• 한국ITS학회:학술대회논문집
• /
• 2004.11a
• /
• pp.192-197
• /
• 2004

• Communications for Statistical Applications and Methods
• /
• v.29 no.5
• /
• pp.547-559
• /
• 2022

For a chi-squared test, which is a statistical method used to test the independence of a contingency table of two factors, the expected frequency of each cell must be greater than 5. The percentage of cells with an expected frequency below 5 must be less than 20% of all cells. However, there are many cases in which the regional expected frequency is below 5 in general small area studies. Even in large-scale surveys, it is difficult to forecast the expected frequency to be greater than 5 when there is small area estimation with subgroup analysis. Another statistical method to test independence is to use the Bayes factor, but since there is a high ratio of data dependency due to the nature of the Bayesian approach, the low expected frequency tends to decrease the precision of the test results. To overcome these limitations, we will borrow information from areas with similar characteristics and pool the data statistically to propose a pooled Bayes test of independence in target areas. Jo et al. (2021) suggested hierarchical Bayesian pooling models for small area estimation of categorical data, and we will introduce the pooled Bayes factors calculated by expanding their restricted pooling model. We applied the pooled Bayes factors using bone mineral density and body mass index data from the Third National Health and Nutrition Examination Survey conducted in the United States and compared them with chi-squared tests often used in tests of independence.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.45 no.4
• /
• pp.53-60
• /
• 2022

In a group-testing method, instead of testing a sample, for example, blood individually, a batch of samples are pooled and tested simultaneously. If the pooled test is positive (or defective), each sample is tested individually. However, if negative (or good), the test is terminated at one pooled test because all samples in the batch are negative. This paper considers a queueing system with a two-stage group-testing policy. Samples arrive at the system according to a Poisson process. The system has a single server which starts a two-stage group test in a batch whenever the number of samples in the system reaches exactly a predetermined size. In the first stage, samples are pooled and tested simultaneously. If the pooled test is negative, the test is terminated. However, if positive, the samples are divided into two equally sized subgroups and each subgroup is applied to a group test in the second stage, respectively. The server performs pooled tests and individual tests sequentially. The testing time of a sample and a batch follow general distributions, respectively. In this paper, we derive the steady-state probability generating function of the system size at an arbitrary time, applying a bulk queuing model. In addition, we present queuing performance metrics such as the offered load, output rate, allowable input rate, and mean waiting time. In numerical examples with various prevalence rates, we show that the second-stage group-testing system can be more efficient than a one-stage group-testing system or an individual-testing system in terms of the allowable input rates and the waiting time. The two-stage group-testing system considered in this paper is very simple, so it is expected to be applicable in the field of COVID-19.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.490-493
• /
• 2002

There have to be a pooled procurement in order to control construction in every stage. And we need also efficient supply chains to utilize the process. Researching and developing the method, which make it possible the supply chain management by modeling for Internet-enabled pooled procurement in construction, through breakdown in materials is currently in-progress the inside and out side of country. The objective of this paper is to find a reform while modeling the production process of cable duct moreover understanding the wasting factors in each step.

• Journal of Pharmaceutical Investigation
• /
• v.30 no.3
• /
• pp.191-199
• /
• 2000

Genomics is providing targets faster than we can validate them and combinatorial chemistry is providing new chemical entities faster than we can screen them. Historically, the drug discovery cascade has been established as a sequential process initiated with a potency screening against a selected biological target. In this sequential process, pharmacokinetics was often regarded as a low-throughput activity. Typically, limited pharmacokinetics studies would be conducted prior to acceptance of a compound for safety evaluation and, as a result, compounds often failed to reach a clinical testing due to unfavorable pharmacokinetic characteristics. A new paradigm in drug discovery has emerged in which the entire sample collection is rapidly screened using robotized high-throughput assays at the outset of the program. Higher-throughput pharmacokinetics (HTPK) is being achieved through introduction of new techniques, including automation for sample preparation and new experimental approaches. A number of in vitro and in vivo methods are being developed for the HTPK. In vitro studies, in which many cell lines are used to screen absorption and metabolism, are generally faster than in vivo screening, and, in this sense, in vitro screening is often considered as a real HTPK. Despite the elegance of the in vitro models, however, in vivo screenings are always essential for the final confirmation. Among these in vivo methods, cassette dosing technique, is believed the methods that is applicable in the screening of pharmacokinetics of many compounds at a time. The widespread use of liquid chromatography (LC) interfaced to mass spectrometry (MS) or tandem mass spectrometry (MS/MS) allowed the feasibility of the cassette dosing technique. Another approach to increase the throughput of in vivo screening of pharmacokinetics is to reduce the number of sample analysis. Two common approaches are used for this purpose. First, samples from identical study designs but that contain different drug candidate can be pooled to produce single set of samples, thus, reducing sample to be analyzed. Second, for a single test compound, serial plasma samples can be pooled to produce a single composite sample for analysis. In this review, we validated the issue whether the second method can be applied to practical screening of in vivo pharmacokinetics using data from seven of our previous bioequivalence studies. For a given drug, equally spaced serial plasma samples were pooled to achieve a 'Pooled Concentration' for the drug. An area under the plasma drug concentration-time curve (AUC) was then calculated theoretically using the pooled concentration and the predicted AUC value was statistically compared with the traditionally calculated AUC value. The comparison revealed that the sample pooling method generated reasonably accurate AUC values when compared with those obtained by the traditional approach. It is especially noteworthy that the accuracy was obtained by the analysis of only one sample instead of analyses of a number of samples that necessitates a significant man-power and time. Thus, we propose the sample pooling method as an alternative to in vivo pharmacokinetic approach in the selection potential lead(s) from combinatorial libraries.

• Investigative Magnetic Resonance Imaging
• /
• v.19 no.1
• /
• pp.37-46
• /
• 2015

Purpose: This report compared the diagnostic effectiveness between ultrasmall superparamagnetic iron oxide (USPIO) and gadolinium (Gd) based magnetic resonance imaging (MRI) for differentiation of axillary status in breast cancer patients. Materials and Methods: The present authors performed a meta-analysis of previous studies that compared USPIO or Gd based MRI with histological diagnosis after surgery or biopsy. We searched PubMed, EMBASE, Cochrane Library, ScienceDirect, SpringerLink, Ovid databases and references of articles to identify studies reporting data until December 2013. Pooled sensitivity and specificity were calculated for every study; summary receiver operating characteristic and subgroup analysis was done. Analyses of study quality and heterogeneity were also assessed. Results: There were 14 publications that met the criteria for inclusion in our meta-analysis. USPIO based MRI showed 0.83 (95% CI: 0.75-0.89) and 0.97 (95% CI: 0.94-0.98) for pooled sensitivity and specificity, respectively. Gd based MRI represented pooled sensitivity and specificity of 0.61 (95% CI: 0.55-0.67) and 0.90 (95% CI: 0.87-0.92) for each. Overall weighted area under the curve for USPIO and Gd based MRI were 0.9563 and 0.9051, respectively. Conclusion: USPIO based MRI had a tendency toward high pooled sensitivity and specificity in detection of axillary metastases for breast cancer. This result may mean that USPIO based MRI could be used as complementary modality to differentiate axillary status more precisely, and assist in the decision-making process regarding possible invasive procedures, such as sentinel node biopsy.

• Korea Trade Review
• /
• v.41 no.3
• /
• pp.177-198
• /
• 2016

China has retained economic growth rate of average 9% for more than ten years recently after China introduced capitalistic market economy system in 1979 by Deng Xiaoping. China has attracted foreign direct investment for a long time because it has retained very high economic growth rate, low labor cost, and various policies for foreign investors. This paper tries to analyse the determinants of foreign direct investment inflow after reform-opening of China with empirical analysis methods utilizing each province·city's specific characteristics by using the panel data from 1985 to 2013. For the empirical analysis we use random effect model, fixed effect model, pooled OLS, and random coefficient model. The results by pooled OLS and random coefficient model are presented for the comparison with the main results in the process of research. The research shows the results by fixed effect model are better than those by random effect model after doing Hausman's test. The results shows that GRDP, capital stock, and telecommunication exert a positive relationship with foreign direct investment, while express way variable exerts a negative one. China's education level surprisingly does not attract foreign direct investment even though it is not at a critical level. Therefore, the Chinese government should try to increase national income level as it symbolizes market size; encourage domestic investment; and construct high quality telecommunication infrastructure.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.11 no.1
• /
• pp.48-55
• /
• 2001

The purpose of this study was to evaluate the analytical accuracy and precision of microwave oven digestion/atomi absorption spectrophotometry (AAS) for analyzing airborne chromium collected on mixed cellulose ester membrane (M filter from the work environment, and to compare the accuracy and the precision with those of the National Institute for Occupational Safety and Health (NIOSH) Method #7024 hot plate digestion/AAS method. For this study, field air sample pairs were collected from a electroplating process, and spiked samples in a laboratory were prepared and using these samples. Two digestion methods were comp; and evaluated in terms of recovery rate and bias as indices of accuracy and coefficient of variation as a index of precision. The results and conclusions are as follows. In spiked samples, the accuracies (% mean recoveries) of hot plate/AAS and microwave oven/AAS method were 97.19%, 97.1%, respectively, and the precisions (pooled respectively, and the precisions (pooled coefficient of variance, $CV_{pooled}$) 6.93% and 3.88%, respectively. The biases of hot plate ani microwave oven methods were 4.56 - 14.7% and 2.22 - 7.42% respectively. There was no statistically significant difference between hot plate and microwave oven methods recovery rates of spiked samples (p>0,05). Also, no statistically significant difference was shown among the concentrations of air samples determined by two method (p>0.05). In conclusion, microwave oven/AAS method h excellent accuracy and precision, and advantages such as time-saving and simple procedure in comparison with the classical NIOSH method. Therefore, this method can be use widely to analyze airborne chromium collected on MCE filter from the work environments.

• Asia-Pacific Journal of Business
• /
• v.10 no.4
• /
• pp.87-118
• /
• 2019

The purpose of this study is to examine the effects of person-job fit, which consists of educational fit and skill fit, on employees' intrinsic job satisfaction. To the end, the 10-year balanced panel data of the Korean Labor and Income Panel Study(KLIPS) by the Korea Labor Institute (KLI) for 2008-2017 are utilized. This study analyzes 12,730 observations by 1,273 employees by using fixed effect model, random effect model, and pooled OLS estimation method. The empirical results are as follows: First, it is founded that educational fit and skill fit seem affect job satisfaction positively. Second, the negative effects of over-education are clear and the negative effects of under-education are unclear, while the effects of over-skilled and under-skilled are insignificant statistically. Third, the results imply that the size of effect of over-education on intrinsic job satisfaction is larger than that of the effect of over-skilled. Forth, it is shown that the use of fixed effect model is more effective and trustworthy than that of random effect model and pooled OLS estimation method, implying that the effect size of coefficients which are estimated by pooled OLS method and random effect model are likely over-estimated. The empirical results above imply that firms and employees should focus on solving over-education issue before all in order to enhance employees' job satisfaction and it is needed to monitor regularly whether systemic job assignment process is done based on the employees' educational attainment and skill level and to provide more chances for job re-allocation and job rotation.

• Journal of the Korea Society of Computer and Information
• /
• v.22 no.10
• /
• pp.145-150
• /
• 2017

This study aims to analyze panel data using OECD Health data of 34 years to examine how significant the inequality of income is to the inequality of health. The data was from OECD's pooled Health data of 32 countries from 1980 to 2013. The process of determining analysis model was as follows; First, through the descriptive statistics, we examined averages and standard deviation of variables. Second, Lagrange multiplier test has done. Third, through the F-test, we compared Least squares method and Fixed effect model. Lastly, by Hausman test, we determined proper model and examined effective factor using the model. As a result, rather than Pooled OLS Model, Fixed Effect Model was shown as effective in order to consider the characteristics of individual in the panel. The results are as follows: First, as relative poverty rate(${\beta}=-19.264$, p<.01) grows, people's life expectancy decreases. Second, as the rate of smoking(${\beta}=-.125$, p<.05) and the rate of unemployment (${\beta}=-.081$, p<.01) grows, people's life expectancy decreases. Third, as health expenditure(${\beta}=.414$, p<.01) shares more amount of GDP and as the number of hospital beds(${\beta}=-.190$, p<.05) grows, people's life expectancy increases.