• Journal of Advanced Marine Engineering and Technology
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• 제26권1호
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• pp.59-67
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• 2002

The comparison of $J_{Rice}$-resistance considering a few strength ratio in Rice J-integral formula and $J_{\delta}$-resistance curves converted from experimental CTOD using appropriate strength chosen according to strain hardening level, n=10.6 (A533B steel) and n=8.1 (BS4360 steel) is carried out. The optimal dimensionless strength ratio like the factor of revision, (see full text)reflecting strain hardening level in Rice\`s experimental formula is found out and the reliability of appropriate reference strength chosen according to strain hardening level in different materials is investigated through doing that CTOD is transformed from $J_{\delta}$-integral using relationship between J-integral and CTOD. The results are as follows; 1) The optimal factor of revision is when m equals to 3 in (see full text) for Rice's and the above optimal factor of revision multiplies by coefficient, η in Rice's experimental formula instead of n=2, 2) and the pertinent reference strength for high strain hardening material like BS4360 steel is ultimate strength, $\sigma_{u}$ and for material like A533B steel is ultimate-flow strength, $\sigma_{u-f}$. The incompatible of the behavior of both experimental J-resistance curves using Rice's formula and CTOD-resistance curves for A533B and BS4360 steel by Gordon, et al., could be corrected using the optimal factor of revision in Rice\`s and the pertinent reference strength in J=$m_{j}$${\times}$$\sigma_{i}$${\times}$CTOD.

• 한국생활과학회지
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• 제9권4호
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• pp.483-489
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• 2000

The purpose of this study is to verify the effect of cellulase treatment on crease resistance of cotton. Cotton fabrics was treated with cellulase under different concentration at $50^{\circ}C$ for 40 min. Also to compare the effect of DMDHEU treatment, DMDHEU treatment was conducted before and after cellulase treatment, also with cellulase. Weight loss, crease resistance and tentile strength of each samples were measured and compared. Maximum weight loss showed at 1g/l con. with 40 min. treatment. Cellulase enzyme treatment was more effective than DMDHEU in the crease resistance and tensile strength. Crease resistant of cotton which treated under different condition with cellulase and DMDHEU showed in the order of cellulase+DMDHEU> cellulase> DMDHEU treatment. Also, tensile strength showed in the order of cellulase> cellulase+DMDHEU> DMDHEU. Among those treatment conditions, condition which treated with cellulase considered more effective to increase crease resistance while keeping tensile strength too.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1267-1272
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• 2000

When fresh concrete is exposed to low temperature, the concrete may suffer frost damage due to freezing at early ages and strength development may be delayed. These are problems on cold weather concrete. One of the solution methods for resolving these problems has been to reduce the freezing temperature of concrete by the use of chemical admixtures called Accelerators for freezing resistance. Therefore, in this study, we executed freezing temperature of mortar, setting and strength properties with using water reducing accelerator and accelerators for freezing resistance which are producted internationally. As a result of this experiment, the freezing temperature of mortar is lower and the setting property is promoted when the admixing content of accelerators for freezing resistance is increased. Moreover, the compressive strength of mortar used accelerators for freezing resistance represented the result which is similar with result of analysis of compressive strength increase with using logistic curve formula, but in the case of plain and using water reducing accelerator, there is no relation between logistic curve formula, maturity and compressive strength.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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• pp.441-446
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• 1994

In this study proposed to rapid and simple test method for early decision of quality of concrete. As the this paper is experimental study for compressive strength of mortar using resistance method, the obtained results are summarized as follow ; $\circled1$ The resistance ratio was decreased as the incement of water-cement ratio $\circled2$ The compressive strength presented to the tendency of increment as resistance ratio is increaing

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.187-191
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• 2008

It is necessary to develop a technology for effectively controling explosive spalling of high strength concrete caused increasing construction of high rise building and putting up the fireproof standard of high strength concrete by MLTM (Ministry of Land, Transport and Maritime Affairs). Accordingly, it was investigated basic properties such as slump, air content and compressive strength, and fire resistance properties of high strength concrete using polypropylene fiber for field application as a countermeasure for explosive spalling of concrete on fire in this study, As a test result, it was confirmed that PP fiber is available as fire resistance method of high strength concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 춘계 학술논문 발표대회
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• pp.21-25
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• 2008

It is the aim of this study to investigate the fire resistance design Guidelines for high-strength concrete structure for example compressive strength more than 40Mpa. It is well know that explosive spalling due to fire attack of high strength concrete is related to concrete failure. so, the purpose of this study introduce the fire A Studty on the Fire Resistance Design Guidelines for High-Strength Concrete Structures of AIK for the response of explosive spalling of high strength concrete.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.67-74
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• 2002

An experimental assessment on the dynamic behavior of saturated sand which can consider the irregular characteristics of earthquakes was proposed. The equivalent uniform stress concept presented by Seed and Idriss has been applied to evaluate the liquefaction resistance strength to simplify earthquake loading. However, it was known that the liquefaction resistance strength of soil based on the equivalent uniform stress concept can't exactly mirror the dynamic characteristics of the irregular earthquake motion. In this study, estimation of the criterion of the liquefaction resistance strength was determined by applying real earthquake loading to the cyclic triaxial test. From the test results, relationships between excess pore water pressure and the earthquake characteristics such as magnitude or duration were determined. Magnitude scaling factors to determine the soil liquefaction resistance strength in seismic design were also proposed.

• Steel and Composite Structures
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• 제23권5호
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• pp.611-621
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• 2017

This paper presents an investigation on the fire resistance of high strength fiber reinforced concrete filled box columns (CFBCs) under combined temperature and loading. Two groups of full-size specimens were fabricated. The control group was a steel box filled with high-strength concrete (HSC), while the experimental group consisted of a steel box filled with high strength fiber concrete (HFC) and two steel boxes filled with fiber reinforced concrete. Prior to fire test, a constant compressive load (i.e., load level for fire design) was applied to the column specimens. Thermal load was then applied on the column specimens in form of ISO 834 standard fire curve in a large-scale laboratory furnace until the set experiment termination condition was reached. The test results show that filling fiber concrete can improve the fire resistance of CFBC. Moreover, the configuration of longitudinal reinforcements and transverse stirrups can significantly improve the fire resistance of CFBCs.

• 한국건축시공학회지
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• 제2권2호
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• pp.151-156
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• 2002

When fresh concrete is exposed to low temperature, the concrete may suffer frost damage due to freezing at early ages and strength development may be delayed. One of the solution methods for resolve these problems is to reduce freezing temperature of concrete by the use of chemical admixture called Accelerators for freezing resistance. In this study, we investigate the effect on strength development of cement mortar using accelerators for freezing resistance with the variance curing condition. As the result of this study, the mortar using accelerators for freezing resistance show that continuously strength development in curing condition of -5$^{\circ}C$. And compressive strength under the variance temperature condition was higher than constant temperature condition in same maturity.

• International Journal of Concrete Structures and Materials
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• 제3권2호
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• pp.97-101
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• 2009

It has been known that acid-resistant concretes on the liquid glass basis have high porosity (up to 18${\sim}$20%), low strength and insufficient water resistance. Therefore they can not be used as materials for load-bearing structural elements. Significant increasing of silicate matrix strength and density was carried out by incorporation of special liquid organic alkali-soluble silicate additives, which block of superficial pores and reduces concrete shrinkage deformation. It was demonstrated that introduction of tetrafurfuryloxisilane additive sharply increases strength, durability and shock resistance of silicate polymer concrete in aggressive media. This effect is attributable to hardening of contacts between silicate binder gel globes and modification of alkaline component owing to "inoculation" of the furan radical. The optimal concrete composition with the increased strength, chemical resistance in the aggressive environments, density and crack resistance was obtained.