• 한국분말재료학회지
• /
• 제26권5호
• /
• pp.383-388
• /
• 2019

To improve the mechanical properties of aluminum, graphene has been used as a reinforcing material, yielding graphene-reinforced aluminum matrix composites (GRAMCs). Dispersion of graphene materials is an important factor that affects the properties of GRAMCs, which are mainly manufactured by mechanical mixing methods such as ball milling. However, the use of only mechanical mixing process is limited to achieve homogeneous dispersion of graphene. To overcome this problem, in this study, we have prepared composite materials by coating aluminum particles with graphene by a self-assembly reaction using poly vinylalcohol and ethylene diamine as coupling agents. The scanning electron microscopy and Fourier-transform infrared spectroscopy results confirm the coating of graphene on the Al surface. Bulk density of the sintered composites by spark plasma sintering achieved a relative density of over 99% up to 0.5 wt.% graphene oxide content.

• Journal of Ceramic Processing Research
• /
• 제20권4호
• /
• pp.395-400
• /
• 2019

This study was conducted on the structural and electrical properties of (Ba0.7Sr0.3)TiO3 thin films prepared by the sol-gel and spin-coating methods in order to investigate their applicability to electrocaloric devices. All specimens showed a tetragonal crystal structure and lattice constants of a = 3.972 Å, c = 3.970 Å. The mean grain size of specimens sintered at 800 ℃ was about 30 nm, and the average thickness of 5 times coated specimens was 304~311 nm. In the specimen sintered at 750 ℃, The relative dielectric constant and loss of specimens measured at 20 ℃ were 230 and 0.130, respectively, while dependence of the dielectric constant on unit DC voltage was -8.163 %/V. The remanent polarization and coercive fields were 95.5 μC/㎠ and 161.3 kV/cm at 21 ℃, respectively. And, the highest electrocaloric property of 2.69 ℃ was observed when the electric field of 330 kV/cm was applied.

• 한국정보시스템학회지:정보시스템연구
• /
• 제31권2호
• /
• pp.45-62
• /
• 2022

Purpose Smart farms play a leading role in changing the safety food culture for the citizens. The purpose of this study is to investigate the factors that are important to covid 19-response in the case of ICT smart farm. To do so, we classified the factors as operating effect aspect and industrial wave effect aspect of the smart farm. Design/methodology/approach This study was conducted by visiting Geumsan County, which is attempting to perform a smart farm. Through interviewing farmers representatives based on their operational effect expectations on the smart farm, we derived the industrial crash effect factors and thereafter designed the research model. This study applied AHP, which is an expert decision-making method cans be used to measure relative importance for determining priorities. After interviewing the experts with smart farm, we obtained the factors which are important to smart farm development. Findings According to analysis, the productivity improvement factor was ranked as the most important among the operational effect items. This is consistent with the ultimate goal of smart farms with ICT convergence technology, which is increase the profitability of agriculture. The second place is the factor in the development of infrastructure and infrastructure, and the third and fifth positions were export expansion, environmentally friendly management, and job creation in terms of operational effectiveness.

• Laboraroty Animal Research
• /
• 제34권4호
• /
• pp.223-231
• /
• 2018

Regulation of gastrointestinal hormones have been reported in animal models for constipation undergoing laxative therapy when administered herbal products. We undertook to investigate whether the laxative activity of gallotannin-enriched extracts isolated from Galla Rhois (GEGR) affects the regulation of gastrointestinal hormones, by examining the concentration of four hormones and the activation of their receptors in the loperamide (Lop)-induced constipation model. Stool parameters, including number, weight and water content, were significantly recovered in the Lop+GEGR treated group, relative to the Lop+ vehicle treated group; however, food intake and water consumption were maintained at a constant level. Also, a similar recovery was detected for thickness of mucosa, muscle and flat luminal surface in the Lop+GEGR treated group. Furthermore, concentration of the four gastrointestinal hormones evaluated, namely, cholecystokinin (CCK), gastrin (GAS), somatostatin (SS) and motilin (MTL), were lower in the Lop+vehicle treated group than the No treated group, but were remarkably enhanced in the Lop+GEGR treated group. Moreover, the downstream signaling pathway of MTL and SS receptors were recovered after GEGR administration. Results of the present study therefore indicate that the laxative effects of GEGR treatment may be tightly related with the regulation of gastrointestinal hormones in the Lopinduced constipation model.

• 디지털융복합연구
• /
• 제10권9호
• /
• pp.351-356
• /
• 2012

본 논문은 단일영상의 실안개 정보와 상대적 높이 단서를 기반으로 깊이 지도를 생성하고, 이를 이용하여 2D/3D 변환을 하는 기법에 관한 연구이다. 기존의 실안개 정보만을 깊이 지도로써 이용하는 경우, 안개가 없는 영상에서 오류가 발생할 수 있다. 본 논문에서는 이러한 오류를 줄이기 위해, 상대적 높이 단서 기반의 깊이 지도를 생성하고, 실안개 정보와 결합하는 방법을 제안하였다. 또한 Mean Shift Segmentation을 이용한 gray scale 영상과 실안개 정보의 깊이 지도를 결합하여 객체의 경계를 선명화함으로써 3D 영상의 품질을 향상시킬 수 있도록 하였다. 입력영상과 최종 깊이 지도를 DIBR(Depth Image Based Rendering)을 통해 좌영상과 우영상의 시점영상을 생성하고, 적청영상의 형태로 결합함으로써 3D 영상을 생성하였고, 깊이 지도간의 PSNR을 측정하여 검증하였다.

• 한국환경과학회지
• /
• 제24권12호
• /
• pp.1583-1590
• /
• 2015

The aim of this study was to examine the morphological responses of Hosta longipes, an ornamental plants for heavy metal contaminated soils in urban landscaping, to heavy metals Cd, Pb, and Zn. Plants were grown in artificial soil amended with Cd, Pb, and Zn at concentation of 0, 100, 250, and 500 mg/kg. Plant height, leaf length, leaf width, total leaf number, deaf leaf number, new leaf number, chlorophyll contents, and ornamental value were monitored from May to August. At 4 months after planting, the survival and morphological responses of H. longipes grown in soil amended with Cd at concentrations ${\geq}100mg/kg$ were severely affected compared to those grown in the control soil. Relative leaf length rate and relative leaf width rate were significantly decreased when the concentration of Pb was increased. Total leaf number, chlorophyll contents, and ornamental value were the lowest value in plants grown in soil amended with Pb at level of 500 mg/kg. Relative leaf length rate and relative leaf width rate, total leaf number, dead leaf number, new leaf number, and ornamental values had a tendency of decrease when plants were grown in soils amended with Zn. However, no significant difference was found among treatments except for plants were grown in soils amended with 500 mg/kg Zn. Therefore, Hosta longipes might be useful for phytoremediation of Zn contaminated sites as herbaceous ornamental plants.

• 한국세라믹학회지
• /
• 제45권7호
• /
• pp.411-417
• /
• 2008

Aerosol Deposition Method (ADM) is a novel technique to grow ceramic thick films with high density and nano-crystal structure at room temperature. $^{1,2)}$ For these unique advantages of ADM, it would be applied to the fabrication process of 3-D integration ceramic modules effectively. However, it is critical to control the properties of starting powders, because a film formation through ADM is achieved by impaction and consolidation of starting powders on the substrates. We fabricated alumina thick films by ADM for the application to integral substrates for RF modules. When the as-received alumina powders were used as a starting material without any treatments, it was observed that the dielectric properties of as-deposited alumina films, such as relative permittivity and loss tangent, showed high dependency on the frequency. In this study, some techniques of powder pre-treatments to improve the dielectric properties of alumina thick films will be shown and the effects of starting powders on the properties of AD films will be discussed.

• 디지털융복합연구
• /
• 제15권5호
• /
• pp.225-233
• /
• 2017

인공지능 관련 기술이 미래 핵심 기술로 떠오르면서 많은 투자가 이뤄지고 있지만, 우리나라는 부족한 투자규모로 기술 발전에 한계가 존재한다. 따라서 선진국을 빠르게 추격하기 위한 중장기 기술개발 로드맵 수립이 필요하다. 이에 본 논문에서는 'Web of Science'에서 한국인 저자가 게재한 SCI(E)저널의 논문 중 인공지능 관련 논문을 수집하여 빈도분석과 키워드 네트워크 분석을 진행하였다. 분석 결과 인공지능 분야 논문은 매년 약 10%의 평균적인 성장세를 보였지만 상대적인 비율은 감소하였다. 매년 'Neural Network'관련 연구가 많은 수를 나타냈지만, 시간의 흐름에 따라 인공지능 관련 연구는 이론적 연구에서 실용 응용적 연구가 많아지는 것을 확인할 수 있었다. 우리나라의 연구 분야는 국소적이며 기술적인 부분에 대한 연구 위주로 진행되었다. 따라서 우리나라는 인공지능에 대해 이론 기술적 반복수행에서 벗어나 총체적이고 포괄적인 미래 방향을 제시하기 위한 연구가 진행되어야 할 것이다.

• 디지털융복합연구
• /
• 제10권11호
• /
• pp.403-418
• /
• 2012

본 논문에서는 IT와 서비스 산업의 디지털융합 모델의 가치 창출요소의 시너지 효과를 이론적으로 정형화하고 실증분석을 통하여 시사점을 도출하였다. 경영전략 분야의 상황적합 이론에 기반 하여 IT융합의 근원적 가치요소를 고정형, 이동형으로 구분하고 이들 가치의 전략적 적합과 서비스 프로세스 제약완화 기여 등을 시너지 효과에 초점을 맞추어 탐색하였다. 본 논문에서 도출된 융합 시너지 연구 모델은 실증분석을 통하여 계층적 회귀분석 방법을 통하여 검증하였으며, 분석 결과 융합 모델의 가치 창출 요소의 유용성은 산업 별로 확연하게 구분되며 혁신에 의한 상대적 이점과 함께 일상생활 습관과의 부합성이 채택의 중요한 영향을 미치는 것이 발견되었다. IPTV 등에 기반 한 고정형 가치와 스마트 폰 등 모바일 기반 응용에 대한 시너지 효과와 프로세스 제약완화 등에 대한 시너지 효과가 제한적으로 나타났으며 이는 이들 가치가 서로 독립적으로 존재하며 융합 산업의 고유 특성과의 조화가 핵심적이라는 시사점이 도출되었다. 본 연구 결과는 향후 IT기반 산업 융합 모델 비즈니스 모델 연구에 유용한 시사점을 제공한다.

• 한국환경복원기술학회지
• /
• 제24권5호
• /
• pp.15-23
• /
• 2021

This study was carried out to suggest an appropriate plant combination by evaluating the growth of flowering ground-cover plants planted with Festuca glauca 'Eljiah Blue' on the roof-top environment. As for the plant materials, Allium senescens and Chrysanthemum coreanum which are shorter than Festuca glauca 'Eljiah Blue' and Sedum takesimense and Agastache rugosa which are taller than Festuca glauca 'Eljiah Blue' were selected. Festuca glauca 'Eljiah Blue' was planted on Conrol, and Festuca glauca 'Eljiah Blue' with Allium senescens (T1), Festuca glauca 'Eljiah Blue' with Sedum takesimense (T2), Festuca glauca 'Eljiah Blue' with Agastache rugosa(T3), and Festuca glauca 'Eljiah Blue' with Chrysanthemum coreanum (T4) were planted in each experimental plot. Plant height and covering rate were measured to evaluate the growth of Festuca glauca 'Eljiah Blue'. Also, relative growth rate (RGR) of plant height, RGR of plant width, and mortality rate of the flowering ground-cover plants were estimated. Plant height and cover rate of Festuca glauca 'Eljiah Blue' was greatest in T3. RGR of plant height was greater in the order of Agastache rugosa, Allium senescens, Chrysanthemum coreanum, and Sedum takesimense. In particular, RGR of plant width was also greatest for Agastache rugosa. Mortality rates of Agastache rugosa and Allium senescens were lowest at 11%. Therefore, based on good growth of Festuca glauca 'Eljiah Blue' planted with Agastache rugosa, these results were suggested as a desirable combination of plant species for rooftop gardening.