THE CLASS OF MODULES WITH PROJECTIVE COVER

Guo, Yong-Hua Korean Mathematical Society 2009 대한수학회지 Vol.46 No.1

Let R be a ring. A right R-module M is called perfect if M possesses a projective cover. In this paper, we consider the relationship between the class of perfect modules and other classes of modules. Some known rings are characterized by these relationships.

Optimal Waveform Design for Ultra-Wideband Communication Based on Gaussian Derivatives

Guo, Yong The Korea Institute of Information and Commucation 2008 Journal of communications and networks Vol.10 No.4

Ultra-wideband (UWB) radios have attracted great interest for their potential application in short-range high-data-rate wireless communications. High received signal to noise ratio and compliance with the Federal Communications Commissions (FCC) spectral mask call for judicious design of UWB pulse shapers. In this paper, even and odd order derivatives of Gaussian pulse are used respectively as base waveforms to produce two synthesized pulses. Our method can realize high efficiency of spectral utilization in terms of normalized effective signal power (NESP). The waveform design problem can be converted into linear programming problem, which can be efficiently solved. The waveform based on even order derivatives is orthogonal to the one based on odd order derivatives.

Quaternion-based Finite-time Control for Attitude Tracking of the Spacecraft without Unwinding

Yong Guo,Shen-Min Song,Xue-Hui Li 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.6

This paper investigates two finite-time controllers for the attitude tracking control of the spacecraft based on the quaternion by terminal sliding mode control. Because quaternion is unable to represent the set of attitudes both globally and uniquely, it can result in unwinding. Unwinding makes a spacecraft perform an unnecessary large-angle maneuver when a small-angle maneuver in the opposite rotational direction is sufficient to achieve the objective. The first controller converges to the equilibrium without singularity in finite time, while the second one converges to the region near the equilibrium without singularity, chattering and unwinding in finite time. Saturation function is introduced to the first controller to eliminate singularity, while a novel fast terminal sliding mode control is introduced to the second controller to eliminate singularity and unwinding. Theoretical analysis shows that the controllers can make the spacecraft follow a time-varying reference attitude signal in finite time and guarantee the stability of the overall closed-loop system. Numerical simulations also demonstrate the effectiveness of the proposed control schemes.

Association Between C-reactive Protein and Risk of Cancer: A Meta-analysis of Prospective Cohort Studies

Guo, Yong-Zhong,Pan, Lei,Du, Chang-Jun,Ren, Dun-Qiang,Xie, Xiao-Mei Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.1

Background: Associations between elevated C-reactive protein (CRP) and cancer risk have been reported for many years, but the results from prospective cohort studies remains controversial. A meta-analysis of prospective cohort studies was therefore conducted to address this issue. Methods: Eligible studies were identified by searching the PubMed and EMBASE up to October 2012. Pooled hazard ratios (HR) was calculated by using random effects model. Results: Eleven prospective cohort studies involving a total of 194,796 participants and 11,459 cancer cases were included in this meta-analysis. The pooled HR per natural log unit change in CRP was 1.105 (95% confidence interval (CI): 1.033-1.178) for all-cancer, 1.308 (95% CI: 1.097-1.519) for lung cancer, 1.040 (95% CI: 0.910-1.170) for breast cancer, 1.063 (95% CI: 0.965-1.161) for prostate cancer, and 1.055 (95% CI: 0.925-1.184) for colorectal cancer. Dose-response analysis showed that the exponentiated linear trend for a change of one natural log unit in CRP was 1.012 (95% CI: 1.006-1.018) for all-cancer. No evidence of publication bias was observed. Conclusions: The results of this meta-analysis showed that the elevated levels of CRP are associated with an increased risk of all-cancer, lung cancer, and possibly breast, prostate and colorectal cancer. The result supports a role of chronic inflammation in carcinogenesis. Further research effort should be performed to identify whether CRP, as a marker of inflammation, has a direct role in carcinogenesis.

The effect of cyfluthrin on testis inhibin B in rats and the intervention of Lycium barbarum polysaccharide

Guo Xin,Xie Yong-Xin,Guo Chen,Wei Jing-Lin,Yang Hui-Fang 대한독성 유전단백체 학회 2021 Molecular & cellular toxicology Vol.17 No.2

Background In recent years, studies have shown that cyfluthrin is harmful to the reproductive system. Lycium barbarum polysaccharide may be a protective agent. Objective To investigate the effect of cyfluthrin (Cy) on testosterone B (inhibin B, INHB) in male rats and the intervention of Lycium barbarum polysaccharide (LBP). Results Compared with the control group, the mRNA and protein expression levels of INH α and INH βB in the testis tissue decreased, and the difference was statistically significant (P < 0.05). The LBP intervention group can significantly increase the expression level, and the difference is statistically significant (P < 0.05). Conclusion The decrease of INHα and INHβB expression caused by Cy exposure indicates that Cy has a toxic effect on the testis of rats, and the addition of LBP has a certain protective effect on the testis of rats. Background In recent years, studies have shown that cyfluthrin is harmful to the reproductive system. Lycium barbarum polysaccharide may be a protective agent. Objective To investigate the effect of cyfluthrin (Cy) on testosterone B (inhibin B, INHB) in male rats and the intervention of Lycium barbarum polysaccharide (LBP). Results Compared with the control group, the mRNA and protein expression levels of INH α and INH βB in the testis tissue decreased, and the difference was statistically significant (P < 0.05). The LBP intervention group can significantly increase the expression level, and the difference is statistically significant (P < 0.05). Conclusion The decrease of INHα and INHβB expression caused by Cy exposure indicates that Cy has a toxic effect on the testis of rats, and the addition of LBP has a certain protective effect on the testis of rats.

The elastoplastic formulation of polygonal element method based on triangular finite meshes

Yong-chang Cai,He-hua Zhu,Sheng-yong Guo 국제구조공학회 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.30 No.1

A small strain and elastoplastic formulation of Polygonal Element Method (PEM) is developed for efficient analysis of elastoplastic solids. In this work, the polygonal elements are constructed based on traditional triangular finite meshes. The construction method of polygonal mesh can directly utilize the sophisticated triangularization algorithm and reduce the difficulty in generating polygonal elements. The Wachspress rational finite element basis function is used to construct the approximations of polygonal elements. The incremental variational form and a von Mises type model are used for non-linear elastoplastic analysis. Several small strain elastoplastic numerical examples are presented to verify the advantages and the accuracy of the numerical formulation.

Impact performance for high frequency hydraulic rock drill drifter with sleeve valve

Guo, Yong,Yang, Shu Yi,Liu, De Shun,Zhang, Long Yan,Chen, Jian Wen Korean Society for Fluid machinery 2016 International journal of fluid machinery and syste Vol.9 No.1

A high frequency hydraulic rock drill drifter with sleeve valve is developed to use on arm of excavator. In order to ensure optimal working parameters of impact system for the new hydraulic rock drill drifter controlled by sleeve valve, the performance test system is built using the arm and the hydraulic source of excavator. The evaluation indexes are gained through measurement of working pressure, supply oil flow and stress wave. The relations of working parameters to impact system performance are analyzed. The result demonstrates that the maximum impact energy of the drill drifter is 98.34J with impact frequency of 71HZ. Optimal pressure of YZ45 rock drill is 12.8 MPa-13.6MPa, in which the energy efficiency reaches above 58.6%, and feature moment of energy distribution is more than 0.650.

Robust Design of Main Control Valve for Hydraulic Pile Hammer Flexible Control System

Guo, Yong,Hu, Jun Ping,Zhang, Long Yan Korean Society for Fluid machinery 2016 International journal of fluid machinery and syste Vol.9 No.1

The flexible control system for hydraulic pile hammer using main control valve is present to the requirement of rapidly reversing with high frequency. To ensure the working reliability of hydraulic pile hammer, the reversing performance of the main control valve should commutate robustness to various interfere factors. Through simulation model built in Simulink/Stateflow and experiment, the effects of relative parameters to reverse performance of main control are analyzed and the main interfere factors for reversing performance are acquired. Treating reverse required time as design objects, some structure parameters as control factors, control pressure, input flow and gaps between spool and valve body as interfere factors, the robust design of the main control valve is done. The combination of factors with the strongest anti-jamming capability is acquired which ensured the reliability and anti-jamming capability of the main control valve. It also provides guidance on design and application of the main control valve used in large flow control with interferes.

Site-directed Mutagenesis of the Toxin from the Chinese Scorpion Buthus martensii Karsch (BmKAS): Insight into Sites Related to Analgesic Activity

Yong Cui,Yong-Bo Song,Lin Ma,Yan-Feng Liu,Guo-Dong Li,Chun-Fu Wu,Jing-Hai Zhang 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.10

This study utilized the E. coli expression system to investigate the role of amino acid residues in toxin from the Chinese scorpion - Buthus martensii Karsch (BmKAS). To evaluate the extent to which residues of the toxin core contribute to its analgesic activity, ten mutants of BmKAS were obtained by PCR. Using site-directed mutagenesis, all of these residues were substituted with different amino acids. This study represents a thorough mapping and elucidation of the epitopes that form the molecular basis of the toxin’s analgesic activity. Our results showed large mutant-dependent differences that emphasize the important roles of the studied residues.

Core/Shell Molecular Imprinting Microparticles Prepared Using RAFT Technology for Degradation of Paraoxon

Yong Guo,Tian Ying Guo,Ying Yang,Lei Zhang 한국고분자학회 2011 Macromolecular Research Vol.19 No.11

We have developed a uniform core-shell structured surface hydrogel imprinted molecular imprinting polymer (MIP). This was achieved by surface grafting on a disulfide ester modified polystyrene core, using reversible addition-fragmentation transfer polymerization (RAFT) with N-methacryloyl-histidine-Cu2^+ complex (MAHCu ^2+) as the functional monomer and methyl paraoxon as the template to simulate phosphotriesterase (PTE). Subsequently,we investigated the catalytic (hydrolytic) activities of MIP to the template methyl paraoxon and the template analogue ethyl paraoxon. The results showed that the catalytic (hydrolytic) activity of MIP to the template methyl paraoxon was the highest, and the value of k was 8.67×10^-5 mM·L^-1·min^-1, which was 3.89-fold higher than MIP to ethyl paraoxon and 2.79-fold higher than the non-imprinting polymer (NIP) to methyl paraoxon. The K_m and r_m of MIP were also determined: the K_m was 3.95×10-4 M and the r_m 2.12 μM/min. The MIP can be reused with only lose 7% of catalytic activity for four cycles.