• Journal of the Korean Chemical Society
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• v.64 no.6
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• pp.416-428
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• 2020

This study analyzed the uses of external representations presented in the matter units of the 7th-grade science digital textbooks developed under the 2015 revised national curriculum. The level, form, presentation, and interactivity of external representations presented in 5 types of digital textbooks were analyzed. As for the level, the macroscopic level of representations was mainly presented. The macroscopic level and microscopic level of representations were presented together in the particle description. As for the form, visual-verbal and visual-nonverbal representations were usually presented across the board. Very few audial-verbal and audial-nonverbal representations were presented. Visual-verbal and audial-verbal representations were mostly presented in formal form, and visual-nonverbal representations were mostly presented in illustration without movement. The presentation of representations was analyzed in three aspects. First, visual-verbal and visual-nonverbal representations were mainly presented together and none of audial-verbal and visual-nonverbal representations were presented together. When the representations of the audial-verbal, visual-nonverbal, and visual-verbal were presented together, some of the information presented in audial-verbal representations was repeatedly presented in the visual-verbal representations. Second, audial-nonverbal representations not related to learning content were presented along with other representations. Third, there were few cases of arranging visual-verbal and visual-nonverbal representations on the next pages. Audialverbal and visual-nonverbal representations were always presented synchronized. As for the interactivity, the manipulation level was mainly presented in the main area, and the feedback level was mainly presented in the activity area. The adaptation level and the communication level of interactivity were presented very few. Based on the results, the implications for the direction of constructing digital textbooks were discussed.

• Korean Journal of Remote Sensing
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• v.37 no.3
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• pp.543-557
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• 2021

Because aerosols have different spectral characteristics according to the size and composition of the particle and to the satellite sensors, a comparative analysis of aerosol products from various satellite sensors is required. In South Korea, however, a comprehensive study for the comparison of various official satellite AOD (Aerosol Optical Depth) products for a long period is not easily found. In this paper, we aimed to assess the performance of the AOD products from MODIS (Moderate Resolution Imaging Spectroradiometer), VIIRS (Visible Infrared Imaging Radiometer Suite), Himawari-8, and Sentinel-3 by referring to the AERONET (Aerosol Robotic Network) sun photometer observations for the period between January 2015 and December 2019. Seasonal and geographical characteristics of the accuracy of satellite AOD were also analyzed. The MODIS products, which were accumulated for a long time and optimized by the new MAIAC (Multiangle Implementation of Atmospheric Correction) algorithm, showed the best accuracy (CC=0.836) and were followed by the products from VIIRS and Himawari-8. On the other hand, Sentinel-3 AOD did not appear to have a good quality because it was recently launched and not sufficiently optimized yet, according to ESA (European Space Agency). The AOD of MODIS, VIIRS, and Himawari-8 did not show a significant difference in accuracy according to season and to urban vs. non-urban regions, but the mixed pixel problem was partly found in a few coastal regions. Because AOD is an essential component for atmospheric correction, the result of this study can be a reference to the future work for the atmospheric correction for the Korean CAS (Compact Advanced Satellite) series.

• Journal of the Korean GEO-environmental Society
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• v.22 no.6
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• pp.17-26
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• 2021

Ground investigation and result analysis generally used to examine all sorts of structures' subsidence or stability can be classified into sandy soil and cohesive soil, and analysis on the liquid limit of soil is utilized to evaluate the physical properties of ground and types or technical behavior of soil. The most widely used method to analyze liquid limit is Casagrande with which liquid limit can be calculated relatively easily; however, it is fairly difficult to apply it to soil equipped with intermediate properties. Therefore, concerning the properties of soil having the intermediate properties of sedimentary ground, this researcher mixed the clay from Yangsan, Gwangyang, and Busan with sandy soil to make intermediate soil and then carried out the test of consistency limit and also evaluated applicability by using the suggested formula of consistency revision. The sample of intermediate soil was the mixture of clay and sandy soil, and to produce intermediate soil, the content (F_c) of fine soil was applied as 50%, 75%, or 100%. Regarding the physical properties of intermediate soil, to maintain the properties of clay in the natural state, bentonite was added at a fixed rate for controlling the properties of clay, and then, consistency was analyzed. By adopting the formula of consistency revision suggested in advanced research, this author analyzed consistency based on the experiment and consistency based on the suggested formula of revision. Also, about intermediate soil collected at the site, consistency based on the experiment and consistency based on the suggested formula of revision were analyzed comparatively, and about intermediate soil collected, this researcher analyzed particle size and calculated the content (F_c) of fine soil to analyze intermediate soil in diverse conditions. Moreover, about intermediate soil collected at the site, the suggested formula of consistency revision was applied to calculate the compression index, and the compression index based on the experiment and the compression index based on the suggested formula were analyzed comparatively to evaluate the applicability of the suggested formula.

• Composites Research
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• v.34 no.3
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• pp.192-198
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• 2021

Due to enormous market growing of electric vehicles without combustion engine, reducing unwanted BSR (buzz, squeak, and rattle) noise is highly demanded for vehicle quality and performance. Particularly, innerbelt weatherstrips which not only block wind noise, rain, and dust from outside, but also reduce noise and vibration of door glass and vehicle are required to exhibit high damping properties for improved BSR performance of the vehicle. Thermoplastic elastomers (TPEs), which can be recycled and have lighter weight than thermoset elastomers, are receiving much attention for weatherstrip material, but TPEs exhibit low material damping and compression set causing frictional noise and vibration between the door glass and the weatherstrip. In this study, high damping EPDM (ethylene-propylene-diene monomer)/PP (polypropylene) thermoplastic vulcanizates (TPV) were investigated by varying EPDM/PP ratio and ENB (ethylidene norbornene) fraction in EPDM. Viscoelastic properties of TPV materials were characterized by assuming that the material damping is directly related to the viscoelasticity. The optimum material damping factor (tanδ peak 0.611) was achieved with low PP ratio (14 wt%) and high ENB fraction (8.9 wt%), which was increased by 140% compared to the reference (tanδ 0.254). The improved damping is believed due to high fraction of flexible EPDM chains and higher interfacial slippage area of EPDM particles generated by increasing ENB fraction in EPDM. The stick-slip test was conducted to characterize frictional noise and vibration of the TPV weatherstrip. With improved TPV material damping, the acceleration peak of frictional vibration decreased by about 57.9%. This finding can not only improve BSR performance of electric vehicles by designing material damping of weatherstrips but also contribute to various structural applications such as urban air mobility or aircrafts, which require lightweight and high damping properties.

• Journal of Korean Society of Forest Science
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• v.110 no.2
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• pp.129-140
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• 2021

The study investigates the correlation between the seasonal changes in the absorption of fine dusts and the fine structure of surface on each type of street tree, such as Quercus myrsinifolia, Quercus glauca, Quercus salicina, Camellia japonica, and Prunus × yedoensis in the southernareas of Korea. The absorption ranges of fine dust were 31.51~110.44 ㎍/cm² in January, 23.20~79.30 ㎍/cm² in November, 22.68~76.90 ㎍/cm² in May, and 9.88~49.91 ㎍/cm² in August. The absorption value was about 54.4% higher in January than in May. With the grooves and hairs on the leaf surface and lots of wax, Q. salicina seems related to the high absorption rate of fine dust for each fine dust particle size. The one with gloss and smooth leaf surface has a low amount of wax. C. japonica Prunus × yedoensisshowed a low absorption rate of fine dust in each season. Whereas the increase in porosity density, length, and leaf area size can be related to the reduced PM and increasedabsorption rate, the leaf surface roughness, total wax amount, and porosity width can be related to the increase in the PM absorption rate. There was also a high correlation between the total wax amount and absorption rate of the leaf surface at the size of PM_0.2 than PM₁₀ and PM_2.5. These results imply that the quantitative and qualitative trais of leaf, such as wax amounts and leaf surface,can increase the absorption of fine dusts, and the small-sized particles seem to be highly adsorbed with the high wax amounts.

• Economic and Environmental Geology
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• v.54 no.6
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• pp.717-731
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• 2021

We analyzed the characteristics of the habitat environment for the Seonam study area in Ulsan, the southern shore of the East Sea using bathymetry and seafloor environment data. The depth of the study area ranges from about 0 m to 23 m. In the west of the study area, the water depth is shallow with a gentle slope, and the water depth becomes deeper with a steep slope in the east. Due to the right-lateral strike-slip faults located in the continental margin of the East Sea, the fracture surfaces of the seabed rocks are mainly in the N-S direction, which is similar to the direction of the strike faults. Three seafloor types (conglomeratic-grained sandy, coasre-graiend sandy, fine-grained sandy) and rocky bottom area have been classified according to the analyses of the bathymerty, seafloor image, and surface sediment data. The rocky bottom areas are mainly distributed around Seaoam and in the northern and southern coastal area. But the intermediate zone between Seonam and coastal area has no rocky bottom. This intermediate area is expected to have active sedimentation as seawater way. The sandy sediments are widely distributed throughout the study area. Underwater images and UAV images show that Cnidarians, Brachiopods, Mollusks are mostly dominant in the shallow habitat and various Nacellidae, Mytilidae live on the intertidal zone around Seonam. Annelida and Arthropod are dominant in the sandy sediments. The distribution of marine organism in the study area might be greatly influenced by the seafloor type, the composition and particle size distribution of the seafloor sediments. The analysis of habitat environment mapping with bathymetry, seafloor data and underwater images is supposed to contribute to the study of the structure and function of marine ecosystem.

• Journal of Food Hygiene and Safety
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• v.37 no.5
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• pp.339-346
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• 2022

This study was performed to investigate the quality characteristics and antioxidant activity of black soybean Sunsik product with functional food ingredients and functional labeling system. We prepared black soybean Sunsik (BS) containing black beans, cereals, and vegetables. Black soybean Sunsik with nondigestible maltodextrin and calcium lactate (BSN) was prepared by adding non-digestible maltodextrin and calcium lactate to the base recipe to apply a functional labeling system. The particle size in BS was 118.00 ㎛, whereas BSN was 127.00 ㎛. The respective L, a, and b color values of BS were 73.25, 2.36, and 14.21. The respective L, a, and b values of BSN were 73.21, 2.36, and 14.31. The respective water retention capacities of BS and BSN were 241.67% and 216.33%. No significant difference was observed between BS and BSN in the three physicochemical properties described above. However, the pH of BSN was 5.45, which was significantly lower than that of BS. The total respective phenolic contents of BS and BSN were 1.75 mg GAE/g and 1.61 mg GAE/g, and total respective flavonoid contents of BS and BSN were 6.36 mg RE/g and 5.95 mg RE/g. The antioxidant capacities of BS and BSN were compared via assays of DPPH and ABTS radical scavenging activities, FRAP, and reducing power. The antioxidant activities of BS and BSN increased in a dose-dependant manner. No significant difference between BS and BSN was observed in any measure of antioxidant capacity. These results suggested that the addition of functional food ingredients (non-digestible maltodextrin and calcium lactate) did not affect the quality characteristics and antioxidant activity of black soybean Sunsik.

• Economic and Environmental Geology
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• v.55 no.1
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• pp.97-109
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• 2022

This study focused on the physicochemical effects of bottom ash dissolved precipitation on the soil and groundwater environment. The iced column and percolation experiments showed that most of the bottom ash particles were drained as the ash-dissolved solution, while the charcoal powder was filtered through the soil. Ion species of Al, As, Cu, Cd, Cr, Pb, Fe, Mn, Ca, K, Si, F, NO₃, SO₄ were analyzed from the eluates collected during the 24 h column test. In the charcoal powder eluates, a high concentration of K was detected at the beginning of the reaction, but it decreased with time. The concentrations of Al and Ca were observed to increase with time, although they existed in trace amount. In the bottom ash eluates, the concentrations of Ca and SO₄ decreased by 30 mg·L^-1 and 67 mg·L^-1, respectively, over 24 h. It is regarded that the infiltration patterns of the bottom ash and biochar in the unsaturated zone were different owing to their particle sizes and solvent properties. It is expected that a significant amount of the bottom ash will mix with the precipitation and percolate below the water table, especially in the case of thin and highly permeable unsaturated zone. The biochar was filtered through the unsaturated zone. The biochar did not dissolve in the groundwater, although it reached the saturation zone. For these reasons, it is considered that the direct contamination by the bottom ash and biochar are unlikely to occur.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.48 no.1
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• pp.1-10
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• 2022

Customized cosmetics are continuously mentioned as a trend in the cosmetics industry to respond to the recent rapid changes in the social environment and pursue individuality and diversity. Accordingly, four types of liposome essence corresponding to skin types were prepared by varying the ratio of liposome formulation and essence formulation as a customized cosmetic base that can be easily mixed and applied at the workplace. The volatilization residues of four types of liposome essence were measured and the nanoparticle size, polydispersity index, zeta potential and viscosity according to time for 90 d were measured, and Turbiscan was measured as a method for evaluating the stability of a colloidal dispersion system. In addition, a simple usability evaluation was performed for four types of liposome essence corresponding to the skin type. As a result, the amount of volatile residue in the four types of liposome essence was increased in dry products rather than oily ones, and the particle size showed a tendency to increase with time in the range of 165 to 175 nm, increasing up to 31.5%, and the polydispersity index was 0.23 to 0.26. There was little change with time, and the zeta potential was -74 to -72 mV, showing a slight decrease with time, but there was little change to the extent of a maximum decrease of 14.0%. Viscosity showed a decreasing trend with time in the range of 2,580 ~ 3,290 cps, showing a maximum decrease of 17.5%. In the turbiscan measurement, all of the turbiscan stability index, a measure of stability, were less than 1.0, indicating dispersion stability. In the overall simple usability satisfaction evaluation for skin types (6 points), products for oily skin (5.33 ± 0.75 points) > products for medium dry skin (5.13 ± 0.95 points) > products for dry skin (5.03 ± 0.96 points) > products for oily skin (4.80 ± 1.04 points) points) were evaluated in order. The four types of liposome essence corresponding to skin types with different ratios of liposome formulation and essence formulation were physically stable, and the possibility of application as a customized cosmetic base according to skin type was confirmed.

• Economic and Environmental Geology
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• v.55 no.1
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• pp.63-76
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• 2022

Dacitic tuffs, 97 to 118 m thick, were recovered from the lower part of the subsurface Seongdongri Formation, Janggi Basin, which was drilled to assess the potential for underground storage of carbon dioxide. The tuffs are divided into four depositional units(Unit 1 to 4) based on internal structures and particle componentry. Unit 1 and Units 3/4 are ignimbrites that accumulated in subaerial and subaqueous settings, respectively, whereas Unit 2 is braided-stream deposits that accumulated during a volcanic quiescence, and no dacitic tuff is observed. A series of analysis shows that mordenite and clinoptilolite mainly fill the vesicles of glass shards, suggesting their formation by replacement and dissolution of volcanic glass and precipitation from interstitial water during burial and diagenesis. Glass-replaced clinoptilolite has higher Si/Al ratios and Na contents than the vesicle-filling clinoptilolite in Units 3. However, the composition of clinoptilolite becomes identical in Unit 4, irrespective of the occurrence and location. This suggests that the Si/Al ratio and pH in the interstitial water increased with time because of the replacement and leaching of volcanic glass, and that the composition of interstitial water was different between the eastern and western parts of the basin during the formation of the clinoptilolite in Units 1 and 3. It is also inferred that the formation of the two zeolite minerals was sequential according to the depositional units, i.e., the clinoptilolite formed after the growth of mordenite. To summarize, during a volcanic quiescence after the deposition of Unit 1, pH was higher in the western part of the basin because of eastward tilting of the basin floor, and the zeolite ceased to grow because of the closure of the pore space as a result of the growth of smectite. On the other hand, clinoptilolite could grow in the eastern part of the basin in an open system affected by groundwater, where braided stream was developed. Afterwards, Units 3 and 4 were submerged under water because of the basin subsidence, and the alkali content of the interstitial water increased gradually, eventually becoming identical in the eastern and western parts of the basin. This study thus shows that volcanic deposits of similar composition can have variable distribution of zeolite mineral depending on the drainage and depositional environment of basins.