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황정택(Jeong Taek Hwang),목진용(Jin Yong Mok),이승일(Seung Il Lee),이희성(Hi Sung Lee) 한국철도학회 2006 한국철도학회 학술발표대회논문집 Vol.- No.-
Derailment is likely to have a direct connection with human life and must be eliminated. A traveling safety evaluation method based mainly on derailment coefficient has already established. But this method is very difficult because Derailment is caused by multiple factors. To evaluate the derailment factor of running train that runs on the curved track, we make use of mechanism that wheel loads and lateral forces were affected by track and rolling stock parameter. In this paper, deal with a search on the parameter and derailment factor. According to results of computer simulation value of Q/P, running safety is connected with operation velocity, curve radius, cant, track irregularity, suspension stiffness and static wheel load ratio, etc.
황정택,김종학,전주연,한재현,Hwang, Jeong Taek,Kim, Jong Hak,Jeon, Ju Yeon,Han, Jae Hyeon 한국안전학회 2017 한국안전학회지 Vol.32 No.5
This paper is to introduce the main modeling assumptions and data structures associated with right-censored data to describe the successful methodological ideas for analyzing such a field-failure-data when components operating in different environments. The Kaplan - Meier method is the most popular method used for survival analysis. Together with the log-rank test, it may provide us with an opportunity to estimate survival probabilities and to compare survival between groups. An important advantage of the Kaplan - Meier curve is that the method can take into account some types of censored data, particularly right-censoring. The above non-parametric method was used to verify the equality of parts life used in different environments. After that, we performed the life distribution analysis using the parametric method. We simulated data from three distributions: exponential, normal, and Weibull. This allowed us to compare the results of the estimates to the known true values and to quantify the reliability indices. Here we used the Akaike information criterion to find a suitable life time distribution. If the Akaike information criterion is the smallest, the best model of failure data is presented. In this paper, no-nparametrics and parametrics methods are analyzed using R program which is a popular statistical program.
골아세포주 MC3T3 - E1 에서 제 1형 Collagen mRNA 발현에 대한 Fluoride의 영향
김진우,최영길,김영설,김광원,양인명,우정택,김성운,서광식,정규림,황정빈 대한내분비학회 1993 Endocrinology and metabolism Vol.8 No.3
Fluoride is one of the most potent stimulators of bone formation in vivo. But its direct effects on osteoblast is not yet clear. This study was to investigate the effects of sodium fluoride on alkaline phosphatase (ALP) activity and type I α2 collagen ribonucleic acid (mRNA) level in osteoblast-like (MC3T3-E1) cells. The cells were cultured in α-minimal esential medium (α-mem) supplemented with 10% fetal bovine serm (FBS) and then changed to 1.1% FBS with various concentration of sodium fluoride. The ALP activity was assayed by the method of Lowry with disodium phenyl phosphate as substrate. Type I α2 collagen ribonucleic acid (mRNA) expression was studied by Nothern blot analysis. Sodium fluoride increased ALP activity at concentration of 2 μM, 4 μM, and 10 μM significantly different form control (p$lt;0.001). ALP activity revealed maximum value at 10uM in this study. Nothern blot analysis of sodium fluoride treated cells, using type 1,2 collagen probe, revealed significant increase at 10 μM in MC3T3-. From this study we could suspect increased collagen synthesis to sodium fluoride from incrteased expression of clollagen gene from osteoblst. Further studies are need to reveal control mechanism of fluoride on collagen gene regulation (J Kor Soc Endocrinol 8: 334~339, 1993).