• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2020-2028
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• 2013

In this paper, we propose a novel analysis and design methodology based on complex network theory for wireless large-scale ad hoc networks. We also enhance the conventional analysis methods which does not sufficiently consider the effect of the wireless communication channels and extend the existing random graph theory by reflecting the wireless communication environments. As a main result, the effect of the network topology such as average degree of each communication node on the network capacity through extensive computer simulations.

• Journal of the Korean Mathematical Society
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• v.55 no.3
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• pp.623-669
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• 2018

In Donaldson-Thomas theory, moduli spaces are locally the critical locus of a holomorphic function defined on a complex manifold. In this paper, we develop a theory of critical virtual manifolds which are the gluing of critical loci of holomorphic functions. We show that a critical virtual manifold X admits a natural semi-perfect obstruction theory and a virtual fundamental class $[X]^{vir}$ whose degree $DT(X)=deg[X]^{vir}$ is the Euler characteristic ${\chi}_{\nu}$(X) weighted by the Behrend function ${\nu}$. We prove that when the critical virtual manifold is orientable, the local perverse sheaves of vanishing cycles glue to a perverse sheaf P whose hypercohomology has Euler characteristic equal to the Donaldson-Thomas type invariant DT(X). In the companion paper, we proved that a moduli space X of simple sheaves on a Calabi-Yau 3-fold Y is a critical virtual manifold whose perverse sheaf categorifies the Donaldson-Thomas invariant of Y and also gives us a mathematical theory of Gopakumar-Vafa invariants.

• Journal of the Korean Home Economics Association
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• v.41 no.3
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• pp.73-91
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• 2003

This research tested the path model which examined the direct and indirect effects of family violence experience on perpetration of dating violence among college students. Two family violence variables such as witnessing parents' marital violence and being abused by parent were the exogeneous variables in the path model, while the mediated variables were consisted of (1) the social-learning-theory-derived variables such as acceptance of violence, positive outcome expectations of using violence, and aggressive conflict-coping behavior, and (2) control-theory-derived variables such as attachment, belief, and commitment. Data were from self-administered questionnaires completed by 332 male and 469 female students selected by stratified quota sampling method. The path analysis was done for males and females separately, since females reported significantly higher degree of dating violence than males. Results of the path analysis showed that first, for both males and females, being abused by parents directly and indirectly influenced dating violence, while witnessing parents' marital violence did not have effect on dating violence either directly or indirectly. Second, for male students, acceptance of violence and conflict coping behavior found to be the mediated variables in the effect of being abused by parents on dating violence. Third, for females, a control-theory-derived variable of belief as well as all three social learning theory-derived variables mediated the influence of being abused by parents on dating violence.

• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.435-449
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• 2020

This work presents the formulation of the isogeometric collocation method to solve the strong form equation of a unified and integrated approach of Reissner Mindlin plate theory (UI-RM). In this plate theory model, the total displacement is expressed in terms of bending and shear displacements. Rotations, curvatures, and shear strains are represented as the first, the second, and the third derivatives of the bending displacement, respectively. The proposed formulation is free from shear locking in the Kirchhoff limit and is equally applicable to thin and thick plates. The displacement field is approximated using the B-splines functions, and the strong form equation of the fourth-order is solved using the collocation approach. The convergence properties and accuracy are demonstrated with square plate problems of thin and thick plates with different boundary conditions. Two approaches are used for convergence tests, e.g., increasing the polynomial degree (NELT = 1×1 with p = 4, 5, 6, 7) and increasing the number of element (NELT = 1×1, 2×2, 3×3, 4×4 with p = 4) with the number of control variable (NCV) is used as a comparable equivalent variable. Compared with DKMQ element of a 64×64 mesh as the reference for all L/h, the problem analysis with isogeometric collocation on UI-RM plate theory exhibits satisfying results.

• International journal of advanced smart convergence
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• v.10 no.3
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• pp.245-256
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• 2021

This study is significant in determining the reduction of safety accidents by applying PDCA's theory by subdividing it into a case analysis technique for construction sites by PDCA's theory. For this study, accidents accounted for the largest proportion of each type of disaster in the construction site were considered, and safety accidents were reduced through the PDCA theory through prior research. The analysis method of this study derived improvement plans by applying PDCA techniques to plan, implement, confirm, review, and improve disaster accidents at construction sites. The conclusions of this study are as follows. In the plan, first of all, measures shall be taken to prepare a safety management plan, to verify the implementation of the plan, and to verify the degree of implementation by the field manager. In the implementation, first of all, it is necessary to introduce a safety education history system to strengthen the safety education curriculum to suit the site, as long-term work is impossible for field workers depending on field conditions. First of all, it is necessary to strengthen the installation of safety facilities, including "work scaffolding" and "conducting prevention facilities" at construction sites. In management review and improvement, the risk assessment system for construction sites needs to be expanded first°.

• Journal of Industrial Technology
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• v.26 no.B
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• pp.83-92
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• 2006

A probabilistic analysis model. one of reliability analysis methods introducing the concept of variables, was developed to investigate the uncertainty of dominant factors influencing the degree of consolidation in the radial consolidation theories. Based on the developed probabilistic analysis model, sensitivity study of those factors was performed to find their trends of affecting the degree of consolidation in the vertical drain method. Various radial consolidation theories, proposed by Barron(1948), Hansbo(1979), Yoshikuni(1979) and Onoue(1988), were used for this parametric study with the influencing factors such as size of smear zone, reduction ratio of permeability in the smear zone, discharge capacity, permeability for horizontal flow and coefficient of consolidation for horizontal flow. As results of this sensitivity study, for the given consolidation theory, contribution of each factor to the degree of consolidation was figure out and compared to each other. For the given value of each factor, the sensitivity to the degree of consolidation in the various theories was evaluated and their applicability and limitations were assessed.

• Journal of Distribution Science
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• v.13 no.3
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• pp.11-19
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• 2015

Purpose - This study examines the strength of sadness and the belief it will last, as regards the effects of the degree of self-extension to the sad-evoking event on choice behavior related to self-control dilemmas. Research Design, Data, and Methodology - In an experiment involving high and low self-extension groups, 261 undergraduates answered self-administered questionnaires. The hypotheses were tested using AMOS 19.0 and path analysis. Results - The positive relationship between the degree of self-extension to the sad-evoking event and hedonic vs. utilitarian food choices was mediated by the belief that the sadness will last. There is a significant indirect path from the degree of self-extension (to the sad-evoking event) to the strength of the sadness, and to the belief that it will last with respect to hedonic vs. utilitarian food choices. Conclusions - These results show that beliefs about sad emotion transience depend on both the degree of self-extension to the sad-evoking event and the strength of sadness, and that the belief that sad emotions are transient makes sad people susceptible to temptation when facing self-control related dilemmas.

• Journal of Power System Engineering
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• v.10 no.1
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• pp.12-18
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• 2006

A three-degree of freedom model of intake system was contrived and investigated in various ways for the purpose of the amelioration of the volumetric efficiency in a low and transient engine speed for a multi cylinder diesel engine. The basic concept beyond this model started from the theory that each degree of freedom model has volumetric efficiency peak as many as its number of the degree of freedom. The volumetric efficiency affects significantly to the engine performance; torque characteristics, fuel economy and emission level. For commercial vehicles and stationary engines, the engine is designed so as to produce their best performance near the normal engine speeds, thus the low engine speed area has a tendency of poor volumetric efficiency. The aim of this study was highlighted on the amelioration of volumetric efficiency of low engine speed area in a multi cylinder diesel engine matched with an additional Helmholtz resonator. By the use of VIS(variable induction system) volumetric efficiency at low engine speed range was significantly improved. The availability of control by combination of VIS and CIS(conventional induction system) will be proposed as a variable induction system that would be an appropriate model for amelioration of the volumetric efficiency at low engine speed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.3 s.73
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• pp.223-231
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• 2006

This study deals with behavior characteristics of laminated composite folded structures according to ratio of folded length based on a higher-order shear deformation theory. Well-known mixed finite element method using Lagrangian and Hermite shape interpolation functions is a little complex and have some difficulties applying to a triangular element. However, a higher-order shear deformation theory using only Lagrangian shape interpolation functions avoids those problems. In this paper, a drilling degree of freedom is appended for more accurate analysis and computational simplicity of folded plates. There are ten degrees of freedom per node, and four nodes per element. Journal on folded plates for effects of length variations is not expressed. Many results in this study are carried out according to ratio of folded length. The rational design is possible through analyses of complex and unpredictable laminated composite folded structures.

• Journal of Korean Society of Transportation
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• v.28 no.4
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• pp.177-186
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• 2010

The principal objective of this paper is to develop road design guidelines, especially for managed lane access spacing between the expressway on-ramp (or off-ramp) and managed lane access point. Managed lanes are typically located in the expressway median and are accessed by weaving across the mainlines. The high level of lane-changing activity present in weaving areas affects capacity significantly. One promising tool for the analysis of lane-changing activity is "gap acceptance theory." This paper estimates the capacity of weaving areas based on the estimated degree of traffic turbulence using gap acceptance theory. The degree of traffic turbulence is represented by a function of the probability that lane-changing vehicles can complete their maneuvers successfully in a given weaving distance. In developing road design guidelines based on the developed gap acceptance model, the minimum managed lane access spacing is determined where the capacity with respect to the managed lane access spacing becomes stable.