http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
MAGNETIC PROPERTIES OF FERRITE CORES UNDER DC - BIASED FIELD
H. Fukunaga,S. Masumoto,Y. Ohta,H. Kakehashi,H. Ogasawara 한국자기학회 1995 韓國磁氣學會誌 Vol.5 No.5
Ferrite cores are often magnetized under DC-biased field because they have been intensively used in electronic circuits such as an inverter circuit and a switching regulator circuit. Thus we investigated the effects of DC-biased field on magnetic properties in the frequency range of DC-100㎑ for two kinds of ferrite cores, TDK PC38 and TDK H₃S, which have different shapes of B-H loop from each other. The magnetic loss per cycle, W/f, in the H₃S core decreased with increasing the strength of DC-biased field, although W/f in the PC38 core increased monotonically with DC-biased field. The observed decreasing tendency differs from the previous result for Si-Fe and ferrite cores, and can be attributed to decrease in eddy current loss as well as that in hysteresis loss.
IMPROVEMENT IN HIGH FREQUENCY MAGNETIC PROPERTIES OF THIN AMORPHOUS RIBBONS BY SURFACE OXIDATION
K.Ooae,H.Fukunaga,H.Kakehashi,H.Ogasawara 한국자기학회 1995 韓國磁氣學會誌 Vol.5 No.5
The effects of surface oxidation on magnetic properties were investigated at high frequencies (10k-10㎒) for 7-18㎛ thick Co_(70)Fe_5Si_(15)B_(10) amorphous ribbons with controlled domain structure. Oxidation was accelerated by acid-treatment or anodic oxidation treatment, and the insulation layers were prepared on the surfaces of the ribbons. The acid-treatment was effective in improving permeability and magnetic loss. Although the anodic oxidation treatment was effective in both making oxide layer and thinning, the magnetic properties were not improved compared with the case of the acid-treatment.
Nucleation of CVD Diamond on Various Substrate Materials
Fukunaga, O.,Qiao, Xin,Ma, Yuefei,Shinoda, N.,Yui, K.,Hirai, H.,Tsurumi, T.,Ohashi, N. The Korean Ceramic Society 1996 The Korean journal of ceramics Vol.2 No.4
Diamod nucleation by mw assisted CVD was examined various conditions namely, (1) diamond nucleation on variour substrate materials, such as Si, cubic BN, pyrolytic BN and AIN, (2) AST(Activated species transport) method which promote nucleation of diamond on single crystal and polycrystalline alumina substrate was developed. (3) Effect of bias enhancement of nucleation on single crystalline Si was examined, and finally (4) DST (Double step treatment) method was developed to enhance diamond nucleation on Ni. In this method, we separated carbon diffusing process into Ni, carbon precipitating process from the inside of Ni and diamond precipitation process.
Temperature Dependences of Electric Polarization and Magnetic Ordering of TmMn2O5
Mamoru Fukunaga,H Kimura,K Kohn,Y Noda 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.2I
In order to reveal the relationship between the appearance of ferroelectricity of RMn2O5 and magnetic ordering, we have measured the ferroelectric P-E hysteresis loops and investigated the temperature dependence of the electric polarization of TmMn2O5. Strange P-E loops were ob- served, and a pyroelectric response was observed even on zero .eld cooling. The causes of both strange phenomena are unknown, but the temperature-dependent tendencies of the polarization and of the coercive .eld corresponding to the magnetic phase diagram were observed.
COMPUTER SIMULATION OF MAGNETIC PROPERTIES OF SPRING MAGNETS
N. Kitajima,H. Inoue,Y. Kanai,H. Fukunaga 한국자기학회 1995 韓國磁氣學會誌 Vol.5 No.5
Magnetic properties of model exchange-spring magnets, which are composed of magnetically soft and hard grains, were calculated by means of computer simulation. The dependence of the magnetic properties on the strength of intergrain exchange interaction and the amount of soft grains was studied. The existence of soft grains enhanced the remanence remarkably, and the remanence over 0.8Ms was obtained in the model magnets containing 25% or more soft grains by volume. The calculated coercivity vs. the strength of the exchange interaction curves showed a peak at a critical strength of the exchange interaction, although the remanence increased monotonously with increase in the strength of the exchange interaction. Thus the maximum energy product also reached a peak around the same critical strength. The calculated maximum energy product exceeded 300kJ/㎥ when the magnet is assumed to be composed of Fe₃B and Nd₂Fe₁₄B.
INTERPRETATION OF A SHORT-TERM ANOMALY IN THE GRAVITATIONAL MICROLENSING EVENT MOA-2012-BLG-486
Hwang, K.-H.,Choi, J.-Y.,Bond, I. A.,Sumi, T.,Han, C.,Gaudi, B. S.,Gould, A.,Bozza, V.,Beaulieu, J.-P.,Tsapras, Y.,Abe, F.,Bennett, D. P.,Botzler, C. S.,Chote, P.,Freeman, M.,Fukui, A.,Fukunaga, D.,Ha IOP Publishing 2013 The Astrophysical journal Vol.778 No.1
<P>A planetary microlensing signal is generally characterized by a short-term perturbation to the standard single lensing light curve. A subset of binary-source events can produce perturbations that mimic planetary signals, thereby introducing an ambiguity between the planetary and binary-source interpretations. In this paper, we present the analysis of the microlensing event MOA-2012-BLG-486, for which the light curve exhibits a short-lived perturbation. Routine modeling not considering data taken in different passbands yields a best-fit planetary model that is slightly preferred over the best-fit binary-source model. However, when allowed for a change in the color during the perturbation, we find that the binary-source model yields a significantly better fit and thus the degeneracy is clearly resolved. This event not only signifies the importance of considering various interpretations of short-term anomalies, but also demonstrates the importance of multi-band data for checking the possibility of false-positive planetary signals.</P>
Electrodeposited Fe-Co Films Prepared from a Citric-acid-based Plating Bath
T. Yanai,H. Uto,T. Shimokawa,M. Nakano,H. Fukunaga,K. Suzuki 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
Electrodeposited Fe-Co films are commonly prepared in a boric-acid-based bath. In this research,we applied citric acid instead of boric acid for the plating of Fe-Co films because boron in the wastebath is restricted by environmental-protection regulations in Japan. We evaluated the effect ofcitric acid on the magnetic and structural properties of the films. The saturation magnetization ofthe Fe-Co films slightly increased while the Fe content in the Fe-Co films decreased with increasingcitric acid concentration. The lowest coercivity value of 240 A/m was obtained at a citric acidconcentration of 100 g/L. The plating bath with this citric acid concentration enabled us to obtainFe-Co films with high saturation magnetizations and smooth surface morphologies.
Ito, K .,Orimo, S .,Fujii, H .,Matsushima, T .,Fukunaga, T . 대한금속재료학회(대한금속학회) 2000 METALS AND MATERIALS International Vol.6 No.6
Nanostructured graphite was prepared by mechanical milling under hydrogen and argon atmospheres. The hydrogen concentration in the sample prepared by roiling under hydrogen atmosphere reaches up to 7.4 mass% (CH_(0.95)). Judging from the radial distribution function determined by the neutron diffraction measurement, there are two types of deuterium (hydrogen) coordinations. On the other hand, the hydrogen concentration does not exceed 0.5 mass% by the gas-phase hydrogenation for the sample prepared by milling under argon atmosphere.
Electrodeposited Fe-Ni Films Prepared from a Tartaric-acid-based Bath
T. Shimokawa,T. Yanai,K. Takahashi,M. Nakano,H. Fukunaga,K. Suzuki 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
Recently, we reported a citric-acid-based plating bath is one of the hopeful plating baths forobtaining Fe-Ni films with good soft magnetic properties. In this report, hydroxylic acid of tartaricacid, which belongs to the same acid group at citric acid, was applied to prepare the films, and theeffects of tartaric acid on the magnetic and the structural properties were investigated. Although theoverall trend of the effects obtained for tartaric acid resembles our previous results for the citricacid-based bath, the cathode efficiency for the tartaric-acid-based bath shows a slightly highervalue as compared with that for the citric-acid-based bath. From these results, we conclude thatthe tartaric-acid-based bath is also an environmentally friendly plating bath.