• Korean Journal of Ichthyology
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• v.26 no.4
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• pp.310-321
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• 2014

Change in fish species composition after the Hebei Spirit oil spill in December 2007 off Taean were determined by analysis of samples collected in Mailpo beach, 10 km south from the oil spill site and polluted by the crude oil. Fish samples were collected by a beach seine in the shallow water at Malipo beach during the low tide of the new moon from February 2008 to December 2009. Five seine hauls were made during the day and the night in each sampling time. Monthly day and night samples did not show the significant differences in species composition. A total of 21 species, 1,032 individuals and 6,544 g of fish were collected in 2008, and 31 species, 4,206 individuals and 35,659 g of fish in 2009. The species collected were composed of the small-sized fish or juveniles. Abundant fishes were the resident species in coastal water, and the migrants were low in abundance. Among the fish occurred, Chelon haematochelius, Sebastes schlegelii, Takifugu niphobles and Pleuronectes yokohamae were predominated in abundance of both years. Monthly fish abundance and species diversity in 2008 were significantly lower than those in 2009. A few number of resident fish were collected from February to June 2008 showing the lowest in May 2008, and fish abundance increased from July 2008. The number of species and abundance of fish in 2009 were increased in spring as the temperature raised, showed a peak in summer and decreased in autumn. This monthly variation in fish species composition and abundance was similar to those in the non-polluted water in other temperate waters. Low fish abundance during several months after oil spill was considered to be related to the residual oil in the water and habitat disturbance due to oil cleaning activity in the beach. Monthly fish species compositions after September 2008 were similar to those of 2009 suggested that the impact on the shallow water fish by the oil residuals was not too significant at least to the fish species composition after September 2008.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.5
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• pp.595-605
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• 2000

Dental ceramics have good aesthetics, biocompatibility, low thermal conductivity, abrasion resistance, and color stability. However poor resistance to fracture and shrinkage during firing process have been limiting factors in their use, particularly in multiunit ceramic restorations. A new method for making all-ceramic crowns that have high strength and low processing shrinkage has been developed and is referred to as the Vita In-Ceram method. This study was performed to investigate the effect of $CeO_2$ addition in borosilicate glasses on the strength of alumina-glass composites. Porous alumina compacts were prepared by slip casting and sintered at $1,100^{\circ}C$ for 2 hours. Dense composites were made by infiltration of molten glass into partially sintered alumina at $1,140^{\circ}C$ for 4 hours. Specimens were polished sequentially from #800 to #2000 diamond disk. and the final surface finishing on the tensile side was received an additional polishing sequence through $1{\mu}m$ diamond paste. Biaxial flexure test was conducted by using ball-on-three-ball method at a crosshead speed of 0.5mm/min. To examine the microstructural aspect of crack propagation in the alumina-glass composites, Vickers-produced indentation crack was made on the tensile surface at a load of 98.0 N and dwell time of 15 sec, and the radial crack patterns were examined by an optical microscope and a scanning electron microscope. The results obtained were summarized as follows; 1. The porosity rates of partially sintered alumina decreased with the rising of firing temperature. 2. The maximum biaxial flexure strength of 423.5MPa in alumina-glass composites was obtained with an addition of 3 mol% $CeO_2$ in glass composition and strength values showed the aspect of decrease with the increase of $CeO_2$ content. 3 The biaxial flexure strength values of alumina-glass composites were decreased with rising the firing temperature. 4. Observation of the fracture surfaces of alumina-glass composites indicated that the enhancement of strength in alumina-glass composites was due to the frictional or geometrical inter-locking of rough fracture surfaces and ligamentary bridging by intact islands of materials left behind the fracture front.

• Polymer(Korea)
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• v.27 no.5
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• pp.502-507
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• 2003

The thermal and physical properties of low density polyethylene melt-blended with Metallocene linear low density polyethylenes were investigated. Since the Metallocene polyethylenes have similar MW and MWD except m-LLDPE4, it can be said that the thermal behavior and mechanical properties of the blends depend upon the l-octene comonomer content. The melting behavior of LDPE/m-LLDPE1 blends shows two melting peaks with LDPE contents higher than 50%, while the other blends show only one melting peak. It was observed that the blends show higher crystallization temperature and higher crystallinity with lower comonomer content. Initial modulus of a blend exhibited the behavior proportional to the crystallinity and the elongation at break of the blends was increased with increasing the m-LLDPE composition. Melt indices of the blends decreased with increasing the comonomer content of Metallocene LLDPE. Melt Index values of the blends show negative deviation.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.32-37
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• 2009

An energy loss through the window system occupies about 10 to 30 percent on energy consumption of the whole building. That is the reason, several elements for a building composition of window system are the weakest from the heat. Insulation performance increases for the reducing heat loss. Heat transfer through the window system that is reducing heat transfer through conduction, convection and radiation. Insulation performance reinforcement methods classify improving heat specific quality of window system and improving efficiency of whole window system. The most application method among each methods is reducing emission ratio of the window system(Low-E glass), increasing a number of glazing(multiple window) and a method of vacuuming between glazing and glazing. Therefore this study is investigated a sort of glazing and specific character, U-value calculation with changing glazing thickness and calculation of temperature distribution and U-value with a glazing charging gas kind from double glazing. For a conclusion, an aspect of U-value figure at the smallest value case of vacuum glazing with Low-E coating. That means insulation efficiency is the best advantage during a building plan selecting vacuum glazing with Low-E coating for a energy saving aspect. In this way, U-value become different the number of glazing, coating whether or not and selecting injection gas. Therefore selecting of glazing is very important after due consideration by a characteristic and use of building and consideration of strong point and weak point.

• Korean Journal of Metals and Materials
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• v.47 no.12
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• pp.842-851
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• 2009

The long-term reliability of Sn-0.3wt%Ag-0.7wt%Cu solder joints was evaluated and compared with Sn-3.0wt%Ag-0.5wt%Cu under thermal shock conditions. Test vehicles were prepared to use Sn-0.3Ag-0.7Cu and Sn-3.0Ag-0.5Cu solder alloys. To compare the shear strength of the solder joints, 0603, 1005, 1608, 2012, 3216 and 4232 multi-layer ceramic chip capacitors were used. A reflow soldering process was utilized in the preparation of the test vehicles involving a FR-4 material-based printed circuit board (PCB). To compare the shear strength degradation following the thermal shock cycles, a thermal shock test was conducted up to 2,000 cycles at temperatures ranging from $-40^{\circ}C$ to $85^{\circ}C$, with a dwell time of 30 min at each temperature. The shear strength of the solder joints of the chip capacitors was measured at every 500 cycles in each case. The intermetallic compounds (IMCs) of the solder joint interfaces werealso analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results showed that the reliability of Sn-0.3Ag-0.7Cu solder joints was very close to that of Sn-3.0Ag-0.5Cu. Consequently, it was confirmed that Sn-0.3Ag-0.7Cu solder alloy with a low silver content can be replaced with Sn-3.0Ag-0.5Cu.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1211-1215
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• 1999

Fluorinated amorphous carbon (a-C:F) films were prepared by an electron cyclotron resonance chemical vapor deposition (ECRCVD) system using a gas mixture of $C_2F_6$ and $CH_4$ over a range of deposition temperature (room temperature ~ 300$^{\circ}C$). 500$^{\AA}C$ thick DLC films were pre-deposited on Si substrate to improve the strength between substrate and a-C:F film. The chemical bonding structure, chemical composition, surface roughness and dielectric constant of a-C:F films deposited by varying the deposition temperature were studied with a variety of techniques, such as Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), atomic force microscopy (AFM) and capacitance-voltage(C-V) measurement. Both deposition rate and fluorine content decreased linearly with increasing deposition temperature. As the deposition temperature increased from room temperature to 300$^{\circ}C$, the fluorine concentration decreased from 53.9at.% down to 41.0at.%. The dielectric constant increased from 2.45 to 2.71 with increasing the deposition temperature from room temperature to 300$^{\circ}C$. The film shrinkage was reduced with increasing deposition temperature. This results ascribed by the increased crosslinking in the films at the higher deposition temperature.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.3
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• pp.124-141
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• 1998

The objectives of this study are to investigate the trace (minor) elemental and isotopic compositions of calcitic skeletons, such as barnacle, echinoid, branching and encrusting calcareous algae and oyster, from the eastern coast of Korean peninsula and Cheju Island, and to compare their variations with latitude, that is, the temperature of ambient seawater at which the skeletons grew. Articulated and encrusting red algae are composed of high-Mg calcite (7-21 mol% $MgCO_3$). Echinoids are also composed of high-Mg calcite (7-15 mol% $MgCO_3$). Whereas barnacles are composed of low-Mg calcite (1-5 mol% $MgCO_3$). The Mg compositions of articulated red algae, barnacle and oyster tend to increase with increasing water temperature, whereas those of encrusting red algae and echinoid do not show any trend. Sr compositions of articulated red algae, echinoid and barnacle tend to decrease with increasing water temperature, whereas those of encrusting red algae and oyster do not show any trend. Mn compositions of articulated red algae and encrusting red algae decrease with an increase of water temperature, whereas those of echinoid and barnacle do not show any trend. Fe compositions of articulated red algae tend to decrease with increasing water temperature, whereas those of encrusting red algae and oyster increase. Fe compositions of echinoid and barnacle do not show any trend with water temperature variations. Ba compositions of echinoid and low-magnesium calcitic skeletons do not show any trend with water temperature variations. Ba compositions of articulated red algae tend to decrease with increasing water temperature, whereas those of encrusting red algae increase. Cd and Pb compositions of all the skeletons tend to increase with increasing water temperature. Cu compositions of encrusting red algae increase with increasing water temperature, whereas articulated red algae, echinoid, barnacle and oyster do not show any trend. Zn compositions of high-magnesium calcitic skeletons and low-magnesium calcitic skeletons do not show any trend. Estimated water temperatures from oxygen isotopic data of all the skeletons except for the barnacle arc higher than the range of temperature of the shallow seawater of the East Sea and around Cheju Island. The oxygen isotopic compositions of oyster and echinoid are well clustered, and they do not show any trend with increasing water temperature. Therefore, this could reflect that the organisms have not secreted their shells in oxygen isotopic equilibrium with ambient seawater due to vital effect. Thus, the oxygen isotopic composition of barnacle can potentially be utilized for paleotemperature estimate whereas those of other organisms in this study may not be useful.

• Korean Journal of Ichthyology
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• v.29 no.2
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• pp.130-138
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• 2017

Fish species composition in eelgrass bed of Bongam on Hansando island, Korea was determined using monthly samples collected by a surf net from August 2009 to July 2010. A total of 30 species, 3,237 individuals and 6,850.1g of fish were collected. The dominant species were Gymnogobius heptacanthus, Rudarius ercodes, Takifugu niphobles, Chaenogobius annularis, Pterogobius elapoides and Syngnathus schlegeli which accounted for 86.7% of total number of individuals of fish collected. Eelgrass started growing from May ($DW61.9g/m^2$) showing a peak biomass in August ($DW81.6g/m^2$), and low values in November ($DW57.23g/m^2$) to February ($DW15.41g/m^2$). The fish assemblages in the eelgrass beds showed clear seasonal changes; the number of fish species and individuals were low from September to December 2009, and high from December 2009 to July 2010. Seasonal variation in species composition and abundance was related to the water temperature and standing crops of eelgrass.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.205-211
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• 2019

Over the past several decades, the polymer dispersed liquid crystal (PDLC) has received particular attention as a material for developing smart window due to their electro-optical switchable properties. In this study, PDLC cells were fabricated using acrylate monomers, namely 2-hydroxyethyl acrylate (2-HEA) and ethylene glycol phenyl ether acrylate (EGPA), and the effect of the monomer composition on their electro-optical properties was investigated. The monomer mixture with a low viscosity (~10 cps) was easily filled between indium tin oxide (ITO) glasses by capillary action at room temperature. PDLC cells prepared using the mixture ratio of 1 : 9 (2-HEA : EGPA) did not show a complete opaque state at a 0 V condition but exhibited unstable electro-optical properties under an electric field. As the LC composition increased in the reaction mixture for PDLC cell preparation, the $V_{th}$ (threshold voltage) and $V_{sat}$ (saturation voltage) values as well as contrast ratio (CR) increased. $V_{th}$ and $V_{sat}$ values also increased with the cell gap thickness. PDLC cells with a $20{\mu}m$ cell gap thickness exhibited higher CR than those with 10 and $40{\mu}m$ cell gap thicknesses. Particularly, PDLC cells prepared using the mixture ratio of 7 : 3 (2-HEA : EGPA) showed excellent electro-optical properties such as a low driving voltage and high contrast ratio.

• Food Science and Preservation
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• v.23 no.6
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• pp.765-771
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• 2016

Omija-cheong, concentrated extracts from sugar-treated Omija fruit (Schisandra chinensis Baillon), is produced by traditional manner in Korea. The quality characteristics of Omija-cheong processed at low temperature with a pilot-scale were investigated to optimize the incubation time. With increasing incubation time in processing Omija-cheong, the pH level of Omija-cheong remained constant, while titratable acidity and organic acids increased. Fresh Omija fruits contained citric, malic and succinic acids, most of which were extracted into concentrated extracts after 37 days of incubation and reached to the stable concentration after 47 days of incubation. Titratable acidity in Omija-cheong gradually increased from 1.18% to 2.71%, and also was correlated with total concentration of organic acids. About 80% of supplemented sucrose for manufacturing Omija-cheong was converted into glucose and fructose until 68 days of incubation, and the composition of free sugars was maintained to be stable up to 138 days of incubation. The contents of total flavonoids and phenolic compounds in Omija-cheong were 24.1 mg-GAE/L and 1,635 mg-QE/L at 57 days of incubation, which were more than 9 and 5 times higher than those in Omija fruits, respectively. From the quality characteristics in processing Omija-cheong by low-temperature incubation, more than 60 days of incubation is required for the constant quality and value-added beverage.