• Journal of Electrical Engineering and Technology
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• 제6권3호
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• pp.350-355
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• 2011

This paper deals with the comparison of magnetic characteristics in transverse flux rotary machine according to different stator core composition with the same rotor. Three different stator designs are considered in the analysis according to the material composition of inner and outer stator cores. Electromotive force (EMF), inductance, torque, and core losses are calculated by threedimensional finite element analysis. Calculated and measured results of back-EMF according to the analysis models in dependency on speed are presented.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1167-1168
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• 2006

In this study, the pure iron powder was treated with aqueous phosphoric acid to produce phosphate insulating layer on the surface. After drying the powder, it was compacted in a mold with a diameter of 20mm at 800MPa. The powder compacts were then heat treated at $500^{\circ}C$ for 1 hour. The results showed that insulated iron powder was obtained with uniform phosphate layer by chemical reaction. With increased amount of phosphate layer, the core loss and density of compacts were decreased. It was also found that the addition of ethyl alcohol during insulating reaction resulted in improved core loss value.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2260-2262
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• 2000

In this paper, micromirror which can rotate 45 degree is designed, analyzed and fabricated. The micromirror is parallel to the substrate initially. When external magnetic field is applied, a micromirror can rotate to align its easy axis to the field. The size of micromirror array is $10{\times}10$. The mirror plate and spring is made of aluminium, and nickel is used as soft magnetic material. To obtain 45 degree angular deflection, dimension ratio between stopper length and thickness of sacrificial layer is properly selected. By using electrostatic force, individual actuation is possible.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1046-1048
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• 2004

Inductance is an important parameter determining the characteristics of current waveform in electric motors. There are many kinds of inductances, however, self and mutual inductances are the major components. These inductances are changed under the variation of the magnetic circuit, current, frequency etc., even in the same winding distribution. Therefore this paper deals with the characteristics of inductance according to the shape of stator tooth. The analysis model is newly developed motor made of SMC(Soft Magnetic Composite) to reduce the core loss in high speed. the result of this paper gives the basic understandings of inductance to extend the applications of the motors.

• 한국표면공학회지
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• 제32권3호
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• pp.423-427
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• 1999

Electroplating of 80%Ni permalloy thin plate for magnetic core materials. was studied The convected flow of electrolyte was used for stirring methode. The current density could be increased up to 250mA/$\textrm{cm}^2$ by flow cell. The composition of electroplated layer with vespect to current density and flow rate was investigated and experimental equation to predict the composition was made. How cell yielded more uniform thickness distribution than paddle cell did. The composition distribution was also studied. The thickness was the most important factor to the permeability. The permeability of 5$\mu\textrm{m}$plated permalloy was over 2000 at 1 MHz.

• 한국세라믹학회지
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• 제29권3호
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• pp.195-201
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• 1992

It had been studied the structure and the magnetic properties of singel phase Co2Y(Ba2Co2Fe12O22) powder, one of the hexagonal ferrite. The material was successfully prepared by a commercially applicable coprecipitation method. Adding asqueous solution of BaCl2, CoCl2 and FeCl2(Ba2+:Co2+:Fe2+=1:1:6 in mole ratio) to a mixture of NaOH and hydrogen peroxide solution, coprecipitate was formed with rapid oxidation of ferrous to ferric ion. The coprecipitate transformed to single phase Co2Y powder at heat treatment temperatures as low as 900$^{\circ}C$. The shape of Co2Y particles obtained at 900$^{\circ}C$ was hexagonal plate-like (diameter∼$\mu\textrm{m}$, aspect ratio>10). The structure of the Co2Y was refined by a Rietveld analysis of the measured X-ray diffractogram. The lattice parameters are ao=5.8602${\AA}$ and co=43.512${\AA}$. Co2Y is a soft magnetic material with saturation magnetization 30 emu/g and coecivity 170 . A standard X-ray diffraction pattern for Co2Y is proposed as well.

• 접착 및 계면
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• 제18권2호
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• pp.75-81
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• 2017

본 연구에서는 잘 배열된 나노세공 구조와 자성체 나노입자를 포함하는 메조포러스 카본(Carbonized Ni-FDU-15)을 합성하였다. Carbonized Ni-FDU-15는 구조형성 주형으로 트리블럭 공중합체(F127)를 이용하고, 카본 세공벽 형성 물질로 resol 전구체를 사용하며 질산 니켈(nickel(II) nitrate)을 금속이온 원으로 사용하여 증발유도 자기조립(Evaporation-Induced Self-Assembly, EISA)과 직접 탄화과정을 거쳐서 합성되었다. 메조포러스 카본은 잘 배열된 이차원적 육방체 구조(2D-hexagonal structure)를 가진다. 한편, 세공벽 내 자성체 나노입자는 니켈(Ni) 금속과 니켈 산화물(NiO)이 생성되었다. 나노입자의 크기는 약 37 nm이었다. 그리고 Carbonized Ni-FDU-15의 표면적, 세공크기, 세공부피는 각각 $558m^2g^{-1}$, $22.5{\AA}$ 그리고 $0.5cm^3g^{-1}$이었다. Carbonized Ni-FDU-15는 외부에서 자력을 가하였을 때 자력이 가해지는 방향으로 이동함을 확인하였다. 이러한 자성체 담지 메조포러스 카본 물질은 흡착/분리, 자기 저장 매체, 자성 유체(ferrofluid), 자기 공명 영상(MRI) 및 약물 타겟팅 등의 광범위한 응용 분야에 높은 응용성을 가질 것으로 기대된다.

• 한국지진공학회논문집
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• 제12권4호
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• pp.55-61
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• 2008

면진장치 중에서 최근 많은 연구가 이루어지고 있는 마찰진자 베어링은 적절한 마찰력을 얻기 위해 PTFE(Polytetrafluoroethylene) 마찰재가 이용되고 있다. 본 연구에서는 자력의 반발력을 이용해 재료의 성질을 대체하여 면진성능을 향상 시킬 수 있는 자력을 이용한 마찰진자 베어링을 제안하였다. 제안된 시스템은 자력에 의한 반발력이 수직력을 줄여줌으로써 재료에 의한 마찰계수의 영향을 줄일 수 있음을 가정하였다. 또한 자력의 영향을 가정하기 위해서 간단한 실험을 구성해 보았으며, 자력이 작용을 할 때 마찰계수($\mu$)를 약 20%정도 줄여줄 수 있었다. 실험 결과를 적용한 수치해석을 통해 다양한 지진에 대해서 기존의 마찰진자 베어링보다 향상된 성능을 보여주었고, 특히 지진으로 인해 구조물의 파괴에 작용하는 주된 요소인 최상층의 가속도와 구조물의 상대변위를 비교함으로써 제안된 시스템이 면진장치로서의 기능을 가지고 있음을 확인하였다. 자력을 이용하여 기존의 PTFE 마찰재를 대체할 수 있는 자력을 이용한 마찰진자 베어링의 구조적 설계를 할 수 있다면 마찰진자 베어링의 문제점을 보완한 기초격리장치로서 적용될 수 있을 것으로 사료된다.

• Advances in nano research
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• 제10권1호
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• pp.77-90
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• 2021

In the present study, novel chitosan coated magnetic magnetite (Fe3O4) nanoparticles were successfully biosynthesized from mushroom, Agaricus campestris, extract. The obtained bio-nanocomposite material was used to investigate ultra-fast and highly efficient for removal of Ni2+ ions in a fixed-bed column. Chitosan was treated as polyelectrolyte complex with Fe3O4 nanoparticles and a Fungal Bio-Nanocomposite Material (FBNM) was derived. The FBNM was characterized by using X-Ray Diffractometer (XRD), Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS), Fourier Transform Infrared spectra (FTIR) and Thermogravimetric Analysis (TGA) techniques and under varied experimental conditions. The influence of some important operating conditions including pH, flow rate and initial Ni2+ concentration on the uptake of Ni2+ solution was also optimized using a synthetic water sample. A Central Composite Design (CCD) combined with Response Surface Modeling (RSM) was carried out to maximize Ni2+ removal using FBNM for adsorption process. A regression model was derived using CCD to predict the responses and analysis of variance (ANOVA) and lack of fit test was used to check model adequacy. It was observed that the quadratic model, which was controlled and proposed, was originated from experimental design data. The FBNM maximum adsorption capacity was determined as 59.8 mg g-1. Finally, developed method was applied to soft drinks to determine Ni2+ levels. Reusability of FBNM was tested, and the adsorption and desorption capacities were not affected after eight cycles. The paper suggests that the FBNM is a promising recyclable nanoadsorbent for the removal of Ni2+ from various soft drinks.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.633-636
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• 1999

In this study, we have fabricated amorphous FeZrBAg thin films with low core losses by using DC magnetron sputtering method. After deposition, rotational field annealing (RFA) method was performed in the dc field of 1.5 kOe. The amorphous FeZrBAg thin films produced by annealing at 35$0^{\circ}C$ was founded to have high permeability of 8680 at 100 MHz, 0.2 mOe, low coercivity of 0.86 Oe high magnetization of 1.5 T and very low core loss of 1.3 W/cc at 1 MHz, 0.IT respectively. Excellent soft magnetic properties in a amorphous FeZrBAg thin films in the present study are presumably the homogeneous formation of very fine bcc $\alpha$-Fe crystalline with the 8.2 nm in an amorphous FeZrBAg thin film matrix.