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CaiFeng Li 인하대학교 정석물류통상연구원 2009 인하대학교 정석물류통상연구원 학술대회 Vol.2009 No.10
In this paper, we address thoroughly the definition of supply chain from multiple angles and present two ideas both time-based competition and the demand-driven perspectiv. This paper analyzed the behaviours under the guidance of ideas. They are respectively adding value using time opportunity aiding information technology for end-consumer and suppliers, rising end-consumer expectations through the marketing perspective. But the proliferation of products and service, shorter product cycle"s 21st lead to respond quickly are not enough to consumer demands. The situation obliges to enterprise to construct agile supply chain to meet calling of the age. I believe that it advent and it will be a main stream of a fluid for the future.
Optoelectronic Characteristics of UV Photodetector Based on GaN/ZnO Nanorods p-i-n Heterostructures
Qingshan Li,Lichun Zhang,Fengzhou Zhao,Caifeng Wang,Feifei Wang,Ruizhi Huang 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.4
We demonstrate an efficient ultraviolet (UV) photodetector operating at room temperature based on n-ZnO nanorods/i-ZnO/p-GaN heterojunctions. We employ x-ray diffraction and field-emission scanning electron microscopy to confirm the high quality of the ZnO nanorods using an undoped ZnO film as the interlayer. Then, we investigate the photoelectric properties of the fabricated photodetector with UV light illumination under a different reverse bias. Based on the current-voltage curve, the photocurrent to dark current ratio is approximately 73.3 at −4 V. At zerobias voltage, the peak responsivity was 138.9 mA/W at 362 nm under front-illumination conditions. Time-varying measurements indicate the reproducibility and stability of the heterojunction photodetector.
Estimating equation for additive hazards model with censored length-biased data
Hongping Wu,Caifeng Du,Xiaosha Li 한국통계학회 2020 Journal of the Korean Statistical Society Vol.49 No.1
Aalen’s additive hazards model plays a very important role in survival analysis. In this paper we are interested in the problem of estimating regression coefficients in the additive hazards model with censored length-biased data. Through both of the parametric invariance of the proportional likelihood ratio model and the unique structure of length-biased data, we propose a pairwise pseudo-likelihood estimating equation, which only relies on the complete residual lifetimes in censored length-biased data. In addition, two combined estimating equations are also considered to estimate covariate coefficients. These estimators are proved to be consistent and asymptotically normal. In order to evaluate the performance of the proposed estimators in a finite sample, some simulations are conducted. Finally, a real data example is also provided.
Crystal Structure and Tautomerism Study of the Mono-protonated Metformin Salt
Xiaodan Wei,Yuhua Fan,Caifeng Bi,Xingchen Yan,Xia Zhang,Xin Li 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.12
A novel crystal, the mono-protonated metformin acetate (1), was obtained and characterized by elemental analysis, IR spectroscopy and X-ray crystallography. It was found that one of the imino group in the metformin cation was protonated along with the proton transfer from the secondary amino group to the other imino group. Its crystal structure was then compared with the previously reported diprotonated metformin oxalate (2). The difference between them is that the mono-protonated metformin cations can be linked by hydrogen bonding to form dimers while the diprotonated metformin cations cannot. Both of them are stabilized by intermolecular hydrogen bonds to assemble a 3-D supermolecular structure. The four potential tautomer of the monoprotonated metformin cation (tautomers 1a, 1b, 1c and 1d) were optimized and their single point energies were calculated by Density Functional Theory (DFT) B3LYP method based on the Polarized Continuum Model (PCM) in water, which shows that the most likely existed tautomer in human cells is the same in the crystal structure. Based on the optimized structure, their Wiberg bond orders, Natural Population Analysis (NPA) atomic charges, molecular electrostatic potential (MEP) maps were calculated to analyze their electronic structures, which were then compared with the corresponding values of the diprotonated metformin cation (cation 2) and the neutral metformin (compound 3). Finally, the possible tautomeric mechanism of the monoprotonated metformin cation was discussed based on the observed phenomena.
Crystal Structure and Tautomerism Study of the Mono-protonated Metformin Salt
Wei, Xiaodan,Fan, Yuhua,Bi, Caifeng,Yan, Xingchen,Zhang, Xia,Li, Xin Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.12
A novel crystal, the mono-protonated metformin acetate (1), was obtained and characterized by elemental analysis, IR spectroscopy and X-ray crystallography. It was found that one of the imino group in the metformin cation was protonated along with the proton transfer from the secondary amino group to the other imino group. Its crystal structure was then compared with the previously reported diprotonated metformin oxalate (2). The difference between them is that the mono-protonated metformin cations can be linked by hydrogen bonding to form dimers while the diprotonated metformin cations cannot. Both of them are stabilized by intermolecular hydrogen bonds to assemble a 3-D supermolecular structure. The four potential tautomer of the mono-protonated metformin cation (tautomers 1a, 1b, 1c and 1d) were optimized and their single point energies were calculated by Density Functional Theory (DFT) B3LYP method based on the Polarized Continuum Model (PCM) in water, which shows that the most likely existed tautomer in human cells is the same in the crystal structure. Based on the optimized structure, their Wiberg bond orders, Natural Population Analysis (NPA) atomic charges, molecular electrostatic potential (MEP) maps were calculated to analyze their electronic structures, which were then compared with the corresponding values of the diprotonated metformin cation (cation 2) and the neutral metformin (compound 3). Finally, the possible tautomeric mechanism of the mono-protonated metformin cation was discussed based on the observed phenomena.