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Suil Pyun - One of the best experts on this subject based on the ideXlab platform.
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comparison of susceptibility to pitting corrosion of aa2024 t4 aa7075 t651 and aa7475 t761 aluminium alloys in neutral chloride solutions using electrochemical noise analysis
Corrosion Science, 2008Co-Authors: Suil PyunAbstract:The susceptibility to pitting corrosion of AA2024-T4, AA7075-T651 and AA7475-T761 aluminium alloys was investigated in aqueous neutral chloride solution for the purpose of comparison using electrochemical noise measurement. The experimentally measured electrochemical noises were analysed based upon the combined stochastic theory and shot-noise theory using the Weibull distribution function. From the occurrence of two linear regions on one Weibull Probability Plot, it was suggested that there existed two stochastic processes of uniform corrosion and pitting corrosion; pitting corrosion was distinguished from uniform corrosion in terms of the frequency of events in the stochastic analysis. Accordingly, the present analysis method allowed us to investigate pitting corrosion independently. The susceptibility to pitting corrosion was appropriately evaluated by determining pit embryo formation rate in the stochastic analysis. The susceptibility was decreased in the following order: AA2024-T4 (the naturally aged condition), AA7475-T761 (the overaged condition) and AA7075-T651 (the near-peak-aged condition).
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effects of sulphate nitrate and phosphate on pit initiation of pure aluminium in hcl based solution
Corrosion Science, 2007Co-Authors: Kyunghwan Na, Suil PyunAbstract:Effects of sulphate, nitrate and phosphate ion additives on the pit initiation of pure aluminium were investigated in a hydrochloric acid solution as a function of anion concentration by using potentiodynamic polarisation experiment and electrochemical noise measurement. From the quantitative analysis of the electrochemical noise by using the Weibull distribution function based upon a stochastic theory, it was found that the pit embryo formation rate was increased by the addition of phosphate ions. On the other hand, the pit embryo formation rate was increased up to the sulphate or nitrate ion concentration around 0.05 M and then decreased gradually with increasing sulphate or nitrate ion concentration. Moreover, from the three linear regions in one Weibull Probability Plot in anion-free hydrochloric acid solution, it was concluded that pit initiation was clearly distinguished from uniform corrosion and the stochastic process concerning the series of nucleation, growth and detachment of hydrogen bubbles in the stochastic analysis.
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effect of sulphate and molybdate ions on pitting corrosion of aluminium by using electrochemical noise analysis
Journal of Electroanalytical Chemistry, 2006Co-Authors: Kyunghwan Na, Suil PyunAbstract:The effects of sulphate and molybdate ion additives on the pitting corrosion of pure aluminium were investigated as a function of anion concentration by using potentiodynamic polarisation experiment and electrochemical noise measurement. The cumulative Probability determined from shot-noise theory was quantitatively analysed by using the Weibull distribution function based upon a stochastic theory. From the statistical variation in the frequency of events, it was found that the width of the distribution of the frequency of events was broader in the presence of sulphate ions. On the other hand, the distribution of the frequency of events shifted to a lower frequency region in the presence of molybdate ions. From the results, it was concluded that both sulphate and molybdate ions retards the pit initiation. Moreover, from the two linear regions in one Weibull Probability Plot, it was concluded that pitting corrosion was clearly distinguished from uniform corrosion in the stochastic analysis.
Tomohiro Hirose - One of the best experts on this subject based on the ideXlab platform.
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pos0651 clinical and functional response to tofacitinib in patients with rheumatoid arthritis Probability Plot analysis of results from a 48 week phase 3b 4 methotrexate withdrawal study
Annals of the Rheumatic Diseases, 2021Co-Authors: Stanley Cohen, Haiyun Fan, Tomohiro Hirose, Y H Chen, N Sugiyama, Jose Luis Rivas, Annette Diehl, Tatjana Lukic, J Paulissen, Edward C KeystoneAbstract:Background: The Phase 3b/4 study ORAL Shift (NCT02831855) demonstrated sustained efficacy/safety of tofacitinib modified-release 11 mg QD following MTX withdrawal, that was non-inferior to continued tofacitinib + MTX use, in patients (pts) with moderate to severe RA who achieved LDA with tofacitinib + MTX at Week (W)24.1 Objectives: To assess differences and similarities in clinical/functional responses in pts receiving tofacitinib ± MTX in ORAL Shift. Methods: In ORAL Shift, pts received open-label tofacitinib + MTX to W24; at W24, pts who achieved CDAI LDA were randomised to receive tofacitinib + MTX or tofacitinib + placebo (PBO) from W24–48. In this post hoc analysis, clinical efficacy endpoints were ACR-N (minimum % change from baseline [BL; Δ] at W48 achieved by each pt in 3 efficacy measures), ΔDAS28-4(ESR), and DAS28-4(ESR) remission/LDA (scores ≤3.2) and moderate/high disease activity (scores >3.2). Functional efficacy endpoints were ΔHAQ-DI and HAQ-DI clinically relevant functional progression (CRFP) status at W48, defined as failure to achieve improvement in HAQ-DI ≥ minimum clinically important difference (MCID; ≥0.22 decrease from BL in HAQ-DI). Thus, CRFP was defined as W24–48 were assessed by response subgroups. Results: 266 pts receiving tofacitinib + MTX and 264 pts receiving tofacitinib + PBO in W24–48 were included. At W48: mean ACR-N was numerically greater with tofacitinib + MTX vs tofacitinib + PBO (60.8 vs 53.1); mean decrease in HAQ-DI was generally similar between groups (-0.71 vs -0.67); mean decrease in DAS28-4(ESR) was numerically greater with tofacitinib + MTX vs tofacitinib + PBO (-2.95 vs -2.68). The differences/similarities between groups in ACR-N and ΔHAQ-DI were also seen in cumulative Probability Plots (Figure 1). CRFP rates were numerically lower with tofacitinib + MTX (18.7%) vs tofacitinib + PBO (23.5%), and in pts with remission/LDA (tofacitinib + MTX, 12.1%; tofacitinib + PBO, 16.8%) vs moderate/high disease activity (tofacitinib + MTX, 26.2%; tofacitinib + PBO, 30.8%). Median of mean CRP over time was generally numerically lower in pts with CRFP vs non-CRFP and DAS28-4(ESR)-defined remission/LDA vs moderate/high disease activity; and in those receiving tofacitinib + PBO vs tofacitinib + MTX, irrespective of CRFP or DAS28-4(ESR) disease status (Table 1). Conclusion: Although clinical/functional responses were generally similar between treatment groups, numerical improvements were seen for some efficacy endpoints with tofacitinib + MTX vs tofacitinib + PBO. A numerically higher CRFP rate may be associated with higher DAS28-4(ESR) disease activity. CRP changes up to W48 may not trend with CRFP status. References: [1]Cohen et al. Lancet Rheumatol 2019; 1: E23-34. Acknowledgements: Study sponsored by Pfizer Inc. Medical writing support was provided by Anthony G McCluskey, CMC Connect, and funded by Pfizer Inc. Disclosure of Interests: Stanley B. Cohen Consultant of: AbbVie, Eli Lilly, Genentech, Gilead Sciences, Pfizer Inc, Grant/research support from: AbbVie, Eli Lilly, Genentech, Gilead Sciences, Pfizer Inc, Yi-Hsing Chen Grant/research support from: Bristol-Myers Squibb, GlaxoSmithKline, Pfizer Inc, Naonobu Sugiyama Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Jose Luis Rivas Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Annette Diehl Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Tatjana Lukic Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Jerome Paulissen Consultant of: Pfizer Inc, Haiyun Fan Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Tomohiro Hirose Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Edward Keystone Speakers bureau: AbbVie, Amgen, F. Hoffman-La Roche, Janssen, Merck, Novartis, Pfizer Inc, Sanofi Genzyme, Consultant of: AbbVie, Amgen, Bristol-Myers Squibb, Celltrion, Eli Lilly, F. Hoffman-La Roche, Gilead Sciences, Janssen, Merck, Myriad Autoimmune, Pfizer Inc, Sandoz, Sanofi Genzyme, Samsung Bioepsis, Grant/research support from: Amgen, Merck, Pfizer Inc, PuraPharm
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sat0252 clinical and functional response to tofacitinib and adalimumab in patients with rheumatoid arthritis Probability Plot analysis of results from the oral strategy trial
Annals of the Rheumatic Diseases, 2018Co-Authors: T Takeuchi, Josef S Smolen, Roy Fleischmann, Noriko Iikuni, Haiyun Fan, Koshika Soma, Ermeg Akylbekova, Tomohiro HiroseAbstract:Background: Tofacitinib is an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis (RA). ORAL Strategy (NCT02187055), a 12-month, global, Phase 3b/4 study, demonstrated that in patients with RA and an inadequate response to methotrexate (MTX), tofacitinib + MTX was non-inferior to adalimumab + MTX, while tofacitinib monotherapy was not non-inferior to either combination based on American College of Rheumatology (ACR)50 response rates at Month 6. 1 Objectives: To assess clinical and functional efficacy across treatments in the ORAL Strategy trial using cumulative Probability Plots. Methods: Efficacy was evaluated between patients who received tofacitinib 5 mg twice daily (BID) as monotherapy (N=384), tofacitinib 5 mg BID + MTX (N=376) and adalimumab 40 mg subcutaneously once every 2 weeks + MTX (N=386) based on ACR responses and changes from baseline in Health Assessment Questionnaire-Disability Index (ΔHAQ-DI) score at Month 12. Cumulative Probability Plots for ACR-n (where ACR is the % improvement from baseline in ACR components, and n represents the mimimum % achieved by each patient) and ΔHAQ-DI are presented. The area under the curve (AUC) was calculated for ACR-n up to Month 12 (in months), and an analysis of covariance model was used to assess treatment effects in terms of the AUC of ACR-n at Month 12; there was no adjustment for multiplicity for this post hoc analysis. Results: The cumulative Probability Plots of ACR responses at Month 12 indicated that the proportion of patients who achieved responses of ACR20, ACR50 and ACR70 was similar for tofacitinib + MTX and adalimumab + MTX, but was numerically smaller for tofacitinib monotherapy (figure, A). Responses of approximately ≥ACR80 were achieved by a similar proportion of patients in each treatment group. Least squares mean (standard error) AUC of ACR-n up to Month 12 (in months) was similar for tofacitinib + MTX (437 [35]) and adalimumab + MTX (402 [35]), but was smaller for tofacitinib monotherapy (319 [35]; p Figure 1 Cumulative Probability Plot of A) ACR response and B) VHAQ-DI at Month 12 Two outlets for ACR response are not shown: tofacitinib 5 mg BID monotherapy, ACR-n-1700, cumulative Probability-0.0003; adailmumab 40 mg SC Q2W + MTX, ACR-n-463, cumulative Probability-0.003 Conclusions: These data support the primary ORAL Strategy findings, 1 indicating that in patients with RA, clinical efficacy, based on ACR response, was generally similar for tofacitinib + MTX and adalimumab + MTX, while a smaller proportion of patients who received tofacitinib monotherapy achieved ACR response in general, and particularly for Reference [1]Fleischmann R, et al. Lancet2017;390:457–68. Acknowledgements: Study sponsored by Pfizer Inc. Medical writing support was provided by A MacLachlan of CMC and funded by Pfizer Inc. Disclosure of Interest: T. Takeuchi Grant/research support from: AbbVie, Asahi Kasei, Astellas, AstraZeneca, AYUMI, Bristol-Myers Squibb, Chugai, Daiichi Sankyo, Eisai, Eli Lilly Japan, Janssen, Mitsubishi Tanabe, Nippon Kayaku, Novartis, Pfizer Japan Inc, Taiho, Taisho Toyama, Takeda, Teijin, Consultant for: AbbVie, Asahi Kasei, Astellas, AstraZeneca, AYUMI, Bristol-Myers Squibb, Chugai, Daiichi Sankyo, Eisai, Eli Lilly Japan, Janssen, Mitsubishi Tanabe, Nippon Kayaku, Novartis, Pfizer Japan Inc, Taiho, Taisho Toyama, Takeda, Teijin, Speakers bureau: AbbVie, Asahi Kasei, Astellas, AstraZeneca, AYUMI, Bristol-Myers Squibb, Chugai, Daiichi Sankyo, Eisai, Eli Lilly Japan, Janssen, Mitsubishi Tanabe, Nippon Kayaku, Novartis, Pfizer Japan Inc, Taiho, Taisho Toyama, Takeda, Teijin, J. Smolen Grant/research support from: AbbVie, Eli Lilly, Janssen, MSD, Pfizer Inc, Roche, Consultant for: AbbVie, Amgen, AstraZeneca, Astro, Celgene, Celtrion, Eli Lilly, GSK, ILTOO, Janssen, MedImmune, MSD, Novartis-Sandoz, Pfizer Inc, Roche, Samsung, Sanofi, UCB, Speakers bureau: AbbVie, Amgen, AstraZeneca, Astro, Celgene, Celtrion, Eli Lilly, GSK, ILTOO, Janssen, MedImmune, MSD, Novartis-Sandoz, Pfizer Inc, Roche, Samsung, Sanofi, UCB, R. Fleischmann Consultant for: AbbVie, Amgen, AstraZeneca, Bristol-Myers Squibb, Celltrion, Eli Lilly, Genentech, GSK, Janssen, Novartis, Pfizer Inc, Sanofi-Aventis, UCB, N. Iikuni Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, H. Fan Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, K. Soma Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, E. Akylbekova Consultant for: Pfizer Inc, Employee of: IQVIA, T. Hirose Shareholder of: Pfizer Japan Inc, Employee of: Pfizer Japan Inc
Kyunghwan Na - One of the best experts on this subject based on the ideXlab platform.
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effects of sulphate nitrate and phosphate on pit initiation of pure aluminium in hcl based solution
Corrosion Science, 2007Co-Authors: Kyunghwan Na, Suil PyunAbstract:Effects of sulphate, nitrate and phosphate ion additives on the pit initiation of pure aluminium were investigated in a hydrochloric acid solution as a function of anion concentration by using potentiodynamic polarisation experiment and electrochemical noise measurement. From the quantitative analysis of the electrochemical noise by using the Weibull distribution function based upon a stochastic theory, it was found that the pit embryo formation rate was increased by the addition of phosphate ions. On the other hand, the pit embryo formation rate was increased up to the sulphate or nitrate ion concentration around 0.05 M and then decreased gradually with increasing sulphate or nitrate ion concentration. Moreover, from the three linear regions in one Weibull Probability Plot in anion-free hydrochloric acid solution, it was concluded that pit initiation was clearly distinguished from uniform corrosion and the stochastic process concerning the series of nucleation, growth and detachment of hydrogen bubbles in the stochastic analysis.
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effect of sulphate and molybdate ions on pitting corrosion of aluminium by using electrochemical noise analysis
Journal of Electroanalytical Chemistry, 2006Co-Authors: Kyunghwan Na, Suil PyunAbstract:The effects of sulphate and molybdate ion additives on the pitting corrosion of pure aluminium were investigated as a function of anion concentration by using potentiodynamic polarisation experiment and electrochemical noise measurement. The cumulative Probability determined from shot-noise theory was quantitatively analysed by using the Weibull distribution function based upon a stochastic theory. From the statistical variation in the frequency of events, it was found that the width of the distribution of the frequency of events was broader in the presence of sulphate ions. On the other hand, the distribution of the frequency of events shifted to a lower frequency region in the presence of molybdate ions. From the results, it was concluded that both sulphate and molybdate ions retards the pit initiation. Moreover, from the two linear regions in one Weibull Probability Plot, it was concluded that pitting corrosion was clearly distinguished from uniform corrosion in the stochastic analysis.
Junhaeng Heo - One of the best experts on this subject based on the ideXlab platform.
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comparison on Probability Plot correlation coefficient test considering skewness of sample for the gev distribution
Journal of Korea Water Resources Association, 2014Co-Authors: Hongjoo Shi, Sooyoung Kim, Junhaeng HeoAbstract:It is important to estimate an appropriate quantile for design of hydraulic structure. For this purpose, it is necessary to find the appropriate Probability distribution which can represent the sample data well. Probability Plot correlation coefficient test as one of goodness-of-fit test, is recently developed and has been known as a simple and powerful method. In this study, Probability Plot correlation coefficient test statistics using the Plotting position considering the coefficients of skewness for the GEV distribution is derived, and represented by the regression equation. Monte-Carlo method is also performed to compare the rejection power between each method. As the results, the Probability Plot correlation coefficient test which is derived in this study is better than the others. In particular, when sample size is small and distribution has the shape parameter, rejection power of Probability Plot correlation coefficient test considering the coefficients of skewness is bigger than the others.
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comparison of the Probability Plot correlation coefficient test statistics for the general extreme value distribution
World Environmental and Water Resources Congress 2010: Challenges of Change, 2010Co-Authors: Sooyoung Kim, Junhaeng HeoAbstract:A proper Probability distribution for estimating a quantile is selected by the goodness of fit tests in frequency analysis. The Probability Plot correlation coefficient(PPCC) test has been known as powerful and easy test among the goodness of fit tests. Generally, the PPCC test statistics are affected by significance levels, sample sizes, Plotting position formulas, and shape parameters in case that a given distribution includes a shape parameter. Therefore, it is important to select an exact Plotting position formula for the PPCC test statistics for a given Probability distribution. After Cunnane(1978) defined the Plotting position that related with the mean of data, many researches have accomplished about the Plotting position formulas considered the influence of coefficients of skewness related with shape parameters. In this study, the PPCC test statistics are derived by using a Plotting position formula developed from theoretical reduced variates with a term of a coefficient of skewness for the general extreme value(GEV) distribution. In addition, the PPCC test statistics are estimated by considering various sample sizes, significance levels, and shape parameters of the GEV distribution. The performance of derived PPCC test statistics is evaluated by estimating the rejection rate of population from Monte Carlo simulation.
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regression equations of Probability Plot correlation coefficient test statistics from several Probability distributions
Journal of Hydrology, 2008Co-Authors: Junhaeng Heo, Hongjoo Shi, Sooyoung Kim, Youn Woo Kho, Taesoo KimAbstract:Summary The Probability Plot correlation coefficient (PPCC) test has been known as a powerful but easy-to-use goodness-of-fit test. However, the application of PPCC test statistics is sometimes difficult since the test statistics are generally derived in tabulated form and the number of test statistics is significant. In this study, the PPCC test statistics for the normal, Gumbel, gamma, GEV, and Weibull distributions are derived, and regression equations of the PPCC test statistics for those models are formulated as a function of the significance levels, sample sizes, and skewness coefficients depending on the models. Monte Carlo simulation for power tests were performed to compare the rejection capability of the PPCC test with those of the χ 2 , Cramer von Mises, and Kolmogorov–Smirnov tests for several Probability distributions. The power test results indicated that the PPCC and χ 2 -tests had better rejection performances than the CVM and K–S tests did when the parent and applied models were identical. Moreover, the PPCC test showed the most powerful rejection rate, followed by the χ 2 -test, while the CVM was the worst when the parent and applied models were different. In addition, the power of rejection increased with sample size when the parent and applied models were different. However, the rejection power did not vary appreciably with sample size when the parent and applied models were identical.
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derivation of the Probability Plot correlation coefficient test statistics for the generalized logistic and the generalized pareto distributions
World Environmental and Water Resources Congress 2008: Ahupua'A, 2008Co-Authors: Sooyoung Kim, Youn Woo Kho, Hongjoon Shin, Junhaeng HeoAbstract:The selection of appropriate Probability distribution is important in frequency analysis to estimate the accurate quantile. Generally, the selection of appropriate Probability model is based on the goodness of fit test. The Probability Plot correlation coefficient (PPCC) test has been known as powerful and easy test among the goodness of fit tests. In this study, the derivation of the PPCC test statistics for the generalized logistic distribution and the generalized Pareto distribution was performed by considering sample sizes, significance levels, and shape parameters. In addition, the correlation coefficients between orderly generated data sets and fitted quantiles were computed by using various Plotting position formulas. Monte Carlo simulation was performed to select an appropriate Plotting position formula for assumed Probability distributions. As the results, the Gringorten’s Plotting position formula was selected for given distributions. Finally, the PPCC test statistics for given Probability distributions were derived from correlation coefficient values based on the selected Plotting position formula considering various shape parameters.
Shinji Yokogawa - One of the best experts on this subject based on the ideXlab platform.
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two step Probability Plot for parameter estimation of lifetime distribution affected by defect clustering in time dependent dielectric breakdown
Japanese Journal of Applied Physics, 2017Co-Authors: Shinji YokogawaAbstract:In this study, a simple method of statistical parameter estimation is proposed for lifetime distribution that has three parameters due to the defect clustering in the middle-of-line and back-end-of-line. A two-step procedure provides the estimations of distribution parameters effectively for the time-dependent dielectric breakdown. In the first step, a clustering parameter of distribution, which is one of the shape parameters, is estimated by a linearization treatment of Plotted data on the proposed chart. Then, in the second step, shape and scale parameters are estimated by calculating of a slope and an intercept, respectively. The statistical accuracy of the estimates is evaluated using the Monte-Carlo simulation technique and mean squared error of estimates.
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impacts of censoring on lifetime analysis by two step Probability Plot in defect clustered tddb
International Reliability Physics Symposium, 2017Co-Authors: Shinji YokogawaAbstract:Lifetime distribution characteristics of FEOL/MOL/ BEOL time-dependent breakdown (TDDB) with defect clustering conditions were investigated by using a recently proposed two-step Probability Plot. This method was proposed to estimate parameters of the lifetime distribution function that is based on the defect clustering concept, and has two shape parameters. In the first step, the clustering parameter is estimated by a linearization procedure on a proposed chart. In the second step, shape and scale parameters are estimated by the slope and intercept of the Plot. The impacts of censoring are investigated statistically by using Monte Carlo simulation (MCS) and the mean squared error (MSE) of the estimators.
