• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.12
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• pp.27-34
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• 2018

This paper considers the seismic performance of lever-type tuned mass damper(TMD). The lever-type TMD is designed utilizing the seismic-performance of TMD and the control force required for constraining story drift. The TMD is basically designed by tuning the frequency of primary structure. Thus, the TMD plays an important role to reduce the dynamic responses. The lever-type TMD has a merit to control more displacement responses than the existing TMD due to the control forces. It is shown that the optimum design of lever-type TMD is affected by the ratio of the TMD mass with respect to the mass of the primary structure, the damping ration of the primary structure, and the length ratio of the lever. A numerical example exhibits the effectiveness of the dynamic control by the lever-type TMD and its validity is illustrated in a three-story building structure subjected to earthquake.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.2
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• pp.187-194
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• 2016

Parametric study on the lever type dynamic anti-resonance vibration isolator (DAVI) is executed to introduce the system in the path of vibration transmission for the vibratory response attenuation. The effects of inertia and location of the lever on the system performances are investigated using FEA. The effects of other parameters such as ratio of lever lengths, ratio of masses and the location of pivot are studied with analytical approach. According to the results, all the parameters except lever location affect the system response in their own ways. Consequently, the optimal lever type DAVI for translational or rotational system can be efficiently designed by selecting system parameters using the procedure introduced in this study.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.720-723
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• 2004

Lever mechanisms are usually employed to enlarge output displacement in precision stages. In this study, theoretical analysis of a lever is presented including bending effect and relation between dimension parameters and an objective function. The objective function is chosen as multiplication of magnification ratio and forcedisplacement transmission. Through theoretical analysis, this study presents optimal values for the parameters and the analysis is verified by finite element method.

• Communications of Mathematical Education
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• v.20 no.4 s.28
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• pp.621-634
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• 2006

In this study we describe the characteristics of solving geometry problems related with the ratio of segments using the principle of the lever and the center of gravity, compare and analyze this problem solving method with the traditional Euclidean proof method and the analytic method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1273-1276
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• 2005

A displacement magnification mechanism is usually employed in a nano-positioning stage to achieve a large stage motion. A lever mechanism is the most widely used displacement magnifying mechanism. For more large stage motion, double or multiple lever mechanisms can be used. In this case, a more accurate analysis model is needed. This study proposes a more reasonable analysis model for a multiple lever mechanism based on the single lever mechanism model. This paper describes that the high equivalent stiffness of the lever is the most important factor reducing the magnification ratio of the lever mechanism through increasing the deflection of the link and including the axial displacement of the pivot.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.121-129
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• 2005

Lever mechanisms are usually employed to enlarge output displacements in precision stages. In this study, theoretical analysis is done for a precision stage employing a lever and flexure hinges, including bending effect. This study presented relations between design parameters and magnification ratio. This study presents optimal values for the parameters to achieve a longer stage displacement. The analysis is verified by finite element analysis. It is found that adjusting stiffnesses can increase the travel range significantly.

• Journal of the Optical Society of Korea
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• v.12 no.4
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• pp.303-308
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• 2008

Directly modulated fiber-optic links generally suffer higher link loss and larger signal distortion than externally modulated links. These result from the electron-photon conversion loss and laser modulation dynamics. As a method to overcome the drawbacks, we have experimentally demonstrated the RF performance of directly modulated, ultra-strong injection-locked gain-lever distributed Bragg reflector (DBR) lasers. The free-running DBR lasers exhibit an improved amplitude modulation efficiency of 12.4 dB under gain-lever modulation at the expense of linearity. By combining gain-lever modulation with ultra-strong optical injection locking, we can gain the benefits of both improved modulation efficiency from the gain-lever effect, plus improved linearity from injection locking. Using an injection ratio of R=11 dB, a 23.4-dB improvement in amplitude response and an 18-dB improvement in spurious-free dynamic range have been achieved.

• Journal for History of Mathematics
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• v.23 no.4
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• pp.47-58
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• 2010

This study suggests new interpretation about ancient mathematician Archimedes' 'method'. For this, we examined the core issue related to the interpretation of the 'method' and identified the unclear relation between the principle of the lever and the indivisibles, both of which have consisted of the main point of arguments. And by having conducted the exploratory historical guesswork about Archimedes' careful use of indivisibles, we make a hypothesis that the role of the principle of the lever in Archimedes' 'method' should be the control of ratio of change.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.2
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• pp.60-65
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• 2008

The high-technology industries including a semi-conductor and an information communication need an ultra-precision technology from the technological points of view. Nano technology based on an ultra-precision technology is being studied to overcome the delicate technology that may occur in the semi-conductor fields. Then, the transferring equipment with high resolution and long displacement becomes an important technology. The goal of this study is to analyze the displacement magnification mechanism driven by piezoelectric actuator which has high resolution and fast response characteristics using flexure hinge with the merits of soft displacement, negligible back-lash and stick-slip, and no-lubrication. The analyses to reduce the magnification losses occurred during the magnification process are performed using ANSYS software based on FEM. The five design variables such as arm thickness, thickness of hinge, radius of hinge, length of input side at the 1st lever and magnification ratio of 1st lever are optimized to induce the maximum magnification ratio using Taguchi method.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.3 no.1
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• pp.37-47
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• 1995

It is very important to determine the performance and operating envelope of engine for aircraft's flight. The basic performance is provided by manufacturer, but installed engine's operating envelop is only determined by flight test. First, this study was measured cylinder head temperature(CHT), exhaust gas temperature(EGT) and oil temperature. At pre-determined altitude and power rate, these temperatures were measured by change of mixture ratio and mixture ratio condition for economic operation and max. power were found. And secondly, with the measured temperatures, possible positions of mixture lever were determined by flight test for stable flight Chang-91 and Lycoming IO-360-A series four cylinders engine with 200 hp was used for this study.