• The Korean Journal of Applied Statistics
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• v.27 no.3
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• pp.445-459
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• 2014

As a certain job is repeatedly done by a worker, the outcome comparative to the effort to complete the job gets more remarkable. The outcome may be the time required and fraction defective. This phenomenon is referred to a learning-curve effect. We focus on the parametric modeling of the learning-curve effects on count data using a logistic cumulative distribution function and some probability mass functions such as a Poisson and negative binomial. We conduct various simulation scenarios to clarify the characteristics of the proposed model. We also consider a real application to compare the two discrete-type distribution functions.

• Composites Research
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• v.28 no.4
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• pp.182-190
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• 2015

The phenomenological evolution laws of damage can be defined either based on residual life or residual strength. The failure of a specimen can be defined immediately after or before fracture. The former is called in this paper by "failure defined by approach I" and the latter "failure defined by approach II." Usually at failure there is a discontinuity of loading variables and, because of this, damage at failure is discontinuous. Therefore the values of damage at failure by two different approaches are not the same. Based on this idea the sequence effects of the phenomenological evolution law of damage given by $dD/dN=g(D)f({\Phi})$ were studied. Thin-walled graphite/epoxy tubes consisting of four of $[{\pm}45]_s$ laminates were used for the experimental study of sequence effects and the effects of mean stress on fatigue life. It was found that the sequence effects in two step uniaxial fatigue for $[{\pm}45]_s$ graphite/epoxy tubular specimen showed that a high-low block loading sequence was less damaging than a low-high one.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.5
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• pp.597-602
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• 2001

This study was conducted to examine the relationships between the methods used to determine the number of transferable embryos collected per flush and the estimated cumulative genetic improvements in the Japanese Holstein MOET breeding population. Cumulative genetic improvements were predicted by Monte Carlo simulation using three different determination methods (MODEL 1, MODEL 2, and MODEL 3), for calculating the number of embryos collected per flush. Moreover EBVs were estimated including or ignoring coefficients of inbreeding in MME. Inbreeding coefficients were also predicted. The number of transferable embryos was determined using normal, gamma, and Poisson distributions in MODEL 1, gamma and Poisson distributions in MODEL 2, and only the Poisson distribution in MODEL 3. The fitness of MODEL 2 in relation to field data from Hokkaido Japan was the best, and the results for MODEL3 indicated that this model is unsuitable for determining the number of transferable embryos. The largest cumulative genetic improvement (3.11) in the 10th generation was predicted by MODEL 3 and the smallest (2.83) by MODEL 2. Mean coefficients of correlation between the true and estimated breeding values were 0.738, 0.729, and 0.773 in MODELS 1, 2, and 3, respectively. It is suggested that the smallest genetic improvement in MODEL 2 resulted from the smallest correlation coefficient between the true and estimated breeding values. The differences in milk, fat, and protein yields between MODELS 2 and 3 were 182.0, 7.0, and 5.6 kg, respectively, in real units when each trait was independently selected. The inbreeding coefficient was the highest (0.374) in MODEL 2 and the lowest (0.357) in MODEL 3. The effects of different methods for determining the number of transferable embryos per flush on genetic improvements and inbreeding coefficients of the simulated populations were remarkable. The effects of including coefficients of inbreeding in MME, however, were unclear.

• Journal of Preventive Medicine and Public Health
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• v.28 no.2 s.50
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• pp.386-397
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• 1995

A cross sectional study was performed to evaluate the neurobehavioral effects of chronic exposure of complex organic solvents, using NCTB(Neurobehavioral Core Test Battery) recommended by WHO(World Health Organization). Forty female shoe factory workers and twenty-two controls matched with age were participated. The tests were performed in the morning before start of work, to exclude the effects of acute exposure. Workers were exposed mainly to toluene, methyl ethyl ketone, n-hexane, cyclo-hexane, dichloroethylene, trichloroethylene, benzene, xylenes etc. The ranges of present solvent exposure of hygienic effect were $0.46\sim0.71$ in the process using adhesives indirectly, and $1.83\sim2.39$ in the process using it directly. We reclassified the subjects, according to cumulative exposure. It showed significantly poorer performances in high exposed group on Santa Ana Dexterity and Benton Visual Retention, compared with control group. After controlling confounder, the significances were still remained. But, further cohort studies, having the information of personal exposure dose from entering a factory, are required to clarify the effects of chronic exposure of complex organic solvents in relation to dose and duration of exposure.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.8
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• pp.1110-1117
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• 2001

Responses of the rumen fungus, Neocallimastix frontalis RE1, to long chain fatty acid (LCFA) were evaluated by measuring gas production, filter paper (FP) cellulose digestion and polysaccharidase enzyme activities. LCFA (stearic acid, $C_{18:0}$; oleic acid, $C_{18:1}$; linoleic acid, $C_{18:2}$ and linolenic acid, $C_{18:3}$) were emulsitied by ultrasonication under anaerobic condition, and added to the medium. When N frontalis RE1 was grown in culture with stearic, oleic and linoleic acid, the cumulative gas production, gas pool size, FP cellulose digestion and enzymes activities significantly (p<0.05) increased at some incubation times(especially, exponential phases of fungal growth, 48~120 h of incubation) relative to that for control cultures. However, the addition of linolenic acid strongly inhibited all of the investigated parameters up to 120 h incubation, but not after 168 and 216 h of incubation. These results indicated that stearic, oleic and linoleic acids tended to have great stimulatory effects on fungal cellulolysis, whereas linolenic acid caused a significant (p<0.05) inhibitory effects on the cellulolysis by the rumen fungus. These results are the first report of the effect of LCFAs on the ruminal fungi. Further research is needed to identify the mode of action of LCFAs on fungal strains and to verify whether or not ruminal fungi have ability to hydrate unsaturated LCFAs to saturated FAs. There was high correlation between cumulative in vitro gas production and fungal growth (94.78%), FP cellulose degradation (96.34%), CMCase activity(90.86%) or xylanase activity (87.67%). Thus measuring of cumulative gas production could be a useful tool for evaluating fungal growth and/or enzyme production by ruminal fungi.

• Journal of the Economic Geographical Society of Korea
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• v.17 no.3
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• pp.554-566
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• 2014

This paper analyses the relationship between regional economic power defined as GRDP per capita and various socioeconomic variables such as fiscal variables(revenue, expenditure, etc.) as well as nonfiscal variables(population, ratio of old population, unemployment rate, dependency ration) using the pooling data of 16 local governments from 1998 to 2012. To put it concretely, following the Granger causality test, regression analysis has been done with the regional economic power being the dependent and variables which have either one or two direction causality being independent variables. And test of cumulative effects has been done with variables showing statistical significance in the regression analysis. Local tax revenues per capita, expenditures of social development per capita and median age have positive effects, while dependency ratio has negative effect on regional economy. And national subsidy per capita, local tax revenues per capita, expenditures of social development per capita and median age all have cumulative effects on regional economy.

• Molecular & Cellular Toxicology
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• v.5 no.2
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• pp.165-171
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• 2009

Biomarkers indicating past exposure to radiation have not yet been entirely satisfactory. In this study, we validated several genes reported as radiation response genes, as biomarkers to detect past exposure to radiation in occupationally exposed workers, especially workers in the medical field. A total of 54 radiation workers in hospital were investigated for radiation exposure dose. Their average radiation dose of recent one year was 1.09 mSv ($\pm$1.63) with a 10.63 mSv ($\pm$12.91) cumulative dose. The results of the multiple regression analysis for the various variables indicate that the Hsc70 (P=0.0292) and ORAL (P=0.0045) may be candidate biomarkers for the recent 1 year radiation exposure in radiation workers, whereas AEN (P=0.0334) and PGAMI (P=0.0003) might be for cumulative exposure.

• Childhood Kidney Diseases
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• v.20 no.2
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• pp.45-49
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• 2016

Purpose: This study was performed to evaluate the effects of cyclosporine-A (CsA) on linear growth in pediatric patients with steroid-dependent (SDNS) or resistant nephrotic syndrome (SRNS). Methods: Thirty-five pediatric patients with SDNS or SRNS undergoing glucocorticoid (GC) and/or CsA treatment were retrospectively reviewed. Seventeen patients were treated with GC alone and 18 were treated with GC and CsA. The cumulative doses of GC and CsA were quantified (mg/kg/day). Linear growth during the follow-up period was defined as the difference in Z-score between the initial and final height according to the follow-up period (${\Delta}$ height Z score/year). The associations between linear growth and clinical parameters were analyzed. Results: The linear growth of patients in the two groups was not significantly different (P=0.262). The ${\Delta}$ height Z score/year did not show a significant correlation with the cumulative doses of CsA, but was negatively correlated with the cumulative dose of GC and positively correlated with the Z score for height at the time of diagnosis. Conclusion: In children with SDNS or SRNS undergoing GC therapy, added CsA treatment may not have harmful effects on linear growth.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.4
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• pp.79-88
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• 1986

A nonlinear cumulative damage theory, which can model the effects of the magnitude and sequence of variable amplitude fatigue loadings, is proposed. The concrete beam specimens are prepared and tested in four-point flexural loading conditions. The variable-amplitude fatigue loadings in two and three stages are considered. The present experimental study indicates that the fatigue failure of concrete is greatly influenced by the magnitude and sequence of applied, variable-amplitude fatigue loadings. It is seen that the linear damage theory proposed by Palmgren and Miner is not directly applicable to the concrete under such loading cases. The sum of the cumulative damage is found to be greater than 1 when the magnitude of fatigue loading is gradually increased and less than 1 when the magnitude of fatigue loading is gradually decreased. The proposed nonlinear damage theory, which includes the effects of the magnitude and sequence of applied fatigue loadings, allows more realistic fatigue analysis of concrete structures.

• Journal of Korean Academy of Nursing
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• v.53 no.4
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• pp.453-467
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• 2023

Purpose: This study investigated the cumulative effects of depressive symptoms on cognitive function over time in community-dwelling older adults. Methods: Data were investigated from 2,533 community-dwelling older adults who participated in the Korean Longitudinal Study of Aging (KLoSA) from the 5th (2014) to the 8th wave (2020). The association between cumulative depressive symptoms and cognitive function was identified through multiple regression analysis. Results: When the multiple regression analysis was conducted from each wave, the current depressive symptoms scores and cognitive function scores were negatively associated, regardless of the waves (B5th = - 0.26, B6th = - 0.26, B7th = - 0.26, and B8th = - 0.27; all p < .001). Further, when all the previous depressive symptoms scores were added as explanatory variables in the 8th wave, the current one (B8th = - 0.09, p < .001) and the previous ones (B5th = - 0.11, B6th = - 0.09, and B7th = - 0.13; all p < .001) were also negatively associated with the cognitive function score. The delta R², which indicates the difference between the model's R² with and without the depressive symptoms scores, was greater in the model with all the previous and current depressive symptoms scores (6.4%) than in the model with only the current depressive symptoms score (3.6%). Conclusion: Depressive symptoms in older adults have a long-term impact. This results in an accumulated adverse effect on the cognitive function. Therefore, to prevent cognitive decline in older adults, we suggest detecting their depressive symptoms early and providing continuous intervention to reduce exposure to long-term depressive symptoms.