• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.4
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• pp.25-33
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• 2008

The performance of power constrained cooperative multi-relay system with/without opportunistic transmission is considered in Rayleigh fading. The three power allocation methods are considered to maximize the system performance when the total network power is limited. It is analyzed that the opportunistic power allocation strategy has the best performance enhancement compared to the other power allocation strategies. The opportunistic relays increases with the total network power, which induce the higher diversity order of the opportunistic cooperative diversity, consequently improves the end-to-end outage probability.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10a
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• pp.333-336
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• 2000

인터넷이 발전하면서 인터넷을 이용한 여러 서비스들이 급속히 발달하고 있다. 이런 발전에 맞추어 사용자들은 적합한 상품을 선택하는 것이 점점 어려워지고 그에 따라 운영자들은 사용자들의 요구에 맞춰 원하는 상품을 쉽게 찾게 하여 매출을 올리는 노력을 하고 있다. 이런 노력의 일환으로 기존의 사용자 데이터를 바탕으로 사용자의 선호도를 예측하고 사용자의 선호도에 따라 개인에게 적합한 상품을 추천하는 협동적 방식의 추천 시스템이 개발되어 많이 사용되는 추세이다. 본 논문에서는 현재 사용되고 있는 협동추천 시스템의 문제점을 보완할 수 있는 방법을 제시하며 실험을 통해 기존에 비해 성능이 향상되고 있음을 보인다.

• Annual Conference on Human and Language Technology
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• 2023.10a
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• pp.56-60
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• 2023

기존의 음성인식은 청장년 층에 초점이 맞추어져 있었으나, 최근 고령화가 가속되면서 노인 음성에 대한 연구 필요성이 증대되고 있다. 그러나 노인 음성 데이터셋은 청장년 음성 데이터셋에 비해서는 아직까지 충분히 확보되지 못하고 있다. 본 연구에서는 부족한 노인 음성 데이터셋 확보에 기여하고자 희소한 노인 데이터셋을 증강할 수 있는 방법론에 대해 연구하였다. 이를 위해 노인 음성 특징(feature)을 분석하였으며, '주파수'와 '발화 속도' 특징을 일반 성인 음성에 합성하여 데이터를 증강하였다. 이후 Whisper small 모델을 파인 튜닝한 뒤 노인 음성에 대한 CER(Character Error Rate)를 구하였고, 기존 노인 데이터셋에 증강한 데이터셋을 함께 사용하는 것이 가장 효과적임을 밝혀내었다.

• Journal of The Korean Association For Science Education
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• v.18 no.2
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• pp.201-208
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• 1998

Although cooperative learning strategies in many subject areas have been found to be effective, the effect of cooperative learning on academic achievement in science laboratory setting is not clear. Reported results on the effects of the strategies for higher achieving students are not also consistent. In this study, the cooperative learning strategies emphasizing student-centered learning which included higher order thinking activities were used in a elementary school science course. The cooperative and traditional learning groups were selected from fifth-grade classes, and taught about dissolution and solution for 16 class periods. The effects of the cooperative learning strategies upon students' academic achievement, science process skill, the attitude toward science instruction, and the perceptions of classroom environment were investigated. Two-way ANCOVA results revealed that the test scores of academic achievement and science process skill for the cooperative learning group were significantly higher than those of the traditional learning group. No interaction between the instruction and the level of previous achievement was found. The perceptions of confliction were higher in cooperative learning group. In the attitude toward science instruction and the perceptions of participation, however, no significant difference between the two groups was found. Educational implications are discussed.

• Proceedings of the Korea Contents Association Conference
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• 2006.05a
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• pp.215-219
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• 2006

This paper will analysis the Jam-O-Drum developed for collaborative musical experience at first. And we suggest the multi-user interactive game system Kom-O-Drum(Korean Jam-O-Drum). By combining velocity sensitive input devices like a korean drum "Jang Go" and computer graphics imagery into an LCD or PDP display, up to four simultaneous players are able to participate in a collaborative approach to game's mission. Also we introduce the input device specifications and application fields of Kom-O-Drum.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8A
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• pp.769-774
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• 2006

Based on the performance of a cooperative diversity with selection combining in Rayleigh fading, the power control range of a relay node is investigated. Also the effect of the power-limited relay node to the system performance is investigated. If the average signal-to-noise ratio(SNR) of each signal path is equal, the single relay cooperative diversity is obtained 13.5dB gain at the outage probability of $1{\times}10^{-3}$ in Rayleigh fading. We noticed that the limited power of a relay node severely degrades the system performance. Therefore the node with limited power in ad-hoc network is not recommended as a relay node in cooperative diversity system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.5
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• pp.85-91
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• 2007

In this paper, we introduce the amplify-and-forward (AF) cooperative diversity with multiple relays using phase feedback. Simulation results show that the AF cooperative diversity with multiple relays using phase feedback not only provide the better performance than the direct transmission, but also obtain the diversity gain according to the number of the cooperating terminals. The performance of proposed scheme using tolerable feedback is close to optimal performance.

• Journal of The Korean Association For Science Education
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• v.22 no.3
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• pp.508-516
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• 2002

This study investigated the influences of group composition in cooperative computer-assisted instruction (CAI) upon students' conceptual understandings, application abilities, learning motivations, and the perceptions of involvement. Seventh graders (N=97) were selected from a co-ed middle school in Seoul, and taught about 'motion of molecules' for 5 class hours. In the two treatment groups with cooperative CAI strategy, homogeneous and heterogeneous small groups were organized by the previous science achievement. Traditional instructions were administered to the comparison group. Two-way ANCOVA results revealed that the scores of the conception test for the treatment groups were significantly higher than those for the comparison group. However, there was no difference between the homogeneous and the heterogeneous groups. The scores of the three groups did not differ significantly in the application test and the learning motivation test. However, the perceptions of involvement for the treatment groups were more positive than those for the comparison group.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.478-481
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• 2010

본 논문에서는 경제학, 사회학, 수학 분야에서 수십년 전부터 연구해오던 죄수의 딜레마 게임의 협동진화에 대해 고찰해보고자 한다. 반복적 죄수의 딜레마 게임은 게임이론의 가장 기본적인 이론으로써, 사회적 상호작용, 경제활동, 국제관계 등 다양한 현상들을 모델링 하기 위한 하나의 방법이다. 그 중에 N명이 참가하는 반복적 죄수 딜레마 게임의 전략은 유전 알고리즘(Genetic Algorithms, GAs)을 통해 진화적으로 만들어 낼 수 있으며, 이 경우에 그 결과를 일반적인 내쉬 균형 이 아닌, 모든 개체들이 유전알고리즘을 통해 협동으로 수렴하도록 유도할 수 있다는 사실은 상당히 시사하는 바가 크다. 기존에 주로 연구되어오던 죄수의 딜레마 게임은 협동으로의 수렴과정에서 일반적으로 순위기반선택(Rank-based selection)과 1점 교배기법(1point crossover)을 사용한다. 그러나 순위기반선택은 모든 개체에 순위을 매겨야 하기 때문에, 개체수가 커질수록 성능이 저하되며, 1점 교배기법은 개체 값이 분산되어있을 경우, 최적해(Optimal solution)을 찾기 힘들다는 단점이 있어, 개체수가 많은 경우에 적용하기에는 비효율적이다. 본 논문에서는 토너먼트 선택기법(Tournament selection)과 자기 적응형 교배기법(Self-adaptive crossover)을 적용한 새로운 기법을 제안한다. 또한 기존 기법과 비교 실험을 통해 제안기법이 기존기법에 비해 평균 수렴시간과 수렴 횟수에서 뛰어난 성능을 보이고 있음을 확인하였다.

• Journal of The Korean Association For Science Education
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• v.23 no.1
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• pp.35-46
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• 2003

Problem solving ability, having been thought as one of the most important goals of science education is also a primary task for the current education. Indeed, the students' problem solving ability has shown almost no actual progress, despite our long accumulated science education. Under this circumstances, cooperative learning, a way to grow students' positive inter-dependence and problem solving ability in the basis of their active participation and discussion, was proposed as an effective teaching method. But, results have not consistently shown the advantage of cooperative learning over traditional learning for promoting academic achievement in science. Studies have consistently shown greater effectiveness on affective aspects. But, relatively few have focused on biology in Korea. The purpose of this study was to examine the effects of cooperative learning on the achievement and attitude of high school biology students. The pretest-posttest control group design was applied. The sample consisted of 50 11th-grade female students in experimental group(cooperative learning Student Team Achievement Division model) and 50 students in control group(traditional learning). Students in both groups recieved identical content instruction on the unit 'II. Methabolism'. These groups were treated for 13 hours during 5 weeks. Achievement data were collected using a 24-item multiple-choice test(content validity= .85). Science attitude was measured by an instrument which adapted by Kim In Hee(1994). The instrument(Cronbach $\alpha$=.89) included 40 items in four subscales: attitude toward science, social meaning of science, attitude toward science class, and scientific attitude. An analysis of covariance (ANCOVA) was used as the data analysis procedure. For the achievement data, no significant difference exists between the cooperative and traditional groups (p> .05). But, cooperative learning was effective in low-ability students(p < .05). For the science learning attitude data, cooperative learning was more effective than the traditional one(p< .05). Students in the cooperative group acheived better than those in traditional one especially in the subscale of attitude toward science class. There was no meaningful difference of the two methods in both high and average ability students, while cooperative learning was more effective than the traditional one in low ability students(p<.05).