• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.401-408
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• 2014

In membrane bio-reactor (MBR), the aeration control is one of the important independent variables to decrease fouling and to save energy with shear stress change on the membrane surface. The paper was carried out for numerical simulation of 3-dimensional fluid flow phenomena of the cylindrical bioreactor with submerged flat membranes equipped in the center and supplied the air from the bottom by using the COMSOL program. The viscosity and temperature of solution were assumed to be constant, and the specific air demand based on permeate volume ($SAD_p$) defined as scouring air per permeate rates was used as a variable. The calculated CFD velocities were compared with those of the velocity meter measurement and video image analysis, respectively. The results were good agreement each other within 11% error. For fluid flow in the reactor the liquid velocity increased rapidly between the air diffuser and membrane module, but the velocity decreased during flowing of the membrane module. Also, the velocity increased as it was near from the reactor wall to the central axis. The calculated shear stress on the membrane surface showed the highest value at the center part of the module bottom side and increased as aeration rate increased. Especially, the wall shear stress increased dramatically as the aeration rate increased from 0.15 to 0.25 L/min.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.475-481
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• 1999

Yeast extracts were prepared using either autolysis or enzymatic digestion methods for industrial application of the Saccharomyces cerevisiae B24 strain developed previously to have high RNA content. Extraction ratio of yeast extract from yeast cell reached 65% when autolysis of yeast slurry having 10% solid content was induced at $50^{\circ}C$ and pH 5.0 by agitating with 100 rpm. However, neither 5'-IMP nor 5'-GMP was detected from the autolyzate. In another attempt to prepare a yeast extract S. cerevisiae B24 culture was treated at $90^{\circ}C$ and then treated by various enzymes including ${\beta}-1,3-glucanase$, phosphodiesterase (nuclease P1), adenylic deaminase, and a protease. The yeast extract prepared by the enzymatic digestion method contained 3.2g of 5'-IMP and 5'-GMP/100g dry yeast extract.

• Korean journal of applied entomology
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• v.38 no.2
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• pp.85-91
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• 1999

Torymus sinensis was found to be a solitary ectoparasitoid attacking the larvae ofDryocosmus kuriphilus. The sex ratio of Torymus sinensis was close to 1 : 1 in foreign chestnut varieties.Under constant temperatures of 15"C, 20$^{\circ}$C, and 25"C, the preoviposition period and longevity of theadult was longer at lower temperatures when fed on honey. Most of the Torymus sinensis female havemature eggs in their ovaries just after emergence. The number of mature eggs reached to average 22.5individuals per female in four days, which was the highest value, after the emergence and then decreasedgradually. Eggs were laid on the larvae of the host or attached on inner surface of the gall chamber. Theeggs were oval in shape, measuring 0.49 mm length and 0.13 mm width and the color of the justoviposited egg was milky white. The larvae appeared in one day after being deposited at 20$^{\circ}$C. Thepupae, 2.25 mm length for female and 1.89 mm length for male, was milky white in color just afterpupation but became black later. In Kangwon Province, development period of chestnut galls formated byDryocosmus kuriphilus were mid April to late May and its primary parasitoid, Torymus sinensis adult,emerged from withered previous year galls in early April to early May. This species has one generation ina year, and hibernated with the matured larvae. hibernated with the matured larvae.

• Solar Energy
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• v.12 no.3
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• pp.70-83
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• 1992

The interaction between the surface radiation and the mixed convection transport from an isolated thermal source, with a uniform surface heat flux input and located in a rectangular enclosure, is stuied numerically. The enclosure simulates a practical system such an air cooled electric device, where an air-stream flows through the openings on the two vertical walls. The heat source represents an electric component located in such an enclosure. The size of this cavity is $0.1[m]{\times}0.1[m]$. The inlet velocity is assumed as 0.07[m/s] and the inlet temperature is maintained as $27^{\circ}C$. The inflow is kept at a fixed position. Laminar, two dimensional flow is assumed, and the problem lies in the mixed convection regime, governed by buoyancy force and surface readiation. The significant variables include the location of the out-flow opening, of the heat source and the wall emissivity. The basic nature of the resulting interaction betwwn the externally induced air stream and the buoyancy-driven flow generated by the source is investigated. As a result, the best location of the heat source to make the active heat transfer is 0.075[m] from the left wall on the floor. The trends observed are also discussed in terms of heat removal from practical systems such as electric circuitry.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.2
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• pp.193-204
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• 1984

The enzymatic properties of the alkaline AL-protease, which had been prepared from the crude zymolyase of Arthrobzoter luteus, was investigated together with its active amino acid residue. Complete inactivaton of the proteolytic activity of AL-protease by either DFP or PMSF was simultaneously accompanied by the loss of its lytic effect on the lysis of yeast cell wall. In the reaction, AL-protease showed the pattern of inactivation to decrease very slowly, as compared to that of chymotrypsin, and that enzyme and DFP were found to react with a molar ratio of 1 : 1. The preparation of AL-protease exhibited no hydrolytic activity in any substrates of polysaccharases, playing a significant role in the lysis of yeast cell wall. The optimum pH and temperature of AL-protease was pH 10.5 and $65^{\circ}C$, respectively. It also showed stability in the pH range from 5 to 11 and at the temperature below $65^{\circ}C$. Through the identification of the amino acid residue in the active site of the $^{32}P$-diisopropylph-osphorylated(DIP) AL-protease modified specifically with $^{32}P$-labeled DFP, AL-protease was found to be a DFP-sensitive which has a mole of active serine residue involved in its proteolytic activity per mole of the enzyme.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.12
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• pp.1852-1857
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• 2014

The aim of this study was to compare the anti-inflammatory activities of Spirulina maxima treated with ultrasonication and water extraction process. S. maxima extracted via ultrasonication showed low cytotoxicity (16.90%) in a normal human cell line, CCD-986sk. Especially, S. maxima ultrasonication extract showed the highest DPPH radical scavenging activities (46.82%) compared to water extract (31.30%) at $100^{\circ}C$. In addition, ultrasonication extract showed a high amount of flavonoids (21.60 mg/g) and total phenols ($8.36{\mu}g/mL$). Nitric oxide production by 1.0 mg/mL of S. maxima ultrasonication extract strongly inhibited ($1.3770{\mu}M$), whereas water extract showed lower inhibition ($1.5784{\mu}M$). TNF-${\alpha}$ and IL-6 cytokines were effectively inhibited by 1.0 mg/mL of S. maxima ultrasonication extract, which shows strong antioxidant activities. Based on these results, it can be concluded that the ultrasonication process increase anti-inflammatory activity of S. maxima extract.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.229-239
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• 2018

The purpose of this study was to effectively produce the biosugar from cell wall of lipid extracted microalgae (LEA) by using microwave-assisted pretreatment without enzymatic hydrolysis process. Response surface methodology (RSM) was applied to optimization of microwave-assisted pretreatment conditions for the production of biosugar based on enzyme-free process from LEA. Microwave power (198~702 W), extraction time (39~241 sec), and sulfuric acid (0~1.0 mol) were used as independent variables for central composite design (CCD) in order to predict optimum pretreatment conditions. It was noted that the pretreatment variables that affect the production of glucose (C6) and xylose (C5) significantly have been identified as the microwave power and extraction time. Additionally, the increase in microwave power and time had led to an increase in biosugar production. The superimposed contour plot for maximizing dependent variables showed the maximum C6 (hexose) and C5 (pentose) yields of 92.7 and 74.5% were estimated by the predicted model under pretreatment condition of 700 w, 185.7 sec, and 0.48 mol, and the yields of C6 and C5 were confirmed as 94.2 and 71.8% by experimental validation, respectively. This study showed that microwave-assisted pretreatment under low temperature below $100^{\circ}C$ with short pretreatment time was verified to be an effective enzyme free pretreatment process for the production of biosugar from LEA compared to conventional pretreatment methods.

• Journal of the Korean Society of Safety
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• v.20 no.4 s.72
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• pp.171-179
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• 2005

It is essential to understand the role of wall lining materials when they are exposed to a fire from an ignition source. Full-scale test methods permit an assessment of the performance of a wall lining material. Fire growth models have been developed due to the costly expense associated with full-scale testing. The models require heat flux maps from the ignition burner flame as input data. Work to date was impeded by a lack of detailed spatial characterization of the heat flux maps due to the use of limited instrumentation. To increase the power of fire modeling, accurate and detailed heat flux maps from the ignition burner are essential. High level spatial resolution for surface temperature can be provided from an infrared camera. The objective of this study was to develop a heat flux mapping procedure for a room test burner flame to a wall configuration with surface temperature information taken from an infrared camera. A prototype experiment was performed using the ISO 9705 test burner to demonstrate the developed heat flux mapping procedure. The results of the experiment allow the heat flux and spatial resolutions of the method to be determined and compared to the methods currently available.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.631-636
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• 2002

Lethality of high intensity light pulse on the pre-determined microbial populations has been investigated. Prior to the treatment, Lactobacillus plantarum, Lactobacillus brevis, Leuconostoc mesenteroides and Pediococcus pentosaceus were cultivated separately onto the surface of Lactobacilli MRS agar. Pre-determined microbial populations were applied to the test media and these sample were exposed to high intense light source with an exposure time ranging from 1 to $2500\;{\mu}s$. Results showed that at least 200 light pulses of $1\;{\mu}s$ duration were required to reduce L. Plantarum cells by 90% at 25 kV, the greater the number of light pulses, the larger the reduction in viable cell numbers. Viable cells of L. plantarum and the others were reduced by more than 5 and 6 log cycles at the upper exposure level of $750\;{\mu}s$, respectively. These study shows that pulsed light emissions can significantly reduce populations of lactic acid bacteria on exposed surface with exposure times. Killing efficiency for L. plantarum significantly increased with decreasing the distance between the lamp and the surface of samples.

• Food Engineering Progress
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• v.15 no.4
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• pp.398-403
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• 2011

A dielectric barrier discharge plasma (DBDP) treatment system was fabricated and the optimum operating conditions for the plasma generation were determined in order to explore the potential of cold plasma as a non-thermal proessing technology. The microbial inactivation performance of the system was also evaluated against Staphyloocus aureus. The system consisted of power supply, transformer, electrode assembly and sample treatment plate. The input power was 220 V single phase AC and amplified to 10.0-50.0 kV on a transformer. A pulsed sine wave of frequency 10.0-50.0 kHz was introduced to the electrode embedded in ceramic as a dielectric barrier material in order to generate plasma at atmospheric pressure. Higher currents and consequently greater power were required for the plasma generation as the frequencies increased. A homogeneous and stable plasma was generated at currents of 1.0-2.0, and frequencies of 32.0-35.3 kHz. The optimum electrode-gaps for the plasma generation were 1.85 mm without loaded samples. More power was consumed as the electrode-gaps increased. The practically optimum electrode- gap was, however, 2.65 mm when samples were treated on slide-glasses for microbial inactivation. The maximum temperature increase after 10 min treatment was less than 20$^{\circ}C$, indicating no microbial inactivation effect by heat and thereby insuring a non-thermal method. The DBDP inactivation effect against Staphyloocus aureus increased linearly with treatment time up to 5 min, but plateaued afterward. More than 5 log reduction was achieved by 10 min treatment at 1.25 A.