• Journal of KSNVE
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• v.8 no.1
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• pp.75-80
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• 1998

It is a well known fact that the shaker used in the vibration test interacts with the test structure and thus influences the test results. A two degree of freedom model of shaker is suggested and the vibration parameters of this model is experimentally extracted. According to this experimental results, the vibration parameters of the shaker can vary with respect to the test structure as well as the stinger used in the connecting mechanism. It is also found that the vibration parameters of the shaker provided by the manufacturer can not be accurate and these parameter values should be revaluated based on the test environments.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.1
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• pp.147-153
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• 2001

This paper proposes a shaker system design for acceleration test of gimbal. Main reason of shaker system design is to give acceleration to the gimbal, which is moving and tracking the target on the tracking test equipment. The shaker system is mounted on the tracking test equipment. It uses the scotch yoke mechanism to have the constant movement in return. The Scotch yoke mechanism changes the rotational movement of constant velocity to simple harmonic motion.

• Advances in aircraft and spacecraft science
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• v.7 no.1
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• pp.79-90
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• 2020

The dynamic coupling between shaker and test-article has been investigated by recent research through the so called Virtual Shaker Testing (VST) approach. Basically a VST model includes the mathematical models of the test-item, of the shaker body, of the seismic mass and the facility vibration control algorithm. The subsequent coupled dynamic simulation even if more complex than the classical hard-mounted sine test-prediction, is a closer representation of the reality and is expected to be more accurate. One of the most remarkable benefits of VST is the accurate quantification of the frequency down-shift (with respect to the hard-mounted value), typically affecting the first lateral resonance of heavy test-items, like medium or large size Spacecraft (S/Cs), once mounted on the shaker. In this work, starting from previous successful VST experiences, the parameters having impact on the frequency shift are identified and discussed one by one. A simplified analytical system is thus defined to propose an efficient and effective way of calculating the lower bound frequency shift through a simple equation. Such equation can be useful to correct the S/C lateral natural frequency measured during the test, in order to remove the contribution attributable to the shaker in use. The so-corrected frequency value becomes relevant when verifying the compliance of the S/C w.r.t. the frequency requirement from the Launcher Authority. Moreover, it allows to perform a consistent post-test correlation of the first lateral natural frequency of S/C FE model.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.1
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• pp.111-119
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• 2019

PURPOSE: The aim of this study was to determine how biofeedback training with Shaker exercise effects the activation of the cervical myocardial muscle in stroke with swallowing disorder. METHODS: From June 2018 to September 2018, 30 patients who were hospitalized at C hospital and K hospital in Daegu, and K hospital in Gumi were surveyed to meet the criteria for selection. The participants were classified into three groups, and Shaker exercise was applied three times a day, five times a week, for four weeks; visuoauditory biofeedback group (VABG), visual biofeedback group (VBG), and self-exercises group (SG). In addition, the suprahyoid muscle activity was performed three times (before intervention, after intervention, and after two weeks). RESULTS: The pre and post-test comparisons, revealed a significant difference between the three groups (p<.01); VABG had the highest suprahyoid muscle activity. The post-test and follow-up test produced similar results in, the three groups (p>.05). The mean comparison showed the smallest difference in VABG, indicating that muscle persistence was the best. CONCLUSION: Shaker exercise has an effect on suprahyoid muscle activation. Biofeedback training, which provides an input of multi-sensory information in swallowing disorder treatment is recommended because it has the greatest effect when combined with visuoauditory biofeedback.

• 재활복지
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• v.20 no.3
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• pp.179-193
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• 2016

Chin Tuck Against Resistance Exercise(CTARE) and Shaker exercise is used to common for strengthening of suprahyoid muscle. No previous studies was compare of two exercises for patients with dyaphagia. This study investigated the effects of CTARE and Shaker exercise on suprahyoid, sternocleidomastoid muscle activity in stroke older patients with dysphagia. Ten stroke patients with dyaphagia voluntarily participated in this study. All subjects was performed in the order in the CTARE (isometric, isokinetic), Shaker (isometric, isokinetic), and repeated each ten trials. After CTARE was performed, subjects took a 5 min wash out period to minimize muscle fatigue. Activity of suprahyoid and sternocleidomastoid muscle during two training was analyzed using surface electromyography(sEMG). Wilcoxon signed rank test was used to assess differecences for muscles activity between the effects of the CTAR and Shaker exercise within group. CTARE and Shaker exercise showed no significant difference activity in suprahyoid muscle(p > .05). CTARE showed significantly lower muscle activity in sternocleidomastoid muscle than Shaker exercise(p < .05). CTARE in stroke older patients with dysphagia may be a effective intervention to improve swallowing function than Shaker exercise.

• Advances in aircraft and spacecraft science
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• v.5 no.2
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• pp.165-175
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• 2018

Jet Propulsion Laboratory has traditionally performed system level vibration testing of flight spacecraft. There have been many discussions in the aerospace community for more than a decade about spacecraft vibration testing benefits or lack thereof. The benefits and potential issues of fully assembled flight spacecraft vibration testing are discussed herein. The following specific topics are discussed: spacecraft screening test to uncover workmanship problems for launch dynamics environments, force- and moment-limited vibration testing, potential issues with structural frequency identification using base shake test data, and failures related to vibration shaker testing and ways to prevent them.

• Journal of the Semiconductor & Display Technology
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• v.14 no.1
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• pp.31-37
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• 2015

This paper is on the design and manufacturing of vibration tester (shaker) for experiments about effects on the performance of semiconductor chips and Li-ion batteries by vibration. Shaker in the market are quite expensive, it is difficult for basic researchers to contact. In this study, in order to improve this, we designed and manufactured with an entry-level into mass production possible approaches in terms of performance required to a minimum. The shaker system is operated by Matlab and LabView. The target performances are 200Hz frequency and 5% error, and these were satisfied.

• Journal of Mechanical Science and Technology
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• v.17 no.11
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• pp.1732-1738
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• 2003

The test specimen in environmental vibration test is connected to the fixture through several attachment points. The forces generated by the shaker must be transmitted equally to all attachment points. The forces transmitted to attachment points, however, are different because of the flexural vibration of the fixture. The variations of the transmitted force cause the under-test, especially at anti-resonance frequencies, in vibration test control. Anti-resonance frequencies at the attachment points of the fixture must be same in order to avoid the under-test in vibration test control. The structural modification of the fixture is needed so that anti-resonance frequencies at attachment points have the same value. In this paper, the method to calculate the anti-resonance frequencies and those sensitivities is presented. This sensitivity analysis is applied to the structural modification of the fixture excited at multi-points by the shaker. The antiresonance frequencies at the attachment points of the fixture can have the same value after structural modification, and the under-test in the vibration test control can be removed. Several computer simulations show that the proposed method can remove the under-tests, which are not removed in conventional vibration test control.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.2 s.54
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• pp.27-38
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• 2007

A series of forced vibration tests and ambient vibration measurement was conducted on a four-story reinforced concrete building damaged in the 1994 Northridge earthquake. Both low amplitude broadband and moderate amplitude harmonic excitation were applied using a linear shaker and two eccentric mass shakers, respectively, and ambient vibrations were measured before and after each forced vibration test. Accelerations, interstory displacements, and curvature distributions were monitored using accelerometers, LVDTs and concrete strain gauges. Natural frequencies and the associated mode shapes fur the first 7 modes were identified. Fundamental frequencies determined from the eccentric mass shaker tests were 70% to 75% of the values determined using ambient vibration data, and 92% to 93% of the values determined using the linear shaker test data. Larger frequency drops were observed in the NS direction of the building, apparently due to damage that was induced during the Northridge earthquake.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.2
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• pp.88-98
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• 1998

A waveform for shock response spectrum test on a shaker is synthesized using wavelets such that a specified shock response spectrum of a test profile is achieved. The parameters of a wavelet are center frequency, amplitude, number of half cycles, delay and polarity. The amplitude of each wavelet component is iteratively adjusted so a specified shock response spectrum is matched. The waveform so synthesized is regarded as a reference acceleration waveform for a shaker shock response spectrum test. The author proposes the use of a long duration and low peak waveform. The usefulness of this approach is illustrated with some examples.