• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2009년도 학술대회 초록집
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• pp.107-109
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• 2009

미세자기학은 분자구조 단위에서 (Micromagnetic modeling) 자성 광물의자화 획득 및 자화 소멸을 연구하는 학문으로 행성지질학적으로 흥미있는 자성 광물의 자화 상태를 수치해석으로 풀어내는 학문이다. 자기이력곡선 분석은 시료를 파괴하거나 가열하지 않고 빠르고 정확하게 자성 광물의 종류 및 크기를 식별할수 있다. 정6면체 형태의 합성자철석이 아닌 자연산에 존재하는 8면체 형태의 모델을 택해야 기존의 실험 결과를 더 잘 설명함을 알아내었다. 특히 8면체의 경우 120 nm 이상의 크기에서 magnetic coercivity와 magnetic remanence가 더욱 안정적이고 커짐을 알아냈다.

• 한국기계가공학회지
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• 제8권4호
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• pp.41-47
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• 2009

This research deals with evaluation of machining accuracy for Parallel Kinematic Machine Tool(PKMT) applied parallel type robot system with high precision and stiffness. For this purpose, machine simulation is carried out to foreknow collision and interference between workpiece and tool. Furthermore, on the basis of machine simulation data, PKMT is manufactured. Machining accuracy such as cylindricity straightness, squareness, parallelism circularity, concentricity pitch error and yaw error, is measured by using coordinate measuring machine. Test piece for evaluation of machining accuracy is designed and manufactured under the standard of ISO 10791-7.

• 한국정밀공학회지
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• 제13권6호
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• pp.114-121
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• 1996

This paper presents an useful technique for assessing the volumetric errors in multi-axis machine tools using the kinematic double ball bar. This system has been developed based on the volumetric error map which describes the 3 dimensional errors of machine tools. The developed system inputs the measured radial data of 3 different planes, respectively XY,YZ,ZX, analysing the volumetric errors such as positional. straightness, angle, and squareness errors, etc. The developed system has been tested in a practical machine tool, and showed high potential for the error assessment of multi-axis machine tools.

• 한국세라믹학회지
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• 제31권3호
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• pp.235-240
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• 1994

The electric and magnetic properties of Mg1.9-2xMn0.05Fe4xO4+${\gamma}$+2wt% Al2O3, and its microstructure have been investigated as a function of ferrite composition (x=0.45, 0.5, 0.55). The microstructure turned out to be independent on the ferrite composition. The resistivity was decreased with increasing Fe contents, whereas the Curie temperature decreased. Saturation magnetization was varied from 1741 to 2022 G with composition, and squareness ratio (SR), coercive force (BHc) were decreased and increased with increasing Fe contents respectively, so the sample which SR and BHc were 0.97 Oe and 1.49 Oe can be attainable at x=0.45.

• Journal of Magnetics
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• 제2권4호
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• pp.130-134
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• 1997

The amorphous Co-based alloy Co66Fe4Ni1B15Si14 (Metglas 2714A) is a suitable magnetic core material for high frequency operation. Appreciable reduction of the coercive force can be achieved by proper heat treatment. In this study, samples annealed at wide temperature range were analyzed using differential scanning calorimetry, high frequency B-H loop tester, X-ray diffractometer and resistivity meter. The results show that coercive force at 10 kHz decreases with in-creasing annealing temperature up to 773 K, but dramatically increases above this temperature. The squareness shows that the magnetic anisotropy on longitudinal direction of the as-cast state remains up to 773 K. Above this temperature, it decreases down to 0.5 that represents random distribution of magnetic domains. The crystallization abruptly occurs between 781 K and 783 K.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1345-1347
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• 1994

High frequency Magnetic Properties of amorphous $Fe_{78}B_{13}Si_9$ ribbon were studied. Squareness ( Br/Bs ) and coercive force ( Hc ) of the specimen field annealed at $380^{\circ}C$ for 2 hrs are changed with the tension and the measuring frequency. So, we could optimise the tension having good magnetic properties at a certain frequency.

• 정보저장시스템학회논문집
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• 제6권2호
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• pp.57-62
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• 2010

This paper measured and analyzed the source of total power loss of an ODD of a notebook computer. It shows that the biggest power loss is the windage loss due to the friction between rotating disk and surrounding air. It measured the power loss by the tilting motion of a rotating disc which is originated from the unbalanced mass of the rotating disc or the squareness between case-rotor and shaft. The power loss of rotating disc due to tilting motion was also calculated by using FLUENT, and it was correlated with the measured one. This paper shows that the one of the effective methods to reduce the power loss of an ODD is to reduce the tilting motion of a rotating disc.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.224-227
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• 1999

Ferroelectric Pb(Zr$\sub$0.52/Ti$\sub$0.48/)O$_3$ thin films were fabricated by pulsed laser deposition, mainly varying process conditions such as substrate temperature, oxygen pressure, and laser energy, PZT films annealed at more than 600$^{\circ}C$ were crystallized into pure perovskite phases regardless of deposition temperatures. Lower deposition temperature of 400$^{\circ}C$ accompanied with post-annealing at 650$^{\circ}C$ resulted in denser microstructures with extremely small grains compated to those of thin films annealed at higher deposition temperatures. Hysteresis curves of thin film with small grains exhibitied good squareness and low leakage characteristics.

• E2M - 전기 전자와 첨단 소재
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• 제10권2호
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• pp.113-118
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• 1997

For the amorphous F $e_{78}$ $B_{13}$S $i_{9-x}$G $e_{x}$ alloy, thermal analysis and measurements of the magnetic properties were carried out. As the content of Ge increased, the crystallization temperature was decreased and the Curie temperature was increased, and the tendencies were almost linear. The core loss of the amorphous alloy for x=1.7, field annealed at optimized condition, was 0.057 W/kg(l.0T, 60Hz), which was about 30% lower than that of no Ge added amorphous alloy (basic composition). Such a low core loss characteristics was thought to be caused by the lower coercive force and good squareness of B-H loop of the alloy.y.y.

• 한국자기학회지
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• 제5권5호
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• pp.618-622
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• 1995

We studied the effects of Pt and Cr addition in a new Co-Cr-P-Pt alloy system with the coercivity higher than 2000 Oe even when they were deposited without substrate heating and bias voltage. The coercivity of the films increased from 1000 to 2000 Oe or higher by addition of 12 at.%Pt. The variation of the anisotropy field with increasing Pt content was similar to that of the coercivity. This indicate that the increase of the coercivity might be associated with increase of the anisotropy field with Pt addition. With the addition of Cr, the coercivity of the films increased up to 8 at.%Cr and the coercive squareness of the films decreased. The angular variation of coercivity deviated at a lower angle from domain wall motion mode as the Cr content increases. From these result, it is believed that the grain isolation of the films is enhanced with the addition of Cr.