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Shaohua Wu 한국콘텐츠학회 2011 ICCC International Digital Design Invitation Exhib Vol.2011 No.5

SiC IGBT degradation mechanism investigation under HV‑H3TRB tests

Ziming Wu,Zongbei Dai,Jian Zhou,Huafeng Dong,Wencan Wang,Feiwan Xie,Haoran Wang,Jiahui Yan,Xiyu Chen,Shaohua Yang,Fugen Wu 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.2

The high voltage-high humidity-high temperature reverse bias (HV-H3TRB) test was utilized to evaluate the reliability of silicon carbide insulated gate bipolar transistors (SiC IGBTs). Moisture invasion often induces termination/passivation and metal corrosion. Therefore, the HV-H3TRB test is generally used to assess termination / passivation robustness. However, under the HV-H3TRB test conditions, gate quality degradation may occur. In this study, the dominant degradation mechanism of SiC IGBTs was investigated. The changes of the most sensitive static characteristics (e.g., threshold voltage, breakdown voltage, and leakage current) were recorded. The threshold voltage decreased and leakage current increased substantially after > 1000 h of HV-H3TRB tests under 85 ℃/85% RH climate conditions. Capacitance-voltage (C-V) curve measurements indicated that the mobile ions at the SiC/SiO2 interface or in the gate oxide likely caused the threshold-voltage instability in the SiC IGBTs after the HV-H3TRB tests. This instability can be recovered by applying a negative gate bias. Subsequent failure analysis confirmed no corrosion of metals or termination/passivation in the device, which indicates the robustness of the passivation (consisting of phosphor-silicate glass and Si3N4). Therefore, the gate quality appears to be a significant reliability risk for SiC IGBTs under high humidity, high temperature, and high voltage conditions.

Purification and Characterization of an Antioxidant Protein from Fertilized Eggs

Shaohua Yang,Zhengjiang Tang,ShanShan Tang,Tingfang Zhang,Fei Tang,Yu Wu,Ying Wang,Lulu Wang,Guoqing Liu 한국축산식품학회 2016 한국축산식품학회지 Vol.36 No.6

Free radicals may attack cells or tissue, leading to chronic diseases, and antioxidant consumption is potentially useful for removing free radicals. Egg proteins may be used as potential sources of antioxidant considering their ability of scavenging free radicals to apply for food or cosmetics industry. In this study, we obtained a natural antioxidant protein from fertilized eggs, which was a dietary supplement in some Asian countries. Meanwhile, antioxidant activities of these proteins were evaluated using different oxidation systems. With increasing incubation time, the antioxidant activity of these proteins increased during 15 d of incubation. The samples on day 15 were performed for isolation of antioxidant protein. The protein, named P4-1 (MW, 45 kDa), was isolated and purified by consecutive chromatographic methods. P4-1 contained 17 amino acids, which was determined by liquid chromatography-mass spectrometry and Amino Acid Analyzer. Moreover, the amino acid sequence was highly similar to that of ovalbumin. Differential scanning calorimetry showed that the denaturation temperature of P4-1 was 57.16ºC. Furthermore, P4-1 suggested high oxygen radical-absorbance activity in ·OH assays, and its antioxidant activity was stable at 30-50ºC in acidic and neutral pH. Thus, these results revealed that P4-1 may be a potential resource as a natural antioxidant.

Purification and Characterization of an Antioxidant Protein from Fertilized Eggs

Yang, Shaohua,Tang, Zhengjiang,Tang, ShanShan,Zhang, Tingfang,Tang, Fei,Wu, Yu,Wang, Ying,Wang, Lu Lu,Liu, Guoqing Korean Society for Food Science of Animal Resource 2016 한국축산식품학회지 Vol.36 No.6

Free radicals may attack cells or tissue, leading to chronic diseases, and antioxidant consumption is potentially useful for removing free radicals. Egg proteins may be used as potential sources of antioxidant considering their ability of scavenging free radicals to apply for food or cosmetics industry. In this study, we obtained a natural antioxidant protein from fertilized eggs, which was a dietary supplement in some Asian countries. Meanwhile, antioxidant activities of these proteins were evaluated using different oxidation systems. With increasing incubation time, the antioxidant activity of these proteins increased during 15 d of incubation. The samples on day 15 were performed for isolation of antioxidant protein. The protein, named P4-1 (MW, 45 kDa), was isolated and purified by consecutive chromatographic methods. P4-1 contained 17 amino acids, which was determined by liquid chromatography-mass spectrometry and Amino Acid Analyzer. Moreover, the amino acid sequence was highly similar to that of ovalbumin. Differential scanning calorimetry showed that the denaturation temperature of P4-1 was $57.16^{\circ}C$. Furthermore, P4-1 suggested high oxygen radical-absorbance activity in ${\cdot}OH$ assays, and its antioxidant activity was stable at $30-50^{\circ}C$ in acidic and neutral pH. Thus, these results revealed that P4-1 may be a potential resource as a natural antioxidant.

Radio Resource Management of CoMP System in HetNet under Power and Backhaul Constraints

( Jia Yu ),( Shaohua Wu ),( Xiaodong Lin ),( Qinyu Zhang ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.11

Recently, Heterogeneous Network (HetNet) with Coordinated Multi-Point (CoMP) scheme is introduced into Long Term Evolution-Advanced (LTE-A) systems to improve digital services for User Equipments (UEs), especially for cell-edge UEs. However, Radio Resource Management (RRM), including Resource Block (RB) scheduling and Power Allocation (PA), in this scenario becomes challenging, due to the intercell cooperation. In this paper, we investigate the RRM problem for downlink transmission of HetNet system with Joint Processing (JP) CoMP (both joint transmission and dynamic cell selection schemes), aiming at maximizing weighted sum data rate under the constraints of both transmission power and backhaul capacity. First, joint RB scheduling and PA problem is formulated as a constrained Mixed Integer Programming (MIP) which is NP-hard. To simplify the formulation problem, we decompose it into two problems of RB scheduling and PA. For RB scheduling, we propose an algorithm with less computational complexity to achieve a suboptimal solution. Then, according to the obtained scheduling results, we present an iterative Karush-Kuhn- Tucker (KKT) method to solve the PA problem. Extensive simulations are conducted to verify the effectiveness and efficiency of the proposed algorithms. Two kinds of JP CoMP schemes are compared with a non-CoMP greedy scheme (max capacity scheme). Simulation results prove that the CoMP schemes with the proposed RRM algorithms dramatically enhance data rate of cell-edge UEs, thereby improving UEs` fairness of data rate. Also, it is shown that the proposed PA algorithms can decrease power consumption of transmission antennas without loss of transmission performance.

Industrial test on coal re-burning at a 600MW utility boiler and NOx reduction

Penghua Qiu,Shaohua Wu,Shaozeng Sun,Hui Liu,Longbin Yang,Guozhong Wang 한국화학공학회 2007 Korean Journal of Chemical Engineering Vol.24 No.4

research conducts a series of industrial tests on coal reburning of a 600 MW pulverized coal boilerfiring lignite, which is one part of a coal reburning demonstration project. When running steadily under 60 MW load,the boiler has an average NOx emission of 274 mg/m3 (O2 content in flue gas is converted to 6% ), the NOx emissionis reduced by 65.36% . In the meanwhile, loss of ignition (LOI) under coal reburning rarely increases. Three operationconditions - traditional air feeding, air staging and coal reburning - are realized, respectively, during the industrial tests,and the results indicate that coal reburning has the lowest NOx emission, while the traditional air feeding has the highestNOx x controlcan reach.

Mass transfer and reaction process of the wet desulfurization reactor with falling film by cross-flow scrubbing

Juncong Sai,Shaohua Wu,Rui Xu,Rui Sun,Yan Zhao,Yukun Qin 한국화학공학회 2007 Korean Journal of Chemical Engineering Vol.24 No.3

the present study, a series of wet flue gas desulfurization experiments have been carried out in com-parison with diferent slurry feeding ways, i.e., by series connection and by parallel connection, by means of cross-flow scrubbing with faling film. The experiment results show that there is optimal desulfurization performance forfer by cross-flow scrubbing model have been developed. The pH values of the outlet slurry inside the reactor and theion concentration distributions of H2SO3, HSO3 and SO32 along the axial direction of the tubes were obtained by an-alyzing and calculating the models. The calculation values agree well with the experimental values. It shows that themodels can predict well the ion concentration distributions along the axial direction of the tubes.

Crosslinked Ionic Alginate and Cellulose-based Hydrogels for Photoresponsive Drug Release Systems

Fang Zhou,Shaohua Wu,Chris Rader,Jianwei Ma,Shaojuan Chen,Xiaoyan Yuan,E Johan Foster 한국섬유공학회 2020 Fibers and polymers Vol.21 No.1

In this work, photosensitive alginate and cellulose-based hydrogels with interpenetrating polymer networks weresuccessfully prepared from alginate, TEMPO-oxidized cellulose nanofibers (TEMPO-CNFs) and polyacrylamide,crosslinked by both Fe3+ and N,N'-methylenebis-acrylamide. The obtained hydrogels showed a clear relationship between themechanical properties and the content of the TEMPO-CNFs. The results indicated that the mechanical properties ofcrosslinked hydrogels were enhanced with the mass ratio of TEMPO-CNFs and alginate increased from 1/2 to 2. Moreover,the crosslinked ionic alginate and cellulose-based hydrogels with various TEMPO-CNFs contents exhibited aninterconnected porous morphology with an average pore size of ca. 130 μm, and demonstrated an increased cumulativerelease amount of BSA drugs under the ultraviolet irradiation. This study demonstrated that the as-prepared photoresponsivehydrogels would have a potential application as local drug release systems for wound dressings.

Effects of Sb, Sr, and Bi on the material properties of cast Al-Si-Cu alloys produced through heated mold continuous casting

Mitsuhiro Okayasu,Shuhei Takeuchi,Shaohua Wu,Toshihiro Ochi 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.3

Rare earth metals can create a fine eutectic Si structure in cast Al-Si 10.6 -Cu 2.5 (ADC12) alloys produced through heated mold continuous casting. Fine and spherical eutectic Si phases are created in the ADC12 alloys through the addition of Sr 0.04 , and fine lamellar eutectic Si phases are created through Sb and Bi addition. Crystal orientation on the face perpendicular to the casting direction is formed by [110];however, this uniform formation is collapsed in the ADC12 alloy with an increasing amount of Sr addition, such as Sr > 0.04%. The shape of the eutectic Si is statically analyzed, and the effects of the eutectic Si characteristics on the mechanical properties are examined experimentally. On the one hand, the mechanical properties of the ADC12-Sr alloy increase with increasing Sr content because of the fine eutectic Si, the randomly orientated crystal formation, and so on. On the other hand, the material ductility increases in the ADC12 alloy with increasing addition of Sb and Bi elements. A high fracture strain of approximately 14% is obtained for the ADC12-Bi1.5 alloy.

Enhanced Performance of Organic Transistor Sensors using Porous Films

Longzhen Qiu,Lijun Zhang,Guobing Zhang,Shaohua Wu,Qinghe Wang 한국고분자학회 2017 한국고분자학회 학술대회 연구논문 초록집 Vol.42 No.2