http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
이봉희(Bonghee Lee),전보현(Bohyeon Jeon),강상모(Sangmo Kang) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Research about butterfly valve's flow characteristics had been achieved about pressure loss factor of valve, cavitation, torque characteristics, flux control characteristics and valve performance etc. mainly. LNG must equip durability with enough intensity having intention because transport and stored in ultra low temperature state of - 162℃. Specially, when work migration, efficiency of valve and highly stability are required. But, an experiment is impossible effectively to problem of huge expense to embody a engineering experiment about cryogenic fluid flow. Therefore, achieved CFD analysis that allow to Reynolds averaged Navier- Stokes equation. It used commercial code CFX11.0 to achieve study hydromechanics about triple eccentric butterfly valve's flow characteristic and other physical design argument. At first, produced flow coefficient by CFD that apply water by working fluid. Because comparing it with typical value, verified validity. And that achieve analysis for cryogenic. state. Eddy flow and pressure change that develop to valve disk rear of various turbulence model in this study applied predictable k-w SST(Shear-Stress Transport) model comparatively
Choi Byoungdeog,Choi Pyungho,Kim Soonkon,Jeon Bohyeon,Lee Jongyoon,Jungmin Park 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.2
This study investigates the eff ect of the gate SiO 2 thickness (80, 100, and 130 nm) deposited by plasma enhanced chemical vapor deposition on the interface and reliability characteristics of low-temperature polycrystalline silicon thin fi lm transistors. Field eff ect mobility is signifi cantly degraded as the gate oxide thickness decreases. The border trap density (N bt ) extracted from capacitance–voltage hysteresis exhibits no trend with respect to the gate oxide thickness, indicating that fi eld eff ect mobility is not governed by N bt . The quantitative interface trap density (N it ) was obtained using a 3-terminal charge pumping method; results showed that N it decreased as the gate oxide thickness increased. However, it was observed that the threshold voltage (V th ) shift during negative bias temperature stress is worse in the thicker SiO 2 fi lm, which has a low N it . After activation annealing, the amount of hydrogen in the gate oxide increased as the thickness of the insulator was raised. This in turn caused a larger shift in V th . To validate this mechanism, the amount of hydrogen with respect to the device depth was analyzed via secondary ion mass spectroscopy. It has been found that the presence of more hydrogen concentration in the SiO 2 fi lm and the interface to the thicker SiO 2 results in more V th shifts under bias temperature stress.
Jungmin Park,Hyojung Kim,Pyungho Choi,Bohyeon Jeon,Jongyoon Lee,Changyong Oh,Bosung Kim,Byoungdeog Choi 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.4
This study investigated the electrical and stability characteristics of Al 2 O 3 as a gate insulator, which was deposited by variousatomic layer deposition methods in top-gate staggered amorphous InGaZnO (a-IGZO) thin fi lm transistors. A trimethylaluminumprecursor was used as an Al source, and H 2 O gas (H 2 O device) and O 2 plasma with a long plasma time (O 2 LP device)and a short plasma time (O 2 SP device) were used as oxidants. The initial electrical characteristics, including the hysteresis,on–off current ratio, and subthreshold swing, were superior in the H 2 O device compared to the O 2 LP and O 2 SP devices. Inthe positive bias stress (PBS) results, the degradation characteristics showed a tendency similar to the transfer properties. However, under the negative bias illumination stress (NBIS), the stability of the H 2 O device was signifi cantly reduced comparedto the O 2 LP and O 2 SP devices. In this paper, the mechanism of instability, which has opposite results in terms of thePBS and NBIS for the three devices, was identifi ed using capacitance–voltage, three-terminal charge pumping as electricalanalysis techniques and secondary ion mass spectroscopy (SIMS) as a physical analysis technique. It was confi rmed thatthe surface oxidation of a-IGZO deteriorates the interfacial properties, causing the transfer characteristics to degrade. Thecarbon of the Al 2 O 3 fi lm identifi ed via SIMS analysis acts as a trap layer, causing deterioration in the PBS. Alternatively, inthe NBIS, it was observed that the carbon acts as a capture site for photo-excited holes, thereby promoting device stability.