A cohesive model for concrete mesostructure considering friction effect between cracks

Yi-qun Huang,Shao-wei Hu 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.24 No.1

Compressive ability is one of the most important mechanical properties of concrete material .The compressive failure process of concrete is pretty complex with internal tension, shear damage and friction between cracks. To simulate the complex fracture process of concrete at meso level, methodology for meso-structural analysis of concrete specimens is developed; the zero thickness cohesive elements are pre-inserted to simulate the crack initiation and propagation; the constitutive applied in cohesive element is established to describe the mechanism of crack separation, closure and friction behavior between the fracture surfaces. Aseries of simulations were carried out based on the model proposed in this paper. The results reproduced the main fracture and mechanical feature of concrete under compression condition. The effect of key material parameters, structure size, and aggregate content on the concrete fracture pattern and loading carrying capacities was investigated. It is found that the inner friction coefficient has a significant influence on the compression character of concrete, the compression strength raises linearly with the increase of the inner friction coefficient, and the fracture pattern is sensitive to the mesostructure of concrete.

Innovative displacement-based beam-column element with shear deformation and imperfection

Yi-Qun Tang,Yue-Yang Ding,Yao-Peng Liu,Siu-Lai Chan,Er-Feng Du 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.1

The pointwise equilibrium polynomial (PEP) element considering local second-order effect has been widely used in direct analysis of many practical engineering structures. However, it was derived according to Euler-Bernoulli beam theory and therefore it cannot consider shear deformation, which may lead to inaccurate prediction for deep beams. In this paper, a novel beam-column element based on Timoshenko beam theory is proposed to overcome the drawback of PEP element. A fifth-order polynomial is adopted for the lateral deflection of the proposed element, while a quadric shear strain field based on equilibrium equation is assumed for transverse shear deformation. Further, an additional quadric function is adopted in this new element to account for member initial geometrical imperfection. In conjunction with a reliable and effective three-dimensional (3D) corotational technique, the proposed element can consider both member initial imperfection and transverse shear deformation for second-order direct analysis of frame structures. Some benchmark problems are provided to demonstrate the accuracy and high performance of the proposed element. The significant adverse influence on structural behaviors due to shear deformation and initial imperfection is also discussed.

한국과 중국의 국제 전자상거래 촉진방안

호일군(Yi-Qun Hu) 성균관대학교 무역연구소 2019 Asian Trade Risk Management(ATRM) Vol.3 No.2

국제 전자상거래의 빠른 성장이 글로벌 무역 구조를 바꾸고 있다. 많은 나라가 국제 전자상거래의 발전을 촉진하고 있고 새로운 글로벌 무역 구조에서 주동적인 지위를 차지하기를 희망한다. 중국은 처음으로 한-중 FTA 협정문에서 ‘전자상거래’ 규정을 세우고 협력을 통하여 전자상거래의 발전을 촉진하고 있다. 한중 양국의 국제 전자상거래의 발전은 빠르지만 양국의 국제 전자상거래 시장과 경영방식에는 큰 차이가 있다. 본 논문은 거시적, 미시적인 각도에서 한중 국제 전자상거래의 특징을 비교 분석하였다. 그리고 한-중 FTA가 양국 간 국제 전자상거래에 미치는 영향을 토대로 국가와 기업의 입장에서 한국과 중국 국제 전자상거래의 발전에 대한 건의를 제시한다. This paper tries to show analysis of e-commerce between Korea and China and its promotion schedule. The rapid growth of cross-border e-commerce is changing the structure of global trade. Based on the effects of the Korea-China FTA on cross - border e-commerce between the two countries, exports and imports of cross-border electronic commerce platforms such as AliExpress, Gmarket, Tmall Global and Malltail were compared and analyzed in terms of microscopic aspect. Finally this paper proposes the development of cross - border e - commerce in Korea and China from the standpoint of the state and enterprises.

Curcumin Analogue A501 induces G2/M Arrest and Apoptosis in Non-small Cell Lung Cancer Cells

Xia, Yi-Qun,Wei, Xiao-Yan,Li, Wu-Lan,Kanchana, Karvannan,Xu, Chao-Chao,Chen, Da-Hui,Chou, Pei-Hong,Jin, Rong,Wu, Jian-Zhang,Liang, Guang Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.16

Curcumin and its analogues have been reported to exert anti-cancer activity against a variety of tumors. Here, we reported A501, a new curcumin analogue. The effect of A501 on cell viability was detected by MTT assay, the result showed that A501 had a better inhibiting effect on the four non-small cell lung cancer (NSCLC) cells than that of curcumin. Moreover, Colony forming experiment showed A501 significant restrained cell proliferation. Flow cytometry displayed A501 can cause G2/M arrest and induce apoptosis. Western blotting showed that A501 decreased the expression of cyclinB1, cdc-2, bcl-2, while increased the expression of p53, cleaved caspase-3 and bax. In conclusion, curcumin analogues A501 played antitumor activity by inhibiting cell proliferation and inducing apoptosis of NSCLC cells. And it was likely to be a promising starting point for the development of curcumin-based anticancer drugs.

Development of a Loop-Mediated Isothermal Amplification Assay for Rapid Detection of Nocardia salmonicida, the Causative Agent of Nocardiosis in Fish

( Qun Xia Li ),( Hong Lian Zhang ),( Yi Shan Lu ),( Jia Cai ),( Bei Wang ),( Ji Chang Jian ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.3

Nocardia salmonicida is one of the main pathogens of fish nocardiosis. The purpose of this study was to build a loop-mediated isothermal amplification (LAMP) method for the rapid and sensitive detection of N. salmonicida. A set of four primers were designed from the 16S-23S rRNA intergenic spacer region of N. salmonicida, and conditions for LAMP were optimized as incubating all the reagents for 60 min at 64°C. LAMP products were judged with agar gel electrophoresis as well as with the naked eye after the addition of SYBR Green I. Results showed the sensitivity of the LAMP assay was 1.68 × 103 CFU/ml (16.8 CFU per reaction) and 10-fold higher than that of PCR. The LAMP method was also effectively applied to detect N. salmonicida in diseased fish samples, and it may potentially facilitate the surveillance and early diagnosis of fish nocardiosis.

How Do Structural Oil Price Shocks Affect China’s Investor Sentiment? The Critical Role of OPEC Oil Supply Shocks

Yi-Shuai Ren,Yong Jiang,Chao-Qun Ma,Olaf Weber 한국증권학회 2021 Asia-Pacific Journal of Financial Studies Vol.50 No.5

This paper applies a modified structural vector autoregressive (SVAR) model to explore whether explicit structural oil price shocks affect investor sentiment in China’s stock market. The results indicate that China’s investor sentiment responds significantly positively to OPEC supply shocks, while it responds significantly negatively to oil-specific demand shocks. However, China’s stock investor sentiment does not respond to aggregate demand shocks and non-OPEC supply shocks. In addition, OPEC supply shocks and oil-specific demand shocks have greater explanatory power for variations in stock investor sentiment through variance decomposition.

Thermal Problems and Methods in Invasive Microwave Coagulation Therapy

Qun Nan,Jianshu Peng,Youjun Liu,Yi Zengon 대한의료정보학회 2007 Healthcare Informatics Research Vol.13 No.2

Objective: To study some thermal problems in invasive microwave coagulation (IMC) therapy. Methods: Temperature fields predicts, limitation and remedy methods of the Pennes bioheat transfer equation during the temperature distribution analyses and how to kill a large anomalistic tumor for only once were discussed. Results: The coagulation area between the simulations and actual measured results showed good correspondence. Blood flow influenced the rise in temperature significantly. Conclusions: Thermal distribution with computer simulation in invasive microwave coagulation therapy is an accurate and reliable method. (Journal of Korean Society of Medical Informatics 13-2, 159-163, 2007)

Transcriptional Analysis of 10 Selected Genes in a Model of Penicillin G Induced Persistence of Chlamydophila psittaci in HeLa Cells

( Yan Qun Hu ),( Li Li Chen ),( Chuan Wang ),( Ya Feng Xie ),( Zhi Xi Chen ),( Liang Zhuan Liu ),( Ze Hong Su ),( Yi Mou Wu ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.8

Chlamydophila psittaci is an important intracellular pathogen. Persistent infection is an important state of the host-parasite interaction in this chlamydial infection, which plays a significant role in spreading the organism within animal populations and in causing chronic chlamydiosis and serious sequelae. In this study, a C. psittaci persistent infection cell model was induced by penicillin G, and real-time quantitative PCR was used to study the transcriptional levels of 10 C. psittaci genes (dnaA, dnaK, ftsW, ftsY, grpE, rpsD, incC, omcB, CPSIT_0846, and CPSIT_0042) in acute and penicillin-G-induced persistent infection cultures. Compared with the acute cultures, the penicillin-G-treated cultures showed a reduced chlamydial inclusion size and a significantly decreased number of elementary body particles. Additionally, some enlarged aberrant reticulate body particles were present in the penicillin- G-treated cultures but not the acute ones. The expression levels of genes encoding products for cell division (FtsW, FtsY) and outer membrane protein E encoding gene (CPSIT_0042) were downregulated (p < 0.05) from 6 h post-infection onward in the persistent infection cultures. Also from 6 h post-infection, the expression levels of DnaA, DnaK, IncC, RpsD, GrpE, and CPSIT_0846 were upregulated (p < 0.05); however, the expression level of OmcB in the persistent infection was almost the same as that in the acute infection (p > 0.05). These results provide new insight regarding molecular activities that accompany persistence of C. psittaci, which may play important roles in the pathogenesis of C. psittaci infection.

Polarization-Independent Metamaterial Analog of Electromagnetically Induced Transparency for a Refractive-Index-Based Sensor

Fan-Yi Meng,Qun Wu,Erni, D.,Ke Wu,Jong-Chul Lee IEEE 2012 IEEE transactions on microwave theory and techniqu Vol.60 No.10

<P>A polarization-independent metamaterial analog of electromagnetically induced transparency (EIT) at microwave frequencies for normal incidence and linearly polarized waves is experimentally and numerically demonstrated. The metamaterial consists of coupled “bright” split-ring resonators (SRRs) and “dark” spiral resonators (SRs) with virtually equal resonance frequencies. Normally incident plane waves with linear polarization strongly couple to the SRR, but are weakly interacting with the SR, regardless of the polarization state. A sharp transmission peak (i.e., the transparency window) with narrow spectral width and slow wave property is observed for the metamaterial at the resonant frequency of both, the bright SRR and the dark SR. The influence of the coupling strength between the SRR and SR on the frequency, width, magnitude, and quality factor of the metamaterial's transparency window is theoretically predicted by a two-particle model, and numerically validated using full-wave electromagnetic simulation. In addition, it is numerically demonstrated that the EIT-like metamaterial can be employed as a refractive-index-based sensor with a sensitivity of 77.25 mm/RIU, which means that the resonance wavelength of the sensor shifts 77.25 mm per unit change of refractive index of the surrounding medium.</P>

The compression-shear properties of small-size seismic isolation rubber bearings for bridges

Wu, Yi-feng,Wang, Hao,Sha, Ben,Zhang, Rui-jun,Li, Ai-qun Techno-Press 2018 Structural monitoring and maintenance Vol.5 No.1

Taking three types of bridge bearings with diameter being 100 mm as examples, the theoretical analysis, the experimental research as well as the numerical simulation of these bearings is conducted. Since the normal compression and shear machines cannot be applied to the small-size bearings, an improved equipment to test the properties of these bearings is proposed and fabricated. Besides, the simulation of the bearings is conducted based on the explicit finite element software ANSYS/LS-DYNA, and some parameters of the bearings are modified in the finite element model to reduce the computation cost effectively. Results show that all the research methods are capable of revealing the fundamental properties of the small-size bearings, and a combined use of these methods can better catch both the integral properties and the inner detailed mechanical behaviors of the bearings.