• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1394-1399
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• 2001

The purpose of this paper is that investigates the dynamic behavior characteristic of W.T.S(Wind Turbine System) and carries out the evaluation analysis during operating W.T.S. To investigate the dynamic behavior characteristic of W.T.S. the experiments to measure vibration of the blade from the attached accelerometer on the flap and edge section of the blade that is one of the most important elements of dynamic characteristic of W.T.S are performed. Natural frequency and mode shape are calculated with commercial program (STAR MODAL) using the measured vibration acceleration that receives the signal with F.F.T Analyzer from the accelerometer. For validation of these experiments. the finite element analysis is performed with commercial F.E.M Program (ANSYS) on the basis of the natural frequency and mode shape. The results indicate that experimental values have good agreements with the finite element analysis.

• International Journal of Highway Engineering
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• v.19 no.2
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• pp.87-95
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• 2017

PURPOSES : The objectives of this study are to evaluate moisture sensitivity of various asphalt mixtures and to suggest an alternate method for the dynamic immersion test, which is used to determine the application of anti-stripping agent, by analyzing bond strength. METHODS : The bond strength of various asphalt mixtures such as hot mix asphalt, warm mix asphalt, and polymer-modified asphalt was evaluated by the ABS test. In order to characterize moisture sensitivity at different temperatures of the mixtures, the ABS test was conducted at $-10^{\circ}C$, $5^{\circ}C$, $20^{\circ}C$, $40^{\circ}C$, and $54^{\circ}C$ under both dry and wet conditions. The concept of the bond strength ratio was applied for objective moisture sensitivity analysis. Moreover, the bond strength characteristic was compared to the dynamic immersion test to suggest an alternate method to determine the application of anti-stripping agent. RESULTS AND CONCLUSIONS : Overall, the polymer-modified asphalt demonstrates the highest bond strength characteristic regardless of moisture condition and temperature. The bond strength characteristic displays a highly reliable linear relationship from $5^{\circ}C$ to $40^{\circ}C$, and the relationship could be used to predict bond strength at any intermediate temperature. Based on the analysis of bond strength and retained asphalt ratio, the bond strength value of 1254 kPa could be applied as a criterion for anti-stripping agent.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.6
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• pp.596-605
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• 2022

In this study, analysis of dynamic characteristics and flight vibration was performed to unmanned aerial vehicles. The analysis model was supplemented by performing a dynamic characteristic test and a random vibration test using manufactured dummy aerial vehicle. For the dynamic characteristic test, a bungee cable was used to implement the free end boundary condition. Prior to the flight vibration test using a multiple electric shaker, a random vibration test was performed to predict the excitation force during the actual flight vibration test. It was judged that the actual test could be predicted more accurately by supplementing the analysis model from the test results. In addition, it was possible to determine the feasibility of the test by predicting the excitation force of the flight vibration test.

• Korean Journal of Agricultural Science
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• v.51 no.3
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• pp.295-305
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• 2024

Due to the environment of irregular soil characteristic for agricultural fields, dynamic characteristic occurs in the tractor cabin during agricultural operations. Operator's fatigue is increased, and operation performance is decreased by these irregular environment conditions. This study was conducted to measure and analyze the dynamic characteristic of a tractor cabin, a major agriculture machinery, during agricultural operations. The specification of tractor used in the study was a 95 kW class tractor. To analyze the dynamic characteristics of the tractor cabin, the main agricultural operations, plow tillage and rotary tillage, were selected. To measure data of dynamic characteristic of the cabin, which continuously changes during operations, an Ellipse Series INS (inertia navigation system) with a built-in IMU (inertia measurement unit) was attached to the center of gravity of the cabin. During field test, the gear stages of plow tillage were B4 (4.3 km·h^-1) and B5 (5.6 km·h^-1), and the gear stages of rotary tillage were A3 (3.3 km·h^-1) and A4 (4.2 km·h^-1), which are the most commonly used. To analyze dynamic characteristic such as roll and pitch during operations according to the gear stages. As a result, the dynamic characteristics of pitch increased more than the dynamic characteristics of roll as the travel speed increased, and the dynamic characteristics of both agricultural operations were in the range of 2 to 5°.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.5
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• pp.389-396
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• 2002

In this study, the dynamic absorbing system for gas operated gun has been investigated. For this purpose, firstly. mathematical model of gas-operated shoulder-fired gun has been constructed. Through a series of experimental works using the devised test setup, the characteristic behavior of mathematical model was compared to the test results. In order to design the dynamic absorbing system, parameter optimization process has been performed based on the simplified isolation system under constraints of moving displacement and transmitted force. In order to implement the more efficient dynamic absorbing system, the characteristic performance of stroke-dependent variable damping system has been analyzed with some opening area curves. Finally, the performance of the designed dynamic absorbing system has been evaluated by simulation and experiment using the previous test apparatus.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.256-261
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• 2014

Endurance test procedures of multipurpose tactical vehicle is constructed by comparing the Korea defence standard and TOP-2-2-506. The plan was to make the best reflect the operational environment and the actual production purposes. Endurance test of multipurpose tactical vehicle more stringent than the existing other military vehicles validation procedures. But the test plan, it is possible to reduce the cost and schedule of long verification that occurs because of the Endurance test. Through a comparison of the dynamic characteristic analysis, change of test center was to ensure the reliability and validity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1399-1411
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• 2012

The grid frequency is controlled cooperatively by the governor of the Turbine-Generator and the automatic generation controller(AGC) of the KPX(Korea Power Exchange). It is a basic requirement that the reliability of the governor is verified to enhance the power system stability but it is not easy to confirm the response characteristics of the governor because all generators are operated in the grid system that has the constant voltage and frequency. Therefore, it is necessary to study a new test method in order to examine the governor dynamic characteristic in the similar fault conditions. A study has shown that it is verified to simulate the turbine-generator power control system, the governor response characteristic under limited conditions and contribution of AGC with the gas turbine generator simulation model as well as demonstrate the dynamic response of the governor with the developed governor dynamic characteristic tester based on digital controller while the turbine-generator is connected to the grid system. This tester is constructed by the built-in functions of the turbine-generator main controller. In this treatise, the theoretical background, development method and the results of both simulations and demonstrations are described as another way to verify the turbine-generator governor dynamic characteristics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.52-56
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• 2011

Recently, KARI(Korea Aerospace Research Institute) has been developing a modern 11.5m diameter four bladed bearingless main rotor system, and this rotor system can be used for 7,000lb class helicopter. Flexbeam and torque tube can be considered as the key structural components, and large elastic twist of flexbeam induced by pitch control motion of torque tube can influence the nonlinear aeroelastic behavior. In this paper, the dynamic characteristic analysis results of bearingless rotor system were presented. In order to construct a input model and validate the analysis procedures, calculated results using the comprehensive helicopter analysis program CAMRAD II were compared with the measured natural frequencies and lag damping data from small-scale wind tunnel test. Next, the analysis model was extended to a full-scale model, and the dynamic analysis results were presented.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.2
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• pp.187-192
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• 2012

Recently, KARI(Korea Aerospace Research Institute) has been developing a modern 11.5 m diameter four bladed bearingless main rotor system, and this rotor system can be used for 7,000 lb class helicopter. Flexbeam and torque tube can be considered as key structural components, and large elastic twist of flexbeam induced by pitch control motion of torque tube can influence the nonlinear aeroelastic behavior. In this paper, the dynamic characteristic analysis results of bearingless rotor system were presented. In order to construct a input model and validate the analysis procedures, calculated results using the comprehensive helicopter analysis program CAMRAD II were compared with the measured natural frequencies and lag damping data from small-scale wind tunnel test. Next, the analysis model was extended to a full-scale model, and the dynamic analysis results were presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1037-1038
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• 2013