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- 저자 : 유병관 ( Byung Kwan Yu ) (검색결과 4 건)
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Multirate 통신환경에서 DAMA 스케줄러를 이용한 슬라이스 채널 할당방법
유병관,김해기,안치훈,김남,김수형,Yu, Byung-Kwan,Kim, Hae-Ki,An, Chy-Hun,Kim, Nam,Kim, Soo-Hyung 한국전자파학회 1999 한국전자파학회논문지 Vol.10 No.2
본 논문에서는 이동 무선 시스템 설계시 중요한 채널 할당에 대한 TFS(Time-Frequency Slice)할당 방법 을 제시하였다. 시간-주파수-코드영역을 슬라이스화 하고 요구할당 다중접속(DAMA) 스케줄러를 이용하여 채널을 할당하는 경우 TA (Traditional Assignment) 방식에 비해서 호 차단 확률을 낮추게 된다. 통화량 부 하 $\rho$=0.8이고 요구되는 호 차단 확률이 2%일 때 TA (Traditional Assignment)방식에서는 사용자들에게 11 개의 슬라이스를 할당할 수 있지만. TFS방식에서는 36개의 슬라이스를 할당할 수 있다. 통화량 부하 $\rho$=0.9 일 때 TA방식에서 1%의 호 차단 확률을 기준으로 13개 이상의 슬라이스를 할당할 수 없지만, TFS(TimeF Frequency-Code sliced)방식에서는 40개의 슬라이스를 할당함으로써 TA방식보다 3.07배 향상되었다. 이러한 T TFS방식은 다중속도 사용자들이 많은 시스템구현에 적합한 방법이다. In this paper the new channel allocation method which is important in designing mobile radio system, is proposed. If the channel is allocated by time-frequency-code sliced and using DAMA scheduler, the blocking probability is lower than TA channel allocation method. With traffic load $\rho$=0.8 and 2% of blocking probability, TFS method can allocate 36 slices compared to 11 slices in TA method. At traffic load $\rho$=0.9 and 1% of blocking probability, the maximum available slices are 13 in TA method, but in TFS method 40 slices are allocated to user, so TFS method is better frequency availability by 3.75 times than TA method. TFS method could be suitable for system planning to multirate communication users.
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저온 원자층 증착으로 형성된 ZnO박막의 물성과 결정성 연구
유병관 ( Byung Kwan Yu ),한정조 ( Jeung Jo Han ),송오성 ( Oh Sung Song ) 대한금속·재료학회 2010 대한금속·재료학회지 Vol.48 No.12
ZnO thin films were deposited on Si(100) substrates at low temperatures (44℃~210℃) by atomic layer deposition using DEZn (diethyl zinc) and water as precursors. The film thickness was measured by ellipsometry calibrated with cross-sectional TEM. The phase formation, microstructure evolution, UV-absorbance, and chemical composition changes were examined by XRD, SEM, AFM, TEM, UV-VIS-NIR, and AES, respectively. A uniform amorphous ZnO layer was formed even at 44℃ while stable crystallized ZnO films were deposited above 90℃. All the samples showed uniform surface roughness below 3 nm. Fully crystallized ZnO layers with a band-gap of 3.37 eV without carbon impurities can be formed at substrate temperatures of less than 90℃.
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투명전도층이 없는 염료감응형 태양전지의 Ru 상대전극 연구
노윤영 ( Yun Young Noh ),유기천 ( Ki Cheon Yoo ),유병관 ( Byung Kwan Yu ),한정조 ( Jeung Jo Han ),고민재 ( Min Jae Ko ),송오성 ( Oh Sung Song ) 대한금속재료학회 ( 구 대한금속학회 ) 2012 대한금속·재료학회지 Vol.50 No.2
A TCO-less ruthenium (Ru) catalytic layer on glass substrate instead of conventional Ru/TCO/glass substrate was assessed as counter electrode (CE) material in dye sensitized solar cells (DSSCs) by examining the effect of the Ru thickness on the DSSC performance. Ru films with different thicknesses (34, 46, 69, and 90 nm) were deposited by atomic layer deposition (ALD) on glass substrates to replace both existing catalyst and electrode layer. In order to make our comparison, we also prepared an Ru catalytic layer by a similar method on FTO/glass substrate. Finally, we prepared the 0.45 cm2 DSSC device the properties of the DSSCs were examined by cyclic voltammetry (CV), impedance spectroscopy (EIS), and current-voltage (I-V) method. CV measurementsrevealed an increase in catalytic activity with increasing film thickness. The charge transfer resistance at the interface between the electrolyte and Rudecreased with increasing Ru thickness. I-V resultsshowed that the energy conversion efficiency increased up to 1.96%. Our results imply that TCO-less Ru/glass might perform as both catalyst and electrode layer when it is used in counter electrodes in DSSCs.
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저온 원자층증착법으로 제조된 ZnO/TiO2 나노이층박막의 물성 연구
노윤영 ( Yun Young Noh ),한정조 ( Jeung Jo Han ),유병관 ( Byung Kwan Yu ),송오성 ( Oh Sung Song ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.6
We examined the microstructure and optical properties of crystallized ~30 nm-ZnO/~10 nm amorphous TiO2 nano bilayered films as nano electrodes were deposited at extremely low substrate temperatures of 150-210℃. The bilayered films were deposited on silicon substrates with 10 cm diameters by ALD (atomic layer deposition) using DEZn (diethyl zinc(Zn(C2H5)2)) and TDMAT (tetrakis dimethyl-amid titanium(Ti(N(CH3)2)4) as the ZnO and TiO2 precursors, respectively, and H2O as the oxidant. The microstructure, phase, and optical properties of the bilayered films were examined by FE-SEM, TEM, XRD, AES, and UV-VIS-NIR spectroscopy. FE-SEM and TEM showed that all bilayered films were deposited very uniformly and showed crystallized ZnO and amorphous TiO2 layers. AES depth profiling showed that the ZnO and TiO2 films had a stoichiometric composition of 1:1 and 1:2, respectively. These bilayered films have optical absorption properties in a wide range of ultraviolet wavelengths, 250-390 nm, whereas the single ZnO and TiO2 films showed an absorption range of 350-380nm.
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