• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.9-10
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• 2000

The wide viewing angle and fast response time characteristics of negative dielectric anisotropy nematic liquid crystal (NLC) using a novel vertical-alignment (VA) - 1/4 ${\pi}$ cell mode on a homeotropic alignment layer were investigated. Good voltage-transmittance curves and low driving voltage using the novel VA - 1/4 ${\pi}$ cell mode without a negative compensation film were obtained. The iso-viewing angle characteristics of NLC using the novel VA - 1/4 ${\pi}$ cell mode without a negative compensation film can be achieved. The fast response time of 24.4 ms in NLC was successfully measured. The iso-viewing angle, fast response time, and low driving voltage characteristics using the novel VA - 1/4 ${\pi}$ cell mode can be achieved.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.5
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• pp.496-500
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• 1991

The effects of annealing with and without magnetic field on magnetic properties of amorphous Fe-B-Si cores have been investigated as a function of toroidal stress. By decreasing the toroidal stress, the magnetic properties of the amorphous ribbon have beenimproved. Near 180 domain walls exist in the thermally annealed toroidal cores, but the domain walls exist in the thermally annealed toroidal cores, but the domain walls are not parallel to the longitudinal direction of the ribbon. In the specimen annealed with a magnetic field strength of 10 Oe in the longitudinal ribbon length axis, the domains are nearly parallel to the longitudinal direction due to the field induced uniaxial anisotropy resulting in further increase in the remanent magnetization and decrease in the coercive force and loss.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.4
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• pp.332-336
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• 2000

We have developed a novel vertical-alignment(VA) -$\pi$ cell mode that provides a wide viewing angle and fast response times for nematic liquid crystal(NLC) with negative dielectric anisotropy on a homeotropic polymide(PI) surfaces. Good voltage-transmittance curves and low driving voltages were achieved with the new VA-$\pi$ cell mode without a negative compensation film. Iso-viewing angle characteristics using the new VA-$\pi$ cell mode without a negative compensation film was also successfully observed. As well a fast response time of 31.7 ms for a new VA-$\pi$ mode was measured. Consequently the iso-viewing angel fast response time and low driving voltage characteristics using a VA-$\pi$ cell can be achieved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.191-194
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• 1998

This Paper present a new structure for a piezoelectric transformer, operating in thickness extensional vibration mode. Modified PbTiO$_3$ family ceramics were used for the Piezoelectric transformer, because it is a material with large anisotropy between electromechanical coupling facters k$\sub$t/ and k$\sub$p/. Piezoelectric transformer was fabricated that is 20mm long, 20mm wide and 3.1mm thick. Resonant frequencies of sencond thickness extensional vibration mode is 1.72MHz at loading resistance 100{$\Omega$]. And Voltage gain of piezoelectric ceramics is showed 0.53 at resonant frequency of sencond thickness extensional vibration mode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.630-633
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• 1999

This paper presents a new sort of multilayer piezoelectric ceramice transformer for switching regulatied power supplies. And this paper presents the study and development of a DC-DC converter with a transformer made from piezoelectric materials. This piezoelectric transformer operate, in the second thickness extensional vibration mode. Its resonant frequency is higher than 1MHz, This piezoelectric transformer was used the PbTiO$_3$ family ceramics because it was a material large anisotropy between electromechanical coupling factors k$_{t}$ and k$_{p}$. The input and output layer consists of two piezoelectric ceramic layer for eleivater of outpur power.wer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.855-860
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• 1998

This paper presents a new structure for a piezoelectric transformer, operating in thickness extensional vibration mode. Modified $PbTiO_3$ family ceramics were used for the piezoelectric transformer, because it was a material with large anisotropy between elecromechanical coupling factors $K_t$ and $K_p$ . The size of piezoelectric transformer was 20mn long, 20mm wide and 3.1mm thick. The second harmonic resonant frequency of thickness extensional vibration mode was 0.72MHz at loading resistance 100[$\omega$], And Voltage gin of piezoelectric ceramics showed 0.53 at resonant frequency of sencond thickness extensional vibration mode.

• Electrical & Electronic Materials
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• v.9 no.10
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• pp.1060-1065
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• 1996

We have studied the magnetoresistance phenomena on spin valve thin films of antiferromagnetic NiO/CoO. Interlayer coupling oscillates between the antiferrocoupling and ferrocoupling with the variation of Cu thickness. The exchange coupling strength between NiO (antiferromagnetic) and NiFe(ferromagnetic) as a function of NiO texture and interface roughness is investigated by CoO insertion. CoO has significantly higher anisotropy in the (111) plane and interface roughness. It seems that the MR-ratio is increased by CoO inserted films. From the AFM and XRD data, the increase of MR-ratio and exchange field is influenced by the roughness of CoO.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.47-49
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• 1988

This paper discusses dynamic properties of bubble garnet thin films. The dynamic properties considered are Gilbert damping parameters, saturation velocity, and wall mobility. The parameters are evaluated to facilitate the search for desirable garnet thin film compositions. Given bubble diameter and Q-value, the computer prints out all compositions which meet the desired requirements. The computer model determines magnetization, anisotropy, damping, velocity, mobility among others from the film compositions. The computer modeling program is described by an algorithm detailing its operation.

• Electrical & Electronic Materials
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• v.7 no.4
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• pp.294-299
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• 1994

CHF$_{3}$/CH$_{4}$Ar 플라즈마에 의해 형성된 산화막 식각 잔류물의 화학구조와 이 잔류물의 제거를 위한 세정방법을 x-ray photoelectron spectroscopy를 이용하여 조사하였다. 잔류무르이 구조는 CF$_{x}$-polymer와 Si-C, Si-O 결합으로 이루어진 SiO$_{y}$ C$_{z}$ 이었다. CF$_{4}$O$_{2}$ 플라즈마에 의한 silicon light etch는 산화막 식각 잔류물인 SiO$_{y}$ C$_{z}$ 층과 손상된 실리콘 표면을 제거하엿으며 NH$_{4}$OH-H$_{2}$O$_{2}$과 HF용액으로 완전히 제거되는 CF$_{x}$-polymer/SiO$_{x}$층을 남겼다. 100.angs.정도의 silicon light etch는 minority carrier life time과 thermal wave signal값을 초기 웨이퍼 수준까지 회복시켰으며 접합누설 전류도 거의 습식 식각 공정수준까지 감소시켰다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.8
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• pp.652-657
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• 1998

We have performed spin-spray ferrite plating of $Fe{_3}{-X}-Ni_XO_4$(X=0.17~0.26) films in the temperature region $T=80~95[^{\circ}C]$. A reaction solution and an oxidizing solution were supplied to a reaction chamber by supply pump. The solubility limit of Ni increases as the substrate temperature increase, from X=0.17 at $80[^{\circ}C]$ to X=0.26 at $95[^{\circ}C]$. All the films are polycrystalline with no preferential orientation, and the magnetization exhibits no definite anisotropy. Grain size in the films increases as X increases, reaching $0.87[\mu{m}]$ at X=0.26.