• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.555-556
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• 2006

In recent years, the higher flatness level in wafer shape has been strictly demanded with a high integration of the semiconductor devices. It has become difficult for a conventional wafer preparing process to satisfy those demands. In order to meet those demands, surface grinding with in-feed grinder is adopted. In an in-feed grinding method, a chuck table fur fixing a semiconductor wafrr rotates on its rotation axis with a slight tilt angle to the rotation axis of a cup shaped grinding wheel and the grinding wheel in rotation moves down to grind the wafer. So, stability of the grinder structure is very important to aquire a wafer of good quality. This paper describes the features of the in-feed grinder and some FEM analysis results of the grinder structure.

• Journal of the Korean Magnetics Society
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• v.4 no.3
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• pp.244-248
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• 1994

Magnetic and Magneto-optical characteristics of NdTbFeCo alloy films and NdTbFeCo/TbFeCo double-layered films have been investigated. It was observed that the Kerr rotation(${\theta}_{k}$) in the short wavelength region increased and the coercivity decreased as the substitutional amount of Nd for Tb in NdTbFeCo film at the constant FeCo content. In spite of the increased ${\theta}_{k}$, a small coercivity of NdTbFeCo film made this medium unsuitable for magneto-optical recording medium at short wavelength. An effort was made to improve coercivity by exchange coupling with TbFeCo film of high coercivity. In the exchange-coupled $Nd_{16.9}Tb_{15.2}Fe_{50.4}Co_{17.5}(150\;{\AA})/Tb_{21.1}Fe_{65.0}Co_{13.9}(300\;{\AA})$ double-layered film, the magnetization reversal switching field and the Kerr rotation angle were increased to about 6.0 KOe and $0.32^{\circ}$ at 500 nm, respectively. This result indicates that exchange-coupled NdTbFeCo/TbFeCo film can be a promising candidate for agneta-optical rerding medium short wavelenhth.

• Korean Journal of Applied Biomechanics
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• v.30 no.3
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• pp.217-223
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• 2020

Objective: The purpose of this study was to analyze the effect of postural sway on the kinematic variables of the putter head during golf putting and to provide information to the importance of postural sway control in the putting stroke for novice golfers. Method: The center of pressure (CoP) and Kinematics variables of the putter head were calculated during 2 m flat golf putting using 8 motion capture cameras (250 Hz) and 2 force plate (1,000 Hz). SPSS 24.0 was used to perform Pearson's correlation coefficient and simple regression analysis, and the statistically significance level was set to .05. Results: As a result of analyzing the correlation between CoP variables and the putter head rotation angle, the CoP moving length, CoP moving range (ML direction), and CoP moving velocity (ML direction) showed a positive correlation with the putter head rotation angle (yaw axis) and were statistically significant. Conclusion: Therefore, In order to perform the accurate putting stroke maintaining the ball's directionality, it is determined that it is important to control posture sway in the ML directions by minimizing the movement and velocity of the CoP.

• Radiation Oncology Journal
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• v.21 no.2
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• pp.174-181
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• 2003

Purpose: The target volume for the three field technique in breast cancer include the breast tangential and supraclavicular areas. The techniques rotating the gantry and couch angles, to match these two areas, will geometrically produce mismatching of the posterior edge between the medial and lateral tangential beams. This mismatch was confirmed by film dosimetry and three-dimensional computer planning. The correction methods of this mismatching were studied in this article. Materials and Methods: After the supraclavicular field was simulated using a half beam block and the medial and lateral tangential fields, by the rotation of the couch and gantry, we compared the following two methods to correct the mismatch. The first method was the rotation of coillmator until a line drawn on the posterior edge of tangential beams before the rotation of couch aligned the line drawn on the posterior edge after the rotation. The second method was the rotation of collimator according to the formula developed by the author as follows; Co=$2sin^{-1}${$sin\{theta}\{cdot}sin(C/2)$} (Co: collimator angle, $\theta$: angle between tangential beam and table, C: couch angle) Results: The film dosimetry showed the mismatching of posterior edges of the medial and lateral tangential fields prior to the rotation of collimator, while the posterior edges matched well after the rotation of collimator according to the formula. The three-dimensional computer plan also showed that the posterior edges matched well after the rotation of collimator accordingly. The DVH of the ipsilateral lung with the proper rotation of collimator angle was better than that without the rotation of collimator angle. Conclusion: The mismatching of the posterior edges of the medial and lateral tangential fields can be recognized on the three fileld technique in breast irradiation when the gantry and couch are simultaneously rotated and can be corrected with the proper rotation of the collimator angle. The radiation dose to the ipsilateral lung could be lowered with this technique.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.2
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• pp.62-67
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• 1999

Phase rotational is a practical problem in the implementation of coherent demodulation. Large phase noise may intorduce phase rotation in the demodulator which results in repeated decision errors. This paper presents a simple and yet very efficient technique in building a carrier recovery loop which minimizes the phase rotation by improving the stability of the decision-directed carrier recovery loop. Simulation shows this novel technique improves the performance of the carrier recovery loop as well as stability.

• Journal of Power System Engineering
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• v.20 no.2
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• pp.26-31
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• 2016

The studies on the efficient ventilator to reduce fire and save energy have been proceeded actively. The purpose of this paper is to design a ventilator used in residential wood stove. The ventilator consists of rotation and support part, and it is operated by natural wind without power. The shape of rotation part of the ventilator is like airfoil to reinforce pressure drop. We designed direction controller for the rotation part to track the direction of wind continuously. The rotation and support part have point-contact each other to minimize a friction. We verify the properties of the proposed ventilator though simulation and experiment. The results show the proposed ventilator can exhaust safely combustion gas of the stove more than other ventilator.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.154-159
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• 1994

The magneto-optical Kerr spectra(${\lambda}=250~700nm$) of amorphous RE-Co(RE=Ce, Nd, Pr, Gd, Tb, Er, Ho) are compared with those of Y-Co films. It has been found that the Kerr rotation of RE-Co is mainly due to Co in the long wavelength region, whereas at short wavelength Ce, Pr, Nd, and Gd contribute positively, and Tb, Ho, and Er contribute negatively to the Kerr rotation of RE-Co amorphous films. In the interesting energy region(1.5~5.0 eV), the magneto-optical contribution of Pr and Nd are thought to be related with $4f{\uparrow}->5d{\uparrow}$ interband transition, and the contribution of Ce and Gd might be concerned with d->p interband transition. The magneto-optical effect of Tb in the short wavelength region might be related with $4f{\downarrow}->5d{\downarrow}$ and/or $5d{\downarrow}->4f{\downarrow}$, and that of Ho and Er can be explained by $4f{\downarrow}->5d{\downarrow}$ magneto-optical interband transition.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.251-251
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• 2012

A lot of studies are undergoing on the magneto-optical (MO) properties of patterned magnetic systems for the reason that they have potential application to information technology such as ultrahigh-speed computing. Moreover, they can be considered as the future candidates for high-density MO storage devices. Not only the technical aspects, but there have been also tremendous interests in studying their properties related to the fundamental physics. The MO Kerr-rotation effects (both in reflected and the diffracted modes) and the magnetic force microscopy (MFM) are very useful techniques to investigate the micromagnetic properties of such periodic structures. Hence, in this study, we report on the MO properties of bilayered Cobalt (Co)/ nickel (Ni) micro-patterned anti-dot arrays. Such a ferromagnetic structure was made by sequentially depositing co (40 nm)/Ni (5 nm) bilayer on a Si substrate. The anti-dot patterning with hole diameter of $1{\mu}m$ was done only on the upper Co layer using photolithography technique, while the Ni underlayer was kept uniform. The longitudinal Kerr rotation (LKR) of the zeroth- and the first-order diffracted beams were measured at an incidence of $30^{\circ}$ by using a photoelastic modulator method. The external magnetic field was applied perpendicularly to the reflected and the diffracted beams using an electromagnet capable of a maximum field of ${\pm}5$ kOe. Significantly, it was observed that the LKR of the first-order diffracted beam is nearly 4 times larger than that of the zeroth-order beam. The simulated results for the hysteresis loops matched qualitatively well with the experimentally obtained ones. In conjunction with the LKR, we also investigated the magnetic-domain structure by using a MFM system, which were analyzed to elucidate the origin of the enhanced MO rotation.

• Journal of the Korean Magnetics Society
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• v.2 no.1
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• pp.61-68
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• 1992

Structural, magnetic and magneto-optical(1.0~3.2eV) properties of rare earth (Ce, Pr, Eu), transition metal(Ni, Co), and Al substituted polycrystalline Ba ferrite films grown by rf sputtering have been investigated. TEM studies revealed that crystal grains in the films were reduced in size from several hundred nm to the order of 1 nm with the decrease of rf power density during sputtering. By substituting Al, square hysteresis loops have successfully been obtained. It has been found that Niions strongly enhances Faraday rotation of the films in the visible range. It has been confirmed that Co ions also strongly enhances Faraday rotation of the films in the near infrared. En- hancement in Faraday rotation by Ce, Pr, and Eu ions has not been observed. The origin of the enhancement in magnetic and magneto-optical properties of the films is discussed.

• Journal of Magnetics
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• v.1 no.2
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• pp.86-89
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• 1996

The dc magnetron sputter deposited (Pt/Co/Pt/Ni) multilayers which exhibited Curie temperatures in the range of 150-$300^{\circ}C$ were studied as possible alternative multilayers for magneto-optical recording to the widely studied Co/Pt, whose Curie temperatures are in the range of 200~$400^{\circ}C$. The Coercivities of these multilayers were between 450 Oe and 800 Oe. These multilayers exhibited comparable magnetic and magneto-optical properties to Co/Pt multilayers with enhancement of the Kerr rotation at lower wavelengths and negligible Kerr ellipticity over a wide range of the spectrum (4000~7000$\AA$ ).