• Journal of the Korean Institute of Telematics and Electronics B
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• v.28B no.7
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• pp.557-565
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• 1991

The activated sludge process is a commonly used method for terating sewage and waste waters. The process is chatacterized by a lack of measurement instrumentations and control goals that are not always clear and not well understood. In such process, fuzzy control concept may be able to be adapted, do this paper presents a design method for fuzzy controller based on a selected sub-rule set from the total rule set and a multivariable fuzzy reasoning algorithms. In order to achievesystematic and efficient control of the activated sludge process under a great deal of disiutbances and a variety of perfotmance characteristics, a top-level rule-based fuzzy controller os proposed which provises lower-controllers with the suitable set-points according tothe onput-output states of the process.

• The Journal of the Korea Contents Association
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• v.18 no.3
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• pp.557-567
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• 2018

This paper studies the relationship between general investors' allotment ratio and underpricing for the companies that were newly listed in KOSDAQ market after the 20% rule, from March 2004 to December 2013, by empirical analysis. It is shown that the excess allotment ratio over 20% has a strong explanatory power for underpricing ratio under the 1% significance level. Furthermore, the general investors' allotment ratio is a significant explanatory variable of underpricing ratio under the 5% significance level. There are many hypotheses about underpricing, however, if underpricing is evident with high allocation ratio for general investors, it can be regarded as a signal of company's confidence in earnings after listing. In conclusion, this study reveals that general investors' allotment ratio can be used as a major explanatory variable that has a significant effect on the degree of undervaluation in the IPO market.

• Steel and Composite Structures
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• v.28 no.5
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• pp.541-557
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• 2018

This paper presents the influence of carbon nanotubes (CNTs) waviness and aspect ratio on the vibrational behavior of functionally graded nanocomposite sandwich annular sector plates resting on two-parameter elastic foundations. The carbon nanotube-reinforced (CNTR) sandwich plate has smooth variation of CNT fraction along the thickness direction. The distributions of CNTs are considered functionally graded (FG) or uniform along the thickness and their mechanical properties are estimated by an extended rule of mixture. In this study, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. Effects of CNT distribution, volume fraction, aspect ratio and waviness, and also effects of Pasternak's elastic foundation coefficients, sandwich plate thickness, face sheets thickness and plate aspect ratio are investigated on the free vibration of the sandwich plates with wavy CNT-reinforced face sheets. The study is carried out based on three-dimensional theory of elasticity and in contrary to two-dimensional theories, such as classical, the first- and the higher-order shear deformation plate theories, this approach does not neglect transverse normal deformations. The sandwich annular sector plate is assumed to be simply supported in the radial edges while any arbitrary boundary conditions are applied to the other two circular edges including simply supported, clamped and free.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.3
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• pp.539-557
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• 2013

A novel multifocus image fusion algorithm based on NSCT is proposed in this paper. In order to not only attain the image focusing properties and more visual information in the fused image, but also sensitive to the human visual perception, a local multidirection variance (LEOV) fusion rule is proposed for lowpass subband coefficient. In order to introduce more visual saliency, a modified local contrast is defined. In addition, according to the feature of distribution of highpass subband coefficients, a direction vector is proposed to constrain the modified local contrast and construct the new fusion rule for highpass subband coefficients selection The NSCT is a flexible multiscale, multidirection, and shift-invariant tool for image decomposition, which can be implemented via the atrous algorithm. The proposed fusion algorithm based on NSCT not only can prevent artifacts and erroneous from introducing into the fused image, but also can eliminate 'block effect' and 'frequency aliasing' phenomenon. Experimental results show that the proposed method achieved better fusion results than wavelet-based and CT-based fusion method in contrast and clarity.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.557-560
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• 2004

추천 시스템에서부터 1:1 마케팅에 이르는 전자 상거래의 다양한 응용 영역에서, 개별 사용자로부터 개인화된 사용자 프로파일을 구축하는 것은 매우 중요하다. 이러한 프로파일들은 사용자들의 구매 행위와 같은 개인별 행동들을 설명해주며, 특히 다양한 데이터 마이닝(Data Mining) 기술들을 이용해 사용자의 거래 기록으로부터 학습된 규칙들을 발견해낼 수 있다. 발견된 규칙들 중에는 거짓이거나 연관 없거나 또는 하찮은 것들도 존재하기 때문에, 가장 중요한 문제 가운데 하나는 발견된 규칙들을 처리후-분석을 어떻게 수행하느냐이다. 예를 들어, 발견된 규칙을 사용자 프로파일에 적합한 것인지를 확인할 때 좋은 규칙과 나쁜 규칙을 어떻게 판명하는가 하는 문제이다. 이 논문에서는 규칙을 확인하는 과정에서 객관적 척도를 이용하는 방법을 제안하였다.

• Smart Structures and Systems
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• v.25 no.5
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• pp.543-557
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• 2020

This paper presents a series of experimental and numerical investigations on a vertical isolation system with quasi-zero stiffness (QZS) property. The isolation system comprises a linear helical spring and disk spring. The disk spring is designed to provide variable stiffness to the system. Orthogonal static tests with different design parameters are conducted to verify the mathematical and mechanical models of the isolation system. The deviations between theoretical and test results influenced by the design parameters are summarized. Then, the dynamic tests for the systems with different under-load degrees are performed, including the fast sweeping tests, harmonic excitation tests, and half-sine impact tests. The displacement transmissibility, vibration reduction rate, and free vibration response are calculated. Based on the test results, the variation of the transmission rule is evaluated and the damping magnitudes and types are identified. In addition, the relevant numerical time history responses are calculated considering the nonlinear behavior of the system. The results indicate that the QZS isolation system has a satisfactory isolation effect, while a higher damping level can potentially promote the isolation performance in the low-frequency range. It is also proved that the numerical calculation method accurately predicts the transmission character of the isolation system.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.557-569
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• 2023

Amphibians are the world's most threatened group of animals, with approximately 41% facing extinction. Contrary to this global trend, the number of amphibian species in Korea has increased by approximately 53.3% over the past 20 years. In particular, salamanders within the genus Hynobius showed even greater diversity, with the number increasing three-fold from two species to seven. However, morphological and ecological traits required for the clear differentiation of these animals are yet to be determined, leading to much confusion. In this study, we investigated the validity of using size traits for species identification, as this method is currently considered a rule of thumb when differentiating Geoje salamanders (Hynobius geojeensis), cryptic Uiryeong salamanders (H. perplicatus), and Korean small salamanders (H. unisacculus). Our study revealed that sex, study period, and habitat were all factors associated with significant differences in snout-vent length, head width, and body weight. Differences in these size traits were evident both between and within species. Our results show that body size traits applied in the recent classification of the three new salamander species could not be seen as a suitable criterion. Such identification methods based solely on body size not only cause great confusion in the field but will also limit future research on Korean Hynobius salamanders.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.29-38
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• 2016

A financial institution operated by cooperatives, abiding by the principle set by the cooperative federation, is comprised of a numerous financial institutions. Most of these small institutions are operated within local areas, providing financial services for coop members. The Financial Supervisory Regulations that supervises security professionals, organizations, and budgets are established entirely based on commercial banks in which the application of these regulations on coop financial institutions may not be proper. This paper aims to provide an efficient IT security policy for nation-wide financial institutions operated by the Cooperative Federation by analyzing its security personnel managements and adequacy.

• School Mathematics
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• v.10 no.4
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• pp.557-571
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• 2008

The objective of this paper is to study De Morgan's thoughts on teaching and learning negative numbers. We studied De Morgan's point of view on negative numbers, and analyzed his didactical approaches for negative numbers. De Morgan make students explore impossible subtractions, investigate the rule of the impossible subtractions, and construct the signification of the impossible subtractions in succession. In De Morgan' approach, teaching and learning negative numbers are connected with that of linear equations, the signs of impossible subtractions are used, and the concept of negative numbers is developed gradually following the historic genesis of negative numbers. Also, we analyzed the strengths and weaknesses of the De Morgan's approaches compared with the mathematics curriculum.

• The Mathematical Education
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• v.61 no.4
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• pp.539-557
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• 2022

A research field develops by experiencing several turns of paradigms. Mathematics education research have experienced those turns as well. Still, the dominant perspective is that mathematics education research should be scientific and objective. In this article, I suggest that this need not to be the prime rule to follow and that the mathematics education field will fertile by discussing extraordinary cases which may seem controversal to be recognized as valid research work. To this end, I first briefly describe the necessity of open discussions among researchers for a field to develop. Then, I introduce fiction writing, a resesarch method derived from arts-based research, as an extraordinary case for open discussions. The benefit of Arts-based research is on that it takes an holistic approach to how we know by embracing emotion and emphathy as means for knowing. Because of this trait, arts-based research holds a powerful potential for influencing a wide range of people, both inside and outside of the resesarch field. Following this, I present a fiction about a prospective teacher who participated in an activity for designing educative curriculum materials. By doing so, I sought to provoke discussions among mathematics education researchers about what to include as a valid research work, possible standards for reviewing arts-based resesarch.