• East Asian mathematical journal
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• v.31 no.5
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• pp.743-751
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• 2015

In this paper, we consider a discrete ratio-dependent predator-prey system with harvesting effect. In order to investigate dynamical behaviors of this system, first we find out all fixed points of the system and then classify their stabilities by using their Jacobian matrices and local stability method. Next, we display some numerical examples to substantiate theoretical results and finally, we show numerically, by means of a bifurcation diagram, that various dynamical behaviors including cycles, periodic doubling bifurcation and chaotic bands can be existed.

• East Asian mathematical journal
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• v.30 no.5
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• pp.583-597
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• 2014

In this paper, we study an area-preserving piecewise linear map with the feature of dangerous border collision bifurcations. Using this map, we study dynamical properties occurred in the invariant set, specially related to the boundary of KAM-tori, and the existence and stabilities of periodic orbits. The result shows that elliptic regions having periodic orbits and chaotic region can be divided by smooth curve, which is an unexpected result occurred in area preserving smooth dynamical systems.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.18-25
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• 2001

Analysis of prestressed box-girder bridges using the spline finite strip method is presented. In the present study, the spline finite strip method(FSM) is modified using the non-periodic B-spline interpolation. In the analysis of the prestressed box girder bridges, each tendon force is evaluated by summation of the adjacent segment forces. Once the equivalent forces acting on the structure at the tendon points are found, they are transformed into statically equivalent forces at the adjacent node or joints. Several examples were analyzed to verify the performance of present method using the non-periodic B-spline FSM. Good agreements were obtained when compared with the previous study.

• Nonlinear Functional Analysis and Applications
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• v.26 no.2
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• pp.303-322
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• 2021

The concepts of new classes of mappings are introduced in the spaces which are more general space than the usual metric spaces. The existence and uniqueness of common fixed points and fixed point results are established in the setting of complete complex valued b-metric spaces. An illustration is given by establishing the existence of solution of periodic differential equations in the framework of a complete complex valued b-metric spaces.

• Research in Community and Public Health Nursing
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• v.4 no.2
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• pp.139-145
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• 1993

The purpose of this study was to identify the degree and the relationship of the Knowledge, Attitude and Practice of industrial health care services of workers. This information will provide useful data for an effective industrial health care service. The was collected from 600 data employees in Kwang-ju city & Chonnam province. The data was gathered by questionnaire from Dec 20, 1992 to Jan 20, 1993. The questionnaire was developed by the Academic Affairs of Community Health Nursing Academy. Data was analyzed by using the statistical computer package, SPSS to manipulate the data along with percentages, means, standard deviations, modes, t-test and ANOVA. The results in this study were summarized as follows: 1. General characteristics of workers: Distributions of workers was laborer(76.2%). in the 25-34 age group(50.2%), married(63.3%), males comprised(77.5%), the educational level with the highest percentage was high school graduates (71.1%), with a monthly income of 300-700 thousand won(43.8%), and has been working in the present career over seven years (31.5%). 2. The Knowledge, Attitude and Practice levels of employees about industrial health care services The levels were measured according to a five point scale. The total mean score of knowledge was 2.92 points out of 4. The following are the scores of Knowledge of special medical examination and location of industrial clinic(3.48), periodic medical examination (3.18), occupational disease(3.08), personal protective equipment (2.92), and health education(1.37). The total mean score of Attitude was 2.77 point out of 4. The following are the scores of Attitude in order of working environment (3.35), necessity of periodic medical examination and health education(3.15), the worker's perception influence on the working environment to health was high(3.11). But, the level of satisfaction in the content of periodic medical examination was low(2.19). The total mean score of Practice was 2.70 points out of 4. The scores of Practice in order were, practice of periodic medical examination(3.70), utilization of industrial clinic(2.92), and to participate in health education(1.47). 3. The relationship of general characteristics to Knowledge, Attitude, and Practice of workers: Knowledge had a significant difference by sex (P<.01), marital status(P<.01), education level (P<.05) and monthly income(P<.01). Attitude was significantly different with sex(P<.05) and Practice was significantly related to monthly income (P<.01).

• Journal of the Chungcheong Mathematical Society
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• v.16 no.1
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• pp.113-121
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• 2003

This paper is concerned with some properties of stable domains and limit functions. Using the relationship between cycles of periodic stable domains and orbits of critical points and using the Sullivan theorem [19], we prove that the value of a constant limit function in some stable domain for a rational function f of degree at least two lies in the closure of the set of critical orbits of f.

• Korean Journal of Mathematics
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• v.25 no.2
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• pp.137-145
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• 2017

We consider some simple periodic functions on the field of rational numbers with values in ${\mathbb{Q}}/{\mathbb{Z}}$ which are defined in terms of lowest-term-expression of rational numbers. We prove the density of graphs of these functions by constructing explicitly points on the graphs close to a given point using continued fractions.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1234-1239
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• 1993

We study how to design conventional feedback controllers to drive chaotic trajectories of the well-known systems to their equilibrium points or any of their inherent periodic orbits. The well-known chaotic systems are Heon map and Duffing's equation, which are used as illustrative examples. The proposed feedback controller forces the chaotic trajectory to the stable manifold as OGY method does. Simulation results are presented to show the effectiveness of the proposed design method.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.107-112
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• 1990

It is necessary to develop graphic MMI (Man-Machine Interface) for the maximum utilization of our installed ADS (Automated Distribution System) for which an operator types and executes string commands. Considering the restrictions and characteristics of the installed ADS and the data for modelled distribution lines, we calculated the time of periodic data acquisition for large number of points. And we presented the performance and characteristics of the graphic MMI system which will be developed and which will facilitate SCADA(Supervisory Control And Data Acquisition) functions.

• Communications of the Korean Mathematical Society
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• v.15 no.4
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• pp.675-681
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• 2000

Let f : M longrightarrow M be a homotopically periodic self-map of a closed surface M. Except for M = $S^2$, the Nielsen number N(f) and the Lefschetz number L(f) of the self-map f are the same. This is a generalization of Kwasik and Lee's result to 2-dimensional case. On the 2-sphere $S^2$, N(f) = 1 and L(f) = deg(f) + 1 for any self-map f : $S^2$longrightarrow$S^2$.