• Journal of Preventive Medicine and Public Health
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• v.34 no.3
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• pp.262-268
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• 2001

Objectives : To integrate the results of studies which assess an association between blood lead and blood pressure. Methods : We surveyed the existing literature using a MEDLINE search with blood lead and blood pressure as key words, including reports published from January 1980 to December 2000. The criteria for quality evaluation were as follows: 1) the study subjects must have been workers exposed to lead, and 2) both blood pressure and blood lead must have been measured and presented with sufficient details so as to estimate or calculate the size of the association as a continuous variable. Among the 129 articles retrieved, 13 studies were selected for quantitative meta-analysis. Before the integration of each regression coefficient for the association between blood pressure and blood lead, a homogeneity test was conducted. Results : As the homogeneity of studies was rejected in a fixed effect model, we used the results in a random effect model. Our quantitative meta-analysis yielded weighted regression coefficients of blood lead associated with systolic blood pressure and diastolic blood pressure results of 0.0047 (95% confidence interval [CI]: -0.0061, 0.0155) and 0.0004 (95% CI: -0.0031, 0.0039), respectively. Conclusions : The published evidence suggested that there may be a weak positive association between blood lead and blood pressure, but the association is not significant.

• Tunnel and Underground Space
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• v.16 no.1 s.60
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• pp.26-37
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• 2006

This study addresses the applicability of box fractal dimension, $D_B$, as an index of statistical homogeneity of fractured rock mass. The box-count method's capability in quantifying the combined effect of fracture density and size distribution is examined systematically. Total of 129 two-dimensional fracture configurations were generated based on different combinations of fracture size distribution and fracture density. $D_B$was calculated for the generated fracture network systems using the box-counting method. It was found that was standard deviation of trace length and fracture orientation have no effect on calculated $D_B$. The estimated $D_B$ was found to increase with increasing total density and/or mean trace length. To explore the field applicability of this study, the statistical homogeneity of fractured rock mass was investigated at the rock slope and the underground facility using the box-counting method as well as conventional contingency table analysis. The results obtained in this study clearly show that the methodologies given in this paper have the capability of determining the statistical homogeneity of fractured rock mass.

• Journal of Navigation and Port Research
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• v.30 no.8 s.114
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• pp.643-648
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• 2006

The primary purpose of this study is to examine empirically the effect of foreign crew's cultural and organizational characteristics on their self-efficacy and organization commitment. Currently, the restrictions on the employment of the foreign crews are being eased in the Korean shipping industry and many problems are occurring consequently. However, specific and empirical studies on the relevancy of cultural characteristics to the crew's self-efficacy and organizational commitment on board the vessels with combined crews have not yet been carried out. To solve these problems, we examined how the cultural characteristics such as acculturation and accommodation of different culture related to the improvement of cultural homogeneity of vessels with combined crews influence on the self-efficacy, job satisfaction and organizational commitment of the foreign crews through SEM analysis. According to the results, hypothesis 1 and 2 were all supported with statistical significance. To conclude, this study suggests that foreign crew's cultural homogeneity and their self-efficacy should be firstly enhanced in order to improve organizational commitment on the vessel with combined crews. Furthermore, a study on self-efficacy of crew organization is urgently needed to enhance the effectiveness of an organization in a vessel with combined crews that has special environment. The result of this study will contribute a lot to the organization management of a vessel with combined crews.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.4
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• pp.471-476
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• 2015

Purpose: We have analyzed the transmittance distribution of various ocular lenses using local transmittance microscope to investigate the optical homogeneity of the lens. Methods: The local transmittance of the laser which is focused on the surface of the spectacle lens was measured by using the photo-detector, lock-in amplifier and motorized-stage. 25 multi-coated lenses with non-tinted of 5 groups and 45 multicoated lenses with tinted of 9 groups were analyzed as a sample respectively. Results: Average and deviation of local transmittance for nontinted lenses were measured almost uniformly with various refractive index and coating. However, deviation of transmittance of for tinted lenses was analyzed as about 3.7 times larger than that of non-tinted lenses. Inhomogeneity of local transmittance of for tinted lenses was also analyzed as about 3.1 times larger than that of non-tinted lenses. Conclusions: We could analyze that standard deviation of transmittance and inhomogeneity of local transmittance of for tinted lenses is larger than that of non-tinted lenses using the local transmittance microscope. These analysis using local transmittance microscope can be utilized as a way to evaluate lens performance and improve optical homogeneity.

• Journal of Integrative Natural Science
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• v.7 no.3
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• pp.208-213
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• 2014

National-wide and/or large scale sample surveys generally use complex sample design. Traditional Pearson chi-square test is not appropriate for the categorical complex sample data. Rao-Scott suggested an adjustment method for Pearson chi-square test, which uses the average of eigenvalues of design matrix of cell probabilities. This study is to compare the efficiency of Rao-Scott first order adjusted test to Wald test for homogeneity between two populations using 2009 Gyeongnam regional education offices's customer satisfaction survey (2009 GREOCSS) data. The 2009 GREOCSS data were collected based on stratified three-stage cluster sampling with probability proportional to size. The empirical results show that the Rao-Scott adjusted test statistic using only the variances of cell probabilities is very close to the Wald test statistic, which uses the covariance matrix of cell probabilities, under the 2009 GREOCSS data based. However it is necessary to be cautious to use the Rao-Scott first order adjusted test statistic in the place of Wald test because its efficiency is decreasing as the relative variance of eigenvalues of the design matrix of cell probabilities is increasing, specially more when the number of degrees of freedom is small.

• Journal of Integrative Natural Science
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• v.5 no.4
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• pp.241-245
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• 2012

Categorical data collected based on complex sample design is not proper for the standard Pearson multinomial-based chi-squared test because the observations are not independent and identically distributed. This study investigates effects of bias of point estimator of population proportion and its variance estimator to the standard Pearson chi-squared test statistics when the sample is collected based on complex sampling scheme. This study examines the effect under two population homogeneity test. The standard Pearson test statistic can be partitioned into two parts; the first part is the weighted sum of ${\chi}^2_1$ with eigenvalues of design matrix as their weights, and the additional second part which is added due to the biases of the point estimator and its variance estimator. Our empirical analysis shows that even though the bias of point estimator is small, Pearson test statistic is very much inflated due to underestimate the variance of point estimator. In the connection of design-based variance estimator and its design matrix, the bigger the average of eigenvalues of design matrix is, the larger relative size of which the first component part to Pearson test statistic is taking.

• The Research Journal of the Costume Culture
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• v.9 no.4
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• pp.664-676
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• 2001

This study highlights the homogeneity in the heritage of the costume cultures between the Gulf of Aden, a part of the Horn region of Africa and the Arab region of West. Asia. Specifically, a cross-cultural perspective is used to examine the similarities between the two regions based on their (1) geographic living cultures and (2) the use of a costume accessory called Burga-a face veil. The current trend in research on the traditional costume culture of Africa mostly ties art with the traditional costume culture and examines its from an aesthetic or animalism perspective rather than from a cross cultural Perspective. Compared to Previous research in this area this study used literature reviews and Pictorial analysis to analyze costume cultures from a cross-cultural perspective. The Burga, which is worn in the low lands of the Horn region, which is located between the West Asia and African continents, as well as the Arab region, shows a reciprocal cultural exchange between the two regions. Similarities can be found in the shape, design, decorative elements, and the way the Bursa was worn in two regions. Although the Burga as a face veil is only a small part of a costume, it reaffirms the similar living cultures and geographic characteristics of the two regions. As the living culture environment becomes similar around the world, this study should help with cross culture negotiations as well as forther the development of traditional costume research.

• International Journal of Industrial Entomology and Biomaterials
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• v.6 no.1
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• pp.63-68
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• 2003

We investigated the sequence divergence of the geographic samples of the queen bumble bee (Bombus ardens) in Korea. A portion of mitochondrial COI gene sequences (423 bp) was analyzed for 44 individuals collected from seven localities. Sequence analysis resulted in four COI haplotypes with the maximum nucleotide divergence of only 0.5% (two bp). One haplotype (BA1) was dominant in all localities surveyed (86.4%). The finding of low sequence divergence and dominance of one haplotype appear to reflect, although limited, the life history of the B. ardens queens subjected to active dispersal and seasonal fluctuation in queen number.

• Structural Engineering and Mechanics
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• v.56 no.1
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• pp.137-156
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• 2015

In this paper, an analytical solution of displacement, strain and stress field for rotating thick-walled cylinder made of functionally graded material subjected to the uniform external magnetic field and thermal field in plane strain state has been studied. Stress, strain and displacement field as a function of radial coordinates considering magneto-thermo-elasticity are derived analytically. According to the Maxwell electro-dynamic equations, Lorentz force in term of displacement is obtained in cylindrical coordinates. Also, symmetric temperature distribution along the thickness of hollow cylinder is obtained by solving Fourier heat transfer equation in cylindrical coordinates. Using equation of equilibrium and thermo-mechanical constitutive equations associated with Lorentz force, a second-order inhomogeneous differential equation in term of displacement is obtained and will be solved analytically. Except Poisson's ratio, other mechanical properties such as elasticity modulus, density, magnetic permeability coefficient, heat conduction coefficient and thermal expansion coefficient are assumed to vary through the thickness according to a power law. In results analysis, non-homogeneity parameter has been chosen arbitrary and inner and outer surface of cylinder are assumed to be rich metal and rich ceramic, respectively. The effect of rotation, thermal, magnetic field and non-homogeneity parameter of functionally graded material which indicates percentages of cylinder's constituents are studied on displacement, Von Mises equivalent stress and Von Mises equivalent strain fields.

• Journal of Powder Materials
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• v.5 no.4
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• pp.250-257
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• 1998

The synthesis of titanium silicides ($Ti_3Si$, $TiSi_2$, $Ti_5Si_4$, $Ti_5Si_3$ and TiSi) by mechanical alloying has been investigated. Rapid, self-propagating high-temperature synthesis (SHS) reactions were observed to produce the last three phases during room-temperature high-energy ball milling of elemental powders. Such reactions appeared to be ignited by mechanical impact in an intimate, fine powder mixture formed after a critical milling period. During the high-energy ball milling, the repeated impact at contact points leads to a local concentration of energy which may ignite a self-propagating reaction. From in-situ thermal analysis, each critical milling period for the formation of $Ti_5Si_4$, $Ti_5Si_3$ and TiSi was observed to be 22, 35.5 and 53.5 min, respectively. $Ti_3Si$ and $TiSi_2$, however, have not been produced even till the milling period of 360 min due to lack of the homogeneity of the powder mixtures. The formation of titanium silicides by mechanical alloying and the relevant reaction rates appeared to depend upon the critical milling period, the homogeneity of the powder mixtures, and the heat of formation of the products involved.