• Journal of the Korean Vacuum Society
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• v.5 no.2
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• pp.119-126
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• 1996

The effect of the $O_2$ concentration in the sputtering gas mixture, substate temperature and Ar pressure on the structural and optical properties of 3 mol% YSZ and 8 mol% YSZ thin films deposited by RF magnetron sputtering were investigated . The films were observed to have various crystal structures with different compositions in accordance with the type of the target materials. The size of fine grain-like particles decreased wiht increasing the $O_2$ concentration in the sputtering gas in the case of 3mol% YSZ, while it increased in the case of 8 mol% YSZ . However, the average opticla transmission of 8mol% YSZ, despite of thicker thickness. was higher than that of 3 mol% YSZ. Furthermore, the values of refractive index of 3mol% YSZ increased with increasing the $O_2$ concentration in the sputtering gas on the contrary to those of the 8 mol% YSZ. However, the transmission spectra of 8 mol% YSZ films were not strongly influenced by the substrate temperature and Ar pressure, whereas the refractive index of the YSZ films were strongly affected by the sputtering parameters.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.94-97
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• 1989

It is shown that fundamental plasma characteristic, which are sheath voltage and ion concentration, can be derived from measuring RF impedence. Plasma characteristics from this simple method are verified by direct measuring, to be reasonable. Using these values a new relation between isotropy and the ratio of sheath voltage to ion concentration is derived. For etch in which $CF_4$ is used, anisotropic etch can be achieved in its order $10^{-12}Vcm^3$ and isotropic etch in $10^{-12}Vcm^3$. These results are useful in every asymetric diode type etch system.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1514-1515
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• 1998

Diamond thin films were deposited on n-type (100) Si wafers from $H_2-CH_4$ gas mixture by rf PACVD. Prior to deposition, mechanical scratching was done to improve density of nucleation sites with diamond paste of 3${\mu}m$. The microstructure of deposited diamond thin films was studied by using the following conditions : discharge power of 500W, $H_2$ flow rate of 50sccm, reaction pressure of 20torr, and $CH_4/H_2$ ratio of 0.3$\sim$1%. The deposited diamond thin films showed that the crystallite was increased at the lower methane concentration. The deposited thin films were characterized by Scanning Electron Microscopy. Raman Spectroscopy and Fourier-Transform Infrared Spectroscopy.

• Proceedings of the KIEE Conference
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• 2003.07e
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• pp.31-33
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• 2003

Power amplifier linearity plays a major role in the design of RF communication systems. In this paper, predistortion type linearizer was designed an independently controllable AM/AM and AM/PM predistortion linearizers. This linearizer allows independent adjustment of the AM/AM and AM/PM curves by using two adjustable voltages to compensate the power amplifier non-linearities. The predistortion linearizer was improved the ACPR by 6dB with cdma2000 multi carrier signals. Applying this linearizer to two-tone 880MHz power amplifier, an improvement of adjacent channel leakage power up to 5dBm has been achieved.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.7
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• pp.463-468
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• 2017

Eight types of LED packages were manufactured according to the type and composition ratio of phosphors by using commercially available white LED phosphors. CRI (Ra), a conventional color quality evaluation method was evaluated by using manufactured white LED; the Rf, Rg, color vector graphic, and color distortion graphic were evaluated with a new method, IES TM-30-15. The results of the evaluation confirmed that the new method compensated for the disadvantages of CRI, which was found to be inadequate when the color was saturated. The added evaluation index identified the chroma variation and color change. Furthermore, the study showed that the changes of Rf and Rg are small when controlling phosphors based on CRI, questioningthe necessity of identifyingchroma variation and color change.

• ETRI Journal
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• v.13 no.2
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• pp.21-27
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• 1991

Effects of annealing on the dielectric properties and microstructures of thin tantalum oxide film(25nm) deposited on p-type Si substrate with rf reactive magnetron sputtering were investigated. The leakage current density was remarkably reduced from $10^-8$ to $10^-12$ A/$\mum^2$at the electric field of 2MV/cm after rapid thermal annealing(RTA) in $O_2$at $1000^{\circ}C$, while little leakage reduction was observed after furnace annealing in $O_2$ at $500^{\circ}C$. The structural changes of thin tantalum oxide film after annealing were examined using high resolution electron microscope(HREM). The results of HREM show that substantial reduction in the leakage current density after the RTA in $O_2$ can be attributed to crystallization and reoxidation of the thin amorphous tantalum oxide film.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.04a
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• pp.69-72
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• 2000

기판과의 동시소성에 의한 고주파 MCM-C(Multi-Chip-Module-Cofired)용 저항을 제작하고 6 GHz 까지의 RF 특성을 측정하였다. 기판은 저온 소성용 기판으로서 총 8층으로 구성하였으며, 7층에 저항체 및 전극을 인쇄하고 Via를 통하여 기판의 최상부까지 연결되도록 하였다 저항체 Pastes, 저항체의 크기, Via의 길이 변화에 따라서 저항의 RF 특성은 고주파일수록 더욱 DC 저항값에서부터 변화되는 양상을 보였다. 내부저항의 등가회로를 구현한 결과, 저항은 전송선로, Capacitance 성분이 혼재되어 있는 것으로 나타났으며 전극의 형태에 따라 Capacitance 성분이 많은 차이를 나타내었다.

• Journal of electromagnetic engineering and science
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• v.1 no.2
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• pp.166-172
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• 2001

A novel RF tunable bandpass filter structure using dielectric resonators and varactor diodes is considered for the optimization to achieve constant bandwidth with minimum passband insertion loss. The coupling between resonators is realized by coupling windows and series lumped L, C elements are used to realize the input/output stage couplings. A 5 poles, 0.01 dB ripple Chebyshev type filter tuned from 800 MHz~900 MHz is designed and presented in this paper. The passband bandwidth for the design is 10 MHz (fractional bandwidth = 1.2 %). Experimental results show that the 3 dB passband bandwidth variation is 12.04 MHz~12.16 MHz (less than 1 %) and passband insertion loss is 15 dB~7 dB depending on the tuning voltages.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.153-155
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• 2006

An automatic remote water measurement system was developed. This system sends automatic remote measured and collected water meters data automatically from the transmitter with CDMA modem through SK-Telecom network The water meter data are received through LAH TCP/IP and displayed as test file on IE(Internet Explorer) window. The existing water meters of mechanical type have so many problems to measure data. The person must visit the location of each water meters and write down the data records manually. In this system the RF module has attached each water meter Client/Server programs are developed by network socket programming.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.247-249
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• 2004

Electric systems can be classified into two classes on the basis of the location of its energy source. One system is to be connected with its outside energy source. Obviously, these electric system is limited of its motion range and impossible to operate in the situation without a way to find an energy source nearby. another is to posses the energy source within it. These electric systems are free of motion range limit while their using is limited by the life of source. These limits can be tided over by using passive-type RF communication. RF-ID is a system that Is possible to interchange electricity and data by Radio Frequency to locate and identify various objects including a man.