• 한국자기학회지
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• 제16권6호
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• pp.276-278
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• 2006

스위칭 특성을 향상시키기 위하여 비정질 강자성 CoFeSiB 자유층을 갖는 자기터널접합 (MTJ)의 스위칭 특성을 연구하였다. 자기터널접합의 구조는 $Si/SiO_{2}/Ta$ 45/Ru 9.5/IrMn 10/CoFe 10/CoFe $7/AlO_{x}/CoFeSiB\;(t)/Ru\;60\;(nm)$이다. CoFeSiB는 $560\;emu/cm^{3}$의 낮은 포화자화도와 $2800\;erg/cm^{3}$의 높은 이방성 상수를 가졌다. 이러한 특성이 자기터널접합의 낮은 보자력($H_{c}$)과 높은 자장민감도를 갖게 한다. 이것은 또한 Landau-Lisfschitz-Gilbert 방정식에 근거한 미세자기 전산시뮬레이션을 통하여 submicrometersized elements에서도 확인하였다. CoFeSiB 자유층 두께를 증가함으로서 스위칭 특성은 반자화 자기장의 증가로 인하여 더욱더 나빠졌다.

• Journal of Magnetics
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• 제21권2호
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• pp.164-167
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• 2016

The effect of the B additions on glass formation and magnetic properties is reported for the $Fe_{(87-x-y)}Co_yTi_7Zr_6B_x$ (x = 2, 4, 6 and y = 35, 40) alloy system. The ribbon samples with the width of 2 mm for each composition were prepared by the melt spinning technique; furthermore, their phase information was obtained from X-ray diffraction. Glass formation and magnetic properties were measured using differential scanning calorimetry and vibrating sample magnetometer respectively. The $Fe_{45}Co_{40}Ti_7Zr_6B_2$ (x = 2 and y = 40) system has the nanocrystalline phase identified as ${\alpha}-Fe$, as well as the amorphous phase, whereas all other alloys are fully amorphous. It is associated with the role of B on the glass formation. The widest supercooled liquid region is obtained as 71 K at x = 4 (both y = 35 and 40). The saturation magnetization decreases with the increase of the amount of the B addition, and the highest value is 1.59 T as x = 2 and y = 35 for this alloy system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.87-88
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• 2006

Recently, poly-Si TFT-LCD starts to be mass produced using excimer laser annealing (ELA) poly-Si. The main reason for this is the good quality poly-Si and large area uniformity. We report the influence of channel length and width on poly-Si TFTs performance. Transfer characteristics of p-channel poly-Si thin film transistors fabricated on polycrystalline silicon (poly-Si) thin film transistors (TFTs) with various channel lengths and widths of 2-30 ${\mu}m$ has been investigated. In this paper, we analyzed the data of p-type TFTs. We studied threshold voltage ($V_{TH}$), on/off current ratio ($I_{ON}/I_{OFF}$), saturation current ($I_{DSAT}$), and transconductance ($g_m$) of p-channel poly-Si thin film transistors with various channel lengths and widths.

• 한국진공학회지
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• 제10권1호
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• pp.87-92
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• 2001

자기 Fe-Co(C)나노(nano)캡슐과 Fe-Co 나노입자들이 메탄과 혼합기체($H_2$+Ar) 두 종류의 분위기속에서 각각 아크방전으로 제조되었다. 이 두 종류의 초미세 입자들의 특성과 자기적 성질들을 XRD(X-ray Diffraction), Mossbauer 분광, XPS(X-ray Photoelectron Spectroscopy), TEM(transmission Electron Microscopy), EDS(Energy Disperse Spectroscopy), 화학적 분석, 산소량 측정과 자기 측정 등을 통하여 체계적으로 조사하였다. 메탄기체로부터 분해되어 나온 탄소원소가 미세입자들의 상구조, 자기적 상태 그리고 표면 특성들에 끼치는 효과를 아르곤원소를 사용했을 때와 비교하였다. 두 미세입자에서의 Fe/Co 질량비가 약간 다르게 나타났으며 Fe-Co나노입자의 크기가 Fe-Co(C)나노캡슬보다 약 두배였다. 또한 Fe-Co(C)나노캡슐의 포화자화값이 Fe-Co 나노입자보다 약 8% 높았으며 둘 다 유사한 상구조를 보였다. 핵 표면에 쌓인 껍질들이 매우 얇아 XRD측정으로는 그 존재를 탐지하기 어려웠으나 XPS분석을 통하여 그들이 탄소층과 산소층임을 결론지을 수 있었다.

• 한국분말재료학회지
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• 제10권5호
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• pp.305-309
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• 2003

We report on the formation and chemical leaching of non-equilibrium $Al_{0.6}(Fe_{75}Co_{25})$ alloy produced by rod milling. X-ray diffractometry, transmission electron microscopy, differential scanning calorimetry, scanning electron microscopy, and vibrating sample magnetometry were used to characterize the as-milled and leached specimens. After 400 h, only the $Al_{0.4}Fe_{0.6}$ peak of the body-centered cubic type was present in the XRD pattern. The entire rod milling process could be divided into three different stages of milling: agglomeration, disintegration, and homogenization. The saturation magnetization, $M_s$ decreased with increased milling time, the $M_s$ of the powders before milling was about 113.8 emu/g, the $M_s$ after milling for 400 h was about 11.55 emu/g. Leaching of the Al in KOH of the Al at room temperature from the as-milled powders did not induce any significant change in the diffraction pattern. After the leached specimen had been annealed at $600^{\circ}C$ for 1 hour, the nanoscale crystalline phases were transformed into the bcc Fe, cubic Co, and $CoFe_2O_4$ phases. On cooling the specimen from 85$0^{\circ}C$, the degree of magnetization increased slightly, then increased sharply at approximately 364.8$^{\circ}C$, indicating that the bcc $Al_{0.4}Fe_{0.6}$ phase had been transformed to the Fe and Co phases.

• The Korean Journal of Physiology
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• 제2권2호
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• pp.93-99
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• 1968

The Present study attempted to analyze the fate of CO diffused into the circulating blood through the alveoli. Dogs were induced to CO poisoning by rebreathing CO gas mixture contained in Krog's spirometer, by closed circuit method, for 60 minutes. The spirometer was filled initially with 282 ml of CO and 20 liters of air and oxygen, so the composition of gases were arranged as 1.4% in CO and 50% in $O_2$ at the begining of the rebreathing. Oxygen was added corresponding to the utilization of $O_2$ by the animal in proceeding of the experiment. At 60th minutes of CO rebreathing, the concentration of CO in arterial blood and in mixed venous blood were analysed and compared with each other after the CO contents were corrected with the hematocrit measured in the arterial and mixed venous blood. The distribution of CO gas to other tissues was estimated by the analysis of CO diffused into the cystic bile and into the peritoneal gas pocket which was formed by injection of 300 ml air into the peritoneal cavity prior to the CO gas rebreathing. The blood volume was measured by dilution method using $^{51}Chromium$ tagged red cells. CO amount vanished in the animal body was calculated by subtraction of total CO content in blood stream and the CO remained in closed circuit breathing system from the CO amount given to the breathing system at the begining of the experiment. Results obtained are summarized as follows: 1. The content of CO corrected by the hematocrit value was slightly less in mixed venous blood than in arterial blood. The amount of CO diffused into the cystic bile and into the peritoneal cavity was averaged to 0.1% and 0.4% of the CO amount in 100 ml of blood, respectively. 2. For 60 minutes of CO rebreathing, CO-hemoglobin saturation reached about 77% at the 60th minutes, CO amount vanished in the experimental animal averaged 36.1 ml/dog/hr., or 21% of the total CO volume in the blood stream. The average vanishing rate of CO during 60 minutes of CO rebreathing per kg of body weight was 2.71 ml/hr. Production of CO measured in ten dogs under hypoxic condition averaged 0.023 ml/kg/hr. The major part of the CO vanished in the dogs seemed to be oxidized to $CO_2$ by various tissues of the animal. The conclusion might be delivered as such oxidation of CO to $CO_2$ by animal tissues can play a role in part of the process of recovery and protection of animal from CO-poisoning.

• 한국세라믹학회지
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• 제37권5호
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• pp.425-431
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• 2000

Cobalt ferrite thin films on Corming glass substrate were fabricated by a sol-gel method. Cobalt ferrite thin films with the grain size of 20-35 nm and thickness of 50nm were obtained. Rapid thermal annealing (RTA) and Annealing processes were adopted for comparison of characteristics of the films. Coercivity values were changed with thermal condition and magnetization values were increased as a function of soaking time. With prolonged soaking time, however, it was decreased because of the diffusion of cations from the glass substrate. The RTA process in preparation of cobalt ferrite thin film was the effective way to prevent and to form a single spinel phase in reduced soaking time. The film heated at 600$^{\circ}C$ for 30 minutes by RTA had coercivity of 2,600 Oe, saturation magnetization 460 emu/㎤, and Mr$.$$\delta$ of 1.43 memu/$\textrm{cm}^2$.

• Journal of Magnetics
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• 제2권3호
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• pp.72-75
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• 1997

The temperature dependent saturation magnetization curve of amorphous Fe67 Co18B14Si1, alloy was measured using a SQUID magnetometer and vibrating sample magnetometer from 5 K up to 800 K. Inelastic neutron neutron scattering measurements also have been used to study the long wavelength spin dynamics of this high Tc amorphous ferromagnetic alloy. The magnon dispersion curve exhibit the conventional quadratic relationship E = D (T) q2 + $\Delta$, typical of an iso=obtained from a low temperature magnetization curve, which was consistent with the value obtained from the analysis oif inelastic neutron scattering data after consideration of its temperature dependence.

• Advances in environmental research
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• 제2권1호
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• pp.19-33
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• 2013

Microalgae are receiving an increasing attention because of their potential use as $CO_2$ capture method and/or as feedstock for biofuels production. On the other hand the current microalgae-based technology is still not widespread since it is characterized by technical and economic constraints that hinder its full scale-up. In such contest the growth kinetics of Nannochloris eucaryotum (a relatively unknown marine strain) in batch and semi-batch photobioreactors is quantitatively investigated with the aim of obtaining the corresponding kinetic parameters suitable for process engineering and its optimization. In particular the maximum growth rate was evaluated to be 1.99 $10^{-3}\;h^{-1}$. Half saturation concentrations for nitrates ($K_N$) and phosphates uptake ($K_P$) were evaluated as 5.4 $10^{-4}\;g_N\;L^{-1}$ and 2.5 $10^{-5}\;g_P\;L^{-1}$, respectively. Yield factors for nitrogen ($Y_N$) and phosphorus ($Y_P$) resulted to be 5.9 $10^{-2}\;g_N\;g^{-1}$ biomass and 6.0 $10^{-3}\;g_P\;g^{-1}{_{biomass}}$, respectively. The possibility of using 100% (v/v) $CO_2$ gas as carbon source is also evaluated for the first time in the literature as far as N. eucaryotum is concerned. The strain showed a good adaptability to high concentrations of dissolved $CO_2$ as well as to low pH. The lipid content under 100% $CO_2$ is about 16.16 %wt $wt^{-1}$ and the fatty acid methyl esters composition of the extracted oil is in compliance with the European regulation for quality biodiesel.

• 한국분말재료학회지
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• 제17권2호
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• pp.130-135
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• 2010

Sm-16.7wt%Co alloy powders were prepared by high energy ball milling under the conditions of various milling time and the content of process control agent (PCA), and their microstructure and magnetic properties were investigated to establish optimum processing conditions. The initial powders employed showed irregular shape and had a size ranging from 5 to $110\;{\mu}m$. After milling for 5 h, the shape of powders changed to round shape and their mean powder size was approximately $5\;{\mu}m$, which consisted of the agglomerated nano-sized particles with 15 nm in diameter. The coercivity was reduced with increasing the milling time, whereas the saturation magnetization increased. As the content of PCA increased, the powder size minutely decreased to approximately $7\;{\mu}m$ at the PCA content of 10 wt%. The XRD patterns showed that the main diffraction peaks disappeared apparently after milling, indicating the formation of amorphous structure. The measured values of coercivity were almost unchanged with increasing the content of PCA.