• The Korean Journal of Applied Statistics
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• v.29 no.7
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• pp.1399-1409
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• 2016

Nonparametric methods in randomized block design were suggested by Friedman (1937) for general alternatives and were also proposed by Page (1963) for ordered alternatives in one-way layout; in addition, K-sample rank tests for umbrella alternatives were suggested by Mack and Wolfe (1981). In this paper, we proposed a nonparametric method of umbrella alternatives for randomized block design using the aligned method proposed by Hodges and Lehmann (1962) to use block information and using placement suggested by Kim (1999). Monte Carlo simulation was also adapted to compare the power of the proposed procedure with previous methods.

• Journal of Korean Society of Transportation
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• v.33 no.3
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• pp.268-275
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• 2015

As Korea is predicted to be a super-aged society in the near future, transport policies that internalize the elderly have also drawn attentions. Even though some studies have examined the travel by the elderly with various motives, it is, however, difficult to find references that deal with the unique spatio-temporal characteristics of senior trips. For example, the models by time period have represented the temporal property while a set of independent variables associated with urban infrastructure have addressed the spatial feature. This study was conducted under a trip attraction model for transit. The result shows that transit facilities, commercial areas, and hospitals are the dominant factors to explain the travel by the elderly, particularly during 09:00-17:00.

• Horticultural Science & Technology
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• v.35 no.4
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• pp.402-409
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• 2017

We performed seed germination tests to investigate the effects of seed sowing orientation on germination viability on peanut (Arachis hypogaea L.) sprouts. Specifically, we assessed the influence of seed sowing orientation on germination rate, seedling weight, and seedling length, as well as the seedling vigor index. The seeds were sown in oak tree sawdust at 3.0 cm depth. Four seed orientations were tested: vertical with the hypocotyl end down, vertical with the hypocotyl end up, horizontal with the hypocotyl end down, and horizontal with the hypocotyl end up. The mean seed germination percentages of the four seed orientations were significantly different (p < 0.01) and ranged from 25 to 91.7%. The vertical orientation with hypocotyl-end-down and hypocotyl-end-up orientations showed the highest (91.7%) and lowest (25%) germination rates, respectively. The vertical orientation with the hypocotyl end down produced the heaviest (4.9 g) seedlings and the longest hypocotyls (4.65 cm). This orientation also produced the longest true leaf + epycotyl (2.15 cm) and had the highest seedling vigor index (197.1). The seedlings had a straight growth pattern, whereas seedlings from seeds sown with the hypocotyl up had an awkward plumular hook shape. Taken together, to produce peanut sprouts, we recommend placing the seeds vertically with the hypocotyl end down because this orientation leads to a high germination rate, high biomass production, and high overall seedling quality.

• The Korean Journal of Applied Statistics
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• v.28 no.3
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• pp.529-540
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• 2015

A cross-over design is frequently used in clinical trials (especially in bioequivalence tests with a parametric method) for the comparison of two treatments. Missing values frequently take place in cross-over designs in the second period. Usually, subjects that have missing values are removed and analyzed. However, it can be unsuitable in clinical trials with a small sample size. In this paper, we compare single imputation methods in a $2{\times}2$ cross-over design when missing values exist in the second period. Additionally, parametric and nonparametric methods are compared after applying single imputation methods. A Monte-Carlo simulation study compares type I error and the power of methods.

• The Korean Journal of Applied Statistics
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• v.31 no.1
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• pp.29-40
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• 2018

There are various reasons for missing values when collecting data. Missing values have some influence on the analysis and results; consequently, various methods of processing missing values have been studied to solve the problem. It is thought that the later point of view may be affected by the initial time point value in the repeated measurement data. However, in the existing method, there was no method for the imputation of missing values using this concept. Therefore, we proposed a new missing value imputation method in this study using clustering in initial time point of the repeated measurement data and the measure of property proposed by Kim and Kim (The Korean Communications in Statistics, 30, 463-473, 2017). We also applied the Monte Carlo simulations to compare the performance of the established method and suggested methods in repeated measurement data.

• The Korean Journal of Applied Statistics
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• v.31 no.5
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• pp.599-610
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• 2018

The method of Mack and Skillings (Technometrics, 23, 171-177, 1981) is a nonparametric multiple comparison method in a randomized block design with replications. This method is likely to result in loss of information because each block is ranked using the average of observations instead of repeated observations. In this paper, we proposed a new nonparametric multiple comparison method in the randomized block model with replications using an alignment method proposed by Hodges and Lehmann (The Annals of Mathematical Statistics, 33, 482-497, 1962) that extend the joint placement method proposed by Chung and Kim (Communications for Statistical Applications and Methods, 14, 551-560, 2007). In addition, Monte Carlo simulation compared the family wise error rate and power with the parametric method and the nonparametric method.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.5
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• pp.39-47
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• 2018

The Dial Algorithm, based on single link based calculation, is unable to reflect cyclic paths arising in actual urban transportation networks. At the same time, redefining the paths more efficiently can, by strict standards, lead to irrational results stemming from reduction in the size of the network to be analyzed. To solve these two problems of the Dial algorithm, the research herein proposes a vine network method applied to a link based Dial Algorithm, in which the original three step alogrithm is modified into a vine network-based three step process. Also, an analysis of two case study networks show feasible replication of the predicted cyclic path, unrealistic flow, and unsteady transit, as well as alleviation of the problem of irrational path allocation.

• Journal of Korean Society of Transportation
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• v.35 no.4
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• pp.292-306
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• 2017

Traffic noise cost can be assessed either by the damage cost approach or by the avoidance cost method. This paper provides an overview of pertinent studies of these two approaches and shows that the damage cost approach is more universal and reliable than the avoidance cost counterpart. This study then investigated three sub-components to address the damage cost framework. First of all, unit value per person exposed to noise per year was calculated. Secondly, the area exposed to noise was determined using noise prediction equation. Thirdly, the number of people affected by noise was computed by multiplying the number of people exposed to noise with the percentage of people affected by noise. This paper also suggested a simplified equation that represents the relationship between damage costs and noise levels. Finally, the benefits of noise reduction derived from the damage cost method and those from the avoidance cost approach were compared and discussed.

• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1349-1357
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• 2013

In clinical research, sample size determination is one of the most important things. There are parametric method using t-test and non-parametric method suggested by Kim and Kim (2007) based on Wilcoxon's rank sum test for determining sample size in non-inferiority trials. In this paper, we propose sample size calculation method based on placements method suggested by Orban and Wolfe (1982) and using the power calculated by Kim (1994) in non-inferiority trials. We also compare proposed sample size with that using Kim and Kim (2007)'s formula and that of t-test for parametric methods. As the result, sample size calculated by proposed method based on placements is the smallest. Therefore, proposed method based on placements is better than parametric methods in case that it's hard to assume specific distribution function for population and also more efficient in terms of time and cost than method based on Wilcoxon's rank sum test.

• The Korean Journal of Applied Statistics
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• v.30 no.6
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• pp.1027-1036
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• 2017

Multiple comparisons are required to confirm whether or not something is significant if the null hypothesis to test whether the difference between more than three treatments is rejected in a one-way layout. There are both parametric multiple comparison method Tukey (1953) and Nonparametric multiple comparison method based on Kruskal-Wallis (1952).This procedure is applied to a mixed sample of all data and then an average ranking is used for each of three or more treatments. In this paper, a new nonparametric multiple comparison procedure based on joint placements for a one-way layout as extension of the joint placements described in Chung and Kim (2007) was proposed. Monte Carlo simulation is also adapted to compare the family wise error rate (FWE) and the power of the proposed method with previous methods.