A Slope One and Clustering based Collaborative Filtering Algorithm

An Gong,Yun Gao,Zhen Gao,Wenjuan Gong,Huayu Li,Hongfu Gao 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.4

Comparative Analysis of Operational Efficiency of Major Airlines in Asia-Pacific Region

Zhen Gong,Tae Seung Kim 인하대학교 정석물류통상연구원 2015 JOURNAL OF INTERNATIONAL LOGISTICS AND TRADE Vol.13 No.1

This paper uses various Data Envelopment Analysis (SBM-DEA) approaches to study the efficiency of major airlines in Asia-Pacific region. To evaluate the operation efficiency of fourteen major airlines in Asia-Pacific region from 2003-2011, Available Seat Kilometers(ASK), Available Ton Kilometers(ATK), the number of employees are used as input factors, Revenue Passenger Kilometers(RPK), Revenue Ton Kilometers(RTK), the amount of Sales are used as output factors. The non-radial SBM-DEA (Slacks-based Measure of Efficiency) model was able to provide a more comprehensive efficiency of combining economic performance and regional difference. And it was also able to capture slack values in input excess and output shortage. The results demonstrate that Korea and Japan airlines are operated efficiently and could be regarded as the benchmarking airlines. On the other hand, most of the China and ASEAN airlines are deemed to be inefficient. Also analyzing slacks may be more suitable way for the evaluation or suggestion of an improvement scheme for the inefficient airlines. The excess of labor is the major cause of the airlines’ inefficiency.

Investigation of the behavior of a crack between two half-planes of functionally graded materials by using the Schmidt method

Zhen-Gong Zhou,Biao Wang,Lin-Zhi Wu 국제구조공학회 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.19 No.4

In this paper, the behavior of a crack between two half-planes of functionally graded materials subjected to arbitrary tractions is resolved using a somewhat different approach, named the Schmidt method. To make the analysis tractable, it is assumed that the Poisson’s ratios of the mediums are constants and the shear modulus vary exponentially with coordinate parallel to the crack. By use of the Fourier transform, the problem can be solved with the help of two pairs of dual integral equations in which the unknown variables are the jumps of the displacements across the crack surfaces. To solve the dual integral equations, the jumps of the displacements across the crack surfaces are expanded in a series of Jacobi polynomials. This process is quite different from those adopted in previous works. Numerical examples are provided to show the effect of the crack length and the parameters describing the functionally graded materials upon the stress intensity factor of the crack. It can be shown that the results of the present paper are the same as ones of the same problem that was solved by the singular integral equation method. As a special case, when the material properties are not continuous through the crack line, an approximate solution of the interface crack problem is also given under the assumption that the effect of the crack surface interference very near the crack tips is negligible. It is found that the stress singularities of the present interface crack solution are the same as ones of the ordinary crack in homogenous materials.

Two collinear Mode-I cracks in piezoelectric/piezomagnetic materials

Zhen-Gong Zhou,Jia-Zhi Wang,Lin-Zhi Wu 국제구조공학회 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.29 No.1

In this paper, the behavior of two collinear Mode-I cracks in piezoelectric/piezomagnetic materials subjected to a uniform tension loading was investigated by the generalized Almansi’s theorem. Through the Fourier transform, the problem can be solved with the help of two pairs of triple integral equations, in which the unknown variables were the jumps of displacements across the crack surfaces. To solve the triple integral equations, the jumps of displacements across the crack surfaces were directly expanded as a series of Jacobi polynomials to obtain the relations among the electric displacement intensity factors, the magnetic flux intensity factors and the stress intensity factors at the crack tips. The interaction of two collinear cracks was also discussed in the present paper.

Two collinear Mode-I cracks in piezoelectric/piezomagnetic materials

Zhou, Zhen-Gong,Wang, Jia-Zhi,Wu, Lin-Zhi Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.29 No.1

In this paper, the behavior of two collinear Mode-I cracks in piezoelectric/piezomagnetic materials subjected to a uniform tension loading was investigated by the generalized Almansi's theorem. Through the Fourier transform, the problem can be solved with the help of two pairs of triple integral equations, in which the unknown variables were the jumps of displacements across the crack surfaces. To solve the triple integral equations, the jumps of displacements across the crack surfaces were directly expanded as a series of Jacobi polynomials to obtain the relations among the electric displacement intensity factors, the magnetic flux intensity factors and the stress intensity factors at the crack tips. The interaction of two collinear cracks was also discussed in the present paper.

The nonlocal theory solution for two collinear cracks in functionally graded materials subjected to the harmonic elastic anti-plane shear waves

Zhou, Zhen-Gong,Wang, Biao Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.23 No.1

In this paper, the scattering of harmonic elastic anti-plane shear waves by two collinear cracks in functionally graded materials is investigated by means of nonlocal theory. The traditional concepts of the non-local theory are extended to solve the fracture problem of functionally graded materials. To overcome the mathematical difficulties, a one-dimensional non-local kernel is used instead of a two-dimensional one for the anti-plane dynamic problem to obtain the stress field near the crack tips. To make the analysis tractable, it is assumed that the shear modulus and the material density vary exponentially with coordinate vertical to the crack. By use of the Fourier transform, the problem can be solved with the help of a pair of triple integral equations, in which the unknown variable is the displacement on the crack surfaces. To solve the triple integral equations, the displacement on the crack surfaces is expanded in a series of Jacobi polynomials. Unlike the classical elasticity solutions, it is found that no stress singularities are present at crack tips.

Investigation of the behavior of a crack between two half-planes of functionally graded materials by using the Schmidt method

Zhou, Zhen-Gong,Wang, Biao,Wu, Lin-Zhi Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.19 No.4

In this paper, the behavior of a crack between two half-planes of functionally graded materials subjected to arbitrary tractions is resolved using a somewhat different approach, named the Schmidt method. To make the analysis tractable, it is assumed that the Poisson's ratios of the mediums are constants and the shear modulus vary exponentially with coordinate parallel to the crack. By use of the Fourier transform, the problem can be solved with the help of two pairs of dual integral equations in which the unknown variables are the jumps of the displacements across the crack surfaces. To solve the dual integral equations, the jumps of the displacements across the crack surfaces are expanded in a series of Jacobi polynomials. This process is quite different from those adopted in previous works. Numerical examples are provided to show the effect of the crack length and the parameters describing the functionally graded materials upon the stress intensity factor of the crack. It can be shown that the results of the present paper are the same as ones of the same problem that was solved by the singular integral equation method. As a special case, when the material properties are not continuous through the crack line, an approximate solution of the interface crack problem is also given under the assumption that the effect of the crack surface interference very near the crack tips is negligible. It is found that the stress singularities of the present interface crack solution are the same as ones of the ordinary crack in homogenous materials.

Intraoperative inspection alone is a reliable guide to the choice of surgical procedure for enteroenteric fistulas in Crohn’s disease

( Zhen Guo ),( Xingchen Cai ),( Ruiqing Liu ),( Jianfeng Gong ),( Yi Li ),( Lei Cao ),( Weiming Zhu ) 대한장연구학회 2018 Intestinal Research Vol.16 No.2

Background/Aims: Resection of the diseased segment and suture of the victim segment is recommended for enteroenteric fistula in Crohn’s disease (CD). The main difficulty in this procedure remains reliable diagnosis of the victim segment, especially for fistulas found intraoperatively and inaccessible on endoscopic examination. We aimed to explore whether intraoperative inspection alone is reliable. Methods: Patients undergoing conservative surgery between 2011 and 2016 for enteroenteric fistulas complicating CD were identified from a prospectively maintained database. Patients were divided according to whether the victim segment was evaluated by preoperative endoscopy + intraoperative inspection (PI group) or by intraoperative inspection alone (I group). Outcomes were compared. Results: Of 65 patients eligible for the study, 37 were in in the PI group and 28 were in the I group. The baseline characteristics were similar between the groups, except for the rate of emergency surgery (0/37 in PI group vs. 5/28 in I group, P=0.012). Fistulas involved more small intestines (4/37 in PI group vs. 15/28 in I group, P< 0.001) and fewer sigmoid colons (17/37 in PI group vs. 4/28 in I group, P=0.008) in I group due to accessibility with endoscopy. No difference was found in postoperative complications, stoma rates, postoperative recurrence, or disease at the repair site between the 2 groups (P >0.05). Conclusions: For fistulas found intraoperatively and inaccessible on endoscopic examination, intraoperative inspection was a reliable guide when choosing between en bloc resection and a conservative procedure. (Intest Res 2018;16:282-287)

Comprehensive evaluation of high-temperature sintering behavior of sea sand vanadia-titania magnetite based on grey relational analysis

Zhen-xing Xing,Zhuang Huang,Gong-jin Cheng,He Yang,Xiangxin Xue,Guo-dong Zhang 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.12

Sea sand vanadia-titania magnetite is difficult to pelletize, and it is difficult for iron and steel enterprises touse it as a raw material for ironmaking. In this paper, the high-temperature physicochemical characteristics and sinteringbehavior of sea sand vanadia-titania magnetite were comprehensively studied and systematically evaluated. Thehigh-temperature metallurgical physicochemical characteristics of different iron ore powders and under different experimentalconditions were studied by the micro-sintering experimental system. The high-temperature sintering indexeswere comprehensively evaluated by the grey correlation analysis, and the influence of sea sand ore on sintering performancewas investigated by sintering pot experiment. The research results show that the high-temperature sinteringcharacteristics of sea sand vanadia-titania magnetite were the worst, and the grey correlation degree was the lowest. The high-temperature sintering characteristics of sintered blocks with sea sand ore were affected by changing the basicityand the addition amount of sea sand ore. When the basicity was 0.8 and the addition amount of sea sand ore was15 wt%, the evaluation index of grey relational analysis was the best. The vertical sintering speed and tumble indexwere slightly reduced by adding sea sand ore, but the sinter yield was improved and the particle size distribution of sinterwas optimized. The experimental results provide a certain data reference for the actual production of sinter with seasand vanadia-titania magnetite.

Does matching relation exist between the length and the tilting angle of terminal implants in the all-on-four protocol? stress distributions by 3D finite element analysis

Zhen Tang,Lulu Gong,Dalin Wang,Xiaoqian Qiu,Zhizhong Cao,Xiaomei Li 대한치과보철학회 2015 The Journal of Advanced Prosthodontics Vol.7 No.3

PURPOSE To explore whether there is matching relation between the length and the tilting angle of terminal implants in the All-on-Four protocol by studying the effects of different implant configurations on stress distributions of implant, bone, and framework. MATERIALS AND METHODS Four implants were employed to support a full-arch fixed prosthesis and five three-dimensional finite element models were established with CT images, based on the length (S and L) and distal tilt angle (0°, 30° and 45°) of terminal implants for an edentulous mandible, which named: Tilt0-S, Tilt30-S, Tilt30-L, Tilt45-S and Tilt45-L. An oblique 240 N was loaded at second molar. The von Mises Stresses were analyzed. The implants were consecutively named #1 to #4 from the loading point. RESULTS 1) Tilt0-S had the greatest stress on the implants, with the other groups exhibiting variable reductions; the four implants of Tilt45-L demonstrated the greatest reduction in stress. 2) Tilt0-S had the greatest stress at bone around #1 implant neck, and Tilt45-L exhibited the least stress, which was a 36.3% reduction compared to Tilt0-S. 3) The greatest stress in the framework was found on the cantilevers distal to #1 implant. Tilt45-S exhibited the least stress. CONCLUSION Matching different length and tilting angle of the terminal implants led to variable stress reductions on implants, bone and the superstructure. By optimizing implant configuration, the reduction of stress on implants and surrounding bone could be maximized. Under the present condition, Tilt45-L was the preferred configuration. Further clinical testings are required.