• Proceedings of the KSME Conference
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• 2004.11a
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• pp.67-72
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• 2004

Fundamentally, slip displacement should be known to solve the problem related to the fretting wear. For this, methods for measuring the slip displacement range in the contact surface of the tube and the supports were introduced and analyzed in this study. Also the increment of the slip displacement during a cycle was calculated using the revised formulas. As a result, the slip displacement newly evaluated was much higher ($7{\sim}50$ times) than that previously evaluated especially in the case of the gap existence. This enables to explain the severe wear found when there was a gap between the tube and the supports.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.3
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• pp.1-5
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• 2000

This paper described about variance of optical and electrical characteristics on a fluorescent lamp according to tube shape by measuring electric field of positive column, temperature and luminance of tube w- all. Electric field calculation of several amps shows that the characteristics was not changed in positive column, though cathode fall length, and the values of temperature and luminance of tube wall, changes mush in cathode region.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.7
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• pp.595-601
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• 2001

We applied PIV method to obtain instantaneous and ensemble averaged velocity fields from the first row to the fifth row of a staggered tube bundle. The Reynolds number based on the tube diameter and the maximum velocity was set to be 4,000. Remarkably different natures are observed in the developing bundle flow. Such differences are depicted in the mean recirculating bubble length and the vorticity distributions. The jet-like flow seems to be a dominant feature after the second row and usually skew. However, the ensemble averaged fields show symmetric profiles and the flow characteristics between the third and fourth measuring planes are not so different. comparison between the PIV data and the RANS simulation yields severe disagreement in spite of the same Reynolds number. It can be explained that the distinct jet-like unsteady motions are not to be accounted in th steady numerical analysis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.1
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• pp.24-30
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• 1985

An experimental work to predict critical flow velocity to give whirling instability on staggered array tube banks model which is located in wind tunnel is presented. The critical flow velocity was obtained by measuring flow induced tube vibration on three tube array models having different pitch to diameter ratio as changing damping ratio and natural frequency of tube model. The obtained experimental results are directly compared with the numbers of other investigators and partly proved the truth of Blevin's new idea to predict critical flow velocity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2122-2126
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• 2007

A special PM-Tube(Photo Multiplier Tube) that is using the photoelectric effect has been designed and manufactured to measure the radiation energy of arc in a gas circuit breaker(GCB). The PM-Tube, LLG(liquid light guides), ND(neutral density) filter, and a model gas circuit breaker have been combined for the reception and the transmission of the light and a simplified synthetic test facility with the arc energy measuring system has been established. In the case of $SF_6$ gas pressure $5kg.f/cm^2$ and arc length 20mm, the radiation energy increases with the arc current but it tend to be saturated in the above 20kA. Under the arc current 20kA, the total radiation energy has the biggest value around 8kA and was not exceeded 40% of the total arc energy.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.5
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• pp.49-54
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• 2005

An experimental Investigation was performed to study the characteristics of Electro-Rheological fluid flow in a horizontal rectangular tube with or without D.C electric field control. First, the microscopic behavior of the ER suspension structure between rectangular tube brass electrodes for the stationary ER nut(i and flow of the ER fluid was investigated by flow visualization. The flow of the ER fluid between fluid rectangular tube was solved experimental using the constitutive equation for a Bingham fluid. ER fluid is made silicon oil mixed with $0.2wt\%$ starch having hydrous particles. Velocity distributions of the ER fluids were obtained by particle image velocimetry measuring those of the clusters using an image processing technique.

• Journal of the Korean Society for Heat Treatment
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• v.30 no.5
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• pp.207-214
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• 2017

In this study, failure behavior of piercing plug for seamless tube manufacturing process was studied. Three different kinds of passed piercing plugs (10, 90, 215 times) were prepared. The shape deformation of the passed piercing plugs was observed by 3D coordinate measuring machine, and the oxidized layer on the surface of piercing plug was observed by optical microscopy. The length reduction of piercing plug presented at 215 times passed plug. It was found that the oxidized layer consisted of outer scale, inner scale and internal oxidation layers, and the inner scale layer had vertical cracks, and interfaces had horizontal cracks. We proposed the failure mechanism of piercing plug during seamless tube manufacturing process based on the formation of vertical and horizontal crack.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.6
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• pp.561-569
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• 2000

Single phase and condensation heat transfer characteristics of ammonia in a horizontal tube have been investigated experimentally The horizontal test section is composed of smooth SUS316 tube for refrigerant flow, surrounding annulus for water flow, and temperature and Pressure measuring sensors. For single phase test, subcooled ammonia mass flux was varied from 320 to 501 kg/mrs and temperature was varied from 18 to $47^{\circ}C$. For condensation test, mass flux and saturation temperature were varied from 86 to 128 kg/$m^2$s and 34 to $47^{\circ}C$, respectively. The equations of Gnielinski Soliman et al., Traviss et at., Cavallini and Zecchin, Shah, Chen et al., Tandon et al., and Chilli and Anand were compared with the experimental data. New correlations are proposed based on the experimental results and the absolute mean deviation of the experimental data becomes 1.0% for single phase test and 4.9% for condensation test.

• Journal of the Korean Society of Visualization
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• v.1 no.2
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• pp.29-37
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• 2003

During the past five decades or so, the characteristics of turbulent swirling flow have been studied extensively because of its great technological and scientific importance. It is well known that the swirling flow improves heat transfer in duct flow. The reason for this is due to the effect of streamline curvature associated with the tangential velocity component. Although many studies have been carried out to investigate the characteristics of the swirling flow in a circular tube. The experimental methods for measuring the velocity components are by hot-wire or LDV (Laser-Doppler-Velocimetry) measuring single point velocity so far. The present study was aimed to analyse the flow characteristics of swirling flow such as time-mean velocity vector, local velocity turbulence intensity and turbulence kinetic energy by using PIV(Particle-Image Velocimetry). The experiment was carried out for four Reynold numbers $1.0\times10^{4}$, $1.5\times10^{4}$, $2.0\times10^{4}$ and $2.5\times10^{4}$ of the measuring area.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.3
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• pp.279-286
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• 2017

Korea government decides to build one hundred hydrogen refueling stations (HRS) until 2020 and tries to disseminate HRS and boosts HRS market in korea. Naepo HRS in chungnam province has been operated for last one full year of 2016 and recorded 2,520 times full charge for the hydrogen fuel cell powered vehicles and total 6,016 kg hydrogen fueling for the 25 units of hydrogen fuel cell powered vehicles. Raw fuel of hydrogen from tube trailer measured by pressure, converting into weight of hydrogen and shows 19.6% surplus with final charged weight by dispenser. This result is caused measuring errors. Measured charged errors between dispenser and Mass flow meter was determined 13.13%.