• Steel and Composite Structures
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• v.50 no.3
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• pp.299-318
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• 2024

The main objective of this paper is to compute the far-field acoustic radiation (sound radiation) of functionally graded plates (FGM) loaded by sinusoidally varying point load subjected to the arbitrary boundary condition is carried out. The governing differential equations for thin functionally graded plates (FGM) are derived using classical plate theory (CPT) and Rayleigh integral using the elemental radiator approach. Four cases, segregated on power-law index k=0,1,5,10, are studied. A novel approach is illustrated to compute sound fields of vibrating FGM plates using the physical neutral surface with an elemental radiator approach. The material properties of the FGM plate for all cases are calculated considering the power law indexes. An in-house MATLAB code is written to compute the natural frequencies, normal surface velocities, and sound radiation fields are analytically calculated using semi-analytical formulation. Ansys is used to validate the computed sound power level. The parametric effects of the power law index, modulus ratios, different constituent of FGM plates, boundary conditions, damping loss factor on the sound power level, and radiation efficiency is illustrated. This work is the benchmark approach that clearly explains how to calculate acoustic fields using a solid layered FGM model in ANSYS ACT. It shows that it is possible to asymptotically stabilize the structure by controlling the intermittent layers' stiffness. It is found that sound fields radiated by the elemental radiators approach in MATLAB, ANSYS and literatures are in good agreement. The main novelty of this research is that the FGM plate is analyzed in the low-frequency range, where the stiffness-controlled region governs the whole analysis. It is concluded that a clamped mono-ceramic FGM plate radiates a lesser sound power level and higher radiation efficiency than a mono-metallic or metal-rich FGM plate due to higher stiffness. It is found that change in damping loss factor does not affect the same constituents of FGM plates but has significant effects on the different constituents of FGM plates.

• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.215-222
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• 2001

A statistical analysis was performed to evaluate relationships among the pollutant concentrations in non-urban area. The data obtained from two subcatchments in Hwa-Ong watershed during 1999 was used for correlation and regression analyses. Strong correlations were observed among the SS, COD, and TP, while it was not significant with TN. The reason fer weak correlation with TN might be that TN was high in dry-days and runoff in wet-days could not increase enough to change it substantially like in other pollutants. The correlations were stronger for the data in wet-days than in dry-days, and it was influenced by watershed characteristics. While TP-COD showed linear relationship from the regression analysis, SS-TP and SS-COD shelved intrinsically linear relationship between log-transformed TP and COD data and non-transformed SS data. The TP-COD showed strong relationship for all the combinations of monitored data, which implies that these two constituent concentrations varied in a similar pattern. The regression equations reported in the paper might be used to estimate one pollutant concentration from the other in pollutant loading estimates, and its application could be expanded to other non-urban watersheds if their characteristics are not significantly different from the study area. In water quality management projects, rigorous monitoring and its thorough evaluation are recommended to develop more reliable relationships among the pollutant concentrations which could be used in other area.

• Economic and Environmental Geology
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• v.36 no.6
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• pp.415-429
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• 2003

This study was objected to identify the difference of water quality and the characteristics of water contamination in adjacent bed-rock areas of Upper Hwajeonni and Guryongsan Formations in Miwon, Choongchungbuk-do, Korea. Water samples showed mainly (Ca, Mg)-$HCO_3$ type in Upper Hawjeonni Formation and (Ca, Mg)-$SO_4$ and (Ca, Mg)-$HCO_3$ types in Guryongsan Formation indicating the enrichment of $SO_4$ in major compositions. Groundwater quality could be divided into two groups based on the major weathering processes, implied by the ratio of bicarbonate to silica. Carbonate-silicate weathering predominates in Upper Hwajeonni Formation, and silicate weathering in Guryongsan Formation. Stream-water quality also appeared to be controlled by water-rock interaction. Cluster analysis identified three groups of groundwater and four groups of stream-water with distinctive geochemical characteristics. The results of factor analysis indicated that the levels of each chemical constituent in water samples derived from both natural weathering reactions and anthropogenic contamination sources. To delineate the pollution potential of water resources, Modified Pollution Index(M.P.I.) was developed. M.P.I. scores of water samples ranged from -0.08 to 0.18, with mostly positive along the rock quarry in Guryongsan Formation areas. M.P.I. scores appeared to be a useful predictor of metal contamination of water resources.

• Journal of Environmental Health Sciences
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• v.15 no.2
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• pp.11-23
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• 1989

This study was performed to investigate present water quality and pollution characteristics of them in the basin area of the Mankyung river near Chonju urban stream. In order to obtain the pollution characteristics of this investigation, the physio-chemical water analysis as temperature, pH, DO, BOD, Cd, Cu, Pb and Zn, and coliform group and their correlation analysis were determined from March to August 1988. The main results were summarized as follows 1. Each chemical constituent detected in three streams has the following variation range as pH(6.7-7.3), DO(1.3-8.9 mg/l), BOD(1.6-162.5mg/l) and water temperature was dominated by atmospheric temperature. 2. In three streams, concentration range of heavy metal was Cd N.D.-2.8 $\mu$g/l, Cu 1.1-10.2 $\mu$g/l, Pb 2.1-13.2 $\mu$g/l and Zn 25.6-62.2 $\mu$g/l, and was shown the order of Zn, Pb, Cu and Cd. 3. In the investigation on the bacteriological pollution-in the three streams. 1) The average number of general bacteria contaminated in the Chonju urban stream was $1.7 \times 10^{5}$ numbers/ml, which was higher than $2.6 \times 10^{2}$ numbers/ml, in the Gosan stream and 1.6 $\times$ 10 numbers/ml in the Mankyung river. 2) The average number of total coliform, fecal coliform and fecal streptococcus contaminated in the Chonju urban stream which was the highest polluted site than those of the other sampling sites were respectively $2.1 \times 10^{5}$, $2.1 \times 10^{5}$ and $9.6 \times 10^{4}$ MPN/100ml. 4. Correlation coefficient between GB and TC in the Chonju stream, Gosan stream and Mankyung river was respectively 0.99, 0.96 and 0.99, Correlation coefficient between TC and FC in Chonju stream, Gosan stream and Mankyung river was respectively 0.99, 0.97 and 0.99 and correlation coefficient between FC and TC was respectively 0.99, 0.91 and 0.99. This results mean positively dose relationship between them. 5. The occupied percentage of FC of TC in the Chonju stream, Gosan stream and Mankyung river was respectively 88.1%, 68.4% and 77.9% and the percentage of Tc of TS was respectively 43.5%, 31.6% and 41.4%. These .results was considered indicative of pollution derived from domestic wastes which had been contaminated by the feces of inhabitants and domestic animals.

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1178-1183
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• 1999

Essential oils were isolated from the peel of mandarin (Citrus unshiu Marc. Var. Okitsu) cultivated in Cheju Island. Among three different isolation methods investigated, simultaneous distillation gave higher yield 1.14%(w/w) than solvent extraction or cold pressing. The densities of essential oils were between 0.8409 and 0.8530, which showed no significant effect of the isolation methods. Some variations in the number of constituents detected and the content of d-limonene in the peel oils were observed depending upon the isolation methods. The citrus fruit was collected seasonally from the field and used as a sample for analysis. The peel thickness and the peel content of citrus fruit were around 2 mm and about 17% on wet weight basis, respectively, in harvest season. The maximum yield of essential oils was obtained in September from citrus peels just prior to ripeness and thereafter the yield had a tendency of decrease but remained over 1%(w/w). The relative content of d-limonene, the major constituent of citrus peel oils. increased gradually with ripening up to 68.69%(relative peak area, RPA). The other minor constituents were ${\gamma}-terpinene,\;{\beta}-elemene$, farnesene, hexadecanoic acid, ${\alpha}-pinene,\; {\beta}-myrcene$ and linalool in the decreasing order of their own contents of 7.75, 2.96, 2.29, 1.76, 1.63, 1.56 and 1.46%(RPA).

• Science of Emotion and Sensibility
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• v.23 no.1
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• pp.3-16
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• 2020

Recently, as the fashion e-commerce market has expanded, the proportion of online shops that are growing rapidly has increased and with them so too has competition. Most retailers operating online shops need their own competitiveness, and accordingly, the need to develop their logistics service quality components is increasing. This study investigated the quality of the logistics services, which is a factor of the logistics service quality of the internet shop. It influences customer satisfaction and repurchase intention by collecting samples from the customers using online fashion shops. Two hundred customers who shop online were surveyed to extract the data. The sample was subjected to basic statistical analysis using the SPSS 25.0 package, and factor analysis, t-test, ANOVA, and correlation analysis were performed. The results of this study showed that the information quality of proactive return, promptness of the return process, and reliability of the return cost had a positive impact on customer satisfaction, and it had a significant influence on the customer's repurchase intention to the online store. A selection of shops showed high amounts of return reasons, high customer satisfaction, and high repurchase, whereas, in general, many others scored poorly across these criteria. This suggests that a retailer operating online should consider pages for receiving information plus sales content in addition to the quality and constituent factors of its logistics services for returns that influence repurchase and satisfaction.

• Geotechnical Engineering
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• v.14 no.1
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• pp.109-126
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• 1998

The use of fly ash as a contaminant barrier material was studied. Mixing ratio of fly ash to bentonite to meet the requirements for landfill liners was determined. The hydraulic behavior exhibited by the fly ash-bentonite liner and the effects of CaO were investigated through hydraulic conductivity tests under various conditions and microscopic analyses including XRD, SEM, helium porosimetry, and image analysis. The hydraulic conductivity of compacted fly ash decreased with the addition of bentonite, which was due mainly to the expanding of bentonite and partly to the filling of voids by chemical reaction products among constituents of the artificial liner. Because of insufficient CaO content, and rich in content but low-reactive $SiO_2$ contained in the fly ashes used, pozzolanic reaction and resulting effects in the artificial liner were not significant. The reactions among constituting materials and their resulting effects on hydraulic conductivity were controlled not by the apparent amounts of each constituent, but by reaction activities of the materials in the artificial liner.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.36 no.2
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• pp.121-128
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• 2010

We investigated the effects of skin hydration and composition analysis of proteoglycan (chia seed polymer) produced from chia (Salvia hispanica) seed. The result showed that proteoglycan of chia seeds is composed of galactose (46.8 %), glucuronic acid (27.1 %), rhamnose (8.7 %), xylose (7.6 %), glucose (4.9 %), fructose (2.3 %), mannose (1.8 %), arabinose (0.9 %) and the amount of proteins contained is 31.3 mg/g with the constituent amino acid compositions (mg/g) of Asp (1.9), Glu (3.6), Ser (0.9), Gly (3.6), Thr (0.8), Arg (1.0), Ala (2.0), Tyr (0.4), Cys (4.8), Val (1.1), Phe (0.5), Ile (0.6), Leu (0.9). The molecular weight of the proteoglycan measured by GPC (Gel Permeation Chromatography) is the range of 100,000~250,000 Da and the average molecular weight is 170,000 Da. The moisturizing effects and trans-epidermal water loss (TEWL) of chia seed polymer in cosmetic products (O/W emulsion) were studied in vivo. Chia seed polymer showed good skin hydration effects when compared with sodium hyaluronate which is a common moisturizer. Taken all together, chia seed polymer should be a very useful cosmetic ingredient as a moisturizer and a protecting agent from various skin irritations.

• Journal of Korean Society of Forest Science
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• v.109 no.4
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• pp.468-476
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• 2020

we developed a stand density management diagram for Quercus variabilis in order to predict the final cutting ages of coppice forests based on management objectives. The sample data were classified into two groups: 603 data points for analysis and 113 data points for verification. Using these data, a stand density management diagram was constructed and a goodness-of-fit test was performed. The explanatory power (R2) of the constituent models for the stand density management diagram was 0.732 for the equivalent height curve and 0.990 for the equivalent diameter curve. According to the analysis of the final cutting age rangeof the highest production, the final cutting ages for 900 buds remaining per hectare was 42-44 years, and that for the 1,800 buds remaining per hectare was 38-42 years. With the third-grade log set as the production target, the final cutting age range with site index 16 and 14 was 25-28 years and 29-33 years, respectively. The results of this study provide baseline data for establishing a management plan for Q. variabilis coppice stands.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1541-1555
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• 2022

Red tide has potential to harm marine ecology and aquaculture. Research on detecting red tide using various optical remote sensors has been conducted, but most of existing algorithms for detecting red tide has limitations, especially in shallow coastal waters with high levels of suspended sediment. For enhanced understanding of the optical behavior of red tide waters, analysis on remote sensing reflectance and water constituent is becoming increasingly important. This study analyzed the optical remote sensing data and water quality variables(Chl-a_(Spec), SPM, a_ph, a_d, Turbidity, Chl-a_(HPLC), Dominant species) of red tide waters. The data were collected from ship-based campaigns. In addition to the research on detecting red tide, the remote sensing reflectance and extinction coefficients for mesodinium and cochlodinium species were also analyzed. Through the analysis, it was possible to estimate the red tide chlorophyll concentration based on a specific wavelength of the remote sensing reflectance. The study found that chlorophyll concentration and phytoplankton absorption coefficient were highly correlated(R²=0.9), and that the RE_diff formula provided a more accurate estimate of red tide concentration than the B-G ratio.