• Aerospace Engineering and Technology
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• v.8 no.2
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• pp.113-121
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• 2009

Shaker system is used to simulate the vibration from the launch environment. The vibration tests are performed in the vertical and lateral direction. For the lateral vibration test, the slip table system is used with shaker system. For the latest large satellite, vibration test adaptor is made of the steel. But slip table of lateral vibration is made of magnesium, so there is big difference of thermal expansion ratio between slip table and vibration test adaptor. This paper encompasses the following items; verification process of thermal characteristics and overturning moment and a solution for lateral vibration test with steel vibration test adaptor.

• Geomechanics and Engineering
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• v.2 no.3
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• pp.177-190
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• 2010

This paper presents the details of indigenous development of the piezovibrocone and calibration chamber. The developed cone has a cylindrical friction sleeve of $150cm^2$ surface area, capped with a $60^{\circ}$ apex angle conical tip of $15cm^2$ cross sectional area. It has a hydraulic shaker, coupled to the cone penetrometer with a linear displacement unit. The hydraulic shaker can produce cyclic load in different types of wave forms (sine, Hover sine, triangular, rectangular and external wave) at a range of frequency 1-10 Hz with maximum amplitude of 10 cm. The piezovibrocone can be driven at the standard rate of 2 cm/sec using a loading unit of 10 ton capacity. The calibration chamber is of size $2m{\times}2m{\times}2m$. The sides of the chamber and the top as well as the bottom portions are rigid. It has a provision to apply confining pressure (to a maximum value of $4kg/cm^2$) through the flexible rubber membrane inlined with the side walls of the calibration chamber. The preliminary static as well as dynamic cone penetration tests have been done sand in the calibration chamber. From the experimental results, an attempt has been made to classify the soil based on friction ratio ($f_R$) and the cone tip resistance ($q_c$).

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.2
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• pp.83-88
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• 1973

The newly devised column set is better than the conventional method with centrifuge, suction filter instruments for saturating of the salt and washing out the excess of salt for C. E. C. determination in soils. 1. The new method has a high significance with one suction filter set. 2. The new method deminishes the time and effort of analysis by one third. It can analyze many samples at a time. 3. It is able to analyze without expensive instruments (e. g. vaccum pump, shaker, suction apparatus and centrifuge).

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.6
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• pp.67-73
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• 2022

Industrial inverters are used in a variety of fields for electric power supply. They may be exposed to vibration and heat once they are installed. This study focused on a framework of accelerated life testing of an industrial inverter considering fatigue damage as the primary source of deterioration. Instead of analyzing detailed failure mechanisms and the product's vulnerability to them, the potential of fatigue failure is considered using the fatigue damage spectrum calculated from the environmental vibration signals. The acceleration and temperature data were gathered using field measurement and spectral analysis was conducted to calculate the vibration signal's power spectral density (PSD). The fatigue damage spectrum is then calculated from the input PSD data and is used to design an accelerated fatigue life testing. The PSD for the shaker table test is derived that has the equivalent fatigue damage to the original input signal. The tests were performed considering the combined effect of random vibration and elevated temperature, and the product passed all the planned tests. It was successfully demonstrated that the inverter used in this study could survive environmental vibration up to its guarantee period. The fatigue damage spectrum can effectively be used to design accelerated fatigue life testing.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.6
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• pp.769-778
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• 2007

In this paper, excitation systems using linear mass shaker (LMS) and active tuned mass damper (ATMD) are presented in order to simulate the wind induced responses of a building structure. The actuator force for the excitation systems is calculated by using the inverse transfer function of a target structural response to the actuator. Filter and envelop function are used such that the error between the wind and actuator induced responses is minimized by preventing the actuator from exciting unexpected modal response and initial transient response. The analyses results from a 76-story benchmark building problem in which wind load obtained by wind tunnel test is given, indicate that the excitation system installed at a specific floor can approximately embody the structural responses induced by the wind load applied to each floor of the structure. The excitation system designed by the proposed method can be effectively used for evaluating the wind response characteristics of a practical building structure and for obtaining an accurate analytical model of the building under wind load.

• Steel and Composite Structures
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• v.4 no.5
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• pp.355-365
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• 2004

A new reduction method of residual stress in welding joint is proposed where welded metals are shaken during welding. By an experiment using a small shaker, it can be shown that tensile residual stress near the bead is significantly reduced. Since tensile residual stress on the surface degrades fatigue strength for cumulative damage, the proposed method is effective to reduction of residual stress of welded joints. The effectiveness of the proposed method is demonstrated by the response analysis using one mass model with nonlinear springs.

• Korean Journal of Mathematics
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• v.26 no.3
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• pp.425-437
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• 2018

In this paper, we linked the motion of spherical images with the motion of their curves. Surfaces generated by the evolution of spherical image of a space curve are constructed. Also geometric proprieties of these surfaces are obtained.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.273-276
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• 2000

Marine fungus, Thraustochytrium aureum ATCC 34034, was incubated in artificial sea water media in order to produce docosahexaenoic acid(DHA). Cultures were performed at $24^{\circ}C$ in light for 13 days with orbital shaker at 100rpm. Maximum cell productivity of 1.34g/L and DHA yield of 41.4 mg/L were obtained by using this method, which is almost the twice level of DHA yield obtained for the strains reported previously. This strain did produce much more DHA after sporangium disruption.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.351-355
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• 1996

유연한 보의 진동문제에 대해 Filtered-X LMS 알고리즘을 이용하여 제어계를 구성하고 디지탈 신호처리보드를 이용하 여 실시간 제어를 수행하였다. 제어 엑추에이터로는 피에조 세라믹을 사용하였고 정현파 및 백색잡음 형태의 외력으 로 Shaker를 이용하여 보를 가진하였다. 백색잡음가진 실험결과 1차 고유진동수에서 14dB의 진동저감을 할 수 있었 으며 관심 주파수영역내에서진동이 고르게 저감되었다.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.3
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• pp.46-59
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• 1989

The purpose of test fixture is to mechanically couple energy from a shaker into a test specimen. And then it is necessary to design a fixture of shich the fundamental natural frequency is over than one half times as high as the highest frequency of interest. But the dynamic behavior of vibration test fixture is usually different from, often far different from, what has been calculated. In this paper, the optimal dimensionless frequency parameter, ${lambda}$'s, are calculated from the test results of a various and complex shaped fixtures.