• Journal of the Korean Applied Science and Technology
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• v.40 no.4
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• pp.856-867
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• 2023

Due to the increase in fine dust caused by environmental pollution, oxidative damage and aging of the skin are accelerated. In this study, the antioxidant, hyaluronic acid, filaggrin, MMP-1, and ROS level of selected herbal extracts were evaluated to confirm the protective efficacy of keratinocytes treated PM10. As a result, the antioxidant capacity of 1,1-diphenyl-2-picrylhydrazyl(DPPH), 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid(ABTS), and FRAP assay increased in a concentration-dependent manner. Keratinocytes the group treated with 300 ㎍/ml of PM10, hyaluronic acid and filaggrin decreased by more than 50%, and increased in the group treated with extracts of Alpinia officinarum, Ulmus macrocarpa, and Ulmus macrocarpa but decreased when the extract was treated, which is evaluated as inhibiting the degradation of collagen and elastin. In addition, in the case of ROS measurement using zebrafish embryos, it was confirmed that the extract was reduced when the extract was treated 25 ㎍/ml, the intensity of fluorescence similar to the negative control was shown, confirming that the production of ROS was significantly reduced. Through this study, the selected oriental medicinal materials, Alpinia officinarum, Ulmus macrocarpa, and Ulmus macrocarpa, protect the skin from fine dust. It is thought that it can be used as an anti-aging product for skin improvement as a material that can be improved or improved.

• Analytical Science and Technology
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• v.28 no.6
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• pp.409-416
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• 2015

ICP-AES has been used in many laboratories due to the advantages of wide calibration range and multi-element analysis, but it may give erroneous results and suffer from spectral interference due to the large number of emission lines associated with each element. In this study, certified reference materials (CRMs) and field samples were analyzed by ICP-AES and HG-AAS according to the official Korean testing method for soil pollution to investigate analytical problems. The applicability of HG-ICP-AES was also tested as an alternative method. HG-AAS showed good accuracies (90.8~106.3%) in all CRMs, while ICP-AES deviated from the desired range in CRMs with low arsenic and high Fe/Al. The accuracy in CRM030 was estimated as below 39% at the wavelength of 193.696 nm by ICP-AES. Significant partial overlaps and sloping background interferences were observed near to 193.696 nm with the presence of 50 mg/L Fe and Al. Most CRMs were quantified with few or no interferences of Fe and Al at 188.980 nm. ICP-AES properly assessed low and high level arsenic for field samples, at 188.980 nm and 193.696 nm, respectively. The importance of the choice of measurement wavelengths corresponding to relative arsenic level should be noted. Because interferences were affected by the sample matrix, operation conditions and instrument figures, the analysts were required to consider spectral interferences and compare the analytical performance of the recommended wavelengths. HG-ICP-AES was evaluated as a suitable alternative method for ICP-AES due to improvement of the detection limit, wide calibration ranges, and reduced spectral interferences by HG.

• Journal of the Korean earth science society
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• v.21 no.5
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• pp.611-622
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• 2000

To investigate the exchange rates of mercury(Hg) across soil-air boundary, we undertook the measurements of Hg flux using gradient technique from a major waste reclamation site, Nan-Ji-Do. Based on these measurement data, we attempted to provide insights into various aspects of Hg exchange in a strongly polluted soil environment. According to our analysis, the study site turned out to be not only a major emission source area but also a major sink area. When these data were compared on hourly basis over a full day scale, large fluxes of emission and deposition centered on daytime periods relative to nighttime periods. However, when comparison of frequency with which emission or deposition occurs was made, there emerged a very contrasting pattern. While emission was dominant during nighttime periods, deposition was most favored during daytime periods. When similar comparison was made as a function of wind direction, it was noticed that there may be a major Hg source at easterly direction to bring out significant deposition of Hg in the study area. To account for the environmental conditions controlling the vertical direction of Hg exchange, we compared environmental conditions for both the whole data group and those observed from the wind direction of strong deposition events. Results of this analysis indicated that the concentrations of pollutant species varied sensitively enough to reflect the environmental conditions for each direction of exchange. When correlation analysis was applied to our data, results indicated that windspeed and ozone concentrations best reflected changes in the magnitudes of emission/deposition fluxes. The results of factor analysis also indicated the possibility that Hg emission of study area is temperature-driven process, while that of deposition is affected by a mixed effects of various factors including temperature, ozone, and non-methane HCs. If the computed emission rate is extrapolated to the whole study area we estimate that annual emission of Hg from the study area can amount to approximately 6kg.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.658-665
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• 2013

In this study, we measured particulate matter(PM) which emerged as the hot issue from the International Maritime Organization(IMO) and the exhaust emission using HANBADA, the training ship of Korea Maritime University. In particular, the PM was obtained with TEM grid. PM structure was observed by electron microscopy. And exhaust gases such as NOx, $CO_2$, and CO were measured using the combustion gas analyzer(PG-250A, HORIBA). The results of this study are as follows. 1) When the ship departed from the port, the maximum difference in PM emissions were up to 30 % due to the Bunker Change. 2) Under the steady navigation, emission of PM was $1.34mg/m^3$ when Bunker-A is changing L.R.F.O(3 %). And, at the fixed L.R.F.O (3 %), emission of PM was $1.19mg/m^3$. When the main engine RPM increased up to 20 % with fixed L.R.F.O(3 %), emission of PM was $1.40mg/m^3$. When we changed to low quality oil(L.R.F.O(3 %)), CO concentration from main engine increased about 16 %. On the other hand, when the main engine RPM is rising up to 20 %, CO concentration is increased more than 152 percent. These results imply that the changes of RPM is a dominant factor in exhaust emission although fuel oil type is an important factor. 3) The diameter of PM obtained with TEM grid is about $4{\sim}10{\mu}m$ and its structure shows porous aggregate.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.769-777
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• 2002

Using four components - nonionic surfactants, water, hydrocarbon oil and an alcohol as cosurfactant, 12 types of cleaning agents were prepared, and their physical properties such as surface tension, viscosity, electroconductivity and phase stability were measured. As the formulated cleaning agents have low surface tensions(30.5-31.1 dyne/cm) and low viscosities (1.6-7.2 c.p.), they are satisfied with the general physical properties of water-in-oil(W/O) microemulsions for their industrial use. They showed a tendency that their temperature range for stable one-phase microemulsion decreased in accordance with the increase of alcohol/surfactant(A/S) ratio in the formulations. However, the temperature range of one-phase microemulsion was much more affected by hydrophilic lipophillic balance(HLB) value of the nonionic surfactant which increased its temperature range and it increased in accordance with the higher HLB value in the formulations. And the maximum content of water which can keep stable one-phase W/O microemulsion was measured at each sample. In addition, their temperature range for stable one-phase microemulsion was also measured. It was confirmed that the selection of surfactant type was very important for formulating a cleaning agent, since the W/O microemulsion system with the nonionic surfactant of the lower HLB value showed better cleaning efficacy that of the higher HLB value for abietic acid as a soil, which was used for preparing a rosin-type flux. In the formulated cleaning agents with the increase of A/S ratio in the formulations, however, there was no significant difference in cleaning efficacy. It was investigated that the differences of their cleaning efficacy was affected by the change of the condition of temperature and sonicating frequency as important factors in the industrial cleaning. That is, the higher, their cleaning temperature and the lower, their sonicating frequency, the more increased, their cleaning efficacy. Furthermore, using optical instruments like UV/Visable Spectrophotometer and FT-IR Spectrometer, their cleaning efficacy for abietic acid was measured. The removal of soil from the contaminated rinse water was measured by gravity separation method in the rinse bath. As a result, the cleaning agent system having the nonionic surfactant of HLB value 6.4 showed over 85% water-oil separation efficacy at over $25^{\circ}C$. Therefore, it was demonstrated in this work that the formulating cleaning agents were very effective for cleaning and economical in the possible introduction of water recycling system.

• Economic and Environmental Geology
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• v.55 no.4
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• pp.407-419
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• 2022

Soil(vadose zone) gas compositions were measured for about 3 days to suggest a method for monitoring and interpreting soil gas data collected around wells from which methane(CH₄) is outflowing. The vadose zone gas samples were collected within 1 m around two test wells(TB2 and TB3) at Pohang and analyzed for CO₂, CH₄, N₂ and O₂ concentrations in situ. CO₂ flux was measured beside TB2. In addition, gas samples from well head in TB2 and atmospheric air samples were collected for comparison. Carbon isotopes of CO₂(δ¹³C_CO2) of samples collected on the last day of the study period were analyzed in the laboratory. The two test wells (TB2 and 3) were 12.7 m apart and only TB3 was cemented to the surface. According to the bio-geochemical process-based interpretation, the relationships between CO₂ and O₂, N₂, and N₂/O₂ of vadose zone gas were plotted between the lines of CH₄ oxidation and CO₂ dissolution. In addition, the CH₄ concentrations of gas samples from the wellhead of the uncemented well (TB2) were 5.2 times higher than the atmospheric CH₄ concentration. High CO₂ concentrations (average 1.148%) of vadose zone gas around TB2 seemed to be attributed to the oxidation of CH₄. On the other hand, the vadose zone CO₂ around the cemented well(TB3) showed a relatively low concentration(0.136%). This difference indicates that the vadose zone gas(including CO₂) around the CH₄ outflowing well were strongly affected by well completion(cementing). This study result can be used to establish strategies for environmental monitoring of soil around natural gas sites, and can be used to monitor leakage around injection and observation wells for CO₂ geological storage. In addition, the method of this study is useful for soil monitoring in natural gas storage and oil-contaminated sites.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.4
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• pp.365-373
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• 2016

Composites are the most useful restorative material. However, composites have some disadvantages such as polymerization shrinkage, long working time, and susceptibility to water and contamination, which are stood out more especially when treating children. To solve these problems, bulk-fill composites have been developed. The aim of this study is to compare mechanical properties of bulk-fill and conventional composites. Bulk-fill composites (SureFil SDR flow (SDR), Tetric N-Ceram bulk fill (TBF)) and conventional composites (Filtek Z-350 (Z-350), Unifil Flow (UF), Unifil Loflo Plus (UL)) were used. The Vickers hardness tester was used to measure the microhardness of materials, and Fourier transform infrared spectroscopy was used to measure the degree of conversion. Polymerization shrinkage was measured by using a linometer. Flexural and compressive properties were measured by using the universal testing machine. Data were statistically analyzed by ANOVA and Scheffe's post hoc test. The level of significance was set to p < 0.05. Most conventional composites showed higher microhardness than bulk-fill composites. However, bulk-fill composites showed a higher top/bottom microhardness ratio than conventional composites. Bulk-fill composites showed a higher top/bottom degree of conversion ratio than conventional composites. The polymerization shrinkage was highest in UL and lowest in Z-350. The polymerization shrinkage of flowable composites was higher than that of non flowable composites. The compressive properties were highest in Z-350 and lowest in SDR and UL. In terms of flexural properties, Z-350 was the highest. However, none of the bulk-fill composites exhibited mechanical properties as good as those of conventional composites. Nonetheless, the ratio of microhardness and degree of conversion, which are important properties of bulk filling, were higher in bulk-fill composites. Therefore, the bulk-fill composites might be considered suitable restorative materials in pediatric dentistry.

• Microbiology and Biotechnology Letters
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• v.41 no.4
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• pp.449-455
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• 2013

Human skin is constantly exposed to environmental conditions such as UV rays, polluted air, and chemical products. UV rays, in particular, affect skin in many ways causing wrinkles, fine wrinkles, rough skin, and xeroderma through a skin aging process. The purpose of this study was to investigate the anti-wrinkling effect of Juniperus rigida Sieb., derived from a common cedar tree found the world over. Measuring the elastase to investigate wrinkling efficacy, it was shown that at a concentration level of $1,000{\mu}g/ml$ of the two extracts, the water extract exhibited a lower than 10% inhibition activity, while the ethanol extract exhibited a 68.5% inhibition activity. Collagenase inhibition activity in the water extract and ethanol extract were 44.9% in the former and 97.2% in the latter extract, which in the case of the ethanol extract, is similar to ascorbic acid (99.6%). Moreover, measuring the biosynthesis of collagen by fibroblast, a concentration level of $50{\mu}g/ml$ of ethanol extract produced 151.52% of biosynthetic promotion, proving that the ethanol extract acts as a superb anti-wrinkling agent. The result of an investigation conducted on the influence of the ethanol extract on MMP-1 caused by UVA showed that at a concentration level of $1,00{\mu}g/ml$ of the ethanol extract of J. rigida Sieb a 67.1% inhibition activity was noted. At a concentration level of $50{\mu}g/ml$ of the ethanol extract of J. rigida Sieb a 35% and 39% inhibition ratio to MMP-1 protein and mRNA were observed respectively, thereby restraining the appearance of the collagen breakdown enzyme MMP-1 and wrinkle creation by skin photo-aging.

• Korean Journal of Remote Sensing
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• v.35 no.6_1
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• pp.919-932
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• 2019

Fine particulate matter (PM2.5) is not only affected by anthropogenic emissions, but also intensifies, migrates, decreases by hydrometeorological factors. Therefore, it is essential to understand relationships between the hydrometeorological factors and PM2.5 concentration. In Korea, PM2.5 concentration is measured at the ground observatories and estimated data are given to locations where observatories are not present. In this way, the data is not suitable to represent an area, hence it is impossible to know accurate concentration at such locations. In addition, it is hard to trace migration, intensification, reduction of PM2.5. In this study, we analyzed the relationships between hydrometeorological factors, acquired from Global Land Data Assimilation System (GLDAS), and PM2.5 by means of Bayesian Model Averaging (BMA). By BMA, we also selected factors that have meaningful relationship with the variation of PM2.5 concentration. 4 PM2.5 concentration models for different seasons were developed using those selected factors, with Aerosol Optical Depth (AOD) from MODerate resolution Imaging Spectroradiometer (MODIS). Finally, we mapped the result of the model, to show spatial distribution of PM2.5. The model correlated well with the observed PM2.5 concentration (R ~0.7; IOA ~0.78; RMSE ~7.66 ㎍/㎥). When the models were compared with the observed PM2.5 concentrations at different locations, the correlation coefficients differed (R: 0.32-0.82), although there were similarities in data distribution. The developed concentration map using the models showed its capability in representing temporal, spatial variation of PM2.5 concentration. The result of this study is expected to be able to facilitate researches that aim to analyze sources and movements of PM2.5, if the study area is extended to East Asia.

• Journal of Bio-Environment Control
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• v.32 no.2
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• pp.106-114
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• 2023

With rising concerns about pesticide spray drift by aerial application, this study attempt to evaluate aerodynamic property and collection efficiency of spray drift according to the leaf area index (LAI) of crop for preventing undesirable pesticide contamination by the spray-drift tunnel experiment. The collection efficiency of the plant with 'Low' LAI was measured at 16.13% at a wind speed of 1 m·s^-1. As the wind speed increased to 2 m·s^-1, the collection efficiency of plant with the same LAI level increased 1.80 times higher to 29.06%. For the 'Medium' level LAI, the collection efficiency was 24.42% and 43.06% at wind speed of 1 m·s^-1 and 2 m·s^-1, respectively. For the 'High' level LAI, it also increased 1.24 times higher as the wind speed increased. The measured results indicated that the collection of spray droplets by leaves were increased with LAI and wind speed. This also implied that dense leaves would have more advantages for preventing the drift of airborne spray droplets. Aerodynamic properties also tended to increase as the LAI increased, and the regression analysis of quadric equation and power law equation showed high explanatory of 0.96-0.99.