• Journal of the Korean Statistical Society
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• v.27 no.2
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• pp.189-195
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• 1998

In this paper, we are concerned with the problem of testing the randomness of the coefficients in a first order autoregressive model. A consistent test based on prediction error is suggested. It is shown that under the null hypothesis, the test statistic is asymptotically normal.

• Communications for Statistical Applications and Methods
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• v.15 no.3
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• pp.403-409
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• 2008

In this paper we show that the peak of the type I error rate of the Oochran-Armitage trend test could be greater than the nominal level when $2\;{\times}\;C$ contingency tables obtained from two multinomial distributions are extremely unbalanced. This result justifies the use of the exact Cochran-Armitage trend test in extremely unbalanced $2\;{\times}\;C$ contingency tables.

• Special Issue of the Society of Naval Architects of Korea
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• 2007.09a
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• pp.74-78
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• 2007

In this paper, the HPMM(Horizontal Planar Motion Mechanism) test is simulated in a numerical towing tank by using a commercial CFD(Computational Fluid Dynamics) code, FLUENT. The results of calculation are compared with those of static drift test or rotating arm test calculated by CFD to verify the results simulated by CFD. Through comparing pure sway test of HPMM test with static drift test and pure yaw test of HPMM with rotating arm test, it is found that HPMM test can be simulated in the numerical towing tank.

• Journal of the Korean Data and Information Science Society
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• v.16 no.3
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• pp.609-620
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• 2005

In the secondary data analysis for categorical data, situations often arise in which the estimated cell variances are available, but not the full matrix of variances. In this case researchers are often inclined to use Pearson-type test statistics for homogeneity. However, for a complex sample observed cell proportions are not distributed as multinomial and Pearson-type test statistic generally is not distributed asymptotically as chi-square distribution. This paper evaluates powers for Wald test and Pearson-type test and the first order corrected test of Pearson-type test for homogeneity. The resulting power curves indicate that as the misspecification effect increases, the amount of inflation of significance level and the loss of power Pearson-type test are getting more severe.

• 대한핵의학회:학술대회논문집
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• 1973.11a
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• pp.58.1-58.1
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• 1973

• Journal of the Korean Society of Systems Engineering
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• v.6 no.1
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• pp.25-32
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• 2010

The Test and Evaluation (T&E) process is an integral part of the Systems Engineering Process. The purpose of Test and Evaluation (T&E) in a system development is to identify the areas of risk to be reduced or eliminated. In this study, when develop aircraft of Civil Aviation with development experience of Military Aircraft, it is that establish Test and Evaluation process. Test and Evaluation for KC-100 small aircraft development can divide to certification test and development test. Certification test is proved compliance about Korea Airworthiness standard (KAS Part 23), through Development Test verify required performance of aircraft. These Test and Evaluation Process is more efficient and optimized.

• Transactions of the KSME C: Technology and Education
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• v.1 no.1
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• pp.115-121
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• 2013

It is greatly expected that the technologies of durability enhancement and evaluation for the core structures of plant facilities, marine plant and bridge constructures will be greatly expanded in the plant industry fields. In this study, the actively ongoing applied cases were tried to be analyzed in the present domestic industry fields through the Ultrasonic Nanocrystalline Surface Modification (UNSM) and Ultrasonic Fatigue Test (UFT) technologies using ultrasonic elastic vibrational energy, and the new application technology to improve the durability of plant industry field, especially plant facilities, marine plant and core weld components of bridge constructures will be presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.8
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• pp.781-785
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• 2015

In this study, a newly developed ultrasonic fatigue test was performed for durability assessment of polyoxymethylene engineering plastic, which has a high crystallization rate and degree of crystallization. Fatigue strength of POM (polyoxymethylene) was performed on a piezoelectric UFT developed by Mbrosia Co., Ltd(1), operating at a high frequency of 20 kHz. The test results showed a fatigue limit of 5.0~6.0 MPa under fatigue testing at R = -1, 20kHz; and, electron microscopy revealed the size effect by risk volume and fractured dimple structure after the coalescence of micro-voids through the crazing effect, which occurs during the failure of a polymer.

• The Research Journal of the Costume Culture
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• v.17 no.2
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• pp.216-224
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• 2009

This study was accomplished to examine the dyeing property and functionality of both cotton and silk fabrics dyed with clove extract. The purpose of this study was to investigate the effects of dyeing property, antibiosis, and sun protection effectiveness for a clove. The study method used in this study was the experimental research to extract dyestuffs from a clove, to treat dyestuffs with a mordant, and then to measure dyeing colorfastness, antibiosis, and sun protection for dyed fabrics. As a result of the test for dyeing colorfastness, in the case of colorfastness to laundry, the degree of discoloration showed grade $1\sim4$ and the degree of pollution showed grade $4\sim5$. Colorfastness to perspiration for both cotton and silk fabrics dyed showed grade $1\sim2$ to $4\sim5$. Colorfastness to sunlight showed grade 2 to $4\sim5$. Colorfastness to rubbing showed grade $3\sim4$ to $4\sim5$. In the colorfastness to dry cleaning, the degree of discoloration showed grade $3\sim4$ and the degree of pollution showed grade $4\sim5$. As a result of the antibiosis test, for the Staphylococcus aureus, both cotton and silk showed the bacteria reduction rate of 99.9% even after five times laundry, and for the Escherichia coli, cotton fabrics showed the bacteria reduction rate of 99.9% only after one time laundry, but silk fabrics showed the bacteria reduction rate of 99.9% even after five times laundry. As a result of the test for sun protection effectiveness, dyed silk fabrics showed the result more excellent than dyed cotton fabrics.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.8
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• pp.4759-4763
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• 2013

Background: Prognostic factors of postoperative early and late recurrence in patients with hepatocellular carcinoma (HCC) undergoing curative resection remain to be clarified. The aim of this study was to identify risk factors for postoperative early (${\leq}$ 2 year) and late (> 2 year) intrahepatic recurrences in patients with single HCCs without macrovascular invasion. Methods: A total of 280 patients from December 2004 to December 2007 were retrospectively included in this study. Intrahepatic recurrence was classified into early (${\leq}$ 2 year) and late (> 2 year) and the Chi-Square test or Fisher's exact test and multivariate logistic regression analysis were performed to determine significant risk factors. Results: During the follow-up, 124 patients had intrahepatic recurrence, early and late in 82 and 42 patients, respectively. Multivariate logistic regression analysis showed that microvascular invasion (p=0.006, HR: 2.397, 95% CI: 1.290-4.451) was the only independent risk factor for early recurrence, while being female (p = 0.031, HR: 0.326, 95% CI: 0.118-0.901), and having a high degree of cirrhosis (P=0.001, HR: 2.483, 95% CI: 1.417-4.349) were independent risk factors for late recurrence. Conclusions: Early and late recurrence of HCC is linked to different risk factors in patients with single HCC without macrovascular invasion. This results suggested different emphases of strategies for prevent of recurrence after curative resection, more active intervention including adjuvant therapy, anti-cirrhosis drugs and careful follow-up being necessary for patients with relevant risk factors.