• Journal of Environmental Health Sciences
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• v.36 no.2
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• pp.108-117
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• 2010

In this study, ambient particulate matter ($PM_{2.5}$ and $PM_{10}$) levels were measured and their chemical and physical properties were characterized. Two sites in Gwangju were sampled once a month from December 2008 to November 2009. The annual mean concentrations of $PM_{2.5}$ and $PM_{10}$ were $26.9\;{\mu}g/m^3$ and $46.3\;{\mu}g/m^3$, respectively, in Nongseongdong and $26.1\;{\mu}g/m^3$ and $44.8\;{\mu}g/m^3$, respectively, in Duam-dong. $PM_{2.5}$ levels were 1.8 times higher than the USA Environmental Protection Agency (EPA) national ambient air quality standard for $PM_{2.5}$ ($15\;{\mu}g/m^3$). The average $PM_{2.5}/PM_{10}$ ratio of 0.58 suggested that $PM_{2.5}$ is a significant component of the ambient particle pollution. The order of concentration of metallic elements in $PM_{2.5}$ and $PM_{10}$ was Si > Al > Fe > Zn > Pb > Cu > Mn. Cd was not detected. The earth crustal enrichment factors for Cr, Cu, Pb and Zn in $PM_{2.5}$ were higher than those in $PM_{10}$. When the earth crustal enrichment factors for Cr, Cu, Pb and Zn were higher than 10, this suggested influence from anthropogenic sources. The soil contribution ratios for $PM_{2.5}$ and $PM_{10}$ were 11.3% and 16.4%, respectively, and were higher in the fall and winter. Anions (${SO_4}^{-2}$, ${NO_3}^-$, and $Cl^-$) comprise 28.7% of $PM_{2.5}$ and 21.4% of $PM_{10}$. The correlation coefficient of Zn-Fe, Mn-Cu, Fe-Cu and Fe-Mn in $PM_{2.5}$ was high in the sampling sites, and metallic elements were primarily from anthropogenic sources such as fuel combustion and vehicle emissions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.7 no.1
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• pp.35-39
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• 1978

In order to understand the diets of Gwangju city resident, nutrition survey was carried out through four years from 1974 to 1977. 1. Average intake of nutritional elements for an adult per day was 580. 25gr in 1974, 583.62gr in 1975, 599.13gr in 1976, and 597.72gr in 1977. 2. Average calorie distribution of the nutritional elements per adult per day was 13.51% protein, 4.70% fat and 81.08% carbohydrate in 1974; 11.6% protein, 7.1% fat and 81.3% carbohydrate in 1975; 15.0% protein, 4.9% fat and 80.1 % carbohydrate in 1976; 13.79% protein, 4.3% fat, and 82% carbohydrate in 1977. 3. The ratio of the animal protein to total protein consumed was 20.01% in 1974, 25.89% in 1975, 26.01% in 1976, and 29.38% in 1977. 4. In aspect of calorie, taken-in calorie was 2456.91 cal in 1974, 2515.10 cal in 1975, 2544.58 cal in 1976, and 2519.08 cal in 1977. However most of calorie were lower than the R.D.A. (3000cal). 5. The amount of ingested protein was 78.18 gr in 1974, 87.61 gr in 1975, 89,93 gr in 1976, and 81.65gr in 1977. The amount was higher than the R.D.A. (80gr) except 1974’s protein amount. 6. As for fat consumption, it was 27.18 gr in 1974, 40.96gr in 1975, 29.61gr in 1976, and 25.64gr in 1977. But these values were much lower than the R.D.A. (40gr) except for 1975’s. 7. In aspect of the minerals (Fe, Ca), intake of Ca was 462.34mg in 1974, 400.07 mg in 1975, 488.14 mg in 1976 and 440.95mg in 1977. The consumption of Ca was lower than the R.D.A. (600mg). Fe was 10.27mg in 1974, 8.54mg in 1975, 11.36mg in 1976 and 20.84mg in 1977. Most of them were higher than the R.D.A. (10mg) except 1975. 8. It was found that thiamine and riboflavin were ingested slightly higher than the R.D.A. (1.4mg, vit. $B_1$, 1.6mg, vit. $B_2$). The amount of niacin and ascorbic acid were also higher than the R.D.A. except 15.41mg of niacin in 1975.

• Journal of Environmental Science International
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• v.13 no.12
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• pp.1049-1058
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• 2004

PM10 concentration of total 48 samples collected from 4 sites (the root of Miryang University, Sangnam township Office in Miryang. the root of Changwon elementary school, and Junam reservoir in Changwon) turned out to range from 42.29 to 69.49{\mu}g/m^{3}$, and the average concentration was the root of Changwon elementary school $(69.49{\mu}g/m^{3})$>the root of Miryang university $(58.59{\mu}g/m^{3})$>Junam reservoir $(43.56{\mu}g/m^{3})$>Sangnam township Office $(42.29{\mu}g/m^{3}).> In particular, Junam reservoir, the Clean Area, had a slightly higher value than Sangnam township Office. It was thought although the site was plane and windy without pollutants around. it had a higher concentration value influenced by external factors including bigger population and a northeasterly wind due to a newly-established industrial complex nearby. As for water-soluble ions among PM10 particle collected in Miryang and Changwon area, SO42- accounted for $50{/%}$ and NO3-, was $35{\%}$, and the concentration order was S042->N03->Cl->F-. As for the average concentration of metallic components among PM10 particle collected in Miryang and Changwon area. the root of Changwon elementary school had the AI concentration, Fe concentration and Zn concentration 4 times, 3 times and 1.5 times that of Junam reservoir, respectively. The root of Miryang University had the AI concentration 2 times that of Sangnam township Office, and had Fe concentration and Zn concentration $1.2\~1.5$ times those of Sangnam township Office. When it comes to the relation between metallic elements and meteorological factors in Changwon area, the highest coefficient of correlation was between temperature and humidity with 0.92, and temperature and wind speed turned out in the reverse correlation. The coefficient of correlation between Al and Cr was as high as 0.78. Among metallic elements, the coefficient of correlation between Cu and Pb, Cd, Al were 0.84, 0.85, 0.79, respectively. It is thought that the high coefficient of correlation between Cu and Pb is ascribed to busy traffic and wind in the urban areas, Sammun-dong and Gagok-dong in Miryang. Meanwhile, the coefficients of correlation between Fe and Cu, Al, Zn, Cd, Pb were in the reverse correlation. These coefficients of correlation are attributed to the difference in pollutant sources, rather than difference in pollutant and non-pollutant.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.1
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• pp.67-81
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• 2000

An accurate and efficient numerical method for two-dimensional nonlinear radiation problem has been developed. The wave motion due to a moving body is described by the assumption of ideal fluid flow, and the governing Laplace equation can be effectively solved by the higher-order boundary element method with the help of the GMRES (Generalized Minimal RESidual) algorithm. The intersection or corner problem is resolved by utilizing the so-called discontinuous elements. The implicit trapezoidal rule is used in updating solutions at new time steps by considering stability and accuracy. Traveling waves caused by the oscillating body are absorbed downstream by the damping zone technique. It is demonstrated that the present method for time marching and radiation condition works efficiently for nonlinear radiation problem. To avoid the numerical instability enhanced by the local gathering of grid points, the regriding technique is employed so that all the grids on the free surface may be distributed with an equal distance. This makes it possible to reduce time interval and improve numerical stability. Special attention is paid to the local flow around the body during time integration. The nonlinear radiation force is calculated by the "acceleration potential technique". Present results show good agreement with other numerical computations and experiments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1C
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• pp.65-71
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• 2004

We improved the MLLR speaker adaptation algorithm with reduction of the order of HMM parameters using PCA(Principle Component Analysis) or ICA(Independent Component Analysis). To find a smaller set of variables with less redundancy, we adapt PCA(principal component analysis) and ICA(independent component analysis) that would give as good a representation as possible, minimize the correlations between data elements, and remove the axis with less covariance or higher-order statistical independencies. Ordinary MLLR algorithm needs more than 30 seconds adaptation data to represent higher word recognition rate of SD(Speaker Dependent) models than of SI(Speaker Independent) models, whereas proposed algorithm needs just more than 10 seconds adaptation data. 10 components for ICA and PCA represent similar performance with 36 components for ordinary MLLR framework. So, compared with ordinary MLLR algorithm, the amount of total computation requested in speaker adaptation is reduced by about 1/167 in proposed MLLR algorithm.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.2
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• pp.108-116
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• 2009

The present study introduces a Legendre interpolation function which is capable of analyzing wave transformation effectively in a finite element method. A Lagrangian interpolation function has been mostly used for a finite element method with a higher-order interpolation function. Although this function has an advantage of giving an accurate result with less number of elements, simulation time increases. Calculation time can be reduced by mass lumping, whereas the accuracy of solution is lowered. In this study, we introduce a modified Lagrangian interpolation function, Legendre cardinal interpolation, which can reduce simulation time with keeping up favorable accuracy. Through various numerical simulations using a Boussinesq equations model, the superiority of the Legendre cardinal interpolation function to a Lagrangian interpolation function was shown.

• Steel and Composite Structures
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• v.50 no.5
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• pp.563-581
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• 2024

This paper presents a novel finite element model for the free vibration analysis of variable-thickness functionally graded porous (FGP) microplates resting on Pasternak's medium in the hygro-thermal environment. The governing equations are established according to refined higher-order shear deformation plate theory (RPT) in construction with the modified couple stress theory. For the first time, three-node triangular elements with twelve degrees of freedom for each node are developed based on Hermitian interpolation functions to describe the in-plane displacements and transverse displacements of microplates. Two laws of variable thickness of FGP microplates, including the linear law and the nonlinear law in the x-direction are investigated. Effects of thermal and moisture changes on microplates are assumed to vary continuously from the bottom surface to the top surface and only cause tension loads in the plane, which does not change the material's mechanical properties. The numerical results of this work are compared with those of published data to verify the accuracy and reliability of the proposed method. In addition, the parameter study is conducted to explore the effects of geometrical and material properties such as the changing law of the thickness, length-scale parameter, and the parameters of the porosity, temperature, and humidity on the free vibration response of variable thickness FGP microplates. These results can be applied to design of microelectromechanical structures in practice.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1485-1492
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• 2021

In this study, in order to secure an educational environment for the development of skin beauty subjects using VR based on the learners' awareness of VR, a total of 105 learners' perception of VR, VR experience elements, and the development of VR-using skin beauty subjects, questions about general characteristics were conducted using an online questionnaire. As a result of the survey through frequency analysis, factor analysis, and correlation analysis, the higher the awareness of VR, the higher the educational performance and immersion (p<.01). It was found that awareness and interest were high (p<.001). As for the correlation, the higher the VR-using skin care experience factor, the higher the perception of VR-using skin beauty course development. Therefore, it was confirmed that it is necessary to develop and educate skin beauty subjects using VR in line with learners' expectations and the 4th industrial revolution era. Therefore, in follow-up studies, it is considered that it is necessary to develop and operate VR-based skin beauty subjects.

• Korean Journal of Environmental Agriculture
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• v.4 no.1
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• pp.25-30
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• 1985

In order to characterize relationship between accumulation of cadmium, zinc and lead in soil and soil chemical properties and also to choose a suitable soil extractant for the prediction model of heavy metal content in brown rice, four extractants-0.1 M HCl, 0.1 M $HNO_3$, 0.1 M $NH_4-oxalate$ and 0.001 M 2Na-EDTA, were compared by analyzing 84 soil samples collected from paddy fields adjacent to five zinc-minig sites. Contents of Cd, and Pb in soil increased with Zn content and those of three elements were found to be much higher in surface soil ($0{\sim}15 cm$) than suvsqrface soil ($15{\sim}30 cm$). Contents of these elements in soil were positively correlated with soil pH, but its correlation between extractable heavy metal content and organic matter or CEC varied from region to region. These three elements were negatively correlated with Mg content of soils. The extractability of the metals was in the order 0.1 M $HCI{\geq}0.1 M$ $HNO_3>0.001 M$ 2Na-EDTA>0.1 M $NH_4-oxalate$.

• Steel and Composite Structures
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• v.5 no.2_3
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• pp.181-192
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• 2005

The effective length method for flexural (column) buckling has been used for many decades but its use is somewhat limited in various contemporary design codes to moderately slender structures with elastic critical load factor (${\lambda}_{cr}$) less than 3 to 5. In pace with the use of higher grade steel in recent years, the influence of buckling in axial buckling resistance of a column becomes more important and the over-simplified assumption of effective length factor can lead to an unsafe, an uneconomical or a both unsafe and uneconomical solution when some members are over-designed while key elements are under-designed. Effective length should not normally be taken as the distance between nodes multiplied by an arbitrary factor like 0.85, 1.0, 2.0 etc. Further, the classification of non-sway and sway-sensitive frames makes the conventional design procedure tedious to use and, more importantly, limited to simple regular frames. This paper describes the practical use of second-order analysis with section capacity check allowing for $P-{\delta}$ and $P-{\Delta}$ effects together with member and system imperfections. Most commercial software considers only the $P-{\Delta}$ effect, but not member and frame imperfections nor $P-{\delta}$ effect, and engineers must be very careful in their uses. A verification problem is also given for validation of software for this type of powerful second-order analysis and design. It is a trend for popular and advanced national design codes in using the second-order analysis as a norm for analysis and design of steel structures while linear analysis may only be used in very simple structures.