• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.147-157
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• 2002

In this paper, the testing cell and the related theory far the interpretation of constant rate of strain (CRS) consolidation test results in case of radial drainage were developed. The proposed method makes it possible to evaluate consolidation characteristics of clayey soil rapidly and accurately. To investigate the application of the developed testing device and theory, CRS consolidation tests and incremental loading(IL) tests in radial drainage condition with remolded and undisturbed samples were performed. Comparisons of consolidation parameters from consolidation curves including coefficient of consolidation values show the applicability and the reliability of the suggested method. The experimental data were compared with additional vertical drainage CRS tests and IL tests, and then were analyzed considering the effect of the drainage direction. In addition, the effect of excess pore water pressure generated during CRS consolidation test was investigated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.38-43
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• 2002

A study on the test, design and fabrication of wind tunnel model for measurement of air load distribution on wing surfaces is presented. 447 pressure taps are installed normal to the wing surfaces, and measured by PSI-8400 system using total 8 ESPs modules installed in the model. The test was performed at 50 m/sec constant speed in the low speed wind tunnel of Agency for Defense Development. Tests were carried out to determine effects of angle of attack, angle of sideslip and flap and stores for the load distribution of wing. The test results in this paper can be applied to the design optimization of structure and validation of computational fluid dynamics.

• Tribology and Lubricants
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• v.40 no.1
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• pp.28-37
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• 2024

This paper presents the development of a squeeze film damper (SFD) test rig and experimental identification of the effects of clearance, damper length, journal eccentricity ratio, excitation amplitude, oil supply pressure, and oil flow rate on the damping coefficients of a test SFD with open ends and a central groove. Test data are compared with predictions from a simple model developed for short SFDs with open ends and a central groove. The test results show a significant decrease in the damping coefficient with increasing clearance and a dramatic increase with damper length, which are in good agreement with the simple model predictions. According to the simple model, the damping coefficient is inversely proportional to the cube of the clearance and directly proportional to the cube of the length. An increase in the journal eccentricity ratio results in a dramatic increase in the damping coefficient by as much as 15 times that of the concentric case, particularly at low excitation frequencies. By contrast, the measured damping coefficient remains almost constant with changes in the excitation amplitude and supply pressure, which are not major factors in the damper design. In general, the test data agree well with the simple model predictions, excluding cases that show increases in the SFD length and journal eccentricity, which indicate significant dependency on the excitation frequency.

• Proceedings of the Korean Printing Society Conference
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• 2001.06a
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• pp.135-140
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• 2001

Laboratory test method which determines the emulsification rate of dampening solution and ink has been described In lithography using the mutual repellence of oil and water, the emulsification is produced by dispersion of dampening water and ink because of the printing pressure on a practical press. Rheological properties of Ink-Water balance are the important factors in lithographic printing. The emulsification theory and laboratory test method deduced from Surland and Kim. It is shown that the emulfisication curves relate to the rates of change in the emulsifide ink\`s flow properties, to the shear stability of the emulsion formed To study on the factors determining the emulsion velocity, we have measured water pickup and calculated emulsification velocity constant \`k\` and activation energy.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.159-162
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• 2011

The hot-firing tests of a subscale gas generator were successfully performed to investigate the effect of injector shape variation on its discharge coefficient. The test results showed that discharge coefficients of fuel and liquid oxygen injectors remained nearly constant irrespective of the mixture ratio or the chamber pressure. In all experimental conditions, the combustion instability was not observed.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1095-1099
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• 2008

Critical state theory involves two state boundary surface. One is Roscoe surface and the other is Hvorslev surface. The shape of these boundary surface was changed because of several parameters : Critical state constant(M), spacing ratio (r) and critical state pore pressure coefficient($\wedge$). As these constants make difference to each model and the way of solution, they may affect the shape of state boundary surface. Specially, spacing ratio (r) is important. On this study, triaxial compression test was performed using remolded weathered mudstone soil and investigated variation of state boundary surface because of spacing ratio. In the results of prediction, critical state point was located highly and the shape of boundary surface was changed more tightly curve as decreasing spacing ratio.

• Korea-Australia Rheology Journal
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• v.16 no.4
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• pp.219-226
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• 2004

In this study the deformation of liquid-air interface of Newtonian or Boger fluids filled between two par­allel-plates geometry was investigated when two surfaces were separated at a constant speed. The interface between the fluid and air showed either stable or unstable deformation depending on experimental con­ditions. Repeated experiments for a wide range of experimental conditions revealed that the deformation mode could be classified into three types: 'stable region', 'fingering' and 'cavitation'. The experimental condition for the mode of deformation was plotted in a capillary number vs. Deborah number phase plane. It has been found that the elasticity of Boger fluids destabilize the interface deformation. On the other hand, the elasticity suppresses the formation and growth of cavities.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.69-72
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• 2003

The purpose of this study is the development of hybrid horizontal electrokinetic(EK) remediation system on rifle range soil under unsaturated conditions. In order to remediate soil polluted by multi-species heavy metals, in pi]of scale, a series of EK remediation tests are carried out. PVC and PDB(Plastic Drain Board) electrode systems that connected with the power supply of constant voltage and vacuum pressure of 0.5kgf/$\textrm{cm}^2$ are installed, The test results showed that the pH distribution in the sample is below 8, which is maintained until the test is finished, because of the injection of flushing solution. The final concentration, which is normalized by initial concentration, is ranged about 50 to 90%.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.73-76
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• 2011

The hot-firing tests of a subscale gas generator were successfully performed to investigate the effect of injector shape variation on discharge coefficients. The test results showed that discharge coefficients of fuel and liquid oxygen injectors remained nearly constant irrespective of variations of a mixture ratio and a chamber pressure. Especially, the discharge coefficient of the liquid oxygen injector was largely increased compared to the previous works.

• Korean Journal of Materials Research
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• v.15 no.4
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• pp.224-232
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• 2005

Dry sliding wear behavior of electro-pressure sintered Fe-Ni and Co-Fe-Ni compacts was investigated. Pin-on-disk wear tests were performed on the sintered Fe-Ni, Co-Fe-Ni disk specimens against alumina $(Al_2O_3)$ and silica $(SiO_2)$ ball counterparts at various loads ranging from 3N to 12N. A constant sliding speed of 0.1m/sec was employed. Wear rate was calculated by dividing the weight loss measured after the test by specific gravity and sliding distance. Worn surfaces and cross sections of them were examined by a scanning electron microscopy, and wear mechanism of the compacts was investigated. Wear characteristics of the compacts were discussed as a function of composition of the compacts. Relationship between the wear rate and mechancial properties of the compact was explored, and effects of the oxide layer that was formed on wearing surface of the compacts on the wear were also studied.