• Microbiology and Biotechnology Letters
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• v.20 no.4
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• pp.363-370
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• 1992

Microorganisms capable of accumulating poly-p-hydroxybutyric acid(PHB) were isolated from soil by enrichment culture technique. Among them, the strain designated as FL-027 had high PHB productivity and was identified as Alcaligenes. The optimal medium composition for cell growth was 8.0 $g/\ell$ of fructose and 3.0 $g/\ell$ of $(NH_4)_2S0_4$, equivalent to C/N ratio 5.04 at pH 7.0 and $30^{\circ}C$. To investigate the optimal conditions for the PHB accumulation, we divided the process into two stages; the first stage for the growth of the cell in nutrient-rich medium and the second stage for the PHB accumulation in nutrient-deficiency medium. The optimal conditions for PHB accumulation were 8.0 $g/\ell$ of fructose and 0.25 $g/\ell$ of $(NH_4)_2S0_4$, equivalent to C/N ratio 60 at pH 6.5 and $30^{\circ}C$. PHB accumulation was stimulated by deficiency of nutrients such as $NH_4^+$, $Ca^{2+}$, $SO_4^{2+}$ in medium. Among them. $NH_4^+$ deficiency was chosen because of its effectiveness. We found the inhibition of cell growth by fructose in batch culture. In order to keep the fructose concentration at an optimal level, intermittent feeding fed-batch culture was employed, and the cell concentration as high as 10.83 $g/\ell$ whose PHB content was responsible for 43% of the dry cell weight. The purified PHB was identified as homopolymer of 3-hydroxybutyric acid by using IR and $^1H-NMR$.

• Food Science of Animal Resources
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• v.32 no.6
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• pp.828-834
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• 2012

The present study has been conducted to investigate the effects of feeding seleniferous whole crop barley (WCB) to finishing pigs on their growth performance, blood and carcass characteristics as well as on tissue selenium deposition. A total of 40 cross-bred barrows ((Landrace${\times}$Yorkshire)${\times}$Duroc) were allotted to five replicates of four treatments. Each replicate was arranged to 2 pigs per pen; the experimental period lasted for 6 weeks. The finishing pigs were fed diets containing 0.1 (non-seleniferous WCB as a control), 0.2, 0.4 and 0.6 ppm of selenium (Se) by supplementing the diets with seleniferous WCB. The isonitrogenous and isocaloric diets containing 5% non-seleniferous or seleniferous WCB were formulated. Feeding seleniferous WCB did not affect (p<0.05) the feed intake and BW gain. Total blood lipid concentration was significantly (p<0.05) decreased with increasing Se levels. Total blood cholesterol concentration for the control was significantly (p<0.05) higher than that for 0.4 and 0.6 ppm of Se treatments. Increasing the Se levels in WCB significantly (p<0.05) decreased blood triglyceride concentration; however, the levels increased immunoglobulin G and selenium concentrations. Feeding seleniferous WCB did not affect the carcass rate, backfat thickness and meat quality as well as yield grades. The Se concentration in the kidney, liver and loin were significantly (p<0.05) increased with increasing levels of seleniferous WCB. The results indicated that feeding seleniferous WCB may improve the blood characteristics related to lipid metabolism and thus, could produce selenium-fortified pork. Moreover, it is shown that the dietary optimal selenium level to depose selenium in porcine tissues by utilizing seleniferous WCB would be 0.4 mg of Se/kg of ration. Moreover, when 100 g of pork produced from pigs raised under such condition is served to consumers, it meets the minimum recommended daily requirements (40 ${\mu}g$) of dietary selenium proposed by the World Health Organization (1996).

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.105.1-105.1
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• 2010

Korea Electric Power Research Institute (KEPRI) has developed a compact coal-gasification system to accumulate our experiment skills. The combustion furnace for residual oil was modified as a small size coal gasifier. Recently, coal feeding system was also upgraded to control coal feed rate more accurately. Our research group has conducted several experiments to find out the effect of $O_2$/coal ratio on the cold gas efficiency. Furthermore, the effect of $N_2$/coal ratio on the transport characteristics was also studied. According to the calculation of heat and mass balance, the cold gas efficiency was estimated to the maximum at $O_2$/coal ratio of around 0.73. But small size gasifier such as ours required higher value of $O_2$/coal ratio than that of the theoretical estimation. On the optimal $N_2$/coal ratio, we noticed that the coal feed rate was intimately related with the transporting gas pressure and the pipe diameter.

• Journal of Microbiology and Biotechnology
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• v.4 no.2
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• pp.95-101
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• 1994

The effects of glycine on cell growth and L-omithine production were investigated in shake-flask and jar fermentor cultures of a citrulline auxotrophic mutant, Brevibacterium ketoglutamicum BK 1046. In the shake-flask culture, the optimal concentration of glycine for L-ornithine production was found to be 20 g/l. In the jar fermentor culture with the glycine at an initial concentration of 20 g/l, L-ornithine production increased by 28%, compared to that of the culture with no glycine added. 37 g/l of L-ornithine was produced when additional feeding of glycine (5 g/l) was made. This was a significant improvement in L-ornithine production compared to that (ca. 24 g/l) of the corresponding batch culture conducted without glycine. According to the stoichiometric analysis with the batch fermentation results, the experimental and theoretical L-ornithine yields based on the glucose consumption were 0.24 and 0.59, respectively. This indicates that the performance of L-ornithine fermentation can further be improved by the supplementation of glycine and the development of a mutant strain possessing a higher growth yield.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.390-393
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• 2001

The optimal temperature, pH and aeration rate for spore production by Bacillus polyfermenticus SCD in 500 ml shake flask and 5-1 jar fermenter were found to be $32^{\circ}C$, 7.0 and 1.0 vvm. respectively. When batch culture processes was performed under optimized culture conditions. viable cells were $3.3{\times}10^{10}$ CFU/ml and spore cells were $3.3{\times}10^{10}$ CFU/ml. Fed-batch culture processes were also examined with regard to higer maximum viable cell and spore production. The highe viable cells and spores were obtained in 5-1 jar fermenter at 72 h cultivation time by strategy in an intermediate feeding mode with 60% glucose solution 150 ml and 5% soybean flour solution 150 ml fed to the fermenter twice, and the productivity of spore cells was significantly increased. Finally. volumetric productivity of spore cells on fed-batch culture indicated $9.9{\times}10^8$ CFU/ml/h, which was approximately 2 times higher than batch culture. Thus, fed-batch culture show a promise as an industrial production method.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1555-1566
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• 2018

Proportional capacitor-current-feedback active damping (AD) is a common damping method for the resonance of LCL-type grid-connected inverters. Proportional capacitor-current-feedback AD behaves as a virtual resistor in parallel with the capacitor. However, the existence of delay in the actual control system causes impedance in the virtual resistor. Impedance is manifested as negative resistance when the resonance frequency exceeds one-sixth of the sampling frequency ($f_s/6$). As a result, the damping effect disappears. To extend the system damping region, this study proposes a virtual resistor-inductor-capacitor (RLC) AD method. The method is implemented by feeding the filter capacitor current passing through a band-pass filter, which functions as a virtual RLC in parallel with the filter capacitor to achieve positive resistance in a wide resonance frequency range. A combination of Nyquist theory and system close-loop pole-zero diagrams is used for damping parameter design to obtain optimal damping parameters. An experiment is performed with a 10 kW grid-connected inverter. The effectiveness of the proposed AD method and the system's robustness against grid impedance variation are demonstrated.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.303-306
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• 2009

High temperature solid oxide fuel cells (SOFCs) offer a clean, pollution-free technology to electrochemically generate electricity at high efficiencies. Solid oxide fuel cells in several different designs have been investigated; these include planar and tubular geometries. The tubular type cell is widely researched due to it have advantages about thermal expansion and sealing issues. Unfortunately, lab scale tubular cell for testing has thermal expansion and sealing problems. The previous Jig for lab scale tubular cell testing has many sealing problems. When we feed fuel gas to jig inlet, ceramic glue sealant has amount of gas expansion pressure, because temperature of feeding gas changes ambient temperature to high temperature ($700{\sim}900^{\circ}C$). Furthermore, when we carry out long time test, something like degradation test, crack of ceramic glue sealant due to weakness of mechanical properties can make stop working the test. Additionally, we reduce setting process for assembling, because micanite is not required drying or debinding process.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.5
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• pp.95-106
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• 1992

Active control of acoustic noise is an application area of adaptive digital signal processing with increasingly interest along the last year. This work studies the implementation of the multichannel LMS filter and the application of this algorithm for the reduction of the noise inside a vechicle cabin using a number of 'secondary sources' drived by adaptive filtering of a reference noise source. Firstly, we propose the use of an adaptive method for the time-varient optimal convergence factor. Secondly, we propose the use of adaptive delayed inverse model to estimate the elastic-acoustic transfer function presented in vechicle cabin. The original, primary source is often periodic, with a known fundamental frequency. A suitably filtered reference signal can thus be used to drive the secondary sources. An algorithm is presented for adapting the coefficients of an FIR filter feeding such a secondary source in such a way as to minimize the output of a suitably placed microphone. In this algorithm, the coefficients of adaptive filter driving an array of secondary sources can be adapted to minimize the sum of the squares of the outputs of a number of error microphones. The multichannel LMS algorithm displays that such an algorithm is considered suitable to used for the global suppression of noise in vehicle cabin.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.562-566
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• 2014

Larvae of pandalid shrimp Pandalopsis japonica are benthic, and may prefer bottom to planktonic food items. Three diets, enriched Artemia meta-nauplii (AR), clam meat (CM), and crumbled shrimp (CD), were evaluated as food for early larvae in terms of biometric growth R:D ratios. Larvae fed AR and CM had significantly greater total length and dry weight than did larvae fed CD (P<0.05). Survival was significantly greater in larvae fed CM than in those fed AR and CD (P<0.05). R:D ratios were also significantly higher in larvae fed AR and CM than in those fed CD (P<0.05). Planktonic Artemia meta-nauplii containing high levels of fatty acids and amino acids were not suitable for either normal somatic growth or survival at early benthic larval stages. Furthermore, it is necessary to determine the optimal feeding duration to increase digestibility of AD. Thus, we propose that clam meat is the best diet for pandalid shrimp larvae.

• Journal of Industrial Technology
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• v.24 no.A
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• pp.17-22
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• 2004

In the study, we have developed a straightening system for 304 micro wires that are normally used in the medical and semi-conductor fields. To apply heat to the micro wires, we introduced the direct wire heating method which generates the thermal energy by the electrical resistance of the wire itself. To avoid the deterioration of the wire surface by the environment, such as the oxidation or the hydration, the $N_2$ gas was filled in the glass pipe in which the straightening process was being performed. A precision tension meter was also attached to control the tension of the wire during the heating and straightening process. In order to control the straightening process, several experimental investigations with varying the tension, the feeding velocity and the temperature (current) was carried out. As a result of experiments, we obtained the optimal processing conditions satisfying the straightness requirement of the micro wires.