• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2006.05a
• /
• pp.327-330
• /
• 2006

Numerical simulations were carried out to investigate the base drag characteristics of a base bleed projectile with a central propulsive jet by considering the base homing process. Overall fluid dynamic process is modeled by Wavier-Stokes equations for reacting flows with two-equation $k-\omega$ SST turbulence closure. The combustion process is modeled by finite-rate chemistry with a given partially burned exit condition of the BBU (base-bleed unit). Besides the demonstrating the capability of the present CFD solver for the base drag and the interaction of the base flow with a rocket plume, present study gives an insight into the fluid dynamics and the combustion process of the hybrid-propulsion projectile.

• Journal of the Korean Magnetics Society
• /
• v.8 no.4
• /
• pp.216-223
• /
• 1998

DC magnetron sputtering 방법에 의해 Corning glass 가판 위에 제작한 buffer/[CoFe/Cu]N 형태의 다층작막에 대하여 자기저항비의 비자성층 Cu두께, 기저층 종류(Fe, Cu, Cr, Ta)와 두께, Ardkqfur, 다층 층수 및 열처리 의존성을 조사하였다. 자기저항비는 비자성층 Cu 두께에 따라 진동하였다. 기저층 Fe 및 Cr의 두께가 60$\AA$이고, 층수 N=15, Ardkqfur 5mTorr에서 극대자기저항비 14%를 보였으며 25$0^{\circ}C$까지의 시료에 대한 열처리는 다층박막의 주기성을 유지한 채 더 큰 결정립을 갖게 하여 자기저항비는 증가하였으나 그 이상의 온도에서는 계면 혼합 및 계면 확산에 의한 감소를 나타내었다. Cr기저층 시료가 Fe 기저층 시료보다 열적안정성이 더 좋은 것을 알 수 있었다.

• Journal of the Korean Magnetics Society
• /
• v.7 no.2
• /
• pp.82-89
• /
• 1997

Dependence of magnetoresistance on the thickness of Cu, type and thickness of buffer layer, and the stacking number of multilayer in the form buffer /$[Co(17{\AA}/Cu(t{\AA})]_{20}$ were investigated. To evaluate effect of annealing on this samples, X-ray diffraction analysis, vibrating sample magnetometer analysis, and magnetoresistance measurement (4-probe method) were performed. The magnetoresistance ratio exhibits a maximum of 21% for the multilayer with Cu thickness of 24$\AA$ and Fe buffer layer thickness of 50$\AA$. Deposition of film under low base pressure induces in increase magnetoresistance ratio by preventing oxidation. The multilayer annealed below 30$0^{\circ}C$ temperature allowed larger textured grain without loss in the periodicity. Magnetoresistance ratios of the multilayer with Cu thickness of 24$\AA$ and 36$\AA$ were increased due to the increase in the antiferromagnetically coupled fraction after annealing.

• Journal of the Korean Magnetics Society
• /
• v.3 no.4
• /
• pp.310-313
• /
• 1993

The effect of Ni content in Cu underlayer on the magnetoresistance of Cu/Co artificial superlattice has been investigated. As the content of Ni increased, the preferred orientation of artificial superlattice changed from fec (100) to fcc (111) due to the change of the preferred orientation of the underlayer. When the content of Ni was 6 %, 26.7 % of magnetoresistance with 175 Oe of saturation field could be obtained in ${[Cu(19\AA)/Co(30\AA)]}_{20}|Cu-6%Ni(200\AA)/Si$.

• Journal of the Korean Vacuum Society
• /
• v.5 no.3
• /
• pp.258-262
• /
• 1996

We have investigated the changes in magnetoresistive characteristics, interfacial roughness, and preferred orientation with the Fe buffer layer thickness, annealing temperature, and the stacking number of layers variation in Fe/[NiFe/Cu] multilayers by using the 3-gun d.c. magnetron sputtering method. Intensity of the (200) orientation was increased with the increment of the Fe-buffer layer thickness. We found a maximum magnetoresistance ration of 4.7%, when the buffer layer thickness was 70$\AA$, and the field sensitivity also showed a maximum value at the same thickness. We varied the stacking number of multilayers with fixing the Fe buffer layer thickness of 70$\AA$. When the stacking number was 40 layers, maximum MR ratio(5.3%) was observed. With the variation of annealing temperature no change in the MR ratio was found beyond $300^{\circ}C$. But decrement of MR ratio was observed above $300^{\circ}C$. This decrement of the MR ratio was responsible for the increment of paramagnetic mixed layer caused by the diffusion of Cu layer and the change of antiferromagnetic coupling.

• The Journal of Engineering Geology
• /
• v.5 no.3
• /
• pp.259-276
• /
• 1995

Electrical soundings and profilings were conducted for mapping the leachate in the region of Nanji - Do Landfill site. The results of electrical surveys conducted in the landfill area show that the basal leachate is formed at the height about 30 m above the mean sea level and that there is abundant floating leachate over the basal leachate. The surveys conducted around the landfill reveal that the groundwater which may be contaminated by the leachate from the landfill flows to the Han River. The top of the basement rock in this area has been severely affected by polluted groundwater. The layer which is thoroughly saturated with leachate in this region has the very low resistivity value below 10 ohm - m and this low resistivity value indicates that the groundwater and geology are severely contaminated by the leachate and wastes of the landfill.

• Journal of the Korean Vacuum Society
• /
• v.4 no.S1
• /
• pp.87-91
• /
• 1995

초고집적회로의 배선 금속으로 사용되는 알루미늄 합금은 치밀한 표면 산화막 때문에 화학증착법에 의하여 비어를 선택적으로 충전하기 힘들다. 본 연구에서는 기저층을 이용하여 비어에 선택적으로 화학증착함으로써 평탄화를 이루는 새로운 방법을 제안하였다. 알루미늄, 구리 등의 배선 금속, 팔라듐, 코발트 등의 금속, 기타 타이타늄 질화물 등의 기판에 대하여 화학증착 알루미늄의 특성과 실리콘 산화물간의 선택성을 평가하였으며 팔라듐, 코발트, 타이타늄 질화물 등을 기저층으로 사용한 경우에 낮은 비저항과 안정적인 선택적 비어 충전을 이룰 수 있었다.

• Proceedings of the Korean Magnestics Society Conference
• /
• 1993.11a
• /
• pp.106-107
• /
• 1993

• Proceedings of the Korean Magnestics Society Conference
• /
• 1995.05a
• /
• pp.96-97
• /
• 1995

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.43 no.2 s.344
• /
• pp.34-41
• /
• 2006

This paper presents a CMOS multi-mode baseband filter architecture to support PDC/GSM/EDGE/WCDMA and its new automatic tuning method. 5-th order Chebyshev low pass filter is designed for implementing the baseband channel-select filter. Capacitors and resistors were shared efficiently between modes to minimize the area. And, the new cut-off frequency tuning method is proposed to compensate the process variation. This method can reduce the area and the noise level due to MOS switches.