• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9C
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• pp.922-927
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• 2009

Utilization problem of the limited spectrum is the one of the most important issues in wireless communication systems. Cognitive radio technique which is finding and utilizing frequency holes is also one of those techniques. Specially, the spectrum sensing technique to detect the primary user signal is a core technology in cognitive radio area. In this paper, we propose the spectrum sensing algorithm using Bussgang theorem. The proposed algorithm calculates the statistical difference between the Gaussian noise and the primary user signal by applying Bussgang theorem to the received signal. The algorithm is not affected by noise uncertainty and can detect the primary user signal in the very low SNR environment. We evaluate the algorithm through computer simulations with 12 ATSC A/74 DTV signal captures based on IEEE 802.22 WRAN and formulate the sensing threshold for the proposed scheme.

• Journal of The Korean Association of Information Education
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• v.14 no.3
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• pp.449-459
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• 2010

Using a geometric computer program achieve learning effects as handling various function and has advantage to overcome the environment of classroom through providing an inquiring surroundings in the figure learning at an elementary school. There are many software for drawing the geometric. But currently most is focus on how to use the softwares without contents. So, It is necessary to develope a geometric software adapted cognitive development of primary schoolchildren. This study is aim to analyze elementary mathematic curriculum based on Van Heiles theory, to develope the software(Geometry for Kids : GeoKids) considering cognitive level of the primary schoolchildren. This software is developed to substitute a ruler and a compass considering cognitive level of the primary schoolchildren. Using mouse, GeoKids software help a child to draw easily lines and circles and this software notice another lines and circle automatically for a more accurate drawing figures. Children can use practically this software in connection with subjects of elementary mathematic curriculum.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.2
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• pp.184-191
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• 2017

This paper presents cluster based hybrid spectrum sensing system for M2M services. For each cluster, secondary nodes within the transmission radius of the primary node use hard decision method through local spectrum sensing to determine whether the primary node exists. And the other secondary nodes and the secondary nodes having poor radio channel conditions judge the existence of the primary node through the soft decision method of the values obtained by performing the cooperative spectrum sensing. In the proposed hybrid spectrum sensing system, the performance according to the number of secondary nodes is analyzed with the conventional system over Rayleigh fading channel. As the number of cooperative sensing users increased to 2, 3 and 4, the cluster error probability decreased to 0.5608, 0.5252 and 0.4001 at SNR of -10[dB] respectively. Since the proposed system uses less overhead traffic, it is found that it is more effective in terms of frequency usage than the conventional system using soft decision-soft decision and soft decision-hard decision methods.

• Journal of The Korean Association of Information Education
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• v.25 no.3
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• pp.511-525
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• 2021

The purpose of this study is to develop a design guideline to provide user-friendly experience and convenience for the online support system for the curriculum at primary/secondary schools. To achieve the objective, best practices of overseas on the online support system for curriculum as well as prior research were analyzed. In addition, UX/UI usability problems and needs were derived through a survey of 74 professionals and teachers who are monitoring NCIC and high school credit system sites. Based on the analysis of best practices of overseas and survey results, the draft of the design guideline was derived, and Delphi method was conducted by experts to re- vise the design guidelines and evaluate their validity. This study is meaningful in that it suggests the direction of improvement of the system currently being serviced and the direction of the design of the system to be developed in the future, by providing design guidelines that can be generally applied to online support systems that perform tasks related to the curriculum.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.1026-1031
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• 2022

Cognitive Radio Ad-Hoc Networks (CRAHNs) enable to overcome the shortage of frequency resources due to the increase of radio services. In order to avoid interference with the primary user in CRANH, channel sensing to check the idle channel is required, and when the primary user appears, the time delay due to handover should be minimized through fast idle channel selection. In this paper, throughput was improved by reducing the number of channel sensing and preferentially sensing a channel with a high probability of being idle, using reinforcement learning. In addition, we proposed a multi-channel MAC (Medium Access Control) protocol that can minimize the possibility of collision with the primary user by sensing the channel at the time of data transmission without performing periodic sensing. The performance was compared and analyzed through computer simulation.

• Research in Mathematical Education
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• v.17 no.1
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• pp.47-61
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• 2013

This paper aims to explore whether Learning Study improves teachers' subject content knowledge, pedagogical content knowledge, and attitude toward teaching mathematics. A Learning Study was conducted in a Hong Kong primary school for a research lesson on comparing the size of fractions to explore the new teacher roles.

• Management & Information Systems Review
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• v.17
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• pp.359-380
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• 2005

The aim of this study is to find out what kind of effect the management system of midium and small businesses like compensation, human resources management approach, employee benefit and service programs and managers' leadership has on the company's image which is a nonfinancial outcome and on its sale price which is a financial outcome.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.767-770
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• 2006

초등학교에서의 컴퓨터 교육의 방향은 컴퓨터의 원리를 바르게 이해하고 활용하며, 이를 통해 문제해결능력을 기르는 것이다. 본 논문에서는 컴퓨터의 원리 중에서 가장 중요한 알고리즘 개념에 대하여 초등학교 4학년 수학-나 여러 가지 문제 푸는 방법 찾기 단원을 기반으로 문제중심활동 방법을 이용하여 수업을 설계하고 현장에 적용하였다. 적용 결과를 통하여, 수학문제를 이용한 알고리즘 학습이 기존의 교수방법보다 효과가 있음을 보인다.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.11-14
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• 2001

본 논문은 컬러를 이용한 영상 검색 방법에 관한 것으로 영상 데이터의 효율적인 관리를 위해 먼저 전처리 단계로 웨이블릿 변환을 수행한 후 가장 낮은 저주파 부밴드 영상을 획득한다. 그리고, 변환 후 획득된 영상을 클러스터로 구분한 후, 고유치 및 고유 벡터를 이용하여 특징을 추출하여 색인 정보로 이용하였다. 클러스터링은 영상 화소의 컬러공간 상의 3차원 거리를 클러스터링의 기준으로 삼아 순차 영역 분할(Sequential Clustering) 방법을 적용하였다.

• Journal of the Korean Data and Information Science Society
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• v.17 no.4
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• pp.1077-1083
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• 2006

Association rule mining searches for interesting relationships among items in a given database. Association rules are frequently used by retail stores to assist in marketing, advertising, floor placement, and inventory control. There are three primary quality measures for association rule, support and confidence and lift. In this paper we present association rule mining based antecedent variables. We call these rules to antecedent association rules. An antecedent variable is a variable that occurs before the independent variable and the dependent variable.