• 천문학논총
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• 제30권2호
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• pp.65-67
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• 2015

The surfaces of most atmosphereless solar system objects are referred to as regolith, layers of loosely connected fragmentary debris, produced by meteorite impacts. Measurements of light scattered from such surfaces provides information about the composition and structure of the surface. A suitable way to characterize the scattering properties is to consider how the intensity and polarization of scattered light depends on the particle size, composition, porosity, roughness, wavelength of incident light and the geometry of observation. In the present work, the effect of porosity on bidirectional reflectance as a function of phase angle is studied for alumina powder with grain size of $0.3{\mu}m$ and olivine powder with grain size of $49{\mu}m$ at 543.5 nm. The optical constants of the alumina sample for each porosity were calculated with Maxwell Garnett effective medium theory. On using each of the optical constants of alumina sample in Mie theory with the Hapke model the variation of bidirectional reflectance is obtained as a function of phase angle with porosity as a parameter. Experimental reflectance data are in good agreement the model. For the olivine sample the effect of porosity is studied using Hapke (2008).

• 한국자기학회지
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• 제22권2호
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• pp.42-44
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• 2012

니켈-철 합금 박막의 성분을 연속적으로 변화시키는 방법을 조사하였다. 일정한 전해액에 가해지는 도금 전류와 전압의 변화에 따라 박막 내 니켈과 철의 상대적 함유량의 조절이 가능했는데, 그 결과 도금 박막의 보자력, 각형비 및 포화자기장이 변화하였다. 정전류도금과 정전압 도금 방법으로 박막 내 철의 함유량을 증가시킴에 따라 박막의 입도는 증가하였고 보자력은 감소하는 경향을 나타내었다.

• Transactions on Electrical and Electronic Materials
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• 제3권3호
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• pp.25-28
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• 2002

In this study, microstructural, dielectric and electrical properties of (Pb$\sub$0.83/) (La$\sub$0.2/Ce$\sub$0.8/)$\sub$0.08/TiO$_3$(PCT) ceramics as a function of MnO$_2$ addition and electrode size variation were investigated for 30 MHz high frequency ceramic resonator application. Grain size was gradually increased according to the increase of MnO$_2$ addition amount. Moreover, the density showed a constant value with increasing MnO$_2$ addition amount. Dielectric constant was decreased with increasing MnO$_2$ addition amount. Curie temperature of all the composition ceramics was nearly constant around 330$^{\circ}C$. The maximum D.R.of 50.5 dB and maximum Q$\sub$mt3/ of 1842 in the 3$\^$rd/ overtone vibration mode were appeared at the composition of 0.3wt% MnO$_2$, respectively.

• Corrosion Science and Technology
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• 제3권3호
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• pp.112-117
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• 2004

This work investigated the material properties of Ni-P-B alloy electrodeposits obtained from a Ni sulfamate bath as a function of the contents of the P and B sources($H_3PO_3$ and dimethyl amine borane complex(DMAB), respectively) with/without additives. Chemical composition, residual stress, microstructure and micro hardness were investigated using ICP(inductively coupled plasma) mass spectrometer, flexible strip, XRD, TEM and micro Vickers hardness tester, respectively. From the results of the compositional analysis, it was observed that P and B are incorporated competitively during the electrodeposition and the sulfur from the additive is codeposited into the electrodeposit. The measured residual stress value increased in the order of Ni, Ni-P, Ni-B and Ni-P-B electrodeposits indicating that boron affects the residual tensile stress greater than phosphorus. As the contents of the alloying element sources of P and B increased, crystallinity and the grain size of the electrodeposit decreased. The effect of boron on crystallinity and grain size was also relatively larger than the phosphorus. It can be explained that the boron with a smaller atomic radius contributes to the increase of residual stress in the tensile direction and the larger restraining force against the grain growth more significantly than the phosphorus with a larger atomic radius. Introduction of an additive into the bath retarded crystallization and grain growth, which may be attributed to the change of the grain growth kinetics induced by the additive adsorbed on the substrate and electrodeposit surfaces during electrodeposition.

• 한국세라믹학회지
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• 제26권3호
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• pp.423-437
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• 1989

Al2O3/ZrO2 composites were prepared by precipitation method using Al2(SO4)3.18H2O, ZrOCl2.8H2O and YCl3.6H2O as starting materials and NH4OH as a precipitation agent. Al2O3/ZrO2 composites(series A) were prepared by mixing Al2O3 powder obtained by single precipitation method with ZrO2(＋3m/o Y2O3) powder obtained by co-predipitation method. Al2O3/ZrO2 composites (series B) were prepared by co-precipitation method using the three starting materials. In all cases, the composition was controlled as Al2O3-15v/o ZrO2(＋3m/o Y2O3). The composites of series A showed higher final relative densities than those of series B and tetagonal ZrO2 in all cases was retained to about 95% at room temperature. ZrO2 particles were coalesced more rapidly in grain boundary of Al2O3 than within Al2O3 grain. ZrO2 particles were located at 3-and 4-grain junction of Al2O3 and limited the grain growth of Al2O3. It was observed that MgO contributed to densification of Al2O3 but limited grain growth of Al2O3 by MgO was not remarkable. In all Al2O3/ZrO2 composites, exaggerated grain growth of Al2O3 was not observed and Al2O3/ZrO2 composites were found to have homogeneous microstructures.

• 생태와환경
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• 제33권1호통권89호
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• pp.31-37
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• 2000

본 연구는 광양만 퇴적물의 이화학적 조성과 중금속 함량을 알아보기 위해 함수율, COD, $H_{2}S$, 입도 및 10가지의 중금속을 17개 조사지점에 대해 분석${\cdot}$조사하였다. 조사기간동안 나타난 결과로서 퇴적물의 함수율 변화는 35.5${\sim}$53.8%를 나타내었다. COD와 $H_{2}S$는 각각 3.8${\sim}$12.9 mg/g, 0.1${\sim}$11.4 ${\mu}g/g$를 나타내었다. 퇴적물 입도의 구성은 입경 $74{\mu}m$ 이하가 40.5${\sim}$86.7% 74${\mu}m$ 이상이 11.5${\sim}$43.0%로 나타났다. 등농도 분포도를 이용한 중금속의 공간분포로부터 광양만 퇴적물에 영향을 미치는 몇 곳의 배출원을 추정할 수 있었다. 중금속 배출원 중 여천공단 내의 신풍천, 쌍봉천 그리고 하수처리장의 방류수역이 주요 배출원으로 판정되었다. 중금속의 분석 결과를 US, EPA 비오염해역의 guideline에 비교할 때 납과 수은은 guideline에 모두 적합한 것으로 평가되었으나 망간, 아연, 구리, 철, 비소, 크롬 등은 guideline을 모두 상회하고 있었다.

• Fisheries and Aquatic Sciences
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• 제17권2호
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• pp.249-253
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• 2014

An 8-week feeding experiment was conducted to determine the influence of dietary distillers dried grain (DDG) on the growth and body composition of juvenile abalone Haliotis discus hannai. Five diets were formulated to contain 0% (DDG0), 15% (DDG15), 30% (DDG30), 45% (DDG45), and 60% (DDG60) DDG, and three replicate groups of abalone (average body weight: $3.6{\pm}0.21$ g) were fed one of the experimental diets at a feeding rate of 5% body weight per day once daily (17:00 h) for 8 weeks. Survival, shell length, and shell width of juvenile abalone were not affected by dietary DDG levels (P > 0.05). Weight gains of juvenile abalone fed DDG15 and DDG30 diets were not different compared to DDG0, but abalone fed DDG45 and DDG60 diets gained less weight than those fed DDG0 (P < 0.05). Soft body weight/body weight ratio of juvenile abalone fed the DDG60 diet was lower than that of those fed the DDG0 diet (P < 0.05), but proximate composition of the soft body was not affected by dietary DDG levels (P > 0.05). The results of this experiment suggest that DDG is a good replacement for wheat flour and soybean meal, and can be used up to 30% in the diet to maintain the growth performance of the juvenile abalone.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.280-290
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• 1999

The microstructures of a Tl$_{0.8}Pb_{0.2}Bi_{0.2}Sr_{1.6}Ca_2Cu_3O_{9+{\delta}}$/Ag tape (tape I ) with J$_c$ of 17,600 A/cm$^2$ at 77 K and 0 T and three Tl$_{0.8}Pb_{0.2}Bi_{0.2}Sr_{1.8}Ba_{0.2}Ca_{2.2}Cu_3O_{9+{\delta}}$/Ag tapes with J$_c$'s of 9,300 (tape II), 16,700 (tape III) and 25,200 A/cm$^2$ (tape IV)prepared using the powder-in-tube method and an in-situ reaction method, were investigated using scanning electron microscopy and high-resolution transmission electron microscopy, and compared each other. ln the tape preparation, an intermediate rolling process was incorporated during final heat-treatment for the last tape, but not for the rest of the tapes. The microstructural analysis revealed clear differences in grain-texturing, crystallographic defects and impurity phases, depending on the chemical composition of the tape. Tendency of directional grain-alignment increased in an order of tapes I, II III and IV. In tape IV, T1-1223 grains are textured, at least in local regions. In crystallographic defects, while stacking faults were prevalent in the former composition, dislocations and voids were frequently observed in the latter. Also impurity phases were appeared to be more abundant in the former than in the latter. The relationship between 1,and the microstructure in the tapes was attempted to explain in a term of grain-linking.

• 한국자기학회지
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• 제12권2호
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• pp.57-63
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• 2002

Nd-Fe-B계 소결자석의 특성을 향상시키기 위해서는 Nd-Fe-B계 합금의 조성 및 제조공정을 조절하여 자성분말의 입도 및 입도분포, 강자성상인 N $d_2$F $e_{14}$B상의 분율, 자성분말의 배향도, 산소 함량, grain size 등과 같은 factor들을 최적화 하여야 한다. 본 연구에서는 실험실 규모로 Nd-Fe-B계 합금 조성 및 공정 조절을 통하여 Nd-Fe-B계 소결자석을 제조하는 연구를 수행하였으며, 분쇄매체 분쇄시간 및 ball size에 따른 Nd-Fe-B계 소결자석의 자기적특성을 분석하여 최적의 분쇄조건을 조사하였다. 또한 분쇄공정 중 FeGa합금을 첨가하여 잔류자속밀도의 감소없이 Nd-Fe-B계 소결자석의 보자력을 향상시킬 수 있었다. 이와 같은 분쇄 조건의 연구, FeGa 합금에 의한 보자력 향상, 건식분쇄 방법 및 powder blending 공정을 적용하여 잔류자속밀도( $B_{r}$,) : 14.4kG, 보자력($_{i}$ $H_{c}$) : 9.4kOe, 최대자기에너지적((BH)$_{\max}$) : 47 MGOe의 자기적 특성을 갖는 Nd-Fe-B계 소결자석을 제조하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제27권12호
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• pp.1736-1743
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• 2014

This study was designed to test the effects of dietary distillers dried grain (DDG) level on the growth performance, feed utilization, body composition and antioxidant activity of juvenile red seabream (Pagrus major). Six isonitrogenous and isocaloric diets were formulated to contain 0%, 5%, 10%, 15%, 20%, and 25% DDG from rice (designated as DDG0, DDG5, DDG10, DDG15, DDG20, and DDG25), respectively. Juvenile red seabream averaging $10.1{\pm}0.05g$ were randomly distributed into 400-L tanks in a flow through systems. Three replicate groups of fish were fed one of the experimental diets to visual satiation two times a day for 10 weeks. Survival, weight gain, feed efficiency, protein efficiency ratio and hepatosomatic index of fish were not affected by dietary DDG levels (p>0.05). Proximate and amino acid composition of whole body in juvenile red seabream were not affected by dietary DDG levels (p>0.05). Plasma content of total protein, glucose, cholesterol, glutamic-pyruvic transaminase, phospholipid and triglyceride were not affected by dietary DDG levels (p>0.05). 1, 1-Diphenyl-2-picryl-hydrazyl radical and alkyl radical scavenging activities in plasma and liver of fish were not affected by dietary DDG levels (p>0.05). The results of this experiment suggest that DDG has the potential to replace plant origin ingredients such as wheat flour and corn gluten meal and could be used up to 25% in diet without incurring negative effects on the growth performance of juvenile red seabream.