중국 전자기업의 시장행위와 경쟁력 분석

서영인 ( Young In Seo ) 한중사회과학학회 2009 한중사회과학연구 Vol.7 No.1

Since reform and open policy, the Chinese electronic industry not only becomes the biggest mainstay industry in China, it also ranks in the second place in terms of the industrial size in the world, meanwhile, the market share of the Chinese electronic products is constantly upraising in the world market. According to the statistics and analysis in this paper, the development and achievement of the Chinese electronic industry are closely associated with the relevant effect of the foreign funded enterprises in China and the increasing market demand, of which, the foreign funded enterprises in China is more remarkable. But during the development of the Chinese electronic industry, the poor benefit still exists. The problem of the low profits of the Chinese electronic enterprises is more severe one, which influences negatively the stable development of the Chinese electronic enterprises. The reasons for the low profitability of the Chinese electronic enterprises attribute to low concentration, market conduct. Although the growth of the Chinese electronic enterprises is faster than that of the foreign enterprises, however, the integrated competitiveness of the Chinese electronic enterprises is far lower than their international competitors. According to the statistics and analysis on the competitiveness, the factors such as size and benefit are directly influence the integrated competitiveness of the Chinese electronic enterprises.

Electrical Conductivity of a Nondegenerate Electron Gas with a Complex Shaped Quantum Well

S. R. Figarova,T. H. ˙Ismayilov,G. N. Khasiyeva 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.8

In this paper, the electrical conductivity of a nondegenerate electron gas with a complex shaped quantum well is calculated. The conductivity’s dependences on the temperature and on the parameters of the quantum well are studied in the case of electron-phonon scattering. For scattering of electrons by polar optical phonons, the conductivity is shown to depend essentially on the temperature, as distinct from acoustical phonon scattering and to decrease with increasing temperature. Also, the conductivity decreases down to zero, with increasing potential of quantum well.

Conductivity‐Dependent Completion of Oxygen Reduction on Oxide Catalysts

Lee, Dong‐,Gyu,Gwon, Ohhun,Park, Han‐,Saem,Kim, Su Hwan,Yang, Juchan,Kwak, Sang Kyu,Kim, Guntae,Song, Hyun‐,Kon WILEY‐VCH Verlag 2015 Angewandte Chemie Vol.54 No.52

<P><B>Abstract</B></P><P>The electric conductivity‐dependence of the number of electrons transferred during the oxygen reduction reaction is presented. Intensive properties, such as the number of electrons transferred, are difficult to be considered conductivity‐dependent. Four different perovskite oxide catalysts of different conductivities were investigated with varying carbon contents. More conductive environments surrounding active sites, achieved by more conductive catalysts (providing internal electric pathways) or higher carbon content (providing external electric pathways), resulted in higher number of electrons transferred toward more complete 4e reduction of oxygen, and also changed the rate‐determining steps from two‐step 2e process to a single‐step 1e process. Experimental evidence of the conductivity dependency was described by a microscopic ohmic polarization model based on effective potential localized nearby the active sites.</P>

Effects of Cesium Salts on the Electrical Conductivity of the Weakly Ionized Gas in a Hypersonic MHD Channel

Hao Li,Peng Lu,Hulin Huang,Yining Zhang,Chenyuan Liu 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.5

To adequately utilize the high enthalpy of the weakly ionized gas and improve the performance of the magnetohydrodynamic generator (MHDG) in a hypersonic channel, cesium salts are homogeneously injected into the gas at the entrance of the MHD channel for elevating the gas electrical conductivity. The finite rate chemical dynamics and multi-species electrical conductivity model for seven-species (N2, O2, N, O, NO, NO+, e−) were adopted to simulate the electrical conductivity of the weakly ionized gas under different magnetic fields. The results demonstrate that the electrical conductivity of the weakly ionized gas with cesium salts is significantly higher than that without cesium salts due to two positive contributions of cesium salts, one is that a portion cesium atom ionize much more electrons, and the second is that cesium salts reduce the activation energy of N + O <-> NO + e− by 3.5 times, which accelerates the production rate of electrons. The electrical conductivity of the gas with cesium salts is decreased monotonically along the flow direction, which is contrary to the trend of that without cesium salts. The variation of the collision frequency plays a crucial role in the electrical conductivity of the gas without cesium salts, nevertheless, this effect is marginal on the gas with cesium salts. The magnetic fields have negative impacts on the electrical conductivity of the gas with/without cesium salts. Additionally, the MHDG power generation efficiency is augmented with B for the gas with cesium salts, whereas the trend is reversed for that without cesium salts.

First-principles calculations of the effect of Ge content on the electronic, mechanical and acoustic properties of Li17Si4-xGex

Xiaohong Li,Hong-Ling Cui,Rui-Zhou Zhang 한국물리학회 2019 Current Applied Physics Vol.19 No.6

The electronic, mechanical and acoustic properties of Li17Si4-xGex (x=0, 2.3, 3.08, 3.53, and 4) have been investigated by using first-principles calculations based on the density functional theory (DFT). The research shows that the bulk modulus B, Young's modulus E, shear modulus G, and hardness Hv gradually decrease with the increasing Ge content. Li17Si4-xGex have the brittle nature from the analysis of B/G ratio and Cauchy pressure. The maximum Young's moduli are all along [1 1 0] plane, and the sequence of degree of anisotropic property is Li17Ge4 > Li17Si0.48Ge3.52 > Li17Si0.92Ge3.08 > Li17Si1.7Ge2.3 > Li17Si4. The analysis of acoustic velocity shows that all the sound velocities decrease with the increasing Ge content for Li17Si4-xGex (x=0, 2.3, 3.08, 3.53, and 4), and the longitudinal wave along [111] direction is fastest for the studied compounds. Debye temperature ΘD, vt and vl decrease with the increasing Ge content. The minimum thermal conductivity decreases with the increasing Ge content, and Li17Si4-xGex have low thermal conductivities and are not potential thermal conductors. The analysis of electronic properties indicates that Li17Si4-xGex have the metal nature and anisotropic electrical conductivity. The electric conduction is improved with the increasing Ge content.

High-efficiency p–i–n organic light-emitting diodes with a novel n-doping electron transport layer

Wei Xu,M.A. Khan,Yu Bai,X.Y. Jiang,Z.L. Zhang,W.Q. Zhu 한국물리학회 2009 Current Applied Physics Vol.9 No.4

We demonstrate p–i–n organic light-emitting diodes (OLEDs) incorporating an n-doping transport layer which comprises 8-hydroxy-quinolinato lithium (Liq) doped into 4'7-diphyenyl-1,10-phenanthroline (Bphen) as ETL and a p-doping transport layer which includes tetrafluro-tetracyano-quinodimethane (F4-TCNQ) doped into 4,4',4''-tris(3-methylphenylphenylamono) triphenylamine (m-MTDATA). In order to examine the improvement in the conductivity of transport layers, hole-only and electron-only devices are fabricated. The current and power efficiency of organic light-emitting diodes have been improved significantly after introducing a novel n-doping (Bphen: 33 wt% Liq) layer as an electron transport layer (ETL) and a p-doping layer composed of m-MTDATA and F4-TCNQ as a hole transport layer (HTL). Compared with the control device (without doping), the current efficiency and power efficiency of Device C (most efficient) is enhanced by approximately 51% and 89%, respectively, while driving voltage is reduced by 29%. This improvement is attributed to the improved conductivity of the transport layers that leads to the efficient charge balance in the emission zone. We demonstrate p–i–n organic light-emitting diodes (OLEDs) incorporating an n-doping transport layer which comprises 8-hydroxy-quinolinato lithium (Liq) doped into 4'7-diphyenyl-1,10-phenanthroline (Bphen) as ETL and a p-doping transport layer which includes tetrafluro-tetracyano-quinodimethane (F4-TCNQ) doped into 4,4',4''-tris(3-methylphenylphenylamono) triphenylamine (m-MTDATA). In order to examine the improvement in the conductivity of transport layers, hole-only and electron-only devices are fabricated. The current and power efficiency of organic light-emitting diodes have been improved significantly after introducing a novel n-doping (Bphen: 33 wt% Liq) layer as an electron transport layer (ETL) and a p-doping layer composed of m-MTDATA and F4-TCNQ as a hole transport layer (HTL). Compared with the control device (without doping), the current efficiency and power efficiency of Device C (most efficient) is enhanced by approximately 51% and 89%, respectively, while driving voltage is reduced by 29%. This improvement is attributed to the improved conductivity of the transport layers that leads to the efficient charge balance in the emission zone.

A comparative experimental study on the cross-plane thermal conductivities of nano-constructed Sb2Te3/(Cu, Ag, Au, Pt) thermoelectric multilayer thin films

Yang Gang,Pan Jiahui,Fu Xuecheng,Hu Zhiyu,Wang Ying,Wu Zhimao,Mu Erzhen,Yan Xue-Jun,Lu Ming-Hui 나노기술연구협의회 2018 Nano Convergence Vol.5 No.22

Thermoelectric multilayer thin films used in nanoscale energy conversion have been receiving increasing attention in both academic research and industrial applications. Thermal transport across multilayer interface plays a key role in improving thermoelectric conversion efficiency. In this study, the cross-plane thermal conductivities of nano-constructed Sb2Te3/(Cu, Ag, Au, Pt) thermoelectric multilayer thin films have been measured using time-domain thermoreflectance method. The interface morphology features of multilayer thin film samples were characterized by using scanning and transmission electron microscopes. The effects of interface microstructure on the cross-plane thermal conductivities of the multilayer thin films have been extensively examined and the thermal transfer mechanism has been explored. The results indicated that electron–phonon coupling occurred at the semiconductor/metal interface that strongly affected the cross-plane thermal conductivity. By appropriately optimizing the period thickness of the metal layer, the cross-plane thermal conductivity can be effectively reduced, thereby improving the thermoelectric conversion efficiency. This work presents both experimental and theoretical understanding of the thermal transport properties of Sb2Te3/metal multilayer thin film junctions with important implications for exploring a novel approach to improving the thermoelectric conversion efficiency. Introduction Thermoelectric multilayer thin films used in nanoscale energy conversion have been receiving increasing attention in both academic research and industrial applications. Thermal transport across multilayer interface plays a key role in improving thermoelectric conversion efficiency. In this study, the cross-plane thermal conductivities of nano-constructed Sb2Te3/(Cu, Ag, Au, Pt) thermoelectric multilayer thin films have been measured using time-domain thermoreflectance method. The interface morphology features of multilayer thin film samples were characterized by using scanning and transmission electron microscopes. The effects of interface microstructure on the cross-plane thermal conductivities of the multilayer thin films have been extensively examined and the thermal transfer mechanism has been explored. The results indicated that electron–phonon coupling occurred at the semiconductor/metal interface that strongly affected the cross-plane thermal conductivity. By appropriately optimizing the period thickness of the metal layer, the cross-plane thermal conductivity can be effectively reduced, thereby improving the thermoelectric conversion efficiency. This work presents both experimental and theoretical understanding of the thermal transport properties of Sb2Te3/metal multilayer thin film junctions with important implications for exploring a novel approach to improving the thermoelectric conversion efficiency. Introduction

Effect of Y-doping on the phase relation and electrical properties of Fe-doped BaZrO₃

Kim, Dongyoung,Lee, Daae,Joo, Jong Hoon Elsevier 2018 Journal of the European Ceramic Society Vol.38 No.2

<P><B>Abstract</B></P> <P>The effects of the co-doping of Y in Fe-doped BaZrO<SUB>3</SUB> (BaZr<SUB>0.7-<I>y</I> </SUB>Fe<SUB>0.3</SUB>Y<I> <SUB>y</SUB> </I>O<SUB>3-</SUB> <I> <SUB>δ</SUB> </I>) on the phase relation and electrical properties are investigated in this study. While a single phase is formed up to <I>y</I> =0.1 by the substitution of Y for Zr-sites (phase-1), the amphoteric substitution of Y for both Zr-sites and Ba-site (phase-2) is observed above <I>y</I> =0.1. Electrical conductivity measurements suggest that <I>p</I>-type conduction prevails under an oxidizing atmosphere. The hole conductivity increases with an increase of Y concentration up to <I>y</I> =0.1, but a further increase of Y concentration causes a decrease in the conductivity. The maximum conductivities of both bulk and grain boundary are obtained at <I>y</I> =0.1, and a further increase of Y concentration leads to a decrease of the conductivity due to the possible formation of phase-2 with the partial replacement of Y for Ba-sites ( Y B a • ). Partial proton conductivity is also improved by Y-doping up to <I>y</I> =0.1, but a further doping cannot contribute to an increase in the proton conductivity. The results indicate that the mixed proton and hole conductivity of Fe-doped BaZrO<SUB>3</SUB> can be improved by the co-doping of a rare-earth acceptor (Y<SUP>3+</SUP>), but the doping level is limited to <I>y</I> =0.1 to avoid the formation of phase-2.</P>

Preparation of rGO-S-CPEs Composite Cathode and Electrochemical Performance of All-Solid-State Lithium-Sulfur Battery

Chen, Fei,Zhang, Gang,Zhang, Yiluo,Cao, Shiyu,Li, Jun The Korean Electrochemical Society 2022 Journal of electrochemical science and technology Vol.13 No.3

The application of polymer composite electrolyte in all-solid-state lithium-sulfur battery (ASSLSBs) can guarantee high energy density and improve the interface contact between electrolyte and electrode, which has a broader application prospect. However, the inherent insulation of the sulfur-cathode leads to a low electron/ion transfer rate. Carbon materials with high electronic conductivity and electrolyte materials with high ionic conductivity are usually selected to improve the electron/ion conduction of the composite cathode. In this work, PEO-LiTFSI-LLZO composite polymer electrolyte (CPE) with high ionic conductivity was prepared. The ionic conductivity was 1.16×10^-4 and 7.26×10^-4 S cm^-1 at 20 and 60℃, respectively. Meanwhile, the composite sulfur cathode was prepared with Sulfur, reduced graphene oxide and composite polymer electrolyte slurry (S-rGO-CPEs). In addition to improving the ion conductivity in the cathode, CPEs also replaces the role of binder. The influence of different contents of CPEs in the cathode material on the performance of the constructed battery was investigated. The results show that the electrochemical performance of the all-solid-state lithium-sulfur battery is the best when the content of the composite electrolyte in the cathode is 40%. Under the condition of 0.2C and 45℃, the charging and discharging capacity of the first cycle is 923 mAh g^-1, and the retention capacity is 653 mAh g^-1 after 50 cycles.

Comparative study on the preparation of conductive copper pastes with copper nanoparticles prepared by electron beam irradiation and chemical reduction

Pham, Long Quoc,Sohn, Jong Hwa,Park, Ji Hyun,Kang, Hyun Suk,Lee, Byung Cheol,Kang, Young Soo Elsevier 2011 Radiation physics and chemistry Vol.80 No.5

<P><B>Abstract</B></P><P>Copper nanoparticles with narrow size distribution of 5–7nm were synthesized by using electron beam irradiation. The copper nanoparticles were stable in ambient air for two months. TGA showed that the copper nanoparticles prepared by using electron beam irradiation have the higher wt% of pure copper metal compared with the one prepared by chemical reduction using hydrazine hydrate(N<SUB>2</SUB>H<SUB>4</SUB>·<I>x</I>H<SUB>2</SUB>O). The conductive copper paste with copper nanoparticles prepared by electron beam irradiation showed higher conductivity than the paste with copper nanoparticles prepared by chemical reduction with N<SUB>2</SUB>H<SUB>4</SUB> due to small size, less amount of surfactants on the surface and higher stability against the oxidation in ambient condition. The highest conductivity of copper paste was determined as 170Scm<SUP>−1</SUP> at 90wt% of copper nanoparticles in the paste.</P> <P><B>Research highlights</B></P><P>► Copper nanoparticles were synthesized by electron beam irradiation and chemical reduction. ► The copper nanoparticles synthesized by electron beam irradiation have narrower size distribution of 5–7nm and higher wt% of pure copper metal compared with the one synthesized by chemical reduction. ► Conductive pastes prepared by copper nanoparticles synthesized by electron beam irradiation show higher conductivity.</P>