• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.228-230
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• 2004

Samples of the aluminum alloy 3103 sheets were repeatedly deformed by ECAR up to twelve passes. Shear textures developed after the first passage of ECAR. However, the intensity of shear texture components decreased with increasing number of ECAR passages. Observations by TEM and EBSD revealed that the degree of misorientations within the deformed grains increased with increasing number of ECAR passes. Changes in textures and microstructures were hardly observed during recrystallization anneal. Upon subsequent annealing, the samples deformed by a large number of ECAR passes displayed a continuous grain growth. A higher deformation by ECAR resulted in a slower softening, which reflects the stability of ultra-fine grains against the grain growth.

• Interaction and multiscale mechanics
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• 제4권3호
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• pp.207-217
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• 2011

International efforts have focused recently on the development of tungsten surfaces that can intercept energetic ionized and neutral atoms, and heat fluxes in the divertor region of magnetic fusion confinement devices. The combination of transient heating and local swelling due to implanted helium and hydrogen atoms has been experimentally shown to lead to severe surface and sub-surface damage. We present here a computational model to determine the relationship between the thermo-mechanical loading conditions, and the onset of damage and failure of tungsten surfaces. The model is based on thermo-elasticity, coupled with a grain boundary damage mode that includes contact cohesive elements for grain boundary sliding and fracture. This mechanics model is also coupled with a transient heat conduction model for temperature distributions following rapid thermal pulses. Results of the computational model are compared to experiments on tungsten bombarded with energetic helium and deuterium particle fluxes.

• 한국자원식물학회지
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• 제11권2호
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• pp.146-151
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• 1998

A study was carried our to investigate the characteristics of physico-chemical components palatability of cooked rice accoring to different transplanting time. The treatments were consisted of five transplanting time, from May 5 to July 5 at 15 -day intervals, and six cultivars ; two early-maturing, two mid-maturing and two late-maturing cultivars which are clearly identified by evaluation of cumulative temperature and growth duration from seeding to heading of rice plants. In gelatinization characteristics of rice grain, alkali digestion value was low in the earlier transplanting regardlessof maturing types. Initial pasting temeprature maximum viscosity and breakdown as amylogram charcteristics were high at the transplanting of June 5. The palatability of cookedrice was evaluated that early-maturing cultivars were much better in early transplanting than in late transplanting . The optimum transplanting time for palatibility was the periods from May 5 to 20 in early maturing varieties, May 20 to June 5 in mid-maturing and June 5 to June 20 in late-maturing ones at Honam district in Korea.

• 자연과학논문집
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• 제5권1호
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• pp.15-28
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• 1992

토양에 20년간 3요소+생고를 처리하였을때 토양의 화학적 성분, 공극율, 입단구조가 잘 발달되었다. 또한 이 처리에 의하여 CGR은 영화분화기때 가장 높았으나 무처리구나 3요소단용구에서는 전생육기간을 통하여 계속 증가하는 경향을 띈 반면 3요소+생고처리구에서는 영화분화기이후 계속 감소 하는 추세을 나타내고 있다. 현미수량에 있어서는 3요소+생고처리에 의하여 11%의 증가효과가 있었으며 이것은 주로 이삭의 일.이차기경의 분화수가 증가하였기 때문이었다. 또한 미립형태에 있어서도 완전미의 비율이 높았는데 이것은 등숙속도와 매우 밀접한 관계가 있어서 등숙속도가 빠를수록 심백미, 복백미 및 동할미가 많았다. 3요소 + 생고속도는 40DAH이었다.

• 한국작물학회지
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• 제49권2호
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• pp.136-140
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• 2004

Twenty-one lowland rice genotypes were evaluated for their stability parameters with respect to grain yield in a multi locational trial at five different sites of Eastern India viz. CRRI, Cuttack (Orissa); OUAT, Bhubaneswar (Orissa); CRS, Masodha (UP); RAU, Pusa (Bihar) and RARS, North Lakhimpur (Assam). Pooled analysis of variance reflects existence of genotype x environment interactions and contribution of both linear and nonlinear components to genotype (G) x environment (E) interactions. Through stability parameter analysis it was found that Rayda $\textrm{B}_3$, CR 778-95 and CR 661-236 were suitable for over all environments where as Sabita, OR 1334-16 and OR 1358-RGA-4 were suitable for rich environments. PSR 1209-2-3-2, CR 780-1937, Ambika, OR 877-ST-4-2 and CR 662-2211 were identified for poor environments.

• 한국작물학회지
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• 제21권2호
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• pp.250-257
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• 1976

재식밀도를 달리한 조건에서 적엽처리가 대두품종의 수량 및 수량구성요소에 미치는 영향을 알고저 6월1일과 6월20일에 $\textrm{m}^2$당 80본, 40본, 27본 및 20본이 되도록 재식밀도를 조절 파종하고 개화시기에 잔여엽수가 상부로부터 각각 1,2,3,5,7엽이 되도록 하위엽을 적엽처리하고 무적엽의 표준구를 포함하는 6처이로 하여 시험을 실시하였는데 그 결과를 요약하면 다음과 같다. 1. 표준구에서의 최적엽면적지수는 파종기에 따라 다르며 광교에 있어서는 개화시에 LAI가 4~5이고 개화후 30일에는 5~6이었으며 SRF-300에 있어서는 개화시에 2.5~6.0이고 개화 30일후에는 6~7이었다. 2. 종실수량은 재식밀도가 낮은 경우에는 적엽처리에 의하여 직선적으로 감소되었으나 재식밀도가 $\textrm{m}^2$당 40본이상으로 높은 경우에는 수량과 착엽수사이에 유의적인 곡선효과가 인정되어 하위부의 경미한 적엽처리를 하므로서 표준에 비하여 광교에서는 25~35%, SRF-300에서는 13~32%의 증수를 보였다. 3. 적엽처리시에 수량에 가장 크게 영향하는 수량구성요소는 전체적으로 볼때 식물체당 협수이며 다음으로 6월1일 파종구에서 재식밀도가 감소됨에 따라서 광교에서는 립중의 효과가 증대되었고 SRF-300에서는 수량에 영향하는 임실율의 비중이 현저히 증대되었다.

• 한국재료학회지
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• 제33권10호
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• pp.393-399
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• 2023

In this study, changes in the microstructure and mechanical properties of cast and extruded Al-2Li-1Ce alloy materials were investigated as the Mg content was varied. The density decreased to 2.485, 2.46 and 2.435 g/cm³ when the Mg content in the Al-2Li-1Ce alloy was increased to 2, 4 and 6 wt%, respectively. Intermetallic compounds of Al₁₁Ce₃ were observed in all alloys, while the β-phase of Al₃Mg₂ was observed in alloys containing 6 wt% of Mg. In the extruded material, with increasing Mg content the average grain size decreased to 84.8, 71.6 and 36.2 ㎛, and the fraction of high-angle grain boundaries (greater than 15°) increased to 82.8 %, 88.6 %, and 91.8 %, respectively. This occurred because the increased Mg content promotes dynamic recrystallization during hot extrusion. Tensile test results showed that as the Mg content increased, both the yield strength and tensile strength increased. The yield strength reached 86.1, 107.3, and 186.4 MPa, and the tensile strength reached 215.2, 285, and 360.5 MPa, respectively. However, it is worth noting that the ductility decreased to 27.78 %, 25.65 %, and 20.72 % as the Mg content increased. This reduction in ductility is attributed to the strengthening effect resulting from the increased amount of dissolved Mg, and grain refinement due to dynamic recrystallization.

• 한국농림기상학회지
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• 제17권2호
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• pp.156-164
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• 2015

기후변화로 야기되는 미래의 고온 환경은 벼의 생산성을 저하시킬 것으로 예측되고 있다. 본 연구에서는 기후변화에 따른 국내 벼 생산성의 신뢰성 있는 영향평가 기초자료를 확보하기 위해 고온 환경에서의 벼의 수량과 수량 구성 요소의 반응을 조사하고 분석하였다. 실험은 1/5000a 와그너 포트를 이용하여 2008년과 2009년에 걸쳐 서울대학교 부속실험농장($37^{\circ}16^{\prime}N$, $128^{\circ}59^{\prime}E$)의 온도조절 플라스틱 하우스에서 실시되었다. 2008년에는 자포니카계의 화성벼를 공시품종으로 이용하였으며, 시비수준을 $120kg\;N\;ha^{-1}$와 $180kg\;N\;ha^{-1}$로 하였다. 온도처리는 대기온도, 대기온도 대비 $+1.5^{\circ}C$, $+3.0^{\circ}C$의 세 수준으로 하였다. 2009년에는 화성벼와 통일계의 다산벼를 공시품종으로 하여 $120kg\;N\;ha^{-1}$ 수준으로 시비하였다. 온도처리는 대기온도, 대기온도 대비 $+1.5^{\circ}C$, $+3.0^{\circ}C$ 및 $+5.0^{\circ}C$ 수준으로 처리하였다. 수량 및 수량구성요소의 온도처리에 따른 영향은 품종별로 상이한 반응을 보였다. 이삭수와 이삭당 영화수는 두 품종 모두 온도처리의 영향을 받지 않았으나, 천립중과 등숙률에 대해 화성벼는 $5.0^{\circ}C$, 다산벼는 $1.5^{\circ}C$ 이상의 온도처리에서 유의하게 감소하였다. 포트당 수량은 화성벼의 경우 $5.0^{\circ}C$, 다산벼는 $3.0^{\circ}C$ 및 $5.0^{\circ}C$ 온도처리에서 유의한 감소를 나타냈다. 등숙기간 동안의 평균기온에 대한 천립중과 등숙률 반응 또한 품종별로 다르게 나타났다. 다산벼의 경우 $23^{\circ}C$ 이상의 평균 온도에 대해 등숙률과 천립중이 급격히 감소한데 반해, 화성벼는 $23^{\circ}C$부터 $27^{\circ}C$ 범위에 대해 등숙률과 천립중의 변화가 크지 않았다. 기후변화에 의한 지속적인 기온상승이 예상되는 가운데 온도상승에 따른 등숙률과 천립중의 감소는 미래 기후 환경에서의 벼의 수량 감소를 야기하는 주요 원인으로 예측된다. 다만, 상승된 기온에 대한 벼의 반응은 품종별로 상이하기 때문에 고온에 둔감한 품종의 도입 또는 그러한 특성을 지닌 품종의 육종을 통해 기후변화에 따른 수량 감소의 위험을 낮출 수 있을 것이다.

• ETRI Journal
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• 제31권6호
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• pp.636-641
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• 2009

ZnO nanofibers were electro-spun from a solution containing poly 4-vinyl phenol and Zn acetate dihydrate. The calcination process of the ZnO/PVP composite nanofibers brought forth a random network of polycrystalline wurtzite ZnO nanofibers of 30 nm to 70 nm in diameter. The electrical properties of the ZnO nanofibers were governed by the grain boundaries. To investigate possible applications of the ZnO nanofibers, their CO and $NO_2$ gas sensing responses are demonstrated. In particular, the $SnO_2$-deposited ZnO nanofibers exhibit a remarkable gas sensing response to $NO_2$ gas as low as 400 ppb. Oxide nanofibers emerge as a new proposition for oxide-based gas sensors.

• 마이크로전자및패키징학회지
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• 제24권3호
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• pp.77-81
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• 2017

Pulse electroplating of Ni-P alloy was studied to fulfill the material requirement to the advanced vertical probe tip in wafer probe card. The major concerns are for the electrical conductivity and yield strength. Plating parameters such as current density, duty cycle and solution components were examined to obtain the nanocrystal structure and proper percentage of phosphorus, leading to how to control the nanocrystal grain growth and precipitation of $Ni_3P$ after heat treatment. Among the parameters, the amount of phosphorus acid was the main factor affecting on the grain size and sheet resistance, and the amount of 0.1 gram was appropriate. Since hardness in Ni-P alloy is increased by as-plated nanocrystal structure plus precipitation of $Ni_3P$, the concentration of P less than 15 at% was better choice for the grain coarsening without minus in hardness value. The following heat treatment made grain growth and dispersion of precipitates adjustable to meet the target limit of resistance of $100m{\Omega}$ and hardness number of over 1000Hv. The Ni-P alloy will be a candidate for the substitute of the conventional probe tip material.