• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.75-78
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• 2004

$Bi_{3.25}Eu_{0.75}Ti_3O_{12}$ (BET) thin films were deposited on the $LaNiO_3$ (LNO (100))/Si and Pt/Ti/$SiO_2$/Si substrates by the metal-organic decomposition method. Structural and dielectric properties of BLT thin films for the applications in nonvolatile ferroelectric random access memories were investigated. Both the structure and morphology of the films were analyzed by x-ray diffraction (XRD) and atomic force microscope (AFM). Even at low temperatures $650^{\circ}C$, the BET thinfilms were successfully deposited on LNO bottom electrode and exhibited (001) and (117) orientation. Compared with the Pt electrode films, the BET thin films on the LNO electrode annealed at $650^{\circ}C$ showed better dielectric constantsand remanent polarization. The BET thin films on the LNO electrode for the annealing temperature of $650^{\circ}C$, the remanent polarization Pr and coercive field were $45.6\;C/cm^2$ and 171 kV/cm, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.352-355
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• 2003

[ $Bi_{3.25}La_{0.75}Ti_3O_{12}$ ] (BLT) thin films were prepared by using metal organic decomposition method onto the LaNiO3 (LNO) bottom electrode. Both the structure and morphology of the films were analyzed by x-ray diffraction (XRD) and atomic force microscope (AFM). Even at low temperatures ranging from 450 to $650^{\circ}C$, the BLT thin films were successfully deposited on LNO bottom electrode and exhibited (117) orientation. The BLT thin films annealed as low as $600^{\circ}C$ showed excellent ferroelectricity, higher remanent polarization and no significant degradation of switching charge at least up to $5{\times}10^9$ switching cycles at a frequency of 100 kHz and 5 V. For the annealing temperature of $600^{\circ}C$, the remanent polarization $P_r$ and coercive field were $23.5\;{\mu}C/cm^2$ and 120 kV/cm, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.66-66
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• 2007

Lead zirconate titanate (PZT) is one of the most attractive perovskite-type materials for ferroelectric random access memory (FRAM) due to its higher remanant polarization and the ability to withstand higher coercive fields. We first applied the damascene process using chemical mechanical polishing (CMP) to fabricate the PZT thin film capacitor to solve the problems of plasma etching including low etching profile and ion charging. The $0.8{\times}0.8\;{\mu}m$ square patterns of silicon dioxide on Pt/Ti/$SiO_2$/Si substrate were coated by sol-gel method with the precursor solution of PZT. Damascene process by CMP was performed to pattern the PZT thin film with the vertical sidewall and no plasma damage. The polarization-voltage (P-V) characteristics of PZT capacitors and the current-voltage characteristics (I-V) were examined by change of process parameters. To examine the CMP induced damage to PZT capacitor, the domain structure of the polished PZT thin film was also investigated by piezoresponse force microscopy (PFM).

• 열처리공학회지
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• 제8권2호
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• pp.149-154
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• 1995

The alloying of 6.5wt % Silicon in iron decreases the magnetization and the anisotropy and minimizes the iron loss noticeably. But it is very difficult to make thin sheets because of its poor ductility which is due to an ordering reaction (body centered cubic to CsCI type crystal structure). However the ordering reaction can be suppressed by rapid solidification method. The cooling rate of rapidly solidified Fe-6.5wt % Si alloy is about $10^3K/s$ and rapidly solidified structure are fine structure, cellular structure, dendrite and equiaxed grain from surface. The precipitates of $DO_3$ Phase emerges on $B_2$ matrix and the coercive force was 0.51 Oe (50cycle, 15KGauss) in Fe-6.5wt% Si alloy which was processed by heat treatment of $1150^{\circ}C$ for 1hr in high vacuum.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
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• pp.522-529
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• 2000

We present a new procedure to evaluate the residual life of 1Cr-1Mo-0.25V steel by reversible magnetic permeability. The method is based on the existence of the first harmonics in the differential magnetization around the coercive force. The apparatus is based on the detection of the voltage induced in a coil using a lock-in amplifier tuned to a frequency of the exciting one. Results obtained for the first harmonics and Vickers hardness on the aged samples show that the peak interval of reversible permeability and Vickers hardness decrease as ageing time increases. The correlation between Vickers hardness and the peak interval of the reversible permeability could well be used to evaluate the residual life of 1Cr-1Mo-0.25V steel, nondestructively.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 하계학술연구발표회 및 한.일 공동심포지엄
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• pp.194-194
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• 2003

As a result of the recent miniaturization an enhancement in the performance of thin film inductors and thin film transformers, there are increased demands for the thin films with high magnetic permeability in the high frequency range, high saturation magnetization, in high electrical resistivity, and low coercive force. In order to improve high frequency properties, we will investigate anisotropy field by shape and size of pattern. The Fe-Al-O thin films of 16mm and 1 $\mu\textrm{m}$ thickness were deposited on Si wafer, using RF magnetron reactive sputtering technique with the mixture of argon and oxygen gases. The fabricating conditions are obtained in the working partial pressure of 2mTorr, O$_2$ partial pressure of 5%, input power of 400W, and Al pellets on an Fe disk with purity of 99,9%. Magnetic properties of the continuous films as followed: the 4$\pi$M$\_$s/ of 19.4kG, H$\_$c/ of 0.6Oe, H$\_$k/ of 6.0Oe and effective permeability of 2500 up to 100㎒ were obtained. In this work, we expect to enhance effect of magnetic anisotropy on patterned of Fe-Al-O thin films.

• 안보군사학연구
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• 통권8호
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• pp.239-270
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• 2010

This thesis is to make an appropriate national defense policy of Republic of Korea through studying the Hegemony Strategy of United States. I searched the theory of hegemony. The hegemony was differently defined by the point of time and region. The strong power nations with the hegemony have been making efforts to maintain their hegemony everytime. I have conclusion that the presence of hegemony once emerged, it brought regional stability in place whether it is coercive or beneficial. The stability and instability of international order IS not exclusively dependent on hegemony. Even if the safety of hegemony cannot guarantee absolute stability of international order, there IS on doubt that the hegemony has enormous impact on that. According to the hegemonic theory, the history of mankind equals to the history of rising and falling hegemony. The international order was changed as the hegemony changes. The United States has been making efforts to maintain her global hegemony during the post cold-war era as well. Taking all these into consideration, relevant military strategy direction able to pursue national interest is that to make up for the relative weakness in the strategic environment. South Korea have to prepare security policy response as following. First, South Korea should build the military force equipped with advanced weapons in military technology sector and solidify military diplomatic relation able to form cooperative relation in wartime. Second, South Korea should make solid Alliance of Korea and U.S. Third, develop and maintain multilateral security cooperation of East Asia. Forth, we could realize that there are means that can neutralize opponent's strong point by seeking one or two and more asymmetry in the aspect of strategy, tactics, and means through asymmetric strategy. Than the military force of South Korea should develop into a force that is able to overcome to the traditional North Korea's threat and new type of conflicts. And the force should have sufficient strength and be deployed to effectively defend the Korean Peninsula. So, we need to establish a denial and defense system against any hostile neighboring country. Therefore, ROK military forces preparing for the future should try to construct a future military power to gradually establish enough strength for self-defense to prepare for a uncertain security environment and when the Korean Peninsula is unified in a future.

• 센서학회지
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• 제3권1호
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• pp.68-77
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• 1994

강자성체 자기저항 센서를 개발하기 위하여 70Ni-30Co 합금을 $10^{-6}$ Torr의 진공중에서 $250^{\circ}C$ 의 슬라이드 그라스 위에 두께 $600{\AA}$ 으로 진공 증착한 후 박막을 격자형으로 식각하고 인출선을 연결하였다. 이와 같은 과정으로 제작된 센서의 자기저항 변화율에 미치는 온도, 저항, 선폭 등의 영향을 조사하고 보자력, 포화자화, 최대유효감도, 지연시간, 회전율, 백색잡음, 분해능 등을 조사 분석한 결과, (70Ni-30Co) 합금을 기판온도 $250^{\circ}C$ 에서 두께 $600{\AA}$ 으로 진공 증착하면 결정자기 이방성이 형성되어 자기저항 소자로써의 기능이 자발적으로 구비되면서 230 nT 의 최대유효감도가 구비됨을 확인하였다. ${\pm}10$ Oe 의 자장구간에서는 직선적인 자기저항변화를 보였으며, 센서소자를 형성하는 격자선의 폭에 대한 길이의 비가 클수록 자기저항 값이 증가함을 알 수 있었다. 한편 센서 소자와 인출선을 인듐으로 연결시키면 저항온도계수가 $8{\times}10^{-3}/deg$로 증가되어 센서 본연의 저항온도계수($1{\times}10^{4}/deg$)가 매우 심하게 열화된다는 것을 알 수 있었다. 이 실험에서 제작된 강자성박막(70Ni-30Co)의 특성은 보자력이 5.1 A/cm이고 포화자화가 0.64T 이었는데, 이 박막으로 제작한 자기저항 센서의 지연시간은 $5{\mu}s$이었고 회전율(slew rate)은 0.39 $Oe/{\mu}s$ 이었으며 백색잡음은 -120 dB 정도이었다.

• 한국자기학회지
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• 제10권5호
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• pp.210-219
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• 2000

질화철(FeN)막을 이용한 FeN/Co/Cu/Co와 FeN/Co/Cu/Co/Cu/Co/FeN 다층막의 자기저항효과를 조사하였다. 질소유량이 0.4 sccm 이상인 조건에서 제작한 FeN막의 결정구조는 $\alpha$-Fe와 $\varepsilon$-Fe$_3$N상의 혼합상이며 침상구조인 $\varepsilon$-Fe$_3$N상에 의해 유도되는 형상자기이방성 때문에 자기저항효과가 관찰된다. 자기저항효과는 FeN막의 질소 유량과 두께에 따라서 달라지며 이는 FeN막의 $\varepsilon$-Fe$_3$N상에 의해 유도되는 형상자기이방성이 자유층과 고착층에 미치는 범위가 질소유량과 두께에 따라 달라지기 때문이다. 자유층인 Co막의 두께가 70 $\AA$인 조건에서 가장 우수한 자기저항비와 자기저항감도를 나타내며 자기저항비는 질소유량이 0.5 sccm이고 두께가 250 $\AA$인 조건에서 제작된 FeN/Co/Cu/Co/Cu/Co/FeN 다층막에서 3.2 %로 최대값을 나타낸다. 이 다층막의 3개의 자성층은 각기 다른 보자력을 갖고 있으므로 자기저항곡선상에 각각의 보자력 차이에 의한 step을 형성하며 MRAM 등으로 응용시 4개의 신호를 동시에 구현할 수 있을 것으로 기대된다.

• 한국자기학회지
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• 제2권3호
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• pp.244-250
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• 1992

고밀도 자기기록 매체인 iron carbonitride는 출발물질인 iron oxalate$(FeC_2O_4{\cdot}2H_2O)$를 암모니아-수소 혼합 분위기 상태에서 질화함으로써 제조되었다. 또한 carbonitride 결정의 형태는 출발물질의 제조조건에 의존하며, 이의 침전반응 조건은 $60^{\circ}C,$ 30분이 가장 적당하였다. Fe일부에 대한 Sn의 치환은 입자성장을 억제하고, 침상성을 증가시키는 효과가 있었다. 전자현미경 관찰결과, 질화철 입자는 많은 미세한 단위입자들이 입체망목적으로 연결되어 있었으며, 이 단위입자는 단자구 정도의 크기로 관찰되었다. 이때 보자력과 포화자화는 각각 500 Oe, 120 emu/g 이었다.