• Journal of the Korean Data and Information Science Society
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• 제21권5호
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• pp.935-944
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• 2010

In this paper, we develop the noninformative priors for the reliability in a stress-strength model where a strength X and a stress Y have independent exponential distributions with different scale parameters and a common location parameter. We derive the reference priors and prove the propriety of joint posterior distribution under the general prior including the reference priors. Through the simulation study, we show that the proposed reference priors match the target coverage probabilities in a frequentist sense.

• 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.

• Structural Engineering and Mechanics
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• 제82권1호
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• pp.93-105
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• 2022

The brittleness of concrete can be overcome by fiber reinforcement that controls the crack mechanisms of concrete. Corrosion-related durability issues can be prevented by synthetic fibers (SFs), while macro synthetic fibers have proven to be particularly effective to provide ductility and toughness after cracks. This experimental study has been performed to investigate the comparative flexural and mechanical behavior of four different macro-synthetic fiber-reinforced concretes (SFRCs). Two polyamide fibers (SF1 and SF2) with different aspect ratios and two different polypropylene fiber types (SF3 and SF4) were used in production of SFRCs. Four different SFRCs and reference concrete were compared for their influences on the toughness, compressive strength, elastic modulus, flexural strength, residual strength and splitting tensile strength. The outcomes of the study reveal that the flowability of reference mixture decreases after addition of SFs and the air voids of all SFRC mixtures increased with the addition of macro-synthetic fibers except SFRC2 mixture whose air content is the same as the reference mixture. The results also revealed that with the inclusion of SFs, 11.34% reduction in the cube compressive strength was noted for SFRC4 based on that of reference specimens and both reference concrete and SFRC exhibited nearly similar cylindrical compressive strength. Results illustrated that SFRC1 and SFRC4 mixtures consistently provide the highest and lowest flexural toughness values of 36.4 joule and 27.7 joule respectively. The toughness values of SFRC3 and SFRC4 are very near to each other.

• Journal of the Korean Data and Information Science Society
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• 제22권1호
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• pp.115-123
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• 2011

In this paper, we develop the noninformative priors for stress-strength reliability from the Pareto distributions. We develop the matching priors and the reference priors. It turns out that the second order matching prior does not match the alternative coverage probabilities, and is not a highest posterior density matching or a cumelative distribution function matching priors. Also we reveal that the one-at-a-time reference prior and Jeffreys' prior are the second order matching prior. We show that the proposed reference prior matches the target coverage probabilities in a frequentist sense through simulation study, and an example is given.

• Communications for Statistical Applications and Methods
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• 제18권4호
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• pp.467-475
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• 2011

This paper develops the noninformative priors for the stress-strength reliability from one parameter generalized exponential distributions. When this reliability is a parameter of interest, we develop the first, second order matching priors, reference priors in its order of importance in parameters and Jeffreys' prior. We reveal that these probability matching priors are not the alternative coverage probability matching prior or a highest posterior density matching prior, a cumulative distribution function matching prior. In addition, we reveal that the one-at-a-time reference prior and Jeffreys' prior are actually a second order matching prior. We show that the proposed reference prior matches the target coverage probabilities in a frequentist sense through a simulation study and a provided example.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.416-421
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• 2004

Off-line feedrate scheduling is presented as the advanced technology to regulate cutting forces at the desired level through change of feedrates. In rough cutting, the feedrate scheduling aims at reducing the machining time, which is the most important factor for better productivity. Thus, the largest force which can avoid breakage of tool shank and tooth is a reference force for feedrate scheduling in rough cutting. In this paper, a calculation method of the reference cutting force for feedrate scheduling is developed. This model calculates rupture plane of tooth using the FEM analysis of a tool and computes the reference force using the transverse rupture strength of a tool. Experiments validate that the presented feedrate scheduling model reduced machining time drastically and regulate cutting forces at the reference cutting force.

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2005년도 추계학술대회
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• pp.27-34
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• 2005

We consider the problem of estimating the system reliability noninformative priors when both stress and strength follow generalized gamma distributions. We first derive Jeffreys' prior, group ordering reference priors, and matching priors. We investigate the propriety of posterior distributions and provide marginal posterior distributions under those noninformative priors. We also examine whether the reference priors satisfy the probability matching criterion.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.65-68
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• 2006

In this study, comparison of setting time, compressive strength, watertightness and durability of between reference mortar with mortar using waterproof admixtures based on natural inorganic minerals. Test results shows that waterproof admixtures does not change setting time of mortar, but strongly improve compressive strength, permeability, absorption and durability of mortar. Especially early strength of mortar increased about 40% of reference.

• Steel and Composite Structures
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• 제46권5호
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• pp.689-707
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• 2023

Geopolymer concrete production is interesting as it is an alternative to portland cement concrete. However, workability, setting time and strength expectations limit the sustainable application of geopolymer concrete in practice. This study aims to improve the production of geopolymer concrete to mitigate these drawbacks. The improvement in the workability and setting time were achieved with the additional use of NaOH solution whereas an increase in the strength was gained with the addition of recycled steel fibers from waste tires. In addition, the use of 25% basalt powder instead of fly ash and the addition of recycled steel fibers from waste tires improved its environmental feature. The samples with steel fiber ratios ranging between 0.5% and 5% and basalt powder of 25%, 50% and 75% were tested under both compressive and flexure forces. The compressive and flexural capacities were significantly enhanced by utilizing recycled steel fibers from waste tires. However, decreases in these capacities were detected as the basalt powder ratio increased. In general, as the waste wire ratio increased, the compressive strength gradually increased. While the compressive strength of the reference sample was 26 MPa, when the wire ratio was 5%, the compressive strength increased up to 53 MPa. With the addition of 75% basalt powder, the compressive strength decreases by 60%, but when the 3% wire ratio is reached, the compressive strength is obtained as in the reference sample. In the sample group to which 25% basalt powder was added, the flexural strength increased by 97% when the waste wire addition rate was 5%. In addition, while the energy absorption capacity was 0.66 kN in the reference sample, it increased to 12.33 kN with the addition of 5% wire. The production phase revealed that basalt powder and waste steel wire had a significant impact on the workability and setting time. Furthermore, SEM analyses were performed.

• 한국멀티미디어학회논문지
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• 제21권7호
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• pp.772-778
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• 2018

We have previously proposed a preliminary cut-off indoor positioning scheme considering the reference point with the same signal similarity. This scheme estimates the position using the relative rank of the peak of received signal strength from the beacons around user. However, this scheme has a weak point with lower accuracy when there are more than one nearest reference points having the same signal similarity. In order to tackle this, we propose a weighted preliminary cut-off indoor positioning scheme. Firstly, if the above problem occurs, the similarity to the peak of signal strength is considered as well as the relative rank. Next, weights are assigned to the nearest reference points using the similarity to the peak of the received signal strength. Finally, the user's position is estimated by applying the weights. As a result, the weighted preliminary cut-off scheme improves the positioning accuracy by about 7.9% compared to the previous scheme.