Safety Evaluation of Underground Gas Pipe under Blasting of Subway Connected Aisle: A Case Study

Yumin Yang,Zhongwei Cai,Nan Jiang,Chuanbo Zhou,Haibo Li 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.2

How to ensure the underground gas pipe’s safety under blasting construction of subway connected aisles is a key problem in tunnel construction. Based on the blasting excavation project of Wuhan Rail Transit Line 8 phase II, the numerical model whose reliability is verified by field monitoring data is established by ANSYS/LS-DYNA to analyze the dynamic underground gas pipe’s dynamic characteristics under blasting excavation of the connected aisle. According to the piping design code, the allowable effective stress control standard of underground pipe is proposed to evaluate the underground pipe’s safety under the blasting. The results show that: with the advance of blasting excavation, the position of the most dangerous section will change constantly and the pipe’s peak particle velocity (PPV) will appear an obvious amplification phenomenon in both sides of metro tunnels. The pipe’s PPV is greater than the ground surface’s PPV. A mathematical model is established to predict the pipeline’s PPV based on the linear relationship between the pipeline and the ground surface. According to the correlation between PPV and von-Mises stress of gas pipeline, a mathematical model between the pipe’s von-Mises stress and distance is established to predict the pipeline’s safety, which can provide guidance for actual blasting engineering.

Quinoxaline-Based Wide Band Gap Polymers for Efficient Nonfullerene Organic Solar Cells with Large Open-Circuit Voltages

Yang, Jie,Uddin, Mohammad Afsar,Tang, Yumin,Wang, Yulun,Wang, Yang,Su, Huimin,Gao, Rutian,Chen, Zhi-Kuan,Dai, Junfeng,Woo, Han Young,Guo, Xugang American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.27

<P>We present here a series of wide-band-gap (<I>E</I><SUB>g</SUB>: >1.8 eV) polymer donors by incorporating thiophene-flanked phenylene as an electron-donating unit and quinoxaline as an electron-accepting co-unit to attain large open-circuit voltages (<I>V</I><SUB>oc</SUB>s) and short-circuit currents (<I>J</I><SUB>sc</SUB>s) in nonfullerene organic solar cells (OSCs). Fluorination was utilized to fine-tailor the energetics of polymer frontier molecular orbitals (FMOs) by replacing a variable number of H atoms on the phenylene moiety with F. It was found that fluorination can effectively modulate the polymer backbone planarity through intramolecular noncovalent S···F and/or H···F interactions. Polymers (P2-P4) show an improved molecular packing with a favorable face-on orientation compared to their nonfluorinated analogue (P1), which is critical to charge carrier transport and collection. When mixed with IDIC, a nonfullerene acceptor, P3 with two F atoms, achieves a remarkable <I>V</I><SUB>oc</SUB> of 1.00 V and a large <I>J</I><SUB>sc</SUB> of 15.99 mA/cm<SUP>2</SUP>, simultaneously, yielding a power-conversion efficiency (PCE) of 9.7%. Notably, the 1.00 V <I>V</I><SUB>oc</SUB> is among the largest values in the IDIC-based OSCs, leading to a small energy loss (<I>E</I><SUB>loss</SUB>: 0.62 eV) while maintaining a large PCE. The P3:IDIC blend shows an efficient exciton dissociation through hole transfer even under a small energy offset of 0.16 eV. Further fluorination leads to the polymer P4 with increased chain-twisting and mismatched FMO levels with IDIC, showing the lowest PCE of 2.93%. The results demonstrate that quinoxaline-based copolymers are promising donors for efficient OSCs and the fluorination needs to be fine-adjusted to optimize the interchain packing and physicochemical properties of polymers. Additionally, the structure-property correlations from this work provide useful insights for developing wide-band-gap polymers with low-lying highest occupied molecular orbitals to minimize <I>E</I><SUB>loss</SUB> and maximize <I>V</I><SUB>oc</SUB> in nonfullerene OSCs for efficient power conversion.</P> [FIG OMISSION]</BR>

Backbone Coplanarity Tuning of 1,4-Di(3-alkoxy-2-thienyl)-2,5-difluorophenylene-Based Wide Bandgap Polymers for Efficient Organic Solar Cells Processed from Nonhalogenated Solvent

Liao, Qiaogan,Yang, Kun,Chen, Jianhua,Koh, Chang Woo,Tang, Yumin,Su, Mengyao,Wang, Yang,Yang, Yinhua,Feng, Xiyuan,He, Zhubing,Woo, Han Young,Guo, Xugang American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.34

<P>Halogenated solvents are prevailingly used in the fabrication of nonfullerene organic solar cells (NF-OSCs) at the current stage, imposing significant restraints on their practical applications. By copolymerizing phthalimide or thieno[3,4-<I>c</I>]pyrrole-4,6-dione (TPD) with 1,4-di(3-alkoxy-2-thienyl)-2,5-difluorophenylene (DOTFP), which features intramolecular noncovalent interactions, the backbone planarity of the resulting DOTFP-based polymers can be effectively tuned, yielding distinct solubilities, aggregation characters, and chain packing properties. Polymer DOTFP-PhI with a more twisted backbone showed a lower degree of aggregation in solution but an increased film crystallinity than polymer DOTFP-TPD. An organic thin-film transistor and NF-OSC based on DOTFP-PhI, processed with a nonhalogenated solvent, exhibited a high hole mobility up to 1.20 cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP> and a promising power conversion efficiency up to 10.65%, respectively. The results demonstrate that DOTFP is a promising building block for constructing wide bandgap polymers and backbone coplanarity tuning is an effective strategy to develop high-performance organic semiconductors processable with a nonhalogenated solvent.</P> [FIG OMISSION]</BR>

ARCA-An Adaptive Routing Protocol for Converged Ad-Hoc and Cellular Networks

Wu, Yumin,Yang, Kun,Chen, Hsiao-Hwa The Korea Institute of Information and Commucation 2006 Journal of communications and networks Vol.8 No.4

This paper proposes an adaptive routing protocol called ARCA for converged ad-hoc and cellular network (CACN). Due to the limitation of both bandwidth and transmission range in a cell, a mobile host (MH) may not be able to make a call during busy time. CACN offers a flexible traffic diversion mechanism that allows a MH to use the bandwidth in another cell to ease the congestion problem and increase the throughput in a cellular network. Based on the presentation of CACN's physical characteristics, the paper details the design issues and operation of the adaptive routing protocol for CACN (ARCA). Detailed numerical analysis is presented in terms of both route request rejection rate and routing overhead, which, along with the simulation results, have indicated the effectiveness and efficiency of the ARCA protocol.

Thermodynamics of fluoride-based molten fluxes for extraction of magnesium through the low temperature solid oxide membrane (LT-SOM) process

Lee, Yumin,Yang, Jae Kyo,Park, Joo Hyun Elsevier 2018 CALPHAD, computer coupling of phase diagrams and t Vol.62 No.-

<P><B>Abstract</B></P> <P>The melt quenching experiments and thermodynamic calculations of phase diagrams were carried out to investigate potential additives for the low temperature solid oxide membrane (LT-SOM) magnesium extraction process. The solubility of MgO, which is a major source of magnesium extraction, was also measured in the molten fluoride fluxes. The solubility of MgO in the 46.5MgF<SUB>2</SUB>-46.5CaF<SUB>2</SUB>-7LiF and 45MgF<SUB>2</SUB>-45CaF<SUB>2</SUB>-10NaF (wt%) systems reached 3.4 and 1.9 wt% at 1473 K, respectively, and 1.5 wt% MgO in both fluxes at 1223 K. In addition, the 45MgF<SUB>2</SUB>-55CaF<SUB>2</SUB> binary eutectic flux, which has been widely used in SOM process, could dissolve up to 2.3 wt% MgO at 1473 K. This value is significantly lower than the literature value, <I>i.e.</I> 10 wt% MgO. From the evaluation of the activity coefficient of MgO in the 46.5MgF<SUB>2</SUB>-46.5CaF<SUB>2</SUB>-7LiF and 45MgF<SUB>2</SUB>-45CaF<SUB>2</SUB>-10NaF fluxes under MgO saturation, it was confirmed that the stability of MgO in the 7LiF flux is greater than that in the 10NaF flux. Hence, the driving force of MgO dissolution into the 7LiF flux is higher than that into the 10NaF flux. The newly developed molten flux for magnesium extraction using the LT-SOM process with an operating temperature lower than 1273 K is the 46.5MgF<SUB>2</SUB>-46.5CaF<SUB>2</SUB>-7LiF system.</P>

Single layer retarder with negative dispersion of birefringence and wide field-of-view

Hwang, Jiyong,Yang, Seungbin,Choi, Yu-Jin,Lee, Yumin,Jeong, Kwang-Un,Lee, Ji-Hoon The Optical Society 2016 Optics express Vol.24 No.17

<P>A single layer retarder possessing negative dispersion (ND) of birefringence as well as wide field-of-view (FOV) was long-term objective in optical science. We synthesized new guest reactive monomers with x-shape and mixed them with the host smectic reactive mesogen. The host-guest molecules formed two dimensionally self-organized nanostructure and showed both the ND of birefringence and wide FOV properties. We simulated the antireflection property of a circular polarizer using the optical properties of the retarder. The average reflectance of the retarder was 0.52% which was much smaller than that of the commercial single layer ND retarder 1.83%. (C) 2016 Optical Society of America</P>

Backbone Conformation Tuning of Carboxylate-Functionalized Wide Band Gap Polymers for Efficient Non-Fullerene Organic Solar Cells

Chen, Jianhua,Wang, Lei,Yang, Jie,Yang, Kun,Uddin, Mohammad Afsar,Tang, Yumin,Zhou, Xin,Liao, Qiaogan,Yu, Jianwei,Liu, Bin,Woo, Han Young,Guo, Xugang American Chemical Society 2019 Macromolecules Vol.52 No.1

<P>Two carboxylate-functionalized wide band gap polymers, 2TC-TT-BDTFT and 2T-TTC-BDTFT, which feature a fluorinated benzodithiophene (BDTFT)-<I>alt</I>-2,5-di(thiophen-2-yl)thieno[3,2-<I>b</I>]thiophene (2T-TT) backbone having different carboxylate attaching positions, were designed and synthesized. By variation of the substitution position of carboxylate groups on the 2T-TT unit, the backbone conformation of the designed building blocks 2TC-TT and 2T-TTC and their corresponding donor-acceptor polymers was fine-tuned as demonstrated by single crystal study and DFT calculation, thus yielding a large device performance difference in organic solar cells. As a result of the relatively higher planarity of the 2T-TTC unit in which the two carboxylate groups were attached on the inner thieno[3,2-<I>b</I>]thiophene moiety, the 2T-TTC-BDTFT polymer exhibited a red-shifted UV-vis absorption, stronger aggregation, and improved charge transport property than its polymer analogue 2TC-TT-BDTFT, in which the two outer thiophene rings were functionalized with carboxylate groups. Benefiting from the improved exciton dissociation and charge collection efficiency, better film morphology, and higher photoresponse, non-fullerene organic solar cells based on 2T-TTC-BDTFT:m-ITIC achieved a power conversion efficiency (PCE) of 11.15% with a fill factor (FF) of ∼70%, while the 2TC-TT-BDTFT:m-ITIC cells showed a relatively lower PCE of 9.65% and FF of 59.31%. The much higher FF of 2T-TTC-BDTFT-based solar cells reflects the great merit of the carboxylation on thienothiophene moiety rather than the outer thiophene counterpart. Therefore, the modulation of the carboxylate position on polymer backbones is an efficient strategy to tune the backbone conformation, interchain packing, film morphology, and the resulting optical, electrical, and photovoltaic properties. Moreover, both the 2T-TTC-BDTFT:m-ITIC and 2TC-TT-BDTFT:m-ITIC solar cells showed excellent stability during annealing and long-term storage. These results demonstrate that carboxylate-functionalized 2T-TTC and 2TC-TT have great potentials as a weak electron-accepting building block for wide band gap polymers for high-performance non-fullerene organic solar cells, and the carboxylate position on the polymer backbones is critical for performance improvement of organic photovoltaic devices.</P> [FIG OMISSION]</BR>

ZNF435, a Novel Human SCAN-containing Zinc Finger Protein, Inhibits AP-1-mediated Transcriptional Activation

Xing Gu,Mei Zheng,Xiangwei Fei,Zhenxing Yang,Fan Li,Chaoneng Ji,Yi Xie,Yumin Mao 한국분자세포생물학회 2007 Molecules and cells Vol.23 No.3

기후변화로 인한 꿀벌의 출현일과 개화일 편차 추이 분석

황승현(Seunghyun Hwang),배재훈(Jaehoon Bae),서유민(Yumin Seo),양지원(Jiwon Yang),정희지(Huiji Jeong),최성빈(Seongbin Choi) 대한지리학회 2022 대한지리학회 학술대회논문집 Vol.2022 No.6

Effects of puerarin on the Akt signaling pathway in bovine preadipocyte differentiation

Yun, Jinyan,Yu, Yongsheng,Zhou, Guoli,Luo, Xiaotong,Jin, Haiguo,Zhao, Yumin,Cao, Yang Asian Australasian Association of Animal Productio 2020 Animal Bioscience Vol.33 No.1

Objective: Puerarin has the potential of regulating the differentiation of preadipocytes, but its mechanism of action has not yet been elucidated. Adipocytes found in adipose tissue, the main endocrine organ, are the main sites of lipid deposition, and are widely used as a cell model in the study of in vitro fat deposition. This study aimed to investigate the effects of puerarin on adipogenesis in vitro. Methods: Puerarin was added to the culture medium during the process of adipogenesis. The proliferation and differentiation of bovine preadipocytes was measured through cell viability and staining with oil red O. The content of triacylglycerol was measured using a triglyceride assay kit. The mRNA and protein expression levels of adipogenic genes, peroxisome proliferator-activated receptor-γ (PPARγ) and CCAAT/enhancer-binding protein-α, were measured using quantitative real-time polymerase chain reaction and western blotting, respectively. Results: The addition of puerarin significantly increased adipogenesis of bovine preadipocytes and enhanced the mRNA and protein level expression of PPARγ (p<0.01). The expression of P-Akt increased after adipogenic hormonal induction, whereas puerarin significantly increased PPARγ expression by promoting the Akt signaling component, P-Akt. The mechanism of adipogenesis was found to be related to the phosphorylation level of Ser473, which may activate the downstream signaling of the Akt pathway. Conclusion: Puerarin was able to promote the differentiation of preadipocytes and improve fat deposition in cattle. The mechanism of adipogenesis was found to be related to the phosphorylation level of Ser473.