• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.3
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• pp.190-200
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• 2001

An ecological study was performed to investigate the community structure of the benthic macrofaunal assemblage on the Cheokjeon tidal flat, Incheon, Korea. Benthic samples were collected between Sept. 1990 and July1992 at three stations to compare environmental factors with the structure of benthic community among station sand seasons. Overall, macrofauna comprised a total of 111 species, and the mean density (708.1 md./$m^2$) and biomass (214.9gWWt/$m^2$). The number of species and individuals of polychaetes, molluscs and crustaceans made up more than 80% of the total number. On the other hand, in terms of biomass, bivalves and holothuroideans indicated that they were the dominant faunal groups. Hierarchical classification using the Bray-Curtis coefficient categorized samples into 3 station and 4 faunal groups. In terms of q-mode, there consisted of upper, middle and low tidal flat stations, respectively. And four faunistic groups were established as follows: 1) Heteromastus filifomis-Mactra veneriformis-Solen strictus-Ilyoplax finggi (wide-ranging elevation specialists), 2)Nephtys chemulpoensis-Macrophthalmus gaponicus (high elevation specialists), 3) Glycera subaenea-Decorifer matusimana-Tritodynamia (middle elevation specialists) and 4) Nephtys polybranchia-Borniopsis tsurumaru-Asthenognathus inaequipes-Protankyra bidentata (low elevation Specialists).

• Journal of Korean Society on Water Environment
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• v.39 no.1
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• pp.61-75
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• 2023

Denitrifying bacteria convert nitrate to nitrogen gas using an external carbon source as an electron donor. The external carbon source affects the denitrification performance and bacterial community structure. Although methanol is a cheap and effective external carbon source, the addition of diverse carbon sources may improve the total nitrogen removal rate and biomass characteristics, such as settleability. In this study, denitrifying reactions were performed using solely methanol and mixed carbon sources of methanol, glucose, and acetate in a sequencing batch reactor. The denitrifying reactor using methanol resulted in a total nitrogen removal rate of 0.39 ± 0.025 kg-N/m³-day while the suspended biomass transformed into dark brown granules. Methyloversatilis discipulorum had the highest predominance at 43.84%. The individual denitrifying biomasses, which were separately enriched with methanol, glucose, and acetate, showed the same total nitrogen removal performance of 0.39 ± 0.016 kg-N/m³-day. However, the addition of mixed carbon sources showed an improved total nitrogen removal rate of 0.42 ± 0.043 kg-N/m³-day, with the domination of Candidatus Saccaribacteria at 25.61%. The denitrifying granules turned pale yellow color. Influent COD/NO₃^--N ratios of 3.5, 5, and 7.5 exhibited COD/NO₃^--N consumptions of 4.3 ± 0.4, 4.4 ± 0.8, and 5.2 ± 0.7, and the consistent predominance of Candidatus Saccharibacteria.

• Korean Journal of Environmental Biology
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• v.28 no.4
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• pp.179-187
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• 2010

The Theory of Island Biogeography describes that the number of species on an island affected by island area and distance from the mainland. This study was performed to compare and analyze the community structure of the macro-invertebrates in three isolated islands, around Korean waters in terms of the Theory of Island Biogeography. Macrobenthic animals were collected using a modified underwater quadrat in August 2009. A total of 104 macrobenthic species were sampled with a mean density of 399 individuals $m^{-2}$ and biomass of 1,506.70 g $m^{-2}$. Based on the abundance and biomass data, there were 10 dominant species accounting for approximately 67.17% of total individuals. The highest densities were found in the amphipoda Amphipoda spp., the bivalvia Modiolus agripetus and Mytilus coruscus, the Sipunculida Phascolosoma scolops and the polychaeta Syllidae unid.. On the contrary, the top ten species made up 95.66% of the total biomass while the three most abundant, the bivalves M. coruscus, Streostria circumpicta and M. agripetus. The conventional multi-variate statistics (cluster analysis and non-metric multi-dimensional scaling) applied to assess spatial variation in macrobenthic assemblages. Cluster analysis and nMDS ordination analysis based on the Bray-Curtis similarity identified 2 station groups. The group 1 was consisted with Gageodo (except for lower station at Transect 2) and Dokdo station and was numerically dominated by the polychaetes Eunice antennata and Syllidae unid., the cirripedia Megabalanus rosa and the bivalvia M. coruscus. However, group 2 was associated with Sohwado station and was characterized by high abundance of the anomura Petrolisthes japonicus, the gastropoda Lirularia pygmaea and the brachiopoda Coptothyris grayi. In conclusion, these results suggested that the species diversity and community structure of macrobenthos in three isolated island seemed slightly related to island area and distance from the mainland.

• Journal of Microbiology
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• v.42 no.4
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• pp.267-277
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• 2004

Effects of elevated $CO_2$ on soil microorganisms are known to be mediated by various interactions with plants, for which such effects are relatively poorly documented. In this review, we summarize and syn­thesize results from studies assessing impacts of elevated $CO_2$ on soil ecosystems, focusing primarily on plants and a variety the of microbial processes. The processes considered include changes in microbial biomass of C and N, microbial number, respiration rates, organic matter decomposition, soil enzyme activities, microbial community composition, and functional groups of bacteria mediating trace gas emission such as methane and nitrous oxide. Elevated $CO_2$ in atmosphere may enhance certain micro­bial processes such as $CH_4$ emission from wetlands due to enhanced carbon supply from plants. How­ever, responses of extracellular enzyme activities and microbial community structure are still controversy, because interferences with other factors such as the types of plants, nutrient availabilitial in soil, soil types, analysis methods, and types of $CO_2$ fumigation systems are not fully understood.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.1
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• pp.257-269
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• 2017

The occurrence variations of decapods by season and depth off Oryuk Islets, Busan were investigated at seven stations in April and October 2009, July 2010 and January 2011. Decapods were collected by SCUBA diving at 5 m and 10 m depths. 46 species belonging to 18 families in 3 orders were identified. Pilumnus minutus, Pugettia intermedia, Pachycheles stevensii, and Paguristes japonicus were dominant species, comprising 73.0% of total decapods. P. minutus and P. intermedia were abundant in all seasons (except summer) while P. stevensii and P. japonicus were abundant in fall and summer. Dominant species were divided into three groups (resident species, seasonal species and temporary species) on the basis of their occurrence patterns. P. minutus and P. intermedia were resident species while P. stevensii, P. japonicus were temporary species. The species number, density and biomass of decapods were fluctuated by seasons. They were highest in fall and lowest in winter. This study implied that the variations of species number and density of decapods were significantly related with seasonal change of water temperature.

• Ocean and Polar Research
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• v.38 no.4
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• pp.315-324
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• 2016

In this study, we investigated changes in the macrobenthic community in Sihwa tidal flat before and after the operation of a Tidal Power Plant (TPP). In order to investigate changes in the macrobenthic community structure, field surveys were conducted at eighteen stations in 4 transect lines every September from 2011 to 2015. Mean density of macrobenthos decreased to $116ind./m^2$ in 2015 from $1,602ind./m^2$ in 2011. While the mean density of macrobenthos has decreased, species richness and biomass have gradually increased. The species diversity and SEP (Shannon-wiener Evenness Proportion) have also gradually increased over time since the operation of the TPP. The macrobenthic community in Sihwa tidal flat was divided into 4 groups on a yearly base. Before the operation of TPP, opportunistic species such as Neanthes succina and Polydora cornuta largely contributed to the structure of the macrobenthic community, while equilibrium species such as Periserrula leucophryna and Scopimera globosa contributed after the operation. With the operation of TPP, the macrobenthic community has rapidly recovered and this might be related to improvement in the quality of water and sedimentary environments as a result of an increase in water mass volume exchanged through the TPP gate.

• Journal of Electrochemical Science and Technology
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• v.12 no.2
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• pp.285-295
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• 2021

The inverse spinel Cobalt ferrite (CoFe₂O₄, CFO) is considered to be a promising alternative to commercial graphite anodes for lithium ion batteries (LIBs). However, the further development of CFO is limited by its unstable structure during battery cycling and low electrical conductivity. In an effort to address the challenge, we construct three-dimensional hierarchical flower-like CFO nanoclusters (CFO NCs)-decorated carbonized cotton carbon fiber (CFO NCs/CCF) composite. This structure is consisted of microfibers and nanoflower cluster composited of CFO nanoparticle, in which CCF can be used as a long-range conductive matrix, while flower-like CFO NCs can provide abundant active sites, large electrode/electrolyte interface, short lithium ion diffusion path, and alleviated structural stress. As anode materials in LIBs, the flower-like CFO NCs/CCF exhibits excellent electrochemical performance. After 100 cycles at a current density of 0.3 A g^-1, the CFO NCs/CCF delivers a discharge/charge capacity of 1008/990 mAh g^-1. Even at a high current density of 15 A g^-1, it still maintains a charge/discharge capacity of 362/361 mAh g^-1.

• Journal of Environmental Science International
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• v.17 no.10
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• pp.1155-1167
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• 2008

Chlorophyll a (chl a) has been used as an indicator for phytoplankton biomass in pelagic ecosystems due to the relative ease of measurement and selectivity for autotrophs in mixed plankton assemblages. However, the use of chi a as an indicator for phytoplankton biomass is restricted due to its inability to resolve taxonomic differences of phytoplankton and the highly variable relationship of chi a with phytoplankton. Here, we describe the analysis of High-Performance Liquid Chromatography (HPLC) photosynthetic pigment data using CHEMTAX, which is a matrix factorization program that uses chemical taxonomic indices (phytoplankton carotenoids) to quantify the abundance of phytoplankton groups. Compared to direct microscopic counting that can distinguish species within broad groups, the resolution of taxonomic groups by CHEMTAX is generally coarse. It can only distinguish between diatoms, dinoflagellates, cryptophytes, cyanobacteria, chlorophytes, prasinophytes, and haptophytes. However, CHEMTAX analysis is much faster and less expensive than microscopic counting methods. HPLC pigment observations were taken in the spring, summer, fall, and winter in$ 2005\sim2006$ within Gamak Bay, South Korea. CHEMTAX results revealed that diatoms were the dominant taxonomic group in Gamak Bay. In inner Gamak Bay, the ratio between diatoms and cryptophytes was $75\sim80%$, and the ratio between dinoflagellates and cryptophytes was $10\sim15%$. In outer Gamak Bay, the ratio between diatoms and cryptophytes was $85\sim90%$, and the ratio between dinflagellates and cryptophytes was only $1\sim5%$. The population structure was seasonal. Relative diatom populations were less in the summer than the winter season.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.137.1-137.1
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• 2010

For Indonesia, sustainable energy supply is an important factor to preserve the stable economic growth. One important strategy is development of renewable energy, which has not been fully exploited yet. The paper examines the potency of renewable energy in Indonesia. Currently, biomass composes 23% of total primary energy supply, while geothermal and hydropower has a combined share of 3%. But according to the overall potency of renewable energy, hydropower is found to have the highest available resource of 76 GW, followed by biomass and geothermal by 49.81 GW and 28.53 GW, respectively. Although the solar radiation is only at modest level ($4.80kWh/m^2/day$), the tropical all year sunlight can boost the competitiveness of solar photovoltaic and thermal application. As for wind energy, the average speed of 3-6 m/s requires the development of low speed wind turbine. The examination of electricity and petroleum product prices through international comparison for non-OECD countries shows fifth lowest price level for both of petroleum products and electricity for industrial use. As for household electricity price, Indonesia is placed the second among all the countries compared. The energy subsidy and price structure are examined in detail because it could be a source of hindrance to renewable energy promotion. The examination of renewable energy potency in this study could provide insights about recent development of renewable energy in Indonesia. As an outcome of policy examination, the price comparison analysis suggests Indonesia to reduce or even remove the energy subsidies in the long run. These findings can be utilized to formulate effective policies for renewable energy promotion.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.3
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• pp.213-222
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• 2020

Species composition and seasonal variations of fish in the Five West Sea Islands in Korea, were investigated by using otter trawls and bongo nets from 2014 to 2015. During the surveyed period using an otter trawl, a total of 53 species, 147,253 ind./㎢ and 2,721,296 g/㎢ of fish were collected by otter trawls. The individual dominant species were Chaeturichthys stigmatias (30.3%), Coilia nasus (18.2%), Engraulis japonicus (12.3%), and Setipinna tenuifilis (12.2%). Moreover, the biomass dominant species in biomass were Liparis tanakae (21.3%), Beringraja pulchra (18.5%), Engraulis japonicus (8.3%) and Okamejei kenojei (8.1%). Eggs by bongo nets included 1,748 ind./1,000 ㎥ of Engraulis japonicus and 64,691 ind./1,000 ㎥ of unidentified species. A total of 15 species and 2,015 ind./1,000 ㎥ of fish larvae were collected, and the dominant species were Johnius belengerii and Pholis fangi.