• Korean Journal of Environmental Agriculture
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• v.36 no.3
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• pp.175-183
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• 2017

BACKGROUND:The Aromatic rice which is characterized by the flavor of Nurungji when cooked rice, and consumption is increasing recently. The purpose of this study was to investigate the physicochemical characteristics and aroma components of five aromatic rice cultivars according to transplanting time. METHODS AND RESULTS: Quantitative analysis of protein, fat, fatty acid and essential amino acid for five aroma rice cultivars(Hyangmibyeo 2 ho, Aromi, Mihyang, Aranghyangchal, Heughyang)and transplanting time was analyzed by crude protein analyzer, gas chromatography (GC), liquid chromatography (LC) and viscosity analysis was done by using rapid viscosity analyzer (RVA). The content of 2-acetyl-1-pyrroline (2AP) was determined by gas chromatography mass spectrometer. (GC-MS) As a result, the average protein and lipid contents were 6.5% and 2.4%, respectively. The content of essential amino acid showed the highest content at 104.4mg/g. There was no significant change in normal nutrients during the transplanting time. By RVA, cv.Hyangmibyeo 2 ho showed the highest peak and total setback viscosities and lowest breakdown viscosity in early transplantation. The content of 2AP in flavor varieties and transplanting time was quantitatively analyzed by GC-MS. Among the cultivars, Aromi showed the highest 2AP contents at $66.7{\mu}g/100gin$ normal transplanting time. CONCLUSION: cv.Aromi and Hyangmibyeo 2 ho were excellent physicochemical properties and 2AP components contents amongaromatic rice cultivars tested. Theiroptimaltime to transplant was at the beginning of June in the area of Miryang.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.6
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• pp.1060-1067
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• 2001

Effect of various thickening agents on kakdugi fermentation was investigated by measuring physicochemical and sensory properties during fermentation at 2$0^{\circ}C$. Paste of seven kinds of thickening agents (wheat flour (WF), waxy rice flour (WR), corn starch (CS), acid modified starch (AM), aretylated distarch adipate (AA), hydroxypropyl distarch phosphate (PP) and xanthan gum (XG) ) at 0.25% concentration was added to kakdugi. Total acidity during fermentation was not different among thickening agents, but slightly lower in XG than control at the 7th day of fermentation. At 0 day of fermentation, free sugar amount were higher in thickening agent addition groups than control, but rapidly decreased to below control at the 7th day of fermentation, except XG. Glucose and fructose which were the major free sugars, decreased rapidly during fermentation, whereas mannitol increased in all samples. Viscosity of kakdugi liquid was much higher in thickening agent addition groups than control at 0 day of fermentation, but rapidly decreased from 1 day of fermentation. However, initial viscosity was maintained only in XG. Hardness at the 7th day of fermentation was higher in WR, PP, XG than control. The result of sensory evaluation shows that there were no significant difference in sour odor, sour taste and savory taste among samples. Moldy odor was higher in WR, WF and AM, but was not significantly different in XG, PP, AA compared to control. Viscosity of XG and PP, and starchy taste of XG were higher than those of control. Overall preference of XG, AM, PP were not significantly different from that of control. Xanthan gum was considered to be a good thickening agent for kakdugi but it is necessary to find a minimum concentration for kakdugi since starch taste of xanthan gum.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.494-500
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• 2003

The effects of $Al_2$O$_3$ addition upon the sintering range of clay-EAF dust (the specified wastes produced from steel making process) system body which would be used as a constructing bricks were investigated. The slope of apparent density to sintering temperature decreased for Clay-dust body containing 5~15 wt% A1203 sintered at 1200-125$0^{\circ}C$, and the absorption(%) of specimen sintered above 125$0^{\circ}C$ decreased due to the formation of open pores produced by pore bloating. For the specimen without any $Al_2$O$_3$ addition sintered at 1275$^{\circ}C$, the major phase was cristobalite, the small amount of mullite (3Al$_2$O$_3$ 2SiO$_2$) formed and the hematite (Fe$_2$O$_3$) remained. In the Clay-dust system body containing $Al_2$O$_3$ 15 wt%, however, the cristobalite disappeared and the major phase was mullite. Also the part of $Al_2$O$_3$ reacted with hematite to form hercynite (FeAl$_2$O$_4$). From the these results, addition of $Al_2$O$_3$ to Clay-dust system body enlarges a sintering range; decreasing an apparent density and absorption slop to sintering temperature owing to consumption of liquid phase SiO$_2$ at higher temperature and gas-forming component Fe$_2$O$_3$ at reduced atmosphere which would decrease an amount of liquid formed and increase the viscosity of the liquid produced during the sintering process.

• Korean journal of food and cookery science
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• v.19 no.6
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• pp.783-793
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• 2003

The effects of various kinds of starch (mungbean, potato, corn and a blend of potato and com starch) on the quality characteristics of muhwakwa-pyun were studied according to the storage duration. The sweetness, pH and total acidity of muhwakwa extract were analyzed, as were the Visco/Amylograph viscosity profile and DSC thermodynamic characteristics of starches. For quality characteristics, color difference, instrumental texture characteristics and sensory characteristics were compared. The sweetness of muhwakwa extract was satisfactory but the total acidity was low for Kwa-pyun manufacture. Therefore, its pH was adjusted to 3.4 by adding 10％ citric acid with an amount of 1％ of total liquid. From the Visco/Amylograph viscosity profile and DSC thermodynamic characteristics of starches, a blend of potato and com starch was found to be easy to cook and form a gel but a little more resistant than the other starches in terms of retrogradatin. Lightness (L) and yellowness (b) of Kwa-pyun increased while its redness (a) decreased by the storage. The color became whiter and the clarity decrease regardless of the kinds of starch, which became obvious after 3 days of storage. The hardness, springiness, adhesiveness and cohesiveness tended to decrease with storage, which was weak in a blend starch. The overall acceptability of Kwa-pyun made with a blend of potato and com starch was evaluated as being the best among the samples tested. Therefore, for traditional kwa-pyun manufacture manufacture mungbean starch might be replaced with a blend of potato and corn starch which is less expensive and easily available in the market nowadays.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.367-375
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• 2010

Understanding the interactions between earth materials and fluids is essential for studying the diverse geological processes in the Earth's surface and interior. In order to better understand the interactions between earth materials and fluids, we explore the effect of specific surface area and porosity on structural parameters of pore structures. We obtained 3D pore structures, using random packing simulations of porous media composed of single sized spheres with varying the particle size and porosity, and then we analyzed configurational entropy for 2D cross sections of porous media and cube counting fractal dimension for 3D porous networks. The results of the configurational entropy analysis show that the entropy length decreases from 0.8 to 0.2 with increasing specific surface area from 2.4 to $8.3mm^2/mm^3$, and the maximum configurational entropy increases from 0.94 to 0.99 with increasing porosity from 0.33 to 0.46. On the basis of the strong correlation between the liquid volume fraction (i.e., porosity) and configurational entropy, we suggest that elastic properties and viscosity of mantle melts can be expressed using configurational entropy. The results of the cube counting fractal dimension analysis show that cube counting fractal dimension increases with increasing porosity at constant specific surface area, and increases from 2.65 to 2.98 with increasing specific surface area from 2.4 to $8.3mm^2/mm^3$. On the basis of the strong correlation among cube counting fractal dimension, specific surface area, and porosity, we suggest that seismic wave attenuation and structural disorder in fluid-rock-melt composites can be described using cube counting fractal dimension.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.1-2
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• 2011

Hybrid rockets have lately attracted attention as a strong candidate of small, low cost, safe and reliable launch vehicles. A significant topic is that the first commercially sponsored space ship, SpaceShipOne vehicle chose a hybrid rocket. The main factors for the choice were safety of operation, system cost, quick turnaround, and thrust termination. In Japan, five universities including Hokkaido University and three private companies organized "Hybrid Rocket Research Group" from 1998 to 2002. Their main purpose was to downsize the cost and scale of rocket experiments. In 2002, UNISEC (University Space Engineering Consortium) and HASTIC (Hokkaido Aerospace Science and Technology Incubation Center) took over the educational and R&D rocket activities respectively and the research group dissolved. In 2008, JAXA/ISAS and eleven universities formed "Hybrid Rocket Research Working Group" as a subcommittee of the Steering Committee for Space Engineering in ISAS. Their goal is to demonstrate technical feasibility of lowcost and high frequency launches of nano/micro satellites into sun-synchronous orbits. Hybrid rockets use a combination of solid and liquid propellants. Usually the fuel is in a solid phase. A serious problem of hybrid rockets is the low regression rate of the solid fuel. In single port hybrids the low regression rate below 1 mm/s causes large L/D exceeding a hundred and small fuel loading ratio falling below 0.3. Multi-port hybrids are a typical solution to solve this problem. However, this solution is not the mainstream in Japan. Another approach is to use high regression rate fuels. For example, a fuel regression rate of 4 mm/s decreases L/D to around 10 and increases the loading ratio to around 0.75. Liquefying fuels such as paraffins are strong candidates for high regression fuels and subject of active research in Japan too. Nakagawa et al. in Tokai University employed EVA (Ethylene Vinyl Acetate) to modify viscosity of paraffin based fuels and investigated the effect of viscosity on regression rates. Wada et al. in Akita University employed LTP (Low melting ThermoPlastic) as another candidate of liquefying fuels and demonstrated high regression rates comparable to paraffin fuels. Hori et al. in JAXA/ISAS employed glycidylazide-poly(ethylene glycol) (GAP-PEG) copolymers as high regression rate fuels and modified the combustion characteristics by changing the PEG mixing ratio. Regression rate improvement by changing internal ballistics is another stream of research. The author proposed a new fuel configuration named "CAMUI" in 1998. CAMUI comes from an abbreviation of "cascaded multistage impinging-jet" meaning the distinctive flow field. A CAMUI type fuel grain consists of several cylindrical fuel blocks with two ports in axial direction. The port alignment shifts 90 degrees with each other to make jets out of ports impinge on the upstream end face of the downstream fuel block, resulting in intense heat transfer to the fuel. Yuasa et al. in Tokyo Metropolitan University employed swirling injection method and improved regression rates more than three times higher. However, regression rate distribution along the axis is not uniform due to the decay of the swirl strength. Aso et al. in Kyushu University employed multi-swirl injection to solve this problem. Combinations of swirling injection and paraffin based fuel have been tried and some results show very high regression rates exceeding ten times of conventional one. High fuel regression rates by new fuel, new internal ballistics, or combination of them require faster fuel-oxidizer mixing to maintain combustion efficiency. Nakagawa et al. succeeded to improve combustion efficiency of a paraffin-based fuel from 77% to 96% by a baffle plate. Another effective approach some researchers are trying is to use an aft-chamber to increase residence time. Better understanding of the new flow fields is necessary to reveal basic mechanisms of regression enhancement. Yuasa et al. visualized the combustion field in a swirling injection type motor. Nakagawa et al. observed boundary layer combustion of wax-based fuels. To understand detailed flow structures in swirling flow type hybrids, Sawada et al. (Tohoku Univ.), Teramoto et al. (Univ. of Tokyo), Shimada et al. (ISAS), and Tsuboi et al. (Kyushu Inst. Tech.) are trying to simulate the flow field numerically. Main challenges are turbulent reaction, stiffness due to low Mach number flow, fuel regression model, and other non-steady phenomena. Oshima et al. in Hokkaido University simulated CAMUI type flow fields and discussed correspondence relation between regression distribution of a burning surface and the vortex structure over the surface.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.3
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• pp.156-161
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• 2011

Objectives: Tetrahydrofuran (THF) is a colorless, water-miscible organic liquid with low viscosity at standard temperature and pressure. THF has been used as a solvent and a precursor for various syntheses of polymers. However, THF is known to irritate to the eyes, skin and mucus membranes. Overexposure by inhalation, ingestion or skin contact may produce nausea, dizziness, headaches, respiratory irritation and possible skin burns. The purpose of this study is to evaluate of the worker exposure and characteristics of workers in the workplaces that use or manufacture THF. Methods: Sixteen factories in Korea, which manufacture or use THF, were selected for this study and a total of 130 air samples including 104 time-weighted average (TWA) samples and 26 short-term exposure limit (STEL) samples, were collected. Air samples were collected with charcoal tube (100mg/50mg) and analyzed by gas chromatograph/flame ionization detector(GC/FID). Results: The TWA concentration of THF was 16.05ppm (GM) at PS script printing, 2.32ppm (GM) at PVC stabilizer, 1.03ppm (GM) at Lithium triethylborohydride, 0.63ppm (GM) at Polytetramethylene ether glycol(PTMEG), 0.42ppm (GM) at Manufacturing THF, 0.13ppm (GM) at Glue and 0.12ppm (GM) at synthetic rubber/resins. Two out of sampes for PS script printing exceeded 50ppm as 8-hour exposure limit of MOEL. The short term exposure to THF was 54.77ppm (GM) at PS script printing, 17.10ppm (GM) at PTMEG, 13.76ppm (GM) at Manufacturing THF, 2.86ppm (GM) at Lithium triethylborohydride, 0.87ppm (GM) at synthetic rubber/resins and 0.13ppm (GM) Glue. We found that the highest exposure process for both the TWA and STEL samples was PS script process. Two samples exceeded 100ppm as short term exposure limit of Ministry of Employment and Labor(MOEL). Conclusions: Characteristic of STEL concentration for THF is considerably different from TWA concentration in workplaces because workers could exposure high concentration of THF in a moment when they work irregularly schedule. So exposure controls for momentary works have to be prepared, and considered the skin absorption and inhale of THF.

• Korean Journal of Poultry Science
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• v.33 no.3
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• pp.239-248
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• 2006

Improvements in understanding the effects of dietary fermentable carbohydrates and their interaction with supplemental feed enzymes and the feed manufacturing process may lead to reductions in volatile organic compound (VOC) emissions from poultry manure. Starch digestibility has been improved by replacing ground wheat or barley with whole wheat or barley, but there was no consistent effect of cereal species or feed form on the pH value of the gizzard contents. Pelleting results in improvements in feed conversion from 0 to 12%. Starch digestibility has been reported to account for up to 35 % of the improvement in available metabolic energy as a result of xylase supplementation. Factors which affect starch utilization and non-starch polysaccharide (NSP) absorption include the presence of anti-nutrient facto. (ANF) in grains, the nature of grain starch, NSP and the digestive capacity of animals. Improvements in feed production technology have been made in enzyme stabilization, allowing some dry enzyme products to be pelleted after conditioning at up to $87.69^{\circ}C$ and liquid enzymes to be stored in the feed mill for up to low months prior to use. The soluble NSP, arabinokylans and beta-glucans are partially degraded into smaller fragments by enzymes. With fragmentation, the water holding capacity is decreased, which leads to a reduction in digesta moisture, wet feces, and dirty eggs from hens fed diets containing viscosity-inducing ingredients.

• Journal of Conservation Science
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• v.35 no.5
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• pp.480-493
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• 2019

In this study, the method for processing glue and glue-alum sizing from the dancheong ground treatment was evaluated with respect to weather resistance, and its effect on the conservation of dancheong was analyzed. Viscosity and pH of the glue and glue-alum specimen were measured and classified into three categories(none layer, glue layer, and glue-alum layer), which were further classified according to low concentration(four times for 2%) and high concentration(once for 10%). The base layer formation was subsequently classified into three categories based on pigment adoption, namely, Noerok(celadonite), Seokganju(terra rossa), and Jangdan(red lead). The completed specimen was subjected to a changing-environment experiment for evaluating weather resistance and observing the surface. Color variations were analyzed before and after the experiment. The results indicate that glue-alum sizing comprising 5% alum or 7% alum has strong acidity that can affect the life of dancheong, and the high level of 7% alum makes it difficult to create a solid coating layer. After ultraviolet irradiation, the specimen with 7% alum changes its color to yellow. Furthermore, after moisture absorption and drying, cracks can be observed on the entire specimen surface that corroborate the physical change. Additionally, gas-based corrosion causes marginal surface changes. Hence, the formation of a stable coating layer can be achieved by incorporating a low concentration glue solution that is almost neutral, and the application of glue-alum sizing having 2% concentration can aid in the conservation of dancheong.

• Journal of Applied Biological Chemistry
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• v.54 no.1
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• pp.1-6
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• 2011

${\gamma}$-PGA(poly-${\gamma}$-glutamic acid) is an unusual anionic polypeptide that is made of D- and L-glutamic acid units connected by amide linkages between ${\alpha}$-amino and ${\gamma}$-carboxylic acid groups. ${\gamma}$-PGA has been isolated from many kinds of organisms. Many Bacillus strains produce ${\gamma}$-PGA as a capsular material of an extracellular viscous material. It is safe for eating as a viscosity element of fermented soybean products such as Chungkookjang and Natto. It is biodegradable, edible and nontoxic toward humans and the environment and its molecular weight varies from ten thousand to several hundred thousand depending on the kinds of strains used. Therefore, potential applications of ${\gamma}$-PGA and its derivatives have been of interest in the past few years in a broad range of industrial fields such as food, cosmetics, medicine, water-treatment, etc. In this study, a bacterium, Bacillus subtilis GS-2 isolated from the Korean traditional seasoning food, Chungkookjang could produce a large amount of ${\gamma}$-PGA with high productivity and had a simple nutrient requirement. Based on carbon utilization pattern and partial 16S rRNA sequence analysis, the GS-2 strain was identified as B. subtilis. The determination of purified ${\gamma}$-PGA was confirmed with thin layer chromatography (TLC), high performance liquid chromatography (HPLC), fourier transform infrared (FT-IR) spectra, and $^1H$-nuclear magnetic resonance ($^1H$-NMR) spectroscopy.