• Food Science and Preservation
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• v.6 no.4
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• pp.448-455
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• 1999

The starters, 0.3% of Leuconostoc mesenteroides, Lactobacillus brevis and Lactobacillus fermentum, were added in radish juice to process the radish juice by single and mixed cultures. The radish Juice was fermented for 7 days at 25$^{\circ}C$, 20 days at 15$^{\circ}C$, and 36 days at 5$^{\circ}C$. When fermented at 25$^{\circ}C$, the number of lactic acid bacteria in the juice made with mixed culture was higher than that of the single culture. But, juice fermented at low temperatures (15∼5$^{\circ}C$), the addition of starters was not effective, although there were some differences by inoculation strains. Although there was a little differences by inoculation strains, the content of nonvolatile organic acid and L-ascorbic acid were found more in the juice inoculated with lactic acid bacteria than the juice not inoculated. When the single and mixed cultures at the optimal maturity were tested, the significant difference was found at 5% level except the yeasty and moldy smell and the unripe taste. According to the preference test, the mixed-cultured radish juice incubated at 25$^{\circ}C$with Lactobacillus brevis and Leuconostoc mesenteroides were evaluated superior to commercial Dongchimi. As a result, taste and quality of radish juice was improved by addition of starters.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.3
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• pp.242-247
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• 1988

To elucidate the relationship of the quality of aromatic tobaccos to their chemical constituents, certain chemical components and leaf quality by price were compared among cured leaves produced under different soil moisture levels during growing season. As the soil moisture increased, plant height and the length and width of largest leaf increased. days to flower was shortened and total chlorophyll and carotenoid content of green leaf decreased. As the soil moisture increased, leaf quality was deteriorated. The content of nicotine, pet. ether ext. and total nitrogen increased with slight increment of nonvolatile organic acids and higher fatty acids, but ash content and pH of cured leaves decreased under high soil moisture content. Volatile organic acids such as 3-methyl pentanoic acid, the main compounds contributing to the aroma of oriental tobacco, and most volatile neutrals decreased conspicuously under high soil moisture. The content of pet. ether ext., volatile organic acids, volatile neutrals, ash and pH of cured leaves were found to be the appropriate factors for the quality evaluation of aromatic leaves grown under under different soil moisture.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.1
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• pp.88-92
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• 2023

The ferroelectricity in Hf_0.5Zr_0.5O₂ (HZO) thin films is one of the most interesting topics for next-generation nonvolatile memory applications. It is known that a crystallization process is required at a temperature of 400℃ or higher to form an orthorhombic phase that results in the ferroelectric properties of the HZO film. However, to realize the integration of ferroelectric HZO films in the back-end-of-line, it is necessary to reduce the annealing temperature below 400℃. This study aims to comprehensively analyze the ferroelectric properties according to the annealing temperature (350-500℃) and time (1-5 h) using a furnace as a crystallization method for HZO films. As a result, the ferroelectric behaviors of the HZO films were achieved at a temperature of 400℃ or higher regardless of the annealing time. At the annealing temperature of 350℃, the ferroelectric properties appeared only when the annealing time was sufficiently increased (4 h or more). Based on these results, it was experimentally confirmed that the optimization of the annealing temperature and time is very important for the ferroelectric phase crystallization of HZO films and the improvement of their ferroelectric properties.

• Analytical Science and Technology
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• v.19 no.4
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• pp.290-300
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• 2006

Disinfection by-products(DBPs), such as volatile trihalomethanes and the nonvolatile organochlorine acids, created by chlorination have been extensively studied. However MX which contributes 20-50% of the mutagenic activity in drinking water began to people's attention since 1990. Its chemical name is 3-chloro-4-dichloromethyl-5-hydroxy-2(5H)-furanone. According to WHO guidelines its concentration should be controlled, but its value has not been set up. Due to analytical difficulties in measuring this compound at such a low concentrations and lack of information on toxicity to human. Because concentration (ng/L) of MX in drinking water is low traditional testing methods are ineffective. Therefore this study compared LLE and SPE and have chosen SPE to improve preconcentration. MX has been identified in chlorinated drinking water samples in several countries but not in korea Therefore this study analyzed concentration of MX in different water sources and in spring water. This study examined the causes of changing MX content. Chlorine dosage, seasons, water temperature and distance from the source was all discoverd to be relavant. MX was analyzed in various treatment to find optimum disinfection methods. The outcome was that the concentration of MX was minimized when using biological activated carbon-O3 and granular activated carbon.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.702-707
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• 2012

During the last few decades, toxic chemicals used in various industries have caused global pollution and the side products such as carbon dioxide and methane gas have contributed to global warming. Thus, it is desirable to develop new alternative solvents. It is well known that ionic liquids display a variety of environmentally friendly physical properties: nonvolatile, nonflammable, wide electrochemical windows, high inherent conductivities, wide thermal operating ranges, chemically inert, and limited miscibilities with organic solvents. Because of these characteristics, ionic liquids are promising candidates as solvents for synthetic chemistries, catalysis, and gas separations. In this study, we synthesized morpholiunium salts as N-ethyl-N-methylmorpholine Bromide, N-butyl-N-methylmorpholine Bromide, N-octyl-N-methylmorpholine Bromide, N-ethyl-N-methylmorpholine Tetrafluoroborate, N-butyl-N-methylmorpholine Tetrafluoroborate, N-octyl-N-methylmorpholine Tetrafluoroborate, N-ethyl-N-methylmorpholine Hexafluorophosphate, N-butyl-N-methylmorpholine Hexafluorophosphate, and N-octyl-N-methylmorpholine Hexafluorophosphate. The melting points, decomposition temperatures and electrochemical stabilities of the salts were measured by DSC, TGA, and CV, respectively. The salts with halide anion showed high melting points ($150{\sim}200^{\circ}C$), low decomposition temperatures ($200{\sim}230^{\circ}C$), narrow electrochemical stabilities (3.4~3.6 V). The synthesized salts with inorganic anions, on the other hand, presented low melting point ($50{\sim}110^{\circ}C$), high decomposition temperatures ($250{\sim}380^{\circ}C$), wide electrochemical stabilities (6.1~6.3 V). We also found that the properties depend on the length of the carbon chain.

• Development and Reproduction
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• v.10 no.3
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• pp.159-168
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• 2006

Rodents and many other mammals have two chemosensory systems that mediate responses to pheromones, the main and accessory olfactory system, MOS and AOS, respectively. The chemosensory neurons associated with the MOS are located in the main olfactory epithelium, while those associated with the AOS are located in the vomeronasal organ(VNO). Pheromonal odorants access the lumen of the VNO via canals in the roof of the mouth, and are largely thought to be nonvolatile. The main pheromone receptor proteins consist of two superfamilies, V1Rs and V2Rs, that are structurally distinct and unrelated to the olfactory receptors expressed in the main olfactory epithelium. These two type of receptors are seven transmembrane domain G-protein coupled proteins(V1R with $G_{{\alpha}i2}$, V2R with $G_{0\;{\alpha}}$). V2Rs are co-expressed with nonclassical MHC Ib genes(M10 and other 8 M1 family proteins). Other important molecular component of VNO neuron is a TrpC2, a cation channel protein of transient receptor potential(TRP) family and thought to have a crucial role in signal transduction. There are four types of pheromones in mammalian chemical communication - primers, signalers, modulators and releasers. Responses to these chemosignals can vary substantially within and between individuals. This variability can stem from the modulating effects of steroid hormones and/or non-steroid factors such as neurotransmitters on olfactory processing. Such modulation frequently augments or facilitates the effects that prevailing social and environmental conditions have on the reproductive axis. The best example is the pregnancy block effect(Bruce effect), caused by testosterone-dependent major urinary proteins(MUPs) in male mouse urine. Intriguingly, mouse GnRH neurons receive pheromone signals from both odor and pheromone relays in the brain and may also receive common odor signals. Though it is quite controversial, recent studies reveal a complex interplay between reproduction and other functions in which GnRH neurons appear to integrate information from multiple sources and modulate a variety of brain functions.