• 한국세라믹학회지
• /
• 제45권4호
• /
• pp.226-231
• /
• 2008

The dense sintered bodies with >95% theoretical densities were successfully obtained from the $BaZrO_3,\;BaCeO_3,\;Ba(Zr_{0.7}Ce_{0.3})O_3$ solid solution, and core-shell structured $0.7BaZrO_3-0.3BaCeO_3$ composite powders prepared by sol-gel methods. The activation energy of $Ba(Zr_{0.7}Ce_{0.3})O_3$ solid solution calculated from the Arrhenius plot of the proton conductivities was similar to that of $BaZrO_3$. The activation energy of core-shell structured $0.7BaZrO_3-0.3BaCeO_3$ composite, however, was much lower than that of $BaZrO_3$ or $Ba(Zr_{0.7}Ce_{0.3})O_3$ solid solution, and was very similar to that $BaCeO_3$. These results could be assigned to the Ce-rich grain boundary which was clearly observed by EDX in core-shell structured $0.7BaZrO_3-0.3BaCeO_3$ composite.

• Nuclear Engineering and Technology
• /
• 제53권12호
• /
• pp.3910-3917
• /
• 2021

Reactor fuel's power distribution plays a vital role in designing the new generation thermionic Space Reactor Power Systems (SRPS). In this paper, the 1/12th SPACE-R's full reactor core was numerically analyzed with two kinds of different axial power distribution, to identify their impacts on thermal-hydraulic and thermoelectric characteristics. In the benchmark study, the maximum error between numerical results and existing data or design values ranged from 0.2 to 2.2%. Four main conclusions were obtained in the numerical analysis: a) The axial power distribution has less impact on coolant temperature. b) Axial power distribution influenced the emitter temperature distribution a lot, when the core power was cosine distributed, the maximum temperature of the emitter was 194 K higher than that of the uniform power distribution. c) Comparing to the cosine axial power distribution, the uniform axial power distribution would make the maximum temperature in each component of the reactor core much lower, reducing the requirements for core fuel material. d) Voltage and current distribution were similar to the axial electrode temperature distribution, and the axial power distribution has little effect on the output power.

• Journal of Plant Biotechnology
• /
• 제33권1호
• /
• pp.11-18
• /
• 2006

고염 스트레스에 대한 연구는 농업 생산성에 직결되기 때문에, 고염에 대한 식물의 반응 및 신호전달, 적응기작은 중요한 연구주제가 되어 왔다. 현재까지 연구된 고염 스트레스에 대한 저항성 기작 및 유전학적 요소들이 많이 밝혀졌는데도 불구하고 아직 많은 연구를 필요로 하고 있다. 그래서 본 연구에서는 모델식물로 잘 알려진 애기장대에 pSK1015 vector로 T-DNA를 삽입하여 고염 스트레스에 대해 감수성을 보이는 돌연변이체, ssm1 돌연변이체를 선별하였다. ssm1 돌연변이체는 고염 스트레스를 받게 되면 이온의 독성 스트레스와 세포내 삼투압의 불균형에서 오는 스트레스에 대해 대조군에 비해 감수성을 보였다. ssm1 돌연변이체의 genomic DNA 상의 T-DNA가 삽입된 부위를 찾기 위하여 genomic DNA mutant library screening을 수행한 결과, 기존의 알려진 syntaxin 기능 및 환경 스트레스에 관련된 F3M18/AtSYP61/OSM1 임을 알 수 있었다.

• 한방비만학회지
• /
• 제7권2호
• /
• pp.77-84
• /
• 2007

Obejectives : Slow-motion strengthening trainings build up muscles better than any other type of training, these exercises focus on balancing and strengthening the muscles in the anatomical center of the body - the core - which includes the back, hip and abdominal muscles. Methods : We had a concept of 'core', and compared core muscles with 12 meridian tendino-musculature based on Thomas Myers' myofascial meridian. Results : It has been suggested that the core muscles correspond to meridians of foot- three Yin and foot- three Yang. The study of core muscles strengthening exercise and movement therapy is requred.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.134-136
• /
• 2003

This paper proposes moving mechanism theory & magnetic core analysis regarding mini magnetic contactor and differential mechanism & bimetal analysis regarding mini thermal overload relay. In shortage of technique, we have experienced many difficulties in magnetic switch development. By this research, we developed core parts about mini magnetic switch and applied the results to optimum mini magnetic switch development

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2008년도 Asian Magnetics Conference
• /
• pp.139.1-139.1
• /
• 2008

• Bulletin of the Korean Chemical Society
• /
• 제31권11호
• /
• pp.3093-3098
• /
• 2010

The core-shell $SnO_2$@AO (A=Ni, Cu, Zn and Mg) films were prepared and the effects of coatings on photovoltaic properties were investigated. Studies on X-ray photoelectron spectroscopy, energy dispersive X-ray analysis and transmission electron microscopy showed the formation of divalent oxides on the surface of $SnO_2$ nanoparticles. It was commonly observed that all the dye-sensitized core-shell films exhibited higher photovoltage than the bare $SnO_2$ film. Transient photovoltage measurements confirmed that the improved photovoltages were related to the decreased time constants for electron recombination.

• Macromolecular Research
• /
• 제16권5호
• /
• pp.434-440
• /
• 2008

Three-armed, star-shaped molecules containing 4-(N,N-diphenyl)amino-4'-nitroazobenzene chromophores were synthesized to study the diffraction behavior after inscribing surface relief gratings. The two molecules differed in terms of their mode of chromophore attachment to the core. In compound 5, they were bound to the core laterally through alkylene spacers, whereas the chromophores were tethered perpendicularly to the core in compound 4. Although 60 wt% of the polar azobenzene chromophores was comprised of large molecules, no aggregation behavior was observed in the absorption spectra of the thin films. The surface relief gratings were elaborated on the surface of the molecular films by the two-beam interference method. The dynamics of grating formation were studied in terms of the diffraction efficiency using two different film samples made up of two star-shaped molecules. The maximum diffraction efficiency of D-$(ENAZ)_3$, compound 4, was measured to be about 30%, which was significantly high. The mode of chromophore attachment affected the dynamic properties of the diffraction gratings.

• Journal of the Optical Society of Korea
• /
• 제18권6호
• /
• pp.650-656
• /
• 2014

We propose a novel active fiber design for selectively generating cylindrical vector beams (CVBs) or cylindrical vector modes (CVMs) which can be applied to conventional fiber lasers. A fiber is designed to have a ring-shaped core refractive index profile which can lead to the best overlap between the active dopant distribution profile and the lowest-order CVM (LCVM) field profile. Therefore, the overlap factor (OVF) of the LCVM becomes even higher than that of the fundamental mode. We emphasize that this condition cannot be satisfied by a conventional step-index core fiber (SICF) but by the ring-doped core fiber (RDCF). Because the lasing threshold is inversely proportional to the OVF, the LCVM can predominantly be stimulated even without going through special procedures to impose extra loss mechanisms to the fundamental mode. We numerically verify that the OVF of the LCVM with the doped ions can significantly exceed that of the fundamental mode if the proposed fiber design is applied. In addition, an RDCF of the proposed fiber design can also operate in a regime containing no higher-order modes besides the LCVM, so that it can selectively and efficiently generate the LCVM without being disrupted by the parasitic lasing of the higher-order modes. We highlight that an optimized RDCF can lead to a >30 % higher OVF ratio than a SICF having the same doped area. The proposed model is expected to be useful for enhancing the efficiency of generating CVBs in an all-fiber format.

• 한국분말재료학회지
• /
• 제25권2호
• /
• pp.132-136
• /
• 2018

Core/shell CdSe/ZnS quantum dots (QDs) are synthesized by a microfluidic reactor-assisted continuous reactor system. Photoluminescence and absorbance of synthesized CdSe/ZnS core/shell QDs are investigated by fluorescence spectrophotometry and online UV-Vis spectrometry. Three reaction conditions, namely; the shell coating reaction temperature, the shell coating reaction time, and the ZnS/CdSe precursor volume ratio, are combined in the synthesis process. The quantum yield of the synthesized CdSe QDs is determined for each condition. CdSe/ZnS QDs with a higher quantum yield are obtained compared to the discontinuous microfluidic reactor synthesis system. The maximum quantum efficiency is 98.3% when the reaction temperature, reaction time, and ZnS/CdSe ratio are $270^{\circ}C$, 10 s, and 0.05, respectively. Obtained results indicate that a continuous synthesis of the Core/shell CdSe/ZnS QDs with a high quantum efficiency could be achieved by isolating the reaction from the external environment.