• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.4
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• pp.248-254
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• 1991

The demersal fishes of Asan Bay were collected by an otter trawl in August 1990 to determine optimum sample size for the analysis of community structure. A total of 17 species comprising 957 individuals and 21,840 grams in biomass was collected. Predominant species were Cynoglossus joyneri, Thrissa koreana, Hexagrammos otakii and Johnius belengerii. Coefficients of variation for fish numbers in ten replicate tows ranged from 2.2 to $385.1\%$ for four abundant species and from 52.2 to $162.0\%$ when all species were considered. The cumulative number of species increased rapidly until 4 hauls, and less than 1 species per haul in average was added thereafter. The cumulative diversity index reached nearly an asymptote value when three of samples were combined. Variance in the number of individuals diminished as the sample size increased. The ratio of variance to mean numbers (dispersion index) was not significantly different from the unity when first 4-haul samples were combined. Four of 20-minute trawl haul are proposed to be a proper sampling size for the unbiased estimation of abundance in the study area.

• Journal of the Korean Data and Information Science Society
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• v.4
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• pp.121-130
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• 1993

For the One-way random effects model with unbalanced data, the AOV and MINQUE estimates of variance components are frequently found to be negative. The primary objective of present study is placed on the computation of the probability of the main effect variance component, being negative. The probability of negative estimators from AOV and MINQUE can be obtained by theoretical computation under the normality assumption. It is, however, difficult to compute the probability of negative estimates for these estimators under arbitrary distributions, and hence their probabilities of being negative were computed by simulation experiment in this study. It was shown that there was no significant difference between the theoretical probability under normality and calculated probability by simulation experiment, and that probability of negative estimates decreases as sample size, number of levels and the value of increase.

• Proceedings of the Korean Association for Survey Research Conference
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• 2003.06a
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• pp.34-41
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• 2003

In many cases, the measurement error variances may be functions of the unknown true values or related covariates. This paper develops estimators of the parameters of a linear measurement error variance function based on wi thin-unit sample variaoces. This paper devotes to: (1) define measurement error scale factor $\delta$: (2) develop estimators of the parameters of the 1inear measurement error variance function under stratified multistage sampling design and small error conditions; (3) use propensity methods to adjust survey weights to account for possible selection effects at the replicate level. The proposed methods are applied to medical examination data from the U S Third National Health and Nutrition Examination Survey(NHANES III)

• Korean Journal of Adult Nursing
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• v.21 no.1
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• pp.86-94
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• 2009

Purpose: The purpose of this study was to determine correlates of depression and perceived health status in patients with atrial fibrillation. Methods: The study utilized a descriptive correlational survey design. A convenience sample of 115 subjects were recruited from 3 tertiary medical centers. The data were analyzed by descriptive statistics, hierarchical multiple regression. Results: 1) Study subjects perceived the low frequency of symptoms, relatively high social support, low depression, moderately low physical health, and mental health. 2) The 38% of variance in depression was significantly explained by symptom(${\beta}$ = .49), social support(${\beta}$ = -.21), and education(${\beta}$ = -.17). 3) The 40% of variance in physical health was significantly explained by symptom(${\beta}$ = -.55), social support(${\beta}$ = .16), and education(${\beta}$ = .20). 4) the 12% of variance in mental health was significantly explained by symptom(${\beta}$ = -.26), and social support(${\beta}$ = .24). Conclusion: Most health care providers assume atrial fibrillation patients have very few symptoms. However, symptom related to atrial fibrillation was found to be the most important factors in explaining depression and perceived health status. Additionally, higher social support had great influences on the lower depression and higher perceived health status. Based on the findings of this study, directions for nursing practice and further nursing research for patients with atrial fibrillation are suggested.

• The Korean Journal of Applied Statistics
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• v.20 no.1
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• pp.79-89
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• 2007

A test for normality introduced by Arizono and Ohta(1989) is based on fullback-Leibler discrimination information. The test statistic is derived from the discrimination information estimated using sample entropy of Vasicek(1976) and the maximum likelihood estimator of the variance. However, these estimators are biased and so it is reasonable to make use of unbiased estimators to accurately estimate the discrimination information. In this paper, Arizono-Ohta test for normality is improved. The derived test statistic is based on the bias-corrected entropy estimator and the uniformly minimum variance unbiased estimator of the variance. The properties of the improved KL test are investigated and Monte Carlo simulation is performed for power comparison.

• Clinical and Experimental Reproductive Medicine
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• v.49 no.3
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• pp.196-201
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• 2022

Objective: This prospective consecutive study investigated the variation in sperm DNA fragmentation (SDF) in multiple semen samples from patients with cancer. Methods: Eighty-one patients with various cancers underwent multiple semen collections on 3 consecutive days for sperm cryopreservation prior to cancer treatment. A commercial Halosperm kit was used to measure SDF. Within- and between-subject coefficients of variation were estimated via random-effects analysis of variance to assess the consistency of semen parameters and SDF. Intraclass correlation coefficients (ICCs) were calculated to assess the magnitude of the between-subject component of variance relative to the total variance. Results: The volume of semen in the day-2 and day-3 samples was significantly lower compared with the day-1 sample. Most parameters showed high ICC values, suggesting that within-subject fluctuations were small relative to the between-subject variability. The highest ICC values were identified for the SDF (ICC, 0.68; 95% confidence interval [CI], 0.45-0.84) and semen volume (ICC, 0.67; 95% CI, 0.45-0.84). Conclusion: Our findings showed that repeated ejaculates from patients with cancer had stable SDF levels.

• Clinics in Shoulder and Elbow
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• v.25 no.3
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• pp.173-181
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• 2022

Background: Healing of the tendon itself is not always related to successful clinical outcomes after rotator cuff repair. It was hypothesized that certain radiologic factors affecting clinical outcomes could exist in case of the retear after arthroscopic rotator cuff repair (ARCR) and the radiologic factors could help predict clinical process. The purpose of this study was to identify the radiologic factors associated with clinical outcomes of the retear after ARCR. Methods: Between January 2012 and December 2019, among patients with sufficient footprint coverage for ARCR, 96 patients with Sugaya classification 4 or higher retear on follow-up magnetic resonance imaging were included. The association between clinical outcomes such as American Shoulder and Elbow Surgeons (ASES) score, Constant score and range of motion and radiologic variables such as initial tear dimension, retear dimension, variance of tear dimension, critical shoulder angle, acromial index, and acromiohumeral distance was analyzed. Results: Preoperatively, the ASES and Constant scores were 59.81±17.02 and 64.30±15.27, respectively. And at the last follow-up, they improved to 81.56±16.29 and 78.62±14.16, respectively (p<0.01 and p<0.01). In multiple linear regression analysis, the variance of the mediolateral dimension of tear had statistically significant association with the ASES and Constant scores (p<0.01 and p=0.01). Conclusions: In patients with the retear after ARCR, the variance in the mediolateral dimension of tear had significantly negative association with the clinical outcomes. This could be considered to be reference as relative criteria and needed more sample and mechanical study.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.2
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• pp.114-125
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• 2003

This paper proposes multivariate process capability indices (PCIs) for skewed populations using $T^2$rand modified process region approaches. The proposed methods are based on the multivariate version of a weighted standard deviation method which adjusts the variance-covariance matrix of quality characteristics and approximates the probability density function using several multivariate Journal distributions with the adjusted variance-covariance matrix. Performance of the proposed PCIs is investigated using Monte Carlo simulation, and finite sample properties of the estimators are studied by means of relative bias and mean square error.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.40
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• pp.179-186
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• 1996

Previous researches on optimum ALT plans have shown how to find optimum allocation, lowest stress and sample size subject to minimizing the variance of mean life estimate. Those researches have assumed the censoring time constant. But under certain circumstances such assumptions may not be reasonable. In this paper the constraint on constant censoring time is relaxed, and censoring time is considered variable. If all other test parameters remain unvaried, the variance of the mean life estimate reciprocally increases of the censoring time. This idea in this paper extends to the optimum censoring time. Thus, this paper presents the optimal censoring time in such situations, and finds the optimal lowest stress and allocation based on that optimal censoring time.

• Journal of Korean Society for Quality Management
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• v.20 no.1
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• pp.1-10
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• 1992

When we compare different control charting schemes, the average run length of each control chart is usually used. The use of the average run length implies that there is unbounded number of samples or observations. The regression recursive residuals, however, have been applied to the cumulative sum chart to detect whether the mean or variance changes. To implement choice of decision interval, we calculate the probability that certain fixed number of control statistics stay in the in-control state. This probability can be used as the significance level of a test for detecting the change in the residual mean or variance of the data with a finite number of observations.