• International Journal of Highway Engineering
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• v.15 no.4
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• pp.95-105
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• 2013

PURPOSES: The purpose of this study is to research the influence of road traffic noise by road slope through the analysis of the field road traffic noise and determine consideration of road slope in the case of appling active noise cancellation. METHODS: This study measures vehicle's noise by the NCPX method at the three field sections such as uphill, downhill, and flatland. Total sound pressure and sound pressure level by the 1/3 octave band frequency are calculated through the raw field data. Total sound pressure level is compared by ANOVA test and T test statistically. The results obtained are compared in accordance with the road slope and the progress of the uphill section. RESULTS : The noise characteristic of early, medium, and last parts of uphill was found to be consistent when the vehicle was travelling uphill section. The result of statistical test, it was shown that total sound pressures are not different each other. According to the comparison by the geometry, sound pressure of the uphill section was higher than those of the flatland and downhill section in high frequency band. By the result of statistical test, total sound pressure are different according to geometry in the case of high vehicle speed. In the comparison result by road slope, each sound pressure level was found to be consistent in total frequency. However, total sound pressure proportionally increased according to road slope. CONCLUSIONS: It is found that the effect of road slope on noise generation was little in this experimental sites.

• Geomechanics and Engineering
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• v.11 no.6
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• pp.879-896
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• 2016

A new earth pressure equation considering the arching effect in $c-{\phi}$ soils was proposed for the accurate calculation of earth pressure on circular vertical shafts. The arching effect and the subsequent load recovery phenomenon occurring due to multi-step excavation were quantitatively investigated through laboratory tests. The new earth pressure equation was verified by comparing the test results with the earth pressures predicted by new equation in various soil conditions. Resulting from testing by using multi-step excavation, the arching effect and load recovery were clearly observed. The test results in $c-{\phi}$ soil showed that even a small amount of cohesion can cause the earth pressure to decrease significantly. Therefore, predicting earth pressure without considering such cohesion can lead to overestimation of earth pressure. The test results in various ground conditions demonstrated that the newly proposed equation, which enables consideration of cohesion as appropriate, is the most reliable equation for predicting earth pressure in both ${\phi}$ soil and $c-{\phi}$ soil. The comparison of the theoretical equations with the field data measured on a real construction site also highlighted the best-fitness of the theoretical equation in predicting earth pressure.

• Structural Engineering and Mechanics
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• v.70 no.4
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• pp.431-443
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• 2019

The present paper illustrates a numerical investigation on the failure behaviour of ring-stiffened cylinder subjected to external hydrostatic pressure. The published test data of steel welded ring-stiffened cylinder are surveyed and collected. Eight test models are chosen for the verification of the modelling and FE analyses procedures. The imperfection as the consequences of the fabrication processes, such as initial geometric deformation and residual stresses due to welding and cold forming, which reduced the ultimate strength, are simulated. The results show that the collapse pressure and failure mode predicted by the nonlinear FE analyses agree acceptably with the experimental results. In addition, the failure mode parameter obtained from the characteristic pressure such as interframe buckling pressure known as local buckling pressure, overall buckling pressure, and yield pressure are also examined through the collected data and shows a good correlation. A parametric study is then conducted to confirm the failure progression as the basic parameters such as the shell radius, thickness, overall length of the compartment, and stiffener spacing are varied.

• The KSFM Journal of Fluid Machinery
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• v.19 no.3
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• pp.53-56
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• 2016

In this study, experiments and finite element method analysis were used to determine the autofrettage pressure that is optimal and then maximizes the cycling life of Type3 composite cylinders used in self-contained breathing apparatus. For both approaches, the cylinders were pressurized at 100, 110, ${\ldots}$, 290 % of the test pressure, respectively. The stresses were computed by the FEM analysis; while the strains of cylinders were recorded and the failure modes were monitored during the cycling test. As a result, from the good agreements between the simulations and experiments, it was concluded that at least 70 % of the test pressure should be applied as the autofrettage pressure in order to takes visible effect on the cycling life, and 160 % of the test pressure induces the maximum cycling life and the desired failure mode.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.202-209
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• 2008

KSLV-1 2nd stage Kick Motor Nozzle was exposed to high temperature and pressure during the firing. Under the high pressure environment, Kick Motor Nozzle hydro-pressure test was done for verifying the structural safety of the nozzle. The differences with the KM hydro-pressure test [1] are that the real immerged heat resistance material is assembled and the throat heat resistance material is similar with the real one. The hydro-pressure tests were done for the two times of the 125 % of MEOP (975 psi) and the 153 % of the MEOP.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.3
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• pp.1-8
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• 2015

A ground hot-firing test(HFT) was accomplished to draw a correlation between the pressure oscillation intensity of combustion chamber and thrust response characteristics in a 70 N-class hydrazine thruster which has been developed recently. Monopropellant grade hydrazine was adopted as a propellant for the HFT, and combustion-chamber characteristic length, propellant injection pressure were applied as test parameters. It was confirmed that the decrease of thrust-chamber diameter and injection pressure augmented the pressure oscillation of stagnation chamber in the test condition specified, and the oscillation hampered the pulse response performance of test models.

• Geomechanics and Engineering
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• v.16 no.5
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• pp.547-558
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• 2018

Studies of soil dynamic properties in Malaysia are still very limited. This study aims to investigate the dynamic properties of two selected tropical residual soils (i.e., Sandy Clay and Sandy Silt) and a sand mining trail (Silty Sand) in Peninsular Malaysia using 1g shaking table test. The use of 1g shaking table test for soil dynamic testing is often constrained to large strain level and small confining pressure only. Three new experimental setups, namely large laminar shear box test (LLSBT), small chamber test with positive air pressure (SCT), and small sample test with suction (SSTS) are attempted with the aims of these experimental setups are capable of evaluating the dynamic properties of soils covering a wider range of shear strain and confining pressure. The details of each experimental setup are described explicitly in this paper. Experimental results show that the combined use of the LLSBT and SCT is capable of rendering soil dynamic properties covering a strain range of 0.017%-1.48% under confining pressures of 5-100 kPa. The studied tropical residual soils in Malaysia behaved neither as pure sand nor clay, but show a relatively good agreement with the dynamic properties of residual soils in Singapore. Effects of confining pressure and plasticity index on the studied tropical residual soils are found to be insignificant in this particular study.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.359-363
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• 2011

In this paper, the characteristic of pressures had been analyzed with a series of shapes that are pressure probes used in supersonic wind tunnel. When a performance of supersonic wind tunnel is evaluated, the Mach number is calculated by using the ratio of static pressure in test section wall to total pressure in settling chamber. Also the flow condition can be visualized by schlieren system. However a number of limitations exist to measure pressure of test section due to high speed and boundary layer effect. Therefore a specific pressure probe is needed for evaluating flow condition in test section at a various of positions. In the paper, experiments were conducted in terms of some pitot probes and the results were compared and analyzed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1016-1020
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• 2017

This study was conducted to develop a test facility that simulates the combustion instability that occurs in a real-scale liquid rocket combustor. A separate engine head with 3 injectors arranged in a row was designed/manufactured and verified through preliminary tests. The flow rate and spray pattern of the head were confirmed by the cold flow test. Next, propellant spray test and combustion test were carried out. A preliminary combustion test was carried out at 10 bar and the combustion chamber pressure was measured to be significantly lower than the target pressure. This is because it was a low pressure test, and it is expected to be resolved in the high pressure test in the future.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1416-1419
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• 2005

Design and manufacturing of plastic injection mold with cavity pressure/temperature sensors were performed in the present study for tensile test specimen. Standards of mold-base and tensile test specimen were used to design an injection molding system. Cavity pressure and temperature sensors were placed on the side of fixed platen of injection mold machine to prevent them from external impact damage. Injection molding experiments with variations of injection speed and melt temperature were performed and polycarbonate tensile specimens were prepared for the tensile test. It was shown that injection molding processing parameters can have effect on the mechanical properties of the plastic injection molded part.