• Journal of the Korean Wood Science and Technology
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• v.24 no.1
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• pp.95-99
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• 1996

The bending and compression strength properties of two types Rhus verniciflua specimens, which made of no heat-treated wood and heat-treated wood for urushiol extraction, were measured. The heat-treated specimens were finger-jointed with either resorcinol-phenol or polyurethane resin adhesives, and the vertical type bending strength property was also measured in these specimens. The results obtained are as follows ; 1. The correlation coefficient between the compression strength and specific gravity in the specimens of no heat-treated and heat-treated wood was high. However there was no difference in compression strength property as affected by heat treatment. 2 The correlation coefficient between the bending strength and specific gravity in the specimens of no heat-treated and heat-treated wood was also high. However, there was no difference in bending strength property as affected by heat treatment. 3 The bending test showed high correlation between modulus of elasticity and modulus of rupture for the specimens made of no heat-treated and heat-treated wood. However, there was no difference in bending strength property between the specimens made of heat-treated and no heat-treated wood. 4. The efficiencies of bending strength test on the finger-jointed specimens of heat-treated wood with resorcinol-phenol and polyurethane resin adhesives were 0.85, 0.81. respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.929-934
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• 2001

This study aimed to examine the cause of latent hydraulic property manifestation of ground granulated blast-furnace slag(GGBFS) using different alkali activators in pH, type and quantity. According to the experimental result, the higher pH value accelerated lastly latent hydraulic property and the early stage strength of GCBFS was ranked as activators with the higher pH, in an order of NaOH, $Ca(OH)_{2}$ and $Na_{2}$$Co_{3}$. Also, NaOH had accelerated latent hydraulic property of GGBFS, which had 40~50% of the 3 and 7 days compressive strength of base mortar in case of using 10% of powder-weight. In the case of 30% of GGBFS substitution with annexing 2.5% $Ca(OH)_{2}$, the compressive strength on the 3 and 7 days of the early-age, was increased to 5~10% than that of the same admixture with no activator. With annexing 5.0% $Ca(OH)_{2}$, the strength was increased to 10~20%. Although activator NaOH was effective on the manifestation of latent hydraulic property, it caused cement mortar compressive strength decrease by enlarging pore diameter.

• Corrosion Science and Technology
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• v.17 no.2
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• pp.81-89
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• 2018

In this study, the effect of Nb alloying element on the corrosion fatigue properties of high strength steel is investigated by conducting fatigue experiments under corrosive condition and hydrogen induced condition, potentiodynamic polarization test, tensile test and surface analyses. Nb element is added to enhance the mechanical property of medium carbon steel. This element forms MX-type phases such as carbides and nitrides which are playing an important role in the grain refinement. The grain refinement is one of the effective way to improve mechanical property because both tensile strength and toughness can be improved at the same time. However, MX-type phase precipitates can be a susceptible site to localized corrosion in corrosive environment due to the potential difference between matrix and precipitate. The obtained results showed that Nb-added steel improved corrosion fatigue property by grain refinement. However, it is degraded for hydrogen-induced fatigue property due to Nb, Ti-inclusions acting as a stronger trap.

• KIEAE Journal
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• v.9 no.2
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• pp.65-71
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• 2009

Results from tests for what mixing rate of soil and sand is proper for the rammed earth and for how much additives are optimum are as under. 1) In the test to evaluate what mixing rate of soil and sand is desirable, peptizing property and surface sticking rate are found similar in its degree, but compression strength is found most stable when the ratio of soil and sand mixing shows 30:70 which indicates the best mixing rate of soil and sand. 2) In a test to add hydrated lime, compression strength, peptizing property, and surface sticking rate are found best when the mixing rate of soil and sand shows 23:7. 3) In a test to add sea weeds, the peptizing property goes down at 75% of sea weeds input a little bit more than at 100%, but compression strength shows best at 75% which is thought to be the best rate. 4) In a drop test, more soil powder mixed, the sticking strength gets better and more sands are contained, the sticking strength gets far worse to be scattered in powder type. 5) As concluding all results mentioned in the above item, the most desirable mixing rate of soil, sand, and hydrated lime is found to be 23:7:70 for the rammed earth where compression strength, peptizing property, and surface sticking rate are best.

• Journal of the Korean Ceramic Society
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• v.29 no.11
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• pp.893-899
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• 1992

Composite specimens, which are composed MDF cement of HAC-PVA system were prepared by adding carbon fiber, hydrated silica and SiC powder, and we studied effect of additives on the flexural strength of the composites. All of additives is effective in the improvement of flexural strength of the composite specimens. The size of average pore diameter in the specimens which have high flexural strength property was small. Specimen mixed with hydrated silica was effective in the particle compact property. Flexural strength of carbon fiber reinforced MDF cement composites were improved because of crack deflection of carbon fiber in cementitious matrix.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.34-35
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• 2015

The purpose of this study is to investigate the compressive strength property of concrete with Ground granulated blast furnace slag(GBFS) using wash water from recycled aggregate. When GBFS is reacted with water, it doesn't happen to hydraulic reaction but GBFS becomes latent hydraulic property in alkaline environment. For this reason, if it is possible to use wash water from recycled coarse aggregate as mixture water, GBFS have the advantage of early strength due to effect of activation. We investigated the compressive strength properties of GBFS concrete using wash water from recycled aggregate. According to the experimentation result, ICP-OES showed wash water from recycled coarse aggregate has a high alkali value of pH of 12. Also, compressive strength in early age using wash water can be improved as an activation.

• Corrosion Science and Technology
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• v.4 no.2
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• pp.39-44
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• 2005

The purpose of this work is to understand the effect of Mo addition on SSC susceptibility of high strength low alloy steels in terms of microstructure and corrosion property. Materials used in this study are high strength low alloy (HSLA) steels with carbon content of 0.04wt% and Mo content varying from 0.1 to 0.3wt%. The corrosion property of steels was evaluated by immersion test in NACE-TM01-77 solution A and by analyzing the growth behavior of surface corrosion products. SSC resistance of steels was evaluated using constant load test. Electrochemical test was performed to investigate initial corrosion rate. Addition of Mo increased corrosion rate of steels by enhancing the porosity of surface corrosion products. However, corrosion rate was not directly related to SSC susceptibility of steels.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.245-250
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• 1998

The Elastic modulus depends on the elastic property of composition materials, the gravity of aggregate, the bond strength of binder, the usage and quantity of admixture, curing and measuring method, etc. Accordingly, the aim of this study, by manufacturing concrete of practical high strength range(600~ 1000kg/$\textrm{cm}^2$) with the specific cement and mineral admixtures, is to compare elastic modulus with the existing equations and also to estimate elastic property of use materials. As a result, it could be confirmed that the existing equations which were proposed by the ACI 363, CEB-FIP Code, and New-RC have a tendency to the overestimation in general. However, it could be confirmed that the KCI-96 and Norwegian NS 3473 equations are closed to measuring results, and that the elastic modulus property have a different tendency due to types of cements.

• Journal of Technologic Dentistry
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• v.35 no.2
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• pp.113-120
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• 2013

Purpose: This study was to observe surface property and bonding strength according to composition of Ni-Cr alloy for porcelain fused to metal crown. The two kinds of Ni-Cr alloy with different composition ratio of parent metal were observed general properties and chemical properties of each alloy surface and measured the shear bonding strength between ceramic and each alloys. The aim of study was to suggest the material for design of parent metal's composition ratio to development of alloy for porcelain fused to metal crown. Methods: The two kinds of alloy as test specimen was Ni(71wt.%)-Cr(12wt.%) and Ni(63wt.%)-Cr(23wt.%) alloy. The oxide on surface was observed by SEM and EDX. And the shear test was performed by MTS. Results: The surface property and oxide characteristic analysis of oxide layer, weight percentage of Element O within $Ni_{71}Cr_{12}$ alloy measured 12.74wt.%, but $Ni_{63}Cr_{23}$ alloy was measured 15.91wt.%. And the maximum shear bonding strength was measured 106.14MPa between $Ni_{71}Cr_{12}$ alloy and vintage halo (VV group). Conclusion: The surface property and oxide characteristic of $Ni_{71}Cr_{12}$ alloy was similar to $Ni_{63}Cr_{23}$ alloy. And VV group has the strongest shear bonding strength.

• Korean Journal of Applied Biomechanics
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• v.22 no.2
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• pp.237-242
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• 2012

The purpose of this study was (a) to develop carbon nanotube-based shock absorbers for reducing potentially harmful impact forces and excessive foot pronation, and (b) to briefly determine how the effects of carbon nanotube-based shock absorbers on biomechanical variance during drop landing. A university student(age: 24.0 yrs, height: 176.2 cm, weight: 679.5 N) who has no musculoskeletal disorder was recruited as the subject. Hardness, specific gravity, tensile strength, elongation, 100% modulus, tear strength, split tear strength, compression set, resilience, vertical GRF, and loading rate were determined for each material. For each dependent variable, a descriptive statistics was used for different conditions. The property test results showed that tensile strength, tear strength, split tear strength, compression set, and resilience in carbon nanotube-based shock absorbers were greater than general Ethylene Vinyl Acetate(EVA). These indicated that resistance against variable strength in developed carbon nanotube-based shock absorbers were greater than general EVA. In vertical GRF of CNTC was less than those of EVA during drop landing and loading rate of CNTC was greater than EVA. It seems that the use of CNT can be a effective way of reducing and controlling shock from impact.