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Modeling and Verification of a Contactless Air Film Conveyor Using a Viscous Traction Principle
Wei Zhong,Xiaoyu Gu,Ke Xu,Fanghua Liu,Xin Li,Toshiharu Kagawa 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.12
Many industries require contactless transport of delicate or clean products such as silicon wafers, flat foodstuffs and freshly painted objects. In this study, a contactless air film conveyor for flat objects is introduced. The object is supported by a thin film formed between the object and the conveyor surface and transported by viscous traction which is generated by controlled airflow underneath the object. Experiments are conducted to investigate the film pressure distribution and viscous force. The results show that the film pressure is symmetrically distributed along the direction perpendicular to the airflow in the actuating cells and non-symmetrically distributed along the airflow direction. The viscous force decreases as the increase of gap thickness. A simplified model is established to help understand and characterize the viscous force. The calculated results show a good agreement with the experimental data. It is revealed that the viscous force is the resultant of an actuating force in the pocket and side areas and a drag force from airflow across the dam area. Simulation and experiments are conducted using a PID controller for one dimension position control and position tracking. The results verify the effectiveness of the theoretical modeling and control method.
A lateral superjunction SOI LDMOS with double‑conductive channels
Weizhong Chen,Haifeng Qin,Xuwei Lin,Yi Huang,Zhengsheng Han 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.4
A novel lateral superjunction silicon-on-insulator lateral double-diffused MOS with double-conductive channels (DCLDMOS) is proposed and subsequently investigated by the SENTAURUS TCAD. First, the double channels (DC) feature a surface and bulk gate for providing the surface and bulk electron channels, respectively. Second, the P-pillar is inserted into the N-drift to divide it into the N-drift1 and N-drift2 regions. In this manner, the lateral super junction (SJ) can be formed by the sandwich-structured N-drift1/P-pillar/N-drift2. At the forward conduction state, the DC provides the double electron emission channels. The specific on-resistance (Ron,sp) is obviously decreased, and an even higher peak transfer conductance (gm) is achieved. At the breakdown state, the SJ helps to deplete the whole drift, including the N-drift1/P-pillar/N-drift2, and the electric field Efield distribution is effectively optimized. Furthermore, the Ron,sp is significantly decreased by the DC and SJ. Consequently, the tradeoff relationship between BV and Ron,sp is improved by the charge compensation and the assisted depletion effect, which are performed by the SJ. The results indicate that the DC LDMOS can break through the single RESURF and achieve Baliga’s figure of merit (FOM) of 3.32 MW/cm2. In addition, the DC LDMOS with the N-trench (NT) inserted into the buried oxide (DC-NT LDMOS) can achieve better breakdown properties by further optimizing the Efield distribution between the source and drain regions, and BV is remarkably increased. Furthermore, Ron,sp can be decreased by the NT. Finally, it breaks through the triple RESURF to achieve the FOM of 4.87 MW/cm2.
A snapback‑free reverse‑conducting IGBT with multiple extraction channels
Weizhong Chen,Xuwei Lin,Shun Li,Yao Huang,Yi Huang,Zhengsheng Han 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.2
A novel Reverse-Conducting Insulated Gate Bipolar Transistor (RC-IGBT) with Multiple Extraction Channels (MEC) is proposed and investigated. The MEC is characterized by two transistors NPN1 (Nbuffer/Pbarrier/Ncollector), NPN2 (Nbuffer/Pfloat/Npoly) and short Rgap in the collector. The P-Collector, N-Collector, polysilicon and Rgap are shorted together, thus the NPN1, NPN2 and Rgap are parallel with the PNP transistor (Pbody/Nbuffer/Pcollector). At the forward conduction, the unipolar mode is effectively suppressed by the electron barriers P-barrier (the base of the NPN1) and P-float (the base of the NPN2), thus the snapback effect can be completely eliminated. At the turn-off, the electrons are quickly extracted by three channels of the NPN1, NPN2 and Rgap, thus the Eoff can be remarkably decreased. Results show at the same Von of 2.8 V, the Eoff of the MEC RC-IGBT is reduced by 20%, 37%, 45% and 59% compared to AB, FPL, DFS and TOC RC-IGBT, respectively. Therefore the excellent trade-off characteristics with snapback free are achieved.
Realistic Scenes Reproduction Based on Total Variation
( Weizhong Li ),( Honghua Ma ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.11
In order to completely record all the information of realistic scenes, high dynamic range (HDR) images have been widely used in virtual reality, photography and computer graphics. A simple yet effective tone mapping method based on total variation is proposed so as to reproduce realistic scenes on low dynamic range (LDR) display devices. The structural component and texture component are obtained using total variation model in logarithmic domain. Then, the dynamic range of the structural component is compressed with an adaptive arcsine function. The texture component is processed by Taylor series. Finally, we adjust the saturation component using sigmoid function and restore the color information. Experimental results demonstrate that our method outperforms existing methods in terms of quality and speed.
A Tone Mapping Algorithm Based on Multi-scale Decomposition
( Weizhong Li ),( Benshun Yi ),( Taiqi Huang ),( Weiqing Yao ),( Hong Peng ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.4
High dynamic range (HDR) images can present the perfect real scene and rich color information. A commonly encountered problem in practical applications is how to well visualize HDR images on standard display devices. In this paper, we propose a multi-scale decomposition method using guided filtering for HDR image tone mapping. In our algorithm, HDR images are directly decomposed into three layers:base layer, coarse scale detail layer and fine detail layer. We propose an effective function to compress the base layer and the coarse scale detail layer. An adaptive function is also proposed for detail adjustment. Experimental results show that the proposed algorithm effectively accomplishes dynamic range compression and maintains good global contrast as well as local contrast. It also presents more image details and keeps high color saturation.
애니메이션에서 사운드에 의한 캐릭터화(Characterization)에 관한 연구
SU WEIZHONG,이상윤 한국음악교육공학회 2022 음악교육공학 Vol.- No.50
본 연구는 애니메이션에서 캐릭터의 특성과 성격의 형성을 위하여 사운드에 의한 캐릭터화의 새로운 가능성을 탐구하였다. 이러한 연구목적을 위하여 픽사 애니메이션 스튜디오의 단편 애니메이션 ‘Lou’의 캐릭터 음향 분석을 통하여 애니메이션 사운드의 새로운 기능과 역할을 고찰하였다. ‘Lou’의 주인공 캐릭터 Lou에 부여된 음향효과는 캐릭터의 정서 및 활동을 표현하였는데, 특히 정서를 표현하는 음향효과는 소리에 의한 캐릭터화에 중요한 역할을 하였다. 원래 보이지 않는 존재를 있는 것처럼 보여주는 Lou의 허상적 표현, 이 작품의 스토리에서 또 다른 주인공 캐릭터인 J.J.의 관점에서 Lou가 어떠한 환상으로 표현되는 점, 그리고 Lou가 실존하는 것이 사실인지의 여부가 불분명하기 때문에 그가 가상적인 캐릭터화가 되는 점은 이 작품에 나타난 사운드에 의한 캐릭터화의 새로운 가능성들로 해석되었다. 또한 이 작품에 구체적인 내용을 의미하는 대사가 거의 없는 가운데, Lou의 음향효과는 그의 대사 음성과 같은 역할을 수행하여 음향효과의 외연화를 실현한다. 그리고 이 작품에 나타난 Lou의 음향효과는 보이는 음향과 아쿠스메트르가 양립하는 해석을 가능하게 하여 음향에 의한 복합성을 나타낸다. 이와 같이 본 연구에서 애니메이션 캐릭터의 음향효과는 대사와 같은 역할을 수행하고, 허상, 환상, 가상, 외연, 아쿠스메트르 등을 복합적으로 표현함으로서 새로운 방법으로 사운드에 의한 캐릭터화를 실현하였다. 그러므로 본 연구의 결과는 보다 새로운 관점으로 애니메이션 캐릭터를 창조하는데 있어서 음향의 역할과 기능이 더 확대될 수 있는 가능성을 열어주었다.