• 한국전기전자재료학회논문지
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• 제18권11호
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• pp.983-989
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• 2005

[ $PZT(Pb(Zr,Ti)O_3)$ ] thin films were deposited by multi-target reactive sputtering method on $RuO_2$ substrates. Pure perovskite phase PZT films could be obtained by introducing Ti-oxide seed layer on the $RuO_2$ substrates prior to PZT film deposition. The PZT films deposited on the $RuO_2$ substrates showed highly voltage-shifted hysteresis loop compared with the films deposited on the Pt substrates. The surface of $RuO_2$ substrate was found to be reduced to metallic Ru in vacuum at elevated temperature, which caused the formation of oxygen vacancies at the initial stage of PZT film deposition and gave rise to the voltage shift in the P-E hysteresis loop of the PZT capacitor. The fatigue characteristics of the PZT capacitors under unipolar wane electric field were different from those under bipolar wane. The fatigue test under unipolar wane showed the increase of polarization. It was thought that the ferroelectric domains which had been pinned by charged defects such as oxygen vacancies and the charged defects were reduced in number by combining with the electrons injected from the electrode under unipolar wave, resulting in the relaxation of the ferroelectric domains and the increase of polarization.

• Journal of Forest and Environmental Science
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• 제32권3호
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• pp.253-261
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• 2016

Xanthoceras sorbifolia seed coat (XSSC) is a processing residue of the bioenergy crop. This work aimed to evaluate the applicability of using the steam explosion to modify the residue for dye biosorption from aqueous solutions by using methylene blue as a model cationic dye. Equilibrium, kinetic and thermodynamic parameters for the biosorption of methylene blue on the steam-exploded XSSC (SE-XSSC) were evaluated. The kinetic data followed the pseudo-second-order model, and the rate-limiting step was the chemical adsorption. Intraparticle diffusion was one of the rate-controlling factors. The equilibrium data agreed well with the Langmuir isotherm, and the biosorption was favorable. The steam-explosion pretreatment strongly affected the biosorption in some respects. It reduced the adsorption rate constant and the initial sorption rate of the pseudo-second-order model. It enhanced the adsorption capacity of methylene blue at higher temperatures while reduced the capacity at lower ones. It changed the biosorption from an exothermic process driven by both the enthalpy and the entropy to an endothermic one driven by entropy only. It increased the surface area and decreased the pH point of zero charge of the biomass. Compared with the native XSSC, SE-XSSC is preferable to MB biosorption from warmer dye effluents.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.77-80
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• 2001

Crystallographic and magnetic characteristics of CoCr-based magnetic thin film for perpendicular magnetic recording media were influenced on preparing conditions. In these, there is that substrate temperature was parameter that increases perpendicular coercivity of CoCrTa magnetic layer using recording layer. While preparation of CoCr-based doublelayer, by optimizing substrate temperature, we expect to increase perpendicular anisotropy of CoCr magnetic layer and prepare ferromagnetic recording layer with a good quality by epitaxial growth. CoCrTa/Si doublelayer showed a good dispersion angle of c-axis orientation $\Delta$$\theta$$_{50}$ caused by inserting amorphous Si underlayer which prepared at underlayer substrate temperature 250C. Perpendicular coercivity was constant, in-plane coercivity was controlled a low value about 2000e. This result implied that Si underlayer could restrain growth of initial layer of CoCrTa thin film, which showed bad magnetic properties effectively without participating magnetization patterns of magnetic layer. In case of CoCrTa/Si that prepared with ultra thin underlayer, crystalline orientation of CoCrTa was improved rather underlayer thickness 1nm, it was expected that amorphous Si layer played a important role in not only underlayer but also seed layer.t also seed layer.r.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.281.1-281.1
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• 2013

Shape control of gold nanocrystal is still one of the most important challenges remaining to achieve geometry dependent properties. Thus far, several strategies have been developed to control the shape of nanoparticles, such as adding capping agents and diverse additives or adjusting the temperature and pH. Here, we used an already established seed-mediated method that allowed us to focus on controlling the growth stage. Cetyltrimethylammonium bromide (CTAB) and ascorbic acid (AA) were used as the ligand and the reducing agent, respectively, without using any additional additives during the growth stage. We investigated how the relative ratio of CTAB and AA concentrations could be a major determinant of nanoparticle shape over a wide concentration range of CTAB and AA. As a result, a morphology diagram was constructed experimentally that covered the growth conditions of rods, cuboctahedra, cubes, and rhombic dodecahedra. The trends in the morphology diagram emphasize the importance of the interplay between CTAB and AA. Furthermore, high-index faceted gold nanocrystal was obtained by two step seeded growth. Already synthesized cubic particles developed into hexoctahedral nanocrystal consisting of 48 identical {321} facets, which indicates that the growth of gold nanocrystal is affected by initial morphology of seed particles. The hexoctahedral gold nanoparticles can be used in catalysis and optical applications which exploiting their unique geometry. Our research can provide useful guidelines for designing various facetted geometries.

• 한국지하수토양환경학회지:지하수토양환경
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• 제24권5호
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• pp.1-10
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• 2019

The effects of liquid phase ozonation on seed dormant alleviation and subsequent seedling growth were studied using two plant seeds of Indian jointvetch (Aeschynomene indica L.) and Indian mallow (Abutilon avicennae Gaertn.). At a constant ozone concentration ($80g/m^3$), contact time varied from 10 to 60 min with 10 min interval. Germination rate, root length, and specific root length were compared after 3-day incubation on gel-medium. The germination rate increased significantly (p<0.05) in the 50 min treatment of Indian mallow by 30% compared to the control. Enhanced root elongation was observed in the seeds of 30 min treatment of Indian jointvetch and 30~50 min treatment of Indian mallow. Specific root length, an indicator of environmental change, did not show significant changes, suggesting the level of ozone treatment has no adverse effect on seedling development. The results indicate that liquid phase seed ozonation can be an effective on-site germination alleviation method in the application of phytoremediation.

• 한국결정학회지
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• 제3권1호
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• pp.23-30
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• 1992

단결정 a-SiC성장시 결정성장로의 감압속도가 결정 성장 속도, 결정성, 성장방향에 미치는 영향 을 고찰해 보기 위해서 승화법으로 (001)면 a-SiC 단결정 종자정위에 단결정 a-SiC를 성장시켰다. 결정성장 초기에는 성장로의 빠른 감압 속도에 따라 결정성장속도가 빨라지고 3C-SiC 다결정이 종자정위에 성장하였고, 감압속도를 느리게 한 경우에는 결정성장 속도가 느려지고 6H-SiC 단결정이 성장하였다. 초기에 단결정층이 성장하는 조건 하에서 2시간 성장후의 단면 성장 양상을 보면, 종자정 하단에서 발생하는 낙은 종자정의 연속적 인 승화 때문에 종자정과 초기의 단결정층이 소멸 되고, 종자정이 놓여있던 혹연 도가니의 바닥으로부터 연속적으로 다결정 층이 성장된 것이 관찰되었다. 그러나, 이러한 종자정의 승화 소멸은 초기 성장 후 냉각과정을 거치고 다시 승온시키는 두 단계 공정을 사용함으로써 효과적으로 억제시킬 수 있었다. 이와같은 방법으로 장시간 성장시킨 결정은 6H-HiC 단결정이었으며, (001) 방향으로 성장하였다.

• Current Photovoltaic Research
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• 제1권2호
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• pp.103-108
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• 2013

Epitaxial growth of a high-quality thin Si film is essential for the application to low-cost thin-film Si solar cells. A polycrystalline Si film was grown on a $SiO_2$ substrate at $450^{\circ}C$ by a Al-assisted crystal growth process. For the purpose, a thin Al layer was deposited on the $SiO_2$ substrate for Al-assisted crystal growth. However, the epitaxial growth of Si film resulted in a rough surface with humps. Then, we introduced a thin amorphous Si seed layer on the Al film to minimize the initial roughness of Si film. With the help of the Si seed layer, the surface of the epitaxial Si film was smooth and the crystallinity of the Si film was much improved. The grain size of the $1.5-{\mu}m$-thick Si film was as large as 1 mm. The Al content in the Si film was 3.7% and the hole concentration was estimated to be $3{\times}10^{17}/cm^3$, which was one order of magnitude higher than desirable value for Si base layer. The results suggest that Al-doped Si layer could be use as a seed layer for additional epitaxial growth of intrinsic or boron-doped Si layer because the Al-doped Si layer has large grains.

• 한국산업정보학회논문지
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• 제18권2호
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• pp.19-25
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• 2013

본 논문에서는 실 도로 환경에서 획득한 영상으로부터 도로 영역을 추적하는 방법을 제안한다. 제안된 방법은 이전 처리 결과로부터 미리 알려진 정보를 이용하여 현재 영상에서 도로를 검출하고 추적하는 방법이다. 제안된 방법은 시스템의 효율을 위해 연속적인 입력 영상에서 하위 60%이내에 도로가 있다고 가정하여 관심의 대상이 되는 영역(Region of Interest, ROI)을 설정하고 이 영역에서만 도로를 검출하고 추적한다. 최초 분할은 플러드필 알고리즘(Flood-fill algorithm)을 수행한 결과로부터 주위 영역과의 유사성을 평가한 후 병합하여 분할한다. 사전 정보로 사용되는 이전 영상에서 분할 결과에서 시드점(Seed Point)을 추출하고 이 시드점을 기준으로 현재 영상을 분할한다. 이전 영상에서 분할된 도로 영역과 현재 영상에서 분할된 결과를 변형된 자카드 계수(Jaccard coefficient)를 이용한 유사도 측정 결과에 따라 다음 영상에서 도로영역을 정제하고 추적한다. 연속적인 입력 영상을 대상으로 실험한 결과는 잡음이 존재하는 영상에서도 도로를 추적하는데 효과적임을 보여준다.

• 한국수산과학회지
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• 제43권3호
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• pp.223-230
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• 2010

To compare seed collection and the growth of Anadara subcrenata in Suncheon and Boseong Bays, environmental factors and the growth of larvae and spats were investigated from August 2008 to July 2009 in commercial farming sites in both bays. The variation in water temperature in both bays was similar, but the salinity was lower in Suncheon Bay than in Boseong Bay. The chlorophyll-a content was higher in Suncheon Bay due to the large inflow of freshwater. The density and shell length of A. subcrenata larvae did not differ significantly between the two bays. However, the relative growth of shell height to shell length was significantly higher in Suncheon Bay (P<0.05). The growth of A. subcrenata spats attached to a collector was significantly faster in Suncheon Bay (P<0.05). The spats in Suncheon and Boseong Bays grew to 24.3 and 21.0 mm in shell length, respectively, within 1 year after spawning, and the shell length reached 35.6 and 34.8 mm, respectively, within 2 years of spawning. The initial spats density was higher in Boseong Bay, but the growth of spats was better in Suncheon Bay. The faster growth of A. subcrenata in Suncheon Bay can be explained by the high chlorophyll-a content in this bay. Based on the low survival (%) and slower growth rate of spats in Boseong Bay, the commercial culture density of A. subcrenata in Boseong Bay should be reduced to the optimum level of the carrying capacity.

• 한국통신학회논문지
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• 제35권6B호
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• pp.970-976
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• 2010

방송과 통신의 융합으로 시작된 미디어 플랫폼간의 융합은 이제 다양한 컨버전스 서비스를 창출하기 위한 S/W 생태계 구축을 시작으로 IT 및 비IT를 망라하여 전 업종으로 융 복합화를 앞당기고 있다. 이러한 컨버전스 환경의 대두와 함께 가정 및 산업용, 그리고 다양한 환경에서의 기기간 자동화 및 연결을 통한 새로운 부가 서비스를 창출하려는 RF4CE (Radio Frequency for Consumer Electronics) 기술이 대두되고 있으며, 본 논문에서는 기기간 효율적인 연결 및 제어를 위해 활용될 수 있는 ZigBee 표준화 기구의 RF4CE 기술에서의 향상된 키 교환 스킴에 대한 방안을 제시하였다. 제시된 방안은 기기간 상호 인증 및 두 단계의 Key Seed 분배 기법 등으로 구성되어 있으며, 본 논문에서는 제안 방안의 분석 및 실제 구현 및 실험을 통해 그 유용성을 검증하였다.