• The Korean Journal of Applied Statistics
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• v.30 no.4
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• pp.513-528
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• 2017

Statistics are often used to test two samples if they have been drawn from the same underlying distribution. In this paper, we introduce several well-known distribution-free tests to compare distributions and conduct an extensive Monte-Carlo simulation to specify their behaviors. We consider various circumstances of when two distributions vary in (1) location, (2) scale, (3) symmetry, (4) kurtosis, (5) tail weight. A practical guideline for two-sample goodness-of-fit test is presented based on the simulation result.

• Communications for Statistical Applications and Methods
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• v.21 no.1
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• pp.11-22
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• 2014

In this study, we propose a simultaneous test procedure based on the individual - values for each sub-null hypothesis with several well-known combining functions. We then compare the efficiency of our procedure with existing tests by obtaining empirical powers through a simulation study. Finally, we discuss some interesting features related to simultaneous test and point out a misconduct for the simulation study published in the previous work.

• Communications for Statistical Applications and Methods
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• v.26 no.2
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• pp.191-203
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• 2019

The problem of examining how well an assumed distribution fits the data of a sample is of significant and must be examined prior to any inferential process. The observed failure time data of items are often not wholly available in reliability and life-testing studies. Lowering the expense and period associated with tests is important in statistical tests with censored data. Goodness-of-fit tests for perfect data can no longer be used when the observed failure time data are progressive Type II censored (PC) data. Therefore, we propose goodness-of-fit test statistics and a graphical method based on generalized Lorenz curve for PC data from a location-scale distribution. The power of the proposed tests is then assessed through Monte Carlo simulations. Finally, we analyzed two real data set for illustrative purposes.

• Journal of the Korean Statistical Society
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• v.18 no.1
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• pp.38-45
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• 1989

A procedure is considered to the problem of testing whether there exist changes in location at possibly two points in a sequence of independent random variables which are successively drawn from normal population. A test statistics based on modified likelihood ratio is proposed and its asymptotic null distribution is derived through the stochastic process representation. A small sample power comparison is made by Monte Carlo method.

• Communications for Statistical Applications and Methods
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• v.15 no.5
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• pp.709-717
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• 2008

The difference of two one-sided kernel estimators is usually used to detect the location of the discontinuity points of regression function. The large absolute value of the statistic imply discontinuity of regression function, so we may use the difference of two one-sided kernel estimators as the test statistic for testing null hypothesis of a smooth regression function. The problem is, however, we only know the asymptotic distribution of the test statistic under $H_0$ and we hardly expect the good performance of test if we rely solely on the asymptotic distribution for determining the critical points. In this paper, we show that if we adjust the bias of test statistic properly, the asymptotic rules hold for even small sample size situation.

• Journal of the Korean Society of Physical Medicine
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• v.17 no.2
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• pp.95-100
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• 2022

PURPOSE: The purpose of this study was to compare the effect of depending on the location of applying chest expansion resistance exercise on the respiratory muscle strength stroke patients, and to suggest more effective interventions to improve respiratory function in stroke patients in clinical practice. METHODS: A total of 30 subjects were selected and divided into two groups, and chest cage extension resistance exercise was applied to the sternum and rib cage, respectively, and performed for 4 weeks, 3 times a week, for 20 minutes. In order to compare the general characteristics of the study subjects and the homogeneity of the group, the pre-experimental values were analyzed using the independent sample t-test. Paired-sample t-test was used for pre-post value comparison of maximum inspiratory pressure and maximum expiratory pressure in each group. Statistical significance was set to .05. RESULTS: Both the sternum application group and the rib cage application group showed a significant difference in the maximum inspiratory pressure according to the intervention. Also, there was a statistically significant difference in the maximum expiratory pressure in the sternum application group. CONCLUSION: As breathing exercise is important for stroke patients, based on the results of this study, if therapists perform sternal extension resistance exercise or rib extension resistance exercise according to the patient's condition and environment, it can help the breathing function of stroke patients.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.1
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• pp.63-72
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• 2002

The main objective of this study is to propose a practical two-microphone impedance tube method to measure the sound transmission loss for flexible sound isolation sheets without the use of the time-consuming and expensive reverberation room. This method was based on the sound decomposition theory developed by Seybert using the spectral density functions of the incident and reflected sound waves. In order to verify the validity of the experimental results, the measured sound transmission losses from the proposed method were compared with the measured data from the reverberation room method and the calculated data from the theory satisfying the mass law of sound isolation material. The resulted trends of the sound transmission losses versus frequencies for several different sound isolation sheets were almost same for each other and agreed quite well in both methods except at some low frequency region. From the experimental results, it was found that the accuracy of sound isolation capability obtained by two-microphone impedance tube method depends upon the microphone spacing, the distance from the first microphone to the test sample surface and the test sample location.

• The Korean Journal of Applied Statistics
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• v.24 no.6
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• pp.1271-1284
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• 2011

The entropy-based test of fit for the inverse Gaussian distribution presented by Mudholkar and Tian(2002) can only be applied to the composite hypothesis that a sample is drawn from an inverse Gaussian distribution with both the location and scale parameters unknown. In application, however, a researcher may want a test of fit either for an inverse Gaussian distribution with one parameter known or for an inverse Gaussian distribution with both the two partameters known. In this paper, we introduce tests of fit for the inverse Gaussian distribution based on the Kullback-Leibler information as an extension of the entropy-based test. A window size should be chosen to implement the proposed tests. By means of Monte Carlo simulations, window sizes are determined for a wide range of sample sizes and the corresponding critical values of the test statistics are estimated. The results of power analysis for various alternatives report that the Kullback-Leibler information-based goodness-of-fit tests have good power.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.343-363
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• 2017

The objective of this work was finding out the most advisable testing conditions for an effective and robust characterization of the tensile strength (TS) of concrete disks. The independent variables were the loading geometry, the angle subtended by the contact area, disk diameter and thickness, maximum aggregate size, and the sample compression strength (CS). The effect of the independent variables was studied in a three groups of experiments using a factorial design with two levels and four factors. The likeliest location where failure beginning was calculated using the equations that account for the stress-strain field developed within the disk. The theoretical outcome shows that for failure beginning at the geometric center of the sample, it is necessary for the contact angle in the loading setup to be larger than or equal to a threshold value. Nevertheless, the measured indirect tensile strength must be adjusted to get a close estimate of the uniaxial TS of the material. The correction depends on the loading geometry, and we got their mathematical expression and cross-validated them with the reported in the literature. The experimental results show that a loading geometry with a curved contact area, uniform load distribution over the contact area, loads projected parallel to one another within the disk, and a contact angle bigger of $12^{\circ}$ is the most advisable and robust setup for implementation of BT on concrete disks. This work provides a description of the BT carries on concrete disks and put forward a characterization technique to study costly samples of cement based material that have been enabled to display new and improved properties with nanomaterials.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.44 no.6
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• pp.269-274
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• 2018

Objectives: The incidence and patterns of mandibular fractures vary by country and population age. This retrospective study evaluated the etiologies and patterns of mandibular fractures in children. Materials and Methods: The clinical records of 89 children (45 males and 44 females) aged 0 to 12 years who presented with mandibular fractures from July 2012 to June 2016 were retrospectively reviewed. The sex, patient age, site of fracture, etiology of trauma, and monthly variations of the fractures were recorded. Descriptive statistics, the z-test and chi-square test were used for statistical analysis and the P-value was set at <0.05. Results: Eighty-nine children (male-to-female ratio 1.02:1) sustained 131 mandibular fractures. Within the study sample, the 6 to 9 year age group most frequently experienced fractures (47.3%). Falls and road traffic accidents (RTA) were the two most common etiological factors that accounted for 44.9% and 24.7% of cases. The condylar fracture was the most common anatomical location (38.9%) followed by the angle (20.6%), parasymphysis (18.3%), body (15.3%), and symphysis (5.3%). A single fracture (51.7%) was more common than multiple fractures (48.3%). The month-wise distribution of mandibular fractures was fairly constant. Conclusion: The condylar region was the most common anatomic site for fractures; in addition, a fall and RTA were the major etiological factors for mandibular fractures. A single fracture was observed in 51.7% of patients while multiple fracture lines accounted for 48.3% of cases.