• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.147-147
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• 2011

High crystalline nonpolar a-plane (11-20) nitride light emitting diodes (LEDs) have been fabricated on r-plane (1-102) sapphire substrates by metalorganic chemical-vapor deposition (MOCVD). The multi-quantum wells (MQWs) active region is consists of 4 periods the nonpolar a-plane InGaN/GaN(a-InGaN/GaN) on a high quality a-plane GaN (a-GaN) template grown by using the multibuffer layer technique. The full widths at half maximum (FWHMs) of x-ray rocking curve (XRC) obtained from phiscan of the specimen that was grown up to nonpolar a-plane GaN LED layers with double crystal x-ray diffraction. The FWHM values were decreased down to 477 arc sec for $0^{\circ}$ and 505 arc sec for $-90^{\circ}$, respectively. After fabricating a conventional lateral LED chip which size was $300{\times}600{\mu}m^2$, we measured the optical output power by on-wafer measurements. N-electrode was made with Cr/Au contact, and ITO on p-GaN was formed with Ohmic contact using Ni/Au followed by inductively coupled plasma etching for mesa isolation. The optical output power of 1.08 mW was obtained at drive current of 20 mA with the peak emission wavelength of 502 nm.

• Journal of Sensor Science and Technology
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• v.11 no.6
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• pp.358-364
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• 2002

In this paper, we used U.V.(wavelength, 355nm) laser for adjusting Pt thin films temperature sensor to $100{\Omega}$ at $0^{\circ}C$. Internationally, A-class tolerance of temperature sensor is $0.06{\Omega}$ at $0^{\circ}C$. This is under value of $0.15^{\circ}C$, actually, so high-fine trimming technology is essential to this process. The width of trimmed lines was about $10{\mu}m$ and the best trimming of Pt thin films of $1{\sim}1.5{\mu}m$ was carried out with power : 35mW, rep. rate frequency : 200Hz and bite size : $1.5{\mu}m$. And using photolithography process, 96 resistors were fabricated in $2"{\times}2"$ substrate as the proportion of $79{\sim}90{\Omega}$ and $91{\sim}102{\Omega}$ is 42.7% and 57.3%, respectively. As result of trimming resistors to the target value of $109.73{\Omega}$ at $25^{\circ}C$, 82.3% of resistors had the tolerance within ${\pm}0.30{\Omega}$ and the others(17.7%) were within ${\pm}0.06{\Omega}$ of A-class tolerance.

• Journal of Periodontal and Implant Science
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• v.41 no.2
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• pp.73-78
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• 2011

Purpose: For periodontal tissue engineering, it is a primary requisite and a challenge to select the optimum types of cells, properties of scaffold, and growth factor combination to reconstruct a specific tissue in its natural form and with the appropriate function. Owing to fundamental disadvantages associated with using a two-dimensional substrate, several methods of seeding cells into three-dimensional scaffolds have been reported and the authors have asserted its usefulness and effectiveness. In this study, we explore the cell attachment of periodontal ligament fibroblasts on nanohydroxyapatite (n-HA) scaffold using avidin biotin binding system (ABBS). Methods: Human periodontal ligament fibroblasts were isolated from the health tooth extracted for the purpose of orthodontic procedure. HA nanoparticles were prepared and $Ca(NO_3)_2-_4H_2O$ and $(OC_2H_5)_3P$ were selected as precursors of HA sol. The final scaffold was 8 mm in diameter and 3 mm in height disk with porosity value of 81.55%. $1{\times}10^5$ periodontal ligament fibroblasts were applied to each scaffold. The cells were seeded into scaffolds by static, agitating and ABBS seeding method. Results: The number of periodontal ligament fibroblasts attached was greater for ABBS seeding method than for static or agitating method (P<0.05). No meaningful difference has been observed among seeding methods with scanning electron microscopy images. However, increased strength of cell attachment of ABBS could be deduced from the high affinity between avidin and biotin ($Kd=10^{-15}\;M$). Conclusions: The high-affinity ABBS enhances the ability of periodontal ligament fibroblasts to attach to three-dimensionally constructed n-HA scaffold.

• Archives of Pharmacal Research
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• v.19 no.6
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• pp.480-485
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• 1996

Brain GABA transaminase is inactivated by preincubation with antidepressant/antipanic drug pheneizine (${\beta}$ethylphenylhydrazine) (mixing molar ratio 10:1) at pH 7.4. The reaction of enzyme with phenelzine was monitored by absorption and fluorescence spectroscopic methods. The inactive enzyme was fully reconstituted by addition of cofactor pyridoxal-5-phosphate. This result implies that the blocking of 1 mol of pyridoxal-5-phosphate per enzyme dimer is needed for inactivation of the enzyme. The time course of the reaction is significantly affected by the substrate .alpha.-ketoglutarate, which afforded complete protection against the loss of catalytic activity. The kinetic studies shows that phenelzine reacts with the cofactor of enzyme with a second-order rate constant of $2.1{\times}10^3M^{-1}s^{-1}$. It is postulated that the antidepressant/antipanic drug phenelzine is able to elevate the neurotransmitter GABA levels in central nervous system by inhibitory action on GABA degradative enzyme GABA transaminase.

• Journal of Life Science
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• v.19 no.11
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• pp.1623-1628
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• 2009

The purpose of this study was to investigate the effects of complex ergogenic aid supplementation on endurance performance, energy substrate utilization (glucose, FFA) and blood fatigue factors (ammonia, lactate, phosphorous, pH, 5-HT) in endurance exercise. Subjects (male=10) took in complex ergogenic aid (180 ml/day) for 4 weeks and were tested after pre-test. Endurance performance times increased after supplementation compared to before supplementation. However, there was no additional accumulation of the fatigue materials. Thus the complex ergogenic aid supplementation caused the delay of the fatigue material accumulation during endurance exercise.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.12
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• pp.1761-1768
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• 2006

In this study, the comparative effects of transgenic corn (Mon 810 and Event 176) and isogenic corn (DK729) were investigated for their influence on in vitro rumen fermentation. This study consisted of three treatments with 0.25 g rice straw, 0.25 g of corn (Mon810/Event176/DK 729) mixed with 30 ml rumen fluid-basal medium in a serum bottle. They were prepared in oxygen free conditions and incubated at $39^{\circ}C$ in a shaking incubator. The influence of transgenic corn on the number of bacterial population, F. succinogenes (cellulolytic) and S. bovis (amylolytic), was quantified using RT-PCR. Fermentative parameters were measured at 0, 2, 4, 8, 12 and 24 h and substrate digestibility was measured at 12 and 24 h. No significant differences were observed in digestibility of dry matter, NDF, ADF at 12 and 24 h for both transgenic and isogenic form of corns (p>0.05) as well as in fermentative parameters. Fluid pH remained unaffected by hybrid trait and decreased with VFA accumulation as incubation time progressed. No influence of corn trait itself was seen on concentration of total VFA, acetic, propionic, butyric and valeric acids. There were no significant differences (p<0.05) in total gas production, composition of gas (methane and hydrogen) at all times of sampling, as well as in NH3-N production. Bacterial quantification using RT-PCR showed that the population number was not affected by transgenic corn. From this study it is concluded that transgenic corn (Mon810 and Event 176) had no adverse effects on rumen fermentation and digestibility compared to isogenic corn. However, regular monitoring of these transgenic feeds is needed by present day researchers to enable consumers with the option to select their preferred food source for animal or human consumption.

• Journal of Life Science
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• v.23 no.6
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• pp.757-769
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• 2013

A microorganism producing carboxymethylcellulase (CMCase) was isolated from seawater, identified as Bacillus velezensis by analyses of 16S rDNA and partial sequences of the gyrA, and designated as B. velezensis A-68. The optimal conditions for production of CMCase by B. velezensis A-68 were established using response surface methodology (RSM). The optimal concentrations of rice hulls and yeast extract, and initial pH of the medium for cell growth were 60.2 g/l, 7.38 g/l, and 7.18, respectively, whereas those for production of CMCase were 50.0 g/l, 5.00 g/l, and 7.30. The analysis of variance (ANOVA) implied that the most significant factor for cell growth as well as production of CMCase was yeast extract. The optimal concentrations of $K_2HPO_4$, NaCl, $MgSO_4{\cdot}7H_2O$, and $(NH_4)_2SO_4$ in the medium for cell growth were 7.50, 1.00, 0.10, and 0.80 g/l, respectively, which were the same as those for production of CMCase. The optimal temperatures for cell growth and production of CMCase were 30 and $35^{\circ}C$, respectively. The maximal production of CMCase under optimized conditions was 83.8 U/ml, which was 3.3 times higher than that before optimization. In this study, rice hulls, agro-byproduct, were developed as a substrate for production of CMCase and time for production of CMCase was reduced to 3 days using a newly isolated marine bacterium.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.681-697
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• 1994

The enzymatic hydrolysate of gelatin extracted from fish skin was fractionated and recycled through the membrane reactor according to the molecular weight for the purpose of using as functional material. In addition, the enzymatic hydrolysis conditions of gelatin, enzyme stability by membrane and mechanical shear, and effect on the long-term operational stability of the recycle membrane reactor were investigated. Using the pH-drop technique, Alcalase, pronase E and collagenase were identified as the most suitable enzymes for the hydrolysis of fish skin gelatin. The optimum hydrolysis conditions in the 1st-step membrane reactor(1st-SMR) by Alcalase were enzyme concentration 0.2mg/ml, substrate-to-enzyme ratio(S/E) 50(w/w), $50^{\circ}C$, pH 8.0, reaction volume 600ml and flow rate 6.14ml/min. In the 2nd-SMR by pronase E were enzyme concentration 0.3mg/ml, S/E 33(w/w), $50^{\circ}C$, pH 8.0, reaction volume 600ml and flow rate 6.14ml/min. In the case of 3rd-SMR, enzyme concentration 0.1mg/ml, S/E 100(w/w), $37^{\circ}C$, pH 7.5, reaction volume 600ml and flow rate 10ml/min. Decreased enzyme activities by mechanical shear and membrane were 30% and 15% in the 1st-SMR, were 14% and 5% in the 2nd-SMR, and 18% and 8% in the 3rd-SMR, respectively. Under the optimum conditions, the degree of hydrolysis in the 1st, 2nd and 3rd-SMR were 3.5%(Kjeldahl method, 87%), 3.1%(77%) and 2.7%(70%), respectively. The productivity of hydrolysate in the continuous three-step membrane reactor was 430mg per enzyme(mg) for 10 times of volume replacements.

• Journal of Mushroom
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• v.5 no.1
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• pp.7-12
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• 2007

All intra-specific hybrids among ASI $2172{\times}2104$, $2172{\times}2307$, $2186{\times}2172$ and $2186{\times}2307$ in P. salmoneostramineus produced pink fruiting bodies as like wild parental types. However, three hybrids of them between ASI 2186 and 2104 were white fruiting bodies. A new commercial strain "Noeul" of Pink Oyster mushroom was developed by intra-specific hyphal anastomosis. It was improved with hybridization between monokaryotic strain derived from ASI 2172 and ASI 2104. The optimum temperature of mycelial growth and fruiting body development were $25{\sim}30^{\circ}C$ and $19{\sim}24^{\circ}C$, respectively. The pileus was bright reddish pink. Commercial strain "Noeul" was as prolific as the more commonly cultivated Pleurotus ostreatus in the conversion of substrate mass to mushrooms using bottle cultivation. Mushroom cultivator can save money for mushroom growing on summer in Korea. Mushrooms should be picked when moderately young, and handled carefully so as to not bruise the brilliantly colored gills. This pink color makes marketing an interesting challenge depending upon the market niche.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.12
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• pp.696-704
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• 2015

This study was carried out to evaluate the optimum operational condition of Semi-continuously Fed and Mixed Reactor (SCFMR) to treat the dairy cow manure and saw dust mixture. Step-wise increase in organic loading rates (OLRs) or decrease in hydraulic retention times (HRTs) were utilized until the biogas volume became significantly decreased at mesophilic temperature ($35^{\circ}C$). The optimum operating condition of the SCFMR fed with TS 13% dairy cow manure and saw dust mixture was found to be an HRTs of 25 days and its corresponding OLRs of $4.45kg\;VS/m^3-day$. At this condition the biogas and methane production rates were 1.44 v/v-d and 1.12 v/v-d (volume of biogas per volume of reactor per day), respectively and the TVS removal efficiency of 37% was achieved. The successful operation with such a high OLR was due to the high reactor alkalinity concentration of 14,500~15,600 mg/L as $CaCO_3$ as a result of the characteristic of the original substrate, dairy cow manure and saw dust mixture whose alkalinity was more than 8,000 mg/L as $CaCO_3$. The parameters for the reactor stability, the ratios of volatile acids and alkalinity concentrations (V/A) and the ratio of propionic acid and acetic acid concentrations (P/A) appeared to be 0.11 and 0.43, respectively, that were greatly stable in operation. Free ammonia toxicity was not experienced due to the long term acclimation by the reactor TS content ranged 7.2~10.4% during the entire operational period.