• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.730-743
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• 1997

Community structure and distribution patterns of benthic polychaetes were studied in Aug. 1983 and Feb. 1984 in Kwangyang Bay, Korea. During the study period, the large-scale reclamation and dredging operations were taking place. Polychaetes were composed of 76 species with a mean density of $342\;ind.{\cdot}m^{-2}$ during the summer 1983 and 77 species with a mean density of $437\;ind.{\cdot}m^{-2}$ during the winter 1984. Community structure indices were applied to the seasonal data. The stations influenced by the Seomjin river are characterized by a low species number and low diversity, while the stations located in channel regions represent high species richness and highdiversity. The inner bay stations showed the intermediate level in terms of species richness and diversity. On the basis of taxa composition and abundance in summer, the cluster analysis indicated that the study area was divided into live regions. The main factors that govern the polychaete distributions appeared to be the fresh water run-off and bottom sediment composition. However, a slight difference was observed in winter community, and changes in composition of the dominant species were found from Lagis bocki and Chone teres to Glycinde gurjanovae and Heteromastus filiformis. As a result, the broad scale reclamation and dredging activities may have played a role in changes of the polychaete community structure and the dominant species composition in Kwangyang Bay.

• Microbiology and Biotechnology Letters
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• v.41 no.3
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• pp.300-310
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• 2013

The coastal sand-dune plants of eight species; Argusia sibirica, Calystegia soldanella, Elymus mollis, Lithospermum zollingeri, Raphanus sativus, Salsola collina, Zoysia macrostachya, and Zoysia sinica were collected from the Shindu-ri coastal sand dune. Ninety-eight endophytic fungal strains were isolated from the roots of these plants, analyzed, and identified by sequences in their internal transcribed spacers (ITS) at the ITS1, 5.8S, and ITS2 regions. The diversity of endophytic fungi isolated from coastal sand-dune plants was confirmed with various diversity indices. The fungal strains belonged to thirteen orders: Capnodiales (3.09%), Eurotiales (70.10%), Glomerellales (1.03%), Helotiales (3.09%), Hypocreales (9.28%), Mortierellales (2.06%), Onygenales (1.03%), Ophiostomatales (1.03%), Pleosporales (1.03%), Polyporales (1.03%), Russulales (1.03%), Saccharomycetales (2.06%), and Xylariales (1.03%). Of the endophytic fungal strains collected, Penicillium (59.18% in Eurotiales) and Fusarium (5.10% in Hypocreales) were the most abundant in coastal sand-dune plants. The endophytic fungal strains isolated from C. soldanella were more diverse compared to strains from the other coastal sand-dune plants.

• Journal of Biomedical Engineering Research
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• v.23 no.2
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• pp.109-117
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• 2002

Electrogastrography(EGG) is a noninvasive method for measuring gastric electrical activity on the abdomen resulting from gastric muscle. EGG signals have a very low frequency range (0.0083 ~0.15 Hz) and extremely low amplitude(10~100 uV). Consequently, EGG signal is easily influenced by other noises. Both finite impulse response(FIR) and infinite impulse response (IIR) filters need high orders or have phase distortions for passing very narrow bandwidth of the EGG signal. In this study, we decomposed EGG signals using a wavelet multiresolution method with Daubechies mother wavelet. The EGG signals were decomposed to seven levels. We reconstructed signal by summing the decomposed signals from level four to seven. To evaluate the performance of the wavelet multiresolution filter(WMF) with simulated EGG signal using two kinds of FIR and four kinds of IIR filters., we used two indices; signal to noise ratio(SNR) and reconstruction squared error(RSE). The SNR of WMF had 9.5, 6.9, and 4.7 dB bigger than that of the other filters at different noise levels, respectively. Also, The RSE of WMF had $1.22{\times}10^6, 1.16{\times}10^6, 1.02{\times}10^6$ smaller than that of the other filters at different noise levels, respectively. The WMF performed better in the SNR and RSE than two kinds of FIR and four kinds of IIR filters.

• Korean Journal of Environmental Biology
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• v.37 no.4
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• pp.447-466
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• 2019

The orchard flora where perennial fruit trees are grown may be different than in arable fields where annual crops are grown. The study focused on the floristic composition and characteristics of orchards in South Korea. The flora surveys were conducted in 36 areas in nine provinces at two times (May-June and August-September) in 2014. The results showed that the vascular orchard plants in South Korea included 466 taxa, which contained 91 families, 278 genera, 420 species, two subspecies, 39 varieties, four forms, and one hybrid. Among the 91 families, Compositae was the most diverse in species (66 taxa), followed by Gramineae (51 taxa), Leguminosae (28 taxa), Cyperaceae (18 taxa), Polygonaceae (17 taxa), Cruciferae (16 taxa), and Labiatae (14 taxa). Based on the occurrence frequency of each species, Digitaria ciliaris (Retz.) Koel. (100%) was the highest, followed by Acalypha australis L. (94.4%), Commelina communis L. (94.4%), Persicaria longiseta(Bruijn) Kitag.(91.7), Capsella bursa-pastoris(L.) L. W. Medicus(91.7%), Erigeron annuus (L.) Pers. (91.7%), Mazus pumilus (Burm. f.) Steenis (86.1%), Artemisia princeps Pamp. (86.1%), Cyperus microiria Steud. (86.1%), Stellaria aquatica (L.) Scop. (83.3%), Stellaria media(L.) Vill.(83.3%), and Echinochloa crus-galli (L.) P. Beauv.(83.3%). The biological type of orchards in South Korea was determined to be Th-₅-D₄-e type. Rare plants were found six taxa: Cinnamomum camphora (L.) J. Presl, Aristolochia contorta Bunge, Melothria japonica (Thunb.) Maxim., Ardisia crenata Sims, Gnaphalium hypoleucum DC., and Aster koraiensis Nakai. Eighty-five taxa contained naturalized plants composed of 23 families, 58 genera, 80 species, four varieties, and one form. The urbanization and naturalization indices were 26.3% and 18.2%, respectively.

• Korean Journal of Food Science and Technology
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• v.12 no.3
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• pp.200-204
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• 1980

A series of tests ware conducted to find out whether continuous heat bleaching of the refined Malaysian plam oil stored in different conditions could reduce color of the finished oil in an actual plant situation. When the refined oil was stored in a stainless steel tank and was not abused by heat during 5 month storage period, heat bleaching followed by clay bleaching and deodorization resulted in a substantial reduction in color of the finished oil in comparison to conventional process (clay bleaching of the refined oil followed by deodorization) (2.6 vs 1.3 red in Lovibond color). However, when the refined oil was stored in a carbon steel tank and was highly abused by heat in the presence of iron picked up from the tank (6.53 ppm) during the same storage period, heat bleaching followed by clay bleaching and deodorization did not help reduce color of the finished oil in comparison to the conventional process (2.7 vs 2.8 red in Lovibond color). It was also shown that oxidation values were not good indices for heat bleachability. Heat bleaching caused slight increase in polymer content of the oil. However, trans isomers were not increased when the oil was heat bleached.

• Korean Journal of Ecology and Environment
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• v.43 no.2
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• pp.175-182
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• 2010

From April to October 2008, fish fauna was surveyed at 25 sites in Lake Ganwol and Lake Bunam watersheds. There were 32 species of 25 genera and 10 families belonging to 5 orders. Among them, Zacco platypus (relative abundance was 28.0%) was dominant, followed by Hemiculter eigenmanni (24.3%), Carassius auratus (19.3%), and Pseudorasbora parva (10.8%). In comparison of specific frequency in fish community between two lakes, Z. platypus (36.6%) was dominant and P. parva (15.7%) subdominant in Lake Ganwol, whereas H. eigenmanni (35.2%) and C. auratus (30.4%) were dominant in Lake Bunam. Eight species including Acheilognathus chankaensis were known to be Korean endemic species, and exotic species was Micropterus salmodes. Biological indices of fish community indicated mostly similar values in 25 sites. Specific similarities of fish community in the sites were largely divided into two groups: a group of the Waryong Stream and the Dodang Stream where water flows throughout the year, and the other group of watersheds at Lake Ganwol and Lake Bunam where water was static. Fish fauna and structure of fish communities have some differences between Lake Ganwol and Lake Bunam watersheds, and also can be distinguished to the environmental factors of habitats in same watershed.

• Journal of Korean Society on Water Environment
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• v.32 no.5
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• pp.419-432
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• 2016

The aim of this study is to assess the influence of effluent discharge from a sewage treatment plant by evaluating oxidative stress and histopathological alterations in freshwater crucian carp Carassius auratus collected from the Eungcheon stream, located in Korea. Catalase activity in the gills, liver, and kidneys of C. auratus was collected from mixing zones; the downstream site was notably higher of fish than that of the upstream site. In addition, the activity of glutathione-S-transferase in the gills and liver was significantly higher in samples from the mixing zone than in those from the upstream site (p < 0.05). In addition, significantly elevated lipid peroxidation levels were observed in fish livers sampled from the mixing zone than in those from the upstream site (p < 0.05). Significant histopathological alternations were also observed in C. auratus, with the order of magnitude changes being liver > kidney > gills. These findings suggest that the liver is most affected by effluent discharge. The degree of tissue changes (DTC) indicate that the highest level occurred in samples from the mixing zone (30.98 ± 5.40) followed by those from the downstream site (19.28 ± 4.31) and was the lowest in samples from the upstream site (4.83 ± 2.67). These findings indicate that fish collected from the mixing zone are most affected by effluent discharge and both oxidative stress and histopathological indices are useful tools for monitoring contaminated rivers and streams.

• Journal of Korea Water Resources Association
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• v.53 no.6
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• pp.395-408
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• 2020

This paper aims to develop and apply three different machine learning approaches (i.e., artificial neural networks (ANN), adaptive neuro-fuzzy inference systems (ANFIS), and wavelet-based neural networks (WNN)) combined with an evolutionary optimization algorithm and the k-fold cross validation for multi-step (days) streamflow forecasting at the catchment located in Algeria, North Africa. The ANN and ANFIS models yielded similar performances, based on four different statistical indices (i.e., root mean squared error (RMSE), Nash-Sutcliffe efficiency (NSE), correlation coefficient (R), and peak flow criteria (PFC)) for training and testing phases. The values of RMSE and PFC for the WNN model (e.g., RMSE = 8.590 ㎥/sec, PFC = 0.252 for (t+1) day, testing phase) were lower than those of ANN (e.g., RMSE = 19.120 ㎥/sec, PFC = 0.446 for (t+1) day, testing phase) and ANFIS (e.g., RMSE = 18.520 ㎥/sec, PFC = 0.444 for (t+1) day, testing phase) models, while the values of NSE and R for WNN model were higher than those of ANNs and ANFIS models. Therefore, the new approach can be a robust tool for multi-step (days) streamflow forecasting in the Seybous River, Algeria.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.60-70
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• 2011

The sediment removal index derived from the chemical contaminants, $CI_{HC}$, is currently in use to identify and define the spatial extent of the contaminated sediments in the sea. In order to analyze the sensitivity of the ecological and human risk associated with contaminated sediment, we evaluated five hypothetical contaminated sediments, whose $CI_{HC}$ values are identical but consisted of different contaminant contents, using $TrophicTrace^{(R)}$ model dedicated to evaluate sediment risk, against the resident greenling (Hexagrammos otakii) and humans by calculating No-Observed-Adverse-Effect-Level based Toxicity Quotient (NOAEL TQ) and Lowest-Observed-Adverse-Effect-Level based Toxicity Quotient (LOAEL TQ), and cancer risks and hazard indices (HI), respectively, based on the site conceptual model and exposure assumptions of fish ingestion to human receptor populations. NOAEL and LOAEL TQ values varied as much as a factor of 2 among 5 hypothetical sediments. Chemical element specific contribution to the carcinogenic risk and HI varied also greatly in these sediments. The reason for this significant dissimilarity in ecological and human risk stems from the different risk of each contaminant to the resident fish and human receptor. When the conceptual food web model is constructed for the target biological species for a given site, the ecological and human risk analysis considering trophic transfer of contaminants will add a ecosystem based tool for the management of contaminated sediments.

• 한국해양학회지
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• v.24 no.4
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• pp.184-193
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• 1989

An investigation on the soft-bottom macrobenthic community in the inner Kyeonggi Bay was conducted in July, October of 1987 and February, May of 1988. The benthic fauna comprised a total of 87 species and showed mean density of 550 indiv./$m^2$. Major faunal groups are polychaetes, molluks, and crustaceans, corresponding to 64.7%, 17.4%, and 15.2% in total abundance respectively. The most abundant species was Tharyx sp. (10.9%), and followed by Mactra veneriformis (10.5%), Mediomastus sp. (8.6%), and Glycinde sp. (8.0%) etc.. The important species in the intertidal zone were Mactra veneriformis, Hinia festiva, and Nephtys californiensis, whereas those in subtidal channel region were Tharyx sp., mediomastus sp., Sternaspis scutata, and Nephtys polybranchia. The study area could be divided into 4 station groups based on the species composition; two groups within interidal flat and two in channel regions. Each station group sustained its specific benthic faunal assemblage; Mactra-Hinia, Aricidea-Haploscoloplos assemblages in the intertidal flat and Harpiniopsis-Urothoe, Mediomastus-Sternaspis assemblages in the subtidal channel region. The Mediomastus-Sternaspis assemblage showed the highest species number and population density, and also did the highest diversity and evenness indices. The Harpiniopsis-Urothoe assemblage showed the poor species composition and abundance, and so recorded the highest dominance index. Two assemblages in the intertidal flat had the intermediate values in all the biological parameters. The northern channel region of zone S-2 showed the high abundance in species composition, which seems to be caused by the heterogeneous sediment and the organic enrichment from the Han River and the Incheon industrial complex.