• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.813-818
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• 2009

Shear properties of plastic bottle film/plastic bottle film and plastic bottle film/granitic soil which were evaluated from static friction tests. The monotonic shear experiments were performed by using an tilt table apparatus and large direct shear device. The test results showed that the friction angle of each interface and the interface depended on the amount of normal stress, the type of the interface used. Therefore, the testing method should be determined carefully by considering the type of loads and normal stress expected in the field with using the materials installed in the site.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.5
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• pp.9-16
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• 2012

In this study, the effect of metakaoline and silica fume on the bond performances of structural polyvinyl alcohol (PVA) fiber in cement mortar, including bond strength, interface toughness, and microstructure analysis are presented. Metakaoline and silica fume contents ranging from 0 % to 15 % are used in the mix proportions. Pullout tests are conducted to measure the bond performance of PVA fiber from cement mortar. Test results showed the incorporation of metakaoline and silica fume can effectively enhance the PVA fiber-cement mortar interfacial properties. Bond strength and interface toughness increased with metakaoline and silica fume content up to 10 % in cement mortar and decreased when the metakaoline and silica fume content reached 15 %. The microstructural observation confirms the findings on the interface bond mechanism drawn from the fiber pullout test results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12
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• pp.1142-1149
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• 2003

The strength and characteristics of the soldering interface of the power semiconductor chip in a power module has been firstly surveyed by the peel strength measurement method. A power module is combined with several power chips which generally has 30∼400$\textrm{mm}^2$ chip area to allow several tens or bigger amps in current rating, so that the traditional methods for interface characterization like shear test could not be applied to high power module. In this study power diode modules were fabricated by using lead-tin solder with 10${\times}$10$\textrm{mm}^2$ or 7${\times}$7$\textrm{mm}^2$ soldering interface. The peel strengths of soldered interfaces were measured and then the microscopic investigation on the fractured surfaces were followed. The peel test indicated that the crack propagated either through the bulk of the soft lead-tin solder which has 55-60 kgf/cm peel strength or along the interface between the solder and the plated nickel layer which has much lower 22 kgf/cm strength. This study showed that the peel test would be a useful method to quantify the solderability as well as to recognize which is the worst interface or the softest material in a power module with a large soldering area.

• Geomechanics and Engineering
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• v.14 no.4
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• pp.387-398
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• 2018

The present study evaluates the interface shear strength between sand and different construction materials, namely steel and concrete, using direct shear test apparatus. The influence of surface roughness, mean size of sand particles, relative density of sand and size of the direct shear box on the interface shear behavior of sand with steel and concrete has been investigated. Test results show that the surface roughness of the construction materials significantly influences the interface shear strength. The peak and residual interface friction angles increase rapidly up to a particular value of surface roughness (critical surface roughness), beyond which the effect becomes negligible. At critical surface roughness, the peak and residual friction angles of the interfaces are 85-92% of the peak and residual internal friction angles of the sand. The particle size of sand (for morphologically identical sands) significantly influences the value of critical surface roughness. For the different roughness considered in the present study, both the peak and residual interaction coefficients lie in the range of 0.3-1. Moreover, the peak and residual interaction coefficients for all the interfaces considered are nearly identical, irrespective of the size of the direct shear box. The constitutive modeling of different interfaces followed the experimental investigation and it successfully predicted the pre-peak, peak and post peak interface shear response with reasonable accuracy. Moreover, the predicted stress-displacement relationship of different interfaces is in good agreement with the experimental results. The findings of the present study may also be applicable to other non-yielding interfaces having a similar range of roughness and sand properties.

• Magazine of the Korean Society of Agricultural Engineers
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• v.33 no.2
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• pp.82-93
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• 1991

The objective of this paper is to show that the soil-geotextile interaction needs to he addressed in addition to the usual tensile and modulus properties when the geotextile is being designed for a specific application. The soil-geotextile interaction can be directly assessed by standard direct shear test. The data presented here show that the shear strength paramaters describing the soil-geotextile interface can he greatly influenced by the type of the geotextile. In this investigation, we examined nine different geotextiles of varying construction and surface textures with two standard soil, under five loading conditions, and compared the shear strength and the frictional resistance with the corresponding values of soil itself The following conclusions were drawned from this study. 1. The shear stress-strain curve shows that there are the residual shear stresses at the soil-geotextile interface. Because of the hydraulic gradient between the soil and the geotextile, the excessive pore water can migrate into the geotextile and among the filaments and dissipate through the soil-geotextile interface. 2. The shear strength of the soil-geotextile interface is affected by the moisture content of the soil. At moisture content lower than the optimum water content of the Proctor compaction test, the shear strength of the soil-geotextile interface is greater. 3. The type and surface roughness of the geotextile have the greatest influence on the interface friction angle between the soil and the geotextile.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.153-157
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• 1989

In this paper, a new method of Eye Movement Pattern Encoding (EMPE) which is based on electrooculography(EOG) was suggested for the purpose of effective communication between man and machine, instead of Point-Of-Regard-Selection (PORS) method. Also, ocular interface is designed and the typing aid, eye-pattern writer, was constructed for the test of theoretical validity and its practical aspect. Effect of eye fatigue on the performance of ocular interface was quantified through fatigue test.

• Tribology and Lubricants
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• v.17 no.1
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• pp.40-55
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• 2001

Acoustic emission(AE) signal has been widely utilized to monitor the interaction at the head/disk interface. In this work the relationship between the AE signal and the state of contact between the slider and the disk is presented. Results of the FFT(Fast Fourier Transform) analyses of the AE signal could be used to better understand the interfacial interaction. Also, it was found that wear particles affect the AE signal. Therefore, the signal can be used to monitor the wear particle presence at the interface.

• Geomechanics and Engineering
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• v.23 no.1
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• pp.39-50
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• 2020

In order to understand the shear mechanical properties of the interface between clay and structure and better serve the practical engineering projects, it is critical to conduct shear tests on the clay-structure interface. In this work, the direct shear test of clay-concrete slab with different joint roughness coefficient (JRC) of the interface and different normal stress is performed in the laboratory. Our experimental results show that (1) shear strength of the interface between clay and structure is greatly affected by the change of normal stress under the same condition of JRC and shear stress of the interface gradually increases with increasing normal stress; (2) there is a critical value JRC_cr in the roughness coefficient of the interface; (3) the relationship between shear strength and normal stress can be described by the Mohr Coulomb failure criterion, and the cohesion and friction angle of the interface under different roughness conditions can be calculated accordingly. We find that there also exists a critical value JRC_cr for cohesion and the cohesion of the interface increases first and then decreases as JRC increases. Moreover, the friction angle of the interface fluctuates with the change of JRC and it is always smaller than the internal friction angle of clay used in this experiment; (4) the failure type of the interface of the clay-concrete slab is type I sliding failure and does not change with varying JRC when the normal stress is small enough. When the normal stress increases to a certain extent, the failure type of the interface will gradually change from shear failure to type II sliding failure with the increment of JRC.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.2
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• pp.165-172
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• 2010

Treated sewage could enable growth by providing key nutrients or seeding the sediments with enterococci strains that can grow in the environment. This study is to test the hypothesis that the flux of bacteria into the water column is rate-limited by the transfer of bacteria across the sediment/water interface. Two conceptual models are derived for the transfer of bacteria to the water column from the sediment/water interface: convective diffusion of isolated bacteria and resuspension of particle-associated bacteria. The model predictions are directly tested together with field measurements of bacteria and sediment in an effluent-dominated stream where high concentrations of enterococci in this stream originate primarily from growth of the bacteria in stream sediments. The results reveal that high concentrations of enterococci in this stream are transported primarily by resuspension of particle-associated bacteria accumulated at the sediment/water interface, either in the form of bacterial aggregates or in the form of inorganic particles.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.655-659
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• 1997

The analysis of cracks at the interface between dissimilar materilar has received a great deal of attention in recent years. In this paper we conducted the static tensile test for the aluminum bonded single lap-joint with the interface edge crack. Comparing this results, that is ultimate load and strain value of aluminum adherend by strain gauge with the fracture mechanics parameters, compliance and stress intensity factors acquied from the boundary element analysis, we concluded that there are critical value of crack length to provoke the interface fracture.