• Journal of the Korean Ceramic Society
• /
• v.50 no.3
• /
• pp.231-237
• /
• 2013

Thermodynamic modeling of the $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ complex ferrite system has been adopted as a rational approach to establish routes to better synthesis conditions for pure phase $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ complex ferrite. Quantitative analysis of the different reaction equilibria involved in the precipitation of $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ from aqueous solutions has been used to determine the optimum synthesis conditions. The spinel ferrites, such as magnetite and substitutes for magnetite, with the general formula $MFe_2O_4$, where M= $Fe^{2+}$, $Co^{2+}$, and $Ni^{2+}$ are prepared by coprecipitation of $Fe^{3+}$ and $M^{2+}$ ions with a stoichiometry of $M^{2+}/Fe^{3+}$= 0.5. The average particle size of the as synthesized $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$, measured by transmission electron microscopy (TEM), is 14.2 nm, with a standard deviation of 3.5 nm the size when calculated using X-ray diffraction (XRD) is 16 nm. When $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ ferrite is annealed at elevated temperature, larger grains are formed by the necking and mass transport between the $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ ferrite nanoparticles. Thus, the grain sizes of the $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ gradually increase as heat treatment temperature increases. Based on the results of Thermogravimetric Analysis (TGA) and Differential Scanning Calorimeter (DSC) analysis, it is found that the hydroxyl groups on the surface of the as synthesized ferrite nanoparticles finally decompose to $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ crystal with heat treatment. The results of XRD and TEM confirmed the nanoscale dimensions and spinel structure of the samples.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.38 no.3
• /
• pp.283-289
• /
• 1993

Effect of sulfur dioxide gas on the growth and yield of soybean growing in the On-San Industrial Complex area was evaluated using the isoquant contour lines of the sulfur dioxide in air of the area. Average concentration of sulfur dioxide monitored in the Industrial Complex from July 17 to September 17 was 0.77mg / 100cm$^2$ PbO$_2$/day. Soil pH ranged from 4.2 to 6.5. Yield losses were estimated by 5～30% due to the effect of sulfur dioxide. Liming could relieve the yield reduction to some extent. The cumulative $SO_2$ concentration, as measured by PbO$_2$ method, for two months of active vegetative growth to early ripening stage has shown a good negative correlation with soybean yield. But, pod number and 100 grain weight did not show the correlation with the concentration of sulfur dioxide. These results suggest that sulfur dioxide affect chronically and cumulatively the growth of soybean plants.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.66 no.1
• /
• pp.29-36
• /
• 2021

Recently, phytochemicals in whole grains have received increasing attention because the increased consumption of whole grains and whole grain products has been associated with a reduced risk of chronic diseases. Among the phytochemicals in whole wheat, arabinoxylan influences various physiological activities and can aid the treatment of numerous health conditions, either directly or indirectly. In this study, 614 wheat germplasms, collected from the world, were cultivated in 2018 and harvested in 2019 in South Korea. The qualities of these whole grains, including seed protein content, were evaluated using the NIR spectrophotometric method, and arabinoxylan content was determined using enzymatic methods. The ash content was 0.36 to 2.80% and protein content was 7.66 to 20. The SDS-sedimentation for gluten complex ability ranged from 26.85 to 80.63 mL, and protein content showed a high correlation with SDS-sedimentation in the germplasms. Verify the result of the enzymatic method of arabinoxylan, the reliability of the experimental method was determined through repeatability, reproducibility, and recovery. The average value of the 614 resources was 51.64 mg/g of whole grain, and when classified according to the country of origin, the South Korean origin resources tended to have a higher content compared to the genetic resources of other countries. These results are expected to be used as basic data for setting standards for whole grain quality in wheat breeding systems.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.38 no.6
• /
• pp.513-523
• /
• 1993

Varietal difference in structural and physical characteristics of rice starch and interrelationships between these starch properties and the physicochemical components of rice grains were investigated for twenty four rice varieties, which were considerably different in amylose content, gelatinization temperature and gel consistency, to obtain the basic informations for diversifying the utility of rice grains and for developing various rice cultivars adaptable to rice food processing. Wave length of maximum absorbance for blue color reaction of starch-I$_2$ complex was 520nm for glutinous rice and 560～600nm for nonglutinous rice. The higher amylose rice showed the longer wave length but there was considerable difference of the wave length among rice materials with similar amylose content. Varietal difference in frequency distribution of debranched starch molecules by isoamylase hydrolysis was largest in amylose fraction, the longest fraction(Fr. I), and was next bigger in intermediate fraction(Int.Fr.) and the ratio between short and long glucose chain of amylopectin fraction(Fr. III /Fr. II). The Fr. III / Fr II ratio was higher in glutinous rice than in nonglutinous one but it was considerably different among nonglutinous rice varieties without any connection with amylose content. The lower alkali digestible rice showed the longer half-hydrolysis time in acid solution. Both soft and hard gel rice varieties in gel consistency test revealed significant varietal difference of 50% acid hydrolysis time. The harder rice in gel consistency exhibited the less frequency of short branch fraction of amylopectin (Fr. III) and the higher amylose content. Twenty four rice varieties were cleary classified by upper two principal components contracted from structural or physical traits of rice starch and some physicochemical properties of rice grain by principal component analysis. The 1st and 2nd principal components can be characterized to components related with amylose and amylopectin structure respectively.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.36 no.2
• /
• pp.69-79
• /
• 2008

Landscape indices are effective tools to explain the spatial structure and patterns of ecological landscape including area/density, shape, core area, isolation/proximity, contagion/interspersion, and connectivity. More than 100 indices have been developed and an increasing amount of research explains changes in urban spaces using the indices. However, landscape indices have a high level of sensitivity to the scale of analysis - grain size and extent. If the scale sensitivity of indices is not considered, the research may produce inaccurate results. This study examines the scale sensitivity of landscape indices to find relatively stable indices in the complex geographical features of Korea. The scale sensitivity was analyzed using 20 categories of grain size and 41 categories of extent change. Landsat TM and ETM+ images of five years - 1985, 1991, 1996, 2000 and 2003 - were used, and 54 class level indices mounted on the FRAGSTATS program were examined. The results are as follows: First, according to the analysis of the scale sensitivity, 19 out of 54 class level indices were found to be stable to scale change. Second, the scale sensitivity was closely related to the green area ratio, and the typical threshold of change was $40{\sim}50%$. Third, among the 16 indices which were frequently used in the research in Korea, only 6 indices were relatively stable to the scale change. These results can be an effective basis for the selection of indices in the landscape ecology research in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.4
• /
• pp.497-502
• /
• 2019

Metal oxide nanostructures are promising materials for advanced applications, such as high sensitive gas sensors, and high capacitance lithium-ion batteries. In this study, tin oxide (SnO) nanostructures were grown on a Si wafer substrate using a two-zone horizontal furnace system for a various substrate temperatures. The raw material of tin dioxide ($SnO_2$) powder was vaporized at $1070^{\circ}C$ in an alumina crucible. High purity Ar gas, as a carrier gas, was flown with a flow rate of 1000 standard cubic centimeters per minute. The SnO nanostructures were grown on a Si substrate at $350{\sim}450^{\circ}C$ under 545 Pa for 30 minutes. The surface morphology of the as-grown SnO nanostructures on Si substrate was characterized by field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). Raman spectroscopy was used to confirm the phase of the as-grown SnO nanostructures. As the results, the as-grown tin oxide nanostructures exhibited a pure tin monoxide phase. As the substrate temperature was increased from $350^{\circ}C$ to $424^{\circ}C$, the thickness and grain size of the SnO nanostructures were increased. The SnO nanostructures grown at $450^{\circ}C$ exhibited complex polycrystalline structures, whereas the SnO nanostructures grown at $350^{\circ}C$ to $424^{\circ}C$ exhibited simple grain structures parallel to the substrate.

• Korean Journal of Agricultural Science
• /
• v.3 no.1
• /
• pp.39-51
• /
• 1976

As an accempt to increase thc efficiency of land use and the food production to achieve the national goal in the food self-sufficiency, nine cropping systems on the upper-land were examined in pure-stand and in mixtures of soybean, corn, potato and radish. The important conclusions of this study were summarized as follows; 1. The flowering date of soybean was two or three days earlier in pure-stand than in the mixture with corn. The maturing date two days earlier in the pure-stand than in the mixture with corn. The flowering and maturing dates were not different among various cropping systems in corn. 2. The stem length of soybean was significantly different among various cropping systems. Soybean in pure-stand was shorter in stem length than with corn. 3. The number of pods per soybean plant did not give any significant differences among various cultivation methods. 4. The length of internode and the number of nodes per soybean plant in the mixture with corn were greater than in the pure-stand. In the number of branches per plant this was reversed. 5. The average stem dry weight of soybean per 10a was not significantly different among various cultivation methods. 6. The soybean yield per 10a in the pure-stand was obviously greater than the mixture and there were significant differences among cultivation method within the mixture with corn in soybean yield. 7. The 1,000-grain weight of soybean was significantly different and those in the pure-stand was heavier than those in the mixture with corn. 8. Grain weight per soybean plant and the stem diameter in the pure-stand were significantly lesser than those in the mixture with corn. 9. In the comparisons of corn in the pure-stand and in the mixture with soybean, plant height, number of ear per 10a, mean ear weight and remember of grain per plant, 100-grain weight, ear length, ear girth and number of ear pel plant were not significantly different among various cultivation methods except for the grain yield per 10a. 10. In the economic analysis, the mixture with soybean and corn gave the greatest gross income. The combination 7 was the best which was 47.6% increase income comparing with the soybean pure-stand. 11. As it can be assumed, soybean plant was influenced greatly than corn by various cropping system. It is necessary to study more complex cropping system finding and giving more desirable multiple cropping system for the farmer.

• Korean Journal of Food Science and Technology
• /
• v.24 no.1
• /
• pp.1-6
• /
• 1992

Changes in protein distributiun, eletrophoretic patterns and amino acid composition were investigated during germination of malting barley. Fractionation of the protein complex in ungerminated malting barley resulted in a higher hordein fraction but less glutelin fraction of the protein complex in ungerminated malting barley resulted in a higher hordein fraction but less glutelin fraction as compared to germinated malting barley. As germination proceeded, NPN, globulin and glutelin fractions continued to increase, accmpanied by decreases in albumin and hordein fractions. The electrophoretic pattern of malting barley proteins showed three bands (molecular weight range of $15,000{\sim}41,000$ daltons) in albumin fraction, five bands ($19,000{\sim}61,000$ daltons) in globulin fraction, five bands ($18,000{\sim}56,000$ daltons) in hordein fraction and tour bands ($20,000{\sim}47,000$ daltons) in glutelin fraction, exhibiting quantitative changes in each fraction during germination. Amino acid analysis showed that glutamic acid, histidine, aspartic acid, serine, glycine, valine, alanine and leucine were major amino acids of proteins in malting barley grains. Glutamic acid increased slightly, but other amino acids showed no definite trend as germination proceeded.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.12
• /
• pp.3011-3015
• /
• 2009

Structural and thermo-analytical studies were carried out to understand the phase formation kinetics of the single phase $Bi_5Ti_3FeO_{15}$ (BTFO) nanocrystals in $Bi_2O_3-Fe_2O_3-TiO_2$, during the polymerized complex (PC) synthesis method. The crystallization of Aurivillius phase $Bi_5Ti_3FeO_{15}$ layered perovskite was found to be initiated and achieved under the temperature conditions in the range of ${\sim}$800 to 1050$^{\circ}C$. The activation energy for grain growth of $Bi_5Ti_3FeO_{15}$ nanocrystals (NCs) was very low in case of NCs formed by PC (2.61 kJ/mol) than that formed by the solid state reaction (SSR) method (10.9 kJ/mol). The energy involved in the phase transformation of Aurivillius phase $Bi_5Ti_3FeO_{15}$ from $Bi_2O_3-Fe_2O_3-TiO_2$ system was ${\sim}$ 69.8 kJ/mol. The formation kinetics study of $Bi_5Ti_3FeO_{15}$ synthesized by SSR and PC methods would not only render a large impact in the nanocrystalline material development but also in achieving highly efficient visible photocatalysts.

• Journal of Biosystems Engineering
• /
• v.23 no.3
• /
• pp.229-244
• /
• 1998

This study was performed to determine proper fan and heater management schemes for natural air drying of rough rice in round steel bin with stirring device under Korean weather conditions. A computer simulation model was developed to predict moisture content changes, energy requirements, and drymatter losses during drying of rough rice by natural air. Drying test was conducted to validate the simulation model using round steel bin of holding capacity of 300ton at Rice Processing Complex in Jincheon. The bin was filled with rough rice every day and mixing by stirring device. Moisture contents, ambient air temperatures, relative humidities, static pressures in plenum chamber in the bin, airflow rates, and electrical and fuel energy were measured. Relative errors of moisture content changes predicted by the simulation model were below 5ft, and relative errors of final moisture content, final grain weight, required energy ranged from 0.9% to 6%. These not levels indicated that the simulation model can satisfactorily predict the performance factors of natural air drying system such as drying rates and energr consumptions comparing error level of 10% to 15% in other drying simulation models generally used in dryer desists. Twelve different fan and heater management schemes were evaluated using the computer simulation model based on three hourly weather data from Suweon for the period of 1952-1994. The best management schemes were selected comparing the drymatter losses, required drying times, required energy consumptions. Operating fan without heating only when ambient relative humidity was below 85% or 90% appeared to be the most effective method of In operation in favorable drying weather. Under adverse drying climates or to reduce required drying time, operating fan continuously, and heating air with $1.5^{\circ}C$ temperature rise only when ambient relative humidity was over 85% appeared to be the most suitable method.