• Journal of the Korean Wood Science and Technology
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• v.25 no.3
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• pp.96-104
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• 1997

The objective of this research project was to develop the wooden footpath block to reuse of wood waste. Some physical and mechanical properties of the wooden block such as water absorption, thickness swelling, modulus of rupture, internal bond, density profile and impact resistance were studied. Water absorption and thickness swelling of the wooden block were greatly reduced when the wooden block was pressed inside the forming device than by conventional hot pressing. Also, Modulus of rupture and internal bond of the wooden block were increased greatly when the pressing was completed inside the forming device. The density profile of the wooden block was improved up to 93.5%, minimum to average density ratio. The wooden block manufactured in this study have excellent physical and mechanical prperties in comparison with existing wood based materials. So, these wooden blocks are applicable to footpth block or other exterior members.

• Journal of the Korean Chemical Society
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• v.7 no.2
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• pp.144-152
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• 1963

A study was made of the effect of composition changes and particle size on appearance of raw bristol glazes fired at cones 5, 8, and 11. Alumina and silica, alkali and lime variations were made to get some of the more promising glazes determining maturing ranges, modulus of rupture, and other factors such as gloss, smoothness, opacity, eggshelling, crazing, pinholing and crawling for each glaze. Modulus of rupture was measured for the glazes fired at only cone 11.

• Journal of the Korean Ceramic Society
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• v.31 no.2
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• pp.194-200
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• 1994

Pitchstone(Volcanic ejecta) reacts with CaO in hot water and increases its sedimentary volume by forming Ca(OH)2 and calcium silicate hydrates. ALC was prepared from the various gelling and curing conditions using the ratio of pitchstone/CaO was 2(CaO/SiO2 mol ratio=0.81), and then the products, crystalline phases and physical properties of ALC with experimental conditions was investigated. The crystalline phase of tobermorite with laths and plate type and the porosity were increased, the thermal conductivity was decreased with increasing gelling temperature and time. But modulus of rupture has maximum value when gelling time was 2 hrs. Othwrwise the bulk density nearly unchanged with increasing curing temperature, but the modulus of rupture was increased.

• Proceedings of the Materials Research Society of Korea Conference
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• 1993.11a
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• pp.48-48
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• 1993

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.3
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• pp.882-890
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• 1996

Mechanical properties, including Young's modulus, residual stress and rupture strength, of a thermally evaporated gold film have been measured form a blister test. In a theoretical study, the priniple of minimum potential energy and that of virtual work have been applied to the pressurized circular membrane problem, and load-deflection relations have been derived for typical membrane deflection mode of spheroidal shape. In an experimental study, circular gold membranes of 4800 A-thickness and 3.5mm diameter were fabricated by the silicon electropolishing technique. Mecahnical properties of the thin gold films were deduced from the load-deflection curves obtained by the blister test, Young's moduli, obtianed from blister test, have been in the range of 45-70 GPa, while those of bulk gold have been in the range of 78-80 GPa. Residual stresses in the evaporated gold films have been measured as 28-110MPa in tension, The rupture strength of the gold film has turned out to be almost equal to that of dental gold alloy (310-380MPa). It has been demonstrated that the present specimen fabrication method and blister test apparatus have been effective for simultaneous measurement of Young's modulus, residual stress and repture strength of thin solid films. Especially, the electropolishing technique employed here has provided a simple and practical way to fabricate thin membranes in a circular or an arbitrary shape, which could not be obtained by the conventional anisotropic silicon mecromachining technique.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.185-191
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• 2010

Because the concrete crack that is the reason of the serviceability and durability degradation of concrete structure can be arisen from either the stress magnitude and gradient or other structural and material defects, the crack strength of concrete is hard to accurately evaluate. Especially, stress-state in concrete plate components such as rigid pavement and long span slab is biaxial flexure stress, and the flexural strength of those component may be different than the traditional rupture modulus of concrete subjected to uniaxial stress. In this study, an experimental investigation to assess of mechanical behavior under uniaxial and biaxial flexure stress is conducted and the proposed optimum specimen configuration is adopted. From the test, the modulus of rupture under uniaxial and biaxial stress are decreased as the size of aggregate or specimen is larger. And biaxial flexure strength of concrete specimens is varied from 39.5 to 99.2% as compared with that of uniaxial strength, and the biaxial strength of specimen with 20mm aggregate size is only 76% of uniaxial strength.

• Journal of the Korean Wood Science and Technology
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• v.44 no.3
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• pp.315-322
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• 2016

Block-glued glulam is a structural material that can be used as a construction member of a large-section wooden building, which is produced by edgewise bonding of two or more glulam beam elements. The edgewise bonding performance of the block-glued glulam was examined through delamination test and block shear strength test. According to the test results, the block-glued glulam that was manufactured with 1.5 MPa of compressive pressure after applying $500g/m^2$ of Resorcinol adhesive showed the best edgewise bonding performance. The block-glued glulam produced in a good edgewise bonding condition was compared with a control glulam with the same section modulus for bending strength performance. The modulus of elasticity (MOE) in bending was similar to that of the control glulam. The modulus of rupture (MOR) of the block-glued glulam was higher by 27% than that of the control glulam. No interfacial failure or cohesive failure were observed in the edgewise bonding layer.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.446-453
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• 2016

Structural capacity of water channel fabricated of concrete including blast furnace slag were investigated in this paper. An experimental study was consisted of materials test and structural test of concrete water channel. The mechanical properties of concrete including blast furnace slag were investigated. Ordinary Portland cement (OPC) was used as basic binder and the effect of the replacement of blast furnace slag for OPC was investigated. Experiments were performed to measure mechanical properties including compressive strength, elastic modulus and modulus of rupture. Test results show that the compressive strengths and modulus of ruptures of mixtures containing blast furnace slag were equivalent to those of OPC concrete. In addition, the structural capacity of concrete water channel with up to the replacement ratio of blast furnace slag of 45% was greater than the required strength in KS specification.

• Journal of Korea Foresty Energy
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• v.22 no.2
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• pp.60-68
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• 2003

In forest products industry, a variety of nondestructive evaluation techniques are now being used to assess the mechanical properties of structural lumber. Ultrasonic and longitudinal vibration technique are frequently used to assess the modulus of elasticity(MOE) of lumber. The objective of this research was to evaluate the MOE and modulus of rupture(MOR) of small-diameter of Larix log(Larix kaempferi Carr.), using these techniques. In this study, 50 small-diameter logs were nondestructiveively evaluated. The dynamic modulus of elasticity(Eu) of the logs was first evaluated, using an ultrasonic method. After ultrasonic tests, the logs were measured using a longitudinal vibration technique(Ev). Static bending test was then performed on the logs to obtain the static modulus of elasticity(Es) and modulus of rupture of these logs. In general, the dynamic MOE (Ev) of logs was closely co..elated with the stati, MOE for log. Based on the results of these experiments, it can be concluded that small-diameter Larix logs can be successfully evaluated by Ultrasonic and longitudinal vibration technique. The experimental results indicated that the ultrasonic technique is effective to the log, which contains many knots. The longitudinal vibration technique is effective to the log, in which many cracks are included.

• Journal of the Korean Society for Nondestructive Testing
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• v.9 no.2
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• pp.18-24
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• 1989

Computer-aided high frequency ultrasonic is applied to aluminum oxide(85w%, 94w%, 96w%, and 99w%) MOR(modulus of rupture) samples to evaluate mechanical properties such as density variation, pore content, elastic modulus, shear modulus, and poisson's ratio. Ultrasonic wave velocity and attenuation measurement techniques were used as an evaluator of such properties. Pulse-echo C-Scan images with different fate setting method using 50MHz center frequency 1 inch focal length transducer allows evaluation of density variation and pore content. Elastic modulus calculated with the relation of density and ultrasonic velocity. It shows good reliability as compared with resonance method. Sintered density variation of $0.025g/cm^{3}$, that is 0.6% of theoretical density in $Al_{2}O_{3}$ samples can be observed by ultrasonic velocity measurement. Attenuation measurement method qualitatively agree with 4-point fracture testing result concerning of porosity content.