Electrical Contact Characteristics of Ag-SnO₂ Materials with Increased SnO₂ Content

Pengyu Chen,Wei Liu,Yaping Wang 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.6

The electrical contact characteristics including temperature rise, contact resistance and arc erosion rate of the Ag-SnO₂ materials with increased SnO₂ content were investigated during the repeated make-and-break operations. The thickness of arcing melting layer reduces by half and the arc erosion rate decreases more than 70% under 10000 times operations at AC 10 A with the SnO₂ content increasing from 15 wt.% to 45 wt.%, on one hand, temperature rise and contact resistance increase obviously but could be reduced to the same order of conventional Ag-SnO₂ materials by increasing the contact force. The microstructure evolution and the effect of SnO₂ on the arc erosion, contact resistance were analyzed.

ASYMPTOTIC STABILITY OF STRONG SOLUTIONS FOR EVOLUTION EQUATIONS WITH NONLOCAL INITIAL CONDITIONS

Chen, Pengyu,Kong, Yibo,Li, Yongxiang Korean Mathematical Society 2018 대한수학회보 Vol.55 No.1

This paper is concerned with the global asymptotic stability of strong solutions for a class of semilinear evolution equations with nonlocal initial conditions on infinite interval. The discussion is based on analytic semigroups theory and the gradually regularization method. The results obtained in this paper improve and extend some related conclusions on this topic.

Asymptotic stability of strong solutions for evolution equations with nonlocal initial conditions

Pengyu Chen,Yibo Kong,Yongxiang Li 대한수학회 2018 대한수학회보 Vol.55 No.1

This paper is concerned with the global asymptotic stability of strong solutions for a class of semilinear evolution equations with nonlocal initial conditions on infinite interval. The discussion is based on analytic semigroups theory and the gradually regularization method. The results obtained in this paper improve and extend some related conclusions on this topic.

Electrical Contact Characteristics of Ag-SnO₂ Materials with Increased SnO₂ Content

Chen, Pengyu,Liu, Wei,Wang, Yaping The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.6

The electrical contact characteristics including temperature rise, contact resistance and arc erosion rate of the $Ag-SnO_2$ materials with increased $SnO_2$ content were investigated during the repeated make-and-break operations. The thickness of arcing melting layer reduces by half and the arc erosion rate decreases more than 70% under 10000 times operations at AC 10 A with the $SnO_2$ content increasing from 15 wt.% to 45 wt.%, on one hand, temperature rise and contact resistance increase obviously but could be reduced to the same order of conventional $Ag-SnO_2$ materials by increasing the contact force. The microstructure evolution and the effect of $SnO_2$ on the arc erosion, contact resistance were analyzed.

정부의 연구개발 보조금 정책이 기업 수익성에 미치는 영향에 대한 연구: 한국과 중국의 비교

진붕우(PENGYU CHEN),김상겸(Sang Kyum Kim) 연세대학교 동서문제연구원 2021 동서연구 Vol.33 No.2

기업의 연구개발투자는 기업의 성과개선을 위해 유효한 수단이지만, 특유의 외부성으로 인해 충분한 수준의 투자가 이루어지지 않는 것이 일반적이다. 이에, 세계 각국은 기업의 연구개발 투자를 활성시키고 기업성과 향상효과의 극대화를 위해 연구개발투자에 대한 보조금 지급정책을 활용하고 있다. 본 연구는 정부의 연구개발(R&D) 보조금이 기업 수익성에 미치는 영향에 대해 한국과 중국의 실증데이터를 통해 분석한 연구이다. 이를 위해 본 연구에서는 연구개발 성과와 관련한 Griliches 모형을 통해 정부 보조금이 기업의 연구개발 활동과 수익성에 미친 영향에 대해 살펴보았다. 또한 기업의 연구개발 행위가 수익성 향상에 유의미한 영향을 미치기 위해서는 일정한 시간이 소요됨을 고려하여, 각 변수별 시차를 적용하여 지연효과(lagged effect)를 검증하였다. 본 연구의 분석결과에 따르면, 연구개발 투자와 그 성과 사이의 시차를 전제하는 경우, 정부의 연구개발 보조금과 기업의 연구개발투자는 기업 수익성 개선에 유의한 양(+)의 영향을 미치며, 그 효과는 시차 증가에 따라 더욱 뚜렷해지는 것으로 나타났다. 반면, 중국의 경우 기업의 연구개발투자는 그 수익성 개선에 유의한 양(+)의 영향을 미치지만, 정부 보조금의 영향은 유의하지 않은 것으로 분석되었다. This study analyzes the effect of government R&D subsidies onto firm s R&D expenditure and its profitability, using actual empirical data from Korea and China. For this purpose, this study constructed a traditional Griliches model in order to find out the effect of government R&D subsidies on companies performance achievements in terms of profitability. Considering the time gap between the R&D activities and the firm s profitability, this study also performs additional econometrics analysis using lagged effect model. According to the results of the analysis, R&D subsidies from government and investment in Korean firms has a significant impact on firm s profitability. In contrast, however, R&D subsidies and firms R&D investment in China has a relatively small and insignificant impact on productivity, although time differences are taken into consideration.

Metal Adsorbate-Induced Plasmon Damping in Gold Nanorods: The Difference Between Metals

Pengyu Xu,Xuxing Lu,Junwei Zhao,Yue Li,Sheng Chen,Junfei Xue,Weihui Ou,Song Han,YAPING DING,Weihai Ni 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.9

We presented a single particle study on the metal adsorbate-induced plasmon damping in Au nanorods (AuNRs) through adsorbing clusters of different metals including Pt, Au and Ag. AuNRs with different longitudinal surface plasmon resonance (LSPR) wavelength were measured and investigated individually. Linewidth broadening, plasmon shift and reduction of plasmonic resonance of single AuNRs were studied and compared between Pt, Au and Ag adsorbates. The measured linewidths perfectly match the theoretical predictions of the billiard model with increased scattering coefficients resulted from the metal adsorbates. The results indicate that the plasmon damping in case of Ag is significantly weaker than Pt and Au, which can be attributed to longer relaxation time of free electrons in Ag and therefore less loss of the oscillating plasmon electrons. In contrast to the red shift observed from Au and Pt, blue shift of the LSPR is observed in case of Ag. It suggests that plasmonic properties brought by the metal adsorbates can exert dramatic influence on the nanoparticle that is adsorbed with. We believe that our study not only provides important understanding on plasmon damping but pave the road for the fabrication of complex nanostructures with two or more metal elements.

Preparation and properties of CNTs-Cu hybrids/epoxy superhydrophobic and anticorrosive coatings

Zhongbo Zhu,Shumei Kang,Hua Chen,Qingping Zhao,Zhaokang Huo,Pengyu Li,Qidong Cao,Chenshuo Lu 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.119 No.-

In this work, hydrophobized copper powders combined siloxane-modified carbon nanotubes(SHMWCNTs) to obtain intertwined hybrids of carbon nanotubes and copper (CNTs-Cu hybrids), andsuperhydrophobic CNTs-Cu hybrids/epoxy coatings were prepared on the surface of AH36 carbon steelby drop coating. The surface morphology and wettability of coatings were changed by adjusting the ratiosof SHMWCNTs to hydrophobized copper powders. The obtained coating can show a water contact angleof 167.2, a water sliding angle of 2.9, a plant oil contact angle of 134.3, and self-cleaning properties. Thecoating maintains superhydrophobicity after 300 tape-peeling times, exhibiting excellent mechanicaldurability. The fouled area percentages of chlorella on the coating and a pure epoxy resin were 0.23(±0.07)% and 12.18(±1.22)%, respectively, displaying anti-biofouling resistances. The coating has excellentcorrosion resistance, and its corrosion current density reached 9.55 10-8 A/cm2.

Effect of porosity gradient in cathode gas diffusion layer on electrochemical performance of proton exchange membrane fuel cells

Yang Guogang,Wang Hao,Su Fengmin,Li Shian,Zhang Guoling,Sun Juncai,Shen Qiuwan,Jiang Ziheng,Liao Jiadong,Chen Pengyu 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7

Proton exchange nembrane fuel cells (PEMFCs) are highly promising energy devices for future transportation and distributed power stations. The electrochemical performance of PEMFCs assembled with gas diffusion layer (GDL) of different porosity gradient distributions has been analyzed using the lattice Boltzmann method. A single-phase multi-component lattice Boltzmann model employing the active approach was developed to investigate the reactive gas flow within the GDL. Two types of GDLs with the same porosity, namely multilayer porosity gradient GDLs and linear porosity gradient GDLs, were generated to investigate the effect of the porosity gradient of the GDL on the electrochemical performance of PEMFC. The results show that the two types of porosity gradient GDL improve oxygen starvation problems and enhance water management, and that the GDLs with smaller porosity gradients can increase the mean current density. This paper develops the study of pore-scale analysis of PEMFC performance and can provide guidance for the design of GDL structures.