• The Korean Journal of Physiology and Pharmacology
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• v.3 no.3
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• pp.237-244
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• 1999

Magnesium ion is known to selectively block the N-methyl-D-aspartate (NMDA)-induced responses and to have anticonvulsive action, neuroprotective effect and antinociceptive action in the behavioral test. In this study, we investigated the effect of $Mg^{2+}$ on the responses of dorsal horn neurons to cutaneous thermal stimulation and graded electrical stimulation of afferent nerves as well as to excitatory amino acids and also elucidated whether the actions of $Ca^{2+}$ and $Mg^{2+}$ are additive or antagonistic. $Mg^{2+}$ suppressed the thermal and C-fiber responses of wide dynamic range (WDR) cell without any effect on the A-fiber responses. When $Mg^{2+}$ was directly applied onto the spinal cord, its inhibitory effect was dependent on the concentration of $Mg^{2+}$ and duration of application. The NMDA- and kainate-induced responses of WDR cell were suppressed by $Mg^{2+}$, the NMDA-induced responses being inhibited more strongly. $Ca^{2+}$ also inhibited the NMDA-induced responses current-dependently. Both inhibitory actions of $Mg^{2+}$ and $Ca^{2+}$ were additive, while $Mg^{2+}$ suppressed the EGTA-induced augmentation of WDR cell responses to NMDA and C-fiber stimulation. Magnesium had dual effects on the spontaneous activities of WDR cell. These experimental findings suggest that $Mg^{2+}$ is implicated in the modulation of pain in the rat spinal cord by inhibiting the responses of WDR cell to noxious stimuli more strongly than innocuous stimuli.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.6
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• pp.823-829
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• 2016

Yacon (YC), ginger (GG) and blueberry (BB) were added to the diet of juvenile rockfish Sebastes schlegeli to investigate the effects of these substances on growth, feed utilization and resistance to Streptococcus iniae compared to feed additive ethoxyquin. A total of 480 fish were distributed in 12 tanks and four experimental diets [control (Con), with 0.01% ethoxyquin, and 1% YC, GG and BB diets] were provided in triplicate. After an 8-week feeding trial, 20 fish from each tank were infected with Streptococcus iniae. Fish fed the BB diet had higher weight gain than fish fed the GG and Con diets. Feed efficiency of fish fed the GG and YC diets was higher than that of fish fed the BB and Con diets. The protein efficiency ratio of fish fed the GG diet was higher than that of fish fed any other diet. The cumulative mortality 54 h after infection of fish fed the Con diet was higher than that of fish fed any other diet. These results indicate that YC, GG, and BB are effective dietary additive, not only improving growth performance and feed utilization but also lowering the mortality of juvenile rockfish exposed to S. iniae.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.545-545
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• 2008

Poly-Si is an essential material for floating gate in NAND Flash memory. To fabricate this material within region of floating gate, chemical mechanical polishing (CMP) is commonly used process for manufacturing NAND flash memory. We use colloidal silica abrasive with alkaline agent, polymeric additive and organic surfactant to obtain high Poly-Si to SiO2 film selectivity and reduce surface defect in Poly-Si CMP. We already studied about the effects of alkaline agent and polymeric additive. But the effect of organic surfactant in Poly-Si CMP is not clearly defined. So we will examine the function of organic surfactant in Poly-Si CMP with concentration separation test. We expect that surface roughness will be improved with the addition of organic surfactant as the case of wafering CMP. Poly-Si wafer are deposited by low pressure chemical vapor deposition (LPCVD) and oxide film are prepared by the method of plasma-enhanced tetra ethyl ortho silicate (PETEOS). The polishing test will be performed by a Strasbaugh 6EC polisher with an IC1000/Suba IV stacked pad and the pad will be conditioned by ex situ diamond disk. And the thickness difference of wafer between before and after polishing test will be measured by Ellipsometer and Nanospec. The roughness of Poly-Si film will be analyzed by atomic force microscope.

• Genomics & Informatics
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• v.7 no.1
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• pp.13-19
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• 2009

Osteoporosis is characterized by impaired osteogenesis. BMD is a major determinant of bone strength. The role of the VDR gene in predisposition to primary osteoporosis has been recognized. However, population-based case-control studies have been reported controversial results for known candidate genes in an ethnically distinct group. To determine the genetic effects of VDR variants on osteoporosis and BMD, we directly sequenced the VDR gene in 24 unrelated Korean individuals and identified eighteen sequence variants. We investigated the potential involvement of eight SNPs in osteoporosis in postmenopausal women (n = 729). Two SNPs (LD) in intron 2, -5294G>C (rs2238135) and -4817G>A (rs17882443) showed the evidence of association with enhanced BMD of the femoral neck ($p_{additive}$=0.031 for rs2238135; $p_{additive}$=0.017 and $p_{dominant}$= 0.019 for 17882443). Moreover, VDR -4817G>A was significantly associated with protective effect on all fracture risk ($p_{recessive}$=0.035, OR=0.2, 95% CI=$0.05{\sim}0.89$), and tended to be higher BMD values at various proximal femur sites. Therefore, we suggest that the -4817G>A may be useful genetic marker for vitamin D-related metabolism and may have an important role in the increased BMD of the proximal femur in postmenopausal Korean women.

• Journal of Environmental Health Sciences
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• v.35 no.1
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• pp.1-10
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• 2009

This study assessed the relationships between levels of $PM_{10}$ and hospitalization rates for asthma among children from 2003 to 2005 at four major cities in Korea. In addition, we estimated the reduced number of asthma hospitalization associated with an ambient $PM_{10}$ improvement to the acceptable levels as recommended by the World Health Organization (WHO). The Generalized Additive Model (GAM) was used to estimate the relative risks (RR) of asthma hospitalization associated with changes in $PM_{10}$ The RRs of children's asthma hospitalization for every $10{\mu}g/m^3$ increment in $PM_{10}$ were 1.009(95% CI = 1.004-1.014) in Seoul, 1.013(95% CI = 1.006-1.021) in Incheon, 1.009(95% CI = 1.002-1.016) in Busan, and 1.021(95% CI = 1.005-1.037) in Ulsan. We assessed $PM_{10}$ related health benefits from implementing the WHO's guidelines (24-hour average $50{\mu}g/m^3$) using the U.S. Environmental Protection Agency's Environmental Benefits Mapping and Analysis Program. The estimated benefits were 439(95% CI = 216-666) reduced asthma hospitalization in Seoul, 720(95% CI = 304-1,151) in Incheon, 260(95% CI = 66-459) in Busan, and 126(95% CI = 30-228) in Ulsan. It was concluded that improving $PM_{10}$ condition to the WHO guideline would make a significant contribution to the reduction in asthma hospitalization among children. Therefore, public health measures are still needed to improve air quality in Korea.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.3
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• pp.276-282
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• 2016

The effects of conductive additives in a $La_{0.8}Sr_{0.2}MnO_3$ perovskite bifunctional electrode for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were investigated in an alkaline solution. Highly porous carbon black (CB) and Ni powder were added to the bifunctional electrodes as conductive additives. The surface morphologies of electrodes containing CB and Ni were observed by scanning electron microscopy (SEM). The current densities for both ORR and OER were changed by the addition of CB. The conductive additive changed physical properties of bifunctional electrodes such as the sheet conductance, gas permeability and contact angle. It was observed that the air permeability of electrode was most effective to enhance the currents for ORR and OER.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.289-293
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• 2003

This study dealt with the characterization of $MoSi_2$ based composites containing three types of additive materials such as SiC, $NbSi_2\;and\;ZrO_2$ particles have been investigated, based on the detailed examination of their microstructures and fracture surfaces. The effects of reinforcing materials on the high temperature strength of $MoSi_2$ based composites have been also examined. $MoSi_2$ based composites were fabricated by the hot press process under the vacuum atmosphere. The volume fraction of reinforcing materials in the composite system was fixed as 20 %. The microstructures and the mechanical properties of $MoSi_2$ based composites were investigated by means of SEM, EDS, XRD and three point bending test.

• Korean Journal of Materials Research
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• v.22 no.7
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• pp.374-378
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• 2012

In an effort to overcome the problems which arise when fabricating high-aspect-ratio TSV(through silicon via), we performed experiments involving the void-free Cu filling of a TSV(10~20 ${\mu}m$ in diameter with an aspect ratio of 5~7) by controlling the plating DC current density and the additive SPS concentration. Initially, the copper deposit growth mode in and around the trench and the TSV was estimated by the change in the plating DC current density. According to the variation of the plating current density, the deposition rate during Cu electroplating differed at the top and the bottom of the trench. Specifically, at a current density 2.5 mA/$cm^2$, the deposition rate in the corner of the trench was lower than that at the top and on the bottom sides. From this result, we confirmed that a plating current density 2.5 mA/$cm^2$ is very useful for void-free Cu filling of a TSV. In order to reduce the plating time, we attempted TSV Cu filling by controlling the accelerator SPS concentration at a plating current density of 2.5 mA/$cm^2$. A TSV with a diameter 10 ${\mu}m$ and an aspect ratio of 7 was filled completely with Cu plating material in 90 min at a current density 2.5 mA/$cm^2$ with an addition of SPS at 50 mg/L. Finally, we found that TSV can be filled rapidly with plated Cu without voids by controlling the SPS concentration at the optimized plating current density.

• Journal of Ocean Engineering and Technology
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• v.21 no.6
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• pp.95-100
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• 2007

In the present work, silicon nitride was fabricated with $Y_3Al_5O_{12}$ as a sintering additive and its mechanical properties were investigated. Silicon nitride with 3, 5, and 7wt% of $Y_3Al_5O_{12}$ was prepared and sintered by a Hot Pressing (HP) technique at 1750 and $1800^{\circ}C$ for 2 h. The process was performed under different process pressures of 30 and 45 MPa. Mechanical properties (density, strength, hardness, and fracture toughness) were investigated as a function of the $Y_3Al_5O_{12}$ content in $Si_3N_4$. $Si_3N_4\;-Y_3Al_5O_{12}$ ceramics showing similar mechanical properties compared with $Si_3N_4-Y_2O_3-Al_2O_3$ ceramics. But its high temperature strength was considerably higher than that of $Si_3N_4-Y_2O_3-Al_2O_3$ ceramics.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.177-184
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• 2021

In this study, the effects of ground granulated blast furnace slag(GGBFS) and expansive additive(EA) on early strength mortar were examined for the purpose of reducing carbon and improving cement performance. As a result, ealry strength Portland cement(EPC) tended to decrease in flow compared to ordinary Portland cement(OPC), but binder with EPC and GGBFS was possible to obtain higher liquidity than OPC. EPC showed higher compressive strength and shrinkage than OPC. The compressive strength of specimen with EPC and GGBFS was reduced proportionally to the replacement ratio of GGBFS. The replacement ratio of GGBFS above the compressive strength equivalent to OPC was higher under low temperature conditions. The use of GGBFS resulted in high shrinkage compared to OPC, and this characteristic was even greater under low temperature conditions. The shrinkage of specimen with EA was decreased in early ages, but was higher than the OPC in long-term ages.