• Communications for Statistical Applications and Methods
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• v.22 no.6
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• pp.639-646
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• 2015

We propose simultaneous tests for mean and variance under the normality assumption. After formulating the null hypothesis and its alternative, we construct test statistics based on the individual p-values for the partial tests with combining functions and derive the null distributions for the combining functions. We then illustrate our procedure with industrial data and compare the efficiency among the combining functions with individual partial ones by obtaining empirical powers through a simulation study. A discussion then follows on the intersection-union test with a combining function and simultaneous confidence region as a simultaneous inference; in addition, we discuss weighted functions and applications to the statistical quality control. Finally we comment on nonparametric simultaneous tests.

• Journal of Labour Economics
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• v.33 no.1
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• pp.1-30
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• 2010

Using the College Scholastic Ability Test of year 1995, the paper investigates effects of classroom peers on a student's test scores. It exploits exogenous assignment of students across different classrooms within a school under the leveling policy in 1990s. The empirical results reveal strong impacts of peers on individual students. Negative effects of low-performing peers exceed positive effects of high-performing peers. Such a structure of peer interactions has important implications for ability grouping vs. mixing debates in Korea.

• Communications for Statistical Applications and Methods
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• v.7 no.2
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• pp.563-573
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• 2000

In this thesis, we propose the test statistic for ordered alternatives on c-sample ranked set samples(RSS). The proposed test statistic JRSS is Jonckheere type statistic using the median of the i-th samples in each cycle. We obtained the asymptotic property of the proposed test statistic and the asymptotic relative efficiencies of the proposed test statistic with respect to J SRS which Jonckheere type statistic on simple random samples(SRS). From the simulation works, J RSS is superior to J SRS. We compared the empirical powers of J RSS with respect to U RSS on ranked set sample and U SRS on simple random sample using all samples, which are proposed by Kim, Kim and Lee(1999). The powers of J RSS are nearly the same values when entire sample size is large. J RSS is superior to U RSS. J RSS is simpler than U RSSon calculating process.

• Communications for Statistical Applications and Methods
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• v.8 no.2
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• pp.395-406
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• 2001

In this paper, we propose the test statistic for the umbrella alternatives on c-samples ranked set samples(RSS), where the peak of the umbrella is known. We obtain the asymptotic property of the proposed test statistic and the asymptotic relative efficiencies of the proposed test statistic with respect to U-statistic based on simple random samples(SRS). From the simulation work, we compare the empirical powers of the proposed test statistic with U-statistic based on SRS.

• The Korean Journal of Applied Statistics
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• v.7 no.2
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• pp.79-88
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• 1994

Weighted log rank test is a widely applicable test when one is interested in detecting the differences between two groups. In man clinical trials it is common to see no differences in early experiments and does show significant differences later. We propose new weighted log rank test and illustrate it through an example. We also examine the empirical powers and show that the proposed test is more sensitive to detect late differences.

• Communications for Statistical Applications and Methods
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• v.4 no.3
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• pp.663-676
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• 1997

We obtain the simultaneous unit roots test statistics for both regular and seasonal unit roots in a time series with possible seasonal deterministic trends. The limiting distributions of the proposed test statistics are derived and empirical percentiles of the test statistics are tabulated for some seasonal periods. The power and size of the test statistics are examined for finite samples through a Monte Carlo simulation and Compared with those of the Lagrange multiplier test.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.9
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• pp.818-826
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• 2001

In this study, in-situ performance test of a wet surface finned-tube evaporator of an air source heat pump which has a rating capacity of 20RT is carried out. Since test conditions, such as indoor and outdoor air conditions cannot be controlled to satisfy the standard test conditions, experiments are done with the inlet air conditions as they exist, From the experimental data, air side heat and mass transfer coefficients were calculated by the well known heat and mass transfer analogy and tube-by-tube method. since current procedure underpredicted the experimental sensible heat factor(SHF), a proper empirical parameter was introduced to predict the experimental data with satisfactory results. This study provides the method of evaluating the heat and mass transfer coefficients of a wet surface finned-tube evaporator of which in-situ performance test in necessary.

• Korean Journal of Child Studies
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• v.21 no.4
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• pp.243-257
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• 2000

This empirical test of the efficacy of the literature-based reading instruction was conducted with 63(31 male and 32 female) 2nd grade elementary school children. Subjects in the experimental group had 40-45 minutes literature-based reading instruction twice weekly; those in the control group had only basic text reading. Procedures included a pilot study, pre-test, experimental period, and post-test. Research instruments included the Basic Learning Skill Test(Park et al., 1988), the Qualitative Reading Inventory(Leslie & Caldwell, 1990), and the Elementary Reading Attitude Survey(Mckenna & Kear, 1990). Data were graded and scored by each research question and then analyzed with a t-test of differences between the groups. The experimental group showed higher word recognition, text comprehension, and story grammar strategies than the control group. They also showed more improvement in each of these categories than the control group.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.101-107
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• 1996

In this study, the wedge splitting test (WST) specimens with various strength levels were tested to investigate the fatigue crack growth behavior of concrete. Selected test variables were concrete compressive strength with 2 levels (28 MPa, 60 MPa, 100 MPa) and maximum fatigue loading with 2 levels (75%, 85%). Fatigue testing was preceded by fracture energy test and the crack growth was measured by means of the compliance calibration method, 60 WST specimens were cast for the fatigue test, and 6 companion cylinders ($\phi$100${\times}$ 200 mm) for each batch. In fatigue test, the frequency of loading cycle was 1 Hz, and the minimum fatigue loading level was 5~10 % of ultimate monotonic loading. On the basis of the experimental results, a fracture mechanics-based empirical relationships for fatigue crack growth rate (da/dN-$\Delta$KI relationships) were presented. In addition, the effect of initial notch depth on the fracture energy and the validity of compliance calibration technique for the WST were shown.

• Genomics & Informatics
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• v.2 no.4
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• pp.180-183
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• 2004

Comparative Statistic Module(CSM) provides more reliable list of significant genes to genomics researchers by offering the commonly selected genes and a method of choice by calculating the rank of each statistical test based on the average ranking of common genes across the five statistical methods, i.e. t-test, Kruskal-Wallis (Wilcoxon signed rank) test, SAM, two sample multiple test, and Empirical Bayesian test. This statistical analysis module is implemented in Perl, and R languages.