• Title, Summary, Keyword: function

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A CHARACTERIZATION OF CONCENTRIC HYPERSPHERES IN ℝn

  • Kim, Dong-Soo;Kim, Young Ho
    • Bulletin of the Korean Mathematical Society
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    • v.51 no.2
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    • pp.531-538
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    • 2014
  • Concentric hyperspheres in the n-dimensional Euclidean space $\mathbb{R}^n$ are the level hypersurfaces of a radial function f : $\mathbb{R}^n{\rightarrow}\mathbb{R}$. The magnitude $||{\nabla}f||$ of the gradient of such a radial function f : $\mathbb{R}^n{\rightarrow}\mathbb{R}$ is a function of the function f. We are interested in the converse problem. As a result, we show that if the magnitude of the gradient of a function f : $\mathbb{R}^n{\rightarrow}\mathbb{R}$ with isolated critical points is a function of f itself, then f is either a radial function or a function of a linear function. That is, the level hypersurfaces are either concentric hyperspheres or parallel hyperplanes. As a corollary, we see that if the magnitude of a conservative vector field with isolated singularities on $\mathbb{R}^n$ is a function of its scalar potential, then either it is a central vector field or it has constant direction.

Developing Function Models of Back-to-Back PWM Converters for Simplified Simulation

  • Van, Tan Luong;Lee, Dong-Choon
    • Journal of Power Electronics
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    • v.11 no.1
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    • pp.51-58
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    • 2011
  • In this paper, a function model of back-to-back PWM converters, based on the switching function, is developed for simplified simulation of power electronic application systems. For the function model, the PWM power switches are represented by dependent power sources. By using the proposed function model, the computer memory and the run time required for the simulation of power circuits can be significantly reduced. It is shown that the simulation results generated from the function models are almost the same as the ones obtained by using the switching power device model.

ZETA FUNCTIONS FOR ONE-DIMENSIONAL GENERALIZED SOLENOIDS

  • Yi, In-Hyeop
    • The Pure and Applied Mathematics
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    • v.18 no.2
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    • pp.141-155
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    • 2011
  • We compute zeta functions of 1-solenoids. When our 1-solenoid is nonorientable, we compute Artin-Mazur zeta function and Lefschetz zeta function of the 1-solenoid and its orientable double cover explicitly in terms of adjacency matrices and branch points. And we show that Artin-Mazur zeta function of orientable double cover is a rational function and a quotient of Artin-Mazur zeta function and Lefschetz zeta function of the 1-solenoid.

p-PRECONVEX SETS ON PRECONVEXITY SPACES

  • Min, Won-Keun
    • Honam Mathematical Journal
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    • v.30 no.3
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    • pp.425-433
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    • 2008
  • In this paper, we introduce the concept of p-preconvex sets on preconvexity spaces. We study some properties for p-preconvex sets by using the co-convexity hull and the convexity hull. Also we introduce and study the concepts of pc-convex function, $p^*c$-convex function, pI-convex function and $p^*I$-convex function.

Using the Maximin Criterion in Process Capability Function Approach to Multiple Response Surface Optimization (다중반응표면최적화를 위한 공정능력함수법에서 최소치최대화 기준의 활용에 관한 연구)

  • Jeong, In-Jun
    • Knowledge Management Research
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    • v.20 no.3
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    • pp.39-47
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    • 2019
  • Response surface methodology (RSM) is a group of statistical modeling and optimization methods to improve the quality of design systematically in the quality engineering field. Its final goal is to identify the optimal setting of input variables optimizing a response. RSM is a kind of knowledge management tool since it studies a manufacturing or service process and extracts an important knowledge about it. In a real problem of RSM, it is a quite frequent situation that considers multiple responses simultaneously. To date, many approaches are proposed for solving (i.e., optimizing) a multi-response problem: process capability function approach, desirability function approach, loss function approach, and so on. The process capability function approach first estimates the mean and standard deviation models of each response. Then, it derives an individual process capability function for each response. The overall process capability function is obtained by aggregating the individual process capability function. The optimal setting is given by maximizing the overall process capability function. The existing process capability function methods usually use the arithmetic mean or geometric mean as an aggregation operator. However, these operators do not guarantee the Pareto optimality of their solution. Moreover, they may bring out an unacceptable result in terms of individual process capability function values. In this paper, we propose a maximin-based process capability function method which uses a maximin criterion as an aggregation operator. The proposed method is illustrated through a well-known multiresponse problem.

The influence of sleep and sleep apnea on memory function (수면 무호흡과 수면이 기억기능에 미치는 영향)

  • Lee, Sung-Hoon;Lee, Na-Young;Park, Yun-Jo;Jon, Duk-In
    • Sleep Medicine and Psychophysiology
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    • v.5 no.2
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    • pp.177-184
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    • 1998
  • Objectives : Disturbance of sleep with or without sleep apnea may impair the memory function. Sleep deficiency, sleepiness, sleep apnea and emotional problem in sleep disorders can induce an impairment of memory function. Methods : In this study, the polysomnographies were administered to 58 sleep apnea patients and 38 sleep disorder patients without sleep apnea. Their clinical symptoms were quantitatively evaluated. Short term and long term memory were evaluated before and after polysom no graphy with Digit symbol test and Rey-Osterrieth complex figure test. And correlations among various sleep, repiratory and clinical variables were statistically studied in order to explore which variables may influence on memory function. Results and Conclusions : Results are as follows. Depth of sleep cis positively correlated with memory function. As sleep apnea increases and average saturation of blood oxygen decreases, memory function is more impaired. Emotional depression, high blood pressure, obesity or alcohol impaired memory function. However, daytime sleepiness was not significantly correlated with memory function. The possible mechanisms how above factors influence on the memory function were discussed.

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An Improvement of Performance for Cascade Correlation Learning Algorithm using a Cosine Modulated Gaussian Activation Function (코사인 모듈화 된 가우스 활성화 함수를 사용한 캐스케이드 코릴레이션 학습 알고리즘의 성능 향상)

  • Lee, Sang-Wha;Song, Hae-Sang
    • Journal of the Korea Society of Computer and Information
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    • v.11 no.3
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    • pp.107-115
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    • 2006
  • This paper presents a new class of activation functions for Cascade Correlation learning algorithm, which herein will be called CosGauss function. This function is a cosine modulated gaussian function. In contrast to the sigmoidal, hyperbolic tangent and gaussian functions, more ridges can be obtained by the CosGauss function. Because of the ridges, it is quickly convergent and improves a pattern recognition speed. Consequently it will be able to improve a learning capability. This function was tested with a Cascade Correlation Network on the two spirals problem and results are compared with those obtained with other activation functions.

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A Study of Middleman's Functions in Fisheries Port Market (수산물 산지 중도매인 기능 변화에 관한 연구)

  • Jang, Young-Soo
    • The Journal of Fisheries Business Administration
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    • v.38 no.3
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    • pp.89-108
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    • 2007
  • The purpose of the study are summarized as follows: First, it has researched the new functions of middleman in Fisheries Port Market. Second, the new functions which middleman have to perform in Fisheries Port Market consist of the origin function, marketing function, logistics function. The origin function consists of the discrimination of fish species and freshness, making the price by auction, financing, etc. Marketing function consists of various species assortment from not only fisheries port market but also non fisheries port market as frozen and import fish markets, finding the new selling markets as not broker but wholesaler, making the price and margin non through the action, processing, etc. Logistics function consist of fish stock, delivery Third, it has recognized the upcoming important problems by building up the new functions as middleman in Fisheries port Market. This study has used a questionnaire to verify 3 hypotheses. Research model, factor analysis, regression analysis. The result of this study are summarized as follows: The origin function influences positively on the effectiveness of middleman's performance in Fisheries port Market. Marketing function influences positively on the effectiveness of middleman's performance. However, logistics function did not directly influences on the effectiveness of middleman's performance.

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Correlations among the Continence Function, Cognitive Function and Activities of Daily Living in Elderly Male Patients with Dementia in a Geriatric Hospital

  • Kim, Hong Rae;Shin, Hee Joon;Wang, Joong San
    • Journal of International Academy of Physical Therapy Research
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    • v.7 no.1
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    • pp.972-978
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    • 2016
  • The purpose of this study was to identify correlations among the continence function, cognitive function, and activities of daily living(ADL) in elderly male patients with dementia in geriatric hospitals. The subjects were 64 patients aged 65 or above who were diagnosed with dementia among the hospitalized male patients in a geriatric hospital. For the subjects' cognitive function, a questionnaire developed for the Korean Mini Mental Status Examination(K-MMSE) was used. For the continence function and ADL, data were collected using a patient evaluation table. As a result, a lower level of cognitive function resulted in corresponding higher levels of dependence in all items of ADL except bathing(p<.05), and a lower level of cognitive function led to corresponding declines in the continence function(bowel control, bladder control)(p<.01). In addition, a higher level of dependence in ADL resulted in corresponding higher levels of difficulty in bowel and bladder control(p<.01). This study showed correlations among the cognitive function, ADL, and continence function of elderly men with dementia. The results of this study may be used as basic data for the management and treatment of hospitalized elderly male patients with dementia in geriatric hospitals.

EXTENDED WRIGHT-BESSEL FUNCTION AND ITS PROPERTIES

  • Arshad, Muhammad;Mubeen, Shahid;Nisar, Kottakkaran Sooppy;Rahman, Gauhar
    • Communications of the Korean Mathematical Society
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    • v.33 no.1
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    • pp.143-155
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    • 2018
  • In this present paper, our aim is to introduce an extended Wright-Bessel function $J^{{\lambda},{\gamma},c}_{{\alpha},q}(z)$ which is established with the help of the extended beta function. Also, we investigate certain integral transforms and generalized integration formulas for the newly defined extended Wright-Bessel function $J^{{\lambda},{\gamma},c}_{{\alpha},q}(z)$ and the obtained results are expressed in terms of Fox-Wright function. Some interesting special cases involving an extended Mittag-Leffler functions are deduced.