통합 검색 | Korea Science

Yu, G.;Li, J.G.;Lu, X.N.;Chang, X.Y.
- 한국추진공학회:학술대회논문집
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- 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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- pp.79-84
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- 2004
This paper report our preliminary results of characterizing the jet structures of kerosene injection into quiescent atmosphere and a Mach 2.5 crossflow at various preheat temperature. A heating system has been designed and tested that can prepare heated kerosene of 0.8 kg up to 670 K at a pressure of 5.5 ㎫. Temperature measurement near the injector shows that the temperature of pressurized kerosene can be kept constant during the experimental duration. Comparison of kerosene jet structures in the preheat temperature range of 290-550 K demonstrates that with injection pressure of 4 ㎫ the jet plume turns into vapor phase completely at injection temperature of 550 K, while keeping the penetration depth essentially unchanged. The results suggest that the injection of vaporized fuel would improve the performance of a liquid hydrocarbon-fueled supersonic combustor because the evaporation process is now omitted.
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Zhao, Wusheng;Zhong, Kun;Chen, Weizhong;Xie, Peiyao
- Earthquakes and Structures
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- 제22권6호
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- pp.549-559
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- 2022
The quasi-static finite element (FE) approaches are widely used for the seismic analysis of tunnels. However, the conventional quasi-static approaches may cause significant deviations when the tunnel excavation process is simulated prior to the quasi-static analysis. In addition, they cannot account for vertical excitations. Therefore, this paper first highlights the limitations of conventional approaches. A hybrid quasi-static FE approach is subsequently proposed and extensively validated for various conditions. The hybrid approach is simple and not time consuming, and it can be used for the preliminary seismic design of tunnels, especially when the tunnel excavation and vertically propagating P-waves are considered.
https://doi.org/10.12989/eas.2022.22.6.549 인용 KSCI

김영재;유영석;심원철;박창성;정재우;오용수
- 대한전기학회:학술대회논문집
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- 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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- pp.1621-1622
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- 2006
This paper presents the effect of driving waveform for piezoelectric bend mode inkjet printhead with optimized mechanical design. Experimental and theoretical studies on the applied driving waveform versus jetting characteristic s were performed. The inkjet head has been designed to maximize the droplet velocity, minimize voltage response of the actuator and optimize the firing frequency to eject ink droplet. The head design was carried out by using mechanical simulation. The printhead has been fabricated with Si(100) and SOI wafers by MEMS process and silicon direct bonding method. To investigate how performance of the piezoelectric ceramic actuator influences on droplet diameter and droplet velocity, the method of stroboscopy was used. Also we observed the movement characteristics of PZT actuator with LDV(Laser Doppler Vibrometer) system, oscilloscope and dynamic signal analyzer. Missing nozzles caused by bubbles in chamber were monitored by their resonance frequency. Using the water based ink of viscosity of 4.8 cps and surface tension of 0.025N/m, it is possible to eject stable droplets up to 20kHz, 4.4m/s and above 8pL at the different applied driving waveforms.
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