• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.173-173
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• 2000

Multilayered films (MLF) consisting of transition metals and semiconductors have drawn a great deal of interest because of their unique properties and potential technological applications. Fe/Si MLF are a particular topic of research due to their interesting antiferromagnetic coupling behavior. although a number of experimental works have been done to understand the mechanism of the interlayer coupling in this system, the results are controversial and it is not yet well understood how the formation of an iron silicide in the spacer layers affects the coupling. The interpretation of the coupling data had been hampered by the lack of knowledge about the intermixed iron silicide layer which has been variously hypothesized to be a metallic compound in the B2 structure or a semiconductor in the more complex B20 structure. It is well known that both magneto-optical (MO0 and optical properties of a metal depend strongly on their electronic structure that is also correlated with the atomic and chemical ordering. In order to understand the structure and physical properties of the interfacial regions, Fe/Si multilayers with very thin sublayers were investigated by the MO and optical spectroscopies. The Fe/si MLF were prepared by rf-sputtering onto glass substrates at room temperature with a totall thickness of about 100nm. The thicknesses of Fe and Si sublayers were varied from 0.3 to 0.8 nm. In order to understand the fully intermixed state, the MLF were also annealed at various temperatures. The structure and magnetic properties of Fe/Si MLF were investigated by x-ray diffraction and vibrating sample magnertometer, respectively. The MO and optical properties were measured at toom temperature in the 1.0-4.7 eV energy range. The results were analyzed in connection with the MO and optical properties of bulk and thin-film silicides with various structures and stoichiometries.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.221-226
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• 2000

We observed the spatial distributions of atom in a magneto-optical trap. These distributions include sphere, stick, ring, ring with core, sphere-sphere, sphere-ring etc. Coordinate-dependent asymmetry radiation force (CDARF) that arises due to laser beams misalignment and transverse profile of the laser beams is exerted on atoms, and the shape of trapped cloud is changed with the misalignment parameter. We use equations of motion that takes into account the Zeeman sublevels of the 87Rb atom, magnitude and direction of magnetic field, polarization of trapping lasers, and transverse profile of the laser beams. A theoretical analysis of the equation of motion for the trapped atom explained all the experimental observations.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.118-120
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• 2000

Currently, x-ray is mostly used for the diagnosis of dental cavity and osteoporosis. The osteoporosis is broadly defined as a decrease in the amount of bone mass per unit volume of the bone. Clinically the manifestation of low bone mass presents a clinical problem to the general population as an increase in fracture risk and especially in aging population[1]. Although the amount of the irradiated x-ray to the human body for the clinical diagnosis is relatively small, the exposition of the x-ray to the human body should be minimized as much as possible, since the x-ray is an ionizing radiation. To investigate other possible systems replacing X-ray, ultrasonic imaging and MRI(Magneto-Resonance-Imaging) systems were studied. Unfortunately, an effective and safe diagnosis tool for detecting the dental cavity and the osteoporosis is currently lacking. (omitted)

• Journal of the Korean Magnetics Society
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• v.18 no.1
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• pp.14-18
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• 2008

Bismuth-substituted yttrium iron garnet(Bi:YIG) films, which show excellent magnetic and magneto-optical properties as well as low optical losses by optimizing their deposition and post-annealing condition, have been attracting great attention in optical device research area. In this study, the Bi:YIG thick films were deposited with the aerosol deposition method for the final purpose of applying them to optical isolators. Since the aerosol deposition is based on the impact adhesion of sub-micrometer particles accelerated by a carrier gas to a substrate, the flow rate of carrier gas, which is in proportion to mechanically collision energy, should be treated as an important parameter. The Bi:YIG($Bi_{0.5}Y_{2.5}Fe_5O_{12}$) particles with $100{\sim}500$ nm in average diameter were carried and accelerated by nitrogen gas with the flow rate of 0.5 l/min${\sim}$10 l/min. The coercive force decreased from 51 Oe to 37 Oe exponentially with increasing gas flow rate. This is presumably due to the fact that the optimal collision energy results in reduction of impurity and pore, which makes the film to be soft magnetically. The saturation magnetization decreased due to crystallographical distortion of the film with increasing gas flow rate.

• Journal of the Korean Magnetics Society
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• v.6 no.3
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• pp.174-178
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• 1996

A method was studied which simulate signal and noise for magneto-optical disk drive system Recorded mark patterns and incident laser beam were modeled and discretized. Using them readout waveformj and amplitude were simulated. Adding Gaussian random noise to the readout signal and executing one dimensional discrete FFT (Fast Fourier Transform) algorithm signal and noise spectrum was estimated. From the spectrum, CNR (Carrier to Noise Ratio) was obtained.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.273.2-273.2
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• 2007

• Proceedings of the Korean Vacuum Society Conference
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• 2001.07a
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• pp.93-93
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• 2001

• Korean Journal of Materials Research
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• v.5 no.4
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• pp.476-482
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• 1995

TbFeCo 박막의 Facing Targets Sputtering System 조건, 조성 및 시효 처리에 따른 광자기적 특성과 산화 특성을 조사하였다. XPS와 AES를 통하여 보호막 없이 제조된 TbFeCo 박막의 표면에는 Co에 우선하여 Tb과 Fe가 안정한 산화물의 형태로 존재하며, 표면에서 3.2nm 깊이부터는 산화되지 않은 TbFeCo 박막이 존재함을 확인하였다. TbFeCo 박막을 시효 시킴에 따라 Fe 산화층의 두께는 거의 변화가 없었으며, Tb Oxide 층만이 증가하였다. TbFeCo 박막은 사용된 기판의 종류나 제조조건에 따라 열적 안정성에 큰 차이를 보였다.

• Korean Journal of Materials Research
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• v.6 no.5
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• pp.470-474
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• 1996

증착법을 이용해 증착시 기판의 온도를 변화시키면서 MnSbPt 합금 박막을 만들고 이를 열처리 한 후 나타나는 자기 및 자기광학적 성질을 조사하였다. Mn45Sb45Pt10조성의 박막에서 0.85$^{\circ}$의 높은 Kerr Rotation Angle값을 나타내고, 또한 광원의 입사파장이 단파장으로 이동하여도 우수한 Kerr Rotation Angle 값을 유지함으로써 자기광 재료로서의 기록밀도 향상가능성이 기대된다. 이 재료가 갖고 있는 열악한 자기적성질도 열처리를 통하여 포화자화값과 보자력의 향상 효과를 얻었지만, 자기광 재료가 갖추어야할 수직자화를 얻기에는 미흡하여 이에 대한 보완이 필요하다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.206-210
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• 1998

A study on dynamic characteristics of rotating disks in magneto optical disk drives is presented. Natural frequencies of rotating disks are investigated experimentally and numerically. The frequency response and critical speeds of the ASMO disk are discussed. The characteristics of airflow around the disk and their effects on disk vibrations are also investigated. It is found that the numerical calculation of the natural frequencies of rotating disks agrees well with the experimental results. The airflow around the disk in the cartridge affects the characteristics of the disk vibrations to reduce the modal frequencies of the disk. The experiment shows that negative vertical offsets of the disk in the cartridge possibly increase the vibration amplitudes. As being influenced by the geometry of the cartridge, the rotation of the disk causes an asymmetric airflow in the presence of window.