• Journal of Magnetics
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• 제17권4호
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• pp.265-270
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• 2012

We report improved low-field magnetoresistance (LFMR) effects of the $La_{0.7}Sr_{0.3}Mn_{1+d}O_3-Mn_3O_4$ composite films with the nominal composition of $La_{0.7}Sr_{0.3}MnO_3$(LSMO)-50 mol% $Mn_3O_4$. The composite films were fabricated by ex-situ solid phase crystallization (SPC) of amorphous films at the annealing temperature region of $900-1100^{\circ}C$ for 2 h in a pure oxygen atmosphere. The amorphous films were deposited on polycrystalline $BaZrO_3$ (poly-BZO) substrates by dc-magnetron sputtering at room temperature. The Curie temperatures ($T_C$) of all composite films were insignificantly altered in the range of 368-372 K. The highest LFMR value of 1.29 % in 0.5 kOe with the maximum dMR/dH value of $37.4%kOe^{-1}$ at 300 K was obtained from 900 nm-thick composite film annealed at $1100^{\circ}C$. The improved LFMR properties of the composite films are attributed to effective spin-dependent scattering at the $La_{0.7}Sr_{0.3}Mn_{1+d}O_3$ grain boundaries sharpened by adjacent chemically compatible $Mn_3O_4$ grains.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3453-3458
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• 2011

The $Mg_xZn_{1-x}O$ thin films with the various content ratio ranging from 0 to 0.4 were prepared by sol-gel spincoating method. To investigate the effects of content ratio on the structural and optical properties of the $Mg_xZn_{1-x}O$ thin films, scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) were carried out. With increase in the content ratio, the grain size of the $Mg_xZn_{1-x}O$ thin films was increased, however, at the content ratio above 0.2, MgO particles with cubic structure were formed on the surface of the $Mg_xZn_{1-x}O$ thin films, indicating that the Mg content exceeded its solubility limit in the thin films. The residual stress of the $Mg_xZn_{1-x}O$ thin films is increased with increase in the Mg mole fraction. In the PL investigations, the bandgap and the activation energy of the $Mg_xZn_{1-x}O$ thin films was increased with the Mg mole fraction.

• 한국세라믹학회지
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• 제41권4호
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• pp.289-296
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• 2004

양론조성에 근접하는 (Ca/P=1.62-1.67, molar ratio) 휘스커 및 짧은 막대형상의 수산화아파타이트 (Ca$_{10}$(PO$_4$)$_{6}$(OH)$_2$를 $\alpha$-Ca$_3$(PO$_4$)$_2$($\alpha$-TCP) 수용액 (pH 11)의 가수분해와 수열반응으로 각각 합성하였다. 생성된 HAp의 입자형상은 합성방법에, 미세구조의 발달은 반응조건에 주로 의존하였다 가수분해의 경우 반응시간의 경과와 더불어 휘스커 입자들의 상호 교차와 장축방향에서의 응집이 일어났다 반면에, 수열처리에 있어서는 반응과정 중 임계크기(길이 0.75$mu extrm{m}$, 지름 0.3$\mu\textrm{m}$) 이상으로의 입성장은 일어나지 않았으며 과다한 반응시간(20$0^{\circ}C$, $\geq$3시간)은 입자들의 심한 응집을 유발하였다.

• 한국전기전자재료학회논문지
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• 제11권3호
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• pp.229-236
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• 1998

Ferroelectric $Sr_xBi_yTa_2O_{9+\alpha}$/(0.7$\leqSr\leq1.0,\; 2.0\leqBi\leq2.6)$ solutions were prepared by MOD (Metalorganic Deposition) process. These solutions were made into thin films with thickness ranging from 1500~2000${\AA}$ by spin coating. The phase transformation of the SBT thin films by variation of annealing temperature and annealing time were observed using high temperature XRD and SEM. The crystallization and grain growth of SBT thin film were accomplished at $800^{\circ}C$ for 30 minutes after deposition of Pt top electrode by sputtering to prevent electrical breakdown. Ferroelectric properties of the SBT thin films were measured in the range of $\pm$3V\; and\; \pm5V$. The specimen with composition ratio of Sr/Bi/Ta (0.8/2.4/2.0) has the excellent ferroelectric properties ; $2P_r = 10.5,\; 13.2\muC/cm^2 \;at\; \pm3V\; and\; \pm5V$ respectively. Observing the post annealed Pt/SBT/Pt interface by SEM, it was found that Pt electrode sputtered on to the SBT thin film penetrated into the hollow on the SBT thin film, thus decreasing the effective insulation thickness. The effective insulation thickness recovered by post annealing, and this was confirmed by leakage current density measurement.

• 한국세라믹학회지
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• 제40권6호
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• pp.530-538
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• 2003

110 K 상의 산화물 고온초전도체를 B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$C $a_{2.03}$C $u_{3.06}$ $O_{10+}$$\delta$의 출발조성비로 고상반응법에 의해 합성하였다. 합성된 Bi계 110 K 상의 산화물 고온초전도 물질을 다시 분말 상태로 만든 후, MgO 금속산화물 분말을 5~50 wt%의 각 비율로 혼합하였다. MgO 금속산화물 분말이 혼합된 시편들을 820~86$0^{\circ}C$로 24시간동안 최종 소결시켰다. 그 후, 각 시편들에 대하여 x-선, $T_{c}$, SEM 등을 측정하여 MgO 금속산화물 혼합량에 대한 초전도특성 및 표면의 입자 크기 변화 등에 대한 조사를 진행하였다. MgO 금속산화물의 혼합량이 증가됨에 따라 MgO 관련 피크들의 강도 및 2212 상들의 피크들의 비율은 증가되었고, 시편 내 2223 상의 비율은 감소하고 2212상의 비율은 증가되었다.다.은 증가되었다.다.

• 한국해양학회지
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• 제25권1호
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• pp.36-48
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• 1990

본 연구는 동해의 대륙붕 및 대륙사면에서의 다모류 군집의 종 조성과 분포을 알 기 위해 수행되었다. 다모류의 채집은 1985년 4월에 1987년 4월, 10월의 3회의 항해 동안 이루어졌다. 채집된 다모류는 총 36과 112 종이었으며, 우점다모류는 Chaetozone setosa, Aglaophanus malmgrent Ampharete arctica Lerchellules horikoshii, Tharyx sp., 와 Magelona pacifica 등이었다. 본 조사지역의 다모류 군집에 대한 주요 기여종 들은 복반부의 냉수종들이었다. 특히 우점종들은 대륙붕에서부터 대륙사면 상부 혹은 중부에서 주로 분포하며, 특정 서식 깊이를 보였다. 전반적인 평균서식밀도를 300개체 / m$^2$이며, 송풍부도는 15종/0.2 m$^2$ 정도이다. 평균서믹밀도와 종풍부도지수는 600 m 나 그 이상의 수심에서 뚜렷한 변화를 보였다. 우점종의 평균서식밀도와 밀접한 상관 관계를 보인 물리적 환경은 수심, 수온, 니질함량, 평균입도 등이었다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.400-403
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• 2012

$Cu_2ZnSnSe_4$(CZTSe) is emerged as a promising material for thin-film solar cells because of non-toxic, inexpensive and earth abundant more than $Cu(In,Ga)Se_2$ materials. For fabricating compound semiconductor thin-film solar cells, CdS is widely used for a buffer layer which fabricated by a chemical bath deposition method (CBD). Through the experiment, we controlled deposition temperature and mol ratio of solution conditions to find the proper grain 크기 and exact composition. The optimum CdS layers were characterized in terms of surface morphology by using a scanning electron microscope (SEM) and atomic force microscope (AFM). The optimized CdS layer process was applied on CZTSe thin-films. The thickness of buffer layer related with device performance of solar cells which controlled by deposition time. Local surface potential of CdS/CZTSe thin-films was investigated by Kelvin probe force microscopy (KPFM). From these results, we can deduce local electric properties with different thickness of buffer layer on CZTSe thin-films. Therefore, we investigated the effect of CdS buffer layer thickness on the CZTSe thin-films for decreasing device losses. From this study, we can suggest buffer layer thickness which contributes to efficiencies and device performance of CZTSe thin-film solar cells.

• 한국자기학회지
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• 제6권4호
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• pp.211-217
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• 1996

Fe-B-Nb-Cu계 초미세결정합금의 고주파수 대역에서의 연자기 특성을 개선하기 위하여, 이 합금에 대한 Al 첨가효과 및 적정 Al 함유합금을 $10\;\mu\textrm{m}$ 이하의 두께를 가진 극박형으로 만들었을 때의 자기적 특성이 조사되었다. 그 결과 $Fe_{78}Al_{4}Nb_{5}B_{12}Cu_{1}$ 조성합금의 경우에 100 kHz 이상의 고주파 영역에서 높은 실효투자율과 낮은 자심손실 값을 나타내었다. 또 이 합금을 두께 $10\;\mu\textrm{m}$ 이하로 극박화한 경우 1 MHz영역까지의 실효투자율 및 자심손실 특성이 크게 개선되었다. 즉, 두께 $8\;\mu\textrm{m}$의 $Fe_{78}Al_{4}Nb_{5}B_{12}Cu_{1}$ 합금의 1 MHz에서의 실효 투자율은 5,000이었으며, 자심손실은 1 MHz, 0.2 T에서 1.4 kW/kg의 값을 보였다. 이러한 우수한 연자기 특성은 Al 첨가에 의해 자구구조의 변화 및 10 nm 이하의 보다 미세한 $\alpha-Fe$상 생성등에 기인하는 것으로 해석되었다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.272-272
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• 2017

Recently, consumer's demands are increasing for new natural functional and healthful food. These demands have encouraged a better understanding of the biochemical, chemical and nutritional composition of plant products. Superhongmi rice variety was derived from a cross between CG2-3-5-2-6-2 (Heugjinju/Suwon 425) having reddish brown color and Daeribbyeo 1 having a large grain size. Superhongmi rice headed on Sep. 5th and has 94.7 cm culm length. Taxifolin, a phenolic compound in superhongmi rice extract had high ${\alpha}-glucosidase$ inhibitory activity. The ${\alpha}-glucosidase$ inhibitory activity of the superhongmi rice extracts correlated to the taxifolin content and antioxidant activity of the extracts. A new method for quantitative determination of taxifolin in superhongmi rice variety by high performance liquid chromatography was established. A reversed-phase system with Tosoh TSK-gel $C_{18}$ column using 60% methanol in water(pH 2.4) as a mobile phase was developed. Taxifolin was detected at 280 nm and the analysis was successfully carried out within 40 min. In ripening phase, the amount of taxifolin showed a mild decreasing slope. The highest contents was 59.27mg in 100g seed on the 30 days after heading(DAH). The optimum harvesting time, considering taxifolin content, maturity rate and thousand seed weight(TSW) was DAH 50. These results suggest that superhongmi rice which has high taxifolin content has the potential to contribute as a dietary supplement for controlling hyperglycemia and oxidative stress-linked diabetes complications.

• 한국정밀공학회지
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• 제29권3호
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• pp.273-278
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• 2012

$ZrB_2$ has a melting temperature of $3245^{\circ}C$ and a low density of $6.1\;g/cm^3$, which makes this a candidate for application to ultra-high temperature over $2000^{\circ}C$. Beside these properties, $ZrB_2$ has excellent resistance to thermal shock and oxidation compared with other non-oxide engineering ceramics. This paper reviewed briefly 2 research examples, which are related to densification and properties of $ZrB_2$-based ceramics for ultra-high temperature applications. In the first section, the effect of $B_4C$ addition on the densification and properties of $ZrB_2$-based ceramics is shown. $ZrB_2$-20 vol.% SiC system was selected as a basic composition and $B_4C$ or C was added to this system in some extents. With sintered bodies, densification behavior and hightemperature (up to $1400^{\circ}C$) properties such as bending strength and hardness are examined. In the second section, the effect of the SiC size on the microstructures and physical properties is shown. $ZrB_2$-SiC ceramics are fabricated by using various SiC sources in order to investigate the grain-growth inhibition and the mechanical/thermal properties of $ZrB_2$-SiC.