• Journal of Ceramic Processing Research
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• 제20권1호
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• pp.59-62
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• 2019

Y2O3-MgO nanocomposites are promising materials for hypersonic infrared windows and domes due to their excellent midIR transmittance and mechanical properties. In this work, influence of SPS heating rate on the microstructure, IR transmittance, and mechanical properties of Y2O3-MgO nanocomposites was investigated. It was found that the average grain size decreases with a decreasing heating rate, which can be attributed to high defect concentration by rapid heating and deformation during densification. Also, the residual porosity decreases with a decreasing heating rate, which is ascribed to the enhancement of grain boundary diffusion by a large grain-boundary area (a small grain size). Consequently, high transmittance and hardness were attained by the low heating rate. On the other hand, the mechanical strength showed little difference with the heating rate change, which is somewhat different from the general knowledge on ceramics and will be discussed in this letter.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1999년도 동계 학술대회 논문집
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• pp.476-483
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• 1999

• 한국작물학회지
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• 제33권3호
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• pp.262-269
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• 1988

벼의 등숙기간중에 발생하는 수발아 피해를 경감시킬 수 있는 방법을 모색하기 위하여 품종간 수발아성 비교, 출수후 종자발달에 따른 발아율 비교, 등숙기의 생장조절제 처리가 수발아에 미치는 영향 등을 조사 및 실험한 결과를 요약하면 다음과 같다. 1. 보통기 보비 재배한 포장에서의 수발아성은 일반형중 조생종들이 높았고 중만생종과 통일형 품종들은 수발아가 되지 않았다. 2. 일반형 품종인 대성벼는 출수후 30일, 통일형인 태백벼는 35일이 경과되면 발아력이 높아져 종자로서의 발아조건은 충분히 갖추어진 것으로 보여진다. 3. 공시한 두 품종 및 3처리시기에서 모두 수발아 억제에는 NAA 및 CMH는 100ppm 그리고 Reglone은 0.4∼0.6%의 농도에서 효과가 가장컸다. 4. 생장조절제가 처리된 종자의 발아율은 공시된 두 품종 모두 NAA와 CMH는 무처리와 차이없이 양호 하였으나 Reglone 이 처리된 종자의 발아율은 낮았다. 5. 생장조절제가 처리된 두 품종의 등숙율은 NAA와 CMH는 무처리와 차이가 없었으나 Reglone처리 구는 낮았고 종자 색갈은 NAA만이 무처리와 비슷하였으며 CMH와 Reglone 은 농도가 높아짐에 따라 다갈색을 띄는 미립이 많았다. 도정특성을 보면 NAA는 무처리와 차이가 없었고 CMH 및 Reglone을 출수후 20∼30일에 처리한 구는 완전현미비율이 낮았다.

• 자동차안전학회지
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• 제13권3호
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• pp.20-25
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• 2021

Flexural resistance evaluation of FFC (Flexible Flat Cable) was performed according to the grain size of rolled copper foil by adding 0.1wt% silver (Ag) and electrodeposited copper foil by slitting method after heat-treatment. These methods are aimed at enhancing the flexural durability of the FFC by growing the grain size of copper foil. By increasing the grain size of the copper foil and minimizing the miss-orientation at grain boundaries, the residual stress at the grain boundaries of the copper foil is reduced and the durability of the FFC is improved. Maximizing an average grain size of copper foil can be got a good solution in order to enhance the durability of the FFC or FPCB (Flexible Printed Circuit Board).

• 한국작물학회지
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• 제44권1호
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• pp.86-94
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• 1999

A set of rice recombinant inbred lines was developed from a cross between a Tongil type variety, Nonganbyeo, and an indica variety, BG276, by the single seed descent method. The number of the lines in the population was 272. All the agronomic characters studied except ADV (alkali-digestion value) showed continuous variation among the RILs, implying that their inheritance mode should be quantitative. The patterns of the variation in the RILs were either normal or skewed distribution. ADVs of RILs were segregated into two groups with 1:1 ratio, indicating that ADVs in this KIL population might be controlled by one major gene. Transgressive variations were also observed in all characters. Heritability values of the characters varied from 0.488 in brown/rough rice ratio to 0.895 in alkali-digestion value. In the analysis of genotypic and phenotypic correlations, the character of yield was positively correlated with 8 different agronomic characters. The number of panicles per hill was negatively correlated with culm length, panicle length, and number of spikelets per panicle. Grain length was positively correlated with grain width, grain thickness, grain length/width ratio, white belly, ADV, and amylose. However, grain length/width ratio was negatively correlated with grain width. White core was also negatively correlated with white belly and ADV.

• 한국작물학회지
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• 제60권3호
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• pp.273-281
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• 2015

벼 등숙기간 및 등숙기 기간별 기온과 일조시간이 쌀 품질 특성에 미치는 영향을 알아보기 위하여 전국 8개도 24개 지역에서 고품질 벼 11품종을 이용하여 2013-2014년에 시험한 결과는 다음과 같다. 1. 품종, 지역 및 연차별 시험성적을 모두 합하였을 때, 출수기, 출수 후 40일간 평균기온 및 일조시간의 범위는 각각 7월 23일~9월 4일, $18.8{\sim}26.4^{\circ}C$, 3.9~8.0시간/일이었다. 2. 성적을 모두 합하였을 때, 특성별 범위는 등숙비율 74.2~97.9%, 현미 천립중 19.6~26.1 g, 완전미 비율 61.4~98.5%, 완전미 수량 276~701 kg/10a, 쌀 단백질 4.8~8.3%, Toyo Mido Meter 값 66.1~91.5였다. 3. 완전미 비율, 완전미 수량, 쌀 단백질 및 Toyo Mido Meter 값은 출수 후 40일간의 등숙 최적온도인 $22.6^{\circ}C$보다 낮은 온도에서 높아졌으며, 쌀 외관품위와 밥맛을 고려한 출수 후 40일간의 최적 일조시간은 6.0~6.1시간/일로 평가되었다. 4. 쌀 단백질은 출수 후 40일간의 평균기온 및 일조시간과 유의한 관계를 보인 품종이 전체 11품종 중 각각 8개와 9개로, 다른 특성에 비해 많았다. 5. 쌀 단백질은 등숙 초기의 평균기온 및 등숙 초 중기의 일조시간에, 완전미 비율은 등숙 초기의 평균기온 및 일조시간에 상대적으로 더 큰 영향을 받았다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.92-95
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• 2003

Asymmetric rolling of AA1050 Al alloy sheets was performed to obtain the shear textures for improving the deep drawability and the grain refinement. The effect of roll velocity ratio on the texture and the grain refinement of 50％ asymmetrically rolled sheets was studied. The textures of the asymmetrically rolled sheets after annealing at 400$^{\circ}C$ for 1 h was also investigated.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1993년도 제1회 학술강연회논문집
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• pp.55-61
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• 1993

An experimental investigation was conducted in order to determine the flammability limit of the solid fuel ramjet using the backward facing step flow combustion of the plexiglass grain. In order to get the different step height ratio, the grain was drilled straight forward or stepwise. The Phoenics computer code was adopted in order to compare. the flow patterns of the some sample tests using a non-reacting cold turbulent flow model. The stepwise grain give some loading advantage; specially thin and long shape grain design.

• 비파괴검사학회지
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• 제10권1호
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• pp.18-23
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• 1990

In materials with the large grain size, ultrasonic waves are highly attenuated by the grain boundary acting as scattering centers due to discontinuity of elastic constant. In this study, the improved probes were developed so that they minimized the effect of grain scattering in order to detect deep flaws in coarse grained materials. As the result, the developed ultrasonic transducers showed the better sensitivity and signal to noise ratio when compared with the commercial probes in testing the interior of coarse grained material.

• 한국환경과학회지
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• 제17권11호
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• pp.1203-1210
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• 2008

Flow resistance in a natural stream is caused by complex factors, such as the grains on the bed, vegetation, and bed-form, reach profile. Flow resistance in a generally stable gravel bed stream is due to protrudent grains from bed. Therefore, the flow resistance can be calculated by equivalent roughness in gravel bed stream, but estimation of equivalent roughness is difficult because nonuniform size and irregular arrangement of distributed grain on natural stream bed. In previous study, equivalent roughness is empirically estimated using characteristic grain size. However, application of empirical equation have uncertainty in stream that stream bed characteristic differs. In this study, we developed a model using an analytical method considering grain diameter distribution characteristics of grains on the bed and also taking into account flow resistance acting on each grain. Also, the model consider the protrusion height of grain.