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Ferromagnetic Behavior above Room Temperature of Fe-Ion-Implanted ZnO
송영열,K.S Park,K.W Lee,유성초,신상원,강희재,황정남,D.V Son,J.H Lee,J.H Song 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.6
Zinc-oxide (0001) single crystals with a 0.5 mm thickness were prepared, and then 80 keV Fe ions with a dose of 3 $\times$ 10$^{16}$ ions/cm$^{2}$ were implanted into the ZnO single crystals at 350 $^\circ$C. The implanted samples were post-annealed at 700, 800 and 900 $^\circ$C by rapid thermal annealing in an N$_{2}$ atmosphere for 5 min to remove the ion-implantation damage. The structure and the magnetic properties of Fe-ion-implanted ZnO were investigated by using X-ray diffraction and a superconducting quantum interference device magnetometer. The carrier transport properties were measured in the range from 5 K to 300 K. The X-ray diffraction results showed an island peak near 37 $^\circ$C, which was identified as ZnO$_{2}$. The magnetization curve showed hysteresis loops at 5 K in the samples annealed at 700 and 800 $^\circ$C, showing ferromagnetism. Hysteresis loops were observed at 300 K in the samples annealed at 700 $^\circ$C. The temperature dependence of the magnetization was taken in field cooling (FC) and zero field cooling (ZFC) in the samples annealed at 700 $^\circ$C. The difference magnetization ($\Delta$\textit{M}) between the FC and the ZFC magnetizations did not converge to a zero value even at 340 K, showing ferromagnetism above room temperature. The magnetoresistance (MR) curve showed negative curvature up to 150 K which could be explained with the delocalized \textit{d} state of ZnO implanted with Fe ions
Ferromagnetism Above Room Temperature in Cr-Doped AlN Films
송영열,유성초,임기수,P. H Quang,Y. G. Yoo 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.6
Chromium-doped AlN .lms were prepared for a wide range of deposition parameters. The .lms were deposited on Si, Corning glass, and quartz substrates by magnetron sputtering. The single- phase .lms were obtained at an argon-nitrogen pressure of 6 mTorr for a substrate temperature range of 300 { 400 ±C. The .lms had typical thicknesses in the range of 200 { 1600 nm. The X-ray diraction pattern indicated a pure Cr-doped AlN phase. The concentration of Cr was deter- mined by using energy dispersive X-ray spectrometry (EDS) and X-ray photoemission spectrometry (XPS). The magnetization of the .lms grown on glass substrates was measured by using an alter- nating gradient magnetometer (AGM) system. The AGM data gave hysteresis loops with a small coercive force and a saturation magnetization, Ms of 0.1 emu/cm3. The Ms value is consistent with the literature values. The ferromagnetic resonance (FMR) spectra were measured from room temperature to 500 K at 9.2 GHz with the static .eld parallel to the .lm plane. The ferromagnetism was detected even at 500 K, which was the maximum temperature of our system. The optical ab- sorption gap determined by using Tsuc's method decreased from 6.18 eV to 4.74 eV with increasing Cr content from x = 0 to 0.25. This behavior can be attributed to the broadening of the impurity band, which is formed by the hybridization of p-d orbital. Transport properties were measured as a function of temperature from 77 K to 300 K by using the four-probe method. The data points satisfy the exponential law for variable range hopping in Cr doped AlN .lms.
송영열 안양대학교 사회과학연구소 1995 社會科學硏究 Vol.3 No.-
Abstract The government has decided to introduce the stock index futures in regard to KOSPI 200 starting from 1996. As futures markets are being opened, stock holders and would-be stock holders can hedge the risk of the variation of stock price with the use of futures markets. Future price can be found due to hight equity and trust as the participants in futures market collect, analyze and predict the information about stock price so that price of stock index futures can be done through price competition. It is expected that new investment means may be offered due to the profit rate corresponding to the investment principal as large-scale deals are available with pretty small margin. It is also predicted that liquidity may become enlarged and spot price may get settled with the active intervention of arbitragy traders using the temporary price difference between futures market and spot market. Therefore, these studies aim to promote the stable management and balanced development of stock market and stock index futures market and protect investors by examining how to make stock indices and investigating the pricing principle of stock index futures and the investment strategy with the use of stock index futures.
송영열 안양대학교 사회과학연구소 1996 社會科學硏究 Vol.4 No.-
This article is analyze the new challenge of WTO(world trade organization) and it's effect to korean economy. For this. First, this article is try to find out it's effect to korean economy and to korean business throught agreement. Second, this article is try to find out the commercial problems with the settlement of WTO. Third, this article is find out the influencement to korean industries with the WHO andto find out appropriate countermeasure.
대면적 임프린트 장비를 위한 LCD Glass 변형 시뮬레이션 연구
송영중(Youngjoong Song),신동훈(Donghoon Shin),임홍재(Hongjae Im),장시열(Siyeol Jang),이기성(Keesung Lee),정재일(Jayil Jeong) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
The purpose of the study is to simulate the displacement of the LCD glass during process of a large size imprint. During this process, a small temperature variation makes thermal stress, which causes the horizontal variation of mold and glass. During alig㎚ent process to fix the LCD glass on a alig㎚ent stage, the vertical displacement is made by the absorption pressure and the shear stress. This study simulates the horizontal displacement of mold and glass due to temperature variation, the vertical displacement depending on the shape of absorption surface fixing the LCD glass in the alig㎚ent process, and the horizontal and vertical displacement which occurs in the LCD glass at the alig㎚ent process. Algor which is a FEM code for a framework simulation was applied. Temperature variation above ± 0.1℃ on mold and glass causes the horizontal displacement of 150㎚ due to thermal expansion. The vertical displacement due to the circular is ten times of the case of rectangular absorption nozzle. The displacement of the LCD glass in the alig㎚ent process is about 49㎚.