• Proceedings of the Korean Vacuum Society Conference
• /
• 1999.07a
• /
• pp.105-105
• /
• 1999

차세대 기억소자에서는 집접도의 증가, 고속화, 그리고 미세화에 따라 배선간으 최소선폭이 작아지고, 새로운 다층 배선기술이 요구되는 가운데 층간절연막의 재료와 형성기술은 소자의 특성을 향상시켜주는 중요한 요소로서 열적안정성, 저유전율, 평탄화특성 등에 핵심을 두고 연구되고 있다. 본 연구에서는 5인치 p-Si(100) 위에 FTES와 O2를 precursor로 하고 carrier gas를 Ar gas하여 ICP CVD 방법으로 저유전율의 Fluorocarbonated-SiO2 박막을 형성하였다. 0.1-1kW, 13.56MHz인 rf power를 사용하였으며, 증착은 RT에서 5~10분으로 하였다. 형성된 박막은 FTIR(fourier transform infrared), XPS(x-ray photoelectron spectroscopy), 그리고 ellipsopsometer 등을 이용하여 결합모드와 F농도, 균일도 등을 측정하고, I-V와 C-V 측정장치, 그리고 SERM(scanning electrion microscopy) 등을 이용하여 유전상수, 누설전류, dielectric breakdown voltage, 그리고 박막의 stepcoverage를 측정하였다. 제작된 박막의 신뢰성은 열처리에 따른 전기적 특성으로부터 조사하였다. 형성된 fluorocarbonated 박막 결합모드는 Si-F, Si-O, O-C, C-C와 C-F였고 O2:FTES:Ar 유량을 1sccm:10sccm:6sccm으로 하여 증착한 시료에서 유전율은 2.8이었으며, 누설전류밀도는 8$\times$10-9A/cm2, Breakdown voltage는 10MV/cm 이상, 그리고 stepcoverage는 91%로 측정되었다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.1
• /
• pp.1-8
• /
• 2015

In this paper, a double-input single-output architecture of a LNA(Low Noise Amplifier) is presented to enable to be devised for light weight and small-sized OTM(On-The-Move) satellite communication system suitable to be mounted on vehicles. In spite of advantages of the double-input single-output architecture of a LNA such as reduction of the number of physical channels, it results in time-varying phase error between a fundamental mode path and a high-order mode path. This paper shows that the error can be corrected by adding pilot signals to the LNA and using signal processing, and also gives the measurement data to use the method mentioned above.

• Journal of Broadcast Engineering
• /
• v.24 no.1
• /
• pp.41-47
• /
• 2019

Recently, enhanced methods on the inter merging have been being investigated in Versatile Video Coding (VVC) standardization which will be a next generation video coding standard with capability beyond the High Efficiency Video Coding (HEVC). If there is not enough motion information available in the neighboring blocks in the merge mode, zero motion candidate is inserted into the merge candidate list, which could make the coding efficiency decreased. In this paper, we propose an efficient method of constructing the merge mode candidate list to reduce the case that the zero motion is used as a candidate by generating an alternative merge candidate. Experimental results show that the proposed method gives the average BD-rate gain of 0.2% with the decoding time increase of 3% in the comparison with VTM 1.0.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.19 no.1
• /
• pp.1-7
• /
• 1999

In order to determine the mode I stress intensity factor ($K_I$) by means of the alternating current potential drop(ACPD) technique, the change in potential drop due to load for a paramagnetic material containing a two-dimensional surface crack was examined. The cause of the change in potential drop and the effects of the magnetic flux and the demagnetization on the change in potential drop were clarified by using the measuring systems with and without removing the magnetic flux from the circumference of the specimen. The change in potential drop was linearly decreased with increasing the tensile load and was caused by the change in conductivity near the crack tip. The reason of decreasing the change in potential drop with increasing the tensile load was that the increase of the conductivity near the crack tip due to the tensile load caused the decreases of the resistance and internal inductance of the specimen The relationship between the change in potential drop and the change in $K_I$ was not affected by demagnetization and was independent of the crack length.

• Composites Research
• /
• v.20 no.3
• /
• pp.17-24
• /
• 2007

In this study, the failure modes by ballistic impacts were studied both for a neat Kevlar woven fabric and a Kevlar liquid armor impregnated with shear thickening fluid (STF) containing silica particles. These two materials showed quite different failure modes macroscopically in ballistic impacts tests used by Cal.22 FSP and 9mm FMJ bullet. Yarn pull-out for the neat Kevlar woven fabric and yarn fracture occurred partially through all plies from 1st ply to last one for the STF-Kevlar are an important energy absorption mechanisms. The results observed by S.E.M showed commonly fiber damage which are torn skin in the longitudinal fiber direction, fiber split axially and fiber fracture for two materials. The reasons why STF-kevlar liquid armor material exhibits excellent ballistic performance are as follow: firstly the increased friction forces between yarn-yarn and fabric-fabric covered with silica particles and secondary the evolution of shear thickening phenomenmon resulting in suppression of yarn mobility.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.10a
• /
• pp.961-964
• /
• 2016

This paper describes the implementation of AUSV system for Sonar Image acquisition. The system be controlled by FF-PID algorithm for the thrusters using motion sensor and DGPS. As experimental results, the control performance is that the error distance from the destination positions are under 5m in total survey track of 1km, and the image deviation is under 12 pixel from the manned survey method, which the comparison with the total image quality is almost the same as the manned survey one. Thus the AUSV system is a new method of system can be utilized on the limited survey area as the surveyor should not be able to approach on sea surface.

• Geophysics and Geophysical Exploration
• /
• v.10 no.1
• /
• pp.1-18
• /
• 2007

Non-linear elastic wavefield inversion is a powerful method for estimating elastic parameters for physical constraints that determine subsurface rock and properties. Here, I introduce six elastic-wave velocity models by reconstructing elastic-wave velocity variations from real data and a 2D elastic-wave velocity model. Reflection seismic data information is often decoupled into short and long wavelength components. The local search method has difficulty in estimating the longer wavelength velocity if the starting model is far from the true model, and source frequencies are then changed from lower to higher bands (as in the 'frequency-cascade scheme') to estimate model elastic parameters. Elastic parameters are inverted at each inversion step ('simultaneous mode') with a starting model of linear P- and S-wave velocity trends with depth. Elastic parameters are also derived by inversion in three other modes - using a P- and S-wave velocity basis $('V_P\;V_S\;mode')$; P-impedance and Poisson's ratio basis $('I_P\;Poisson\;mode')$; and P- and S-impedance $('I_P\;I_S\;mode')$. Density values are updated at each elastic inversion step under three assumptions in each mode. By evaluating the accuracy of the inversion for each parameter set for elastic models, it can be concluded that there is no specific difference between the inversion results for the $V_P\;V_S$ mode and the $I_P$ Poisson mode. The same conclusion is expected for the $I_P\;I_S$ mode, too. This gives us a sound basis for full wavelength elastic wavefield inversion.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.8 no.6
• /
• pp.64-72
• /
• 2009

In this paper, a high efficiency 2.45 GHz rectenna with a microstrip patch antenna and a dual-mode band-pass filter in which the 2nd and 3rd harmonics are suppressed, is presented. From the experimental results, the 2.45GHz rectenna using 3rd harmonic suppressed dual-mode BPF shows the conversion efficiency of 41.6% with incident power density of 0.3 mW/cm2 and the received power of 1.66 mW. This result shows high conversion efficiency because the received power of this rectenna is lower than other rectennas to be compared with. This rectenna can be applied to the WPT (Wireless Power Transmission) field for energy harvesting. Also, it is expected to be used to provide the stand-by power for the low power devices for USN, and wireless power transfer in sensor application of MEMS devices.

• The Journal of the Acoustical Society of Korea
• /
• v.15 no.5
• /
• pp.99-106
• /
• 1996

The noise of a compressor is a major contributor to overall noise radiated from the refrigerator. The major source of the noise is radiated by the vibration of the compressor shell. In this study, to identify the dynamic characteristics of compressor shell, a compressor shell is divided into several components and these are analyzed with a commercial FEM(Finite Element Method) package such as MSC/NASTRAN. Using substructure synthesis method, the dynamic characteristics of the total system is identified. The coherence of each component to the total system is computed by using strain and kinetic energy. To increase the frequency of the first resonance mode which is most effective mode to the noise of the compressor shell, the improving strategy of dynamic characteristics is suggested by changing mass and stiffness of the coherence component to the first mode.

• Journal of IKEEE
• /
• v.23 no.1
• /
• pp.254-260
• /
• 2019

The failure rate of bidirectional dc-to-dc converter is predicted through the failure mode and effect analysis (FMEA) and the fault-tree analysis (FTA) considering the operational risk. In order to increase the driving voltage of the electric vehicle efficiently, the bidirectional converter is attached to the front of the inverter. It has a boost mode for discharging battery power to the dc-link capacitor and a buck mode for charging the regenerative power to the battery. Based on the results of the FMEA considering the operating characteristics of the bidirectional converter, the fault-tree is designed considering the risk of the converter. After setting the design parameters for the MCU for the electric vehicle, we analyze the failure rate of the capacitor due to the output voltage ripple and the inductor component failure rate due to the inductor current ripple. In addition, we obtain the failure rate of major parts according to operating temperature using MIL-HDBK-217F. Finally, the failure rate and the mean time between failures (MTBF) of the converter are predicted by reflecting the part failure rate to the basic event of the fault-tree.