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Excellent Strengthening of Low-Carbon Steel by Severe Free-End Torsion
Shijun Tan,Bo Song,Hongbing Chen,Xiaodong Tan,Risheng Qiu,Tingting Liu,Ning Guo,Shengfeng Guo 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.8
In this work, the effects of free-end torsion on microstructure and tensile property of low-carbon steel were investigated indetail. Low-carbon steels exhibited exceptionally high yield strength through severe torsion deformation. Such high hardeningeffect was mainly attributed to the severe lattice distortion, high density of dislocations and the change in grain shape. Moreover, a gradient deformation structure can be introduced by torsion deformation. The gradient-structure can generate ahigh hetero-deformation induced strengthening, which can increase the strain hardening capacity and remain high plasticity/toughness. Therefore, with increasing torsion angle from 700 to 2800 deg., the uniform elongation and the peak strength werelargely enhanced. After twisting 2800 deg., yield strength and peak strength can achieve 524 MPa and 675 MPa, respectively,and good tensile elongations (εf = 9.6%, εu = 7.4%) are remained.
Shijun Ji,Chengxin Jiang,Ji Zhao,Jilong Yang,Jili Wang,Handa Dai 한국물리학회 2019 Current Applied Physics Vol.19 No.11
In this paper, a dual-band metamaterial absorber (MMA) with wide-angle and polarization-insensitivity is proposed. The MMA consists of two copper layers with a layer of FR-4 between them. And its top layer consists of a cross-shaped resonator and a square ring resonator. The calculation result demonstrates that there are two distinct absorption peaks, whose absorptivity are 99.933% at 3.8441 GHz and 99.99% at 9.1094 GHz. And its thickness is only 1.34% of the wavelength of the lowest absorption frequency. The dual-band MMA shows polarization-insensitivity for normal incident wave and shows high absorptivity in a wide incident angle for both TE and TM polarization wave. In addition, we discuss the working mechanism. The influences of main parameters on the dual-band MMA's absorption are also analyzed. The proposed ultra-thin MMA has simple structure and high absorptivity, which has many potential applications, such as thermal radiometer, detection sensor, stealth technology.
Personal Remittances and Financial Development for Economic Growth in Economic Transition Countries
Shijun Cao,Sung Jin Kang 한국국제경제학회 2020 International Economic Journal Vol.34 No.3
This study investigates the effect of personal remittance inflows and financial development on the economic growth of 29 economic transition countries for the period of 2000–2015. Dynamic panel system GMM estimation results show that there is a positive relationship between remittance inflows and economic growth. It also shows that remittances and the level of financial development have a substitute relationship in promoting economic growth. So the remittance inflows have a positive effect on economic growth for the countries with low levels of financial development, but they have a negative effect on such growth for countries with moderate to high levels of financial development.
ShiJun Chen,Qi Zhang,Biao He,SuRong Huang,Dou-Dou Hui 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.1
In order to meet the thermal performance analysis accuracy requirements of high density permanent magnet synchronous motor (PMSM), a method of multi physical domain coupling thermal analysis based on control circuit, electromagnetic and thermal is presented. The circuit, electromagnetic, fluid, temperature and other physical domain are integrated and the temperature rise calculation method that considers the harmonic loss on the frequency conversion control as well as the loss non-uniformly distributed and directly mapped to the temperature field is closer to the actual situation. The key is to obtain the motor parameters, the realization of the vector control circuit and the accurate calculation and mapping of the loss. Taking a 48 slots 8 poles high density PMSM as an example, the temperature rise distribution of the key components is simulated, and the experimental platform is built. The temperature of the key components of the prototype machine is tested, which is in agreement with the simulation results. The validity and accuracy of the multi physical domain coupling thermal analysis method are verified.
Song Shijun,Xiong Chao,Yin Junhui,Yang Zhaoshu,Wang Lu 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.2
In this study, a hierarchical composite Kagome honeycomb sandwich (HCKHS) structure was manufactured based on the interlocking method, and its uniaxial compression performance was explored. Through experiments, the compressive strength, stiffness, energy absorption, and failure process of HCKHS specimens of seven different sizes were determined and compared. Mechanical analytical models were established, and the variation trend in the specific strength was predicted and compared with those of other advanced sandwich structures. The size effect of the HCKHS specimens was analyzed. The influence of a single variable on the core modulus, failure strength, and failure modes was discussed, and failure mechanism maps were drawn. The structure was optimized based on the maximum specific strength and engineering application, and the optimal size design ratio was obtained. The results showed that the HCKHS specimens exhibited excellent compressive properties with a convenient manufacturing process, making them suitable for lightweight applications in engineering. The optimization ideas presented herein are also applicable to other two-dimensional hierarchical or normal composite honeycomb sandwich structures with diamond, triangular, and hexagonal shapes.
ADVANCED TREATMENT OF LEACHATE BY MEMBRANE PROCESSES
GHIM, Shijun,OZAKI, Hiroaki,TERASHIMA, Yutaka 嶺南大學校 環境問題硏究所 1996 環境硏究 Vol.16 No.1
AbstractIn this research, we present the treatment results ofleachates from landfill sites of municipal solid wastes or artificial incineration ash leachate by the process of ASMF (activated sludge process with microfiltiation membrane) combined with LPRO (low pressure reverse osmosis membrane). The LPRO showed a high removal of recaldttant substances and inorganic salts. However, this process is not appropriate fer the direct leachate treatment. Thus, the ASMF using ceramic membrane of the pore size of 0.1 fim was applied as a pretreatment process.As the result of experiments, it was found that these processes could effectively remove both recalcitrant substances and inorganic salts of leachates. For example, the treatment efficiencies of artificial. incineration ash leachate by ASMF combined with LPRO were 99 % ofCODcr, 55 %ofT-N, 70 % of calcium, and 53 % of sodium. Therefere, it was confirmed that the process of ASMF combined with LPRO can become an alternative to the physico-chemical process in conventional leachate treatment plant. In this research, we present the treatment results of leachates from landfill sites of municipal solid wastes or artificial incineration ash leachate by the process of ASMF (activated sludge process with microfiltration membrane) combined with LPRO (low pressure reverse osmosis membrane). The LPRO showed a high removal of recalcitrant substances and inorganic salts. However, this process is not appropriate for the direct leachate treatment. Thus, the ASMF using ceramic membrane of the pore size of 0.1㎛ was applied as a pretreatment process. As the result of experiments, it was found that these processes could effectively remove both recalcitrant substances and inorganic salts of leachates. For example, the treatment efficiencies of artificial incineration ash leachate by ASMF combined with LPRO were 99% of COD_cr, 55% of T-N, 70% of calcium, and 53% of sodium. Therefore, it was confirmed that the process of ASMF combined with LPRO can become an alternative to the physico-chemical process in conventional leachate treatment plant.
Sun Shijun,Zhao Yun Duo 국제온돌학회 2013 International Journal of Ondol Vol.6 No.1
With the rapid development of the rural economy and vigorous promotion of energy-saving technologies, it is found through a field investigation that the new rural housing in the northeast of China shows new changes on green, energy-efficiency, health, comfort and beauty. The new rural housing mainly applied the technologies of composite energy-saving wall, double or three layers of glass energy saving windows and the roof benzene board insulation, heated in winter by Kang with the fuel of straw, corn stalks and other bio energy, which brings prominent energy-saving effect and the improved indoor environment significantly. The only or main function of the Kang is no longer the heating facilities in winter, but to play its unique benefits of comfort and health for sleep as a bed. the highlights of cultural traditions and customs in Cold rural area, the changes of the Kang are smaller and more exquisite. In the future, northeast rural housing should integrate the technolgies of residential structures, materials and kang further to promote rural sustainable development of society, economy.
녹색금융정책의 연구개발투자 자금조달에 대한 영향: 중국 상장기업을 대상으로
조시준 ( Shijun Cao ),강성진 ( Sung Jin Kang ) 한국외국어대학교 중국연구소 2023 中國硏究 Vol.95 No.-
Since the announcement of the “Green Credit Guideline” in 2012, the Chinese government has been implementing green credit policies. This study classified Chinese listed companies into credit-constrained and non-constrained groups based on the green credit policy, using data from 2012-2021. Through dynamic panel system GMM estimation, the similarities and differences in funding methods for R&D investment between the two groups were empirically analyzed. The results show that cash flow and stock issuance have a significant impact on R&D investment for credit-constrained companies, while cash flow and debt issuance have a significant impact for non-constrained companies. For private companies, debt issuance is not statistically significant for non-constrained companies as well, indicating that they consider debt issuance as a less important source of funding for R&D investment.
Establishment and Evaluation of National Power Index System: Evidence from Evidence‐Based Analysis
Li Shijun,Wang Dexin 인하대학교 국제관계연구소 2022 Pacific Focus Vol.37 No.1
National power is the basis of the current competition and game betweenglobal sovereign states. It is the organic integration and concentratedexpression of the multi-dimensional and complex factors of politics, econ-omy, society, culture, ecology, value system, and history of any country.Due to the complexity of national power and the non-objectivity of theassessment, the concept of national power and assessment must be con-structed using multiple levels of evidence. Therefore, this paper constructsa three-level evidence chain national power index system based on the sys-tematic literature review, public value theory, and expert scoring, andtakes the G20 countries as an example to measure the change and motiveforce of national power of the major countries in the world from 1992 to2017. Research shows that national power is fundamentally dependent onthe creation of multiple public values, and the trend of“weak countriesgetting weaker and strong countries getting stronger”among countries hasstrengthened. The increase of national power in different types of valuepower is not synchronous, but there are key points and outstandingimprovements.