• International Journal of Oral Biology
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• 제46권1호
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• pp.1-6
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• 2021

Since the outbreak of coronavirus disease 2019 (COVID-2019), the infection has spread worldwide due to the highly contagious nature of severe acute syndrome coronavirus (SARS-CoV-2). To manage SARS-CoV-2, the development of diagnostic assays that can quickly and accurately identify the disease in patients is necessary. Currently, nucleic acid-based testing and serology-based testing are two widely used approaches. Of these, nucleic acid-based testing with quantitative reverse transcription-PCR (RT-qPCR) using nasopharyngeal (NP) and/or oropharyngeal (OP) swabs is considered to be the gold standard. Recently, the use of saliva samples has been considered as an alternative method of sample collection. Compared to the NP and OP swab methods, saliva specimens have several advantages. Saliva specimens are easier to collect. Self-collection of saliva specimens can reduce the risk of infection to healthcare providers and reduce sample collection time and cost. Until recently, the sensitivity and accuracy of the data obtained using saliva specimens for SARS-CoV-2 detection was controversial. However, recent clinical research has found that sensitive and reliable data can be obtained from saliva specimens using RT-qPCR, with approximately 81% to 95% correspondence with the data obtained from NP and OP swabs. These data suggest that self-collected saliva is an alternative option for the diagnosis of COVID-19.

• Computers and Concrete
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• 제31권1호
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• pp.71-84
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• 2023

In this paper, the effects of the thickness of cubic samples on the tensile strength of concrete blocks were studied using experimental tests in the laboratory and numerical simulation by the particle flow code in three dimensions (PFC3D). Firstly, the physical concrete blocks with dimensions of 150 mm×190 mm (width×height) were prepared. Then, three specimens for each of seven different samples with various thicknesses were built in the laboratory. Simultaneously with the experimental tests, their numerical simulations were performed with PFC3D models. The widths, heights, and thicknesses of the numerical models were the same as those of the experimental samples. These samples were tested with a new tensile testing apparatus. The loading rate was kept at 1 kg/sec during the testing operation. Based on these analyses, it is concluded that when the thickness was less than 5 cm, the tensile strength decreased by increasing the sample thickness. On the other hand, the tensile strength was nearly constant when the sample thickness was raised to more than 5 cm (which can be regarded as a threshold limit for the specimens' thickness). The numerical outputs were similar to the experimental results, demonstrating the validity of the present analyses.

• International Journal of Reliability and Applications
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• 제10권2호
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• pp.81-88
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• 2009

A non-parametric procedure is presented for testing exponentially against used better than aged in convex ordering class (UBAC) of life distributions based on u-test. Convergence of the proposed statistic to the normal distribution is proved. Selected critical values are tabulated for sample sizes 5(5)40. The Pitman asymptotic relative efficiency of my proposed test to tests of other classes is studied. An example of 40 patients suffering from blood cancer disease demonstrates practical application of the proposed test.

• 충청수학회지
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• 제3권1호
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• pp.97-101
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• 1990

For testing a hypothesis $H:{\theta}={\theta}_1$, vs $A:{\theta}={\theta}_2$ (${\theta}_1$ < ${\theta}_2$, we obtain a truncated sequential bayes procedure which minimizes the average sample size between ${\theta}_1$ and ${\theta}_2$.

• International Journal of Reliability and Applications
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• 제9권2호
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• pp.125-140
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• 2008

The new better than used failure rate (NBUFR), Abouammoh and Ahmed (1988), and new better than average failure rate (NBAFR) Loh (1984) classes of life distributions, have been considered in the literature as natural weakenings of NBU (NWU) property. The paper considers testing exponentiality against strictly NBUFR (NBAFR) alternatives, or their duals, based on goodness of fit approach that is possible in life testing problems and that it results in simpler procedures that are asymptotically equivalent or better than standard ones. They may also have superior finite sample behavior. The asymptotic normality are proved. Powers, Pitman asymptotic efficiency and critical points are computed. Dealing with censored data case also studied. Practical applications of our tests in the medical sciences are present.

• 비파괴검사학회지
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• 제37권2호
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• pp.75-83
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• 2017

In this paper, we investigate the capacity of the lock-in infrared thermography technique for the evaluation of non-uniform top layers of a silicon carbide coating with a nickel based superalloy sample. The method utilized a multilayer heat transfer model to analyze the surface temperature response. The modelling of the sample was done in ANSYS. The sample consists of three layers, namely, the metal substrate, bond coat and top coat. A sinusoidal heating at different excitation frequencies was imposed upon the top layer of the sample according to the experimental procedures. The thermal response of the excited surface was recorded, and the phase angle image was computed by Fourier transform using the image processing software, MATLAB and Thermofit Pro. The correlation between the coating thickness and phase angle was established for each excitation frequency. The most appropriate excitation frequency was found to be 0.05 Hz. The method demonstrated potential in the evaluation of coating thickness and it was successfully applied to measure the non-uniform top layers ranging from 0.05 mm to 1 mm with an accuracy of 0.000002 mm to 0.045 mm.

• 한국임상수의학회지
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• 제29권1호
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• pp.58-62
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• 2012

To protect aquatic animal health of importing countries from the potential risks associated with exotic diseases introduced through international trade of live aquatic animals, inspection of designated commodities at ports of entry is a critical component of the safeguarding system. The only way to be 100% confident that no fishes in a shipment are infected with a specific agent is to test every fish in the commodity imported with a perfect diagnostic test. For the majority of cases, this is unrealistic since the group of interest may very large particularly for aquatic animals, or imperfect tests are often available. It is, therefore, more common to test a fixed proportion of a group by preplanned sampling schemes. However, decision making based on results of testing the sample can provide quite a chance that infected groups may be misclassified as uninfected, depending on sampling strategy employed. The objective of this study was to determine the possibility that one or more fishes in the group imported being infected but tests negative after inspecting samples. This question is critical to government authorities to examine whether sampling plan is sufficient to achieve the purpose intended for. At fixed population size, the maximum number of infected fishes when all tests negative was decreased as the sampling fraction increased. The probability of including at least one undetected but infected fish in a group for negative tests increased with the number of fish tested or true prevalence. The risk was much lesser where high sensitivity test was assumed; when increasing test sensitivity from 0.9 to 0.99, this risk was dramatically reduced to about a tenth or a fourth for prevalence ranges from 2 to 10%, given sample size ranges from 10 to 200. Based on the preliminary analysis, the author concluded that current sampling plan testing 4-8% of the import proposal for human consumption still can yield high false negative results. Therefore, from the quarantine inspection point of view, an enforced commodity-specific sampling design that accounts for the cost of testing with an imperfect test at the specified design prevalence is urgent.

• Journal of the Korean Statistical Society
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• 제17권2호
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• pp.61-80
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• 1988

For testing homogeneity of scale parameters aginst ordered alternatives, some nonparametric test statistics based on pairwise ranking method are proposed. The proposed tests are distribution-free. The asymptotic distributions of the proposed statistcs are also investigated. It is shown that the Pitman efficiencies of the proposed rank tests are the same as those of the corresponding two-sample rank tests in the scale problem. A small-sample Monte Carlo study is also performed. The results show that the proposed tests are robust and efficient.

• Communications for Statistical Applications and Methods
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• 제8권3호
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• pp.851-858
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• 2001

Using the normalized sample Lorenz curve which is introduced by Kang and Cho (2001), we propose the test statistics for testing of normality that is very important test in statistical analysis and compare the proposed test with the other tests in terms of the power of test through by Monte Carlo method. The proposed test is more power than the other tests except some cases

• Asian Pacific Journal of Cancer Prevention
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• 제17권sup3호
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• pp.17-22
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• 2016

Colorectal cancer is a major cause of mortality worldwide. Fecal occult blood testing has proven a very effective screening tool for early detection and mortality reduction. The aim of this study was to determine predictors factors related to fecal occult blood testing using the Health Belief Model method among residents of Bushehr, Iran. A cross sectional study was performed on a sample of 600 men and women more than 50 years of age. The sample was selected by a convenience method from patients referred to public and private laboratories throughout the city. Each subject filled out a questionnaire which was designed and developed based on Health Belief Model constructs. Statistical analysis was conducted using ANOVA, T-test, chi-square test, and logistic regression. Fecal occult blood tests were performed on 179 (29.8%) out of 600 subjects, of which 95 patients (58.1%) did a periodic examination test and 84 patients (46.9%) had a doctor's advice for testing. According to the logistic regression model, the perceived barriers (P=0.0, Exp(B)= 0.3), perceived benefits (P<0.01, Exp(B)= 1.9) and self-efficacy (P<0.01, Exp(B)= 1.6) were predictive factors related to occult blood testing among subjects. The results showed that reducing people's perception of barriers to testing, increasing perceived benefits of screening, and reinforcing self efficacy can have major effect in increasing the rate of fecal occult blood screening for colorectal cancer prevention.