• Journal of Korean Institute of Industrial Engineers
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• v.34 no.4
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• pp.445-459
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• 2008

This paper addresses a call admission control(CAC) scheme giving handoff calls a priority over new calls for OFDMA wireless communication systems. The characteristics of OFDMA system and a variety of user QoS (Quality of Service) requirements are incorporated into the proposed CAC scheme which consists of several optimization modules for the system resource(subcarriers and power) allocations. The mathematical models and its solution methods for the embedded resource allocation problems are proposed. Some extensive computational experiments are conducted to illustrate the superiority of our CAC.

• Journal of the Korean Institute of Telematics and Electronics
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• v.15 no.5
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• pp.7-12
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• 1978

The successive-approximation analog-to digital conversion has been rosed to design the FSK Communication systems. The mathematical Boise is computed under the worst condition and the improved method of the FSK is suggested in the field of the real communication systems. The measured results show that the signal to noise ratio is more than 27dB, and it gives a good agreement with the mathematical analysis.

• Journal of the Korean School Mathematics Society
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• v.19 no.1
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• pp.103-122
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• 2016

The purpose of this study was to analyze the sentences related with mathematical modeling in the third and fourth grade mathematics textbooks in accordance with changing of Korean mathematics curricula. In the preliminary analysis, the researchers used the criteria that Kim(2010) had analyzed Mathematics in Context[MiC], and analyzed South Korean textbooks from the perspective of mathematical modeling. The researchers revised them for the analysis criteria among South Korean elementary mathematics textbooks and employed them as the analysis framework of the present study. From the mathematical modeling perspective, the study reached the following conclusions in accordance with the change of textbooks from the 7th curriculum to the 2009 revised curriculum. The contexts of real-world situations presented in the textbooks are increased in all areas except Probability and Statistics areas, the methods of expression of mathematical model are diversified in all areas except Patterns area, and the communication types are also diversified and frequencies increased in all areas except Patterns area. Based on this research, several suggestions were made for the development of future textbooks.

• East Asian mathematical journal
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• v.27 no.1
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• pp.23-33
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• 2011

Due to underutilization of spectrum under current inefficient and static spectrum management policy, various kinds of opportunistic spectrum access (OSA) strategies have appeared. Myopic policy is a simple and robust OSA strategy with reduced complexity that maximizes immediate throughput. In this paper, we propose mathematical models to evaluate the throughput and the MAC delay of a myopic policy under saturation tra c conditions. Using the MAC delay distribution, we evaluate the packet delay of secondary users under nonsaturation conditions. Numerical results are given to show the performance of the myopic policy in cognitive radio networks.

• East Asian mathematical journal
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• v.30 no.1
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• pp.23-29
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• 2014

To solve inefficient spectrum usage problem under current static spectrum management policy, various kinds of dynamic spectrum access strategies have appeared. Myopic policy, which maximizes immediate throughput, is a simple and robust strategy with reduced complexity. In this paper, we present a simple mathematical model to evaluate the saturation throughput and medium access delay of a myopic policy in the presence of multiple channels.

• Research in Mathematical Education
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• v.8 no.3
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• pp.215-226
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• 2004

The purpose of this paper is to introduce an activity of student who found purely linear algebraic solution of the Blackout puzzle. It shows how we can help and work with gifted students. It deals with algorithm, mathematical modeling, optimal solution and software.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.5
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• pp.967-974
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• 2012

In this paper, a vehicle detection algorithm with HD CCTV camera images using GMM(Gaussian Mixture Model) algorithm and mathematical morphological processing is proposed. At the first stage, background could be estimated using GMM from CCTV input image signal and then object could be separated from difference image of the input image and background image. At the second stage, candidated object were reformed by using mathematical morphological processing. Finally, vehicle object could be detected using vehicle size informations depend on distance and vehicle type in tunnel. Through real experiments in tunnel, it is shown that the proposed system works well.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.2
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• pp.291-304
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• 1999

In this work, a mathematical modeling of SAW coupled mode in SAW resonator filter, which is very useful in analyzing the characteristics of periodic electrode structure such as SAW reflective array and inter-digital transducers. was considered by mathematical analytic approach. The design and simulation method for resonator filter was also proposed by equivalent transduction matrix using this mathematical modeling. In order for a designer to simulate, and to design the coupled mode SAW resonator filters effectively that could be applied to mobile communication system, a design simulator for coupled mode filter was implemented by graphic user interface, and it was investigated by designing and analyzing practical SAW coupled mode resonator filter from a view point of application of this simulator.

• Journal of the Korean School Mathematics Society
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• v.15 no.2
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• pp.259-279
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• 2012

The purposes of this study were to investigate the effects of the use of link sheet in pre-service mathematics teachers' mathematics learning. The study was conducted in Calculus course during 1 semester with 25 pre-service mathematics teachers. According to the results of questionnaires and focused group interviews, the use of the link sheet helped students to develop deeper understandings of mathematical concepts and mathematical communication ability. In addition, the use of the link sheet encouraged students to realize the value of the mathematics and it also played a central role in creating active and self-directed learning atmosphere.

• The Mathematical Education
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• v.53 no.2
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• pp.239-261
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• 2014

The purpose of this study is to analyze the influences of discussion-based learning of mathematics using smart phone application on the middle school students' mathematics learning. For this purpose, we selected 6 open problems suitable for learning mathematical reasoning and five 3rd grade middle school students as participants who expected to participate in 6 lessons of discussion-based learning of mathematics using smart phone application. From the analysis of 6 lessons, we found the following results. First, attending the lessons of discussion-based learning of mathematics using smart phone application makes students more interested in mathematics and change their mathematics learning attitudes more positively. Second, the lessons of discussion-based learning of mathematics using smart phone application facilitate students' mathematical communication with the help of various communication methods using many functions of smart phone applications. Third, the lessons of discussion-based learning of mathematics using smart phone application provide teachers with teaching-learning environment where teachers can easily give their students consultation about mathematics learning or daily life.