• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.819-823
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• 1995

The oil-based magnetic fluids were sysnthesized using ultra-fine $Fe_{3}O_{4}$ powder dispersed in hydrocarbon oil. To synthesize ultra-fine $Fe_{3}O_{4}$, we carried out the experiments varying the pH of reacting medium and the initial concentration of $Fe^{2+}$. We also investigated the amount of oleic acid to obtain a stable dispersion and the proper base oil of MF for loudspeaker application. The limits of adsorbed amount of oleic acid on the $Fe_{3}O_{4}$ surface were approximately 35~40 percents of the total magnetite weight. As the $Fe_{3}O_{4}$ content increased from 0.1g/cc to 0.6g/cc, the viscosity of oil-based magnetic fluid increased from 1,063cP to 1,828cP, and its saturation magnetization at 10kOe increased from 66G to 242G. When we tested the MF sample to a commercial speaker, improvements were noted.

• Journal of the Korean Electrochemical Society
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• v.8 no.3
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• pp.125-129
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• 2005

We have investigated the electrochemical factors affecting the magnetic properties of hard magnetic CoP nanowires and soft magnetic CoFe nanowires fabricated by ac electrodeposition into self-made AAO(anodic aluminum oxide) nano-templates. AAO template having nano scale pores of high aspect ratio has been prepared through 2-step anodizing of aluminum foil in sulfuric acid. Hard Magnetic properties of CoP nanowires were highly conditional on the applied ac potential which could be a decisive factor to make CoP nanowires made up of either pure hcp crystals or a mixture of hop crystals and fcc crystals. On the contrary to CoFe films, there was no anomalous codeposition in the electrodeposition of soft magnetic CoFe nanowires which exhibited their best saturation magnetization of 238 emu/g at the composition of $Co_{30}Fe_{70}$.

• Journal of the Korean Magnetics Society
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• v.10 no.5
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• pp.220-224
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• 2000

Ultra-fine $Co_{1+x}$F $e_{2-}$2x/ $Ti_{x}$ $O_4$ferrite powders have been prepared by the sol-gel method. The crystallographic and magnetic properties of the sample have been investigated by means of x-ray diffraction, Mossbauer spetroscopy and vibrating sample magnetometry. The formation of nano crystallized particles is confirmed. The x-ray diffractions of all samples with various compositions clearly indicate the presence of spinel structure. The Mossbauer spectra could be fitted as the superposition of two sextets due to F $e^{3+}$ A-site and B-site. The IS and QS values nearly constant with substituted Co-Ti contents, whereas $H_{hf}$ of B-site decreases with increasing Co-Ti substitution in $Co_{1+x}$F $e_{2-}$2x/ $Ti_{x}$ $O_4$. The magnetic behaviour of powders shows that the saturation magnetization and the coercivity decrease with increasing x in $Co_{1+x}$F $e_{2-}$2x/ $Ti_{x}$ $O_4$.$.X>.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.93-96
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• 2015

In this paper, we introduce a fire detection system using context-aware sensor. In existing weather and based on vision sensor of fire detection system case, acquired image through sensor of camera is extracting features about fire range as processing to convert HSI(Hue, Saturation, Intensity) model HSI which is color space can have durability in illumination changes. However, in this case, until a fire occurs wide range of sensing a fire in a single camera sensor, it is difficult to detect the occurrence of a fire. Additionally, the fire detection in complex situations as well as difficult to separate continuous boundary is set for the required area is difficult. In this paper, we propose an algorithm for real-time by using a temperature sensor, humidity, Co2, the flame presence information acquired and comparing the data based on multiple conditions, analyze and determine the weighting according to fire it. In addition, it is possible to differential management to intensive fire detection is required zone dividing the state of fire.

• Journal of Magnetics
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• v.3 no.1
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• pp.31-35
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• 1998

Metal/cobalt ferrite composite thin films with the saturation magnetization (M_s$)of~580 emu/cm3 and the coercivity(Hc) of 1700 Oe were prepared by the reactive sputtering. With increasing substrate temperature, Ms of the thin films increased, while Hc of the thin films decrease. This sttributed to the precipitation of $Co_xFe_{1-x}(x {\appro}x0.62)$ metal phase in the thin films. The metal phase showed the BCC structure ($a_0$=2.89 $\AA$) and Im3m space group. Also, the cobalt ferrite phase was identified as$ CoFe_2O_4$ with a cubic structure ($a_0=8.39 $\AA$$) and a space group of Fd3m. For the higher cobalt content than the stoichiometric composition,$ Co_{37.8}Fe_{62.2}$, the thin films with high Ms and Hc could be obtained in the wide substrate temperature range (200-40$0^{\circ}C$).

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.6
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• pp.82-90
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• 1995

We proposed SAW (Self-Algined Selectively Grown W-Gate) MOSFET structure, and strudied electrical characteristics of the fabricated SAW MOSFETs. The threshold volgate of 0.21${\mu}$m SAW NMOSFET was 0.18 V and that of 0.24 ${\mu}$m SAW PMOSFET was -0.16 V. The subthreshold slope was 74 mV/decade for NMOSFET and 82 mV/decade for PMOSFET. The maximum transconductance of NMOSFET and PMOSFET, at V$_{GS}$=2.5 V and V$_{DS}$=1.5 V, were260 mS/mm and 122 mS/mm. The measured saturation drain current at V$_{GS}$=V$_{DS}$ =2.5 V was 0.574 mA/${\mu}$m for NMOSFET and -0.228 mA/${\mu}$m for PMOSFET. The gate resistance of SAW MOSFET was about m$\Omega$cm and the n+-p junction capacitance of SAW MOSFET was about 10% lowas than that of the conventional MOSFET's.

• Journal of the Korean Magnetics Society
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• v.10 no.4
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• pp.154-158
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• 2000

Crystallographic and magnetic properties of the Co and Ti-doped BaF $e_{12-2x}$ $Co_{x}$ $Ti_{x}$ $O_{19}$(0.0$\leq$x$\leq$1.0) system have been investigated by means of x-ray diffractometry, Mossbauer spectroscopy, and vibrating sample magnetometer. The structure of the system was found to be the magnetoplumbite structure, and the lattice parameter a is nearly constant and c increase as the doped Co-Ti contents increasing. We found that the saturation magnetization nearly unchanged but the coercivity rapidly decreased between x = 0.0 and x = 0.2 with increasing x in BaF $e_{12-2x}$ $Co_{x}$ $Ti_{x}$ $O_{19}$. From the Mossbauer spectra analysis Co-Ti ions prefer 12k, 4 $f_{vi}$ and 2b sites.tes.

• BMB Reports
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• v.35 no.2
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• pp.213-219
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• 2002

Malonyl-CoA decarboxylase (E.C.4.1.1.9) catalyzes the conversion of malonyl-CoA to acetyl-CoA. Although the metabolic role of this enzyme has not been fully defined, it has been reported that its deficiency is associated with mild mental retardation, seizures, hypotonia, cadiomyopathy, developmental delay, vomiting, hypoglycemia, metabolic acidosis, and malonic aciduria. Here, we isolated a cDNA clone for malonyl CoA decarboxylase from a rat brain cDNA library, expressed it in E. coli, and characterized its biochemical properties. The full-length cDNA contained a single open-reading frame that encoded 491 amino acid residues with a calculated molecular weight of 54, 762 Da. Its deduced amino acid sequence revealed a 65.6% identity to that from the goose uropigial gland. The sequence of the first 38 amino acids represents a putative mitochondrial targeting sequence, and the last 3 amino acid sequences (SKL) represent peroxisomal targeting ones. The expression of malonyl CoA decarboxylase was observed over a wide range of tissues as a single transcript of 2.0 kb in size. The recombinant protein that was expressed in E. coli was used to characterize the biochemical properties, which showed a typical Michaelis-Menten substrate saturation pattern. The $K_m$ and $V_{max}$ were calculated to be $68\;{\mu}M$ and $42.6\;{\mu}mol/min/mg$, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.2
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• pp.120-125
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• 2006

By employing a rapid solidification method and atmospheric annealing at $450^{\circ}C-1hr$, we were able to manufacture inexpensively granular CuCo alloy ribbons with thickness of $20{\mu}m$ showing giant magnetoresistance (GMR) ratio of more than 5% at a high magnetic field of 0.5T. To verify maximum MR effect, the MR ratio, saturation magnetization, and microstructure change were investigated with Co contents between 5 and 30 at%. It was possible to obtain GMR ratios of 5.2% at 1.2T, and 3% at 0.5T, which implies an appropriate MR for industrial purpose at a Co content of $8{\sim}l4%$. MR ratio was reduced rapidly at a Co content below 5% due to superparamagnetic effect and at a Co content above 20% due to agglomeration of Co clusters. Surface oxidation during rapid solidification and atmospheric annealing did not have much affect on MR ratio. Our result implies that our economic CuCo granular alloy ribbons may be appropriate for high magnetic field sensor applications with wide content range of $8{\sim}14$ at%Co.

• Journal of the Korean Magnetics Society
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• v.11 no.4
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• pp.168-172
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• 2001

Co-Zn ferrite thin films grown on thermally oxidized silicon wafers were fabricated by a sol-gel method. Magnetic and structural properties of Co-Zn thin films were investigated by using x-ray diffractometer (XRD), atomic force microscopy (AFM), auger electron spectroscopy (AES) and a vibrating sample magnetometer (VSM). Co-Zn ferrite thin films annealed at 400 $^{\circ}C$ presented have only a single phase spinel structure without any preferred crystallite orientation. Their surface roughness of Co-Zn ferrite thin films was shown as less than 3 nm and the grain size was about 40 nm for annealing temperatures over 600 $^{\circ}C$. A moderate saturation magnetization of Co-Zn ferrite thin films for recording media was obtained in this study and there is no significant difference of their magnetic property with those external fields of parallel and perpendicular to planes of the films. The maximum value of the coercivity was obtained as 1,900 Oe for Co-Zn ferrite thin film annealed at 600 $^{\circ}C$.