• Journal of the Korea Furniture Society
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• v.23 no.2
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• pp.152-162
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• 2012

The color changing of the wood surface was tested by accelerated weathering test that can simulate the outdoor condition with short period. In early parts of accelerated weathering test, weight and volume of specimen all were increased due to the moisture evaporation by its high temperature and illumination level, but weight and volume of specimen all were decreased from middle parts to last. However, significancy showed between control group and accelerated weathering test group in terms of weight and volume. According to the results of color-difference meter, in the early parts of the accelerated weathering test lightness, redness and yellowness all showed a clear increasing or decreasing trend. However, after three weeks all values were almost never change. Until the early parts of the test, lightness was decreased and there was not a considerable change after three weeks in the test. Redness showed a some change in early parts of the test, but this also showed not great change after middle parts of the test as like lightness. Yellowness also showed same pattern. These results could be verified through the visual inspection. As like weight and volume, significancy showed between control group and accelerated weathering test group in terms of color-difference test. In all accelerated weathering test group, color-differences of after test was lower than that of before test. To correctly analyze this cause, more additional research will be need on each of temperature, humidity and illumination factors.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.551-553
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• 2002

The cubicle type GIS rated at 25.8kV has been designed and manufactured by Jinkwang E&C eacently with their own technologies and KERI's assistances. The C-GIS has been tested to check the design capability for reference before conducting the type test. The operating characteristics test, short time withstand current and peak withstand current test, basic short circuit test duty T60 for preconditioning test, cable charging current switching test, capacitor bank current switching test, basic short circuit test duty T100s and T100a, single phase earth fault test, double earth fault test has been conducted. The test results show that the design and the manufacturing of the C-GIS has an enough capability to pass through the type test except the occurrence of 2 NSDDs in the cable charging current switching test and the instability of opening time at the minimum operating voltage. The problems shown in the tests will be improved soon and the successful pass will be expected in the following type test.

• Journal of Integrative Natural Science
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• v.12 no.3
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• pp.91-99
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• 2019

Many researchers in various study fields use the two sample t-test to confirm their treatment effects. The two sample t-test is generally used for small samples, and assumes that two independent random samples are selected from normal populations, and the population variances are unknown. Researchers often conduct F-test, the test of equality of variances, before testing the treatment effects, and the test statistic or confidence interval for the two sample t-test has two formats according to whether the variances are equal or not. Researchers using the two sample t-test often want to know how large sample sizes they need to get reliable test results. This research gives some guidelines for sample sizes to them through simulation works. The simulation had run for normal populations with the different ratios of two variances for different sample sizes (${\leq}30$). The simulation results are as follows. First, if one has no idea equality of variances but he/she can assume the difference is moderate, it is safe to use sample size at least 20 in terms of the nominal level of significance. Second, the power of F-test for the equality of variances is very low when the sample sizes are small (<30) even though the ratio of two variances is equal to 2. Third, the sample sizes at least 10 for the two sample t-test are recommendable in terms of the nominal level of significance and the error limit.

• Journal of the Korean Data and Information Science Society
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• v.15 no.2
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• pp.485-493
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• 2004

This paper considers the test of money and income causality. Jeong (1991, 2003) developed a nonparametric causality test based on the kernel estimation method. We apply the nonparametric test to USA data of money and income. We also compare the test results with ones of the conventional parametric test.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.31-36
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• 2003

In this study a relationship between SP curves and tensile properties was investigated by FE analysis on SP test with various assumed tensile properties. For the accuracy of FE analysis, SP test and tensile test were performed and those results were compared with FE analysis results. The yield load(Py) defined from the intersection point of two lines tangent to the elastic bending region and plastic bending region. And it was related specifically with yield stress(${\sigma}_0$) in FE analysis result curves. The slopes of FE analysis result curves normalized by yield stress(${\sigma}_0$) reflected the change of tensile properties regardless of yield stress(${\sigma}_0$) variation. Empirical relations were derived from these results. Tensile properties from these relations showed good agreement in FE analysis curve and tested curve.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.151-154
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• 2004

The HANARO, a multi-purpose research reactor of 30 MWth open-tank-in-pool type, has been under normal operation since its initial criticality in February, 1995. Many experiments should be safely performed to activate the utilization of the HANARO. A flow simulated test facility has been developed for the verification of structural integrity of those experimental facilities prior to loading In the HANARO. This test facility is composed of three major parts; a half-core structure assembly, flow circulation system and support system. The half-core structure assembly is composed of plenum, grid plate, core channel with flow tubes, chimney and dummy pool. The flow channels are to be filled with flow orifices to simulate similar flow characteristics to the HANARO. This paper describes an analysis of the flow distribution of the cote channel and compares with the test results. As results, the analysis showed similar flow characteristics compared with those in the test results.

• Journal of the Korea Concrete Institute
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• v.11 no.3
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• pp.23-34
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• 1999

In designing PSC box girder bridge, the dead load, prestressing force, creep and shrinkage of concrete are the main factors which influence the camber and deflection of segmental concrete structure under construction. Among these factors the creep and shrinkage are the functions of the time-dependent property which, therefore, must considered with time. The prediction model for estimating creep and shrinkage of concrete has been suggested by ACI, CEB/FIP, JSCE and KSCE design code. In this study the creep and shrinkage test were carried out for four curing ages of concrete which was applied to the pretressed concrete box-girder bridge at a construction site, and the results of test were compared to the values of prediction by the design code. Shrinkage test shows that the test results are similar to KSCE-96 and JSCE-96 but very higher than other prediction model and creep test results are generally similar to ACI-209 and DSCE-96 but lower than other prediction models in contrast to shrinkage test.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.601-604
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• 2006

Reinforcement corrosion is the most important durability problem of reinforced concrete structures. One of the important factors affecting the steel corrosion is carbonation. However, existing carbonation test takes several months to obtain the results. Therefore, in this study, new rapid carbonation test equipment for concrete was developed and its applicability was investigated. The testing period can be reduced by increasing $CO_2$ concentration up to 100% in the equipment. It is found from the test results that the carbonation depth of concrete specimens tested for 2 weeks was $3{\sim}5$ times greater than that of specimens tested by existing test method. In conclusion, it would be possible to get the reliable test results enough to evaluate the durability of concrete structures in a short-period.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.4
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• pp.17-27
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• 2020

In this paper, we proposed verification methods to prove the effectiveness of automatic test equipment (ATE) for weapon systems. Since the test results from the unproven ATE is not reliable and its use is limited as objective data, it is essential to verify the test equipment in order to guarantee the quality level of the unit under test (UUT). Through the suggested methods, it is applied to the ATE of the tactical information communications network (TICN) system to confirm the verification results and to describe the validation results.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.423-428
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• 2006

Twenty nine HRV models have been tested for last two years since the attestation system has been started by KARSE. It is the objective of the present study to analyze the performance test results. Uncertainty analysis has been conducted to find the effects of measured variables on the uncertainties of test results. The uncertainty of enthalpy is found to be affected by the uncertainty of wet bulb temperature significantly, but not by that of dry bulb temperature for the present range of parameters. The uncertainty of effective enthalpy efficiency is calculated to be 6%P for the cooling condition, and 3%P for the heating condition approximately. In order to reduce the uncertainty of the test results, the uncertainty of wet bulb temperature should be minimized and the indoor/outdoor test conditions should be modified so as to increase the enthalpy difference.