• 디지털산업정보학회논문지
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• 제8권4호
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• pp.99-105
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• 2012

Recently, there are many user selection algorithms in multi user multiple-input multiple-output (MU-MIMO) systems. One of well-known user selection methods is Semi orthogonal user selection (SUS). It is an algorithm maximizing channel capacity. However, it is applicable only when user's antenna is one. We propose a generalized user selection algorithm regardless of the number of user's antennas. In the proposed scheme, Base station (Bs) selects the first user who has the highest determinant of channel and generates a user group that correlation with first user's channel is less than allowance of correlation. Then, each determinant of channels made up of first user's channel and a user's channel in the generated group is calculated and BS selects the next user who has the highest determinant of that. BS selects following users by repeating above procedure. In this paper, we get better performance because of selecting users who have the highest determinant of channel as well as allowance of correlation optimally calculated through matrix operations.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2008년도 학술대회 1부
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• pp.298-303
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• 2008

사용자의 과거 이동 경로 자료는 사용자의 현재 이동 위치를 예측하고 이외 관련된 서비스를 제공하는데 유용하게 사용될 수 있다. 본 논문에서는 사용자의 과거 이동 경로의 분석을 통하여 이동 중인 사용자의 시공간 위치예측 기술을 제안한다. 환경으로부터 발생한 사용자의 이동 경로를 수집하고 수집된 데이터에서 이동 경로 요약(Path Summarization)과 이동 경로 선택(Path Selection) 방법을 제안한다. 이동 경로 요약 방법은 환경으로부터 수집한 사용자의 이동 경로를 군집 분류하고, 이동 경로 선택 방법은 이동 중에 발생한 경로의 거리, 시간, 방향의 요소와 동적 정합법을 사용하여 유사성(Similarity)을 측정하며 유사성이 가장 높은 경로를 선택한다. 선택된 경로는 시간에 따른 공간 정보 빚 위치에 따른 시간 예측 서비스를 위하여 사용가능 하며, 실험을 통하여 유사성이 높은 이동 경로를 선택하는 모습을 확인하였다.

• 한국생활과학회지
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• 제19권1호
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• pp.103-117
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• 2010

The purpose of this study was broken down into four sections. First, this study identified both single workers' lifestyles and their motives for going to restaurants. The study classified the consumers and then confirmed the attributes of selection that the consumers considered important when eating out at family restaurants. Second, the study analyzed the consumers' lifestyles, motives for going to restaurants (user motive), and the attributes of selection for the restaurant. Third, the study analyzed how the attributes of selection toward the family restaurant affect the consumer's satisfaction and the consumer's intention of revisiting the restaurant. Fourth, the study analyzed how consumer satisfaction affects the intention to revisit the family restaurant. After the execution of the aforementioned four steps, the study was successful in meeting its purpose: to provide information to enhance the satisfaction of the consumer and to provide foundation material for consumer policy. In regards to the analytical method, this study performed a Frequency Analysis, Factor Analysis, Reliability Analysis, Cluster Analysis, ANOVA Analysis, and Multiple Regression Analysis. The analytical results from the study are as follows. Lifestyle was categorized into 4 factors and 4 clusters. User motive was grouped into 3 factors and 4 clusters. The attributes of selection for family restaurants were categorized into 4 factors. Based on the lifestyle cluster, the attributes of selection for family restaurants showed a statistically significant difference. In addition, based on the cluster of user motive, the attributes of selection for family restaurants showed a statistically significant difference. Lastly, the attributes of selection for family restaurants were found to affect both the intention of revisiting the restaurant and consumer satisfaction after the consumers used the restaurants.

• 전기학회논문지
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• 제60권9호
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• pp.1767-1769
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• 2011

In a CR (cognitive radio) network, channel selection is one of the important issues for the efficient channel utilization. When the CR user exploits the spectrum of primary network, the interference to the primary network should be minimized. In this paper, we propose a spectrum hole prediction based channel selection scheme to minimize the interference to the primary network. To predict spectrum hole, statistic properties of primary user's traffic is used. By using the predicted spectrum hole, channel is selected and it can reduce the possibility of interference to the primary user and increase the efficiency of spectrum utilization. The performance of proposed channel selection scheme is evaluated by the computer simulation.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.1795-1805
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• 2015

본 연구는 온라인 저널리즘의 추천기사가 대학생들의 뉴스기사 선택에 미치는 영향을 두 차원에서 분석하였다. 하나는 추천기사이고, 다른 하나는 이들 뉴스기사의 배치순위와 이용지수이다. 분석결과 11개의 추천기사 유형 중 7개 유형은 뉴스기사 선택에 긍정적인 영향을 미치는 것으로 나타난 반면, 4개 유형은 유의미하지 않은 것으로 나타났다. 뉴스기사 선택에 영향을 미치지 않은 것으로 나타난 추천기사 유형의 대부분은 댓글이나 SNS의 트윗과 관련된 것들이다. 또한 뉴스기사 및 검색어 배치순위는 뉴스기사 선택에 영향을 미치는 것으로 나타났으나 이용지수는 영향을 미치지 않은 것으로 나타났다. 한편, 뉴스기사 이용시간과 추천기사 유형 간 그리고 추천기사 유형 간 상관관계는 대부분 유의미한 것으로 나타났다. 분석결과를 종합하면, 뉴스기사 게재위치와 온라인 저널리즘의 추천기사와 같은 형식적 요인은 뉴스기사 헤드라인과 검색어 등의 내용과 더불어 뉴스 이용자들의 뉴스기사 선택에 긍정적인 영향을 미치는 것으로 결론지을 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.3945-3964
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• 2015

Since the decentralized structure and the blindness of a large-scale wireless network make it difficult to collect the real-time channel state or other information from random distributed relays, a fundamental question is whether it is feasible to perform the relay selection without this knowledge. In this paper, a Slotted ALOHA based Greedy Relay Selection (SAGRS) scheme is presented. The proposed scheme allows the relays satisfying the user's minimum transmission request to compete for selection by randomly accessing the channel through the slotted ALOHA protocol without the need for the information collection procedure. Moreover, a greedy selection mechanism is introduced with which a user can wait for an even better relay when a suitable one is successfully stored. The optimal access probability of a relay is determined through the utilization of the available relay region, a geographical region consisting of all the relays that satisfy the minimum transmission demand of the user. The average number of the selection slots and the failure probability of the scheme are analyzed in this paper. By simulations, the validation and the effectiveness of the SAGRS scheme are confirmed. With a balance between the selection slots and the instantaneous rate of the selected relay, the proposed scheme outperforms other random access selection schemes.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2008년도 학술대회 1부
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• pp.510-516
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• 2008

In ubiquitous environment, there are no limits to utilize networks whenever and wherever you are. That pervasive networks are combined with the information devices and then create various services such as car navigation of LBS(location based service) and DMB(Digital Multimedia Broadcasting). As these kinds of services are getting more various, the complexity is also getting higher and ultimately the convergence will make people feel frustrated. One of the solutions is Context-Awareness[1] technology. User interface with context-awareness filters unnecessary information and prevents users from being blocked due to the massive information. In this paper, we describe the seamless service system based on location-awareness, which is a type of context-awareness. We developed the system based on UPnP AV Framework. This system provides the automatic terminal device selection for the nomadic user. The system establishes new connections for the ongoing streaming playback session with the new AV devices without substantial loss of playback so that the user can enjoy the seamless service. The AV device selection based on the user's location needs no user's intervention or notification so it achieves the improvement of usability and complexity.

• 디지털산업정보학회논문지
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• 제10권1호
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• pp.99-104
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• 2014

Nowadays, various researches fulfill in many communication engineering area for B4G (Beyond Forth Generation). Next LTE-A (Long Term Evolution Advanced), MU-MIMO (Multi-User Multi Input Multi Output) method raises to upgrade throughput performance. However, the method of user selection is not decided because of many types and discussions in MU-MIMO system. Many existing methods are powerful for enhancing performance but have various restrictions in practical implementation. Fairness problem is primary restriction in this area. Existing papers emphasis algorithm to increase sum-rate but we introduce an algorithm about dealing with fairness problem for real commercialization implementation. Therefore, this paper introduces new user selection method in MU-MIMO system. This method overcomes a fairness problem in SUS (Semiorthogonal User Selection) algorithm. We can use the method to get a similar sum-rate with SUS and a high fairness performance. And this paper uses a hybrid method with SC-SUS (Superposition Coding SUS) algorithm and SUS algorithm. We find a threshold value of optimal performance by experimental method. We show this performance by computer simulation with MATLAB and analysis that results. And we compare the results with another paper's that different way to solve fairness problem.

• 한국ITS학회 논문지
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• 제8권3호
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• pp.100-111
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• 2009

Cognitive Radio(CR)는 우선 사용자에게 할당되어 있지만 실제로 사용되지 않는 주파수 대역을 감지하고 사용함으로써 스펙트럼 효율을 향상시킬수 있는 기술이다. 우선 사용자가 채널을 점유하게 되면 CR 사용자는 우선사용자에 대한 간섭을 피하기 위해 다른 채널로 이동해야 하므로 CR 사용자에 대한 서비스 품질의 보장이 어렵다. 본 논문에서는 우선 사용자와 CR 사용자가 공존하기 위해 CR 기지국의 전력 제어를 통해 우선 사용자에 대한 CR 사용자의 간섭을 최소화 시키면서 CR 사용자의 다양한 요구에 따른 다양한 통신 시스템 구성 변수들을 할당하기 위한 유전자 알고리즘 (Genetic Algorithm)을 이용한 최적의 채널을 찾는 동적 주파수 선택 (Dynamic Frequency Selection) 을 제안한다. 컴퓨터 시뮬레이션 수행을 통해 제안하는 무선 자원 공유 방법이 우선 사용자에 대한 간섭을 줄이고 스펙트럼 효율을 향상시키는 것을 보였다.

• International Journal of Contents
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• 제5권1호
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• pp.51-55
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• 2009

In this paper, we present a structure of personalized e-Learning system to study for a test formalized by uniform multiple-choice using on/off line mixed estimations as is the case of Driver :s License Test in Korea. Using the system a candidate can study toward the license through the Internet (and/or mobile instruments) within the personalized concept based on IRT(item response theory). The system accurately estimates user's ability parameter and dynamically offers optimal evaluation problems and learning contents according to the estimated ability so that the user can take possession of the license in shorter time. In order to establish the personalized e-Learning concepts, we build up 3 databases and 2 agents in this system. Content DB maintains learning contents for studying toward the license as the shape of objects separated by concept-unit. Item-bank DB manages items with their parameters such as difficulties, discriminations, and guessing factors, which are firmly related to the learning contents in Content DB through the concept of object parameters. User profile DB maintains users' status information, item responses, and ability parameters. With these DB formations, Interface agent processes user ID, password, status information, and various queries generated by learners. In addition, it hooks up user's item response with Selection & Feedback agent. On the other hand, Selection & Feedback agent offers problems and content objects according to the corresponding user's ability parameter, and re-estimates the ability parameter to activate dynamic personalized learning situation and so forth.