• Atmosphere
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• v.22 no.2
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• pp.259-265
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• 2012

This study investigates the reason why the barotropic vorticity structure prevails vertically in response to the enhanced convection associated with the boreal summer intraseasonal oscillation over the central Indian Ocean. The relative vorticity tendency analysis for a 2.5-layer simplified model demonstrates that the barotopic vorticity structure is predominant due to the following two factors: 1) vertical easterly shear on the meridional gradient of barotropic divergence (which induces generation of barotropic vorticity twice larger than that of baroclinic vorticity); and 2) vertical easterly shear on the meridional gradient of baroclinic divergence (which appears only in relation to the generation of barotropic vorticity). The percentage of contribution by each term to barotropic and baroclinic vorticity tendency equations is presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.387-392
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• 2002

A portable mould oscillation analyzer with an integrated computer, developed by POSCO, records the movement of the mould in every spatial direction. The system uses the gap sensors to measure the mould movement (displacement) in two horizontal directions according to the mould narrow and broad faces and the vertical strokes in the four corners of mould. The gap sensor is a non-contacting minute displacement-measuring device using the principle of high frequency eddy current loss. The mould oscillation diagnostic system integrates the gap sensors, their converters and the industrial portable computer with plug-in data acquisition boards. In an own expert module, which is included in the diagnosis program, one can obtain much information about the mould oscillation equipment.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.10a
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• pp.136-136
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• 1998

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.447-450
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• 2009

In order to protect conductors from oscillations or vibrations due to winds, spacer dampers are installed on overhead transmission lines. Generally the spacer damper clamp can move slightly according to oscillation directions, namely in longitudinal, vertical & horizontal directions. This is for reducing fatigue phenomena of the conductor. But the high longitudinal- displacement of the clamp raises a doubt for its necessity. Then this paper carried out oscillation tests by using 4 bundle test lines, to know the relation between longitudinal displacement and oscillation. and suggests design necessity of the longitudinal articulation part for spacer damper clamps.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.12
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• pp.3960-3969
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• 1996

A fluid flow inside a circular cylinder subject to horizontal and circular oscillation is analyzed theoretically. Under the assumption of small-amplitude oscillation, the governing equations take linear forms. The velocity field is obtained in terms of the first kind of Bessel function of order 1. It was found that a particle describes an orbit close to a circle in the central region and an arc near the side wall. We also obtained the Stokes' drift velocity induced by the traveling wave along the circumferential direction. The Eulerian streaming velocities at the edge of the bottom and side boundary layers were also obtained. It was shown that the vertical component of the steady streaming velocity on the side wall is almost proportional to the amplitude of the free surface motion.

• Economic and Environmental Geology
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• v.32 no.6
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• pp.653-660
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• 1999

Any mechanical system has a natural oscillation which can be excited, and the earth is no exception. The earth can oscillate in an indefinite number of normal modes of oscillation, rather like a giant bell. The various free modes are generally sparated into two categoridal modes and toroidal modes. Clearly the toroidal modes will produce no perturvation of the gravity field and no vertical acceleration on the surface of the earth. Hence only spheroidal modes can be detected with a gravimeter. EarthTide gravimeter was installed at AIMST in order to observe free modes of the earth. Eight major earthquakes including chinese earthquake (magnitude 7.3) with free oscillations of the earth are observed during one year (1998. 8. 1∼1999.7.31). And then the earth tides components were eilminated from earthquake records using a numerical Butterworth highpass filter. Spectral analysis of gravity readings repersent that 48 observations of shheroidal modes. The relationships between instrumental observations and theoretical predictions based on the Gutenberg earth model agree well those resulting from free oscillation in Korea.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.5 no.4
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• pp.285-294
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• 1993

An oscillatory motion of natural convection in a two-dimensional square enclosure fitted with a horizontal partition is investigated numerically. The enclosure was composed of the lower hot and the upper cold horizontal walls and the adiabatic vertical walls, and a partition was positioned perpendicularly at the mid-height of one vertical insulated wall. The governing equations are solved by using the finite element method with Galerkin method. The computations were carried out with the variations of the partition length and Rayleigh number based on the temperature difference between two horizontal walls and the enclosure height with water(Pr=4.95). As the results, an oscillatory motion of natural convection has perfectly shown the periodicity with the decrease of Rayleigh number, and the stability was reduced to a chaotic state with the increase of Rayleigh number. The period of oscillation gets shorten with the decrease of the partition length and the increase of Rayleigh number. The frequency of oscillation obtained by the variations of stream function is more similar to the experimental results than that of the average Nusselt number. The stability of oscillation grows worse with the increase of Rayleigh number. The transition Rayleigh number for the chaos is gradually decreased with the increase of the partition length.

• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.124-131
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• 1999

In this paper, we show the numerical and experimental results of two-dimensional fluid motions inside a rectangular container with a vertical plate subjected to a background rotation added by a rotational oscillation. In the PIV experiment we apply a new algorithm, NTSS, to the velocity calculation. In the numerical computation, the linear Ekman-pumping model was used to take the bottom friction effect into account. It was found that it showed good agreement with the experimental results at low ${\epsilon}$ number.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.3
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• pp.228-232
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• 2005

This paper presents the efforts of the studies for improvement of spin characteristics of KTX-1 #02 through rotary balance test, forced oscillation test and spin mode analysis. During the full scale development design stage, we had fullfilled a lot of spin flight test, spin mode analysis. Based on all of the efforts, KTX-1 had been developed as a successful trainer with excellent spin characteristics.

• Korean Journal of Crystallography
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• v.4 no.2
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• pp.49-53
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• 1993

A converuent crystal orientation method for oscillation shot ograchy using de Jong Boumancamera is presented The method involves the measuremint of the deviations of resection spots of Oth layer from the equator These deviations are added or subtracted to give the horizontal and vertical arc corrections.