• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.248-252
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• 2007

As Waterpower Generation generates electricity using the difference of altitude of water, also let the turbine revolves through water pipe, at this time the revolving turbine causes exceedingly huge noise. Accordingly, not only those workers in the hydraulic turbine dynamo room are suffering the difficulties in mutual communication, but also those workers in the adjacent office are enduring the obstruction to the business due to the noise. Therefore, this Study has analyzed the reduction effect on the noise of hydraulic turbine dynamo room utilizing computer simulation, through the preceding research with the optimized model for architectural acoustic factor of the hydraulic turbine dynamo room. It is considered that such research result could be applied as the useful material for improvement of acoustic performance and noise-reduction effect at other similar hydraulic turbine dynamo room in the future.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.133-137
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• 2007

As the waterpower generation plant, the subject of this Study, is a facility that produces plenty of electricity corresponds to $196{\sim}240GWh$ annually, and in its generation process it creates a loud noise when the turbine related to the hydraulic turbine dynamo revolves, and since such loud noise must be transmitted to the dynamo room and amplified, it is effecting a lot of influences to the adjacent office and space. In such viewpoint, this Research, based on the soundproof measure presented at the preceding research, has attempted to evaluate about the effect of noise-reduction countermeasure against the hydraulic turbine dynamo using Auralizational Technique through Psycho-Acoustics Experiment. It deems that such result could be applied hereafter as the useful material when setting up a soundproof countermeasure for the hydraulic turbine dynamo room in dam.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.253-257
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• 2007

In case of the hydraulic turbine dynamo room at Dam, due to its big volume and reflexible finishing material, since the noise of electricity-generation is amplifying, it influences the difficulty of mutual communication among the workers, also it is causing both mental and physical damages to those workers in the neighboring office. Accordingly, after presentation of the optimized renovation model of the hydraulic turbine dynamo room using the acoustic simulation, this Research has compared and evaluated them using the auralizational technique between the present condition of "before improvement" and the acoustic condition of "after improvement". As the result of psycho-acoustics experiment, as the acoustic conditions at both "before & after Improvement" were apparently compared, it appeared that there is a considerable amount of noise-reduction effect at psycho-acoustics. It is considered that such material could be utilized as the valuable data hereafter for the time when any construction and renovation of the hydraulic turbine dynamo room and other similar workshop.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.263-267
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• 2007

Even though Waterpower Generation as pollution-free has its own merit of contribution by supply of good quality electricity, due to the noise made at the time of its operation, a normal mutual communication among the workers and technicians engaging at the hydraulic turbine dynamo room is almost impossible, and since those finishing materials had been used mainly by reflection material, it is actual situation that when working for maintenance in the hydraulic turbine dynamo room, as counterpart's voice vibrates, its working efficiency is difficult to ensure. On such view point, this Research has conducted Psycho-acoustics Experiment about voice Definition using Auralizational Technique, on the object for the hydraulic turbine dynamo room that improved its acoustic performance by computer simulation. As the result of Study, it was known that the clearness of sound with regard to voice information transmission was apparently improved in all items than before improvement. Therefore, it is considering that these results would be utilized usefully when renovation on the hydraulic turbine dynamo room in the future.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.49.1-49.1
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• 2015

The origin of magnetic fields in the intracluster medium (ICM) is uncertain: it can be either primordial or astrophysical. Turbulence plays important roles in the origin of magnetic fields in the ICM. This is because turbulence can amplify a weak seed magnetic field very efficiently. The efficiency of the turbulence dynamo critically depends on the magnitude of viscosity: the smaller the viscosity is, the more efficient the turbulence dynamo is. In this talk, I'll discuss turbulence dynamo in both very small viscosity limit and very large viscosity limit. I'll show that when the viscosity in the ICM is comparable to the Spitzer viscosity, the origin of magnetic field in the ICM is likely to be astrophysical. On the other hans, when the viscosity is much smaller than the Spitzer value, the origin of magnetic field can be either astrophysical or primordial.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.155-158
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• 1996

Magnetic fields correlated on several kiloparsec scales are seen in spiral galaxies. Their origin could be due to the winding up of a primordial cosmological field or due to amplification of a small seed field by a turbulent galactic dynamo. Both options have difficulties: There is no known battery mechanism for producing the required primordial field. Equally the turbulent dynamo may self destruct before being able to produce the large scale field, due to excess generation of small scale power. The current status of these difficulties is discussed. The resolution could depend on the nature of the saturated field produced by the small scale dynamo. We argue that the small scale fields do not fill most of the volume of the fluid and instead concentrate into intermittent ropes, with their peak value of order equipartition fields, and radii much smaller than their lengths. In this case these fields neither drain significant energy from the turbulence nor convert eddy motion of the turbulence on the outer scale to wave like motion. This preserves the diffusive effects needed for the large scale dynamo operation.

• Journal of Auto-vehicle Safety Association
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• v.9 no.4
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• pp.20-25
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• 2017

Dynamo based vehicle inspection device is end of line device for automobile industry. The device is utilized as implementing vehicle functionality inspection such as brake force, cruise control, kick-down acceleration, CAN inspection. As dynamo based inspection device is broadly adopted in automobile industry, the dynamic study is required to verify the vehicle test equipment reliability. This research recommends appropriate dynamic brake force inspection procedure and theoretical background for developed equipment. Dynamic characteristic of brake force implementation to roller is simplified. With simplified characteristics, the indirect brake force measurement strategy is developed and adopted. Comparison of each brake force result, the appropriate brake force inspection criterion is given.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.273-277
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• 2007

In case of the Hydraulic Turbine Dynamo operating for Waterpower Generation, it makes very huge and loud noises, and it influences bad effect physically as same as mentally to those people who are working inside of power plant, and brings the decline of an effective working efficiency. However, its evaluation method or measure about such noise reflects merely its physical attribute which is sensuous Loudness of the Noise itself, since the accumulation effect of Noise or the meaning connected with psychological response did not reflect, it is the actual state that a rational evaluation is unable to expect. Consequently, this Study has attempted to evaluate the Noise of Hydraulic Turbine Dynamo by analyzing the sound quality using Zwicker‘s Psychological Acoustic Parameter, after classification by its positions of the Noise occurring at Hydraulic Turbine Dynamo.

• Tribology and Lubricants
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• v.16 no.1
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• pp.33-38
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• 2000

Abstract- In this paper tribological characteristics of solid and liquid phase sintered W/C-35%Ni tappets were investigated. Three test methods were performed to investigate the wear and surface damage mechanism of sintered tappets. First, block-on-ring wear test was performed to investigate the wear characteristics under pure sliding condition. Second, simplified cam and tappet tests (called component wear test hereafter) were carried out to simulate the real contact history of cam and tappet. Also, after the test, contact surfaces were analyzed with scanning electron microscope to study the wear mechanism. As a final screening, engine dynamo tests were performed. Results showed that in the block on ring sliding wear test, solid phase sintered specimens showed superior wear resistance to liquid phase sintered specimens. The component wear tests and engine dynamo tests also showed the same results. Therefore, in these tests, solid phase sintered tappet material revealed superior wear resistant properties to liquid phase sintered one.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.4
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• pp.40-47
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• 2009

There are many kinds of simplifications and limitations in evaluating thermal performance of disc brake using the analytic technologies which were established before. But now new virtual test technology with several advanced analytic techniques is developed to evaluate the thermal performance without any possibility of great errors that used to happen for the time-consuming analysis. As a result, it was estimated that the virtual test technology could afford to replace the physical dynamo test since the reliability of virtual test technology was reasonably verified with the existing data measured in dynamo test.