• Explosives and Blasting
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• v.39 no.4
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• pp.12-21
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• 2021

In this study, a series of FEM numerical analyses was conducted to compare the resistance performance of concrete drainage protection facility to blast vibration. Two different types of ㅁ-shaped protection facility, which are suggested in the study, were compared to the traditional ㄷ-shaped one. In the analyses, the vibration resistances of the three protection facilities were evaluated under the varying conditions of the standoff distance from the explosion and charge weight per delay. As a result, it was found that the two proposed types of drainage protection facilities are superior to the traditional one in the vibration reduction performance.

• Journal of Energy Engineering
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• v.28 no.1
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• pp.65-72
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• 2019

The Korean government is aiming to produce 20% of the electricity using renewable energy sources by 2030. Ocean renewable energy sources which are abundant in South Korea can do an important role to achieve the goal. This paper introduces a tidal current energy converter utilizing flow induced vibrations which can efficiently work even in the currents slower than 1.0m/s and suggests optimal designs of the tidal energy converter based on speeds of the tidal currents in seven different coastal regions in South Korea. Moreover, the theoretical annual energy production by the tidal converter is estimated at theses costal areas. The total amount of the annual energy production by the tidal energy converter is predicted as 221.77 TWh which is equivalent to 42.3% of the electric consumption of South Korea in 2013. The result shows that the tidal current energy converter can be an important role to achieve the goal of the Korean government.

• Journal of KSNVE
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• v.26 no.1
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• pp.18-23
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• 2016

• Journal of The Korean Society For Urban Railway
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• v.6 no.4
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• pp.417-426
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• 2018

Piezoelectric shunt is an electric type damper capable of reducing the vibration of the structure. Vibration generated at the natural frequency of the structure are converted into electrical energy through the piezoelectric material attached to the structure. Electric energy can be dissipated by thermal energy using piezoelectric shunt composed of inductor and resistance to reduce vibration. In this paper, the equation for the optimum inductance required to reduce the vibration of the cantilever beam was examined and the vibration of the aluminum cantilever was reduced by using finite element analysis and experiments. In the finite element analysis, the mode shape and the strain energy distribution were calculated to examine the mounting position, and the vibration reduction of the cantilever was calculated by adjusting the inductance and resistance circuit values. In addition, in the experiment, a variable inductor module was used to reduce the vibration occurring at a specific frequency of the cantilever. Finally, based on the results of the finite element analysis and the experiment, it was verified that the piezoelectric shunt can effectively reduce the vibration of the cantilever.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.11
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• pp.2457-2464
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• 2011

In this paper, a vibration energy harvesting circuit using a piezoelectric device is designed. MPPT(Maximum Power Point Tracking) control function is implemented using the electric power-voltage characteristic of a piezoelectric device to deliver the maximum power to load. The designed MPPT control circuit traces the maximum power point by periodically sampling the open circuit voltage of a full-wave rectifier circuit connected to the piezoelectric device output and delivers the maximum available power to load. The proposed vibration energy harvesting circuit is designed with $0.18{\mu}m$ CMOS process. Simulation results show that the maximum power efficiency of the designed circuit is 91%, and the chip area except pads is $700{\mu}m{\times}730{\mu}m$.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.2
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• pp.125-131
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• 2003

In this paper Power Flow Finite Element Method(PFFEM) has been implemented to analyze the vibration of a plate in mid and high frequency ranges. In order to solve the vibration energy governing equation in Power Flow Analysis(PFA), The Finite Element Method(FEM) was used as a numerical tool. It allowed one to predict the distribution of displacement and Intensity in the plate vibrating at mid and high frequencies. The results were compared with the analytical solutions and the approximate FEM solutions. The comparison showed that PFFEM can be an effective tool to analyze the structural vibration in mid and high frequency ranges.

• Journal of the Korean Chemical Society
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• v.28 no.1
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• pp.26-33
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• 1984

The rate constants for the following vibration-to-vibration energy exchange reactions have been calculated theoretically for the temperature range from 300 to 800K and for n = 2 to 5. HF(v=n) + DF(v=0) ${\to}$ HF(v=n-l) + DF(v=l) + ${\Delta}E$(a) DF(v=n) + HF(v=0) ${\to}$ DF(v=n-l) + HF(v=l) + ${\Delta}E$(b) In calculation the loosely-held, non-rigid dimer collision model and semiclassical method have been employed. The results show that the rate constants for the processes (a) are much greater than those for the processes (b). Also, it is found that the rate constants for the processes (a) increase with decreasing temperature and with increasing quantum number, while those for the processes (b) show the opposite tendencies. These findings are explained in terms of the sign and magnitude of the energy mismatch, ${\Delta}E$.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.173-180
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• 2007

Oscillating wave amplitude in a bottom-mounted OWC chamber designed for wave energy converter is investigated by applying characteristic wave conditions in Korean coastal water. The effects of shape parameters of OWC chamber in a view of wave energy absorbing capability are analyzed. Both experimental and numerical approaches are adopted and their results are compared to optimize the shape parameters which can result in a maximum power production under given wave distribution. The experiment was carried out in a wave flume under 2-D assumption of OWC chamber. The numerical scheme employed a hybrid Green integral equation which adopts the Rankine Green function inside chamber to take account of fluctuating air pressure, while it uses the Kelvin Green function in outer domain. Air duct diameter, chamber width, and submerged depths of front skirt and back wall of chamber changes the magnitude and peak frequency of wave absorption significantly.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.539-543
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• 2014

This work investigated the electromechanical performance of a cantilevered vibration energy harvester incorporating the single crystal PMN-PZT, manufactured with the most recent technology of solid-state single crystal growth. Single crystal PMN-PZTs with two different crystallographic axes such as [011] and [001] were considered. For the [011] orientation, because material properties such as the stiffness, piezoelectric strain coefficients are not the same in the directions normal to the crystallographic axis, the effects of the transversely anisotropy on the magnitude and frequency bandwidth of output power were also analyzed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.11
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• pp.890-897
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• 2014

This work investigated the electromechanical performance of a cantilevered vibration energy harvester incorporating the single crystal PMN-PZT, manufactured with the most recent technology of solid-state single crystal growth. The performances of single crystal PMN-PZTs with two different crystallographic axes such as [011] and [001] are compared with those of PZT ceramics. From the investigations, it is shown that the [001]-poled PMN-PZT is advantageous for the excitations containing single dominant frequency component, while the single crystal [011]-$d_{32}$ is superior in terms of the energy storage density and energy conversion efficiency.