• Applied Biological Chemistry
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• v.28 no.2
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• pp.51-55
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• 1985

Dried black soybeans were soaked in water at the temperature range of $4^{\circ}C{\sim}100^{\circ}C$ and in salt or sugar solution at $100^{\circ}C$ in order to investigate their effects on the cooking ratio and diffusion property of color pigments. As the temperature increased, the equilibrated absorbance at 490nm of soaking water after 120min was linearly increased. The activation energy for diffusion of color pigments were found to be 4.23 Kcal/mole at the range of $60^{\circ}C{\sim}100^{\circ}C$ and 8.31 kca1/mo1e at $4^{\circ}C{\sim}60^{\circ}C$. The cooking ratio, % cooked beans after heating, of black soybeans were more affected by the salt concentration that of sugar. Both concentrations reduced the cooking ratio as they increased. The sorption isotherm of Kongjaban showed a quite different curves between the storage at $4^{\circ}C$ and $25^{\circ}C$. The sorption and desorption rates during storage could be represented by the equation of $log({\frac{dw}{dt}}{\times}10^3))=alogt+logb$ with a very high correlation.

• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.225-236
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• 2013

Among several bacteria examined, an antibacterial-producing Lactobacillus strain with probiotic characteristics was selected and identified based on 16S rRNA gene sequencing. Subsequent purification and mode of action of the antibacterial compounds on target cells including E. coli were investigated. Maximum production of the antibacterial compound was recorded at 18 h incubation at $30^{\circ}C$. Interestingly, antibacterial activity remained unchanged after heating at $121^{\circ}C$ for 45 min, 24 h storage in temperature range of $70^{\circ}C$ to room temperature, and 15 min exposure to UV light, and it was stable in the pH of range 2-10. The active compounds were inactivated by proteolytic enzymes, indicating their proteinaceous nature, and, therefore, referred to as bacteriocin-like inhibitory substances. Isolation and partial purification of the effective agent was done by performing ammonium sulfate precipitation and gel filtration chromatography. The molecular mass of the GFC-purified active compound (~3 kDa) was determined by Tris-Tricine SDS-PAGE. To predict the mechanisms of action, transmission electron microscopy (TEM) analysis of ultrathin sections of E. coli before and after antibacterial treatment was carried out. TEM analysis of antibacterial compounds-treated E. coli demonstrated that the completely altered bacteria appear much darker compared with the less altered bacteria, suggesting a change in the cytoplasmic composition. There were also some membrane-bound convoluted structures visible within the completely altered bacteria, which could be attributed to the response of the E. coli to the treatment with the antibacterial compound. According to the in vivo experiments oral administration of L. plantarum HKN01 resulted in recovery of infected BALB/c mice with Salmonella enterica ser. Typhimurium.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.21 no.1
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• pp.31-46
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• 1993

A radiative transfer model with two-stream/delta-Eddington approximation has been developed to calculate the vertical distributions of atmospheric heating rates and radiative fluxes. The performance of the model has been evaluated by comparison with the results of ICRCCM (Intercomparison of radiative codes in climate models). It has been demonstrated that the presented model has a capability to calculate the solar radiation not only accurately but also economically. The characteristics of ultraviolet-B radiation (UV-B; 280-320nm) are examined by comparison of relation between the flux at the top of atmosphere and that at the surface. The relation of UV-B is quadratic due to the strong ozone absorption in this band. Also, the dependence of the UV-B radiation on the stratospheric ozone depletion and stratospheric aerosol haze due to volcanic eruption on the stratospheric ozone depletion and stratospheric aerosol haze due to volcanic eruption has been tested with various solar zenith angles. The surface UV-B increases as the solar zenith angle increases. The existence of stratospheric aerosols causes an increase in the planetary albedo due to the aerosols' backscattering. The planetary albedo with aerosol's effect has been increases as the solar zenith angle is not sensitive. It may be caused by the fact that the aerosols' scattering effect becomes saturated with the relatively long path length in a large solar zenith angle. Finally, the regional impact of stratospheric aerosols due to volcanic eruption on the intensity of UV-B radiation at the surface has been estimated. A direct effect is that the flux is diminished at the low latitudes, while it is enhanced in the high latitudes by the aerosols' photon trap or twilight effect. In the high latitudes, both aerosols' scattering and ozone absorption have strong and opposite impacts to the surface UV-B radiation is located at the mid-latitudes during spring season in both hemispheres.

• Food Science and Preservation
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• v.13 no.2
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• pp.223-227
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• 2006

Optimal heat treatment conditions for maintaining the immune-activity of immunized milk with Helicobacter pylori antigen were studied Total bacterial count of immunized milk with H. pylori antigen decreased according to the increasing heating temperature and time. The viable tell number of immunized milk was $10^3\;CFU/mL$ after heat treatment for 30 min at $60^{\circ}C$, and coliform bacteria did not appear in immunized milk after heat treatment Immune-activity measured in terms of IgG concentration was maintained up to 99.99% after heat treatment for 30min at $60^{\circ}C$, but decreased rapidly below 50% after heat treatment above $70^{\circ}C$. The quality characteristics of immunized milk were examined during storage at $2^{\circ}C,\;4^{\circ}C\;and\;10^{\circ}C$. The pH, titratable acidity and total bacterial count were not changed significantly during 21 day storage at $2^{\circ}C\;and\;4^{\circ}C$, but rapidly changed after 7 day storage at $10^{\circ}C$. The immune-activity was kept well for 14 day storage at $2^{\circ}C,\;4^{\circ}C\;and\;10^{\circ}C$ but decreased rapidly after 14 days at every temperatures tested.

• Journal of Environmental Science International
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• v.6 no.3
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• pp.267-276
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• 1997

It has been studded that combustion and the production of air pollution of anthracite - bituminous coal blend In a fluidized bed coal combustor, The objects of thIns study were to investigate mixing characteristics of the particles as well as the combustibility of the low grade domestic anthracite coal and Imported h19h calorific bltununous coal in the fluidized bed coal combustor. They were used as coal samples ; the domestic low grade anthracite coal with heating value of 2,010kca1/kg and the Imported high grade bituminous coal with beating value of 6,520kca1/kg. Also, the effects of air flow rate and anthracite fraction on the reaching time of steady state condition have been studied. The experimental results are presented as follows. The time of reaching to steady state was affected by the temperature variation. The steady state time was about 120 minute at 300sc1h which was the fastest. It has been found that $O^2$ and $CO^2$ concentration were reached steady state at about 100 minute. It has been found that $O^2$ concentration decreased and $CO^2$ concentration increased as the height of fluidlzed bed Increased. It was found that splash zone was mainly located from 25cm to 35cm above distributor. Also, as anthracite traction Increased, the mass of elutrlatlon particles Increased, and $CO^2$ concentration decreased. As gk flow rate Increased,$O^2$ concentration decreased and $CO^2$ concentration increased. Regardless of anthracite fraction and flow rate, the uncombustible weight percentage according to average diameter of elutriation particles were approldmately high In the case of One Particles. As anthracite traction and k now rate Increased, elutriation ratio Increased. As anthracite fraction was increased, exit combustible content over feeding combustible content was Increased. Regardless of anthracite fraction, size distribution of Ued material from discharge was almost constant. Over bed temperature 85$0^{\circ}C$ and excess air 20% , the difference of combution efficiencies were little. It is estimate that the combustion condition In anthracite-bituminous coal blend combustion is suitable at the velocity 0.3m/s, bed temperature 85$0^{\circ}C$, the excess air 20%.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.391-397
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• 2012

The depletion of conventional oil reserves and the increasing energy need in developing countries such as China and India result in exceeding oil demand over supply. As a solution of the problem, the efficient utilization of heavy oil has been receiving more and more interest. In order to utilize heavy oil, upgrading processes are required. Among the upgrading processes, thermal decomposition is thought to be relatively simple and economical. In this study, to understand basic characteristics of thermal decomposition of heavy oil, we conducted pyrolysis experiments of deasphalted oil (DAO) produced by a solvent deasphalting process. DAO is a mixture of many components and consists mainly of materials of carbon number 20~40. For the comparison with results of DAO pyrolysis, additional pyrolysis experiments with single materials of carbon number 30 ($C_{30}H_{62}$, $C_{30}H_{58}O_4S$, $C_{30}H_{63}O_3P$) were conducted. Pyrolysis experiments were carried out non-isothermally with variation of heating rate (10, 50, $100^{\circ}C$/min) in a thermogravimetric analyzer. Average pyrolysis activation energy determined by using Arrhenius method, Ingraham and Marrier method, and Coats and Redfern method was 72~99 kJ/mol. In the activation energy calculated by Ozawa-Flynn-Wall method, DAO had wider variation than other single materials.

• KIEE International Transaction on Systems and Control
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• v.2D no.2
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• pp.78-91
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• 2002

In the thermal power plant, there are six manipulated variables: main steam flow, feedwater flow, fuel flow, air flow, spray flow, and gas recirculation flow. There are five controlled variables: generator output, main steam pressure, main steam temperature, exhaust gas density, and reheater steam temperature. Therefore, the thermal power plant control system is a multinput and output system. In the control system, the main steam temperature is typically regulated by the fuel flow rate and the spray flow rate, and the reheater steam temperature is regulated by the gas recirculation flow rate. However, strict control of the steam temperature must be maintained to avoid thermal stress. Maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature versus changes in fuel flow rate, difficulty of control of the main steam temperature control and the reheater steam temperature control system owing to the dynamic response characteristics of changes in steam temperature and the reheater steam temperature, and the fluctuation of inner fluid water and steam flow rates during the load-following operation. Up to the present time, the Proportional-Integral-Derivative Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on the characteristic comparison of the PID controller and the modified 2-DOF PID Controller (Two-Degrees-Freedom Proportional-Integral-Derivative) on the DCS (Distributed Control System). The method is to design an optimal controller that can be operated on the thermal generating plant in Seoul, Korea. The modified 2-DOF PID controller is designed to enable parameters to fit into the thermal plant during disturbances. To attain an optimal control method, transfer function and operating data from start-up, running, and stop procedures of the thermal plant have been acquired. Through this research, the stable range of a 2-DOF parameter for only this system could be found for the start-up procedure and this parameter could be used for the tuning problem. Also, this paper addressed whether an intelligent tuning method based on immune network algorithms can be used effectively in tuning these controllers.

• Plant Journal
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• v.10 no.2
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• pp.38-47
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• 2014

Renewable Portfolio Standards was introduced into the system in Korea in 2012. Interest in the unutilized and renewable energy sources is increasing. and these being actively investigated. An organic rankine cycle has emerged as an alternative in order to take advantage of bio-gas engine heat of sewage treatment plants whose capacity is 1500 kW. The organic rankine cycle power system was simulated by a simulator which is a commercial program of power plant design and performance analysis. The biogas engine is operated by $460^{\circ}C$ and 2.7 kg/s flow rate in the sewage treatment plant. Working fluids(R-601a, R-123, R-245fa) are selected to use in ORC power system in this temperature range. It was the isopentane that is the best performance among three working fluids. It could be obtained net power of 163.1 kW and efficiency of 13.66% from isopentane in the simulation.

• Korean Journal of Agricultural Science
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• v.35 no.2
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• pp.183-191
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• 2008

In order to make a functional jam containing garlic, sugar, acid and pectin were mixed with garlic and concentrated by heating the mixture under atmosphere or vacuum conditions. And changes of some physico-chemical properties of the garlic jam(i.e., color, textural properties, vitamin C) were investigated during storage at $30^{\circ}C$. It was found that lightness(L) was higher in sample of vacuum concentration than that in atmosphere concentration and redness(a) and yellowness(b) were higher in sample of atmosphere concentration. During the storage lightness was found to decrease for all samples with more drastic decrease in sample of atmosphere concentration where browning was more severely observed after 8 weeks of storage. In terms of textural properties, hardness, chewiness and gumminess were higher in sample of atmosphere concentration than that in vacuum concentration. And springiness and cohesiveness were higher in sample of vacuum concentration. Although sensory score for garlic jam found to be lower than that for the existing strawberry jam, the present garlic jam might have high marketability if considering its physiological value.

• Journal of the Korean Chemical Society
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• v.30 no.4
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• pp.394-402
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• 1986

Detonation reaction in L.P.G./$O_2$ mixture gas has been investigated over the L.P.G. concentration range of 3∼45 volume%. The variation of detonation velocity with mixture ratio is very interesting as it shows and inflection point near at the stoichiometric ratio. This might be ascribed to the fact that the detonation reactions at fuel-rich condition and fuel-lean condition proceed via different mechanisms. The maximum detonation velocity of 2.65km/sec occurs not at stoichiometric ratio(${\phi}$=1) but at fuel-rich condition (${\phi}$=1.57). Assuming that a stable detonation wave must propagates with the constant velocity, The upper and lower limit of detonation were determined and found to be 40.0 and 3.40 L.P.G. volume% respectively. The shock-heating technique was also utilized for the measurement of self-ignition temperature onsetting a stable detonation wave at varous mixture ratios. The self-ignition temperature at stoichiometric ratio is $742{\pm}3{\circ}K$ and the self-ignition temperature increases as the mixture ratio deviates from the stoichiometric condition.