• Structural Engineering and Mechanics
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• v.75 no.5
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• pp.621-631
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• 2020

A laboratory experiment is conducted is to investigate the behaviour of a low-mass-ratio and high aspect ratio flexible cylinder under vortex-induced vibration (VIV). A flexible cylinder with aspect ratio of 100 and mass ratio of 1.17 is towed horizontally to generate uniform flow profile. The range of Reynolds number is from 1380 to 13800. Vibration amplitude, in-line and cross-flow frequency response, amplitude trajectory, mean tension variation and hydrodynamic force coefficients are analyzed based on the measurement from strain gauges, load cell and CCD camera. Experimental results indicate that broad-banded lock-in region is found for the cylinder with a small Strouhal number. The frequency switches in the present study indicates the change of the VIV phenomenon. The hydrodynamic force responses provide more understanding on the VIV of a low mass ratio cylinder.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.4
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• pp.227-233
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• 2014

Information presented in this study is intended to inform candidates as they prepare to design and structure the floatovoltaics solar power system. A developed floatovoltaics solar power generation results from the combination of PV plant technology and PV floating technology. This floating-based PV system is a new concept for PV development. The PV floating technology opens new opportunities to give value to unused areas so far while preserving valuable land for more adapted activities. Therefore the land-use conflicts are avoided and the environmental impact is minimized. Therefore the technology offers an interesting opportunity to regions facing on drought during summer time without any negative impact to the eco-system. This study describe the basic components of a floatovoltaics solar power system. A typical system consist of floating system and solar modules, a control device, rechargeable batteries, a load or device and the associated electrical connections. The floating system is specifically designed to keep all metallic components above water leaving only 100% recyclable, closed cell foam filled HDPE plastic floats in contact with the water. As the first case that can maximize the power generation efficiency of PV internationally, it is expected that this study will be utilized as a primary guide for future development of floating type PV system.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2006.06a
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• pp.97-100
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• 2006

A sensor and measuring system were implemented to measure both uroflow and urophonography signal during urination for diagnose the BPH(benign prostatic hypertrophy). The implemented system was composed of the uroflow sensor using the load-cell, the urophonography measurement sensor so as stethoscope type, pre-processing part for sensors signal detection, amplifier and filter, system control parts and PC measurement program. A simulator of the lower urinary system that is experimental equipment implemented for evaluates the developed system. The two signals were measured using implemented system and analyzed these signal by means of time domain and frequency domain for extraction of the characteristic parameter which can most effectively reflected by the occlusion of the lower urinary system. Furthermore two signals were measured and analyzed with the subject of 5 healthy adult for clinical application possibility of the implemented system. As a result, the most influence bandwidth of effect according to occlusion of the lower urinary system is $253{\sim}282Hz$ of the urophonography signal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.56-63
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• 2000

In this paper, we design new high performance ATM switch architectures based on a Generalized Shuffle network(GSN). The GSN is a distributed network topology with the number of nodes in O(N). To improve the throughput of the switch, a layering strategy called Weaved GSN(WGSN). WGSN has an additional connection links between switching elements which locate in the same position of adjacent GSNs. The analysis and simulation are performed under uniform and full load conditions, and the results show that the proposed switch has better throughput and cell loss performance when compared with other banyan-based switch architectures known so far.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.892-899
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• 2009

Reuse-partitioning is a simple technique that can be used to improve the capacity of a cellular system. In the previous researches, authors do not explain how a channel is selected and what happens when there is no channel available when a call arrives. Therefore, in this paper, we describe a simple channel selection procedure and analyze the performance of a system. The performance is presented in terms of the channel utilization and call blocking probability by varying offered load per cell. Our analytical results may be added in a realistic performance analysis of reuse-partitioning-based system.

• Journal of Sensor Science and Technology
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• v.13 no.6
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• pp.436-445
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• 2004

In this study, a uroflowmetry system was developed to detect a voiding symptom conveniently at home or hospital. A implemented hardware was composed of mechanism and system circuit part, the software was developed to process uroflow data, graph display, extraction of parameter, and evaluation of congregate rate so as to analysis obtaining uroflow data. The following experiment was performed to evaluate an ability of classification and fitness. The curve pattern of uroflow was classified into each symptom. Various parameters were calculated in the curve pattern of each uroflow as follows. The parameters are MFR, AFR, VOL, VT, and FT. A significant difference among parameters was examined by a statistical analysis for extracted parameters between normal and abnormal experimental group. The uroflow data with the various symptom was divided into normal and abnormal group using fuzzy classifier. The result of the fuzzy classification using MFR and AFR was superior by 91.23 % than grouping evaluation including VOL.

• Journal of Sensor Science and Technology
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• v.16 no.6
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• pp.413-418
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• 2007

Uroflowmetry is of great convenience to diagnose benign prostate hypertrophy common in aged men. The urinary flow rate is obtained by weight measurement using load cell, however, sensitive to impact noise. An alternative technique was recently proposed to measure hydraulic pressure instead of weight and demonstrated to introduce significantly reduced noise. In this paper, we described the measured diagnostic parameters between the weight and pressure measuring techniques in 10 normal men. The weight and pressure signals were simultaneously acquired during urination, converted into urine volumes, then differentiated to obtain flow rate signals, which showed very similar waveforms. Diagnostic parameters evaluated by pressure measuring technique were well correlated with the standard weight measuring technique (correlation coefficient > 0.99). Therefore, the new uroflowmetry based on hydraulic pressure measurement can provide accurate diagnostic parameters, which would be clinically valid.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.14 no.2
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• pp.1-8
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• 2006

Unsteady lift measurements were carried out in order to investigate the effects of phase difference and reduced frequency of a dragonfly-type model with two pairs of wing. A load-cell was employed to measure the lift generated by a plunging motion of the dragonfly-type model with the incidence angles of 0$^{circ}$. Experimental conditions are as follows: phase differences between fore- and hind-wings are 0$^{circ}$, 90$^{circ}$, 180$^{circ}$, and 270$^{circ}$, and reduced frequencies are 0.075, 0.15 and 0.225, respectively. The freestream velocity was 143 m/sec and corresponding chord Reynolds number was $3.4{\times}10^3$. The variation of phase-averaged lift coefficients during one cycle of the wing motion is presented. Results show that the total value of the positive lift coefficient during one cycle of the wing motion is the largest at the phase difference of 90$^{circ}$, and that the maximum lift coefficient and lift coefficient per unit of time increases with reduced frequency.

• Journal of the Korean Magnetics Society
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• v.4 no.4
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• pp.303-306
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• 1994

Fundamental characteristics of giant magnetostrictive alloy $Terfenol-D(Tb_{0.3}Dy_{0.7}Fe_{1.9~1.95})$ are rreasured and discussed on the application for actuators. The magnetostriction is measured by laser displacement rreasuring system and the applied compressive stress is measured by load cell. Magnetostrictions increased as the applied compressive stresses increased. When the stress is 7 MPa, the magnetostriction is 1000 ppm at 1500 Oe. As the stresses iocreased from 0 to 14 MPa, the magnetic fields for saturating the magnetostriction also increased. The temperature increased during the experiment is $0.3^{\circ}C$, so the thermal expansion is negligible in these experirrents. The feedback or temperature control function should be added for the precise position control actuator.

• Transactions of Materials Processing
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• v.27 no.1
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• pp.54-59
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• 2018

In connecting parts of a hydrogen fuel cell vehicle, since the rubber ring is permeable to hydrogen, it is necessary to use a metal sealing structure which ensures leakage stability. Finite element analysis was performed to verify the fitting characteristics of the metal sealing structure, which is used to connect the pipe to a high pressure hydrogen FCEV tank. Deformation shape, contact distance and axial load were compared experimentally and these values were in agreement with each other. In the contact surface, between the pipe and the fitting body, the stress at the edge of the contact surface was higher than the center point, which was considered to be a good characteristic in view point of the leakage. The location of the contact points has almost no change in the upper part of the fitting, but that of the lower parts move downward as the fastening amount increases. The contact pressure at the lower part is maintained at the same constant level.