• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.5
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• pp.49-54
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• 2004

In order to evaluate the stability of chatter vibration in turning precess, the micro-positioning cutting test with artificial tool vibration by piezoelectric actuation were carried out. In experiment, the phase lags between cutting forces and chip thickness variations were measured, and the dimensionless penetration-rate coefficient（$\overline{K^*}$） which is the most important parameter on the stability for chatter vibration was calculated. The results show that$\overline{K^*}$ can be applicable to the stability criterion for regenerative chatter vibration.

• Journal of the Korean Institute of Gas
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• v.18 no.1
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• pp.68-74
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• 2014

In this study, to analyze the impulsive response of a helmet, a simple vibration model is presented. Based upon the experimental data and the simulation results, an equivalent one degree of freedom vibrational system is adapted, and transient impulsive responses are analysed to investigate the influence of engineering parameters such as damping, natural frequency, and impact velocity on the impulsive response of the helmet. Maximum gravitational acceleration reduces as the damping factor value increases. When the damping factor value is around 0.6 or larger, the maximum acceleration does not change. With respect to the natural frequency and the impact velocity, it increases linearly. The relationship between head injury criterion(HIC) and maximum gravitational acceleration is also presented. The scheme of this study is expected to be utilized to economize the design process of high quality helmets.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.11
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• pp.1144-1150
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• 2009

Appropriate vibration model is required to predict in advance the vibration level of a large vehicle which carries sensitive electronic/mechanical equipments and drives often on the unpaved and/or off-road conditions. Central tire inflation system(CTIS) is recently adopted to improve the mobile operation of military and bulletproof vehicles. In this paper, full vehicle model(FVM) having 11 degrees of freedom and equipped with CTIS has been developed for a large vehicle which has $8\times8$ wheels$\times$driving wheels. Usability of the developed model is validated via road tests for three different modes (i.e. highway, country, and mud/sand/snow modes) and for various velocity conditions. The developed FVM can be used to predict the vibration level of the large vehicle as well as to determine the driving velocity criterion for different road conditions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.9 s.114
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• pp.982-989
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• 2006

The centrifugal force acting on a rotating disk creates the in-plane loads in radial and circumferential directions. Application of fiber reinforced composite materials to the rotating disk can satisfy the demand for the increment of its rotating speed. However, the existing researches have been confined to lamina disks. This paper deals with the stress and vibration analysis of rotating laminated composite disks. The maximum strain theory for failure criterion is applied to determine the strength of the laminate disk from which the maximum allowable speed is obtained. Dynamic equation is formulated in order to calculate the natural frequency and critical speed for rotating laminated disks. The Galerkin method is applied to obtain the series solution. The numerical results are given for the cross-ply laminated composite disks.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.74-92
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• 2000

This study was performed to evaluate the working conditions In construction workers through measurements of working environments and to improve the working conditions and to design the appropriate environmental and health management system. The results of measurement for working environments in construction work are as following: 1. The excess rate of noise and dust concentration in express highway construction, road construction, building construction and interior painting was 28.6% and 24.5% respectively. 2. The excess rate of mixed organic solvents concentration in interior painting was 39.3%. 3. The chain type bulldozer has the highest level of vibration; the excess rate was 85.7%, and among the vibration instruments, the level of left hand's vibration of all vibrators exceeded the criterion and in the case of drilling all the level of vibration exceeded the criterion in both hands. On the basis of the results in this research the environmental and health management system for construction workers must be considered. Therefore, it is necessary to be introduced the special medical examination and measurement of working environments in construction industry. In defining "the working place" of Article 39 of Enforcement regulations of industrial safety and health act, the word "indoors" should be deleted. Then the eligible industry for measurement of working environment must be extended. And it is also necessary for construction industry to be performed group health management service by agencies such as other manufacturing industry.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.6
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• pp.192-199
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• 2002

Largely, there are three kinds of the design criteria of piping system in petrochemical plant. The first is on the pipe thickness in accordance with the design pressure of piping system. The second is on the static state evaluation by thermal growth and the other is on the dynamic evaluation by piping vibration. According to the ASME B31.3 code, the internal pressure design thickness fur straight pipe shall be calculated as a code formula. And the static design by thermal displacement is defined 7000 cycles of fatigue life in operating the piping system with a design condition. However, the dynamic design evaluation in comparative with small displacements of high frequencies to the static condition has not established clearly the method, yet. So, this study purposes to present the trial of a proposal of dynamic design criterion on the basis of static design method.

• Journal of KSNVE
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• v.7 no.6
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• pp.967-974
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• 1997

Distributed piezoeletric sensor and actuator have been designed for efficient vibration control of a cantilevered beam. Both PZT and PVDF have been used in this study, the former as an actuator and the latter as a sensor for the integrated structure. We have optimized the position and the size of the PZT actuator and the electrode shape of the PVDF sensor. Finite element method is used to model the structure and the optimized actuators, we have designed the active electrode width of the PVDF sensor along the span of the beam. Actuator design is based on the criterion of minimizing the system energy in the control modes under a given initial condition. Model control forces for the residual (uncontrolled) modes have been minimized during the sensor design to minimize the observation spill-over. Genetic algorithm and sequential quadratic programming technique have been utilized as an optimization scheme. Discrete LQG control law has been applied to the integrated structure for real time vibration control. Performance of the sensor, the actuator, and the integrated smart structure has been demonstrated by experiments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1993.04a
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• pp.107-112
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• 1993

The effect of the applied direction and magnitude of loads on the stability and natural frequency of flexible rotors is analyzed, when the rotors are subject to nonconservative torque and force. The stability criterion derived from the energy and variational principle is discussed and a general Galerkin's method which utilizes admissible functions is employed for numerical analysis. Illustrative examples are treated to demonstrate the analytical developments.

• Journal of Biosystems Engineering
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• v.17 no.4
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• pp.314-325
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• 1992

This paper reviews some relevant criteria for the evaluation of ride quality of agricultural tractors. Although there still exist many deficiences and shortcomings, ISO 2631 'Guide for the evaluation of human exposure to whole body vibration' may be the most pertinent criterion to the ride quality evaluation of tractors. The effects of ride vibrations on the human health and performance were also reviewed and summarized in general terms.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.358-363
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• 1997

The Operational Deflection Shape designates the motion pattern by which a structure vibrates under a specific operating condition. Modal Analysis is usually tested under test bench, but Operational Deflection Shape can be measured directly under real operating condition. It provide useful information for trouble-shooting and aid understanding and evaluation of the absolute dynamic behaviour of a machine or component. In this paper, It is analysed Excavator Upper Frame using Operating Deflection Shape.