• Geomechanics and Engineering
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• v.19 no.4
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• pp.353-360
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• 2019

The elastic modulus is an important parameter to characterize the property of rock. It is common knowledge that the strengths of rocks are significantly different under tension and compression. However, little attention has been paid to the bi-modularity of rock. To validate whether the rock elastic moduli in tension and compression are the same, Brazilian disc, direct tension and compression tests were conducted. A horizontal laser displacement meter and a pair of vertical and transverse strain gauges were applied. Four types of materials were tested, including three types of rock materials and one type of steel material. A comprehensive comparison of the elastic moduli based on different experimental results was presented, and a tension-compression anisotropy model was proposed to explain the experimental results. The results from this study indicate that the rock elastic modulus is different under tension and compression. The ratio of the rock elastic moduli under compression and tension ranges from 2 to 4. The rock tensile moduli from the strain data and displacement data are approximate. The elastic moduli from the Brazilian disc test are consistent with those from the uniaxial tension and compression tests. The Brazilian disc test is a convenient method for estimating the tensile and compressive moduli of rock materials.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.2
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• pp.17-22
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• 2009

Estimate method of cable tension forces can be classified into direct method and indirect method. Direct method is not accuracy and it has many restrictions. Therefore, in generally Indirect method, vibration method using natural frequency, has been applied to estimate the tension forces. In this study, cable tensions of recently constructed cable-stayed bridge are measured using string vibration method and this result comparing with result of multiple mode method. To put it brief, the error of string vibration method is not exceeding 2% under 7th mode. Specially third and 4th mode error is not exceeding 1%. safety.

• Korea-Australia Rheology Journal
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• v.13 no.3
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• pp.125-130
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• 2001

Block copolymers of PC-b-PMMA (polycarbonate-b-polymethylmethacrylate) and PC -b-SAN (polycarbonate-b-(styrene-c-acrylonitrile)), were examined as compatibilizers for blonds of PC with SAN copolymer. The average diameter of the dispersed particles was measured with an image analyser, and the interfacial properties of the blonds were analysed with an imbedded fiber retraction (IFR) technique. The average diameter of dispersed particles and interfacial tension of the PC/SAN blends reached a minimum value when the SAN copolymer contained about 24 wt% AN. Interfacial tension and particle size were further reduced by adding compatibilizer to the PC/SAN blends. PC-b-PMMA was more effective than PC-b-SAN as a compatibilizer in reducing the average diameter of the dispersed particles and interfacial tension of PC/SAN blend. A direct proportionality between the particle diameter and interfacial tension was also observed. The interfacial properties of the PC/SAN blends were optimized by adding a block copolymer and using an SAN copolymer that had minimum interaction energy with PC.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.423-426
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• 2001

In this paper a large scale direct tension test of plain concrete is represented. Two independently controlled actuators were used to ensure a homogeneous tensile field and to avoid secondary flexural stresses. Fracture energies evaluated by a classical prediction equation and this test are compared. The result indicated that the classical prediction equation is not adequate to predict the fracture energy of large sized specimens. From this test, it was determined that the fracture energy obtained from large scale direct tension tests is significantly higher than the one obtained in wedge splitting tests on laboratory sized specimens. But the tensile strength was about half the value determined from splitting tensile strength test with cylindrical specimens.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.10-13
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• 2011

A level set method is proposed to simulate the incompressible two-phase flow considering the effect of surface tension. For reinitialization of level set junction, a direct approach method is employed, instead of solving hyperbolic type equation. A mixed element is adopted, so that the continuity mid Navier-Stokes equations are solved by using the quadratic elements (six-node triangular element mid nine-node quadrilateral element), mid the level set function is solved by using the linear elements (three-node triangular element mid four-node quadrilateral element). In order to verify the accuracy mid robustness of the codes, the present methods are applied to a few benchmark problems. It is confirmed that the present results are in good qualitative mid quantitative agreements with the existing studies.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.83-88
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• 2004

Micro wires manufactured by the straightening progress are widely used in bio-medical and semi-conductor fields. In this study, we have developed a novel straightener which uses the direct heating method for straightening. In order to avoid the surface oxidization, during the heating process, we supplied the inert gas(Ar) and examined the effect of the gas flow rate. The effect of the tension and the current applied to the tungsten micro wires were thoroughly studied. From various experiments, it was found that when the tension is $500{\sim}600gf$ and the current is about 1.5A, we obtained higher straightness(${\approx}1{\mu}m/1000{\mu}m$) and roundness ($<{\pm}2{\mu}m/100{\mu}m$).

• Proceedings of the KSLP Conference
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• 1998.11a
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• pp.210-210
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• 1998

Vocal fold vibration is essentially the propagation of a mucosal wave, starting from the lower surface of the vocal fold. The mucosal upheaval (MU), where the mucosal wave starts and propagates upward, appears only when the vocal fold vibrates. We investigated the location of the mucosal upheaval in response In variations in vocal fold tension. Vibrations were elicited under three conditions: during bilateral thyroarytenoid (TA) muscle contraction, without TA muscle contraction and during vocal fold lengthening. TA muscle contraction was obtained by direct electrical stimulation of the muscle. The vocal fold was lengthened by cricothyroid (omitted)

• Journal of the Semiconductor & Display Technology
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• v.9 no.2
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• pp.103-109
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• 2010

An ink transfer is modeled and experimentally verified using roll-to-roll electric direct gravure printing process. The ink transfer model based on the physical mechanism for the maximum ink transfer rate is proposed, and experimented by the electric printing machine in FDRC for the relations of the maximum ink transfer rates to the printing pressure, the operating speed, the operating tension, the surface roughness of substrates, and the contact angle between substrate and silver ink. The free ink split coefficient and immobilized ink under the maximum ink transfer rate are calculated by the physical parameter in a printing process and contact angle between substrates and ink. Numerical simulations and experimental studies were carried out to verify performances of the proposed ink transfer model. Results showed that the proposed ink transfer model was effective for the prediction of the amount of transferred ink to the substrate in a direct gravure printing systems.

• Journal of ILASS-Korea
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• v.6 no.4
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• pp.22-30
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• 2001

The objective of this study is to develop the new equations for the calculation of higher heating values(HHVs) of reformed diesel fuels by ultrasonic treatment. Therefore, higher heating values of reformed diesel fuels by ultrasonic treatment are determined experimentally and calculated from their viscosity and surface tension measurements. The HHVs of the fuels are supposed to be a function of viscosity(Pa s) and surface tension(N/cm). The equations developed for the samples represent the correlation obtained by means of regression analysis. The HHVs calculated by developing new equations using viscosities showes the differences from the measured values ranging from -0.66 to 1.19 % and the correlation coefficient was -0.9411. The HHVs calculated by developing new equations using surface tensions showed the differences from the measured values ranging from -0.70 to 1.51 % and the correlation coefficient was 0.9999. The viscosity and the surface tension are characteristic properties of ultrasonic reformed diesel fuels for developing new formulae.

• International Journal of Highway Engineering
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• v.17 no.1
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• pp.43-49
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• 2015

PURPOSES : The objective of this study is to develop new pothole repair materials using polyurethane-modified asphalt binder, and to evaluate them relative to current pothole repair materials in order to improve the performance of repaired asphalt pavement. METHODS : In the laboratory, polyurethane-modified asphalt binder is developed, and then asphalt binder is added to produce pothole repair materials. In order to evaluate the properties of this new pothole repair material, both an indirect tension strength test and a direct tension strength test are performed to measure the material strength and bond strength, respectively. Additionally, the basic material properties are evaluated using the asphalt cold mix manual. The strength characteristics based on curing times are evaluated using a total of 7 types of materials (3 types of current materials, 2 types of new materials, and 2 types of moisture conditioned new materials). The indirect tension strength tests are conducted at 1, 2, 4, 8, 16, and 32 days of curing time. The bond strength between current HMA(Hot Mix Asphalt) and the new materials is evaluated by the direct tension strength test. RESULTS AND CONCLUSIONS : Overall, the new materials show better properties than current materials. Based on the test results, the new materials demonstrate less susceptibility to moisture, faster curing times, and an improved bond strength between HMA and the new materials. Therefore, the use of the new materials reported in this study may lead to enhanced performance of repairs made to asphalt pavement potholes.