• Communications for Statistical Applications and Methods
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• v.30 no.1
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• pp.109-117
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• 2023

Intuitively, a test with more assumptions has greater power than a test with fewer assumptions. This kind of examples are abundant in the nonparametric tests vs corresponding parametric ones. In general, the nonparametric tests are less efficient in terms of asymptotic relative efficiency (ARE) compared to corresponding parametric tests (Daniel, 1990). However, this is not always true. To test equal means under independent normal samples, the usual test involves using the t-distribution with the pooled estimator of the common variance. Adding the assumption of equal sample size, we may derive another test. In this case, two tests using more assumptions were performed for univariate (multivariate) cases. For these examples, it was found that the power function of a test with more assumptions is less than or equal to that of a test with fewer assumptions. This finding can be used as an expository example in master's mathematical statistics courses.

• Structural Engineering and Mechanics
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• v.55 no.4
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• pp.857-869
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• 2015

The aluminum 7075-T6 is known as an alloy widely used in aircraft structural applications, which does not exhibit strain rate sensitivity during dynamic compressive tests. Despite mechanical importance of the material, there is not enough attention to determine appropriate sample dimensions such as a sample diameter relative to the device bar diameter and sample length to diameter (L/D) ratio for dynamic tests and how these two parameters can change mechanical behaviors of the sample under dynamic loading condition. In this study, various samples which have different diameters of 31.8, 25.4, 15.9, and 9.5 mm and sample L/D ratios of 2.0, 1.5, 1.0, 0.5, and 0.25 were tested using Split Hopkinson Pressure Bar (SHPB), as this testing device is proper to characterize mechanical behaviors of solid materials at high strain rates. The mechanical behavior of this alloy was examined under ${\sim}200-5,500s^{-1}$ dynamic strain rate. Aluminum samples of 2.0, 1.5 and 1.0 of L/D ratios were well fitted into the stress-strain curve, Madison and Green's diagram, regardless of the sample diameters. Also, the 0.5 and 0.25 L/D ratio samples having the diameter of 31.8 and 25.4 mm followed the stress-strain curve. As results, larger samples (31.8 and 25.4 mm) in diameters followed the stress-strain curve regardless of the L/D ratios, whereas the 0.5 and 0.25 L/D ratios of small diameter sample (15.9 and 9.5 mm) did not follow the stress-strain diagram but significantly deviate from the diagram. Our results indicate that the L/D ratio is important determinant in stress-strain responses under the SHPB test when the sample diameter is small relative to the test bar diameter (31.8 mm), but when sample diameter is close to the bar diameter, L/D ratio does not significantly affect the stress-strain responses. This suggests that the areal mismatch (non-contact area of the testing bar) between the sample and the bar can misrepresent mechanical behaviors of the aluminum 7075-T6 at the dynamic loading condition.

• The Korean Journal of Nuclear Medicine Technology
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• v.25 no.1
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• pp.41-43
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• 2021

Purpose In nuclear medicine blood tests, hemolysis samples are considered as inappropriate sample and are recommended not to be used for blood test. So, the lab are required to collect the blood again in the blood collection room However, The effect of hemolyzed samples on radioimmunoassay has not studied yet. This study was designed to evaluate effects of hemolysis on radioimmunoassay. Materials and Methods The kit manuals of 23 test items were reviewed to confirm whether hemolyzed samples were used. The subjects were 19 general applicants(male : 9, female : 13) and the samples were collected by each two SST tubes, one tube was obtained by centrifugation normally, and the other was obtained hemolyzed sample by centrifugation after external shock. It has been known that highly hemolyzed samples can affect the test results, so the test was performed using the severe hemolyzed sample. The test was performed for each test item using 23 normal serum and hemolysis serum, and SPSS19 program was used for statistical comparison of the test result. Results There was no significant difference between normal serum and hemolysis serum in 21 of 23 test items, but the results of insulin and C-peptide were significantly different(P<0.05). Conclusion It has been known that hemolysis in blood samples can affect the results of biochemical and hematological test, However, hemolysis effect is relatively low. Similarly, this study showed that hemolysis had not much effect on most of immunological radioimmunoassay except for some tests. Therefore, it is thought that the demand for re-collection due to hemolysis will be reduced in the laboratory, which will improve the work process of the laboratory.

• Korean Journal of Child Studies
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• v.20 no.3
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• pp.325-337
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• 1999

In this intervention study, an experimental group of kindergarten children participated in paper folding activities 2 times per week for 10 weeks while the control group did ordinary art activities. Subjects were 43 five-year-old children enrolled in N and D public kindergartens in Hwa-soon Chonnam province. Data were analyzed with a two-sample t-test. The ability to draw and to manipulate geometric figures increased significantly in the experimental group but there was no difference between the two groups in the discrimination of geometric figures.

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.318-326
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• 2016

The purpose of this study was to analyze differences in toddler teachers' perception and application of the contents of the Standard Educare Curriculum. The participants of this study were 205 toddler teachers in charge of two-year-old children at childcare centers in Jollanamdo. For the survey, a questionnaire was prepared for the purposes of this study based on the contents of the $3^{rd}$ Standard Educare Curriculum. Collected data were analyzed using SPSS 18.0 through frequency analysis, descriptive statistics, paired sample t test, independent sample t test, F test, and Duncan's post hoc test. The results are as follows. First, toddler teachers' perception of the contents of the National Standard Educare Curriculum was high, and the level of understanding was higher than when their academic degree was high. Second, toddler teachers' application of the contents of the Standard Educare Curriculum was relatively high. Third, there was a significant difference between toddler teachers' perception of the contents of the Standard Educare Curriculum and their actual application of the contents.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1647-1650
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• 2017

Bus bars are used in place of cables because they can carry more electrical energy with the same volume of conductors. This paper deals with the electrical properties of ceramic coating material for busbars. A ceramic coated samples were prepared for the electrical properties test. There are two types of samples. One is a sample without degradation, and the other is a sample degraded for 30 days. Four electrical properties tests were carried out in accordance with domestic standards. Four electrical characteristics tests are AC dielectric breakdown, V-t, lighting impulse dielectric breakdown, and discharge arc. Both samples showed excellent electrical properties, and the ceramic coating material is very good insulating materials for bus bar.

• Journal of Korean Academy of Nursing
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• v.39 no.3
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• pp.357-365
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• 2009

Purpose: This study was done to examine the effects of aromatherapy on stress and stress responses in adolescents. Methods: A two-group cross-over design was used for this study. The experimental treatment was aroma essential oil inhalation and the placebo treatment was carrier oil inhalation using a necklace. The sample included 36 female high school students. Fisher's exact test, t-test, and paired t-test using SPSS/WIN program were used to analyze the data. Results: Stress levels were significantly lower when the students received the aroma treatment compared to when they received the placebo treatment. The stress responses except salivary IgA levels were significantly lower when the students received the aroma treatment. Conclusion: Aroma inhalation could be a very effective stress management method for high school students. Therefore, it is recommended that this program be used in clinical practice as an effective nursing intervention for high school students.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.156-156
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• 2011

VPH (Volume Phase Hologram) grating is one of the transmission gratings and is known as its remarkable efficiency (>90%). It has two different densities of gelatins causing interference patterns. The VPH grating is favored in many astronomical instruments these days and also IGRINS, which is up coming near infrared high-resolution spectroscope expected to see the first light next year, uses the VPH grating as its cross-disperser. The infrared astronomical instruments operate at cryogenic temperature (~100K) in order to cut down thermal noise and the optical components of IGIRNS will be operated at 130K. The VPH grating is sandwiched in between fused silica or glass and glued together using optical adhesive. IGRINS is expected to go through 50 times of thermal cycling in 10 years including the performance test and this research is to check whether the physical characteristic such as the adhesion or dichromatic gelatin does not break and change from the several cryogenic thermal cycling. The two identical test gratings provided from Kaiser Optical System, Inc. are used in this test. One VPH grating is cooled down to 100K for 2 hours with maximum dT/dt = 5 and warmed up to the room temperature and another grating is kept stored in the room temperature and used as a control sample. In order to check the change, we inspected the grating with eyes and checked its efficiency and transmission at the room temperature every 10 cycling. From the 40 times of cryogenic temperature cool down cycling, the VPH grating showed no signs of change within the error compared to the control sample. We concluded the VPH grating is durable through several cryogenic thermal cycling.

• Journal of Industrial Convergence
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• v.19 no.5
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• pp.119-128
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• 2021

This study was performed to improve the working conditions of female nurses by comparing their organizational commitment and turnover intention according to the type of work shift they prefer. This study is a descriptive survey study, and data were collected by conducting an online survey of 465 female nurses working in three shifts at seven medical institutions. The collected data were analyzed using SPSS WIN 24.0 in a χ² test, a two-sample independent t-test, a pearson correlation and MANCOVA. The result shows that the group of nurses preferring fixed work shift had higher organizational commitment at higher ages and had higher turnover intention if they had an experience of transferring to another medical institution. The study also found that the group that prefers fixed work shift had lower organizational commitment and higher turnover intention than the group of nurses preferring shift work. The nursing department in hospital should strive to improve the working environment in female nurses by developing various types of work, with an aim to increase the organizational commitment of female nurses preferring fixed work and reduce their turnover.

• Korean Journal of Forensic Psychology
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• v.11 no.1
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• pp.21-36
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• 2020

In P300-based concealed information test (P300 CIT), it evaluates whether the P300 amplitude for the probe is significantly greater than that of the irrelevant to determine if the suspect is telling a lie. An independent sample t-test or a bootstrap method can be used as a statistical test to make that decision. Rosenfeld et al. (2004) used the bootstrap method, claiming that "t tests on single sweeps are too insensitive to use to compare mean probe and irrelevant P300s within individuals" and their method has been accepted to date. The purpose of the study is to evaluate whether the power of t-test is lower than that of the bootstrap method in the P300 CIT. The Monte Carlo study was conducted by using EEG collected from 39 participants. The results showed that the type I error rates of the t-test and the percentile bootstrap method were similar and the power of the percentile bootstrap method was slightly higher than that of the t-test. The type I error rates of the t-test and the percentile bootstrap method were slightly lower than the significance level and the powers of the two tests were also slightly lower than that of the theoretical t-test. On the other hand, the type I error rate and power of the standard error Bootstrap method were the same as those of the theoretical t-test and its power was .012 ~ .081 higher than that of t-test depending on experimental conditions.