• Journal of Ecology and Environment
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• v.38 no.2
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• pp.195-211
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• 2015

The objectives of this research were to determine mean and maximum tolerance ranges of Carassius auratus ($C_a$) and Cyprinus carpio ($C_c$) populations on various physico-chemical parameters and ecological indicator metrics. Little is known about chemical tolerance ranges of the two species, even though these species are widely distributed species in aquatic ecosystems. Maximum tolerance ranges of $C_a$-population to total nitrogen (TN) and total phosphorus (TP) were $20.3mgL^{-1}$ and $2.0mgL^{-1}$, respectively. Optimal ranges of TN and TP in the $C_a$-population were $1.7-5.0mgL^{-1}$ and $0.06-0.30mgL^{-1}$, respectively. Such nutrient regimes of the $C_a$-population were evaluated as hypereutrophy, indicating high tolerance limits. The $C_c$-population had similar ecological characteristics to $C_a$-population, but the mean tolerance ranges of TN, TP, BOD, and COD were significantly (p < 0.05) greater than the $C_a$-population. Ecological patterns of trophic composition and tolerance guilds in the $C_a$-population were similar to those of the $C_c$-population. The model value of Index of Biological Integrity (IBI) of the habitat where C. auratus and C. carpio co-occurred averaged $15.0{\pm}4.3$ and $12.9{\pm}3.6$, respectively. Based on the modified criteria of the United States Environmental Protection Agency (Klemm et al. 1993), it indicated poor ecological health of both species. These results suggest that both species are highly tolerant to chemical and physical habitat conditions of waterbodies, and that the chemical tolerance range of $C_c$-population was higher than $C_a$-population.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.1
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• pp.13-22
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• 1999

This study is carried out to investigate the chemical composition of atmospheric deposition in Cheju Island, Korea. For this purpose, dustfall matter samples are collected by dust jar from August, 1995 to July, 1996 at five sampling sites and total suspended particulate matters (TSP) and rain are also collected at one site from October, 1995 to July, 1996. All the samples collected are analyzed, and then the information of the 19 chemical species and deposition amount of each species is obtained. These data are used to determine the regional trends in dustfall chemistry and deposition, and compare the characteristics of chemical compositions between dustfall, TSP and rainwater.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1573-1578
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• 2009

A computational study of the reactions between Zn-containing species, the products of the thermal decomposition of diethylzinc (DEZn) and water was investigated. The Zn-containing species – $C_2H_5)_2,\;HZnC_2H_5,\;and\;(ZnC_2H_5)_2$ – were assumed to react with water during ZnO metal organic chemical vapor deposition (MOCVD). Density functional theory (DFT) calculations at the level of B3LYP/6-311G(d) were employed for the geometry optimization and thermodynamic property evaluation. As a result dihydroxozinc, $Zn(OH)_2$, was the most probable reaction product common for all three Zn-containing species. A further clustering of $Zn(OH)_2$ was investigated to understand the initial stage of ZnO film deposition. In experiments, the reactions of DEZn and water were examined by in-situ Raman scattering in a specially designed MOCVD reactor. Although direct evidence of $Zn(OH)_2$ was not observed, some relevant reaction intermediates were successfully detected to support the validity of the gas phase reaction pathways proposed in the computational study.

• Journal of Environmental Impact Assessment
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• v.21 no.5
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• pp.631-648
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• 2012

The integrative ecological approaches of chemical assessments, physical habitat modelling, and multi-metric biological health modelling were applied to Gwanpyeong Stream within Gap-Stream watersheds to evaluate environmental impacts on the constructions of residential and commercial complex. For the analysis, the surveys conducted from 45 sites of reference streams within the Gap-Stream watershed and 3 regular sites during 2009 - 2010. Physical habitat health, based on the habitat model of Qualitative Habitat Evaluation Index(QHEI) declined from the headwaters(good - fair condition) to the downstream(poor condition). Chemical water quality, based turbidity and electric conductivity(EC), was degraded toward to the downstream, and especially showed abrupt increases, compared to the values of control streams(CS). Also, concentrations of chlorophyll-a in the downstreams were greater compared to the control stream(CS), indicating an eutrophication. Biological health conditions, based on the Index of Biological Integrity(IBI) using fish assemblages, averaged 19.3 which is judged as a fair condition by the biological criteria of the Ministry of Environment, Korea. The comparisons of model metric values in sensitive species and riffle-benthic species on the Maximum Species Richness Line(MSRL) of 45 reference streams indicated a massive disturbances in all sampling locations. Also, tolerance guild and trophic guild analyses suggest that dominances of tolerant species and omnivores were evident, indicating a biological degradation by habitat disturbances and organic matter pollutions. There was no distinct longitudinal variations of IBI model values from the headwater to the downstream in spite of slight chemical and habitat health gradients among the sampling sites. Overall, integrative ecological health(IEH) scores, based on the chemical, physical, and biological parameters, were low compared to the 45 reference streams due to physical and chemical disturbances of massive constructions of the residential and commercial complex. This stream, thus showed a tendency of typical urban streams which are disturbed in the chemical water quality, habitat structures, and biological integrity. Effective stream management plans and restoration strategies are required in this urban stream for improving integrative stream health.

• Bulletin of the Korean Chemical Society
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• v.26 no.3
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• pp.440-446
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• 2005

A method is described for the determination of dibutyltin (DBT) in sediment by isotope dilution using liquid chromatography inductively-coupled plasma/mass spectrometry (LC-ICP/MS). To achieve the highest accuracy and precision, special attentions are paid in optimization and evaluation of overall processes of the analysis including extraction of analytes, characterization of the standards used for calibration and LC-ICP/MS conditions. An approach for characterization of natural abundance DBT standard has been developed by combining inductively-coupled plasma/optical emission spectrometry (ICP/OES) and LC-ICP/MS for the total Sn assay and the analysis of Sn species present as impurities, respectively. An excellent LC condition for separation of organotin species was found, which is suitable for simultaneous DBT and tributyltin (TBT) analysis as well as impurity analysis of DBT standards. Microwave extraction condition was also optimized for high efficiency while preventing species transformation. The present method determines the amount contents of DBT in sediments with expanded uncertainty of less than 5% and its result shows high degree of equivalence with reference values of an international inter-comparison and a certified reference material (CRM) within stated uncertainties.

• Animal cells and systems
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• v.9 no.1
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• pp.9-11
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• 2005

A new species of the genus Smenospongia (Dictyoceratida, Thorectidae), S. coreana n. sp., is described from Gageodo Island, Korea. This new species is readily distinguished from the other species of Smenospongia by the un-lobated growth forms and un-crowded primary fibres. S. aurea and S. lamellata are no distinction between primary and secondary elements, but this species is easily distinguished from them. The matrix easily derived from the fibres. This species has five sesterterpenes, three scalaranetypes and two linear furanosesterterpenes, in chemical compounds.

• Journal of the Korea Furniture Society
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• v.13 no.2
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• pp.19-28
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• 2002

This study was carried out to investigate the wood properties for efficient utilization of warm temperate tree species. The tested species were Actinodaphne lancifolia Meisn. grown in Korea. Fundamental wood properties such as anatomical, physical and mechanical properties and chemical components were examined. This species was diffuse porous, straight grained and fine textured wood. The heartwoods of this species was not distinguished clearly to the sapwoods. This species had moderate specific gravity, shrinkage, and mechanical properties. And this species had high content of the extractives by organic solvent.

• Bulletin of the Korean Chemical Society
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• v.23 no.1
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• pp.151-153
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• 2002

• The Korean Journal of Ecology
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• v.27 no.5
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• pp.307-310
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• 2004

It was found that seed germination and seedling growth of selected species were inhibited by phytotoxic substance released from fir trees. The aqueous extracts of leaves caused significant inhibition in the seed germination of the receptor plants, Whereas seed germination of some species was not inhibited in extracts of leaves, but seedling elongation of the receptor plants was also decreased by the aqueous extract. Dry weight growth was slightly increased in lower concentration of the extract, while that was proportionally inhibited by higher concentration of the extracts. Chemical substances of fir trees were shown the biological toxicity. The GC method was employed for analysis of phytotoxic chemicals and sixteen chemical substances were identified such as benzoic, phenylacetic, etc. Also 33 volatile substances were identified from the fir tree. These chemical compounds are assumed the substances related to allelopathic potential of Abies holophylla plant species.

• Journal of the Korean Society of Combustion
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• v.13 no.1
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• pp.17-22
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• 2008

A partly implicit/quasi-explicit method is introduced for the solution of detailed chemical kinetics with stiff source terms based on the standard fourth-order Runge-Kutta scheme. Present method solves implicitly only the stiff reaction rate equations, whereas the others explicitly. The stiff equations are selected based on the survey of the chemical Jaconian matrix and its Eigenvalues. As an application of the present method constant pressure combustion was analyzed by a detailed mechanism of hydrogen-air combustion with NOx chemistry. The sensitivity analysis reveals that only the 4 species in NOx chemistry has strong stiffness and should be solved implicitly among the 13 species. The implicit solution of the 4 species successfully predicts the entire process with same accuracy and efficiency at half the price.