• Proceedings of the Korean Society of Crop Science Conference
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• 2018.04a
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• pp.44-44
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• 2018

• Proceedings of the Korean Society of Crop Science Conference
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• 2018.04a
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• pp.45-45
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• 2018

• Korean Journal of Materials Research
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• v.4 no.2
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• pp.233-240
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• 1994

We have investigated how the magneto-optical and recording properties of Pt/Co modulated films vary with sample preparation conditions : sputtering at various gas pressures, sputtering with Xe instead of Ar, and etching the buffer layers, etc. The magneto-optical characteristics of Pt/Co multilayers was comparable with those of currently prevailing rare-earth transition-metal alloys(Tb-Fe-Co amorphous films). On a disk of $12{\times}[Pt10.7\;{\AA}/Co2.8{\;}{\AA}]$ multilayer enhanced with 70nm silicon nitride, we have achieved a CNR of 36dB with a reading laser(${\lambda}\;=\;780nm$) power of 2.5-4.5mW for 720KHz carrier at 1.4m/s and the enhanced kerr rotation angle of $1.23^{\circ}$ at 780nm. It is suggested that Pt/Co modulated films clearly are very promising magneto-optical materials for a commercially use.

• Korean Journal of Cognitive Science
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• v.15 no.2
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• pp.23-31
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• 2004

Latent Semantic Analysis (LSA Landauer ＆ Dumais, 1997) is a technique to represent the meanings of words using co-occurrence information of words appearing in he same context, which is usually a sentence or a document. In LSA, a word is represented as a point in multidimensional space where each axis represents a context, and a word's meaning is determined by its frequency in each context. The space is reduced by singular value decomposition (SVD). The present study elaborates upon LSA for use of representation of ambiguous words. The proposed LSA applies rotation of axes in the document space which makes possible to interpret the meaning of un. A simulation study was conducted to illustrate the performance of LSA in representation of ambiguous words. In the simulation, first, the texts which contain an ambiguous word were extracted and LSA with rotation was performed. By comparing loading matrix, we categorized the texts according to meanings. The first meaning of an ambiguous wold was represented by LSA with the matrix excluding the vectors for the other meaning. The other meanings were also represented in the same way. The simulation showed that this way of representation of an ambiguous word can identify the meanings of the word. This result suggest that LSA with axis rotation can be applied to representation of ambiguous words. We discussed that the use of rotation makes it possible to represent multiple meanings of ambiguous words, and this technique can be applied in the area of web searching.

• Atmosphere
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• v.22 no.2
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• pp.279-285
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• 2012

The weighing precipitation gauge with auto-empting capability was developed in the R&D project organized by the Research Agency for Climate Science (RACS) and supported by the Korea Meteorological Administration (KMA). This project was initiated in line with the KMA's plan executed since 2010 to introduce the weighing precipitation gauges partly into of their Automatic Weather Station (AWS) network in order to upgrade the quality of precipitation data. The innovative feature of this research is that the auto-empting in weighing precipitation gauge is realized by abrupt rotation of receiving container. The prototype was tested in compliance with the relevant standards of KMA. The results of performance test on rainfall measurement in laboratory verified that the accuracies for 20 mm and 100 mm reference rainfall amount were 0.1 mm and 0.4 mm, respectively in both conditions of auto-empting and no-empting. During the rotation of container for auto-empting, the data was extrapolated smoothly by applying the same precipitation intensity of the previous 10 sec. Consequently, it was found that the auto-empting precipitation gauge developed in this research is quite enough to be used for the operational purpose of accurate measurement with 0.1 mm resolution, regardless of the precipitation intensity.

• Journal of Welding and Joining
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• v.24 no.1
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• pp.88-92
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• 2006

Laser-rotating arc hybrid welding was introduced by combining $CO_2$ laser and rotating gas metal arc welding. While the arc rotation enhances the weld pool motion, it reduces the undercut formation which is one of most critical weld defects in the conventional laser-arc hybrid welding. This research investigated the bead characteristics according to the welding parameters such as frequency of rotation, welding voltage, shielding gas composition and interspacing distance between laser and we. The welding parameters were selected to reduce spatter generation and ensure sound weld beads fur bead welding and butt welding with various joint gaps. Gap bridging ability was improved, such that the sound weld beads were achieved for butt joint with up to 2mm joint sap, with no adjustment of CTWD(Contact tip-to-workpiece distance) and electrode diameter.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.9
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• pp.809-816
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• 2010

An environmental control system is installed to dissipate the thermal load in avionic equipments that are mounted under an aircraft. The operating characteristics of the system change with variations in the control parameters. In this study, an environmental control system was designed and built using R-124 by adopting a vapor compression cycle. The operating characteristics of this system were observed by varying the control parameters, such as refrigerant charging amount, opening of the expansion device, compressor rotation speed, and blower rotation speed. The effect of the control parameters on the environmental control system was analyzed and an optimum control method was identified.

• Journal of Magnetics
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• v.14 no.1
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• pp.36-41
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• 2009

Magneto-optical Kerr effect (MOKE) magnetometry was used to investigate magnetization reversal dynamics in 30-nm NiFe/15-nm FeMn, 15-nm FeMn/30-nm CoFe bilayers, and 30-nm NiFe/(2,10)-nm FeMn/30-nm CoFe trilayers. The in-plane magnetization components of each ferromagnetic layer, both parallel and perpendicular to the applied field, were separately determined by measuring the longitudinal and transverse MOKE hysteresis loops from both the front and back sides of the film for an oblique incident s-polarized beam. The magnetization of the FeMn/CoFe bilayer was reversed abruptly and symmetrically through nucleation and domain wall propagation, while that of the NiFe/FeMn bilayer was reversed asymmetrically with a dominant rotation. In the NiFe/FeMn/CoFe trilayers, the magnetic reversal of the two ferromagnetic layers proceeded via nucleation and domain wall propagation for 2-nm FeMn, but via asymmetric rotation for 10-nm FeMn. The exchange-biased ferromagnetic layers showed the magnetization reversal along the same path in the film plane for the decreasing and increasing field branches from transverse MOKE hysteresis loops, which can be qualitatively explained by the theoretical model of the exchange-biased ferromagnetic/antiferromagnetic systems.

• Journal of the Korean Magnetics Society
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• v.4 no.4
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• pp.307-312
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• 1994

The magneto-optical Kerr effect due to the (Fe,Co)/(Pd,Pt,Cu,Ag) multilayer film is calculated considering of multiple reflection effect, and the calculated Kerr spectrum is compared to the reported experimental value. In case of Co/Pd, the reliance of composition and the variable tendency of magneto-optical Kerr rotation angle for Co thickness fully coresponds to experimantal and theoretical value. The theoretical Kerr spectrum of Fe/Cu and Fe/Ag multilayer films show the peaks near the Cu and Ag optical ansorption band in accordance with the experiment. But in case of Co/Pt, the increase tendency of Kerr rofation with decreasing wavelength reported by experiments could not be explained by the optical multiple interference. This difference of theoretical and experimental Kerr spectrum of Co/Pt film might be related with the change of electronic structure of Co and/or Pt from their bulk state.

• Journal of Welding and Joining
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• v.24 no.1
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• pp.43-49
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• 2006

This paper describes the friction surface modification which has been successfully developed with the friction stir welding recently There are several problems including just position control and backlash in conventional friction surface modification system. Therefore it has been developed the friction surface modification system which has been controlled precisely both position and force by driving hydraulic cylinder in this paper. The mechtrode rotation speed(N) and feeding speed(Vz), travel speed(Vx,y) are of critical importance for the width and thickness of the coating in friction surfacing process. But there is no theoretical method of determining interrelations between process parameters affect the coating width and thickness. As a result of DOE(design of experiment) with developed system, the coating thickness and width seemed to decrease according to increase the mechtrode rotation speed(N) and traveling speed(Vx,y), to decrease feeding speed(Vz) apparently. However as the result of regression analysis the main effect was only the mechtrode rotation speed in the coating thickness.