• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.1
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• pp.71-82
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• 1996

In this paper, the Doppler phase error due to the relative velocity between a satellite and the earth station in communications using a low earth orbit mobile satellite is detected. The performance of BPSK system in the presence of Rician fading with Doppler phase error and interference, noise is compared with that of the system disturbed by Doppler phase error and noise only. The expression of error rate performance of BPSK system is derived as the type of complementary error function. The numerical calculation of the induced equation are performed in terms of satellite-height, orbit-eccentricity, the velocity of the earth, Rician fading parameter, signal to interference rateio (SIR), the ratio of carrier frequency and base band bit rate. The main conclusion that can be drawn from this analysis is that Rician fading channel environment with Doppler phase error and interference effect yields severe performance degradation than Do- ppler phase error and noise effect in satellite communication channel. And using the numerical calculation, we give a quantitative insight how much the satellite communication channel parameters degrade the system performance. Furthermore it is shown that an appropriate transmission power control for the performance enhancement is beneficial to the new satellite communication system planning.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.2
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• pp.128-138
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• 1996

In this paper, the Doppler phase error due to the relative velocity between a satellite and the earth station in communications using a low earth orbit mobile satellite is detected. The performance of BPSK system in the presence of Rician fading channel environment with Doppler phase error, inter- ference and noise is compared with that of the system disturbed by Doppler phase error and noise only, And adopted coding techniques are Hamming, BCH, RS and convolution codes. The expression of error rate performance of BPSK system is derived as the type of complementary error function. The main conclusion that can be drawn from this analysis is that Rician fading channel environment with Do- ppler phase error and interference, noise effect yields severe performance degradation then Doppler phase error and noise effect in satellite communication channel. The conclusion can be drawn from this analysis is that using coding technique then noncoding. And using the numerical calculation, we give a quantitative insight how much the satellite communication channel parameters degrade the system per- formance. Furthermore it is shown that an appropriate transmission power control for the performance enhancement is beneficial to the new satellite communication system planning.

• Biomolecules & Therapeutics
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• v.24 no.5
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• pp.543-551
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• 2016

This study was designed to evaluate the pharmacological effects of Vaccinium bracteatum Thunb. methanol extract (VBME) on microglial activation and to identify the underlying mechanisms of action of these effects. The anti-inflammatory properties of VBME were studied using lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. We measured the production of nitric oxide (NO), inducible NO synthase (iNOS), cyclooxygenase (COX)-2, prostaglandin $E_2$ ($PGE_2$), tumor necrosis factor-alpha (TNF-${\alpha}$), interleukin-1 beta (IL-$1{\beta}$), and interleukin-6 (IL-6) as inflammatory parameters. We also examined the effect of VBME on intracellular reactive oxygen species (ROS) production and the activity of nuclear factor-kappa B p65 (NF-${\kappa}B$ p65). VBME significantly inhibited LPS-induced production of NO and $PGE_2$ and LPS-mediated upregulation of iNOS and COX-2 expression in a dose-dependent manner; importantly, VBME was not cytotoxic. VBME also significantly reduced the generation of the pro-inflammatory cytokines TNF-${\alpha}$, IL-$1{\beta}$, and IL-6. In addition, VBME significantly dampened intracellular ROS production and suppressed NF-${\kappa}B$ p65 translocation by blocking $I{\kappa}B-{\alpha}$ phosphorylation and degradation in LPS-stimulated BV2 cells. Our findings indicate that VBME inhibits the production of inflammatory mediators in BV-2 microglial cells by suppressing NF-${\kappa}B$ signaling. Thus, VBME may be useful in the treatment of neurodegenerative diseases due to its ability to inhibit inflammatory mediator production in activated BV-2 microglial cells.

• Korean Journal of Environmental Biology
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• v.31 no.3
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• pp.180-188
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• 2013

The objectives of the study were to analyze chemical water quality and fish community structures in the downstreams of Geum River during 2004~2005. Water quality parameters showed that ionic dilution was evident during July~August due to a rainfall and river runoff by Asian monsoon. Mean concentrations of BOD showed a seasonal variation and were greater in the downstream than in the midstream. The total number of fish species observed was 34 (11 families) and 30.3% of them was Korean endemic species. The dominant species with > 20% of the total were Zacco platypus (25.9%) and Microphysogobio jeoni (21.5%) in the river. Exotic species observed was only one species, Carassius cuvieri with relative abundance of 1.8%. According to the structure analysis of fish community, species richness index was highest (3.714) in S6 and lowest in S4 (1.961), while species diversity index was highest in S2 (1.01) and lowest in S5 (0.507). Tolerant species dominated the fish community (49%), and the sensitive species were rare (4.4%), indicating a biological degradation of ecosystem. In the mean time, omnivore species was composed of 49% in the fish community and insectivore species was nearly same with the proportion of the omnivores.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.559-566
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• 2012

In this study, fiber elements and a spring are used to build a reinforced concrete shear wall model. The fiber elements and the spring reflect flexural and shear behaviors of the shear wall, respectively. The fiber elements are built by inputting section data and material properties. The spring parameters representing strength and stiffness degradation, pinching, and slip were determined by comparing behaviors of fiber element and VecTor2 results. 'Pinching4' model in OpenSees is used for shear spring. The parameter selecting process for shear spring is a complicated and time consuming process. To study the applicability of the fiber element, reinforced concrete buildings containing a shear wall are evaluated using nonlinear dynamic analysis with various wall aspect ratio (H/L), various beam heights, and stiffness and flexural strength of beam and wall ratios. The aspect ratio of the wall showed distinct difference in IDR (interstory drift ratio) of the models with and without spring. On the other hand, the height of beam and ratio of stiffness and flexural strength of beam and wall did not show clear relation.

• Korean Journal of Microbiology
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• v.45 no.1
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• pp.32-40
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• 2009

To understand contribution of thermophilic microorganisms in decomposition of litter deposits on shore of lakes, we surveyed a lakeshore litter deposit for bacteria growing at $60^{\circ}C$. Ten thermophilic isolates were selected for in-depth characterization, based on their high capacity to degrade high molecular weight organic compounds. Based on phylogenetic analysis on their 16S rRNA gene sequences, all isolates were identified as Geobacillus. The optimal growth temperature and pH of the strains ranged $55{\sim}60^{\circ}C$ and 6.0${\sim}$8.0, respectively. Salinity was inhibitory to the growth of the isolates, showing marked decrease of growth rates at 3% salinity. Based on activities of hydrolytic enzymes and profiles of carbohydrate utilization (determined by API 50 CHB kit), three G. stearothermophilus strains showed patterns clearly distinctive from other isolates. Two G. kaustophilus strains also demonstrated distinctiveness in their metabolic pattern and ecological parameters. However, ecological and metabolic profiles of the other five isolates were more variable and showed some degree of digression from their phylogenetic classification. Therefore, it could be concluded that endospore-forming thermophilic bacteria in lakeshore litter deposits contribute to degradation of organic materials with diverse ecological niches while having successions similar to microbial flora in compost. We propose that the thermophilic isolates and/or their thermo-tolerant enzymes can be applied to industrial processes as appropriate mixtures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.58-65
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• 2016

This study was a preparatory experiment aimed the development of membrane scaffolds for tissue engineering. A PCL composite solution contained sodium chloride(NaCl). PCL porous membrane scaffolds were formed on a glass casting plate using a film applicator and immersed in distilled water to remove the NaCl reaching after drying. NaCl was used as a pore former for a 3 dimensional pore net-work. The dry condition parameters were $4^{\circ}C$, room temperature (RT) and $40^{\circ}C$ for each different temperatures in the drying experiment. SEM revealed the morphology of the pores in the membrane after drying and evaluated the in vitro cytotoxicity for basic bio-compatibility. The macro and micro pores existed together in the scaffold and showed a 3-dimensional pore net-working morphology at RT. The in vitro cytotoxicity test result was "grade 2" in accordance with the criterion for cytotoxicity by ISO 10993-5. The dry condition affected the formation of a 3 dimensional pore network and micro and macro pores. Therefore, these results are expected provide the basic process for the development of porous membrane scaffolds to control degradation and allow drug delivery.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.228-236
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• 2008

The purpose of this study was to evaluate fish metric attributes using a model of Lentic Ecosystem Health Assessment (LEHA) and apply the model to the dataset sampled from six sites of Namyang Reservoir during October 2005$\sim$May 2006. The model was composed of 11 metries and the metric attributes were made of physical, chemical and biological parameters. Trophic composition's metrics showed that tolerant species ($M_3$, 80%) and omnivore species ($M_4$, 92%) dominated the fish fauna, indicating a biological degradation in the aquatic ecosystem. The metric of $M_7$, relative proportions of exotic species, also showed greater than 8% of the total, indicating a ecological disturbance. The average value of LEHA model was 24.3 (n= 12) in the reservoir, indicating a "poor condition" by the criteria of An and Han (2007). Spatial variation based on the model values was low (range: $21{\sim}26$), and temporal variation occurred due to a monsoon rainfall. Electrical conductivity (EC) and tropic state index of chlorophyll-$\alpha$ [TSI(CHL)] was greater in the premonsoon than the postmonsoon.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.2
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• pp.41-54
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• 1999

Because of relatively heavy dead weight of concrete itself and unavoidable heat of massive concrete in bridge piers, circular hollow columns are widely used in Korean highway bridges. Since the occurrence of 1995 Kobe earthquake, there have been much concerns about seismic design for various infrastructures, inclusive of bridge structures. It is, however, understood that there are not much research works for nonlinear behavior of circular hollow columns subjected to eqrthquake motions. The objective of this experimental research is to investigate nonlinear behavior of circular hollow reinforced concrete bridge piers under the quasi-static cyclic load, and then to enhance their ductility by strengthening the plastic hinge region with glassfiber sheets. Particularly for this test, constant 10 cyclic loads have been repeatedly actuated to investigate the magnitude of strength degradation for the displacement ductility factor. Important test parameters are seismic design, confinement steel ratio, axial force and load pattern. It is observed from quasi-static tests for 7 bridge piers that the seismically designed columns and the retrofitted columns show better performance than the nonseismically designed colums, i.e. about 20% higher for energy dissipation capacity and about 70% higher for curvatures.

• Korean Journal of Poultry Science
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• v.43 no.4
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• pp.213-218
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• 2016

This study was conducted to investigate the effect of taurine supplementation on heat shock protein 70 and in vitro protein turnover in broiler chicks under chronic heat stress. Chicks were allocated into 3 groups of 10 birds per group; the control group was maintained at a temperature of $24^{\circ}C$ without taurine (CO group), the heat-stressed group maintained at a temperature of $34^{\circ}C$ without taurine (HO group), and heat-stressed group maintained at a temperature of $34^{\circ}C$ with taurine (HT group). The final body and liver weights of broilers in the HO and HT groups were significantly lower than those of broilers in the CO group (P<0.05). However, these parameters of the broilers in the HT group were significantly higher than those of broilers in the HO group (P<0.05). The heat shock protein 70 (hsp70) concentration in the liver of broilers in the HO group was significantly higher than that of broilers in the CO and HT groups, but the hsp70 concentration in the liver of broilers in the HT group was not different from that of broilers in the CO group. Liver homogenates of 21 day-old broilers were incubated at temperatures of $37^{\circ}C$ and $45^{\circ}C$ to prove the effect of high temperature and taurine on total protein syntheses. Neither high temperature nor taurine supplementation affected protein syntheses in liver homogenates of the broilers. However, the more the temperature increased, the more the degradation rates of cytoplasmic protein in liver homogenates increased; however, taurine supplementation had no effects on the protein syntheses in the liver of the broiler. It is possible that taurine indirectly affected protein turnover via various physiological mechanisms.