• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.2
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• pp.152-161
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• 2009

As follow jamming signals in a FHSS system cause malfuctioning in the code tracking circuits using early-late gates, we need a code tracking circuit that is robust against the follow jamming signals. In this paper, we propose a code tracking circuit using a linear clipper-Gaussian filter algorithm to remedy the malfunctioning due to the follow jamming signals in FHSS systems. We investigate the mechanism of the malfunctioning of the code tracking circuit and verify that the proposed linear clipper-Gaussian filter metigates the problem through mathematical analysis and computer simulations.

• The Journal of Information Technology
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• v.5 no.4
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• pp.89-97
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• 2002

A web based courseware was designed and implemented for teaching number 0 to 5 to students of first grade in elementary school. The leveled learning program, according to the difference of learning abilities between learners, provides them with the contents and problems of leveled learning. This study shows the proper feedback to learners after considering their answers and provides them the effective learning situation where children learn without any restrictions of time and space. Therefore, the leveled and differentiated learning has been realized and this courseware enhanced students' interests in learning and desire for achievement. Also, it led them who can attend just for a short time to attend continuously and to participate eagerly in learning.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6C
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• pp.551-559
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• 2005

Estimation of unknown signal parameters with sensor array measurements has been investigated quite extensively. Also, there has been in recent years an explosive increase in the number of mobile users in wireless cellular systems, thus contributing to growing levels of multi-user interference. To overcome this problem, application of adaptive antenna array techniques to further increase the channel capacity has been discussed. In this paper, a new model of locally scattered signals in the vicinity of mobiles is proposed by defining the mean steering vector and is manipulated mathematically for several distributions. Under this model an estimation method of the angle of arrival(AOA) is investigated based on a weighted subspace fitting(WSF) technique. Statistical analysis and simulations are also considered.

• Journal of Digital Contents Society
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• v.10 no.2
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• pp.367-373
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• 2009

Computer programming education helps students understand abstract concepts better and solve given problems independently. Many previous studies on programming education have focused on procedural programming languages such as BASIC and C, but studies on objected-oriented program ming language like JAVA is rare. This paper examines how an architectural neural, objected-oriented JAVA programming study system can improve logical thinking ability and encourage self-led study and stimulate interests in computers among elementary school students. The system has been developed and is suitable for distributed Internet environment. The experiment results demonstrated that the objected-oriented programming education enhances logical thinking ability, exerts a positive impact on student achievement in math and science, and stimulate interests in computers.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.1
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• pp.93-101
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• 1997

Generally the traditional optimization methods have possibilities not only to give a different optimum value according to their starting point, but also to get to local optima. On the other hand, Genetic Algorithm (GA) has an ability of robust global search. In this paper, a new optimization method - the combination of traditional optimization method and genetic algorithm - is presented so as to overcome the above disadvantage of traditional methods. In order to increase the efficiency of the hybrid optimization method, a knowledge-based reasoning is adopted in the part of mathematical modeling, algorithm selection, and process control. The validation of the developed knowledge-based hybrid optimization method was examined and verified applying the method to nonlinear mathematical models.

• Journal of the Korean Geotechnical Society
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• v.31 no.4
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• pp.13-18
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• 2015

Considering dredged ground is consolidated more than one meter, Compression index prediction is very important. But, UD-sampling and consolidation test are impossible because of high moisture content and weak shear strength. This paper demonstrates the compression index relation, $C_{c(d)}=F(e_d,C_c)$, between in-situ and dredged clay using N. Keith Tovey's Omega point and soil physical properties. Good relationship is confirmed between proposed formula and measured primary consolidation result on dredged ground in The Republic of Korea.

• The KIPS Transactions:PartC
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• v.9C no.6
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• pp.927-934
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• 2002

In order to provide various multimedia services in a wireless network, the call admission control for wireless channels should be resolved at the time of call setup and handoff by moving mobile terminal. In this paper. we propose a reliable DCAC( Distributed Call Admission Control)scheme using virtual cluster concept. The proposed DCAC scheme considers the state of $1^{st}$ and $2^{nd}$ adjacent cells to provide a reliable call handling. The proposed scheme is analyzed by simulations and mathematical methods.

• Journal of IKEEE
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• v.25 no.3
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• pp.462-466
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• 2021

DVR is a device that compensates for voltage fluctuations in distribution lines and is generally used in combination with a device that compensates reactive power and improve power factor. Such a coupling compensator has the disadvantage of being relatively difficult to control and bulky. In this paper, mathematical analysis of the maximum magnitude of the compensation voltage, phase angle, compensable reactive power and active power was performed in order to simultaneously compensate the reactive power and voltage fluctuation of the distribution line by applying the power angle control method of the DVR. A control algorithm for charging active power to the battery and supplying stored energy when the voltage is changed was developed and the results were confirmed through Matlab simulation.

• Journal of The Korean Association of Information Education
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• v.23 no.4
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• pp.343-353
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• 2019

The purpose of this study is to analyze the elementary pre-service teachers' preferred strategies while they solve problems which require number sense and to study a way to improve their number sense ability based on computational thinking. In a survey with 57 elementary pre-service teachers using the instrument consisting of two different number sense components, they preferred much more the rule-based strategies to the number sense-based strategies, which was consistent with the prior studies[13][14][20]. To change this situation, we present a way to improve their number sense ability by utilizing the analyzed results and the nine computational thinking components which were suggested by CSTA and ISTE(2011).

• Korean Journal of Childcare and Education
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• v.15 no.1
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• pp.37-55
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• 2019

Objective: This study investigated whether executive function has a significant relationship to concrete, picture, and language clue tasks of the arithmetic story problem-solving ability, and its effects. Methods: The participants in the study were 112 young children at childcare centers. The following methods were used to evaluate executive function: Day-Night/Flag-Raising tasks, DCCS tasks, and digit span-reverse digit span methods. To measure the arithmetic story problem-solving ability concrete, picture, and language clue tasks were evaluated. Results: First, the higher the child's age, the higher their executive function and arithmetic story problem-solving abilities were. Second, there is a significant positive correlation between a young child's executive function and arithmetic story problem-solving ability. Third, when the task presentation method varied for concrete, picture, and language clue tasks, the effect of the subordinate factor of the execution function of the arithmetic story problem-solving ability also varied. Conclusion/Implications: Analysis confirmed the relationship between young children's executive function and arithmetic story problem-solving ability. The results are meaningful in showing that the sub-factors of the executive function have different influences on concrete, picture, and language clue tasks of the arithmetic story problem-solving ability.