• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.5
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• pp.323-334
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• 2020

Since boundary layer transition has a significant impact on the aero-thermodynamic performance of hypersonic flight vehicles, capability of accurate prediction of transition location is essential for design and performance analysis. In this study, γ-Re_θt model is improved to predict transition of hypersonic boundary layers and validated. A coefficient in the production term of the intermittency transport equation that affects the transition onset location is constructed and applied as a function of Mach number, wall temperature, and freestream stagnation temperature based on the similarity numerical solution of compressible boundary layer. To take into account a Mach number dependency of transition onset momentum thickness Reynolds number and transition length, additional correlation equations are determined as function of Mach number and applied to Re_θc and F_length correlations of the baseline model. The suggested model is implemented to a commercial CFD code in consideration of practical use. Analysis of hypersonic flat plate and circular cone boundary layers is carried out by using the model for validation purpose. An improvement of prediction capability with respect to variation of Mach number and unit Reynolds number is identified from the comparison with experimental data.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.3 s.345
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• pp.39-48
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• 2006

In this paper, we analyze the spectral efficiency of multicarrier-code division multiple access (MC-CDMA) scheme. First, we derive a generalized formula for the spectral efficiency according to the number of subcarriers involved in, code division multiplexing and the number of codes used (i.e., loading factor), under a given set of channel coefficients. Also, we derive a generalized formula for spectral efficiency of various reduced-complexity systems that divide the full sets of subcarriers into several groups of subcarriers for code division multiplexing. Then, through these derivations, we establish an inter-relationship between the frequency selectivity and diversity order according to the number of multipaths. From the results, we choose the smallest code length while maximizing the diversity effect, provide an optimum subcarrier allocation strategy, and finally suggest a system structure for capacity-maximizing under the smallest code length. Through numerical analyses under simulated environments, we analyze the properties of spectral efficiency of various systems with reduced complexity and choose a major contributing factors to system design and a better system design methodology. Finally, we compare the spectral efficiency of the MC-CDMA scheme and orthogonal frequency division multiplexing (OFDM) scheme to make a relationship between both schemes.

• Food Science and Preservation
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• v.13 no.2
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• pp.154-160
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• 2006

Shelf-life of functional beverage for the purpose of body fat reduction during storage was estimated at different temperatures. To estimate quality change of functional beverage, vacuum gauge, sugar concentration pit acidify, Hunter's color value, browning color intensity, total cell count and sensory evaluation were measured periodically. Vacuum gauge, sugar concentration pH and acidity were little changed and total cell count was not detected. By using the correlation coefficient between sensory evaluation and physicochemical properties, b-value was chosen for quality index of functional beverage. $Q_{10}-values$ for shelf-life were in the range of $2.13{\sim}2.59$. When sensory evaluation was 2.5 at $50^{\circ}C$, storage period was 6.83 weeks. And shelf-life calculated by $Q_{10}-values$ were 73.89, 34.21 and 13.21 weeks in $20^{\circ}C,\;30^{\circ}C\;and\;40^{\circ}C$, respectively.

• Journal of Gifted/Talented Education
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• v.15 no.1
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• pp.67-84
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• 2005

In this study we investigated the adequacy of tools for distinction gifted students through the comparison these mutual relation on the basis of data, like paper test, the depths interview score, and the rest data((TTCT: Torrance Tests of Creative Thinking, IQ test, FASP: Find A Shape Puzzle, V.T: Visualization Tests and Exp: experimental ability test), and analysis data of EEG test for examining the adequacy of tools for identification gifted students. So, we developed Brain Wave gifted Index(G-Index) for finding another distinction ability as using brain waves data. The standard of index development use gifted brain characteristic in closed-eyes rest state which is judged like that characteristic of distinction between gifted and normal students is the most clear and consistence. That is, the degree of unified pattern between each object and gifted PCA pattern was defined by Pearson method which added spatial mutual index to weight concept. This refer to mean number of spatial PCA pattern. Searching for the possibility of distinction gifted gave distinction effect in 76%. The result of regression analysis on the basis of mutual relation between the rest data is . The probability formula for distinct gifted group is as follow. $$P=\frac 1{1+e^{-[-0.018(TTCT)+0.057(IQ)+1.916(FASP)+0.682(V.T)+0.088(Exp.)+0.034(G-Index)-57.510]}}$$ The result of this calculation showed that probability for distinct in gifted group was very good(95.0%). On the basis of upper result, tools for identification gifted students should be estimated as using many-sided estimation data whatever possible. And following study about development, and operation of tools for distinction suitable to gifted student in science should be progressed.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.8
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• pp.1182-1187
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• 2005

This study was designed to investigate the supplementary effects of Lentinus edodes which were harvested at different time period and part on acetylcholine content and its related enzyme activities in the brain of diabetic mouse model (KK mouse). We fed mice with standard diet (Control diet; CON) or 4 different kinds of experimental diets (DGC: on time harvested, cap of Dong Go; DGS: on time harvested, stipe of Dong Go; HSC: late harvested, cap of Hyang Sin: HSS: late harvested, stipe of Hyang Sin) to KK mouse for 8 weeks. Neurotransmitter such as acetylcholine contents, acetylcholinesterase activities, monoamine oxidase-B ac-tivities and lipid peroxide contents in the brain were measured. The results showed that acetylcholine content was significantly higher in DGC and HSC groups than CON group. The activities of acetylcholinesterase and monoamine oxidase-B enzyme were significantly inhibited in the brain of DGC and HSC groups compared with CON group. Lipid peroxide content was lower in DGC group than CON group. These results suggested that the cap of Lentinus edodes which were harvested on time and late time contain increased acetylcholine content and decreased acetylcholinesterase activities, monoamine oxidase-B activities and lipid peroxide contents. Thus the cap of Lentinus edodes which were harvested at different time periods may play an effective role in enhancing cognitive function.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.2
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• pp.217-223
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• 2008

Amylose and protein contents are important traits determining the edible quality of rice, especially in East Asian countries. Near-Infrared Reflectance Spectroscopy (NIRS) has become a powerful tool for rapid and nondestructive quantification of natural compounds in agricultural products. To test the practically of using NIRS for estimation of brown rice amylose and protein contents, the spectral reflectances ($400{\sim}2500\;nm$) of total 9,483 accessions of rice germplasm in Rural development Administration (RDA) Genebank ere obtained and compared to chemically determined amylose and protein content. The protein content of tested 119 accessions ranged from 6.5 to 8.0% and 25 accessions exhibited protein contents between 8.5 to 9.5%. In case of amylose content, all tested accessions ranged from 18.1 to 21.7% and the grade from 18.1 to 19.9% includes most number of accessions as 152 and 4 accessions exhibited amylose content between 20.5 to 21.7%. The optimal performance calibration model could be obtained from original spectra of brown rice using MPLS (Modified Partial Least Squares) with the correlation coefficients ($r_2$) for amylose and protein content were 0.865 and 0.786, respectively. The standard errors of calibration (SEC) exhibited good statistic values: 2.078 and 0.442 for amylose and protein contents, respectively. All these results suggest that NIR spectroscopy may serve as reputable and rapid method for quantification of brown rice protein and amylose contents in large numbers of rice germplasm.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.2
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• pp.273-278
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• 2017

This study was conducted to investigate the quality characteristics and antioxidant properties of cookies supplemented with 2~8% (w/w) Taraxacum coreanum powder (TCP). The pH and moisture content of cookie dough decreased significantly (P<0.05) while density was not influenced significantly by increasing levels of TCP. The spread ratio and loss rate of cookies increased significantly with increasing levels of TCP (P<0.05). Lightness, redness, and yellowness decreased significantly with higher amount of TCP (P<0.05). The use of TCP significantly increased hardness of cookies while 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activities were significantly elevated (P<0.05). The consumer acceptance test indicated that addition of 2% TCP had a favorable effect on consumer preferences in all attributes. Based on overall observations, cookies with 2% TCP can take advantage of the functional properties of TCP without sacrificing consumer acceptability.

• Journal of Animal Environmental Science
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• v.13 no.1
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• pp.21-28
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• 2007

This experiment was conducted to determine the effect of feed intake and water consumption on milk yield and manure production in milking cows. The average feed intake(dry matter) of milking cows were 19.5kg/hd/d. Spring(23.9kg) and fall(22.1kg) feed intake rates when higher than in the summer(17.0kg) and winter(15.3kg/hd/d). The average water consumption of milking cows were $77.2\ell/hd/d$. Summer showed the highest value$(85.5\ell/hd/d)$ and winter showed the lowest value$(62.2\ell/hd/d)$. The average milk yield during spring, summer, fall, and winter was 30.8, 24.0, 25.4, and 23.7kg/hd/d, respectively. Milk yield during spring was found to be statiscally greater than for the other seasons. Manure production of milking cows during spring, summer, fall, and winter was 64.4, 63.5, 60.4, and 51.0kg/hd/d, respectively. Consequently, a relatively high correlation between milk yield and water consumption$(R^2=0.7742)$, milk yield and feed intake$(R^2=0.7459)$, water, consumption and urine production$(R^2=0.7422)$, feed intake and feces production$(R^2=0.6044)$, and milk yield and feces production$(R^2=0.6920)$ were observed in milking cows. The other hand, correlation between water consumption and feces production$(R^2=0.2950)$, feed intake and urine production $(R^2=0.1985)$, and milk yield and urine production$(R^2=0.2335)$ were found to be relatively low. Therefore, correlation equation between milk yield and feed intake, milk yield and water consumption can be estimated from : $Y=0.1919X_1+11.181(R^2=0.7742),\;Y=0.8568X_2+9.3067(R^2=0.7459)$(Y=milk yield $X_1=water$ consumption, $X_2=feed$ intake).

• Journal of Radiation Protection and Research
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• v.24 no.2
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• pp.101-108
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• 1999

The influence of the relative humidity, the temperature and the velocity of supply air on evaporation rate has been studied with non-boiling forced evaporation system in order to treat very low level radioactive liquid wastes produced from the decontamination and decommissioning activities. Experimental data on the evaporation rate have been obtained with the divers variables and experimental equation of air velocity was also obtained by the correlation of those data. The decontamination factor of this system was also obtained by the experimental data from a simulated liquid waste containing Cs-137 radio isotope ; $DF=10^4$. Since the commercial system will be operated for the treatment of the very low level radioactive liquid waste produced from decontamination & decommissioning of TRIGA Mark-II&III research reactor, the environmental assessment has been conducted to improve the operational safety. Exposure dose rate for an individual member of general public was assessed, and it showed that it was very lower than individual dose limits. The release of radioactivity of radioisotope material (Cs-137) to the environment was assessed, and result showed that it was $4.637{\times}10^{-14}\;{\mu}Ci/cc$.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.587-590
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• 2013

Solid-liquid equilibria for mixtures composed of n-vinyl-2-pyrrolidone (NVP) and 2-pyrrolidone were measured as a basic study for the melt crystallization process to remove 2-pyrrolidone as impurity included in NVP. A differential scanning calorimeter (DSC) and a crystallizer were used and the experimental results obtained from two methods were similar. The mixture showed a eutectic system which has a single composition at the minimum melting temperature. Calculation results from simple thermodynamic equations were found in general agreements with present data. To determine the growth rate of NVP crystal which is important for the design of crystallization process, thicknesses of the crystal were measured with the time using a layer melt crystallizer. The growth rates increased as cooling temperatures decreased. Heat transfer coefficient correlated from present data was found to successfully describe the crystal growth behavior.