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Yujie Yang,Xiansong Liu,Shuangjiu Feng,Xucai Kan,Qingrong Lv,Feng Hu,Jiangli Ni,Chaocheng Liu,Wei Wang 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.4
The microstructural, spectral, magnetic and electric properties of hexaferrites Ba0.40Sr0.60-xNdxFe12.00-xZnxO19 (0.00 ≤ x ≤ 0.30)synthesized by the solid-state reaction route have been studied. XRD results confirmed that the hexaferrites with Nd-Zncontent (x) of 0.00 ≤ x ≤ 0.24 were single M-type phase, and the hexaferrite with x = 0.30 exhibited the M-type phase andimpurity phase. The remanence (Br) increased with x from 0.00 to 0.06, and then decreased when x ≥ 0.06. The intrinsiccoercivity (Hcj) and magnetic induction coercivity (Hcb) decreased with x from 0.00 to 0.30. Br indicated a linear decreasingbehavior with increasing temperature from 20 oC to 140 oC. Hcj raised linearly with increasing temperature from 20 oC to 140oC. The value of aBr basically remained constant with Nd-Zn content (x). The value of aHcj increased with x from 0.00 to 0.12,and began to decrease when x ≥ 0.12. The electrical resitivity (ρ) presented a decreasing trend with x from 0.00 to 0.30.
Rapid Microwave Irradiation Synthesis and Photoelectrochemical Performance of Cu3BiS3 nanoparticles
Wei Wang,Guowei Zhi,Liu Liu,Yujie Fei,QinYang Sheng,Yushi Shi,Hanyu Yao,Hongqiang Qian 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.6
A photocatalytic material with high performance and low cost plays a decisive role in the industrialization of photocatalytichydrogen evolution. In this work, Cu3BiS3 nanoparticles were successfully synthesized by the microwave irradiationmethod, and the formation mechanism of Cu3BiS3 was studied. The Cu3BiS3 was a nanorod structure with 122 nm diameterand 41 nm length. The band gap was 1.31 eV and the EVB was located at 0.15 eV from the Mott-Schottky analysis. The Cu3BiS3 electrode exhibited an excellent HER performance with an onset potential of 870 mV, a Tafel slope of 251.07mV/dec. And the charge transfer resistance (Rct) of Cu3BiS3 electrode was 7.2 Ω. The electrode also revealed the goodphotoelectric response ability. The electrode also revealed the good photoelectric response ability and good stability bytime course of the photocurrents. This work provided a fast, low-cost method to prepare the Cu3BiS3 for photocatalysiswater splitting.
Dynamic performance of 6.5 kV SiC MOSFET body diodes and anti‑parallel Schottky barrier diodes
Yujie Du,Xinling Tang,Xiaoguang Wei,Shuai Sun,Fei Yang,Zhibin Zhao 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.6
For a silicon carbide (SiC) metal–oxide–semiconductor fi eld-eff ect transistor (MOSFET), both the body diode of the MOSFET and an anti-parallel diode can function as a freewheeling diode that carries reverse current. Selecting a suitable freewheeling method is particularly important to fully exploit the performance of high-voltage SiC MOSFET devices. In this study, based on the 6.5 kV SiC MOSFET and the Schottky barrier diode (SBD) developed by our research group, the dynamic characteristics of the MOSFET body diode, the SBD, and the parallel connection of the two are investigated. In addition, the influence of capacitive current on the dynamic characteristics is analyzed by establishing an equivalent circuit model. Test results show that when compared with the body diode, the SBD has an extremely low reverse recovery current, a lower capacitive current, and better reverse recovery temperature stability. Thus, the SBD is regarded as the most suitable freewheeling diode for the 6.5 kV SiC MOSFET. Finally, a package solution for the 6.5 kV SiC MOSFET and SBD is proposed.
Centralized P2P Management System Based on File and Peer Reputation
Wei Tian,Yuji Sekiya,Yasushi Wakahara,Yoshiaki Tanaka 대한전자공학회 2009 ITC-CSCC :International Technical Conference on Ci Vol.2009 No.7
In recent years, P2P file sharing systems have become one of the most popular applications in networks. However, because of the nature of the openness and anonymity of P2P applications, it is very hard to control peers that can join the system and also to trace the originating peers of shared files. Therefore, P2P systems have also become an avenue of attack and in practice a lot of malicious files are shared in P2P systems in addition to legitimate files. In order to manage P2P networks and prevent the malicious files from spreading, we propose a centralized P2P management system (C2MS) using the reputation of both file and peer. Some simulation results demonstrate that our proposed C2MS can work well even in serious attack situation.
Yujie Zhao,Yeda Lian,Lei Li,Xu Gong,Xianghai Chai,Wei Liu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.2
Pre-swirl nozzle is an important cooling component that is located inside of aero-engine and exposed to complex vibration excitation, and exploring its vibration characteristics and durability is of significant importance, especially for 3D printing pre-swirl nozzle. The present study provides a novel vibration test method based on equivalent installation stiffness. Firstly, the vibration characteristics of pre-swirl nozzle in real engine assembly state is calculated by the finite element method, and the equivalent constraint fixture is designed and checked based on this. The check results indicate that the designed fixture can well restore the installation stiffness of engine and the strength of the test fixture elements is enough in the vibration test process. Then, the modal characteristics of pre-swirl nozzle are measured by modal test, based on which the accuracy of the finite element model is verified. Finally, a test program of vibration durability is established to evaluate the vibration durability of pre-swirl nozzle, in which the excitation frequency is determined by combining logarithmic frequency sweep and linear frequency sweep and the location of maximum stress is determined based on a novel method (density increasing method). Besides, the calibration of relation between vibration stress and excitation amplitude is completed. Based on the proposed test program, vibration durability test is performed. The results show that the natural frequency of pre-swirl nozzle only decreases by 0.62 % after 5×10 7 cycles, which indicates that the specimen is always in the stage of fatigue crack initiation over the test duration.
Wei Ren,Yunfang Yu,Huangming Hong,Ying Wang,Quanlong Gao,Yongjian Chen,Peixian Chen,Jianli Zhao,Qiyun Ou,Dagui Lin,Tuping Fu,Yujie Tan,Chenchen Li,Xinxin Xie,Guolin Ye,Jun Tang,Herui Yao 대한암학회 2022 Cancer Research and Treatment Vol.54 No.4
Purpose This study aims to comprehensively evaluate the clinical efficacy of chemotherapy or endocrine therapy maintenance in metastatic breast cancer (MBC) patients. Materials and Methods The meta-analysis of randomized clinical trials (RCTs) and propensity score matching of multicenter cohort study evaluated MBC patients who underwent first-line chemotherapy or endocrine therapy maintenance. This study is registered with PROSPERO: CRD42017071858 and ClinicalTrials.gov: NCT04258163. Results A total of 2,867 patients from 15 RCTs and 760 patients from multicenter cohort were included. The results from meta-analysis showed that chemotherapy maintenance improved progression-free survival (PFS) (hazard ratio [HR], 0.63; 95% confidence interval [CI], 0.54 to 0.73; p < 0.001; moderate-quality evidence) and overall survival (OS) (HR, 0.87; 95% CI, 0.78 to 0.97; p=0.016; high-quality evidence) than observation. In the cohort study, for hormone receptor–positive MBC patients, chemotherapy maintenance improved PFS (HR, 0.67; 95% CI, 0.52 to 0.85; p < 0.001) and OS (HR, 0.55; 95% CI, 0.42 to 0.73; p < 0.001) compared with observation, and endocrine therapy maintenance also improved PFS (HR, 0.65; 95% CI, 0.53 to 0.80; p < 0.001) and OS (HR, 0.55; 95% CI, 0.44 to 0.69; p < 0.001). There were no differences between chemotherapy and endocrine therapy maintenance in PFS and OS (all p > 0.05). Regardless of the continuum or switch maintenance therapy, showed prolonged survival in MBC patients who were response to first-line treatment. Conclusion This study provided evidences for survival benefits of chemotherapy and endocrine therapy maintenance in MBC patients, and there was no difference efficacy between chemotherapy and endocrine therapy maintenance for hormone receptor–positive patients.
Urata, Yuji,Huang, Kuiyun,Im, Myungshin,Lee, Induk,Deng, Jinsong,Ip, WingHuen,Krimm, Hans,Liping, Xin,Ohno, Masanori,Qiu, Yulei,Sugita, Satoshi,Tashiro, Makoto,Wei, Jianyan,Yamaoka, Kazutaka,Zheng, We IOP Publishing 2009 ASTROPHYSICAL JOURNAL LETTERS - Vol.706 No.1
<P>We present multi-band results for GRB071010B based on Swift, Suzaku, and ground-based optical observations. This burst is an ideal target to evaluate the robustness of the E-peak(src) - E-iso and E-peak(src) - E-gamma relations, whose studies have been in stagnation due to the lack of the combined estimation of E-peak(src) and long-term optical monitoring. The joint prompt spectral fitting using Swift/Burst Alert Telescope and Suzaku/Wide-band All-sky Monitor data yielded the spectral peak energy as E-peak(src) of 86.5(-6.3)(+6.4) keV and E-iso of 2.25(-0.16)(+0.19) x 10(52) erg with z = 0.947. The optical afterglow light curve is well fitted by a simple power law with temporal index alpha = -0.60 +/- 0.02. The lower limit of temporal break in the optical light curve is 9.8 days. Our multi-wavelength analysis reveals that GRB071010B follows E-peak(src) - E-iso but violates the E-peak(src) - E-gamma and E-iso - E-peak(src) - t(jet)(src) at more than the 3 sigma level.</P>
Shuai Ji,Yujie Wang,Shikai Gao,Xian Shao,Wei Cui,Yan Du,Mengzhe Guo,Daoquan Tang 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-
Lots of minor constituents in herbal medicines have shown great potential to devolve into leadcompounds, and their extraction is attracting more and more attention in pharmaceutical industry. Thisstudy provided an example that showed efficient and selective extraction of minor bioactive naturalproducts (prenylatedflavonoids with anti-cancer activities) from an herbal medicine (licorice) using pureionic liquids as green solvents. After investigation of a variety of hydrophobic ionic liquids withultrasonic-assisted extraction, we found that [C8MIM]BF4 (1-octyl-3-methylimidazolium tetrafluor-oborate) was the most effective one for extraction offive representative compounds (isoangustone A,glycycoumarin, licoisoflavanone, licoricidin and glabridin), and solvent to solid ratio, extraction time,extraction temperature and soaking time were then optimized through single-factor experiments andresponse surface methodology. As a result, the established method had significantly higher extractionselectivity than conventional organic solvents, which could be attributed to significant physical change oflicorice microstructures after extraction, as well as strong interactions (especially hydrogen bondinteractions) between [C8MIM]BF4 and prenylatedflavonoids by mechanism study. In addition, 78.92% ofthe extracted prenylatedflavonoids could be readily recovered from [C8MIM]BF4 by using reversed-phasesolid phase extraction, and the recyclability of [C8MIM]BF4 was also confirmed.
Property Assessment of High-Performance Concrete Containing Three Types of Fibers
Hua Huang,Yujie Yuan,Wei Zhang,Liang Zhu 한국콘크리트학회 2021 International Journal of Concrete Structures and M Vol.15 No.6
This study investigated the mechanical properties and the effects of the volume fraction for carbon fibers (CF-VF), polypropylene fibers (PPF-VF) and aramid fibers (AF-VF) with a fixed aspect ratio of 650 for the carbon fibers, 400 for the polypropylene fibers and 900 for the aramid fibers in hybrid fiber-reinforced concrete (HFRC). Furthermore, compressive, splitting tensile and flexural tensile tests were carried out to obtain the optimal total volume fraction for the three types of fibers, as well as the optimal ratio between the CF-VF, PPF-VF and AF-VF. In addition, stress-strain curves of normal concrete and HFRC were examined to explore the whole mechanical process. The results indicated the CF-VF, PPF-VF and AF-VF have a significant effect on the tensile and flexural strengths of HFRC. The HFRC with a fiber additional ratio of 25:50:25 had the best hybrid effect. Moreover, a calculation method based on the compressive strength of normal concrete and HFRC and the volume fraction is proposed to calculate the strength of HFRC in engineering as a reference. Besides, a uniaxial compression constitutive mathematical model of normal concrete and HFRC is established.