• Journal of Preventive Medicine and Public Health
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• v.32 no.2
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• pp.191-199
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• 1999

Objectives: To examine the relationship between air pollution exposure and mortality in Seoul for the years of 1991-1995, Methods: Daily counts of death were analyzed by general additive Poisson model, with adjustment for effects of secular trend, seasonal factor, day of the week, heat wave, temperature, and humidity. Pollution variables were ozone, nitrogen dioxide, total suspended particles(TSP), and sulfur dioxide. Results: Daily death counts were associated with ozone(1 day before), nitrogen dioxide(1 day before), TSP(2 days before), sulfur dioxide(2 days before). The association with ozone was most statisfically significant and independent of other air pollutants. Increase of 100 ppb in ozone was associated with 0%(95% Cl= 2%-10%) increase in the daily number of death, This effect was greater in persons aged 65 and older. The relative risks of death from respiratory disease and cardiovascular disease were greater than for all-cause mortality in each pollutant. After ozone level exceeds 25 ppb, the dose-response relationship between mortality and ozone was almost linear. However, the effect of TSP, sulfur dioxide, and nitrogen dioxide on mortality might be confounded with each other. Conclusion: Daily variations in air pollution within the range currently occurring in Seoul might have an adverse effect on daily mortality.

• Analytical Science and Technology
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• v.7 no.3
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• pp.361-369
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• 1994

Voltammetric behavior of some light lanthanide ions($La^{3+}$, $Pr^{3+}$, $Nd^{3+}$, $Sm^{3+}$ and $Eu^{3+}$) in acetonitrile(AN) and dimethylformamide(DMF) has been investigated by direct current, differential pulse polarography and cyclic voltammetry. The reduction of $La^{3+}$, $Pr^{3+}$ and $Nd^{3+}$ in 0.1M TEAP proceeded directly to the metallic state through three-electron charge transfer of irreversible process where as $Sm^{3+}$ and $Eu^{3+}$ proceeded by charge transfer of two steps. As the results of the cyclic voltammetric investigation, the first step reduction of $Sm^{3+}$ and $Eu^{3+}$ were a quasireversible reaction, the second step reductions were an irreversible reaction. The cathodic peak currents of the differential pulse polarogram showed adsorptive properties at lower sweep rates and high concentrations of these metal ions. The peak potenital was shifted to a negative petential and the peak current decreased with the increase of percentage of water in AN. On the other hand, the peak potential was shifted to a positive potential and the peak current decreased with an increased percentage of water in DMF.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.3
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• pp.230-237
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• 2007

Titania nanotube(TiNT) and CdS sol were synthesized by hydrothermal reaction under strongly basic condition and by precipitation reaction of $Cd(N0_3)_2$ and $Na_2S$ aqueous solutions, respectively. After preparing a series of CdS-TiNT composite films on $F:SnO_2$ conducting glass with variation of the mole ratio (r) of TiNT/(CdS+TiNT), their visible light absorption, photocatalytic activities for hydrogen production, and the photocurrent generation were examined. In general, this CdS-TiNT series showed lower photocatalytic activities and photocurrent generation under Xe light irradiation compared to their counterparts, i.e., CdS-$TiO_2$ particulate series. It appeared that TiNTs are not so effective photocatalyic material in spite of their larger specific surface areas compared to $TiO_2$ nanoparticles, because they indicate a poor crystallinity and less intimate interaction or contact with CdS particles owing to the tubular morphology and an easy agglomeration among themselves.

• Economic and Environmental Geology
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• v.39 no.5 s.180
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• pp.567-581
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• 2006

The Au-Ag lode deposits in South Korea are closely associated with the Mesozoic granitoids. Namely, the Jurassic deposits formed in mesozonal environments related to deep-seated granitoids, whereas the Cretaceous ones were developed in porphyry-related environments related to subvolcanic granitoids. The time-space relationships of the Au-Ag lode deposits in South Korea are closely related to the changing plate motions during the Mesozoic. Most of the Jurassic auriferous deposits (about $165{\sim}145$ Ma) show fluid characteristics typical of an orogenic-type gold deposits, and were probably generated in a compressional to transpressional regime caused by an orthogonal to oblique convergence of the Izanagi Plate into the East Asian continental margin. On the other hand, strike-slip faults and caldera-related fractures together with subvolcanic activity are associated with major strike-slip faults reactivated by a northward (oblique) to northwestward (orthogonal) convergence, and probably have played an important role in the formation of the Cretaceous Au-Ag lode deposits (about $110{\sim}45$ Ma) under a continental arc setting. The temporal and spatial distinctions between the two typical Mesozoic deposit styles in South Korea probably reflect a different thermal episodes (i.e., late orogenic and post-orogenic) and ore-forming fluids related to different depths of emplacement of magma due to regional changes in tectonic environment.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.3
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• pp.645-661
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• 2009

The water extract of Dohongsamul-Tang(DHSMT) has been traditionally used to stroke and brain injuries in Oriental Medicine. The present study was designed to investigate the effects of DHSMT on the gene expression profile of cerebral infarction by cDNA microarray in photothrombotic ischemia mouse model. Photothrombotic ischemia was induced in stereotactically held male BALB/c mice using rose bengal and cold light. MRI was performed 24 hours after inducing photothrombosis using 1.5 T MRI and 47 mm surface coil to obtain T2-weighted, and contrast-enhanced images. After MRI test, animal was sacrificed and the brain sections were stained for hematoxylin and eosin and immunohistochemistry. MRI and histological analysis revealed that lesion of thrombotic ischemia was well induced in the cortex with the evidence of biological courses of infarction. The target area of thrombotic infarction was 1 mm anterior to bregma and 3 mm lateral to midline with 2 mm in diameter, which were decreased by administration of DHSMT. To assess gene expression pattern of cerebral infarction, mRNA was isolated and reacted with microarray chip(Agilant's DNA Microarray 44K). Scatter and MA plot analysis were performed to clustering of each functional genes. M value [M=log2(R/G), A={log2(R ${\times}$ G)}/2] was between -0.5 and +0.5 with 40% difference. After pretreatment with DHSMT, the expression levels of mRNA of many genes involved in various signaling pathway such as apoptosis, cell cycle, cell proliferation, response to oxidative stress, immune response, angiogenesis, and inflammatory cytokine were markedly inhibited in photothrombotic ischemia lesion compared to the control group. These results suggest that DHSMT prevent ischemic death of brain on photothrombotic ischemia model of mice through modulation of gene expression at the transcriptional level.

• Applied Chemistry for Engineering
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• v.2 no.2
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• pp.175-184
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• 1991

Ultraviolet curable coatings are often used to protect the surface of polymer materials exposed to the ultraviolet radiation. However, the adhesion of epoxy acrylate on poly(vinyl chloride) and the UV curable coating on polystyren are poor. The objective of this work was to improve the adhesion of coating according to various formulations of the reactive diluents and finishing methods using the photografting of multifunctional acrylate and the surface activation on polymer surface impregnated a phtoinitiator. The addition of Tripropylene glycole diacrlate in the formulation of coating results in the improvement of adhesion of coating due to the flexibility. But the increase of the crosslinking density which results from the oxidation of surface during the exposure of UV radiation caused the loss of adhesion of coating exept the photografting method. In the trimethylolpropane triacrylate the improvement of adhesion are considerable due to the chemical bond between multifundtional acrylate and surface. From this work we expect to achieve the varity and functionality in the formulation of coating according to the photografting and surface activating of polymer.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.4
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• pp.261-268
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• 2019

Climate change and drought stress are having profound impacts on crop growth and development by altering crop physiological processes including photosynthetic activity. But finding a rapid, efficient, and non-destructive method for estimating environmental stress responses in the leaf and canopy is still a difficult issue for remote sensing research. We compared the relationships between photochemical reflectance index(PRI) and various optical and experimental indices on soybean drought stress under climate change conditions. Canopy photosynthesis trait, biomass change, chlorophyll fluorescence(Fv/Fm), stomatal conductance showed significant correlations with midday PRI value across the drought stress period under various climate conditions. In high temperature treatment, PRI were more sensitive to enhanced drought stress, demonstrating the negative effect of the high temperature on the drought stress. But high CO₂ concentration alleviated the midday depression of both photosynthesis and PRI. Although air temperature and CO₂ concentration could affect PRI interpretation and assessment of canopy radiation use efficiency(RUE), PRI was significantly correlated with canopy RUE both under climate change and drought stress conditions, indicating the applicability of PRI for tracking the drought stress responses in soybean. However, it is necessary to develop an integrated model for stress diagnosis using PRI at canopy level by minimizing the influence of physical and physiological factors on PRI and incorporating the effects of other vegetation indices.

• Clean Technology
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• v.12 no.4
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• pp.244-249
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• 2006

The photocatalytic degradation of trichloroethlylene (TCE), has been investigated over $TiO_2$ photocatalysts irradiated with solar light. The effect of operational parameters, i.e., initial TCE concentration, $TiO_2$ concentration, pH and additives ($H_2O_2$, persulphate($S_2O{_8}^-$)) on the degradation rate of aqueous solution of TCE has been examined. The results presented in this work demonstrated that degradation of the TCE with $TiO_2/solar$ light was enhanced by augumentation in $TiO_2$ loading, pH, and adding additives but was inhibited by increase in initial TCE concentration. Also individual use of $H_2O_2$ was far more effective than using persulphate in TCE removal efficiency. Furthermore, the relative toxicity with a $solar/TiO_2/H_2O_2$ system was about 15% lower than with a $solar/TiO_2/persulphate$ system and about 35% lower than with a $solar/TiO_2$ system within a reaction time of 150 min, respectively.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.397-413
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• 2008

In Gaya area, the Boseong kaolin deposits exhibit locally unusual occurrences such as downward enrichment of kaoin minerals, characteristic hydrothermal alterations (illite and stilbite), and phase relations among kaolin minerals in addition to the extensive weathering of anorthositic country rocks. This indicates that the kaolin deposits seem to be genetically formed as a mixed hydrothermal and residual model. The kaolin ores can be divided into five types on the basis of differences in occurrence, mineral composition and characters. These consist of two types of high-grade ores ranging above 80% in grade and low-grade ores as low as less than 80% including feldspar residuals or the peculiar impurity phase of illite-vermiculite-stilbite. Halloysite and kaolinite are mostly coexisted in the Boseong kaolin, and these kaolin minerals exhibit diverse appearances in crystallinity and morphology. Such a diversity in mineral phase and crystallinity seems to be originated from the complexity in genesis. In addition to these diverse characters of the kaolin, its applied-mineralogical characteristics such as chemical composition, thermal properties, whiteness, viscosity, and etc. made it disadvantageous in terms of ore quality.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.2
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• pp.209-218
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• 2010

The fifty six components of volatile organic compounds(VOCs) were continuously measured by the hour to see the distributions their of its concentration and the ozone creating contribution of nitric oxides and VOCs in Gamjeon Odor and VOCs Monitoring Network from April to September, 2008. Aromatics occupied 51.3% of VOCs and paraffins, alkanes and olefins came in order. The monthly concentration of VOCs in Gamjeon was high in July and low in September. As for hourly concentration of ozone and nitric oxides, ozone started to increase since 10am having the highest in the daytime, and nitric oxides had the different trend from that of ozone, showing the lowest in the daytime. The photochemical ozone creating potentials(POCPs) of toluene, propane, m/p-xylene, ethylbenzene, and 1,2,4-trimethylbenzene were 30.6%, 10.2%, 9.4%, 7.4% and 5.2% respectively. These five components occupied 62.8% of total POCPs, which means they contributed to the ozone creation mainly. Related with the ozone creating contribution, the ratio of VOCs to NOx was generally under 6 occupied 72.0%, which came under the area coexisting the limit of VOCs. Therefore it is thought that the management of emission source of VOCs is very important for the reduction of ozone.