ON THE (n, d)^th f-IDEALS

GUO, JIN,WU, TONGSUO Korean Mathematical Society 2015 대한수학회지 Vol.52 No.4

For a field K, a square-free monomial ideal I of K[$x_1$, . . ., $x_n$] is called an f-ideal, if both its facet complex and Stanley-Reisner complex have the same f-vector. Furthermore, for an f-ideal I, if all monomials in the minimal generating set G(I) have the same degree d, then I is called an $(n, d)^{th}$ f-ideal. In this paper, we prove the existence of $(n, d)^{th}$ f-ideal for $d{\geq}2$ and $n{\geq}d+2$, and we also give some algorithms to construct $(n, d)^{th}$ f-ideals.

STRONG SHELLABILITY OF SIMPLICIAL COMPLEXES

Guo, Jin,Shen, Yi-Huang,Wu, Tongsuo Korean Mathematical Society 2019 대한수학회지 Vol.56 No.6

Imposing a strong condition on the linear order of shellable complexes, we introduce strong shellability. Basic properties, including the existence of dimension-decreasing strong shelling orders, are developed with respect to nonpure strongly shellable complexes. Meanwhile, pure strongly shellable complexes can be characterized by the corresponding codimension one graphs. In addition, we show that the facet ideals of pure strongly shellable complexes have linear quotients.

ON RINGS WHOSE ANNIHILATING-IDEAL GRAPHS ARE BLOW-UPS OF A CLASS OF BOOLEAN GRAPHS

Guo, Jin,Wu, Tongsuo,Yu, Houyi Korean Mathematical Society 2017 대한수학회지 Vol.54 No.3

For a finite or an infinite set X, let $2^X$ be the power set of X. A class of simple graph, called strong Boolean graph, is defined on the vertex set $2^X{\setminus}\{X,{\emptyset}\}$, with M adjacent to N if $M{\cap}N={\emptyset}$. In this paper, we characterize the annihilating-ideal graphs $\mathbb{AG}(R)$ that are blow-ups of strong Boolean graphs, complemented graphs and preatomic graphs respectively. In particular, for a commutative ring R such that AG(R) has a maximum clique S with $3{\leq}{\mid}V(S){\mid}{\leq}{\infty}$, we prove that $\mathbb{AG}(R)$ is a blow-up of a strong Boolean graph if and only if it is a complemented graph, if and only if R is a reduced ring. If assume further that R is decomposable, then we prove that $\mathbb{AG}(R)$ is a blow-up of a strong Boolean graph if and only if it is a blow-up of a pre-atomic graph. We also study the clique number and chromatic number of the graph $\mathbb{AG}(R)$.

Gastroprotective effect of cirsilineol against hydrochloric acid/ethanol-induced gastric ulcer in rats

Guojin Gong,Rigetu Zhao,Yuhui Zhu,Jinfeng Yu,Bin Wei,Yan Xu,Zhaoxun Cui,Guoying Liang 대한생리학회-대한약리학회 2021 The Korean Journal of Physiology & Pharmacology Vol.25 No.5

This study was designed to evaluate the gastroprotective activity of cirsilineol in hydrochloric acid (HCl)/ethanol-induced gastric ulcer model. Cirsilineol was administered at the doses of 20 and 40 mg/kg in HCl/ethanol-induced rats. The gastroprotective ability was verified by determining the ulcer score, total acidity, hemoglobin, inflammatory cytokines, lipid peroxides, and enzymatic antioxidants superoxide dismutase (SOD) and catalase (CAT) in gastric tissue and serum biochemical analysis. The results showed a favorable increase in the hemoglobin level, antioxidant enzymes (SOD and CAT), restored electrochemical balance (carbon dioxide & anion gap) while a noticeable decrease in ulcer index, total acidity, lipid peroxides, inflammatory cytokines (interleukin-1 beta [IL-1β], IL-6, and tumor necrosis factor alpha) in rats treated with the cirsilineol. The serum biochemical analysis on liver markers (alkaline phosphatases, alanine aminotransferase, and aspartate aminotransferase), kidney markers (urea, creatinine, albumin, globulin, total protein), and lipid profile (triglyceride, high-density lipoprotein, total cholesterol) were attenuated by cirsilineol treatment in rats. Histopathology showed enhanced gastric protection and preserved the integrity of gastric mucosa upon cirsilineol administration. These results ultimately suggest that cirsilineol has gastroprotective effects that prevent the development of gastric ulcer.

한국산 잇바디돌김 (Porphyra dentata)의 핵 18S rDNA 염기서열 분석

Long-GuoJin,김명숙,조지영,진형주,홍용기 한국생명과학회 2002 생명과학회지 Vol.12 No.4

Nuclear 18S ribosomal RNA gene (18S rDNA or SSU rDNA) from the Porphyra dentata tissue was amplified and sequenced. Complete 18S rDNA has an 1822 bp exon and a 512 bp intron. The G+C contents of exon and intron were 49% and 55%, respectively. The exon sequence showed 97.1% homology to the GenBank accession number AB013183 of the Japanese P. dentata. The intron region that is inserted in upstream between 568 and 569 showed 52.1% homology to the AB013183.Key words - 18S rDNA, Porphyra dentata, seaweed, sequence analysis 잇바디돌김(Porphyra dentata)을 대상으로 핵의 18S ribosomal RNA를 지령하는 유전자 즉 18S rDNA 유전자를 증폭하고, 염기서열분석을 수행하였다. 전체 18S rDNA의 exon 영역 크기는 1822 bp, intron 영역의 크기는 512 bp였다. 이들 exon과 intron 영역의 G+C 함량은 각각 49%와 55%씩 나타내었다. 일본산 잇바디돌김(GenBank accession number: AB013183)의 exon 영역과의 비교에서 상동성이 97.1%에 도달하였다. 568번과 569번 염기사이의 upstream에 위치하는 intron 영역에서는 AB013183과 52.1%의 상동성을 보였다.

Free vibration analysis of cracked Timoshenko beams carrying spring-mass systems

Tan, Guojin,Shan, Jinghui,Wu, Chunli,Wang, Wensheng Techno-Press 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.4

In this paper, an analytical approach is proposed for determining vibration characteristics of cracked non-uniform continuous Timoshenko beam carrying an arbitrary number of spring-mass systems. This method is based on the Timoshenko beam theory, transfer matrix method and numerical assembly method to obtain natural frequencies and mode shapes. Firstly, the beam is considered to be divided into several segments by spring-mass systems and support points, and four undetermined coefficients of vibration modal function are contained in each sub-segment. The undetermined coefficient matrices at spring-mass systems and pinned supports are obtained by using equilibrium and continuity conditions. Then, the overall matrix of undetermined coefficients for the whole vibration system is obtained by the numerical assembly technique. The natural frequencies and mode shapes of a cracked non-uniform continuous Timoshenko beam carrying an arbitrary number of spring-mass systems are obtained from the overall matrix combined with half-interval method and Runge-Kutta method. Finally, two numerical examples are used to verify the validity and reliability of this method, and the effects of cracks on the transverse vibration mode shapes and the rotational mode shapes are compared. The influences of the crack location, depth, position of spring-mass system and other parameters on natural frequencies of non-uniform continuous Timoshenko beam are discussed.

Life Prediction of Residual Current Circuit Breaker with Overcurrent Protection Based on BP Neural Network Optimized by Genetic Algorithm

Liu Guojin,Miao Jianhua,Zhao Xingzhou,Wang Ze,Li Xiang 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.3

The service life of the residual current circuit breaker with overcurrent protection (RCBO) is long and its life information is diffi cult to obtain. In order to predict its life, a life prediction method based on RCBO performance degradation data is presented in this paper. Firstly, the residual operating current is determined as the degradation evaluation quantity of RCBO. An accelerated degradation test with temperature as the acceleration stress is carried out, and the performance degradation data are obtained. Secondly, the Optimized BP neural network (BPNN) model based on test degradation data is established. The genetic algorithm is used to optimize the BPNN model, which prevents the model from falling into the local optimal solution and improves the prediction accuracy. Thirdly, the pseudo failure life of RCBO under various stresses is predicted by the optimized model. After the test, the relative error between the predicted life and the true value is less than 10%, which meets the requirements of engineering applications. Finally, the service life of RCBO at normal temperature (25 °C) is deduced by the Arrhenius equation.

Adaptive active damping method of grid‑connected inverter based on model predictive control in weak grid

Ruinan Xue,Guojin Li,Hengzhou Tong,Yanming Chen 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.7

The LCL-type grid-connected inverter based on finite control set model predictive control (FCS-MPC) is suitable for weak grids because of its good robustness and fast dynamic response. However, in an FCS-MPC-based system, the variable switching frequency causes the spread of the inverter-side current harmonic spectrum. Thus, the grid-side current may be distorted because the harmonics are amplified to the grid side due to the resonance peak of the LCL filter. To solve the above problem, this paper proposes an adaptive active damping (AD) method to eliminate the resonant effects. First, the system based on an MPC controller is regarded as a closed-loop system of the grid-side current, and the resonance peak is suppressed effectively by an AD, which consists of a virtual resistor and a virtual capacitor. Second, to balance the resonance suppression and dynamic performance of the system under weak grid conditions, the grid impedance is measured and the optimal AD values for different grid impedance are calculated online. Compared with the fixed-value AD, the proposed method has better resonance suppression and higher bandwidth. The effectiveness and feasibility of the proposed control strategy are verified by simulations and experiments.

Approximating Bézier Curves by Cubic Bézier Curves with a Linear Field of Normal Vectors

Weixian Huang,Congjian Jin,Guojin Wang (사)한국CDE학회 2010 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8

In order to derive the offset curves by using cubic Bezier curves with a linear field of normal vectors (the so-called LN Bezier curves) more efficiently, three methods for approximating degree n Bezier curves by cubic LN Bezier curves are presented. The approximation based on shifting control points is equivalent to solving a quadratic equation, and the approximation based on L₂ norm is equivalent to solving a quartic equation. In addition, the sufficient and necessary condition of optimal approximation based on Hausdorff distance is presented, accordingly the algorithm for approximating the degree n Bezier curves based on Hausdorff distance is derived. Numerical examples show that the error of approximation based on Hausdorff distance is much smaller than that of approximation based on shifting control points and L₂ norm, furthermore, the algorithm based on Hausdorff distance in much simple and convenient.

Interaction and Treatment for Tunnels Orthogonally Traversing Large Bedrock Landslides

Changan Zhu,Feng Yang,Jinlong Zheng,Guojin Lin,Zhiyu Tian 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.7

When a tunnel orthogonally traverses a large bedrock landslide, the interaction between the tunnel and the bedrock can easily disturb the stability of the slope and deformation of tunnel structures. In this work, Jimei tunnel in southwest China was studied as an example. The physical parameters of the landslide were inverted based on uniform design and a radial basis function neural network model and a model was established for the interaction of tunnel and bedrock landslide. Simulations showed that tunnel construction resulted in tensile failure at the trailing edge of bedrock landslide and clear deformation in the left line of the tunnel. This was consistent with the field damage observed in this work. A comparative analysis was performed of structural stability after the application of three schemes of earth-rock clearing, load-reducing, and slide-resistant pile arrangements. Optimal measures for landslide reinforcement were determined to ensure smooth tunnel construction and reduce project cost. Two years of continuous post-construction monitoring indicated that the stability of tunnel and landslide was preserved and treatment goal was achieved. Calculation methods and control measures developed in the current research for tunnels orthogonally traversing bedrock landslides provided a useful reference for similar projects in the future.