• 대한금속재료학회지
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• 제50권12호
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• pp.867-871
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• 2012

The microstructure and texture of TiN coatings on a Ni-based super-alloy were characterized by the automated version of electron backscatter diffraction (EBSD), EBSD techniques were used to investigate the very fine TiN grain shape and crystal orientation. This study confirmed that EBSD techniques provide a very useful tool for characterization of coating materials. The TiN grains had a special texture, a {001}-fiber texture in the coating layer. It was also found that, in severe environments, the coating performance of equiaxial and randomly oriented TiN is superior to that with columnar structures.

• 암석학회지
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• 제24권2호
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• pp.125-139
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• 2015

거정 장석반정을 다량 함유하는 청산화강암이 연성전단변형을 받아 압쇄암화되는 동안에 일어난 미구조 변화를 파악하기 위해 변형된 청산화강암의 암석구조와 미구조 연구를 수행하였다. K-장석에서 특징적인 미구조는 미세킹크, 미세단열, 밀메카이트, 플레임 퍼어사이트, 코아 외부에 아입자 발달이 없는 코아-맨틀구조 등으로 인지된다. 미세킹크는 미세 단열되거나 미단열된 K-장석들에서 모두 관찰되고, 미세킹크의 축 방향은 미세단열에 의해 경계져 있는 양쪽 K-장석으로 연장된다. 밀메카이트와 플레임 퍼어사이트는 미세 단열된 K-장석들의 입계에 고 변형량의 집중으로 발달한다. 사장석에는 미세단열, 변형쌍정, 킹크대 등이 우세하게 관찰된다. 거정 사장석 반정의 입도 세립화는 역시 미세단열작용에 의해 진행되었다. 그러나 미세 단열된 K-장석과 달리 미세 단열된 사장석에는 코아-맨틀구조가 관찰되지 않는다. 화성기원의 누대구조를 중첩하는 변형쌍정은 변형정도가 낮은 저 변형암에서 종종 관찰된다. 고 변형암에서 변형쌍정의 엽층들은 일반적으로 공액성 킹크대의 둔각 이등분선 방향으로 발달하고, 미세단열 내지 미세단층 되어 무질서한 배열을 보인다. 따라서 이와 같은 특징적인 미구조로부터 청산화강암의 압쇄암화작용 동안에 미구조는 다음과 같이 발달하였음을 제시한다: 거정 K-장석 반정에 미세킹크의 출현과 사장석에 킹크대와 변형쌍정의 출현, 미세단열작용에 의한 거정 장석반정들의 입도 세립화, 미세 단열된 K-장석에 밀메카이트와 플레임 퍼어사이트 그리고 입계이동 재결정작용에 의한 K-장석 조각들의 입도 세립화와 함께 코아-맨틀구조의 출현.

• 한국식품저장유통학회:학술대회논문집
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• 한국식품저장유통학회 2002년도 창립 10주년 기념 국제학술심포지움
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• pp.54-63
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• 2002

Post-harvest technology for rice was focused on in-bin drying system, which consists of about 100, 000 facilities in 1980s. The modernized Rice Processing Complex (RPC) and Drying Storage Center (DSC) became popular for rice dry, storage, process and distribution from 1990s. However, the percentage of artificial drying for rice is 48% (2001) and the ability of bulk storage is about 15%. Therefore it is necessary to build enough drying and bulk storage facilities. The definition of high quality rice is to satisfy both good appearance and good taste. The index for good taste in rice is a below 7% of protein, 17-20% of amylose, 15.5-16.5% of moisture contents and high concentration of Mg and K. To obtain a high quality rice, it is absolutely needed to integrate high technologies including breeding program, cropping methods, harvesting time, drying, storing and processing methodologies. Generally, consumers prefer to rice retaining below b value of 5 in colorimetry, and the whiteness, the hardness and the moisture contents of rice are in order of consumer preference in rice quality. By selection of rice cultivars according to acceptable quality, the periods between harvesting time and drying reduced up to about 20 days. Therefore it is necessary to develop a low temperature grain drying system in order to (1) increase the rate of artificial rice drying up to 85%, (2) keep the drying temperature of below 45C, (3) maintain high quality in rice and (4) save energy consumption. Bulk storage facilities with low temperature storage system (7-15C) for rice using grain cooler should be built to reduce labor for handling and transportation and to keep a quality of rice. In the cooled rice, there is no loss of grain quality due to respiration, insect and microorganism, which results in high quality rice containing 16% of moisture contents all year round. In addition, introducing a low temperature milling system reduced the percentage of broken rice to 2% and increased the percentage of head rice to 3% because of proper hardness of grain. It has been noted that the broken rice and cracking reduced significantly by using low pressure milling and wet milling. Our mission for improving rice market competitiveness goes to (1) produce environment friendly, functional rice cultivars, (2) establish a grade standard of rice quality, (3) breed a new cultivar for consumer oriented and (4) extend the period of storage and shelf life of rice during postharvest.

• 한국농림기상학회지
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• 제20권2호
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• pp.214-227
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• 2018

농업생태계의 복잡한 상호작용을 고려하여 작물생육을 모의하기 위해 객체지향형 작물모델을 개발하였다. 대기, 작물, 토양 및 재배관리를 대표하는 Atmosphere 클래스, Plant 클래스, Soil 클래스, Grower 클래스가 설계되었다. 또한, 이들 클래스들이 구현된 객체들을 하나의 시스템으로 연계하여 통합시스템을 구축하였다. 사례연구로써, 농촌진흥청 본원의 전작시험 포장에서 1985년부터 1986년까지 수행된 실험에서 얻어진 옥수수와 콩의 수량 관측자료와 통합시스템으로 모의된 결과값을 비교하였다. 단작과 간작조건에서 통합시스템으로 예측된 옥수수의 수량은 4% 이내의 낮은 오차율로 모의되었다. 이삭중을 제외한 지상부 건물중의 경우, 옥수수와 콩의 관측값보다 과소추정되는 경향이 있었다. 예를 들어, 옥수수의 경우 잎과 줄기의 생체중 모의값은 관측값에 비해 약 31% 적게 추정되었다. 옥수수가 수확된 시점에서 같이 수확이 된 콩의 경우, 옥수수 보다는 비교적 작은 과소추정 오차를 가졌다. 비록 간단한 형태의 모델들로 구성되었으나, 이러한 모델을 활용하여 복잡한 상호작용을 모의할 수 있는 통합시스템이 개발될 수 있다는 것을 보여주었다. 추후 연구에서, 보다 상세한 작물 생육 모의를 위해 기존의 과정중심의 작물 모델을 역설계하여 통합시스템을 구축하는 연구가 진행되어야 할 것으로 사료되었다.

• 한국자기학회지
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• 제12권2호
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• pp.41-45
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• 2002

졸-겔법으로 제조된 La/sub 0.7/Pb/sub 0.3/MnO₃(LPM)박막의 기판 효과에 따른 저 자장 영역에서의 터널형 자기저항 효과에 대하여 연구하였다. 다결정 LPMO 박막은 SiO₂/Si(100) 기판과 그 위에 확산 방지막(diffusion barrier)으로 안정화 지르코니아(yttria-stabilized zirconia, YSZ) 중간층을 도입한 기판에 증착하였으며, 반면에 c-축 방향 성장을 갖는 박막의 경우 LaA1O₃(001) (LAO) 단결정 기판을 사용하였다. LPMO/LAO 박막에서의 rocking curve 측정 결과 full width half maximum (FWHM) 값은 0.32°값을 가짐을 알 수 있었다. 상온(300 K)에서 측정한 자기저항비(MR ratio) 값은 500 Oe리 외부자장을 인가시 LPMO/SiO₂/Si 박막의 경우 0.52%, LPMO/YSZ/SiO₂/Si 박막인 경우는 0.68% 그리고, LPMO/LAO의 경우에는 0.4%에도 미치지 못하는 값을 가졌다. 이때 MR최대값을 나타내는 peaks는 자기이력 곡선의 보자력 부근에서 나타남으로 그 두 결과가 잘 일치함을 보여 주고 있다. 이러한 저 자장 영역에서의 자기저항 값의 타이는 박막 시료의 기판 효과에 의한 grain boundary특성의 차이로부터 기인된다.

• Progress in Superconductivity
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• 제13권2호
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• pp.127-132
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• 2011

Many research groups have been manufacturing coated conductor by various processes such as PLD, MOD, and MOCVD, but the methods with production cost suitable for wide and massive application of coated conductor did not develop yet. Spray pyrolysis method adopting ultrasonic atomization was tried as one of the possible option. GdBCO precursor films have been deposited on IBAD substrate by spray pyrolysis method at low temperature and converted to GdBCO by post heat treatment. Ultrasonic atomization was used to generate fine droplets from precursor solution of Gd, Ba, and Cu nitrate dissolved in water. Primary GdBCO films were deposited at $500^{\circ}C$ and oxygen partial pressure of 1 torr. After that, the films were converted at various temperatures and low oxygen partial pressures. C-Axis oriented films were obtained IBAD substrates at conversion temperature of around $870^{\circ}C$ and oxygen partial pressures of 500 mtorr ~ 1 torr in a vacuum. Thick c-axis epitaxial film with the thickness of 0.4 ~ 0.5 ${\mu}m$ was obtained on IBAD substrate. C-axis epitaxial GdBCO films were successfully prepared by ex-situ methods using nitrate precursors on IBAD metal substrate. Converted GdBCO films have very dense microstructures with good grain connectivity. EDS composition analysis of the film showed a number of Cu-rich phase in surface. The precursor solution having high copper concent with the composition of Gd : Ba : Cu = 1 : 2 : 4 showed the better grain connectivity and electrical conductivity.

• 한국재료학회지
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• 제20권12호
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• pp.629-635
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• 2010

Abstract In this study characteristics of Al-doped ZnO thin film by HIPIMS (High power impulse sputtering) are discussed. Deposition speed of HIPIMS with conventional balanced magnetic field is measured at about 3 nm/min, which is 30% of that of conventional RF sputtering process with the same working pressure. To generate additional magnetic flux and increase sputtering speed, electromagnetic coil is mounted at the back side of target. Under unbalanced magnetic flux from electromagnet with 1.5A coil current, deposition speed of AZO thin film is increased from 3 nm/min to 4.4 nm/min. This new value originates from the decline of particles near target surface due to the local magnetic flux going toward substrate from electromagnet. AZO film sputtered by HIPIMS process shows very smooth and dense film surface for which surface roughness is measured from 0.4 nm to 1 nm. There are no voids or defects in morphology of AZO films with varying of magnetic field. When coil current is increased from 0A to 1A, transmittance of AZO thin film decreases from 80% to 77%. Specific resistance is measured at about $2.9{\times}10-2\Omega{\cdot}cm$. AZO film shows C-axis oriented structure and its grain size is calculated at about 5.3 nm, which is lower than grain size in conventional sputtering.

• 한국분말재료학회지
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• 제24권2호
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• pp.115-121
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• 2017

In this work, p-type Bi-Sb-Te alloys powders are prepared using gas atomization, a mass production powder preparation method involving rapid solidification. To study the effect of the sintering temperature on the microstructure and thermoelectric properties, gas-atomized powders are consolidated at different temperatures (623, 703, and 743 K) using spark plasma sintering. The crystal structures of the gas-atomized powders and sintered bulks are identified using an X-ray diffraction technique. Texture analysis by electron backscatter diffraction reveals that the grains are randomly oriented in the entire matrix, and no preferred orientation in any unique direction is observed. The hardness values decrease with increasing sintering temperature owing to a decrease in grain size. The conductivity increases gradually with increasing sintering temperature, whereas the Seebeck coefficient decreases owing to increases in the carrier mobility with grain size. The lowest thermal conductivity is obtained for the bulk sintered at a low temperature (603 K), mainly because of its fine-grained microstructure. A peak ZT of 1.06 is achieved for the sample sintered at 703 K owing to its moderate electrical conductivity and sustainable thermal conductivity.

• Journal of Magnetics
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• 제21권1호
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• pp.12-19
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• 2016

The <100> oriented $Fe_{83}Ga_{17}$ alloys with various contents of NbC or B were prepared by directionally solidification method at the growth rate of $720mm{\cdot}h^{-1}$. With a small amount of precipitates, the columnar grains grew with cellular mode during directional solidification process, while like-dendrite mode of grains growth was observed in the alloys with higher contents of 0.5 at% due to the dragging effect of precipitates on the boundaries. The NbC precipitates disperse both inside grains and along the boundaries of $Fe_{83}Ga_{17}$ alloys with NbC addition, and the Fe2B secondary phase particles preferentially distribute along the grain boundaries in B-doped alloys. Precipitates could affect grain growth and improved the <100> orientation during directional solidification process. Small amount of precipitate element addition slightly increased the magnetostrictive strain, and a high value of 335 ppm under pre-stress of 15 MPa was achieved in the alloys with 0.1 at% NbC. Despite the fact that the effect on magnetic induction density of small amount of precipitates could be negligible, the coercivity markedly increased with addition of precipitate element for $Fe_{83}Ga_{17}$ alloy due to the retarded domain motion resulted by precipitates.

• 한국세라믹학회지
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• 제43권11호
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• pp.688-692
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• 2006

Ferroelectric lanthanides-substituted $Bi_4Ti_3O_{12}$ $(Bi_{4-x}Ln_xTi_3O_{12}, BLnT)$ thin films approximately 200 nm in thickness were deposited by metal organic chemical vapor deposition onto Pt(111)/Ti/SiO$_2$/Si(100) substrates. Many researchers reported that the lanthanides substitution for Bi in the pseudo-perovskite layer caused the distortion of TiO$_6$ octahedron in the a-b plane accompanied with a shift of the octahedron along the a-axis. In this study, the effect of lanthanides (Ln=Pr, Eu, Gd, Dy)-substitution and crystallization temperature on their ferroelectric properties of bismuth titanate $(Bi_4Ti_3O_{12}, BIT)$ thin films were investigated. As BLnT thin films were substituted to lanthanide elements (Pr, Eu, Gd, Dy) with a smaller ionic radius, the remnant polarization (2P$_r$) values had a tendency to increase and made an exception of the Eu-substituted case because $Bi_{4-x}Eu_xTi_3O_{12}$ (BET) thin films had the smaller grain sizes than the others. In this study, we confirmed that better ferroelectric properties can be expected for films composed of larger grains in bismuth layered peroskite materials. The crystallinity of the thin films was improved and the average grain size increased as the crystallization temperature,increased from 600 to 720$^{\circ}C$. Moreover, the BLnT thin film capacitor is characterized by well-saturated polarization-electric field (P-E) curves with an increase in annealing temperature. The BLnT thin films exhibited no significant degradation of switching charge for at least up to $1.0\times10^{11}$ switching cycles at a frequency of 1 MHz. From these results, we can suggest that the BLnT thin films are the suitable dielectric materials for ferroelectric random access memory applications.