• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1646-1647
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• 2007

In the conventional sliding mode control(SMC), the states of controlled systems are linearly dependent because of the characteristic of the sliding surface. This means that conventional SMC can not add its robustness to other control methods. To overcome this problem, a special sliding surface with additional dynamic states has been proposed. However the additional dynamic states make it difficult to design a controller because the order ofa controller becomes higher. So, in this paper, a novel sliding surface design method, which does not require any additional dynamic state, is proposed. The relationships between the states with desirable responses can be expressed by using SVM and included in a sliding mode dynamics. The robust optimal controller with the optimal performanceand the robustness of SMC is considered.

• Journal of applied mathematics & informatics
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• v.39 no.3_4
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• pp.469-485
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• 2021

In this paper, some new classes of the higher order strongly exponentially preinvex functions are introduced. New relationships among various concepts of higher order strongly exponentially preinvex functions are established. It is shown that the optimality conditions of differentiable higher order strongly exponentially preinvex functions can be characterized by exponentially variational-like inequalities. Parallelogram laws for Banach spaces are obtained as an application. As special cases, one can obtain various new and known results from our results. Results obtained in this paper can be viewed as refinement and improvement of previously known results.

• Nonlinear Functional Analysis and Applications
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• v.27 no.1
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• pp.23-44
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• 2022

In this paper, we consider and introduce some new concepts of the biconvex functions involving an arbitrary bifunction and function. Some new relationships among various concepts of biconvex functions have been established. We have shown that the optimality conditions for the general biconvex functions can be characterized by a class of bivariational-like inequalities. Auxiliary principle technique is used to propose proximal point methods for solving general bivariational-like inequalities. We also discussed the conversance criteria for the suggested methods under pseudo-monotonicity. Our method of proof is very simple compared with methods. Several special cases are discussed as applications of our main concepts and results. It is a challenging problem to explore the applications of the general bivariational-like inequalities in pure and applied sciences.

• Honam Mathematical Journal
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• v.44 no.3
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• pp.419-431
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• 2022

Mannheim introduced the concept of a pair of curves, called as Mannheim partner curves, in 1878. Until now, Mannheim partner curves have been studied widely in the literature. In this study, we take into account of this concept according to Positional Adapted Frame (PAF) for the particles moving in the 3-dimensional Euclidean space. We introduce a new type special trajectory pairs which are called Mannheim partner P-trajectories in the Euclidean 3-space. The relationships between the PAF elements of this pair are investigated. Also, the relations between the Serret-Frenet basis vectors of Mannheim partner P-trajectories are given. Afterwards, we obtain the necessary conditions for one of these trajectories to be an osculating curve and for other to be a rectifying curve. Moreover, we provide an example including an illustrative figure.

• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.86-93
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• 2023

In this study, we investigated the various adsorption factors influencing the adsorption of heavy metal ions based on the study of the composition and physicochemical properties of scoria dispersed throughout Jeju Island. Analysis of the distribution characteristics of scoria samples collected from five areas of Jeju showed that reddish-brown-colored scoria were predominant. Analysis of scoria collected from Jeju Island showed that its mineral components are ordered as follows: SiO₂ > Al₂O₃ > Fe₂O₃ > CaO and MgO. The experimental data did not show a linear relationship in the pseudo-first-order adsorption kinetics. In contrast, a pseudo-second-order model yielded a positive linear relationship, and this model was subsequently used. It could be concluded based on an intraparticle diffusion model indicating linear relationships that the capture of metal ions on scoria is dominated by the primary adsorption step.

• Journal of applied mathematics & informatics
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• v.41 no.3
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• pp.657-685
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• 2023

This paper aims to apply the concept of Pythagorean fuzzy soft sets (PFSSs) to UP-algebras. Then we introduce five types of PFSSs over UP-algebras, study their generalization, and provide illustrative examples. In addition, we study the results of four operations of two PFSSs over UP-algebras, namely, the union, the restricted union, the intersection, and the extended intersection. Finally, we will also discuss t-level subsets of PFSSs over UP-algebras to study the relationships between PFSSs and special subsets of UP-algebras.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.167-168
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• 2020

본 연구는 학업중단청소년 패널조사 5차년도 조사(2017년) 데이터를 활용하여 학업중단 청소년의 진로불안이 우울에 영향을 미치는 과정에서 외적 보호요인으로 작용하는 사회적 관계(부모애착, 또래애착)와 내적 보호요인으로 작용하는 자아탄력성의 매개효과를 검증하고자 한다.

• International Journal of Advanced Culture Technology
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• v.12 no.2
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• pp.119-135
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• 2024

The research is centered on veteran educators in the field of early childhood education who possess more than 20 years of teaching experience and have been recognized with awards for their outstanding achievements. The selection of participants was based on specific criteria, such as the number of years of experience and recognition received from the Ministry of Education's Teaching Innovation Competition in Korea. Eight teachers who met the specified criteria were selected to participate in the study. A qualitative phenomenological research study was carried out using semi-structured interviews to gain insight into the experiences and perspectives of the participants. The study identified five main themes: cultivating interpersonal relationships, establishing interactive classroom settings, providing impactful educational methodologies, facilitating healthy habits and character education, and creating a supportive environment for teachers' well-being. The study seeks to improve comprehension of teaching methodologies and offer suggestions for professional development, teacher training, and educational policies.

• Journal of applied mathematics & informatics
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• v.42 no.3
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• pp.471-481
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• 2024

In this paper, the concept of D-sets will be applied to create D-lindelöf spaces, a new type of topological space covering the property. This is performed by using a D-cover, which is a special type of cover. The primary purpose of this work is to introduce the principles and concepts of D-lindelöf spaces. We look into their properties as well as their relationships with other topological spaces. The basic relationship between D-lindelöf spaces and lindelöf spaces, as well as many other topological spaces, will be given and described, including D-compact, D-countably compact, and D-countably lindelöf spaces. Many novel theories, facts, and illustrative and counter-examples will be investigated. We will use several informative instances to explore certain of the features of the Cartesian product procedure across D-lindelöf spaces as well as additional spaces under more conditions.

• Asia pacific journal of information systems
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• v.17 no.4
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• pp.207-228
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• 2007

Measuring Information Technology(IT) organizations' activities have been limited to mainly measure financial indicators for a long time. However, according to the multifarious functions of Information System, a number of researches have been done for the new trends on measurement methodologies that come with financial measurement as well as new measurement methods. Especially, the researches on IT Balanced Scorecard(BSC), concept from BSC measuring IT activities have been done as well in recent years. BSC provides more advantages than only integration of non-financial measures in a performance measurement system. The core of BSC rests on the cause-and-effect relationships between measures to allow prediction of value chain performance measures to allow prediction of value chain performance measures, communication, and realization of the corporate strategy and incentive controlled actions. More recently, BSC proponents have focused on the need to tie measures together into a causal chain of performance, and to test the validity of these hypothesized effects to guide the development of strategy. Kaplan and Norton[2001] argue that one of the primary benefits of the balanced scorecard is its use in gauging the success of strategy. Norreklit[2000] insist that the cause-and-effect chain is central to the balanced scorecard. The cause-and-effect chain is also central to the IT BSC. However, prior researches on relationship between information system and enterprise strategies as well as connection between various IT performance measurement indicators are not so much studied. Ittner et al.[2003] report that 77% of all surveyed companies with an implemented BSC place no or only little interest on soundly modeled cause-and-effect relationships despite of the importance of cause-and-effect chains as an integral part of BSC. This shortcoming can be explained with one theoretical and one practical reason[Blumenberg and Hinz, 2006]. From a theoretical point of view, causalities within the BSC method and their application are only vaguely described by Kaplan and Norton. From a practical consideration, modeling corporate causalities is a complex task due to tedious data acquisition and following reliability maintenance. However, cause-and effect relationships are an essential part of BSCs because they differentiate performance measurement systems like BSCs from simple key performance indicator(KPI) lists. KPI lists present an ad-hoc collection of measures to managers but do not allow for a comprehensive view on corporate performance. Instead, performance measurement system like BSCs tries to model the relationships of the underlying value chain in cause-and-effect relationships. Therefore, to overcome the deficiencies of causal modeling in IT BSC, sound and robust causal modeling approaches are required in theory as well as in practice for offering a solution. The propose of this study is to suggest critical success factors(CSFs) and KPIs for measuring performance for IT organizations and empirically validate the casual relationships between those CSFs. For this purpose, we define four perspectives of BSC for IT organizations according to Van Grembergen's study[2000] as follows. The Future Orientation perspective represents the human and technology resources needed by IT to deliver its services. The Operational Excellence perspective represents the IT processes employed to develop and deliver the applications. The User Orientation perspective represents the user evaluation of IT. The Business Contribution perspective captures the business value of the IT investments. Each of these perspectives has to be translated into corresponding metrics and measures that assess the current situations. This study suggests 12 CSFs for IT BSC based on the previous IT BSC's studies and COBIT 4.1. These CSFs consist of 51 KPIs. We defines the cause-and-effect relationships among BSC CSFs for IT Organizations as follows. The Future Orientation perspective will have positive effects on the Operational Excellence perspective. Then the Operational Excellence perspective will have positive effects on the User Orientation perspective. Finally, the User Orientation perspective will have positive effects on the Business Contribution perspective. This research tests the validity of these hypothesized casual effects and the sub-hypothesized causal relationships. For the purpose, we used the Partial Least Squares approach to Structural Equation Modeling(or PLS Path Modeling) for analyzing multiple IT BSC CSFs. The PLS path modeling has special abilities that make it more appropriate than other techniques, such as multiple regression and LISREL, when analyzing small sample sizes. Recently the use of PLS path modeling has been gaining interests and use among IS researchers in recent years because of its ability to model latent constructs under conditions of nonormality and with small to medium sample sizes(Chin et al., 2003). The empirical results of our study using PLS path modeling show that the casual effects in IT BSC significantly exist partially in our hypotheses.