• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.41-42
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• 2006

Carbon nanotubes (CNTs) effects on physical properties of the liquid crystal and twisted nematic (TN) liquid crystal (LC) cells have been investigated. The minute doping of CNTs reduces rotational viscosity of the LC, and thus switching time of the TN cells is improved, especially in grey scale response time. In addition, the dielectric anisotropy and birefringence are not affected by such a small amount of CNT-doping and thus voltage-dependent transmittance remains the same.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.69-72
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• 2005

In this study, effects of IHPs with various resting times to cell adhesion were investigated through the measurements of cell adhesive force, number and area of focal contacts (stained vinculin spots), and projected cell area, perimeter and circularity. In addition correlation tests and curve estimations using the experimental results were performed fur the finding an essential factor for increment of cell adhesive force. Tn the results, immediately after mechanical stimuli (150 minutes after seeding) and one hour later (210 minutes after seeding), the average adhesive force of experimental group 5 (resting time: 15min) compared with that of control group at same culture time was increased significantly (p<0.05). Average projected area and perimeter of cells at Group 5 were increased significantly (p<0.05), while average circularity of cells at Group 5 incubated fur 210 minutes was decreased significantly (p<0.05). In the digital image analysis of focal contacts containing vinculins, area and numbers of focal contacts per cell at Group 5 were higher than those of the other groups. This study indicated that IHP with appropriate resting time could contribute in improving cell adhesive force, cell spreading, development of cytoskeleton and formation of focal contacts. And cell adhesive force was correlated to the morphological aspects of cell and development of focal contacts. Particularly, area of focal contacts was closely related to cell adhesive force.

• Preventive Nutrition and Food Science
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• v.14 no.1
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• pp.21-28
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• 2009

In this study, we focused on natural water-soluble antioxidants from Tetraselmis suecica (T. suecica) and Chlorella ellipsoidea (C. ellipsoidea). They were prepared by enzymatic digestion using five carbohydrases (Viscozyme, Celluclast, AMG, Termamyl and Ultraflo) and five proteases (Protamex, Alcalase, Flavourzyme, Neutrase, and Kojizyme), and the potential antioxidant activity of each was assessed. Most enzymatic digests from T. suecica had a higher radical scavenging activity than those from C. ellipsoidea. Among the enzymatic digests, Kojizyme digest from T. suecica exhibited the highest effect on DPPH radical scavenging. Viscozyme (30.2%) and Neutrase (34.6%) digests from T. suecica exhibited higher hydroxyl radical scavenging activity. Kojizyme digest from T. suecica (81.5%) had strong alkyl radical scavenging activity. Neutrase (61.9%) and Kojizyme (61.5%) digest from T. suecica possessed the highest effects on hydrogen peroxide scavenging. Among the tested samples, Neutrase (TN) and Kojizyme (TK) digests from T. suecica showed the highest antioxidant activity (DPPH, alkyl radical, hydrogen peroxide). Therefore, TN and TK digests were selected for use in the further experiments. Those digests showed enhanced cell viability against $H_2O_2$-induced oxidative damage, and relatively good hydrogen peroxide scavenging activity in an African green monkey kidney (Vero) cell line. These results suggested that an enzymatic digestion will be an effective way for the production of a potential water-soluble antioxidant from a microalgae, T. suecica.

• Korean Journal of Microbiology
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• v.23 no.1
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• pp.9-12
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• 1985

As a part of the host cell development for a amplified recombinant trp operon, $aroP^-$ mutation was introduced in a E. coli host strain. $aroP^-$ mutation was induced by transposon Tn10 and transduced into the E. coli host cell by bacteriophage P1Kc. The effect of $aroP^-$ mutation on the excretion of tryptophan in E. coli $trpR^{-ts}/ColE_1 -trp^+$ cells was investigated. Mutant lacking the general aromatic transport system was resistant to ${\beta}-2-thienylalanine\;(2{\times}10^{-4}\;M)$, p-fluorophenylalanine $(2{\times}10^{-4}M)$, or 5-methyltryptophan $(2{\times}10^{-4}\;M.)[^3H]-tryptophan$ uptake of the $aroP^-$ mutant strain was reduced considerably as compared with $aroP^+$ counterpart. The rate of $[^3H]-tryptophan$ uptake of the $aroP^-$ mutant strain treated with $NaN_3(3{\times}10^{-2}\;M)$ was much less affected than that of $aroP^+$ counterpart. The $aroP^-$ transductants increased the tryptophan excretion from E. coli $trpR^{-ts}/ColE_1 -trp^+$ four times more than $aroP^+$ counterpart.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.737-744
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• 2007

Recently, one of the most interesting topic in the field of wastewater treatment is the disposal of excess sludge. The new concept of excess sludge reduction with recirculation of solubilized sludge via effective microorganisms for cell disruption within the wastewater treatment process has been developed in this study. The alkalophiles for degradation of sludge cell wall were isolated as Exiguobacterium sp., which could be more effectively solubilized sludge in the anaerobic condition. The SCOD of solubilized excess sludge by Exiguobacterium sp. was up to about 2,000mg/L and average TN and TP concentration of solubilized component were 117mg/L and 58mg/L, respectively and C/N ratio was more than 17. To investigate the effects of solubilized sludge by alkalophiles on excess sludge reduction and nutrient removal efficiency, the pilot plant of $DF^{(S)}-MBR$ process, combined with membrane bioreactor and sludge solubilization tank, was operated. In the control run(without sludge solubilization), the daily sludge production was about 4.54 kgMLVSS/day. However, in the $DF^{(S)}-MBR$(with sludge solubilization), the daily sludge production was decreased to 1.39kgMLVSS/day. The effluent quality satisfied the effluent regulation in both cases. Furthermore, the $DF^{(S)}-MBR$ showed relatively better TN removal efficiency in spite of high influent loading. So we concluded that the solubilized excess sludge by alkalophiles was effectively degraded in the MBR process as the carbon source and 70% of sludge reduction efficiency can be achieved.

• Journal of Korean Society on Water Environment
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• v.39 no.1
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• pp.20-29
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• 2023

This study analyzed the relationship between harmful cyanobacterial abundance and environmental factors in order to figure out the causes of the recent increase of cyanobacteria in Lake Dukdong from 2019 to 2021. Lake Dukdong, which is used as a drinking water source for Gyeongju City, has an algae alert system in place. Lake Dukdong has maintained good water quality, but algae alert level 1 (over 1,000 cells/mL) has been issued in recent years. As a result of Pearson correlation analysis (from May to Oct.), the cell density of Microcystis and Aphanizomenon, which form part of the most harmful cyanobacteria genus, were significantly positively correlated with the water temperature and water storage volume. T-test was performed to compare the data from 2016-2018 and 2019-2021 (from May to Oct.). The average density of harmful cyanobacteria cells increased about six-fold from 54 to 344 cells/mL. There were significant differences in water temperature, pH, total nitrogen (TN), total phosphorus (TP), TN/TP ratio, water storage volume, and cyanobacterial cell density. Water temperature increased from 19.2 to 22.8 ℃. TP concentration increased from 0.017 to 0.028 mg/L. The main cause of the recent increase of harmful cyanobacteria in Lake Dukdong is thought to be the increase in water temperature, TP concentration, and water storage volume from 2019 and 2021, resulting in more favorable conditions for cyanobacterial growth.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.2
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• pp.109-115
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• 2023

In this paper, we demonstrated the orientation characteristics of liquid crystals using UV-treated FSAM as alignment layer. Moreover we confirmed the FSAM properties before and after UV treatment on indium tin oxide (ITO) glass substrates using physicochemical analysis. The hydrophobic property of the FSAM surface is change to hydrophilic through UV treatment. After UV treatment the LC molecules also were uniformly and horizontally aligned on the FSAM surfaces and the pretilt angle was obviously changed 90° degrees to 0° degrees. EO characteristic of TN cell which was fabricated with UV-treated FSAM was faster response time compare to conventional PI layer. The FSAM before and after UV treatment has a superior application potential as the LC alignment layer for LCD, potentially replacing the conventional polyimide layer.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.12
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• pp.1071-1079
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• 2002

This paper reports a methodology and application lot calculating distribution of the director in a liquid crystal cell by a numerical technique. To calculate distribution of the director, we applied a three dimensional finite element method (FEM) and calculated the distributions of electric potential and director in the liquid crystal cell. We have considered the free-energy density in the bulk of liquid crystal cell and calculated the switching property by the Ericksen-Leslie equation and the Laplace equation. We have calculated the optical transmission with distribution of the director by Berreman's method and confirmed the threshold voltage and the response time.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.05a
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• pp.178-179
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• 2003

The testis is composed of four cell types like supporting cells, steroid-producing cells, connective tissue cells and germ cells. Apoptosis is a common phenomenon during spormatogenesis. Apoptosis of germ cells can also be induced by exposure to radiation. Previous studies have shown that most types of germ cells are rather radiosensitive while somatic cells in testis are much more radio-resistant. The somatic cells in testis are divided to mainly Sertoli and Leydig cells. Though somatic cells are more radio-resistant than germ cells, radiation can induce the impairment of their function. This damaged function of somatic cells may accelerates degeneration of germ cell indirectly. Tn the present study, we have examined the apoptotic effect of mouse testis and irradiation effect of steroidogenesis of Leydig cells after irradiation.

• Journal of Information Display
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• v.7 no.1
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• pp.7-11
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• 2006

In this paper, we report the fabrication of high quality polymer walls by using a monomer containing fluorine (F-monomer). Polymer walls with no phase retardation were fabricated by using photo-polymerization induced anisotropic phase separation of the mixture composed of liquid crystal (LC) and F-monomer. Thanks to the immiscibility of fluoride, we could form high quality polymer walls with no light leakage. We measured electro-optic characteristics of a twisted-nematic (TN) LC cell whose polymer walls were fabricated by using the F-monomer, and the measurements were compared with that fabricated by using the monomer without fluorine.