• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1604-1612
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• 1999

The study was carried out to investigate the quality of the wet noodle added with the powders of nopal and nopalitos from Opuntia ficus-indica. The wet noodles were prepared to the ratio of 3, 6 and 9% (w/w) of the nopal and the nopalitos based on a flour weight. The initial pasting temperature and final viscosity in an amylograph decreased as the increase of the nopal and the nopalitos powders. A cooked weight and volume decreased with the increase of the nopal and the nopalitos powders, while a cooking loss increased. From the sensory evaluation, the wet noodles included 3% nopalitos and 6% nopal powders were similarly evaluated as the noodle used whole wheat flour. Bacterial counts of wet noodle with the nopal and the nopalitos powders were always lower than those of the control. Bacterial counts of wet noodle slowly increased as the increase of the amount of nopal and the nopalitos powders during storage at $4^{\circ}C\;and\;20^{\circ}C$. The methanol extracts from the nopal showed antimicrobial activities against Escherichia coli, Escherichia coli O157 : H7, Salmonella typhimurium, and Bacillus subtilis, while the extracts from the nopalitos showed antimicrobial activity only against Escherichia coli.

• Korean Journal of Microbiology
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• v.25 no.3
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• pp.221-228
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• 1987

The extracellular adenine deaminase from Nocardioides sp. J-275L was purified by the following techniques: ammonium sulfate fractionation, DEAE-Cellulose, DEAE-Sephadex A-50 column chromatography, and Sephacryl S-200 superfine gel filtration. The enzyme was partially purified about 3889.5-fold with about 5.2% yield by these procedures. The molecular weight of the enzyme was 39,000 by a calibrated Sephacryl S-200 superfine column chromatography. The enzyme was stable at pH 7.5 and up to $40^{\circ}C$. Glycerol was effective on the stabilization of the enzyme during storage. The optimum pH and temperature of the enzyme were around pH 7.5 and $40^{\circ}C$, respectively. The apparent Michaelis constant Km of the enzyme for adenine was $7.4\times 10^{-5}$M. The purine analogues, 6-chloropurine, 2,6-diaminopurine, 6-bromopurine, 4-aminopyrazolo [3.4-d]pyrimidine, and 8-azaadenine were substrates for the enzyme. 6-Dimethylaminopurine was a competitive inhibitor of the enzyme. The enzyme was inhibited by 1mM of $Cu^{2+}, Fe^{3+}, Pb^{2+}, Hg^{2+}$, and $Ag^{+}$, and 1mM of $\alpha$,$\alpha$'-dipyridyl, pentachlorophenol, and pCMB.

• Korean Journal of Construction Engineering and Management
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• v.15 no.3
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• pp.47-57
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• 2014

LNG plant projects tend to be implemented in overseas owing to its characteristics, so their project management scheme is somewhat different from those of general projects. Value chain in a LNG plant project includes exploration/production of gases, physical liquefaction/chemical conversion processes, transportation and storage. Key factors in the chain include liquefaction process (including ultra-low temperature liquefaction) to convert natural gas into liquid materials or fuel, and Front End Engineering Design (FEED) package, as well as Engineering, Procurement and Construction (EPC) technology comprising control, operation and construction. Success of a complex LNG plant project implemented in overseas depends on decision-making process in project management. Accordingly, to develop a decision-making model in of plant construction, the study extracted none factors in project management by EPC stage and assessed importance of each factor. The result showed that items in both project management and project risk management are important. Especially, the study developed a decision-making model in the construction stage of a LNG plant project based on the project management factors and importance assessment. The developed decision-making model would lay groundwork in building a decision-making system in construction stage of project management.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.49-55
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• 2018

Under the era of energy crisis, hydrogen energy is considered as one of the most potential alternative energies. Liquid hydrogen has much higher energy density per unit volume than gas hydrogen and is counted as the excellent energy storage method. In this study, Navier-Stokes equations based on 2-phase model were solved by using a computational fluid dynamics program and the liquefaction process of gaseous hydrogen passing through a cryogenic cooling tube was analyzed. The copper with high thermal conductivity was assumed as the material for cryogenic cooling tube. For different inlet velocities of 5 m/s, 10 m/s and 20 m/s for hydrogen gas, the distributions of fluid temperature, axial and radial velocities, and volume fractions of gas and liquid hydrogens were compared. These research results are expected to be used as basic data for the future design and fabrication of cryogenic cooling tube to transform the hydrogen gas into liquid hydrogen.

• Korean Journal of Food Science and Technology
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• v.46 no.4
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• pp.438-445
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• 2014

We examined biogenic amine (BA) production as well as the diversity of bacterial flora in 11 types of commercial makgeolli stored at 4 and $20^{\circ}C$. Moreover, we studied the BA-producing activity of three L. plantarum strains isolated from makgeolli. At $20^{\circ}C$, the BA content was highly increased and the denatured DNA bands were more variable in non-sterilized makgeolli compared to sterilized makgeolli. The major BAs produced in commercial makgeolli were histamine and putrescine. Histamine, tyramine, putrescine, and cadaverine were produced in excess by inoculation of the three L. plantarum isolates to makgeolli stored at $20^{\circ}C$ for 21 days. These results suggest that some L. plantarum strains in makgeolli can produce different types of BAs, depending on the extent of degradation of makgeolli.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.3
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• pp.433-437
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• 2002

Human milk is normally contaminated with various microorganisms, which seem to produce no ill effects. A contamination of hand-expressed and pump-expressed human milk is a major concern in the collection of storage milk. In this study we compared milks collected by two methods, hand expression and suction breast pump, to quantify differences in the degree of bacterial contamination. Thirty-one samples had been manually expressed. The mean of total bacterial counts was 10,600 CFU/mL (range: 360 ∼59,200 CFU/mL) and coliform counts was 43 CFU/mL (range: 20 ∼ 1,060 CFU/mL) in these samples. Whereas in the 118 breast pump-expressed samples, the mean of total bacterial counts was 20,200 CFU/mL (range: 240 ∼ 492,000 CFU/mL) and coliform counts was 158 CFU/mL (range: 4∼10,600 CFU/mL). There was no bacterial growth when the samples were incubated for 10 days at 4$\^{C}$. We also compared total bacterial growth in colostrum and in matured human milk for 24 hr at 20$\^{C}$ and 30$\^{C}$. Although bacterial growth had not shown for 24 hr at 20$\^{C}$, but shown slight growth in colostrum and rapidly increase in matured human milk for 24 hr at 30$\^{C}$. The coliform bacteria in all samples, particulary in formula milk, had grown at 20$\^{C}$ and 30$\^{C}$.

• Applied Microscopy
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• v.29 no.2
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• pp.241-253
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• 1999

Fertilization pattern of north temperate bats is known to be unique for their sperm storage in the female reproductive tract during hibernation (e.g. Korean greater horseshoe bats). They copulate in fall but their ejaculated spermatozoa survive until the next spring. In another words they can persist to survive during long hibernation under the cold condition $(8\sim13^{\circ}C)$ and are to be fertilized with the ovum ovulated in the next spring, so called delayed fertilization. The present study was designed to observe morphological and functional changes of spermatozoa plasma membrane of the bats, hamsters which are hibernators, and mice which are non-hibernators in the room and the cold (bat-hibernation) temperatures and to confirm influence of the temperature on spermatozoa; survival rate, acrosome reaction rate, protein distribution, $Na^+-K^+-ATPase$ activities and scanning electron microscopic histochemistry. Based on the experimental results obtained in the present study, there were no significant morphological and functional differences in the spermatozoa plasma membrane in both the room and cold (bat-hibernation) temperatures and such an absence of difference suggests that the spermatozoa plasma membrane might play a pertinent role as a protector for consistent fertilization during and after hibernation.

• Journal of Biosystems Engineering
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• v.27 no.1
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• pp.59-66
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• 2002

The objectives of the study were to analyze the acoustic characteristics related to the internal quality factors of watermelon(Citrulus Vulgaris Schrad). Among the various internal quality factors, only four factors such as ripeness, inside cavity, yellow belt and blood flesh were considered in this study. Relationships between the internal quality factors, the day after fruit set and the day after harvest were also investigated. Test apparatus was the same as the apparatus described in the previous study(Choi et at., 2000). The selected sample was divided into four groups; 69 samples used for ripeness tests 56 samples for ripeness test along the day after fruit set and for yellow belt detection, 60 samples for ripeness along the day after harvest 44 samples fur blood flesh detection. It was shown that the first peak frequencies shifted to the lower range and the energy ratios of the bandwidths between 0∼550 Hz to the bandwidths between 850∼2500 Hz increased as the day after fruit set elapsed. Since the acoustic responses of the watermelon such as frequency and magnitude began to change from 10 days after harvest, the storage period of watermelon in a normal temperature condition seemed to be approximately 10 days after harvest. The ratios of the first peak amplitude to the maximum peak amplitude fur the sound watermelon showed the higher value than that fur watermelon with cavity inside, and the separation between the sound and cavity inside could be accomplished by the ratio value of 0.25. The energy ratios (0∼550 Hz/850∼2,500 Hz) for the watermelon with cavity inside showed the higher value than 2.3. The frequency characteristics of the yellow belt watermelon appeared mostly in the range of 600∼900 Hz frequencies. The yellow belt watermelon showing the energy spectral density function at this frequency range to be over 70 seemed to be not a marketable commodity, The energy ratios(0∼550 Hz/850∼2,500 Hz) for the blood flesh watermelon showed the higher value than 3.5.

• Journal of Animal Science and Technology
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• v.60 no.11
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• pp.27.1-27.8
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• 2018

Background: Enteric methane ($CH_4$) accounts for about 70% of total $CH_4$ emissions from the ruminant animals. Researchers are exploring ways to mitigate enteric $CH_4$ emissions from ruminants. Recently, nano zinc oxide (nZnO) has shown potential in reducing $CH_4$ and hydrogen sulfide ($H_2S$) production from the liquid manure under anaerobic storage conditions. Four different levels of nZnO and two types of feed were mixed with rumen fluid to investigate the efficacy of nZnO in mitigating gaseous production. Methods: All experiments with four replicates were conducted in batches in 250 mL glass bottles paired with the ANKOM$^{RF}$ wireless gas production monitoring system. Gas production was monitored continuously for 72 h at a constant temperature of $39{\pm}1^{\circ}C$ in a water bath. Headspace gas samples were collected using gas-tight syringes from the Tedlar bags connected to the glass bottles and analyzed for greenhouse gases ($CH_4$ and carbon dioxide-$CO_2$) and $H_2S$ concentrations. $CH_4$ and $CO_2$ gas concentrations were analyzed using an SRI-8610 Gas Chromatograph and $H_2S$ concentrations were measured using a Jerome 631X meter. At the same time, substrate (i.e. mixed rumen fluid+ NP treatment+ feed composite) samples were collected from the glass bottles at the beginning and at the end of an experiment for bacterial counts, and volatile fatty acids (VFAs) analysis. Results: Compared to the control treatment the $H_2S$ and GHGs concentration reduction after 72 h of the tested nZnO levels varied between 4.89 to 53.65%. Additionally, 0.47 to 22.21% microbial population reduction was observed from the applied nZnO treatments. Application of nZnO at a rate of $1000{\mu}g\;g^{-1}$ have exhibited the highest amount of concentration reductions for all three gases and microbial population. Conclusion: Results suggest that both 500 and $1000{\mu}g\;g^{-1}$ nZnO application levels have the potential to reduce GHG and $H_2S$ concentrations.

• Journal of Navigation and Port Research
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• v.42 no.1
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• pp.9-16
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• 2018

The development of limited petroleum resources for use with mankind inevitably explores and seeks to develop oil fields in the deep sea area, under the rise of the oil prices market situation. The use of Oceanic Thermal Energy Conversion (OTEC) technology, which operates the power generation facility using the temperature differences between the deep water and the surface water, is progressing actively as a trend to follow. In this study, the application of the Discharged Thermal Energy Conversion (DTEC) was designed and analyzed under the condition that the supply condition of seawater used in the FPSO installed in the deep sea area is changed up to 400m depth. In this case, it was confirmed that the design of the system that can generate more electric power according to the depth of water is confirmed, by thus applying the DTEC system by taking the cooling water at a deeper water depth than the existing design water depth. The FPSO considers the similarity of the OTEC power generation facilities, and will apply the DTEC system to FPSO in the deep sea area to accumulate technology and the conversion to further utilize the OTEC power generation facilities after the end of life cycle of oil production, which could be a solution to two important issues, namely, resource development and sustainable development.