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Effects of some factors on the thermal-dissipation characteristics of high-power LED packages
Peng Fei Ji,문철희 한국정보디스플레이학회 2012 Journal of information display Vol.13 No.1
Decreasing the thermal resistance is the critical issue for high-brightness light-emitting diodes. In this paper, the effects of some design factors, such as chip size (24 and 35 mil), substrate material (AlN and high-temperature co-fired ceramic), and dieattach material (Ag epoxy and PbSn solder), on the thermal-dissipation characteristics were investigated. Using the thermal transient method, the temperature sensitivity parameter, Rth (thermal resistance), and junction temperature were estimated. The 35-mil chip showed better thermal dissipation, leading to lower thermal resistance and lower junction temperature, owing to its smaller heat source density compared with that of the 24-mil chip. By adopting an AlN substrate and a PbSn solder,which have higher thermal conductivity, the thermal resistance of the 24-mil chip can be decreased and can be made the same as that of the 35-mil chip.
Ji-Peng Dong,Jing-Guang Sun,Yong Guo,Shen-Min Song 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.4
In order to meet the needs of high-precision guidance for missile-guided maneuvering targets in the presence of towed bait interference, this paper proposes a new guidance strategy based on heading angle method and parallel approaching method. Its main idea: a suitable angle is determined by heading angle method which of the missile trajectory is above that of the towing bait. Meanwhile, the accurate interception of missiles to targets is guaranteed by parallel approaching method. Firstly, system models of missile and target with towed decoy are established. Then, considering unknown bounded system disturbances, a controller is given based on sliding mode, back-stepping method. Furthermore, to solve the input saturation problem, an anti-saturation controller is given using adaptive and back-stepping sliding mode methods. Finally, strict proofs of the two controllers are given using Lyapunov stability theory, and simulations are carried out to verify the effectiveness of the two controllers.
De novo malignancy after liver transplantation
Peng Ji Gao,Jie Gao,Zhao Li,Zhi Ping Hu,Ji Ye Zhu 대한외과학회 2015 Annals of Surgical Treatment and Research(ASRT) Vol.88 No.4
Purpose: The aim of this study is to evaluate the incidence of de novo malignancy after liver transplantation (LT) and compare with those among the general Chinese population. Methods: A total of 466 patients who had a minimum follow-up time of 6 months were enrolled in the study. All data of medical records and follow up were retrospectively reviewed. Results: The incidence rate of de novo malignancy was 3.0% (14 in 466 patients). The median elapsed time from transplant to the diagnosis of de novo malignancy was 42 months (range, 6 to 106 months). The cumulative risk for development of de novo malignancy was 1.6%, 2.7%, and 8.2% at 3, 5 and 10 years after LT, respectively. The patients were all male. The types of de novo tumors included digestive system tumor (8 in 14), lung cancer (2 in 14), urologic neoplasm (2 in 14), and hematologic malignant tumor (2 in 14). Over a mean follow-up of 24 months after diagnosis of de novo malignancy, 7 patients (50.0%) died; the overall 5-year patient survival rate was 54.5%. The relative risk of malignancy following LT was 9.5 folds higher than the general Chinese population. Conclusion: The relative risk of malignancy following LT was much higher than the general Chinese population. Digestive system tumor is the most common type of de novo malignancy after LT in China.
Effects of some factors on the thermal-dissipation characteristics of high-power LED packages
Ji, Peng Fei,Moon, Cheol-Hee The Korean Infomation Display Society 2012 Journal of information display Vol.13 No.1
Decreasing the thermal resistance is the critical issue for high-brightness light-emitting diodes. In this paper, the effects of some design factors, such as chip size (24 and 35 mil), substrate material (AlN and high-temperature co-fired ceramic), and die-attach material (Ag epoxy and PbSn solder), on the thermal-dissipation characteristics were investigated. Using the thermal transient method, the temperature sensitivity parameter, $R_{th}$ (thermal resistance), and junction temperature were estimated. The 35-mil chip showed better thermal dissipation, leading to lower thermal resistance and lower junction temperature, owing to its smaller heat source density compared with that of the 24-mil chip. By adopting an AlN substrate and a PbSn solder, which have higher thermal conductivity, the thermal resistance of the 24-mil chip can be decreased and can be made the same as that of the 35-mil chip.
Microstructure of Antarctic Krill (Euphausia suberba) Cuticle
Yuanhuai Peng,Wei Ji,Hongwu Ji 한국해양과학기술원 2022 Ocean science journal Vol.57 No.2
In this study, the microstructure of Antarctic krill cuticle was deeply investigated using scanning electron microscope (SEM). The krill cuticles were treated with clean water, dilute hydrochloric acid solution and dilute sodium hydroxide solution to remove the adhesive substances, inorganic salts and protein, respectively. The organic substances were removed by sintering the cuticle in a muffle furnace to obtain the inorganic salts. The resulting cuticle of Antarctic krill was then observed under SEM and it was found that the cuticle has a hierarchical structure in which the α-crystal chitin fibers, with chitin spheres, extended from the pore canals, thus shaping layers; multiple stacked layers formed the three-dimensional structure; the inorganic salts were sparsely distributed in the cuticle; protein was wrapped around the surfaces of the chitin fiber bundles and the crystals of inorganic salts. These structural investigations revealed the interrelation among the main components of Antarctic krill cuticle. This study and following studies will be helpful in understanding the relationship between the forms of fluorine in Antarctic krill cuticle and its structural changes during postmortem storage.
Ji, Do-Hyeon,Kim, Byong-Wan,Sargolzehi, Mohammad Mahdi,Kang, Shin-Gon,Lee, Bae-Hun,Peng, Jing-Lun,Nejad, Jalil Ghassemi,Min, Doo-Hong,Sung, Kyung-Il The Korean Society of Grassland and Forage Science 2014 한국초지조사료학회지 Vol.34 No.3
The objective of this study was to determine the best performing switchgrass (Panicumvirgatum L.) cultivar with three different seeding dates as a bioenergy source in Republic of Korea. Split-plot in time with three replications was performed and three switchgrass cultivars, Carthage (CT), Cave-in-Rock (CIR), and Forestburg (FB) were used in this experiment from 2009 to 2012. Plots were seeded on April 23, May 4, and May 13, 2009 and were harvested once in November each year. No fertilizer was applied to the field for the first year; however, in second and third years (June 2010 and May 2011, respectively), N, $P_2O_5$ and K2O fertilizers were applied in 67,45 and 90 kg $ha^{-1}$, respectively. Soil pH (5.9) and climate condition including temperature ($10.4{\sim}17.5^{\circ}C$) and precipitation (89.4~109.8 mm $month^{-1}$) were suitable for switchgrass cultivation. Total dry matter yields were higher in CT and CIR compared to FB and were 16.9, 15.9, and 4.5 ton $ha^{-1}$, for CT, CIR, and FB, respectively (p<0.0001). The samples were analyzed for dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), crude fiber (CF), ether extract (EE), and ash. No significant differences in energy content (p = 0.96) and chemical composition among cultivars (p>0.05) were found. Seeding dates did not affect DM yield (ton $ha^{-1}$), chemical composition and energy content significantly (p>0.05). Significant difference was observed for heights among CT, CIR, and FB (177.59, 169.98, and 94.89 cm, respectively, p = 0.0002). In conclusion, based on soil characteristics and climate condition in Korea compared to other countries, switchgrass can be cultivated successfully. Considering dry matter yield and energy content of these three cultivars of switchgrass CT and CIR adapted better to climate in Middle Eastern of Republic of Korea than Forestburg for bioenergy purpose.
ESVD: An Integrated Energy Scalable Framework for Low-Power Video Decoding Systems
Ji, Wen,Chen, Min,Ge, Xiaohu,Li, Peng,Chen, Yiqiang Hindawi Publishing Corporation 2010 Eurasip Journal on Wireless Communications and Net Vol.2010 No.-
<P>Video applications using mobile wireless devices are a challenging task due to the limited capacity of batteries. The higher complex functionality of video decoding needs high resource requirements. Thus, power efficient control has become more critical design with devices integrating complex video processing techniques. Previous works on power efficient control in video decoding systems often aim at the low complexity design and not explicitly consider the scalable impact of subfunctions in decoding process, and seldom consider the relationship with the features of compressed video date. This paper is dedicated to developing an energy-scalable video decoding (ESVD) strategy for energy-limited mobile terminals. First, ESVE can dynamically adapt the variable energy resources due to the device aware technique. Second, ESVD combines the decoder control with decoded data, through classifying the data into different partition profiles according to its characteristics. Third, it introduces utility theoretical analysis during the resource allocation process, so as to maximize the resource utilization. Finally, it adapts the energy resource as different energy budget and generates the scalable video decoding output under energy-limited systems. Experimental results demonstrate the efficiency of the proposed approach.</P>