• 한국재료학회지
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• 제15권9호
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• pp.577-584
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• 2005

Thin Ni-B layer, $1{\mu}m$ thick, was electrolessly deposited on Cu electrode fabricated by electro-deposition. The purpose of the layer is to encapsulate Cu electrodes for preventing Cu oxidation and to serve as a diffusion barrier. The layers were annealed at $580^{\circ}C$ with and without pre-annealing at $300^{\circ}C$ for . 30minutes. In the layer with pre-annealing, the amount of Cu diffusion was lower about 5 times than the layer without pre-annealing. The difference in Cu concentration may be attributed to $Ni_3B$ formation prior to Cu diffusion. However, the difference in Cu concentration decreased during the annealing time of 5 h due to the grain growth of Ni.

• 한국재료학회지
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• 제18권2호
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• pp.107-111
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• 2008

[ $BaO{\cdot}Nd_2O_3{\cdot}5TiO_2$ ] (BNT) ceramics modified with a borate glass containing Ba, Nd and Ti as glass constituents were investigated with regard to their sintering behavior and microwave dielectric properties. An addition of iso-component glass significantly improved the sinterabilty of the BNT ceramics and lowered the sintering temperature. A maximum density of $5.29\;g/cm^3$ and an x-y shrinkage of 17% were obtained for BNT ceramics containing 10wt.% of the glass sintered at $1100^{\circ}C$. The dielectric composition without the glass additive was only slightly densified at $1100^{\circ}C$. The resulting sample exhibited two crystalline phases, $BaNd_2Ti_5O_{14}$ and $Ba_2Ti_9O_{20}$, regardless of sintering temperature and glass content. When >10wt.% glass was added, exaggerated grain growth with a less uniform microstructure was found, resulting in the subsequent reduction of the fired density and the dielectric properties. BNT ceramics containing 10wt.% of the isocomponent glass sintered at $1100^{\circ}C$ for 4 h showed promising dielectric properties of k = 71.3 and Q = 1,330.

• 수산해양기술연구
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• 제31권3호
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• pp.279-286
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• 1995

As Al-Li based alloys are to find widespread use in aerospace and other structural applications in which their low-density high specific stiffness properties be exploited, their mechanical properties must adequately match those of the which they intended to replace. In order to develop these purposed, the precipitation behaviors of the rapidly solidified Al-Li-Ti alloys aged at various temperature were investigated. ${\delta}'$ phase precipitated homogeneously in the matrix during not only melt quenching but also aging at the aging temperature of $160^{\circ}C\;and\;210^{\circ}C$. The addition of the Ti in Al-Li alloy promoted the formation of $\delta$' phase. The addition of Ti on the ${\delta}'$ solvus line had a little effect over the thermodynamics ${\delta}'$ solvus line. The reason for these behavior was that the ${\delta}'$ phase was suppressed to precipitate as much as supercooling by melt quenching. The discontinuous precipitation reaction occurred by the preferential growth of ${\delta}'$ phase due to the migration of grain boundary provided the driving force dependent of solute concentration fluctuations.

• 한국작물학회지
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• 제48권6호
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• pp.473-478
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• 2003

오리농법에 있어서 오리 주간방사에 대한 유효성을 명확히 구명하고자, 오리를 주간 12시간 (07:00-19:00) 논 방사후 야간에는 간이휴식장으로 재수용하는 주간방사구와 주야 24시간 연속방사하는 종일방사구의 2 시험구로 구분하고, 논 방사시간에 따른 오리의 성장과 행동유형, 관개수의 pH 및 용존산소농도, 벼 생육과 수량성에 대하여 검토한 결과를 요약하면 다음과 같다. 1. 오리 방사시간에 따른 오리의 체중은 주간방사구와 종일 방사구간에 큰 차이는 없었으며, 오리 행동유형에서 논내 채식행동과 날개다듬기 행동 및 노동행동은 주간방사구에서 현저하게 증가하였다. 2.주간 12시간(07:00-19:00)동안 오리의 논내 체류시간은 두 시험구간에 거의 유사한 수준을 보였고, 주간방사구 오리의 1일 논내 총 체류시간은 종일방사구 오리의 1/3정도인 것으로 나타났다. 3. 관개수의 pH와 용존산소농도는 종일방사구보다 주간방사 구에서 다소 높은 값을 보였지만, 시험구간에 유의적인 차이는 없었다. 4. 벼 초장은 오리방사 1개월 이후 종일방사구에서 유의적으로 길게 나타났고, 분얼수는 오리방사초기에서 종료시까지 종일방사구에서 현저한 증가를 보였다. 5. 벼 지상부의 건물중량은 출수기에 종일방사구에서 유의적인 증가를 보인 반면, 뿌리의 건물중량은 어느 생육단계에 있어서도 시험구간에 큰 차이가 없었다. 6. 벼 수량성에 있어서, 영화수는 종일방사구에서 현저하게 증가한 반면, 방숙율은 주간방사구에서 유의적으로 높게 나타났다. 그러나 10a당 벼 정조수량은 시험구간에 큰 차이가 없었다. 이상의 결과를 종합해 볼 때, 오리 방사시간은 오리성장과 관개수의 pH 및 용존산소농도 변화에 유의한 영향을 미치지 않았으나, 주간방사구 오리의 논내 채식과 노동행동은 현저한 증가를 보였다. 또한 오리 방사시간에 따른 벼 초장, 분얼수, 영화수 및 등숙율의 변화를 볼 수 있었으나, 정조수량에는 영향을 미치지 않는 것으로 사료되었다. 따라서, 주간 12시간 논 방사하는 오리의 주간방사는 종일방사와 거의 유사한 효과가 있음이 시사되었다.

• 한국수소및신에너지학회논문집
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• 제23권6호
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• pp.670-677
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• 2012

Perovskite-type oxides such as doped barium zirconate ($BaZrO_3$) show high proton conductivity and chemical stability when they are exposed to hydrogen and water vapour containing atmospheres, thus it can be applicable to the hydrogen separation and the fuel cell electrolyte membranes. However the high temperature ($1700-1800^{\circ}C$) and long sintering times (24h) are generally required to prepare the fully densified $BaZrO_3$ pellets. These sintering conditions lead to the limitation of the grain size growth and the degradation of conductivity due to the acceleration of BaO evaporation at $1200^{\circ}C$. Here we demonstrate NiO-doped $BaZr_{0.85}Y_{0.15}O_{3-{\delta}}$ with lower calcination and sintering temperature, less experimental procedure and lower process cost than the conventional mixing method. The stoichiometry of $BaZr_{0.85}Y_{0.15}O_{3-{\delta}}$ was optimized by the control of excess amount of Ba (5mol%) to minimized BaO evaporation. We found that the crystal size of NiO-doped $BaZr_{0.85}Y_{0.15}O_{3-{\delta}}$ was increased with increase of calcination temperature from XRD analysis. NiO-doped $BaZr_{0.85}Y_{0.15}O_{3-{\delta}}$ powder was calcined at $1000^{\circ}C$ for 12h when its showed the highest conductivity of $3.3{\times}10^{-2}s/cm$.

• 대한한방소아과학회지
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• 제13권2호
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• pp.1-39
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• 1999

A infancy is the period in that growth and development of man are the most fast and neutrial requirement is the most big on his life. The insufficient neutrition of this period can have bad effect uppon man's whole life health not only physically but also pscychogenically and emotionally. Therefore a proper feeding at a proper time is very important to form the good food behavior and emotional development. The rate of using the commercial weaning food in Korea has gradually increased since 1970 and expected to be more increasing in future. In this paper, I investigate the general weaning status, stneutrial component and material content of infant weaning foods marketing in Korea at present. The material for this study have been collected in the exposition of products and data from manufacturing companies and etc. The conclusion is following. 1. The proper weaning period is from $4{\sim}6$ momth to 12 momth, but recently it is inclined to prolong. 2. In weaning methods, using a spoon is superior to using a bottle in food behavior and neutrial status. 3. The commercial weaning foods have two type, the powder type and formula type, but except gober's, all products marketing in Korea are the powder type and a sort of product is very simple. Therefore it is necessary to develp the more various kind of weaning foods, especially the formula type. 4. In the neutrial component, Son-Sik (flour of grain) cannot be up to international standards and the greater parts of weaning foods have too much suger over the standards.

• 한국전기전자재료학회논문지
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• 제16권11호
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• pp.979-986
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• 2003

Sintering behavior and electrical properties of CeO$_2$ system were investigated as a function of the amount of Gd:$_2$O$_3$, and Sm$_2$O$_3$, addition. Doped CeO$_2$ consisted of a homogeneous solid solution of the cubic fluorite structure within the amount of addition from 0 mol% to 15 mol%. Grain growth rate of Gd$_2$O$_3$-doped CeO$_2$ was much smaller than that of pure CeO$_2$, while densification rate was considerably larger. Thus doped CeO$_2$ showed a higher density than pure CeO$_2$. The electrical conductivity of Ce$_1$-$_{x}$Sm$_{x}$O$_1$-$_{x}$/2 was increased up to x = 0.2. However, with further increasing dopant concentrations, the magnitude of the conductivity was found to decrease remarkably. The ionic conductivity value obtained at $700^{\circ}C$ for 10 mol% Sm$_2$O$_3$-doped CeO$_2$ electrolyte was 4.6${\times}$10$^{-2}$ S$.$$cm^{-1}$ /.EX> /.

• 한국결정성장학회지
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• 제17권3호
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• pp.128-132
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• 2007

방전플라즈마 소결법을 적용하여 탄화붕소 세라믹스를 제조하여 그 소결 특성, 미세 구조 및 기계적 특성을 평가하였다. 탄화붕소의 소결에 방전플라즈마 소결법을 적용하여 소결 조제의 첨가 없이 전통적인 소결법보다 낮은 온도에서 99% 이상의 완전 치밀화된 소결체를 제작할 수 있었으며, 탄화붕소 분말의 메탄을 세척을 통하여 분말 표면에 형성되어 있는 $B_2O_3$ 상을 사전에 제거함으로써 결정립의 조대화를 방지하여 균일한 미세구조의 형성을 유도할 수 있었으며 결과적으로 탄화붕소 소결체의 기계적 특성을 향상시킬 수 있었다. 특히 파괴인성의 경우 메탄을 세척을 통하여 30% 이상의 물성 향상을 달성하였다.

• Bulletin of the Korean Chemical Society
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• 제5권2호
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• pp.73-78
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• 1984

Superplastic alloys generally exhibit a three-stage sigmoidal variation of stress (f) with strain rate (s), the stages being named region 1, 2 and 3 according to the increasing order of stress or strain rate. In the recent years, two different types of papers have been published on the plastic deformation of Zn-22% Al eutectoid in region Ⅰ differing in strain-rate sensitivity m (= dln f/dln s). In this paper, the data of the two groups have been analysed by applying Kim and Ree's theory of superplastic deformation. (1) We obtained the parametric values of $X_{gj}/{\alpha}_{gj}\;and\;{\beta)_{gj}$ (g: grain boundary, j = 1,2 indicating flow units) appearing in Kim and Ree's theory [Eq. (2a)]. (2) It was found that the value of $X_{g^2}/{\alpha}_{g^2}$ is small for the group data with small m, i.e., ${\alpha}_{g^2}$, which is proportional to the size of flow unit g2, is large whereas ${\alpha}_{g^2}$ is small for the groups data with large m, i.e., the size of the flow unit g2 is small. In other words, the two types of behavior occur by the size difference in the flow units. (3) From the ${\beta}_{gj}$ value, which is proportional to the relaxation time of flow unit gj, the ${\Delta}H_{gj}^{\neq}$ for the flow process was calculated, and found that ${\Delta}H_{g^2}^{\neq}$ is large for the group data with small m whereas it is small for the group data with large m. (4) The flow-unit growth was studied, but it was concluded that this effect is not so important for differentiating the two groups. (5) The difference in ${\alpha}_{g^2}$ and in the growth rate of flow units is caused by minute impurities, crystal faults, etc., introduced in the sample preparation.

• 마이크로전자및패키징학회지
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• 제28권1호
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• pp.67-71
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• 2021

본 연구에서는 금속 와이어를 촉매로 화학기상증착법을 이용하여 그래핀을 합성하고 구조 및 전기적 특성 변화를 분석하였다. 구리와 니켈의 탄소에 대한 용해도 차이로 인해 구리와이어에서는 단층 그래핀이 성장하였고, 니켈와이어의 표면에는 다층 그래핀이 성장되었다. 또한. 고온의 그래핀 성장 조건에서 구리와 니켈의 재결정화를 통해 결정립의 크기가 증가한 것을 확인하였다. 표면에 그래핀이 합성된 구리와이어의 경우, 최대전류허용치는 1.91×105 A/㎠으로 합성 전 구리와이어에 비해 약 27% 향상되었다. 이와 유사하게, 다층 그래핀이 합성된 니켈와이어의 경우에도 최대전류 허용치는 순수한 니켈와이어 대비 약 36% 향상된 4.41×104 A/㎠으로 측정되었다. 이러한 그래핀/금속 복합소재의 우수한 전기적 특성은 고전류를 요구하는 소자 및 부품에서 안정적인 전기적 흐름을 공급하는데 기여할 수 있을 것이다.