• Journal of The Korean Astronomical Society
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• v.36 no.spc1
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• pp.101-107
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• 2003

The magnetosphere is often perturbed by impulsive input such as interplanetary shocks and solar wind discontinuities. We study how these initial perturbations are propagating within the magnetosphere over various latitude regions by adopting a three-dimensional numerical dipole model. We examine the wave propagation on a meridional plane in a time-dependent manner and compare the numerical results with multi-satellite and ground observations. The dipole model is used to represent the plasmasphere and magnetosphere with a realistic Alfven speed profile. It is found that the effects of refraction, which result from magnetic field curvature and inhomogeneous Alfven speed, are' found to become important near the plasmapause. Our results show that, when the disturbances are assumed at the subsolar point of the dayside magnetosphere, the travel time becomes smaller to the polar ionosphere compared to the equatorial ionosphere.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.181-188
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• 2000

Input shaping is a method fur reducing residual vibration. Vibration is eliminated by convolving an input shaper, which is a sequence of impulses, with the desired system command. It has been applied to robot with a flexible manipulator. But it can be applied to the reduction of residual vibration far overhead crane. In this paper, input shaping shows good performance for anti-sway of overhead crane. In the z-domain, we designed an input shaper and calculated the sensitivity of it. If sensitivity is calculated in the z-domain, the shapes of sensitivity curves are expected easily. Accordingly, it is easy to design an input shaper in the z-domain. We compared the response of a system with shaper to it without that. Also, we compared El shaper to ZV shaper in view of robustness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1228-1231
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• 2004

We analyzed the impulse on 24 sensors location under the foot using the Parotec system for the investigation of the relationship between the shoe type and the foot pathologies. Total 7 kinds of shoes, i.e. sport shoe, high heel shoes (5cm heel, 8cm heel, 13cm heel), platform shoe, inline skate, and heelys were evaluated for 20 normal subjects. Compared with the impulse distribution of the sport shoe, greater impulses were shown at the 1$^{st}$ phalange and the 1$^{st}$ metatarsal-phalangeal head in high-heel shoes, lateral tarsal bone and medial metatarsal bone in platform shoe, medial tarsal bone in inline-skate, and medial tarsal bone and 1st phalange in heelys shoe. The result of this study is expected to provide useful information about the relationship between the shoe type and the foot pathologies.ies.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.37-37
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• 2003

Electron whistlers frequently excite proton whistlers. The proton whistlers appear on the dynamic spectrum as rising tones, which start after the reception of a short electron whistler, asymptotically approaching the local proton gyro-frequency. The proton whistlers are dispersed forms of lightning impulses and their dispersion can be explained by the effects of heavy ions such as H+ and He+ on the propagation of an electromagnetic wave in the ionosphere. In the ionosphere, a right-handed circularly-polarized electron whistler becomes coupled to a left-handed circularly-polarized proton whistler when the frequency becomes close to a cross-over frequency. By adopting the multi-fluid numerical wave model, we examine how the mode coupling varies as the ion composition changes along altitude in the mid-latitude ionosphere. The time histories and dynamic spectra of electric fields are presented. In addition, we compare our results with the previous theoretical and observational studies.

• Advances in Computational Design
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• v.1 no.4
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• pp.357-370
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• 2016

This paper aims to examine the dynamic response of a newly designed ultrasonic motor under half-sine shock impulses. Impact shock was applied to the motor along x, y or z axis respectively with different pulse widths to check the sensitivity of the motor to the shocks in different directions. Finite Element Analysis (FEA) with the ANSYS software was conducted to obtain the relative displacement of a key point of the motor. Numerical results show that the maximum relative displacement is of micro meter level and the maximum stress is five orders smaller than the Young's modulus of the piezo material, which proves the robustness of the motor.

• Journal of East-West Nursing Research
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• v.17 no.2
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• pp.125-131
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• 2011

Purpose: In an attempt to investigate causes of runaway impulse in male and female students with runaway impulse experience in high schools, this study was carried out. Methods: The subjects were 195 high school students in Gyeonggi and Incheon area. The data were collected by using the questionnaires. Results: To both male and female students, the main causes of runaway impulse were 'conflicts with parents', 'interference and excessive expectations of parents' and 'burden of study and grades'. In cases of youth with runaway experience by runaway impulse, the major causes of runaway impulse were 'want to have fun with friends' and 'conflicts with parents'. Also shelter and economic difficulties were obstacles that prevent a runaway despite runaway impulse to both male and female students. But in female, the fear and anxiety about runaway were higher barriers than those of male. Conclusion: From the above results, major causes of runaway impulses were relationships with parents, and burden of study. And barriers to prevent a runaway were shelter, economic difficulties to both male and female students.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1764-1771
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• 2002

The latch needle cam system of circular knitting machines is analysed using multibody dynamics. A formulation is made to obtain the vertical stiffness between the needle and the cam. By implementing this formulation into the data of the multibody dynamics program, the motion of the needle is described and the forces and impulses between the needle and the cam are obtained.

• Nuclear Engineering and Technology
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• v.32 no.4
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• pp.299-308
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• 2000

A safety assessment of reactor vessel lower head integrity under in-vessel vapor explosion loads has been performed. The core melt relocation parameters were chosen within the ranges of physically realizable bounds. The premixing and explosion calculations were performed using TRACER-II code. Using the calculated explosion pressures imposed on the lower head inner wall, strain calculations were peformed using ANSYS code. Then, the calculated strain results and the established failure criteria were used in determining the failure probability of the lower head, In the explosion analyses, it is shown that the explosion impulses are not altered significantly by the uncertain parameters of triggering location and time, fuel and vapor volume fractions in uniform premixture bounding calculations. Strain analyses show that the vapor explosion-induced lower head failure is not possible under the present framework of assessment. The result of static analysis using the conservative explosion-end pressure of 50 MPa also supports the conclusion. It is recommended, however, that an assessment of fracture mechanics for preexisting cracks be also considered to obtain a more concrete conclusion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1127-1132
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• 2000

Impulsive acoustic and vibration signals within rotating machinery are often induced by irregular impacting. The detection of these impulses can be useful for fault diagnosis purposes. Recently there has been an increasing trend towards the use of higher order statistics for fault detection within mechanical systems based on the observation that impulsive signals tend to increase the kurtosis values. This paper considers the use of the third and fourth order Wigner moment spectra, called the Wigner bi- and tri- spectra receptively, for analysing such signals. Expressions for the auto-and cross-terms in these distributions are presented and discussed. It is shown that the Wigner trispectrum is a more suitable analysis tool and it performance is compared to its second order counterpart for detecting impulsive signals. These methods are also applied to measured data sets from an industrial gearbox.

• Journal of applied mathematics & informatics
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• v.30 no.5_6
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• pp.1031-1049
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• 2012

In this paper, a class of impulsive fuzzy bi-directional associative memory (BAM) neural networks with distributed delays and variable coefficients are considered. Using Lyapunov functional method and fixed point theorem, we derived some sufficient conditions for the existence and globally exponential stability of unique periodic solution of the networks. The results obtained are new and extend the previous known results. In addition, an example is given to show the effectiveness of our results obtained.