• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.589-596
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• 2002

In this study, static pile load tests with load transfer measurement were accomplished in the field. Yield pile capacity (or ultimate pile capacity) determined by load-settlement-time relationship was determined and axial load transfer behavior was analyzed. In the test for the four test piles were behaved as end bearing pile but ratios of skin friction to total pile capacity were 27%∼33%.

• Journal of Power Electronics
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• v.17 no.3
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• pp.641-652
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• 2017

This paper proposes a cost-effective topology to drive a three-phase open-end load based on a five-leg indirect matrix converter (IMC) and a space vector modulation (SVM) method. By sharing an inverter leg with two load terminals, the proposed topology can reduce the number of power switches when compared to topologies based on a direct matrix converter or a six-leg IMC. The new SVM method uses only the active vectors that do not produce common-mode voltage (CMV), which results in zero CMV across the load phase and significantly reduces the peak value of the CMV at the load terminal. Furthermore, the proposed drive system can increase the voltage transfer ratio up to 1.5 and provide a superior performance in terms of an output line-to-line voltage with a three-level pulse-width modulation waveform. Simulation and experimental results are given to verify the effectiveness of the proposed topology and the new SVM method.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.2
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• pp.85-92
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• 2000

30 kVA rotating-field type Super-Conducting Generator is built and tested with intensive FE(Finite Element) analysis. The generator is driven by VVVF inverter-fed induction motor. Open Circuit Characteristic(OCC) and Short Circuit Characteristic(SCC) are presented in this paper. Also, the test result under the light load(up to 3.6 kW) are given. From the design stage, 2-D FE analysis coupled with the external circuit has been performed. The external circuit includes the end winding resistance and reactance as well as two dampers. When compared with the test data, the FE analysis results show a very good agreement.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.161-166
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• 2004

Research for deposits in Nakdong eatuary that research about Nakdong eatuary's sediment flows out in Nakdong-kang so far had been progressed but research about deposits that is flowed in open sea is insufficient. Observed Nakdong eatuary's characteristic of sediment transfer through observation during the second during Buteo 20 days on February 6, 2004 in this research Resuspension bed load Flux appeared high the first result St.4 point and St.5 point. St.4 branch had much bed load amount that is flowed in the east, and bed load that St.5 branch is flowed in the south appeared much Tendency such as the first showed in the second result, but compare with the first result and St.5 branch had much bed load that is transfer in end. Bed load that is transfer in observation result Nakdong river was less. As this, can know that amount of sediment that is transfer in open sea more than deposits that is transfer in Nakdong river is much Is expected to exert effect that deposits that is transfer in open sea is high in Nakdong estuary's topography change. Specially, observation result is expected that Nakdong estuary's deposition tendency becomes Jinwoodo southern and Shinho southern.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.2
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• pp.187-192
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• 2009

A snap ring is a kind of metal spring with open ends which can be installed into a groove to prevent lateral movement. In this study a nonlinear finite element analysis model is developed to simulate the fastening process of a snap ring connecting the constant velocity joint and the transmission. Insert load, disengage load and breakage are three important issues. They are analyzed using the developed model. The load histories of simulations are similar to those of tests and the differences of maximum load are around 10%. Bending of the entire ring and unfolding of the end section are major contributors of the fastening load. The load variations caused by the angular position of spline tooth are about 50%. Breakage is highly sensitive to the position of a snap ring.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1140-1147
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• 2010

To find the soil plug of steel piles shaped by jet grouting, 4 blocks of cement milk with cube of 1.2m were made. 4 open-ended steel piles on the blocks were rested. The inner end part of 2 the piles was not reinforced. Cement milk 65%(SIG-1) and 100%(RJP-1) were filled into the block and height of 4.2 times of inner the pile diameter respectively. And the other the piles were welded 2 steel ring. The filling of the cement milk was an equal method as before(SIG-2 and RJP-2). Also the strain gauges were installed and the static pile load tests were done at the piles all. As a result, list in great order for effect of soil plug was (1)SIG-1, (2)SIG-2, (3)RJP-1, (4)RJP-2. This is because of strength and filling height of cement milk. And the higher the strength is, the greater the confining coefficient is.

• Journal of the Korean GEO-environmental Society
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• v.9 no.5
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• pp.45-52
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• 2008

The present study has extended OpenSees, which is an open-source software framework DOS program for developing applications to idealize geotechnical and structural problems, for the static analysis of axial load capacity and settlement of single piles in MS Windows environment. The Windows version of OpenSees as improved by this study has enhanced the DOS version from a general purpose software program to a special purpose program for driven and bored pile analysis with additional features of pre-processing and post-processing and a user friendly graphical interface. The method used in the load capacity analysis is the numerical methods based on load transfer functions combined with finite elements. The use of empirical nonlinear T-z and Q-z load transfer curves to model soil-pile interaction in skin friction and end bearing, respectively, has been shown to capture the nonlinear soil-pile response under settlement due to load. Validation studies have shown the static load capacity and settlement predictions implemented in this study are in fair agreement with reference data from the static loading tests.

• Geotechnical Engineering
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• v.5 no.4
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• pp.27-36
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• 1989

Load tests are executed on instrumented model piles to evaluate the magnitudes of soil plugging resistances mobilized at open-end pile tips. The plugging resistances are calculated by some existing methods, which are compared with observation. A couple of the methods are found to give good results. A new computational method to predict the plugging resistance is proposed in this paper, which also gives fairly close prodiction to the measurement, and is much simpler than the other computational methods.

• Progress in Superconductivity and Cryogenics
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• v.23 no.1
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• pp.1-6
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• 2021

Thermoacoustic oscillations (TAOs) could be often observed in liquid helium cryogenic system especially in half-open tubes. These tubes have closed warm end (300K) and open cold end (usually 4.4K). This phenomenon significantly induces additional heat load to cryogenic system and other undesirable effects. This work focuses on using computational fluid dynamics (CFD) method to study TAOs in liquid helium. The calculated physical model, numerical scheme and algorithm, and wall boundary conditions were introduced. The simulation results of onset process of thermoacoustic oscillations were presented and analyzed. In addition, other important characteristics including phase relation and frequency were studied. Moreover, comparisons between experiments and the CFD simulations were made, which demonstrated thevalidity of CFD simulation. CFD simulation can give us a better understanding of onset mechanism of TAOs and nonlinear characteristics in liquid helium cryogenic system.

• Journal of Ocean Engineering and Technology
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• v.35 no.1
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• pp.59-74
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• 2021

To validate the fire safety assessment of structures, many structural experiments under fire load have been conducted. However, most of these experiments were conducted in restricted environments, such as inside a furnace, and experiments were seldom carried out in open space. In this study, an experimental study on H-beams, frequently used as structural reinforcements, was carried out for validating the thermal-structural analysis method under development. A 1.8 MW burner fire was adopted with each end of the H-beam fixed without a mechanical load. Gas temperature, steel surface temperature, and displacements were then measured. During the experiment, gas and steel temperatures were obtained at 9 and 17 points near the H-beam, respectively. In addition, the vertical and horizontal displacements of the H-beam under fire load at 6 points were obtained. Furthermore, it was verified that the stable displacement measurements via the contact and non-contact methods were feasible in harsh environments where flames and smoke were both present.