• International Journal of Railway
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• v.1 no.4
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• pp.169-174
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• 2008

Experimental study has been conducted to clarify the internal and external pressure variation characteristics for KTX(Korea Train eXpress) passing through tunnel. Abrupt pressure variation gives rise to the ear-discomfort for passenger and fatigue for car body. In this study, the internal and external pressure variation are measured by using KTX real train experiment and on-board portable data acquisition system in Gyeongbu high speed commercial line. The tunnels from 200 m to 4000 m in length are chosen for the investigation of tunnel length effects. From the results of experiment, the internal pressure variation rate for all the test tunnels is lower than the standard criteria of 200 Pa/s. And, the critical tunnel lengths for pressure wave pattern are classified into 7 groups by using the theoretical L-t diagram analysis.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.3
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• pp.127-130
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• 1987

The Cavitation inception in oil hydraulic pipeline was investigated experimentally and numerically. In the experiment, negative pressures below -1 MPa (absolute pressure) were measured, associated with the transient flows in oil hydraulic pipeline. These experimental results show that the common hydraulic oil in the experimental pipeline withstands large tensions. The growth of a spherical bubble in a infinite volume of viscous compressible fluid due to a stepwise pressure drop was investigated to obtain the critical bubble radius. The calculated value of the critical bubble radius corresponding to the negative pressure measured in the experiment is so small that the premised condition about the bubble shape in the analysis is unsatisfactory. The physical significance of this calculated result implies the fact that there hardly exist free bubbles which can act as cavitation nuclei in the experimental pipeline.

• School Mathematics
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• v.15 no.2
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• pp.221-241
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• 2013

This study considers the experiment of Inhelder and Piaget(1963) in various aspects, and reveals the characteristics of the 'the formation of a critical mind', 'the transformation into the research question', 'the translation into the experiment', and 'the interpretation of the result of the experiment' in Piaget's genetic epistemology. According to these analyses, this study discusses the educational implications that the results of the Piaget's experiment support the education which raises the student's awareness.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.2
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• pp.168-173
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• 2014

The effect of critical minimum depth in the coastal region on storm surges was examined using a three-dimensional primitive equation model (POM). Case studies using numerical experiments in a small coastal bay in the southern sea of Korea (Hanam Bay) have examined the 'critical depth' (CD) that stabilizes the numerical calculations. Dependence of the CD of typhoon tracks and tidal components such as M2, S2, O1, and K1 were examined. The model results clearly demonstrated that the numerically unstable state of the calculation was caused by the coarse resolution of sea surface elevation.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.5
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• pp.551-558
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• 2011

To analyze the effect of wear of wheel profile on the running stability of rolling-stock, theoretical and experimental studies were conducted on the profiles used in conventional lines. In experiment using 1/5 scale model to verify the results of the theoretical analysis, the test results of the critical speed for worn wheel profile samples show similar trend. In case of the conical type wheel profile(Profile 40), the equivalent conicity is increased with flange wear. But in case of the arc type wheel profile(Profile 20h), the equivalent conicity is decreased with flange wear. And the critical speed of the bogie was inverse proportion to the equivalent conicity. It is shown that the variation of the critical speed with the wheel wear could be changed according to the design concept and wear pattern of wheel profile. Results of the theoretical and experimental studies are discussed here.

• Progress in Superconductivity and Cryogenics
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• v.15 no.1
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• pp.51-54
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• 2013

This paper deals with harmonic components of the voltage on high temperature superconducting wire carrying an alternating current. HTS wire is used to manufacture superconducting power applications carrying an alternating current. Typically, international standard, IEC 61788-3 is used for critical current measurement. Thus, it is not ideal that critical current criteria in dc are adapted to superconducting power devices to decide the operating current of the devices. In this paper, we confirmed odd harmonic voltage on HTS wires carrying an AC. The ratio between harmonic components and fundamental component can be significant clues to decide the critical current criteria for HTS wire and its power applications in AC circumstance.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.19-29
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• 2021

This paper presents the validation of the MCS code for critical safety analysis with burnup credit for the spent fuel casks. The validation process in this work considers five critical benchmark problem sets, which consist of total 80 critical experiments having MOX fuels from the International Criticality Safety Benchmark Evaluation Project (ICSBEP). The similarity analysis with the use of sensitivity and uncertainty tool TSUNAMI in SCALE was used to determine the applicable benchmark experiments corresponding to each spent fuel cask model and then the Upper Safety Limits (USLs) except for the isotopic validation were evaluated following the guidance from NUREG/CR-6698. The validation process in this work was also performed with the MCNP6 for comparison with the results using MCS calculations. The results of this work showed the consistence between MCS and MCNP6 for the MOX fueled criticality benchmarks, thus proving the reliability of the MCS calculations.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.91.2-91
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 1998.10a
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• pp.128-128
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• 1998

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.111.1-111
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• 2002