• 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.964-970
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• 2006

Micro gas turbine(MGT) has received attention recently as small-scale distributed power sources. With characteristics such as their small size, lightweight, low maintenance cost and minimal vibrations during operation, they are expected to become widespread in a wide range of ' applications, including residential and small-scale industrial use. It is very easier to start-up and stop the MGT system which is the friendly environmental power system has just below the 9ppm NOx emmission and good quality of noise level. The exhaust heat emitted by the MGT is in the form of about $300^{\circ}C$ clean exhaust gas. The exhaust gas is suitable for absorption chiller/heater system. 1 has researched performance characteristics of the 60 kW class MGT-absorption chiller-heater system in the local condition. Variations of heat recovery from exhaust gas has measured according to micro gas turbine output of 15, 30, 45, 60kW. From those results, the performance of the MGT-absorption chiller/heater system has been evaluated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.8
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• pp.809-815
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• 2009

The previous work(Cheong et al., 2006) where the characteristics of acoustic emissions of wind turbines has been investigated according to the methods of power regulation, has showed that the acoustic power of wind turbine using the stall control for power regulation is more correlated with the wind speed than that using the pitch control. In this paper, basically extending this work, the noise generation characteristics of large modern upwind wind turbines are experimentally indentified according to the power regulation methods. To investigate the noise generation mechanisms, the distribution of noise sources in the rotor plane is measured by using the beam-forming measurement system(B&K 7768, 7752, WA0890) consisting of 48 microphones. The array results for the 660 kW wind turbine show that all noise is produced during the downward movement of the blades. This result show good agreement with the theoretical result using the empirical formula with the parameters: the convective amplification; trailing edge noise directivity; flow-speed dependence. This agreement implies that the trailing edge noise is dominant over the whole frequency range of the noise from the 660 kW wind turbine using the pitch control for power regulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.63-67
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• 2009

The previous work (Cheong et al., 2006) where the characteristics of acoustic emissions of wind turbines has been investigated according to the methods of power regulation, has showed that the acoustic power of wind turbine using the stall control for power regulation is more correlated with the wind speed than that using the pitch control. In this paper, basically extending this work, the noise generation characteristics of large modern upwind wind turbines are experimentally indentified according to the power regulation methods. To investigate the noise generation mechanisms, the distribution of noise sources in the rotor plane is measured by using the Beam-forming measurement system (B&K 7768, 7752, WA0890) consisting of 48 microphones. The array results for the 660 kW wind turbine show that all noise is produced during the downward movement of the blades. This result show good agreement with the theoretical result using the empirical formula with the parameters: the convective amplification; trailing edge noise directivity; flow-speed dependence. This agreement implies that the trailing edge noise is dominant over the whole frequency range of the noise from the 660 kW wind turbine using the pitch control for power regulation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.5 s.122
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• pp.448-455
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• 2007

As Decentralized Generation(DG) becomes more reliable and economically feasible, it is expected that a higher application of DG units would be interconnected to the existing grids. This new market penetration of DG technologies is linked to a large number of factors like technologies costs and performances, interconnection issues, safety, market regulations, environmental issues or grid connection constrains. This paper describes the procedures and results for the mechanical, electrical, and environmental tests of MGT on actual grid-connection under Korean regulations. As one of the achievements, the simulation model of MGT was developed, so that it will be able to analyze or propose new distributed generation system using MGT. The field test was conducted in order to respond to a wide variety of needs for noise reduction and utilization and its performance was evaluated in consideration of its operational problems. The MGT is successfully supplying electricity to Korean grids with satisfying various regulations. The suggested strategy and experience for the evaluation of the distributed generation will be used for the introduction of other distributed generation technologies into the grid in the future.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.1
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• pp.71-78
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• 1999

This paper presents a new type of energy generative ER suspension system which does not require external power sources. This is accomplished by converting vibration energy(kinetic energy) into electrical energy. In order to undertake this, an appropriate size of the ER damper is manufactured by incorporation a mechanism which changes the linear motion of the ER damper to the rotary motion. This rotary motion is amplified by gears and activates a generator to produce the electrical energy. The efficiency of energy generation is evaluated and the level of damping force with generated power is also investigated. Then, the ER suspension system is applied to the quarter car model, and its vibration isolation is experimentally evaluated with respect to the piston speed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.8
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• pp.1951-1962
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• 1993

The creation process of a typical machined surface is treated here as a dynamic system. An investigation is carried out to establish a relationship between the characteristics of cutting force fluctuations that cause vibration response of the tool-workpiece system and the formation of surface in face cutting by sintered carbide cutting tool. Cutting force is measured and analyzed in frequency domain. The power spectral densities of cutting force give a useful information in surface generation and it can be used to find out the control factor of surface roughness. The terms, PSD ratio & Normalized spindle frequency PSD, are defined and when the value of power in spindle frequency is absolutely little but relatively large, it is obtained high accuracy surface roughness. The aim of this research is to find surface profile by measured and analyzed cutting force signals. The simulation of surface generation gives the comprechension of its mechanism and help to predict and control the surface quality. In this study, it is suggested what informations about surface generation can be acquired from the cuttuing force signal and an way of generating a better surface.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.1
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• pp.14-19
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• 2017

Fuel oil consumption cost varies depending on every ship operation and this roughly amounts to 70 % of shipping companies' total revenue. As such, efforts towards improved fuel economy are being pursued. An annual 1 % reduction in fuel consumption is perceived to result in saving tens million US dollars on the global fleet operation. One approach is the application of power take-off configurations which are seen to increase fuel oil economy and are suitable for power generation. In this study, the dynamic properties of a shaft generator coupled on a 10S90ME main engine of an 18 600 TEU container vessel is presented. The vibratory torque and angular velocity variation was examined through theoretical analysis and actual vibration measurement. The result of the study suggests a review on existing classification rules for generator design and the lowering of vibratory torque and angular velocity variation guideline.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.219-219
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• 2008

Energy harvesting from the environment has been of great interest as a standalone power source of wireless sensor nodes for ubiquitous sensor networks (USN). There are several power generating methods such as thermal gradients, solar cell, energy produced by human action, mechanical vibration energy, and so on. Most of all, mechanical vibration is easily accessible and has no limitation of weather and environment of outdoor or indoor. In particular, the piezoelectric energy harvesting from ambient vibration sources has attracted attention because it has a relative high power density comparing with other energy scavenging methods. Through recent advances in low power consumption RF transmitters and sensors, it is possible to adopt a micro-power energy harvesting system realized by MEMS technology for the system-on-chip. However, the MEMS energy harvesting system hassome drawbacks such as a high natural frequency over 300 Hz and a small power generation due to a small dimension. To overcome these limitations, we devised a novel power generator with a spiral spring structure. In this case, the energy harvester has a lower natural frequency under 200 Hz than a normal cantilever structure. Moreover, it has higher an energy conversion efficient because shear mode ($d_{15}$) is much larger than 33 mode ($d_{33}$) and the energy conversion efficiency is proportional to the piezoelectric constant (d). We expect the spiral type MEMS power generator would be a good candidate as a standalone power generator for USN.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.12
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• pp.1164-1171
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• 2012

Recently, researches related to the green energy generation systems have increased significantly. Among them wind turbines are the most spread practical green energy generation systems. In order to enhance the power generation capacity of the wind turbine blade, the length of wind turbine blade has increased. It might cause undesirable excessive dynamic loads. Therefore dynamic characteristics of a wind turbine blade system should be identified for a safe design of the system. In this study, the equations of motion of a wind turbine blade system undergoing gravitational force are derived considering wind force and pitch angle. Effects of wind speed, variation of pitch angle of the wind turbine blade, rotating speed, and the blade length on its stability characteristics are investigated.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.4
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• pp.147-154
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• 2024

This study focuses on the modeling and analysis of the linear generator for a bladeless wind power generation to overcome the limitations and drawbacks of conventional wind turbines. A bladeless wind power generation system has the advantages of low land requirement for installation and maintenance cost compared to a blade wind power turbine. Nevertheless, question concerning the generator topology are not satisfying answered. The goal of the research is to compare and analyze the characteristics of horizontal and vertical structures of linear generator for bladeless wind power systems. The proposed topology will be analyzed using magnetic energy by equivalent magnetic circuit method, and then it has been compared and evaluated by finite element method. The results of this project will give elaborate information about new generator structures for wind power system and provide insights into the characteristics of bladeless wind power generation.