• Progress in Medical Physics
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• v.21 no.2
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• pp.209-217
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• 2010

Retinal prostheses are being developed to restore vision for the blind with retinal diseases such as retinitis pigmentosa (RP) or age-related macular degeneration (AMD). Since retinal prostheses depend upon electrical stimulation to control neural activity, optimal stimulation parameters for successful encoding of visual information are one of the most important requirements to enable visual perception. Therefore, in this paper, we focused on retinal ganglion cell (RGC) responses to different voltage stimulation parameters and compared threshold charge densities in normal and rd1 mice. For this purpose, we used in vitro preparation for the retina of normal and rd1 mice on micro-electrode arrays. When the neural network of rd1 mouse retinas is stimulated with voltage-controlled pulses, RGCs in degenerated retina also respond to voltage amplitude or voltage duration modulation as well in wild-type RGCs. But the temporal pattern of RGCs response is very different; in wild-type RGCs, single peak within 100 ms appears while in RGCs in degenerated retina multiple peaks (~4 peaks) with ~10 Hz rhythm within 400 ms appear. The thresholds for electrical activation of RGCs are overall more elevated in rd1 mouse retinas compared to wild-type mouse retinas: The thresholds for activation of RGCs in rd1 mouse retinas were on average two times higher ($70.50{\sim}99.87\;{\mu}C/cm^2$ vs. $37.23{\sim}61.65\;{\mu}C/cm^2$) in the experiment of voltage amplitude modulation and five times higher ($120.5{\sim}170.6\;{\mu}C/cm^2$ vs. $22.69{\sim}37.57\;{\mu}C/cm^2$) in the experiment of voltage duration modulation than those in wild-type mouse retinas. This is compatible with the findings from human studies that the currents required for evoking visual percepts in RP patients is much higher than those needed in healthy individuals. These results will be used as a guideline for optimal stimulation parameters for upcoming Korean-type retinal prosthesis.

• KSBB Journal
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• v.15 no.2
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• pp.125-133
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• 2000

Specific carotenoids and astaxanthin biosynthesis power of Phaffia rhodozyma mutant 876, which was obtained after NTG a and UV treatments, was higher than those of the wild type by 40% and 50%, respectively. The mutant strain did not show t the catabolite repression even at 22% (w/v) glucose concentration. The optimum C{N ratio was 2.0, and the optimum t temperature and initial pH were $22^{\circ}C$ and 6.0, respectively. 80th cell growth and astaxanthin formation decreased drastically a as the fermentation temperature was increased over $22^{\circ}C$, whereas they were comparable in the pH range between 5.0 and 7 7.0. Inoculum size did not affect the final cell density nor the carotenoids biosynthesis, and 3%(v/v) was selected as optimal. H Higher dissolved oxygen concentration facilitated astaxanthin biosynthesis, and aeration rate of 1.0 v/0/m and agitation speed of 400 rpm were selected as optimum. The final cell dens때 of 43.3 g/L and the volumetric astaxanthin and carotenoids concentrations of 110.6 mg/L and 149.4 mg/L, respectively, were obtained. The specific carotenoids concentration was 3.45 m mg{g-yeast(dry). Yx/s and Yp/s values of 0.37 and 1.08 were obtained. The result of this study will provide basic information u useful for mass production of astaxanthin from P. rhodozyma fermentation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.212-216
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• 1981

The growth of Lactobacillus bulgaricus treated with vanillin, ortho-vanillin and guaiaco1 was studied on synthetic medium in mechanically agitated chemostat culture, The exponential-phase growth rate exhibited a maximum at the cells treated with 50 ppm vanillin. That stimulation, however, appears to be an effect on growth rate rather than total cell growth. And the others were inhibited by the chemicals. Much greater inhibition in growth of the cells treated with 100 ppm of each chemical than oars treated with 50 ppm was observed after 25 hour fomentation. For aerobic microbes, the alcohol dehydrogenase reaction is enhanced for the reproduction of NAD, which consequently cause to stimulate fermentation. For micro-aerophilic microbes , however, the same effect was not observed at the present study at least in the case of cell concentration. However except f or one treated with 50 ppm vanillin the same effect was observed in the case of growth is to. From the result using the glucose as a substrate, it was found that the cell concentrations measured in terms of ultimate optical density (UOB/ml), were 0.96 and 0.92, when treated with 50 and 100 ppm vanillin; 0.40 and 0.45 when treated with ortho-vanillin 50 and 100 ppm: 0.49 and 0.47, when treated with guaiacol 50 and 100 ppm. The specific growth rates were 0.44, 0.15, 0.25, 0.29, 0.37, and 0.34; the specific production rates wire 0.33, 0.15, 0.16, 0.22, 0.28, and 0.26 and the glucose concentrations (g/1) after 25 hour fermentation were 23.5, 32.8, 31.5, 29.5, 28.0 and 28.8, these all in the same sequences as the first.

• Korean Journal of Microbiology
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• v.46 no.3
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• pp.240-247
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• 2010

Pseudomonas aeruginosa is a Gram (-) opportunistic human pathogen causing a wide variety of infections on lung, urinary tract, eyes, and burn wound sites and quorum sensing (QS), a cell density-sensing mechanism plays an essential role in Pseudomonas pathogenesis. In order to investigate the importance of QS in the Pseudomonas infections of Korean patients, we isolated 189 clinical strains of P. aeruginosa from the patients in Pusan Paik Hospital, Busan, South Korea. The QS signal production of these clinical isolates was measured by signal diffusion assay on solid media using reporter strains. While most clinical strains (79.4%) produced the QS signals as similar level as a wild type strain, PAO1 did, where LasR, the initial QS signal sensor-regulator was fully activated, a minority of them (4.2%) produced much less QS signals at the level to which LasR failed to respond. Similarly, while 72.5% of the clinical isolates produced QS signals enough to activate QscR, an another QS signal sensor-regulator, some few of them (9%) produced the QS signals at much lower level where QscR was not activated. For further analysis, we selected 74 clinical strains that were obtained from the patients under suspicion of Pseudomonas infection and investigated the total protease activity that is considered important for virulence. Interestingly, significant portion of them showed very low protease activity (44.6%) or no detectable protease activity (12.2%). When the biofilm-forming ability that is considered very important in chronic infection was examined, most isolates showed lower biofilm-forming activity than PAO1. Similarly, significant portion of clinical isolates showed reduced motility (reduced swarming activity in 51.4% and reduced twitching activity in 41.9%), or non-detectable motility (swarming-negative in 28.4% and twitching-negative in 28.4%). Our result showed that the clinical isolates that produced QS signals at the similar level to wild type could have significantly reduced activities in the protease production, biofilm formation, and motility, and some clinical isolates had unique patterns of motility, biofilm formation, and protease production that are not correlated to their QS activity.

• Korean Journal of Korean Medical Institute of Dermatology and Aesthetics
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• v.1 no.1
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• pp.127-144
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• 2005

This study compared the activity of the aerial part of P. japonicum with its root in order to examine the possibility of the medicinal use of the aerial part, which has not been used as medicine, in substitute for the root that has traditionally been used as medicine. For this purpose, the author measured the proliferation of Human $CD4^-$ T cells, which are related to immunity, the differentiation of HL-60 cells, and the contents of IL-6, IgE and $TNF-{\alpha}$ and compared their anti-cancer effect on Hep3B and A549 cells. The results of this study are as follows: 1. As for Human $CD4^-$ T cells, $1.0\;g/{\ell}$ methanol extract from the aerial part promoted the proliferation of the cells 1.8 times higher while $1.0\;g/{\ell}$ methanol extract from the root did by 1.76 times higher compared to the control group. 2. As for HL-60 cells, methanol extract and water extract from the aerial part showed differentiation 1.14 times higher and 1.12 times higher respectively while methanol extract and water extract from the root did 1.14 times higher and 1.07 times higher compared to tile control group. 3. Cell density was highest on Day 4 of culture in all samples, Methanol extracts from the aerial part and the root showed activities of $7.9{\times}10^3\;cells/m{\ell}$ and $7.5{\times}10^3\;cells/m{\ell}$ respectively, and water extracts from the aerial part and the root did activities of $5.3{\times}10^3\;cells/m{\ell}$ and $6.1{\times}10^3\;cells/m{\ell}$. 4. The secretion of IL-6 was highest on Day 4 of culture. Methanol extracts from the aerial part and the root showed secretions of $6.7{\times}10^{-3}\;pg/cells/m{\ell}$ and $7.2{\times}10^{-3}\;pg/cells/m{\ell}$ respectively, and water extracts from the aerial part and the root did secretions of as high as $7.0{\times}10^{-3}\;pg/cells/m{\ell}$ and $6.0{\times}10^{-3}\;pg/cells/m{\ell}$. 5. As for the production of IgE, water extract from the root effectively inhibited the product at $1,000\;{\mu}g/m{\ell}$, methanol extract from the root at $10\;{\mu}g/m{\ell}$ and $100\;{\mu}g/m{\ell}$, water extract from the aerial at $1,000\;{\mu}g/m{\ell}$, and methanol extract from the aerial part at $1,000\;{\mu}g/m{\ell}$. 6. According to the result of measuring the content of $TNF-{\alpha}$, methanol extracts from the root and the aerial part showed inhibition effect at $10\;{\mu}g/m{\ell}$, $100\;{\mu}g/m{\ell}$ and $1,000\;{\mu}g/m{\ell}$. 7. As for liver cancer cell Hep3B, $1.0\;g/{\ell}$ methanol extracts from the root and the aerial part showed inhibition effects of 78% and 70% respectively, and $1.0\;g/{\ell}$ water extracts from the root and the aerial part did inhibition effects of 56% and 59%. 8. As for lung cancer cell A549, $1.0\;g/{\ell}$ methanol extracts from the root and the aerial part showed inhibition effects of 75% and 70% respectively, and $1.0\;g/{\ell}$ water extracts from the root and the aerial part did inhibition effects of 48% and 45%. The results of this study presented above show that the aerial part of P. japonicum has immunizing and anti-cancer effects as high as its root, which has commonly been used as medicine. There should be more in-depth research on the aerial part of P. japonicum in the future.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.868-873
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• 2019

In this study, the evaluation of performance of AORFB using methyl viologen and TEMPOL as organic active materials in neutral supporting electrolyte (NaCl) with various membrane types was performed. Using methyl viologen and TEMPOL as active materials in neutral electrolyte solution, the cell voltage is 1.37V which is relatively high value for AORFB. Two types of membranes were examined for performance comparison. First, when using Nafion 117 membrane which is commercial cation exchange membrane, only the charge process occurred in the first cycle and the single cell couldn't work because of its high resistance. However, when using Fumasep anion exchange membrane (FAA-3-50) instead of Nafion 117 membrane, the result was obtained as the totally different charge-discharge graphs. When current density was $40mA{\cdot}cm^{-2}$ and cut off voltage range was from 0.55 V to 1.7 V, the charge efficiency (CE) was 97% and voltage efficiency (VE) was 78%. In addition, the discharge capacity was $1.44Ah{\cdot}L^{-1}$ which was 54% of theoretical capacity ($2.68Ah{\cdot}L^{-1}$) at $10^{th}$ cycle and the capacity loss rate was $0.0015Ah{\cdot}L^{-1}$ per cycle during 50 cycles. Through cyclic voltammetry test, it seems that this difference in the performance between the full cell using Nafion 117 membrane and Fumasep anion exchange membrane came from increasing resistance due to chemical reaction between membrane and active material, not the capacity loss due to cross-over of active material through membrane.

• Tuberculosis and Respiratory Diseases
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• v.40 no.3
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• pp.213-222
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• 1993

Background : Bronchial asthma has been known as an inflmmatory disease. There have been many evidences that polymorphonuclear leukocytes (PMN) might play an important role in the pathogrnesis of asthma. Although many investigators suggested that pneumocyte injury by PMN-derived oxygen radicals may contribute to the pathogenesis of asthma, there has been few report for a direct evidence of oxygen radicals-mediated pneumocyte injury in bronchial asthma. Furthermore the exact mechanism of oxygen radicals-mediated pneumocyte injury is still controversy. This study was designed to establish a direct in vitro evidence and its clinical significance of pneumocyte injury by PMN-derived superoxide anion in bronchial asthma and to elucidate the main mechanism of superoxide anion-mediated pneumocyte injury. Methods : 12 stable asthmatics and 5 healthy volunteers were participated in this study. PMN was separated from peripheral venous blood samples by using dextran sedimentation and Ficoll-Hypaque density gradient separation method. Superoxide anion productions by PMN and plasma SOD activities were measured by spectrophotometric assay using the principle of SOD inhibitable cytochrome c reduction. PMN-mediated pneumocyte injuries were measured by $^{51}Cr$-release assay using A549 pneumocytes and were expressed as percent lysis and percent detachment. Results: 1) PMN from asthmatics produced more amount of superoxide anion compared to PMN from normal subjects ($6.65{\pm}0.58$ vs $2.81{\pm}0.95\;nmol/1{\times}10^6$ cells, p<0.05), and showed an inverse correlation with $FEV_1$(R=-0.63, p<0.05), but no correlation with $PC_{20}$ histamine in asthmatics. 2) Plasma SOD activities were decreased in asthmatics compared to normal subjects but not significant, and showed a positive correlation with $FEV_1$(R=0.63, p<0.05) but no correlation with $PC_{20}$ histamine in asthmatics. 3) There were a positive correlation between plasma SOD activity and superoxide anion production by PMN in normal subjects (R=0.88, p<0.05) but not in asthmatics. 4) PMN-mediated pneumocyte injury was predominantly expressed as cell detachment rather than cell lysis in both groups, and PMN from asthmatics showed more potent cytotoxic effect on A549 pneumocytes compated to PMN from normal subjects. PMN-mediated detachment rather than lysis of A549 pneumocytes was significantly inhibited by in vitro SOD but not by diluted serum. 5) PMN-mediated detachment rather than lysis of A549 pneumocytes showed a good correlation with superoxide anion production by PMN (R=0.90 in normal subjects, R=0.82 in asthmatics, p<0.05) but no correlation with plasma SOD activity. PMN-mediated pneumocyte injuries were not correlated with $FEV_1$ or $PC_{20}$ histamine in asthmatics. 6) There were no significant differences in PMN-mediated pneumocyte injuries between allergic and nonallergic asthmatics. Conclusion : Our results suggest that pneumocyte injury by PMN-derived superoxide anion may partially contribute to the pathogenesis of asthma and that cell detachment rather than cell lysis may be the mechanism of superoxide anion-mediated pneumocyte injury.

• Food Science and Preservation
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• v.22 no.2
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• pp.251-255
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• 2015

To optimize the medium composition of Undaria pinnatifida as a pH modulator the growth of Lactobacillus plantarum industrial scale, we analyzed the pH and growth characteristics of L. plantarum in basal medium. Subsequently, the medium compositions addition of carbon, nitrogen sources and buffering agents were optimized. When 0.5% yeast extract and 2% glucose, L. plantarum grew to maximum cell density in experimental condition. However, the growth of L. plantarum rapidly pH 4.0 in basal medium. A high alkali-ash value and low cost-effective utilization n the waste part as examined. ddition of U. pinnatifida extract alleviated the serious decrease. Among them, juice of U. pinnatifida was most helpful for the growth of L. plantarum ($36.3{\pm}1.810^8CFU/mL$). These results show that U. pinnatifida be large-scale cultivation of L. plantarum. This optimized U. pinnatifida medium can be used for safe and economical production of Lactobacillus.

• Solar Energy
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• v.10 no.3
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• pp.60-65
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• 1990

[ $n^+-p^+$ ] InP homojunction solar cells were fabricated by thermal diffusion of sulphur into a $p^+$-InP wafer($p=4{\times}10^{18}cm^{-3}$), and a SiO film($600{\AA}$ thick) was coated on the $n^+$ layer as an antireflection(AR) coating by an e-beam evaporator. The volume of the cells were $5{\times}5{\times}0.3mm^3$. The front contact grids of the cells with 16 finger pattern of which width and space were $20{\mu}m$ and $300{\mu}m$ respectively, were formed by photo-lithography technique. The junction depth of sulphur were as shallow as about 0.4r m We found out the fabricated solar cells that, with increasing the diffusion time, short circuit current densities($J_{sc}$), series resistances($R_s$) and energy conversion efficiencies(${\eta}$) were increased. The cells show good spectral responses in the region of $5,000-9,000{\AA}$. The short circuit current density, the open circuit voltage( $V_{oc}$), the fill factor(F.F) and the energy conversion efficiency of the cell were $13.16mA/cm^2$, 0.38V, 53.74% and 10.1% respectively.

• International Journal of Highway Engineering
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• v.10 no.1
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• pp.87-95
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• 2008

One way to shield an atypical structure to secure the occupant safety of an impact vehicle is to stack energy absorbing material modules around the structure. To be applicable to a cushion module, material must have enough energy absorbing capabilities while satisfying the safety requirements of the vehicle occupant. Static compression test of the potential materials gives a good indication which material is good for a slacking module. This paper presents the mechanical properties that a cushion material must have to satisfy the safety requirements. Static tests are performed for Quard-Guard system module, sand bag, recycled tires, Geo-Container, Geo-Cell and Expanded Polystyren (EPS) Blocks. Static test results are discussed and EPS block of $30kg/m^{3}$ density showed good potential for a cushion module. To check the dynamic effect of EPS block, drop tests have been made up to 35.6km/h impact speed. Drop test results are compared with static test results and no appreciable difference was found. To improve the EPS module property, making holes to the block is suggested and drop test are performed for the modified blocks. From the drop test results, design values are suggested.