the cross-modal orthogonality property leads to efficient solutions that take into account only a few structural and loading modes. In addition the physical mechanisms of the dynamic response are clarified and interpreted.