• Journal of Biomedical Engineering Research
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• v.15 no.4
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• pp.383-388
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• 1994

Chaotic analysis of EEG signal responding to auditory stimulus with various carrier frequency and constant triggering frequency is given in this paper. The EEG signal is obtained from the digital 12channel EEG system made in our laboratory. The carrier frequency is varied from 1 kHz to 3 kHz by 0.5 kHz step. Chaos analysis such as pseudo phase space portrait, Lyapunov exponent, and so on is done on the auditory stimulated evoked potential. This result is found to be quite consistent with the well known results from the psychological perception theory.

• Membrane and Water Treatment
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• v.6 no.1
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• pp.1-13
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• 2015

The modification of ultrafiltration membranes with carbon nanotube (CNT) buckypaper on fouling control was investigated. Two types of commercially available flat-sheet membranes were used: PS35 and PES900C/D (PES) (the PS35 membranes were hydrophilic with a molecular weight cutoff of 20 kDa, and the PES membranes were hydrophobic with a molecular weight cutoff of 20 kDa). The CNT buckypaper modified ultrafiltration membranes were prepared by filtering a CNT suspension through the flat-sheet membrane in a dead-end ultrafiltration unit. After modification, the pure water flux of PES was significantly increased, while the pure water flux of PS35 was decreased. The properties of the CNT modified membranes were also investigated. Considering the antifouling properties, pure water flux of the modified membrane, and the stability of CNT buckypaper layer on the membrane surface, ethanol solution with a concentration of 50 wt.%, multi-walled carbon nanotubes (MWCNTs) with a larger diameter (30-50 nm), and the CNT loading with $7.5g/m^2$ was selected. The CNT buckypaper on the surface of ultrafiltration membranes can trap the pollutants in sewage effluent and prevent them reaching the surface of virgin membranes. Water quality analysis showed that the effluent quality of the modified membrane was obviously improved. The removal efficiency of humic acid and protein-like matters by the modified membrane was significant. These results indicate the potential application of the CNT buckypaper layer modified membranes in the field of wastewater reclaim.

• Food Science and Preservation
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• v.31 no.3
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• pp.394-407
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• 2024

The poultry industry faces disposal difficulty in waste, but recent advancements in material science and sustainability have enabled the innovative transformation of waste into valuable resources. In this study, eggshell (EC) was added as a bio-filler to gum Arabic (GA) to fabricate a GA-EC bio-composite film. Bio-composites containing 0.5 g (GA-EC_0.5) and 1.0 g (GA-EC_1.0) EC dispersed in 30 mL of 15% GA solution were fabricated and characterized using standard analytical techniques. The GA-EC_0.5 composites showed significantly higher moisture content, transparency, water solubility, and water vapor permeability but lower tensile strength and thermal stability than GA-EC_1.0. Following a post-harvest wrapping of tomato fruits with the GA-EC composite films and storage at 25±2℃ for 20 days, significant (p>0.05) reductions in weight loss, pH, lycopene content, and activities of polyphenol oxidase and pectin methylesterase compared to unwrapped fruits were recorded. Adding EC to GA has enabled the fabrication of composite films with improved mechanical, barrier, and thermal properties with potential application in the post-harvest storage of tomato fruits.

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.640-644
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• 2008

Lubricating oil on aluminium surfaces was cleaned by a low temperature plasma process. Oxygen plasma mixed with argon was used, and process parameters were the mixing ratio of argon in oxygen, discharge power, and negative DC potential. The aluminium surfaces were analyzed with FTIR and EDX after the cleaning. It was found that almost all of the oil was eliminated in 20 min. if the oil was pure. Elimination efficiency was highly dependent on operational conditions of the process. The highest efficiency was obtained when treated at 300 W with oxygen plasma mixed with 30% argon applying negative potential more than -500 V on the aluminium surfaces. However, efficiency higher that 60% cannot be obtained at any condition if the oil contained inorganic materials.

• Korean Journal of Social Welfare
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• v.57 no.2
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• pp.297-320
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• 2005

This study was attempted to give aids in making 'the Disability Discrimination Act' by estimating the potential Cost-Benefit in case that the discrimination on the disabled is removed. The potential benefits from this Disability Discrimination Act are calculated considering the income increase of the people with disabilities from additional employment for them and the decrease of employment levies and the public assistance benefits. The potential cost was made focusing on the following 2 expenses- the extra expenditures that the owners of companies had to invest from the employment of the disabled and the managing expenses for correcting discrimination organizations. As the result of this estimation, the potential net present value under the 7% discount rate is very high as 12,700,301 million won and the cost-benefit ratio is also great as 96.8. The consequence of the sensitive analysis in changing the discount rate also does not have great changes. As the result of these estimating results, it is known that when the discrimination is solved by the 'Disability Discrimination Act', the pure benefit of our society will become tremendous. After all, it could be said that the need for 'the Disability Discrimination Act' is emphasized and should be emphasized.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.3
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• pp.311-319
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• 2018

Mitochondrial calcium overload is a crucial event in determining the fate of neuronal cell survival and death, implicated in pathogenesis of neurodegenerative diseases. One of the driving forces of calcium influx into mitochondria is mitochondria membrane potential (${\Delta}{\psi}_m$). Therefore, pharmacological manipulation of ${\Delta}{\psi}_m$ can be a promising strategy to prevent neuronal cell death against brain insults. Based on these issues, we investigated here whether nobiletin, a Citrus polymethoxylated flavone, prevents neurotoxic neuronal calcium overload and cell death via regulating basal ${\Delta}{\psi}_m$ against neuronal insult in primary cortical neurons and pure brain mitochondria isolated from rat cortices. Results demonstrated that nobiletin treatment significantly increased cell viability against glutamate toxicity ($100{\mu}M$, 20 min) in primary cortical neurons. Real-time imaging-based fluorometry data reveal that nobiletin evokes partial mitochondrial depolarization in these neurons. Nobiletin markedly attenuated mitochondrial calcium overload and reactive oxygen species (ROS) generation in glutamate ($100{\mu}M$)-stimulated cortical neurons and isolated pure mitochondria exposed to high concentration of $Ca^{2+}$ ($5{\mu}M$). Nobiletin-induced partial mitochondrial depolarization in intact neurons was confirmed in isolated brain mitochondria using a fluorescence microplate reader. Nobiletin effects on basal ${\Delta}{\psi}_m$ were completely abolished in $K^+-free$ medium on pure isolated mitochondria. Taken together, results demonstrate that $K^+$ influx into mitochondria is critically involved in partial mitochondrial depolarization-related neuroprotective effect of nobiletin. Nobiletin-induced mitochondrial $K^+$ influx is probably mediated, at least in part, by activation of mitochondrial $K^+$ channels. However, further detailed studies should be conducted to determine exact molecular targets of nobiletin in mitochondria.

• Journal of the Korean Electrochemical Society
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• v.6 no.2
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• pp.113-118
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• 2003

Processible polyaniline (PAM) dispersions consisting of polyaniline micro-particles, cyclohexanone, and a polymeric surfactant were prepared in a micro-milling machine with various mixing conditions. The electrochemical properties of the dispersion film coated on Pt electrode were investigated by cyclic voltammetry (CV). The electrochemistry of the PAM dispersion coatings was basically similar to a pure PAM coating based on the results of CV. The results of polarization measurements and open circuit potential measurements carried out in $3\;wt.\%$ NaCI solution showed increase in corrosion potential when the PANI dispersion coatings applied on steel surface. Variation of open circuit potential $(OCP,\;V_{OC})$ of the dispersion coating/steel electrodes was observed, which differed with milling conditions. The results demonstrated practical use of the conducting polymer dispersion as a coating material for corrosion prevention of steel.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.2
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• pp.300-308
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• 2004

The formation mechanism of anodic oxide films on Mg alloys when anodized in NaOH solution. was investigated by focusing on the effects of anodizing potential. Al content. and anodizing time. Pure Mg and Mg-Al alloys were anodized for 10 min at various potentials in NaOH solutions. $Mg(OH)_2$ was generated by an active dissolution reaction at the surface. and the product was affected by temperature. The intensity ratio of $Mg(OH)_2$ in the XRD analysis decreased with increasing applied potential. while that of MgO increased. The anti-corrosion properties of anodized specimens at each constant potential were better than those of non-anodized specimens. The specimen anodized at an applied potential of 3 V had the best anti-corrosion property. And the intensity ratio of $Mg_{17}Al_{12}$/Mg increased with aluminum content in Mg-Al alloys. During anodizing. the active dissolution reaction occurred preferentially in ${\beta}\;phase(Mg_{17}Al_{12})$ until about 4 mins. and then the current density increased radually until 7 mins. The dissolution reaction progressed in a phase(Mg) which not formed the intermetallic compound. which had a lower Al content. In the anodic polarization test of $0.017\;mol{\cdot}dm^-3$ NaCl and $0.1\;mol{\cdot}dm^-3\;Na_2SO_4$ at 298 K. the current density of Mg-15 mass% Al alloy anodized for 10 mins increased. since the anodic film that forms on the a phase is a non-compacted film. The anodic film on the phase for 30 mins was a compact film as compared with that for 10 mins.

• The Korean Journal of Physiology
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• v.20 no.2
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• pp.165-174
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• 1986

The voltage clamp studies were undertaken to elucidate the properties of the slow inward current, $i_{si}$, in the small preparations of the rabbit sinoatrial node. The slow inward current, $i_{si}$, which is known to be responsible for the late one-third of pacemaker potential and whole range of upstroke phase of action potential was analysed with the effects of isoprenaline, cobalt, ouabain and higenamine. The results obtained are as follows; 1) Voltage of SA node preparation was held at zero current level, usually-40mV and the slow inward current, $i_{si}$, was activated by depolarizing clamp pulses. Peak values of $i_{si}$, in steady state were at $-10{\pm}0mV$ in most preparations. 2) Isoprenaline, ${\beta}-agonist$ increased $i_{si}$ and no shift was noticed in voltage-dependency. 3) Cobalt ion in the concentration of 1 mM abolished is, in entire range of membrane potential and the difference of two current levels before and after $Co^{2+}$ treatment could be considered as pure $i_{si}$ magnitude. 4) In the therapeutic concentration of ouabain $(5{\times}10^{-8}M)$ slightly increased is, and reduced the time to reach the peak value. 5) Higenamine $(10^{-6}M)$ changed the configurations of action potential (i. e. rapid upstroke phase and notch in the spike) and increase spontaneous rate. It also increased is, and the effect of higenamine was blocked ${\beta}-blocker$, propranolol $(10^{-6}M)$.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.1
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• pp.40-48
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• 2017

In this study, we evaluated the nitrogen (N) mineralization potential and Nitrogen use efficiency (NUE) of oil-cake, compost, hairy vetch and barley, which are the most widely used organic amendments in South Korea. The N mineralization potential (No) for organic fertilizers treated soil was highest for the hairy vetch treatment with a value of $18.9mg\;N\;100\;g^{-1}$, followed by oil-cake, barley and compost. The amount of pure N mineralization potentials in hairy vetch, oil-cake, barley and compost treatments were 8.42, 7.62, 3.82 and $3.60mg\;N\;100\;g^{-1}$, respectively. The half-life ($t_{1/2}$) of organic N in soil amended with oil-cake fertilizer mineralized quickly in 17 days. While, $t_{1/2}$ values of organic N for the compost and barley treatments accounted to 44.4 and 44.1 days, respectively. Oil-cake was good in supplying nutrients to plants. Compost and barley inhibited plant growth in the beginning growth stage and this is attributed to N immobilization effect. The results of this study highlight that compost and barley could be used as potential slow release fertilizers in conventional agriculture.