• ALGAE
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• v.23 no.4
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• pp.317-326
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• 2008

Marine algal flora and community structure were investigated seasonally at three sites in Ilkwang Bay on the southern east coast of Korea from May 2007 to February 2008. Total 103 species including 10 of green algae, 17 of brown algae, 76 of red algae were collected and identified. Among these species, 21 species were found throughout the year. Ulva pertusa, Enteromorpha linza, Grateloupia lanceolata, Chondracanthus intermedia and Caulacanthus ustulatus were distributed dominantly in upper intertidal zone. By contrast, crustose coralline algae, Grateloupia spp., Chondracanthus tenellus, Prionitis cornea and Sargassum spp. occurred predominantly in middle intertidal zone. Grateloupia spp., Sargassum spp., Ecklonia cava and Ulva pertusa were dominant in lower intertidal zone. Annual mean biomass in wet weight was 478.3 g m$^{-2}$. Maximum biomass was recorded in site 1 (731.8 g m$^{-2}$), and minimum was recorded in site 3 (78.5 g m$^{-2}$). The R/P, C/P and (R + C)/P value reflecting flora characteristics were 4.47, 0.59 and 5.06, respectively. Two groups produced by cluster analysis, one including sites 1, 2 and the other including site 3, showed meaningful difference in similarity, each other. Site 3 showed the limited species composition due to inflow of fresh water and absence of solid substratum. However, there was no significant difference between site 1 and site 2. In conclusion, the number of marine algae species and biomass in Ilkwang Bay were markedly reduced comparing with the previous studies. These suggest that a solution for reconstruction of the poor marine algal vegetation is considerably demanded.

• Journal of Pharmaceutical Investigation
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• v.5 no.3
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• pp.50-57
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• 1975

Bismuthsubgallate is a compound of indefinite composition containing bismuth and gallic acid. Because its structure was indefinite, many papers have been reported for it. But these are different one another and the relationship between the physical properties, structure and manufacturing condition has not been yet reported. In this experiment, bismuthsubgallate was prepared from bismuthsubgallate and gallic acid in an acetic medium at $65^{\circ}$, and dried at four different temperatures $30^{\circ}\;65^{\circ}\;105^{\circ}\;and\;155^{\circ}$. And some of the other relative bismuth organic compounds were prepared. To each product. elemental analysis, IR spectra and DTA, TGA curves were determined. These results revealed the followings; l. The structure of bismuthsubgallate is comfirmed as a complex form of gallomonohydroxo-bismutic acid monohydrate and its yellow colour dependent upon complex anion in the structure. 2. According to the drying temperature, the hydrate content of bismuthsubgallate is quite different: dihydrate at room temperature, mono-hydrate at. $65^{\circ}$, anhydrous at $105^{\circ}$ and decomposed partial1y oganic substance of the structure above $155^{\circ}$.

• Clean Technology
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• v.26 no.4
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• pp.263-269
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• 2020

Zeolite was synthesized hydrothermally using the water-treatment sludge, and the effects of various synthesis parameters like reaction temperature, reaction time, and Na2O/SiO2 molar ratio on the crystallization of zeolite were investigated. Crystal structure, physical property, and thermal stability of zeolite crystals were characterized by X-ray powder diffraction, FTIR spectroscopy, BET nitrogen adsorption, and TGA measurements. The removal efficiencies of nitrogen in ammonia, heavy metal ions, and TOC were calculated to evaluate zeolite's adsorption capacity. The primary chemical composition of water-treatment sludge was 28.79% Al2O3 and 27.06% SiO2. The zeolites were synthesized by merely employing the water-treatment sludge as silica and alumina sources without additional chemicals. Zeolite crystals synthesized through the water-treatment sludge were confirmed as an A-type zeolite structure. Zeolite A had the highest crystallinity obtained from a gel with the molar composition 2.1Na2O-Al2O3-1.6SiO2-65H2O after 5 h at a temperature of 90 ℃. The specific surface area of zeolite obtained was 55 ㎡ g-1, which was higher than commercial zeolite A. The removal efficiency of nitrogen in ammonia was 68% after 3 h of reaction time, while the removal efficiencies of Pb2+ and Cd2+ ions were 99.1% and 99.3%, respectively. These results indicate active ion exchange between Pb2+ or Cd2+ ion and Na+ ion in the zeolite framework. The adsorption experiments on the different zeolite addition conditions were performed for 3 h with 300 ppm humic acid. Based on the results, TOC's highest efficiency was 83% when 5 g of zeolite was added.

• Korean Journal of Materials Research
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• v.31 no.11
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• pp.593-600
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• 2021

Herein, a series of g-C₃N₄ modified Bi₂MoO₆ nanocomposites using Bi₂MoO₆ and melamine as original materials are fabricated via sintering process. For presynthesis of Bi₂MoO₆ an ultrasonic-assisted hydrothermal technique is researched. The structure and composition of the nanocomposites are characterized by Raman spectroscopy, X-ray diffraction (XRD), and high-resolution field emission scanning electron microscopy (SEM). The improved photoelectrochemical properties are studied by photocurrent density, EIS, and amperometric i-t curve analysis. It is found that the structure of Bi₂MoO₆ nanoparticles remains intact, with good dispersion status. The as-prepared g-C₃N₄/Bi₂MoO₆ nanocomposites (BMC 5-9) are selected and investigated by SEM analysis, which inhibits special morphology consisting of Bi₂MoO₆ nanoparticles and some g-C₃N₄ nanosheets. The introduction of small sized g-C₃N₄ nanosheets in sample BMC 9 is effective to improve the charge separation and transfer efficiency, resulting in enhancing of the photoelectric behavior of Bi₂MoO₆. The improved photoelectronic behavior of g-C₃N₄/Bi₂MoO₆ may be attributed to enhanced charge separation efficiency, photocurrent stability, and fast electron transport pathways for some energy applications.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.1
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• pp.9-18
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• 2023

Fish samples were collected by a set net from April to December 2020 at the coastal waters off Tongyeong, Korea to determine fish species composition and seasonal variation. A total of 330,675 fish (1,032,578 g) representing 56 species belonging to 39 families were collected during the sampling period. The dominant species were Engraulis japonicus, Trachurus japonicus and Trichiurus japonicus, which accounted for 98.1% of the total number of individuals and 87.5% of the total biomass collected. E. japonicus and Chelidonichthys spinosus appeared every month off the coast of the Tongyeong. Cluster analysis based on the number of individuals of fish were classified into two groups at the dissimilarity level of 57%, and the results of ANOSIM analysis revealed significant differences in community structure among the two groups.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.5
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• pp.768-775
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• 2015

Seasonal variability in the marine seaweed community structure was examined in the intertidal zones at nine study sites in Hallyeohaesang National Park, on the southern coast of Korea from March to October 2014. A total of 145 seaweeds were indentified, comprising 15 green, 41 brown and 89 red algae. Coarsely branched seaweeds were the dominant functional group, comprising 58.95% in species number, whereas filamentous, sheet, thick leathery, crustose and jointed calcareous forms comprised 2.63-17.72% each. The seaweed biomass averaged 358.00 g dry wt/m² and it was maximal at Somaemuldo (847.64 g dry wt/m²) and minimal at Gamam (56.51 g dry wt/m²). Based on biomass, the dominant and subdominant seaweeds were Ulva australis at Gamam, Sargassum thunbergii at Sangju, Ulva australis and S.fulvellum at Neukdo, S.horneri at Dala-Bijindo-Somaemuldo, S. thunbergii at Dapo, and Corallina pilulifera at Songdo. Community indices were as follows: dominance index (DI), 0.43-0.71; richness index (R), 8.26-16.50; evenness index (J'), 0.36-0.54; and diversity index (H'), 1.57-2.19. In conclusion, we found that both biomass and the community structure of seaweeds in Hallyeohaesang National Park were similar to those in other studies of the Southern Sea along the Korean peninsula, and that Hallyeohaesang National Park is a relatively favorable habitat for seaweeds. Future studies should examine the changes in seaweed composition and biomass as they relate to climate change and environmental pollution.

• Korean Journal of Crystallography
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• v.12 no.1
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• pp.20-24
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• 2001

NiZn-ferrite was synthesized usign waste iron oxide catalysts which were produced from styrene monomer process and buried underground as an industrial wastes. The spinel type ferrite was obtained by calcination and sintering of the mixture of finely ground waste catalysts, nickel oxide and zinc oxide powders. The sintered body of Ni/sub 0.5/Zn/sub 0.5/Fe₂O₄ composition at 1230℃ for 5 hours showed the density of 5.38g/㎤, and initial permeability of 59 at 1 kHz. Not only cerium oxide, which existed as a major component in the catalyst, but also unicorporated NiO and ZnO into spinel structure remained as second phases after sintering.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.2
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• pp.90-94
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• 2016

In this work, [$Pb(Mg_{1/2}W_{1/2})_{0.03}(Ni_{1/3}Nb_{2/3})_x(Zr_{0.5}Ti_{0.5})_{0.97-x}O_3-BiFeO_3$] (x=0.02 to 0.12) composition ceramics were fabricated by the conventional soild state reaction method and their microstructure and piezoelectric properties were investigated according to PNN substitution. The addition of small amount of $BiFeO_3$, $Li_2CO_3$, and $CaCO_3$ were used in order to decrease the sintering temperature of the ceramics. The XRD (x-ray diffraction patterns) of all ceramics exhibited a perovskite structure. The sinterability of PMW-PNN-PZT-BF ceramics was remarkably improved using liquid phase sintering of $CaCO_3$, $Li_2CO_3$. However, it was identified from of the X-ray diffraction patterns that the secondary phase formed in grain boundaries decreased the piezoelectric properties. According to the substitution of PNN, the crystal structure of ceramics is transformed gradually from a tetragonal to rhombohedral phase. The x=0.10 mol PNN-substituted PMW-PNN-PZT-BF ceramics sintered at $920^{\circ}C$ showed the optimum values of piezoelectric constant($d_{33}$), piezoelectric figure of merit($d_{33{\cdot}}g_{33}$), planar piezoelectric coupling coefficient($k_p$) and density : $d_{33}=566$ [pC/N], $g_{33}=29.28[10^{-3}mV/N]$, $d_{33{\cdot}}g_{33}=16.57[pm^2/N]$, $k_p=0.61$, density=7.82 [$g/cm^3$], suitable for duplex ultrasonic sensor application.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.115-117
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• 2001

$Ba(Zn_{1-x}Co_x)TaO_3$[BZCT] ceramics were prepared by the conventional mixed oxide method. The ceramics were sintered at the temperature of $1450{\sim}1550^{\circ}C$ for 5hr. in air. The structural properties of the BZCT ceramics as a function of composition and sintering temperature were investigated by the XRD and SEM. The crystal structure of BZCT ceramics was investigated by the XRD. The microstructure of the specimens were observed by SEM. All the BZCT ceramics sintered above the $1550^{\circ}C$ were showed as a polycrystalline complex perovskite structure without second phases and any unreacted materials. The density of BZCT (70/30) specimen sintered at $1550^{\circ}C$ was $6.31g/cm^3$.

• Elastomers and Composites
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• v.47 no.1
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• pp.30-35
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• 2012

Novel bio-polybutadiene polymers with controlled molecular weight (MW), MW distribution, chemical composition and micro structure were synthesized by a living anionic polymerization of butadiene and the subsequent coupling reaction of the thus obtained living polybutadiene and a vegetable oil. Anionic polymerization of butadiene was carried out in THF solvent using n-BuLi initiator. The resulting living polybutadienyllithium polymer was then reacted with epoxidized soybean oil (ESO) to obtain a star-polymer of polybutadiene and vegitable oil. Three different bio-elastomers were prepared by coupling living polybutadienes of MWs 1000, 5000 and 1000g/mol with ESO. The molecular structure and MW of the polybutadienes and bioelastomers were characterized by $^1H$-NMR, FTIR and GPC techniques.