• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.189-189
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• 2008

Due to the environmental issue vast research is going on to replace the widely used lead contented piezoelectric materials. Bismuth sodium titanate (abbreviated as BNT) based bismuth sodium titanate-barium titanate (abbreviated as BNBT) ceramic was prepared by using modified method rather than conventional mixed oxide method. This modification was made to improve the properties of BNT based ceramic. In this procedure $BaTiO_3$ (abbreviated as BT) was prepared using conventional mixed oxide method. Analytical grade raw materials of $BaCO_3$ and $TiO_2$ were weighted and ball milled using ethanol medium. The mixed slurry was dried and sieved under 80 mesh. Then the powder was calcined at $1100^{\circ}C$ for 2 hours. This calcined BT powder was used in the preparation of BNBT. Stoichiometric amount of $Bi_2O_3$, $Na_2CO_3$, $TiO_2$ and BT were weighted and mixed by using ball mill. The used calcination temperature was $850^{\circ}C$ for 2 hours. Calcined powder was taken for another milling step. BNBT disks were pressed to 15 mm of diameter and then cold isostatical press (CIP) was used. Pressed samples were sintered at $1150^{\circ}C$ for 2 hours. The SEM microstructure analysis revealed that the grain shape of the sintered ceramic was polyhedral and grain boundary was well matched where as the sample prepared by conventional method showed irregular arrangement and grain boundary not well matched. And sintered density was better (5.78 g/cc) for the modified method. It was strongly observed that the properties of BNBT ceramic near MPB composition was found to be improved by the modified method compare to the conventional mixed oxide method. The piezoelectric constant dB of 177.33 pC/N, electromechanical coupling factor $k_p$ of 33.4%, dielectric constant $K_{33}^T$ of 688.237 and mechanical quality factor $Q_m$ of 109.37 was found.

• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.2
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• pp.65-68
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• 2008

Crop production in a country is very crucial not only in a country's crop self-sufficiency, but also in carbon recycle. Crop can capture and store the emitted $CO_2$ by cereal food consumption. However, imported cereal food is not concerned in carbon recycle and this hinders the accurate estimation of carbon recycle. Korea imports major grain products including wheat, corn, soybean, and rice and about 90% of the grain composition consists of carbohydrate, protein and lipid. Carbon portions in carbohydrate, protein and lipid are 45, 53, and 77%, respectively. When the carbon portions are digested and converted into $CO_2$ completely, one ton of rice, wheat, corn, and soybean can release 1.51, 1.63, 1.56, and 1.56 tons of $CO_2$ to the atmopshere, respectively. Based on this premise, the evolved $CO_2$ calculated from imported grains for the last 4 years in Korea was over 21 MT of $CO_2$. This amount is equivalent to 4.8 billion US dollars in the conception of carbon tax. These results suggest that a decrease in a cereal import(i.e, an increase in a country's crop self-sufficiency) can lower $CO_2$ release to the atmosphere.

• Journal of Animal Science and Technology
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• v.48 no.2
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• pp.227-236
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• 2006

Twenty four Hanwoo steers(average body weight=550.4±42.8kg) were used in the experiment to determine the effects of supplementing coated vitamin C+E with cottonseed on meat quality, meat color and carcass grade in Hanwoo steers fed brewers grain and cracked corn-based fermented feedstuff. Steers were randomly assigned to feeding groups of fermented feedstuff without any supplements(T1) and fermented feedstuff supplemented with coated vitamin C+E and cottonseed(T2). Ether extract content of longissimus dorsi was higher in T2 than in T1(p<0.05). Yellowness and hue-angle among surface colors of longissimus dorsi was lower(p<0.05) in T2 than in T1 but lightness was higher(p<0.05) in T2 than in T1. Ratio of yield grade ‘A’ was higher from T2 group than from T1 group. Marbling score was higher in T2 than in T1(p<0.05). Present results indicate that supplementation of coated vitamin C+E and cottonseed to brewers grain and cracked corn-based fermented feedstuff has positive effects on ether extract content, color, marbling score of longissimus dorsi in Hanwoo steers.

• Journal of Sensor Science and Technology
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• v.5 no.3
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• pp.93-100
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• 1996

Polycrystalline $Sr_{2}(Ta_{1-x}Nbx)_{2}O_{7}$ and $La_{2}Ti_{2}O_{7}$ ceramics having very high Curie temperatures were synthesized by the conventional oxide mixing method (CON) and the molten salt synthesis method (MSS). Physical characteristics and phase relationship of calcined powders, as well as the sintering behavior, the grain-orientation and dielectric properties of sintered ceramics were investigated as a function of composition and firing temperature. The single $A_{2}B_{2}O_{7}$ phase was synthesized by using the MSS method at 100 - $150^{\circ}C$ lower temperature compared to the CON method. As Nb content increased in $Sr_{2}(Ta_{1-x}Nbx)_{2}O_{7}$ ceramics, the Curie temperature and the dielectric constant at Curie temperature were raised, and the sintering behavior and the degree of grain-orientation were also improved at the same time. The use of MSS-derived powders made it possible to lower the sintering temperature and to improve the dielectric properties of the sintering samples. However, the piezoelectric properties as well as the grain-orientation were not improved any further by the MSS route.

• Applied Biological Chemistry
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• v.28 no.3
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• pp.182-186
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• 1985

In order to determine the optimum sowing date of peanut in the middle part of Korea, peanut's 100-grain-weight and physico-chemical compositions for peanut cultivars such as runner (Yeoju landrace), semi-spanish (Suweon No. 15) and spanish types (Wasedairu) to different seeding date which planted at interval of ten days from May 5 to July 4, in 1981, was carried out. The 100-grain-weight and crude fat of peanut were increased from May 5 to May 25, but after that decreased. And the 100-grain-weight of peanut was great in order of Wasedairu, Suweon No. 15 and Yeoju landrace. The highest amount of crude fat was seen in peanuts which was sown at May 25 and May 15. Unsaturated fatty acids are composed of $80{\sim}85%$ of oleic and linoleic acid, but saturated fatty acids are constituted of $10{\sim}15%$ of palmitic acid and $1{\sim}5%$ of stearic and arachidic acid. Composition ratio of fatty acid in peanut was changed greatly according to sowing date. According to the late sowing date linoleic and palmitic acid were increased but oleic acid was decreased, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.3
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• pp.205-210
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• 1986

A soil micromorphological study of clayey terrace soils in Yeongnam area was carried out to investigate the soil genetic features and to distinguish the soil parent materials. Dominant plasmic fabrics in the terrace soils were vosepic, mosepic, insepic, and masepic of sepic fabrics but the Geugrag and Upyeong in Yeongil sequence have an asepic fabrics. Embedded grain cutans in the terrace soils were characterized by having porphyroskelic related distribution. Among pedological features of the B horizons of the terrace soils, the argillic cutans of ferriargillans and glaebules of manganiferrous concretions were the dominant in mineralogical composition, and the papules are abundant in the most terrace soils indicating that the soils are generally old. The substrata of the Bancheon in Yeongcheon and Upyeong in Yeongil area were so different from the terrace deposits in plasmic fabrics that these soils were believed to be composed of bisequum profiles. Because of having the free grain cutans, it was considered that the substrata of Bancheon in Yeongcheon and Upyeong in Yeongil area might have a period of soil formation before deposition of the terrace materials.

• Korean Journal of Materials Research
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• v.29 no.4
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• pp.205-210
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• 2019

$Pb(Zr,Ti)O_3$ (PZT) is used for the various piezoelectric devices owing to its high piezoelectric properties. However, lead (Pb), which is contained in PZT, causes various environment contaminations. $(K,Na)NbO_3$ (NKN) is the most well-known candidate for a lead-free composition to replace PZT. A single crystal has excellent piezoelectric-properties and its properties can be changed by changing the orientation direction. It is hard to fabricate a NKN single crystal due to the sodium and potassium. Thus, $(Na,K)NbO_3-Ba(Cu,Nb)O_3$ (NKN-BCuN) is chosen to fabricate the single crystal with relative ease. NKN-BCuN pellets consist of two parts, yellow single crystals and gray poly-crystals that contain copper. The area that has a large amount of copper particles may melt at low temperature but not the other areas. The liquid phase may be responsible for the abnormal grain growth in NKN-BCuN ceramics. The dielectric constant and tan ${\delta}$ are measured to be 684 and 0.036 at 1 kHz in NKN-BCuN, respectively. The coercive field and remnant polarization are 14 kV/cm and $20{\mu}C/cm^2$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.3
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• pp.224-232
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• 1990

This study was conducted to find out the improvement of water-logging injury which is an important factor of yield loss in sesame. Water-logging was treated at 10, 25, 40, 55 and 70 days after emergence for 24, 48 and 72 hours in sesame variety 'Ansanggae'. Some important agronomic characters were investigated after treatment. The important agronomic characters such as plant height, leaf area, dry matter weight, capsule setting stem length, number of capsules per plant, ripenning rate and 1,000 grain weight were most susceptible at 55 days after emergence by the water-logging treatment, and the longer period of water-logging, the more susceptible. Allmost of the useful agronomic characters were able to get over injury of water-logging only within 25days after emergence, but could not get it over since 40days. Grain yield was decreased due to the water-logging treatment by 69 to 86% in 55 days after emergence that is most susceptible stage for water-logging as compared with the untreated control which is 13g per pot, and the longer period of water-logging induced the lower yield. Oil content of grain showed significant decrease only in 55 days after emergence but the composition of fatty acid did not influenced by the water-logging.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.6
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• pp.537-544
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• 1993

Super-giant-embryo mutant line (Hwacheong-ge$^s$) with high nutritional quality was developed from Hwacheongbyeo, a Korean Japonica cultivar. Grain weight of brown rice of Hwacheong-ge$^s$ line was lighter than of Hwacheongbyeo. However, embryo dry weight of the line was 3.22 times heavier than that of Hwacheongbyeo on the single grain base. Hwacheong-ge$^s$ line showed higher protein(8.99%) than the original variety(7.39%), without changes in storage protein. In amino acid composition, lysine content was greatly increased in the mutant, while the contents of methionine, serine and tyrosine were slightly decreased as compared with the original one. Lipid content of Hwacheong-ge$^s$ line was 1.5 times higher compared with that of Hwacheongbyeo. The contents of Vitamin Bl, B2, and E(${\alpha}$-tocopherol) were also greatly increased in Hwacheong-ge$^s$line. The grain yields of the mutant lines ranged from 69.2% to 78.8% compared with that of Hwacheongbyeo, 556kg /10a. Most of the mutant lines of M4 generation were homogeneous for growth characters, and some of them seemed to be readily applicable for farmer's field.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.3
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• pp.286-294
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• 2008

In order to understand the physical properties of deep-sea sediments, which mainly consist of pelagic red clays, sediment samples were collected at 24 stations using a multiple corer in the Clarion-Clipperton fracture zone of the northeast equatorial Pacific. The sampled sediment cores were examined for the mass physical properties(i.e. grain size distribution, mean grain size, water content, specific grain density, wet bulk density, void ratio, and porosity) and the geotechnical properties(i.e. shear strength and consistency limits) with the content of biogenic opal and mineral composition. Although KR1 and KR2 areas on the same latitude are logitudinally far from each other, the mass physical properties of these areas are not distinctly different except for shear strengths. The maximum shear strength of surface sediments in KR2 area is higher than that in KR1 due to the appearance of a consolidated lower layer(Unit 3) in the sediment core from KR2.