• Journal of the Korean Mathematical Society
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• v.36 no.4
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• pp.787-811
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• 1999

Let M be the maximal ideal space of the Banach algebra $H^{\infty}$ of bounded analytic functions on the open unit disc $\triangle$. For a positive singular measure ${\mu}\;on\;{\partial\triangle},\;let\;{L_{+}}^1(\mu)$ be the set of measures v with $0\;{\leq}\;{\nu}\;{\ll}\;{\mu}\;and\;{{\psi}_{\nu}}$ the associated singular inner functions. Let $R(\mu)\;and\;R_0(\mu)$ be the union sets of $\{$\mid$\psiv$\mid$\;<\;1\}\;and\;\{$\mid${\psi}_{\nu}$\mid$\;<\;0\}\;in\;M\;{\setminus}\;{\triangle},\;{\nu}\;\in\;{L_{+}}^1(\mu)$, respectively. It is proved that if $S(\mu)\;=\;{\partial\triangle}$, where $S(\mu)$ is the closed support set of $\mu$, then $R(\mu)\;=\;R0(\mu)\;=\;M{\setminus}({\triangle}\;{\cup}\;M(L^{\infty}(\partial\triangle)))$ is generated by $H^{\infty}\;and\;\overline{\psi_{\nu}},\;{\nu}\;{\in}\;{L_1}^{+}(\mu)$. It is proved that %d{\theta}(S(\mu))\;=\;0$ if and only if there exists as Blaschke product b with zeros $\{Zn\}_n$ such that $R(\mu)\;{\subset}\;{$\mid$b$\mid$\;<\;1}\;and\;S(\mu)$ coincides with the set of cluster points of $\{Zn\}_n$. While, we proved that $\mu$ is a sum of finitely many point measure such that $R(\mu)\;{\subset}\;\{$\mid${\psi}_{\lambda}$\mid$\;<\;1}\;and\;S(\lambda)\;=\;S(\mu)$. Also it is studied conditions on \mu for which $R(\mu)\;=\;R0(\mu)$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.6
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• pp.360-369
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• 2014

Underwater Acoustic Sensor Networks(UASN) enables varied study from collected data of underwater environments such as pollution monitoring, disaster prevention. The collected data is transmitted from underwater to terrestrial communication entity by acoustic communication. Because of the constraints of underwater environments include low data rate and propagation delay, it is difficult to apply cryptographic techniques of terrestrial wireless communication to UASN. For this reason, if the cryptographic techniques are excluded, then collected data will be exposed to security threats, such as extortion and forgery, during transmission of data. So, the cryptographic techniques, such as the authentication and key establishment protocol which can confirm reliability of communication entities and help them share secret key for encryption of data, must need for protecting transmitted data against security threats. Thus, in this paper, we propose the light weight authentication and key establishment protocol.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.1
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• pp.79-90
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• 2018

Fish ages are critical information in fish stock assessments because they are required for age-structure models such as virtual population analysis and stochastic catch-at-age models, whose outputs include recruitment strengths, a spawning stock size (abundance or biomass), and the projection of a fish population size in future. However, most countries other than the developed countries have not identified ages of fish caught by fisheries or surveys in a consistent manner for a long time (e.g.,>20 years). Instead, data about fish body sizes (e.g., lengths) have been well available because of ease of measurement. To infer age compositions of fish in a target group using fish length data, we intended to improve the length frequency analysis (LFA), which Schnute and Fournier had introduced in 1980. Our study was different in two ways from the Schnute and Fournier's method. First we calculated not only point estimates of age compositions but also the uncertainty in those estimates. Second, we modified LFA based on the von Bertalanffy growth model (vB-based model) to allow both individual-to-individual and cohort-to-cohort variability in estimates of parameters in the vB-based model. For illustration, we used data about lengths of Korean mackerel Scomber japonicas caught by purse-seine fisheries from 2000-2016.

• The Mathematical Education
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• v.56 no.4
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• pp.387-405
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• 2017

The purpose of this study is to investigate the change of students 'perception and expression about the motion of object following distance function $={x \atop 3}$ and distance function $y=\frac{x^3}{3}+3$ according to the necessity of research on students' perception and expression about integral constant. In this paper, we present the recognition and the expression of the difference of the constant in the relationship between the distance function and the speed function of the students, while examining the process of constructing the speed function and the inverse process of the distance function. This provides implications for the relationship between the derivative and the indefinite integral corresponding to the inverse process. In particular, in a teaching experiment, a constructive activity was performed to analyze the motion of two distance functions, where the student had a difference of the constant term. At this time, the students used the expression 'starting point' for the constants in the distance function, and the motion was interpreted by using the meaning. This can be seen as a unique 'students' mathematics' in the process of analyzing the motion of objects. These scenes, in introducing the notion of the relation between differential and indefinite integral, it is beyond the comprehension of the integral constant as a computational procedure, so that the learner can understand the meaning of the integral constant in relation to the motion of the object. It is expected that it will be a meaningful basic research on the relationship between differential and integral.

• Journal of Gifted/Talented Education
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• v.18 no.1
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• pp.53-77
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• 2008

This study was conducted with the focus on the process of constructing 3 definition and produced definitions as well as gifted students' conceptions of a mathematical definition In the study, the students made five types of regular polyhedrons (section1), observed them and stated their characteristics (section2) and then constructed a definition of regular polyhedrons based on their observations (section3). We divided students into two groups by analyzing students' definitions. One group made definitions that were consist with a mathematical definition of regular polyhedrons, the other one made definitions that were not. We checked if they fulfilled requirements for a mathematical definition. Researchers sought to gain various suggestions through the analysis of the observations and definition laid down by the students and through the characteristics shown by the students in the process of defining the concept.

• Smart Structures and Systems
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• v.26 no.4
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• pp.403-418
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• 2020

In recent years, the use of Fiber Reinforced Polymers (FRPs) as one of the most common ways to increase the strength of concrete samples, has been introduced. Evaluation of the final strength of these specimens is performed with different experimental methods. In this research, due to the variety of models, the low accuracy and impact of different parameters, the use of new intelligence methods is considered. Therefore, using artificial intelligent-based models, a new solution for evaluating the bond strength of FRP is presented in this paper. 150 experimental samples were collected from previous studies, and then two new hybrid models of Imperialist Competitive Algorithm (ICA)-Artificial Neural Network (ANN) and Artificial Bee Colony (ABC)-ANN were developed. These models were evaluated using different performance indices and then, a comparison was made between the developed models. The results showed that the ICA-ANN model's ability to predict the bond strength of FRP is higher than the ABC-ANN model. Finally, to demonstrate the capabilities of this new model, a comparison was made between the five experimental models and the results were presented for all data. This comparison showed that the new model could offer better performance. It is concluded that the proposed hybrid models can be utilized in the field of this study as a suitable substitute for empirical models.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.258-264
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• 2010

Most of fluid systems, such as P&ID in ships, power plants, and chemical plants, consist of various components. The components such as bends, tees, sudden-expansions, sudden-contractions, and orifices contribute to overall pressure loss of the system. The local pressure losses across such components are determined using a pressure loss coefficient, k-factor, in lumped parameter models. In many engineering problems Idelchik's k-factor models have been used to estimate them. The present work compares the k-factor based on CFD calculation against Idelchik's model in order to confirm whether a commercial CFD package can be used for pressure loss coefficient estimation of complex geometries. The results show that RSM is the best appropriate for evaluating pressure loss coefficient. Commercial CFD package can be used as a tool evaluating k-factor even though the accuracy is influenced by a turbulence model.

• Journal of Korean Home Economics Education Association
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• v.1 no.1
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• pp.33-42
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• 1989

By the comparative analysis of high school Home Economics curricula in the U.S., Japan and Taiwan, this study first attempts to understand the current Home Economics education and to access its treads for each country. Based on the findings of the analysis, the study also seeks to get the major implications of the analysis for the betterment of the Korea Home Economics Education. The main sources of information and data analyzed here are： 1) curricula for both Oklahoma and Ohio state as representatives of the U.S.； 2) Home Economics Teaching Guidelines in Japan； and 3) Home Economics curriculum in Taiwan. Content Analysis technique is applied in this study. The major elements of contents include：1) structure of the curriculum； 2) subject name； 3) unit (time) allotment； 4) goals； 5) subject areas and content composition； and 6) other related characteristics for the implementation of the curriculum. Summarized results of the study outline as follows： 1) Home Economics is offered as independently required subject with equal status to Mathematics, Science, and Social Studies subject in all three countries； 2) Sex discrimination is prohibited both in the U.S. and Taiwan, while in Japan sex equity is not secured for Home Economics educations； 3) Time allotment for Home Economics in Japan and Taiwan is similiar to that in Korea；4) Subject areas cover such fields as Foods and Nutrition, Clothing and Textiles, Home Management, and Human Development in all three countries, which is similiar to those of Korea. In addition, Consumer Education and Career Education are also covered in the U.S., whereas in Japan Child Care is offered； and 5) Curriculum can be utilized as instructional planning material due to the clear specification of instructional methods, materials, and evaluation methods on the curriculum, especially in the U.S. and Taiwan.

• Science of Emotion and Sensibility
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• v.8 no.4
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• pp.355-363
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• 2005

The adjectives for represnting emotions is important to evaluate and select the colors or color patterns. In this paper, we perform the MDS analysis, factor analysis, and cluster analysis to the Soen's experimental data obtained from the evaluation of random color patterns with 13 adjective pairs. As a result, those adjectives can be reduced 3 different factors representing emotions of weight, activity and temperature, which is approximately corresponds the results of previous researches on single colors. Also, we show that the adjectives for preference can be approximate4 by other primary adjectives for color patterns using regression analysis. This implies that one can construct a uniform emotion space for evaluating and selecting color patterns regardless of objects such as wall papers, carpets, and so on.

• Journal of Gifted/Talented Education
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• v.20 no.1
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• pp.31-59
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• 2010

Previous studies reported that gifted students' capacity on mathematics had high correlations with results of the performance assessment. However, there have been few studies that develop recommending tools through the assessment that can be used to identify mathematically gifted students or analyse their applications. Then it is difficult to use them to identify mathematically gifted students practically. Therefore, this study developed the tasks and evaluation tables for the tools. And one of them was applied for four students in Grade 1 of a middle school to simulate the assessment and characteristics assessment teachers showed were analysed. As the results, the extensive and specific information on the giftedness of the students was obtained through using the tool. The gifted capacity grasped from the order, speed, and attitudes of problem-solving was identified as observing the process of solving the task.