• Geomechanics and Engineering
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• 제1권2호
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• pp.169-178
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• 2009

Due to the enormous amount of fills required, broken rock-fine grain soil mixtures have been increasingly used in the construction of high-fill foundations for airports, railways and highways in the mountain areas of western China. However, the compressibility behavior of those broken rock-fine grain soil mixtures remains unknown, which impose great uncertainties for the performance of those high-fill foundations. In this research, the mixture of broken limestone and a fine grain soil, Douposi soil, is studied. Large oedometer tests have been performed on specimens with different soil content. This research reveals the significant influence of fine grains on the compressibility of the mixture, including immediate settlement, creep, as well as wetting deformation.

• 암석학회지
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• 제23권3호
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• pp.187-195
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• 2014

이 논문에서는 경주시 양남면에 분포하는 해발고도 약 45 m의 수렴단층 노두 해안단구 퇴적층의 형성시기를 추정하기 위하여, 퇴적층을 구성하고 있는 석영에 대한 단일입자 OSL(Single Grain Optically Stimulated Luminescence) 연대측정을 실시하였다. 실험에 사용된 총 1200개의 석영입자 중, 93개의 입자가 연대측정에 적합한 OSL 신호특성을 보였으며, 이들의 등가선량은 50-610 Gy까지 넓은 분포를 보인다. 이 자료를 중심연대모델(Central Age Model)과 최소연대모델(Minimum Age Model)을 이용하여 분석하면, 각각 $83{\pm}4ka$와 $60^{+3}{_{-7}}ka$의 연대가 도출되지만, 이들 연대는 MIS 5a시기로 보고된 기존의 제2해안단구의 OSL 연대와 층서적으로 불일치한다. 단일입자 OSL 분석결과들을 혼합연대모델(Finite Mixture Model)에 적용하면, 분석된 입자들 중 $6{\pm}4%$의 석영입자가 MIS 7의 퇴적시기 $194{\pm}24ka$)를 지시함을 알 수 있다. 결론적으로, 수렴단층 노두 해안단구 퇴적층이 MIS 7 시기에 형성되었을 가능성을 배제할 수 없으며, 이 퇴적층은 일반적으로 적용되는 다입자 OSL(multiple grain OSL) 연대측정법을 적용하기에 적합하지 않은 시료로 판단된다.

• 한국농공학회지
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• 제17권1호
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• pp.3655-3665
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• 1975

This study was intended to develop a method for measuring the grain separating performance of threshers. The grain separating apparatus used for the experiment was designed and constructed, the function of which was to separate pneumatically mature and immature grain, chaff, straw, dust, and other impurities from the products of threshing. The apparatus has five material outlets where grains and impurities are fallen down by separation depending upon the specific gravity of the material white it moves above the outlets. The principle of design was to separate the mixture of mature grain, immature grain and chaff as distinct as possible, and to induce the mature grains onto the first outlet, the immature grains onto the second and the third, and the straw wastes onto the forth and the fifth outlets. The developed apparatus was tested to evaluate its separating performance with two rice varieties (Tongil and Mine-hikari) at different moisture levels and air velocities. The optimum conditions for operating the apparatus were found from experiment. The results are summarized as follows; 1. The degrees of separation, especially the amount of immature grain contained in the mature paddy, were dependent upon air speed delivered. The optimum air velocities for this apparatus for each levels of grain moisture contents were found from a series of experiments as follows; 14.7-15.3m/sec. for grain of 16 percent moisture content in wet basis, 15.3-16.0m/sec. for 20 percent, and 16.0-16.4m/sec for 24 percent. 2. Composition ratios determined based on the brine separating method was fairly well acted upon the developed apparatus, indicating its recollecting rate of the mature grains as 97.6 to 99.9 percent. The developed separatus acted similarly upon the two rice varieties which had different composition of immature paddy grain. In other words, the separating performance by the apparatus had a good correlation with the one by the brine separating method. 3. As immature grains were separated out unsatisfactory in these experiments than the brine separating method, further investigation may be needed to improve a separating performance of these materials. But the results obtained suggested a possibility of using the tester to replace the current hand separating method, ther eby enabling more consistent test results and also eliminating nearly all costly hand seperating operations.

• 세라미스트
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• 제23권2호
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• pp.114-131
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• 2020

Fracture in the titanium carbonitride-metal composites occurs by crack propagation through the carbonitride grains or in the interfaces. Thus, intrinsic properties of the carbonitride need to be enhanced and the interfaces should be also modified to coherent structure to strengthen the composites. Especially, interfacial structure can be the main factor to determine the mechanical properties of titanium carbonitride-metal composites because the interfaces between carbonitride grains and metallic phase are weak parts due to heterogeneous nature of carbonitride and metallic phase. In this paper, methodologies for improving the interfacial structure of titanium carbonitride-metal composites are suggested. Total area of the interfaces can be reduced using solid solution type carbonitrides as raw materials instead of a mixture of various carbonitrides in the composites. Also, synthesis of titanium carbonitride-metal composite powders and the low-temperature sintering of the composite powders for short time can be the way for formation of coherent interfaces. The sintering of the composite powders for short time at low temperature can reduce the potential of formation of interfaces by dissolution and precipitation of carbonitride in the liquid metal. As a result of formation of coherent boundaries due to low-temperature and short-time sintering, interfaces between titanium carbonitride grains and metallic phase have the favorable structure for the enhanced fracture toughness. It is believed that the low-temperature sintering of solid solution type composite powders for short time can be the way to improve the low toughness of the titanium carbonitride-metal composites.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.315-318
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• 2004

We developed a vapor induced crystallization (VIC) process for the first time to obtain high quality polycrystalline Si films by sublimating the mixture of $AlCl_3$ and $NiCl_2$. The VIC process enhanced the crystallization of amorphous silicon thin films. The LPCVD amorphous silicon thin films were completely crystallized after 5 hours at 480 $^{\circ}C$. It is known that needle-like grains with very small width grow in the Ni-metal induced lateral crystallization. In our new method, the width of grains is larger because the grain can also grow perpendicular to the needle growth direction. Also the interface between the merging grain boundaries was coherent. As the results, a polycrystalline film with superior microstructure has been obtained.

• Asian-Australasian Journal of Animal Sciences
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• 제15권9호
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• pp.1307-1311
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• 2002

Twelve dietary combinations were prepared using 70 parts of fermented wheat straw (FWS) as the sole roughage supplemented with 30 parts of either the low protein concentrate mixture (Conc.-I), high protein concentrate mixture (conc.-II), maize grains (M), solvent extracted mustard cake (DMC), deoiled rice bran (DRB), uromol bran mixture (UBM), deep stacked poultry litter (DSPL), dried poultry droppings (DPD), M-DMC mixture (50:50), M-UBM mixture (50:50), M-DPD mixture (50:50) or M-UBM-DPD mixture (50:25:25) and evaluated by in-sacco technique. The above dietary combinations were also evaluated by changing the roughage to concentrate ratio to 60:40. The digestion kinetics for DM and CP revealed that FWS:DPD had the highest, whereas, the FWS:M-DMC had the lowest rapidly soluble fraction. The potentially degradable fraction was found to be maximum in FWS:M and minimum in FWS:DPD dietary combinations. The higher degradation rate of FWS:DRB and FWS:UBM combinations was responsible for their significantly (p<0.05) higher effective degradability as compared to other combinations. The highest undegradable fraction noted in FWS:M-UBM-DPD followed by FWS:DMC was responsible for high rumen fill values. The FWS:DRB, FWS:UBM and FWS:DPD combinations had higher potential for DM intake. The dietary combination with higher concentrate level (60:40) was responsible for higher potentially degradable fraction, which was degraded at a faster rate resulting in significantly higher effective degradability as compared to the corresponding dietary combination with low concentrate level (70:30). The low undegradable fraction in the high concentrate diet was responsible for low rumen fill values, which predicted of high potential for DM intake. Out of 24 dietary combinations, FWS with either of UBM, DRB, DMC, Maize, M-DMC or DPD in 70:30 ratio supplemented with minerals and vitamin A in comparison to conventional feeding practice (roughage and concentrate mixture) could be exploited as complete feed for different categories of ruminants.

• 미생물학회지
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• 제40권1호
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• pp.49-53
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• 2004

보리, 쑥, 다시마, 대두를 재료로 하고 Bacillus licheniformis Bl을 접종하여, 맛과 향이 향상된 청국장을 제조하였다. 본 혼합발효에서 단백질분해효소의 활성은 발효시작 하루만에 최대치에 이르렀으며, 발효시작 2일만에 pH는 8.4까지 증가하였다. 당과 아미노산에 의해 생성되는 갈변물질은 초기에 비해 20배 이상 증가하였다. 이상으로 대두에 보리, 쑥, 다시마를 혼합하여도 청국장 제조가 가능함을 확인할 수 있었다. Ethanol과 methanol에 녹인 혼합 발효분말의 농도를 각각 0.2에서 1%(w/v)로 증가시킬수록 농도의존적으로 항산화도는 증가하였다. 항산화도는 1,1-diphenyl-2-picrylhydrazyl (DPPH)를 이용하여 결정하였다. Methanol에 1%의 분말청국장을 녹였을 때 항산화도가 가장 높았다. 고혈압군이 본 혼합 발효분말 20 g을 복용했을 때 수축기 혈압이 2시간 지나 10 mmHg 떨어지는 강하효과가 있었다. 또한 맛과 향의 선호도면에서 보리, 쑥, 다시마가 포함된 혼합 발효분말이 발효대두보다 t검정으로 유의적으로 높음을 보였다. 혼합 발효분말은 앞으로 혈압강하용 기능성 청국장으로 개발될 수 있을 것이다.

• 소성∙가공
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• 제13권5호
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• pp.449-454
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• 2004

The annealing behavior of a 5083 Al alloy deformed at cryogenic temperature was investigated, focusing on the evolution of microstructures and mechanical properties. Especially, the effects of annealing temperature, $150~300^{\circ}C$, and time, 3∼60min., on microstructures and mechanical properties of the sheets received 85% reduction at cryogenic temperature were investigated. The optimization of the annealing conditions resulted in a mixture of equiaxed grains and elongated subgrains, exhibiting a good combination of uniform elongation and high strength.

• 한국세라믹학회지
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• 제50권6호
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• pp.429-433
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• 2013

Silicon, carbon, and B4C powders were used as raw materials for the fabrication of porous SiC. ${\beta}$-SiC was synthesized at $1500^{\circ}C$ in an Ar atmosphere from a silicon and carbon mixture. The synthesized powders were pressed into disk shapes and then heated at $2100^{\circ}C$. ${\beta}$-SiC particles transformed to ${\alpha}$-SiC at over $1900^{\circ}C$, and rapid grain growth of ${\alpha}$-SiC subsequently occurred and a porous structure with elongated plate-type grains was formed. The mechanism of this rapid grain growth is thought to be an evaporation-condensation reaction. The mechanical properties of the fabricated porous SiC were investigated and discussed.

• 한국분말재료학회지
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• 제8권1호
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• pp.35-41
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• 2001

$BaTiO_3$ fine powder was synthesized by hydrothermal process from the mixture of titania-hydroxide($TiO_2{\cdot}xH_2O$) and barium hexa-hydroxide ($Ba(OH)_2{\cdot}8H_2O$) as starting materials. Fine powder(< 100 nm) was made under the reaction conditions of 18$0^{\circ}C$,10 atm, 1.5 hr in autoclave and showed cubic structure. The powders were sintered by a spark plasma sintering technique from 1050~115$0^{\circ}C$ for 5 min. The grains of sample sintered at 110$0^{\circ}C$ were about 0.9${\mu}m$ in average size and showed the mixture of cubic and tetragonal structures.