• 한국세라믹학회지
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• 제35권12호
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• pp.1294-1300
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• 1998

Yttria-stabilized zirconia ceramics with irregular grain shapes and curved grain boundaries was prepared by ceria doping. The amount of ceria doped into zirconia compacts by a dipping method were at range of 2 to 20 mol% Irregular grain shapes and curved grain boundaries were formed only inspecimens doped with more than 8mol% cerial. Ceria-doped specimens showed large grain size and low sintered density compared with pure yttria-stabilized zirconia which was due to the increase in the contents of stabilizer and cubic phase. The amount of doped ceria was larger on the surface than the inside regions and therefore mi-crostructure and phase on the surface were different from those in the inside regions. Transgranular frac-ture mode was observed ion ceria doped specimens due to irregular large grain sizes.

• Current Research on Agriculture and Life Sciences
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• 제14권
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• pp.37-47
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• 1996

The main objectives of this studies are to present the most desirable rice processing complex model system in a given our situations by comparision and analyzing the major factors and, also recommend the future prospect of the rice processing complex in Korea. There are 3 different rice processing complex models in Korea. Those are concrete bin, flat type steel bin and square bin. These systems have a lot of differences and have their own characteristics such as capital requirement, efficiency, storage capacity and quality controls. The major problems of the existing rice processing centers in Korea are high fixed cost and the unbalnced systems. Following is summary to solve this problems: 1. Development of the large scale harvester and high speed continuous dryer. 2. Quality inspective system of bulk grain and large scale temporary storage facilities. 3. Large size readjustment of arable land. 4. Select the convenient location of rice processing center and formulation of well equipment facilities.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.329-329
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• 2016

Large-area graphene films produced by means of chemical vapor deposition (CVD) are polycrystalline and thus contain numerous grain boundaries that can greatly degrade their performance and produce inhomogeneous properties. A better grain boundary engineering in CVD graphene is essential to realize the full potential of graphene in large-scale applications. Here, we report a defect-selective atomic layer deposition (ALD) for stitching grain boundaries of CVD graphene with ZnO so as to increase the connectivity between grains. In the present ALD process, ZnO with hexagonal wurtzite structure was selectively grown mainly on the defect-rich grain boundaries to produce ZnO-stitched CVD graphene with well-connected grains. For the CVD graphene film after ZnO stitching, the inter-grain mobility is notably improved with only a little change in free carrier density. We also demonstrate how ZnO-stitched CVD graphene can be successfully integrated into wafer-scale arrays of top-gated field effect transistors on 4-inch Si and polymer substrates, revealing remarkable device-to-device uniformity.

• 비파괴검사학회지
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• 제7권2호
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• pp.8-15
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• 1988

A split-spectrum processing technique for an ultrasonic flaw detection system has been developed, which improves the flaw-to-grain echo ratio in large-grained materials. The enhancement is achieved by partitioning a wide-band received spectrum to obtain frequency shifted bands, which are then processed to suppress the grain echoes with respect to the flaw echo, using a novel signal minimization algorithm. A technique for suppression of grain echoes has also been devised which takes advantage of the fact that the grain echo amplitude changes with the frequency of the incident ultrasound whereas the flaw echo amplitude does not. The combination of this technique and the new flaw detection system greatly improve the capabilities of ultrasonic evaluation of large grain materials.

• 소성∙가공
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• 제21권5호
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• pp.324-329
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• 2012

Mg-(9-x)Sn-xAl-1Zn (x=1, 2, 3 and 4 wt.%) alloys were subjected to indirect extrusion, and the microstructure and mechanical properties of the as-extruded Mg-Sn-Al-Zn (TAZ) alloys were investigated. The TAZ 811 alloy exhibited a finer grain structure than the TAZ 541 alloy due to a larger number of Mg2Sn particles, which pinned the grain boundaries and prevented growth of recrystallized grains. The TAZ alloys showed an unusual yield asymmetry behavior. The tension-compression yield asymmetry increased with decreasing average grain size. The TAZ 811 alloy with a small grain size exhibited a larger yield asymmetry than that of the TAZ 541 alloy having a relatively large grain size, which is mainly attributed to the low Al content and large number of second phase particles in the TAZ 811 alloy.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.429-429
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• 2010

TFT 제조 방법 중 LTPS (Low Temperature Polycrystalline Silicon)는 저온과 저비용 등의 이점으로 인하여 flat panel display 제작에 널리 사용된다. 이동도와 전류 점멸비 등에서 이점을 가지는 ELA(Excimer Laser Annealing)가 널리 사용되고 있지만, 이 방법은 uniformity 등의 문제점을 가지고 있다. 이를 극복하기 위한 방법으로 MICC(Metal Induced Capping Crystallization)이 사용되고 있다. 이 방법은 $SiN_x$, $SiO_2$, SiON등의 capping layer를 diffusion barrier로 위치시키고, Ni 등의 금속을 capping layer에 도핑 한 뒤, 다시 한번 열처리를 통하여 a-Si에 Ni을 확산시키킨다. a-Si 층에 도달한 Ni들이 seed로 작용하여 Grain size가 매우 큰 film을 제작할 수 있다. 채널의 grain size가 클 경우 grain boundary에 의한 캐리어 scattering을 줄일 수 있기 때문에 MIC 방법을 사용하였음에도 ELA에 버금가는 소자의 성능과 안정성을 얻을 수있었다. 본 연구에서는 large grain TFT의 Gate bias stress에 따른 소자의 안정성 측정 및 분석에 목표를 두었다.

• 한국초전도ㆍ저온공학회논문지
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• 제20권3호
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• pp.5-10
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• 2018

This study presents that various grain boundary junctions are prepared by controlling the seed orientation combined with an artificial hole in a melt process REBCO bulk superconductor. Large grain YBCO superconductors have been fabricated with various grain boundary junctions that the angle between the grain boundary and the <001> axis of Y123 crystal is $0^{\circ}$, $30^{\circ}$ and $45^{\circ}$, respectively. The presence of the artificial hole is beneficial for the formation of clean grain boundary junction and single peak trapped magnetic field profiles have been obtained. Artificial hole makes two growth fronts meet at a point on a periphery of the artificial hole. The presence of artificial hole is not likely to affect on the distribution of Y211 particles. The newly formed <110> facet lines are explained by the formation of new Y123/liquid interface with (010) crystallographic plane.

• 한국작물학회지
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• 제40권5호
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• pp.655-661
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• 1995

대립벼의 생육특성 및 등숙저하 원인을 구명하고자 탐진벼와 장간대립임 SR7796F$_{7}$, 단간대립인 SR11269F$_{6}$를 6월4일 이앙하여 물질생산능력과 생산구조의 차이 및 수량성을 검토한 결과는 다음과 같다. 1. 엽면적지수는 탐진벼, SR11269F$_{6}$, SR7796F$_{7}$순으로 높았으며, 출수20일이후부터 엽면적 감소는 대립벼가 탐진벼보다 컸다. 2. 지상부 총건물중은 SR11269F$_{6}$, 탐진벼, SR7796F$_{7}$순으로 많았다. 출수율 대비 성숙기의 경의 건물중이 탐진벼는 15%, SR11269F$_{6}$은 2%감소하였으나, SR7796F$_{7}$은 5% 증가하였다. 등숙기간중 이삭무게 증가는 대립벼가 탐진벼보다 등숙초기에는 많았고 등숙후기에는 적었다. 3. 총건물중에 대한 각 기관별 분배율을 보면 엽신의 비율은 대립벼가 탐진벼보다 적었고 그 차이는 출수기 이후에 더욱 컸다. 그러나, 수수기 경의 분배율은 탐진벼는 36%인 반면 SR7796F$_{7}$은 38%, SR11269F$_{6}$는 41%로 대립벼에서 많았다. 4. 최대엽신분포부위는 지상부로부터 탐진벼는 40~50cm, SR11269F$_{6}$는 30~40cm, SR7796F$_{7}$은 70~80cm였으며, 수수분포 절위는 탐진벼는 40cm, 대립벼는 70cm로 대립벼에서 컸다. 5. 대립벼는 탐진벼보다 단위면적당 광합성속도가 낮았으며 등숙비율이 현저히 낮아 결과적으로 수량도 낮았다. 이상의 결과로 보아 대립벼의 등숙향상을 위해서는 생육기간중 엽면적 확보와 아울러 이를 생육후기까지 유지시킬 수 있는 재배법 개발이 요구되며 주내의 생육을 균일하게 하는 것이 중요하다고 생각된다. 중요하다고 생각된다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.126-127
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• 2006

In this study, nano grain W is fabricated by Severe Plastic Deformation-Powder Metallurgy (SPD-PM) process. W powder and W-Re powder mixtures are processed by SPD-PM process, a Mechanical Milling (MM) process. As results, a nano grain structure, whose grain size is approximately 20nm, is obtained in W powder after MM for 360ks. A nano grain W compact, whose grain size 630nm, has excellent deformability above 1273K. A nano grain W-10Re compact is composed of equiaxed grain, a grain growth is restrained and has low dislocation density after the large deformation; therefore it is considered that W-Re compact shows superplasticity.

• 한국전기전자재료학회논문지
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• 제16권12호
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• pp.1131-1135
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• 2003

In the sintering of YIG, abnormal grain growth phenomena were observed. This abnormal grain growth is related to the sintering temperature in this experiment. In the sintering below 1450$^{\circ}C$, the sintered body showed narrow size distribution. However, in the sintering at 1450$^{\circ}C$, a few grains grew rapidly with respect to other grains, and bimodal size distribution was appeared. From the observation of the microstructure, liquid phase was not observed far from the abnormally grown large grains, but only near the large grains. This means that the abnormal grain growth was caused by the nonuniform distribution of liquid phase which promote the grains growth. Because the growth rate of grains near the liquid phase is much higher than that of the other grains, a few grains grow rapidly. This nonuniform distribution of liquid phase was thought to be due to the nonuniform mixing of the calcined powders. This abnormal grain growth was suppressed by enhancement of the compositional uniformity by multiple calcination.