• Aerospace Engineering and Technology
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• v.8 no.1
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• pp.197-206
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• 2009

To improve the aerodynamic efficiency of Smart Unmanned Aerial Vehicle (SUAV), vortex generators and flow fence are applied on the surface and the tip of wing. The initially applied vortex generator increased maximum lift coefficient and delayed the stall angle while it produced excessive increase in drag coefficient. It turns out reduction of the airplane's the lift/drag ratio. The new vortex generators with L-shape and two different height, 3mm and 5mm, were used to TR-S4 configuration to maintain the desired level of maximum lift coefficient and drag coefficient. Flow fence was also applied at the end of both wing tip to reduce the interaction between nacelle and wing when nacelle tilting angles are large enough and produce flow separation. To examine the effect of flow fence, flow visualization and force and moment measurements were done. The variation of the aerodynamic characteristics of SUAV after applying flow control devices are summarized.

• Korean journal of food and cookery science
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• v.6 no.2
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• pp.1-6
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• 1990

The purpose of this study was to investigate the effects of preheating and salt concentration on the fermentation rate and firmness of cucumber kimchi, and the relationship between firmness and the contents of pectin fractions, hemicellulose and cellulose during fermentation. For this purpose, pH, acidity, firmness and the contents of pectic fractions, hemicellulose and cellulose were studied. 1. The changes of pH and titratable acidity indicated that preheating and high salt concentration delayed the fermentation rate in cucumber kimchi. 2. After 9 days, preheated cucumber kimchi was firmer than nonpreheated cucumber kimchi. 3. During fermentation, the cucumber kimchi fermented at 5% NaCl was firmer than that femented at 2% NaCl. 4. After 9 days, preheated cucumber kimchi was higher in insoluble pectin (HCISP)content and lower in soluble pectin (HWSP & HXSP) content than nonpreheated cucumberkimchi and hese results in accord with those of firmness measurements. 5. During fermentation, the cucumber kimchi fermented at 5% NaCl was higher in insoluble pectin content and lower in soluble pectin content than nonpreheated cucumber kimchi, and these results were in accord with those of firmness measurement. 6. During fermentation, cellulose content decreased.

• Journal of the Korean Society of Food Science and Nutrition
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• v.19 no.4
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• pp.321-329
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• 1990

The present study was carried out to investigate the antioxidant effects of onion and ginger on the lipid peroxidation of mackerel during frozen storage. mackerels were reated with onion juice ginger juice tocopherol and BHA and stored at -18$^{\circ}C$ for 6 weeks. lipid peroxidation in samples was estimated by the periodical measurements of acid value iodine value peroxide value carbonyl value 2-thiobarbituric acid value and fatty acid composition. The treatments with ginger and onion were effective on the suppression of acid value and carbonyl value of makerel oil during 4 to 6 weeks of frozen storage. The iodine value was not affected by the treatments with various antioxidants, The production of peroxides was delayed by ginger or onion treatment, the TBA value of the sample muscles was not lowered by the treatments, The treatment with onion resulted in less changes in the contents of $\omega$-3 polyunsaturated fatty acids and in the P/S ration of fish oil than the control did. Results indicate that the applica-tion of ginger or onion juice on the surface of fishes may be useful to lower the degree of rancidity of fish during the froxaen storage.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.167.1-167
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• 2003

To maintain high quality and to extend the shelf life of intact and minimally processed apple cubes, the effect of heat shock on the texture and color of apple cubes (Fuji) was evaluated in this study. After peeled and cored, the apples were cut into cubes of 1.5 cm. The heat shock was immersion in heated water from 25$^{\circ}C$ to 95$^{\circ}C$ in 10$^{\circ}C$ increments for 2 min and cooling to storage temperature as soon as possible after heat treatment. The effect of heat treatment in terms of color and texture measurements with respect to time was investigated, respectively during 7 days storage at in LDPE film bags without sealing at 4$^{\circ}C$, and 95% relative humidity air. Results suggest that heat shock (55$^{\circ}C$, 2 min) may have effectively delayed browning, and there were significant changes in color of apple cube when the temperature of heat shock is above 75$^{\circ}C$. And hardness, stiffness and firmness, which were used to describe texture, behaved similarly in the textural qualities. It was shown that the texture of the apple cubes was decreased with temperature increase. The value of them were most decreased to 70% of the initial ones after treated with 85$^{\circ}C$ and 95$^{\circ}C$ on the lust day.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.2
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• pp.464-470
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• 1999

The purpose of this study was to investigate the effect of zinc intake on immune responses in high fat diet induced obese rats. The immune status was assessed by the measurements of immunoglobulins (IgG, A, and M) production by SRBC(sheep red blood cell) with mitogen in vivo. The delayed type hypersensitivity(DTH) response was also measured as an index of cell mediated immunity. The re sults are summarized as follows : 1) There were no significant differences in the feed intake, weight gain and feed efficiency ratio of obese rats by the different dietary zinc levels. 2) White blood cell (WBC) counts were significantly affected as the dietary zinc levels decreased. The capacity of Ig M production in obese rats was significantly higher in normal zinc group than that of low and high zinc group. Cell mediated immune response evaluated by means of DTH testing has also been found to be highly impaired by zinc deficiency and overload. From these observations, it was suggested that adequate levels of zinc may promote the immune function of obese individuals. The relationship and its functional role of the zinc in obesity remains to be further studied.

• Journal of Life Science
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• v.10 no.1
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• pp.52-60
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• 2000

Up to now, there have been done much efforts in regard to nitrate reductase activity (NRA) of dicotyledonous herbs and important crop monocotyledons, but few to wild plants having canopy structure such as Carex. The objective of the present study are to determine: a) the optimum in vivo NR assay conditions for leaf samples of Carex species, b) changes of NRA according to section within leaf and leaf ages, c) diurnal variations. Optimized assay media of each Carex species were determined. NRA of C. rostrata adapted to oligotrophic habitats is readily saturated at lower substrate concentration than those of C. distans and C. gracilis, adapted to meso- and eutrophic habitats, respectively. All Carex species investigated have higher NRA in leaves than in roots. NRA of all species showed maximal values at the middle section of each leaf and in the youngest fully expanded leaves. Compared to C. gracilis, NR in leaves of C. distans was adapted readily to the light period. On the whole, Carex showed rather delayed diurnal variation. Even if the in vivo nitrate reductase assay based on nitrite estimation does not give an accurate estimation of total nitrate reduced, it still serves as a useful tool to find out relative differences in varying environmental conditions. Additionally, in vivo RNA measurements are helpful to understand nitrate reduction and basic nitrogen metabolism of Carex species having different canopy structure.

• Journal of the korean society of oceanography
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• v.38 no.2
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• pp.80-86
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• 2003

The horizontal distributions of $^{224}Ra$ (half life=3.4 days) and $^{223}Ra$ (half life=11.3 days) were measured in surface seawaters of the Nakdong River estuary and the South Sea of Korea in April and October 2002. In order to determine these short-lived Ra isotopes, we used a delayed coincidence counter which is much more rapid and accurate than traditional methods. In an estuarine mixing zone (salinity, ~l6 ppt), the activities of $^{224}Ra\;and\;^{223}Ra$ were much greater than what would be expected from a mixture of freshwater and seawater in the Nakdong River estuary. This excess Ra may be a result of Ra desorption from fresh sediments originating from the river upstream. However, in the more open areas of the Nakdong River estuary (salinity>30 ppt) and the South Sea of Korea, $^{224}Ra\;and\;^{^{223}Ra$ activities decreased exponentially as a function of distance offshore. Using the decrease of $^{223}Ra$ with distance offshore in the South Sea of Korea, we estimated the apparent horizontal eddy diffusivities. The apparent eddy diffusion coefficients in South Sea of Korea are calculated to be approximately $3500-8000\;\textrm{m}^2/sec$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.2
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• pp.134-140
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• 2019

Oxide ($SnO_2$)/metal alloy (Cu(Ni))/oxide ($SnO_2$) multilayer films were fabricated using the magnetron sputtering technique. The oxide and metal alloy were $SnO_2$ and Ni-doped Cu, respectively. The structural, optical, and electrical properties of the multilayer films were investigated using X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectrophotometry, and 4-point probe measurements, respectively. The properties of the $SnO_2/Cu(Ni)/SnO_2$ multilayer films were dependent on the thickness and Ni doping of the mid-layer film. Since Ni atoms inhibit the diffusion and aggregation of Cu atoms, the grain growth of Cu is delayed upon Ni addition. For $250^{\circ}C$, the Haccke's figure of merit (FOM) of the $SnO_2$ (30 nm)/Cu(Ni) (8 nm)/$SnO_2$ (30 nm) multilayer film was evaluated to be $0.17{\times}10^{-3}{\Omega}^{-1}$.

• International Journal of High-Rise Buildings
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• v.11 no.4
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• pp.287-300
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• 2022

Unconventional structures are getting more popular in recent days. Large-span roofs are used for many structures, such as airports, stadiums, and conventional halls. Identifying the pressure distribution and wind load acting on those structures is essential. This paper offers a collaborative study of computational fluid dynamics (CFD) simulations and wind tunnel tests for assessing wind pressure distribution for a building with a combined slender curved roof. The hybrid turbulence model, Improved Delayed Detached Eddy Simulation (IDDES), simulates the open terrain turbulent flow field. The wind-induced local pressure coefficients on complex roof structures and the turbulent flow field around the structure were thus calculated based upon open terrain wind flow simulated with the FLUENT software. Local pressure measurements were investigated in a boundary layer wind tunnel simultaneous to the simulation to determine the pressure coefficient distributions. The results predicted by CFD were found to be consistent with the wind tunnel test results. The comparative study validated that the recommended IDDES model and the vortex method associated with CFD simulation are suitable tools for structural engineers to evaluate wind effects on long-span complex roofs and plan irregular buildings during the design stage.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.47.4-48
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• 2021

Gravitationally lensed Type Ia supernovae may be the next frontier in cosmic probes, able to deliver independent constraints on dark energy, spatial curvature, and the Hubble constant. Measurements of time delays between the multiple images become more incisive due to the standardized candle nature of the source, monitoring for months rather than years, and partial immunity to microlensing. While currently extremely rare, hundreds of such systems should be detected by upcoming time-domain surveys. Others will have the images spatially unresolved, with the observed lightcurve a superposition of time delayed image fluxes. We investigate whether unresolved images can be recognized as lensed sources given only lightcurve information and whether time delays can be extracted robustly. We develop a method that we show can identify these systems for the case of lensed Type Ia supernovae with two images and time delays exceeding ten days. When tested on such an ensemble the method achieves a false positive rate of ≲5%, and measures the time delays with the completeness of ≳93% and with a bias of ≲0.5% for time delay ≳10 days. Since the method does not assume a template of any particular type of SN, the method has the potential to work on other types of lensed SNe systems and possibly on other transients.