• Rapid Communication in Photoscience
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• v.1 no.2
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• pp.42-42
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• 2012

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.2
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• pp.68-71
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• 2006

A class-E power amplifier is designed using 0.25$\mu$m standard CNMOS technology at 900MHz and the reliability characteristics are studied with the load network. The reliability characteristics is improved when a finite DC-feed inductor is used instead of RF choke. At the one you halt, the PAE(Power Added Efficiency) decreases from 58.0$\%$ to 35.7$\%$ and output power decreases from 120mW to 74mW in power amplifier using RF choke. However, when a finite DC-feed inductor is used with load the PAE decreases from 58.5$\%$ to 54.8$\%$ and output power decreases from 121mW to 112mW. From the simulated results, the class-E power amplifier with a finite DC-feed inductor shows superior reliability characteristics compared to rower amplifier using RF choke inductor.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.250-255
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• 2018

This paper presents a method for minimizing standby power consumption in wireless power transfer (WPT) system via magnetic resonance coupling (MRC) that operates at 6.78 MHz. The proposed circuit controls the required capacitance according to operational condition in order to reduce standby power consumption. Based on an impedance characteristic of the class-E power amplifier, operational principles of the proposed circuit are analyzed. Moreover, to verify the effectiveness of the proposed class-E power amplifier, an 8 W prototype for WPT system is implemented. The measured input power of the proposed class-E power amplifier at standby condition is reduced from 5.81 W to 3.53 W.

• Journal of applied mathematics & informatics
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• v.23 no.1_2
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• pp.505-516
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• 2007

In this paper, we provide some fundamental properties and basic theoretical results of K-class-based dedicated storage policy in a unit load system assuming the constant-space assumption that the number of storage locations for a class is not the maximum aggregate inventory position for a class but the sum of space requirement for products assigned to the class. The main theorem is that there exists a (K+1) -class-based storage layout whose expexted single command (SC) travel time is not greater than that of a K-class-based storage layout, i.e, $E(SC^*_{K+1}){\leq}E(SC^*_K)\;for\;K=1,{\cdots}$, (n-1).

• Journal of electromagnetic engineering and science
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• v.17 no.4
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• pp.221-227
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• 2017

A new approach to designing a broadband and highly efficient class-E power amplifier based on nonlinear shunt capacitance analysis is proposed. The nonlinear shunt capacitance method accurately extracts optimum class-E power amplifier parameters, including an external shunt capacitance and an output impedance, at different frequencies. The dependence of the former parameter on the frequency is considered to select an optimal value of external shunt capacitor. Then, upon determining the latter parameter, an output matching network is optimized to obtain the highest efficiency across the bandwidth of interest. An analytical approach is presented to design the broadband class-E power amplifier of a MOSFET transistor. The proposed method is experimentally verified by a 140-170 MHz class-E power amplifier design with maximum added power efficiency of 82% and output power of 34 dBm.

• Journal of the Korean Mathematical Society
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• v.58 no.1
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• pp.149-171
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• 2021

Let Cl(A) denote the class group of an arbitrary integral domain A introduced by Bouvier in 1982. Then Cl(A) is the ideal class (resp., divisor class) group of A if A is a Dedekind or a Prüfer (resp., Krull) domain. Let G be an abelian group. In this paper, we show that there is a ring of Krull type D such that Cl(D) = G but D is not a Krull domain. We then use this ring to construct a Prüfer ring of Krull type E such that Cl(E) = G but E is not a Dedekind domain. This is a generalization of Claborn's result that every abelian group is the ideal class group of a Dedekind domain.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.208-220
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• 2015

This study analyze Online class's current condition in Smart era. And suggest better operation model based on Internet Architecture. This study focuses the condition of e-learning operation model in University online class. Especially, 'Time Check Idea' that using for attendance on e-learning class has some side effects. So this study would applied 'Qualitative Check Idea Concept' on e-learning class. Question Based System, QBS is example model. QBS is leading a Learner's participation in e-class by Making Quiz. These quizs are shared with other students and refer to studing contents. Practically operating Qualitative Concept model QBS on university e-class, we can seek for the effectiveness of Qualitative e-learning model QBS.

• East Asian mathematical journal
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• v.34 no.1
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• pp.29-37
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• 2018

We introduce formal symbols of product type, of zero class, and of minimum type and show that the formal power series representations for $e^p$ and $e^q$ are formal symbols of product type giving the same pseudodifferential operator, where p and q are formal symbols of minimum type and p - q is of zero class.

• School Mathematics
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• v.17 no.2
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• pp.203-222
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• 2015

This study analyzed the classroom discourse between teacher and students based on the Mehan(1979a)'s theory to examine the characteristics of the classroom discourse between teacher and students in high school statistics class. The results of this study on the structure of class showed that the statistics class in this study adopted knowledge transmission-oriented teacher-led class in which the framework of introductiondevelopment- arrangement, which is Mehan's basic 3 stages, is clearly represented. The results of examining I-R-E sequence showed that $I_T-R_T$ structure, in which the teacher asks questions and the teacher talks about the answer, frequently appeared. And the statistics class in this study was monological class in which students hardly participated. Through these results of this study, it was found that teacher should form the statistical context, in which students can participate in discourse, and build discourse learning community and induce argumentational discourse through metaprocess elicitation.

• Journal of Advanced Navigation Technology
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• v.14 no.3
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• pp.351-357
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• 2010

This paper proposes the adaptive class-E power amplifier with maintaining high power added efficiency (PAE) to apply RFID and wireless communication system. This switch mode amplifier is used a microprocessor to control a resonator circuits and to maintain high efficiency in case of input frequency variation. To validate the adaptive amplifier operation, which is a 450MHz operating frequency and a 100MHz bandwidth, the class E amplifier is implemented. As a result, the adaptive amplifier is maintained above 60% efficiency in frequency range and has a 74.8% maximum efficiency.