• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권1호
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• pp.1-19
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• 2020

In an underlay cognitive simultaneous wireless information and power transfer (SWIPT) network, communication from secondary user (SU) to secondary destination (SD) is accomplished with decode-and-forward (DF) relays. Multiple energy-constrained relays are assumed to harvest energy from SU via power splitting (PS) protocol and complete SU secure information transmission with beamforming. Hence, physical layer security (PLS) is investigated in cognitive SWIPT network. In order to interfere with eavesdropper and improve relay's energy efficiency, a destination-assisted jamming scheme is proposed. Namely, SD transmits artificial noise (AN) to interfere with eavesdropping, while jamming signal can also provide harvested energy to relays. Beamforming vector and power splitting ratio are jointly optimized with the objective of SU secrecy capacity maximization. We solve this non-convex optimization problem via a general two-stage procedure. Firstly, we obtain the optimal beamforming vector through semi-definite relaxation (SDR) method with a fixed power splitting ratio. Secondly, the best power splitting ratio can be obtained by one-dimensional search. We provide simulation results to verify the proposed solution. Simulation results show that the scheme achieves the maximum SD secrecy rate with appropriate selection of power splitting ratio, and the proposed scheme guarantees security in cognitive SWIPT networks.

• 방송공학회논문지
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• 제12권4호
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• pp.342-349
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• 2007

In general multi-view system, all the view sequences acquired at the server are transmitted to the client. However, this kind of system requires high processing power of the server as well as the client, thus it is posing a difficulty in practical applications. To overcome this problem, a relatively simple method is to transmit only two view-sequences requested by the client in order to deliver a stereoscopic video. In this system, effective communication between the server and the client is one of important aspects. Therefore, we propose an efficient multi-view system that transmits two view-sequences according to user's request. The view selection process is integrated into MPEG-21 DIA (Digital Item Adaptation) so that our system is compatible to MPEG-21 multimedia framework. Furthermore, multi-view descriptors related to multi-view camera and systems are newly introduced. The syntax of the descriptions and their elements is represented in XML (extensible Markup Language) schema. Intermediate view reconstruction (IVR) is used to reduce such discomfort with excessive disparity. Furthermore, IVR is useful for smooth transition between two stereoscopic view sequences. Finally, through the implementation of testbed, we can show the valuables and possibilities of our system.

• 한국전자통신학회논문지
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• 제8권5호
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• pp.687-693
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• 2013

본 연구는 스마트폰 기반의 초등학교 컴퓨터 교육을 위한 디지털 교과서를 설계하고 구현한 것으로서, 디지털 교과서의 장점인 상호작용성을 극대화하여 개인의 수준과 선택에 따라 자율적으로 공부 할 수 있는 자기주도 학습능력을 배양할 수 있는 방법을 제안한다. 디지털 교과서의 콘텐츠로 본 연구에서는 엑셀의 차트 기능을 활용하였다. 구현된 디지털 교과서를 초등학교 학습자들을 대상으로 평가해본 결과 기존에 활용되던 인쇄형 자료에 비해 차트를 작성하는 과제의 수행시간이 단축되었다.

• 한국멀티미디어학회논문지
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• 제21권10호
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• pp.1162-1170
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• 2018

This paper presents an augmented reality system for multiple users. The proposed system performs ar image-based pose estimation of users and pose of each user is shared with other uses via a network server. For camera-based pose estimation, we install multiple markers in a pre-determined space and select the marker with the best appearance. The marker is detected by corner point detection and for robust pose estimation. the marker's corner points are tracked by optical flow tracking algorithm. Experimental results show that the proposed system successfully provides an augmented reality application to multiple users even when users are rapidly moving and some of markers are occluded by users.

• 한국경영과학회지
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• 제35권4호
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• pp.55-79
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• 2010

This study deals with a model for platform competition in a two-sided market. We suppose there are both direct and indirect network externalities between suppliers and users of each platform. Moreover, we suppose that both users and suppliers are distributed in their relative affinity for each platform type. That is, each user [supplier] has his/her own preferential position toward each platform, and users [suppliers] are horizontally differentiated over [0, 1]. And for analytical tractability, some parameters like direct and indirect network externalities are the same across the markets. Given the parameters and the pricing profile, users and suppliers conduct subscription game, where participants select the platform that gives them the highest payoffs. This game proceeds according to a replicator dynamics of the evolutionary game, which is simplified by properly defining gains from participant's strategy in the subscription game. We find that depending on the strength of these network effects, there might either be multiple stable equilibria, at which users and suppliers distribute across both platforms, or one unstable interior equilibrium corresponding to the market tipping in favor of either platform. In both cases, we also consider the pricing power of competing platform providers under the framework of the Stackelberg game. In particular, our study examines the possible effects of the type of competition between platform providers, which may constrain the equilibrium selection in the subscription game.

• 대한한의학회지
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• 제21권4호
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• pp.129-137
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• 2000

Objectives: The aim of this study was to investigate the attitude toward the oriental hospital among 1,234 outpatients. Methods: A questionnaire about the general characteristics of patients, the decision-maker of use and the reason of choice or alteration was implemented. Results: The results of this survey as follows: Among outpatients 56.4 % were female in sex, 25.6 % were below 9 years of age; in educational level, 50.1 % were college graduates. Among outpatients, 33.6% chose the oriental hospital as their first choice and the rest were recommended by other persons. The recommenders were mostly relatives(73.9 %), female(73.4 %), young(30-39 years old, 40.1 %), high educational level (above the college, 54.9 %) people. 37.8 % among outpatients were secondary selection after the western medical clinic for the same symptom and sign. 7.0 % were the concomitant users of both therapies. 62.8 % among the concomitant users did not notify the western doctor about the dual therapies. The reasons they did not notify their Western doctors were 'be afraid of western doctor s bias' (42.6 %), 'no special reason' (29.6 %). Conclusions: The appropriate transfer system between oriental and western clinic must be constructed and the proper recognition about dual therapies will be needed among patients and doctors who practice both kinds of medicine.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 춘계학술대회
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• pp.75-78
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• 2018

최근 디지털 음반시장의 성장으로, 들을 수 있는 음악의 양이 기하급수적으로 늘어나고 있다. 이로 인해 온라인 음원 서비스 이용자들은 마음에 드는 음악을 선택하는데 어려움을 겪고, 많은 시간을 낭비하게 되었다. 본 논문에서는 온라인 음원 서비스 이용자들이 겪는 선택의 어려움을 최소화하고, 낭비되는 시간을 줄이기 위한 추천 기법을 제안하고자 한다. 제안하는 기법은 개인정보의 이용 없이 아이템을 추천할 수 있는 아이템 기반 협업필터링 알고리즘을 사용한다. 더 정확한 추천을 위해 음원의 메타데이터를 이용하여 사용자의 선호도를 예측하고 선호도가 높은 Top-N개의 음악을 최종적으로 추천한다. 실험을 통해 제안하는 기법이 메타데이터를 이용하지 않을 때보다 추천 성능이 향상되는 것을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1534-1538
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• 2005

In this paper, we propose a method to detect contours of a face, eyes, and a mouth of a person in the color image in order to make an avatar automatically. First, we use the HSI color model to exclude the effect of various light conditions, and find skin regions in the input image by using the skin color defined on HS-plane. And then, we use deformable templates and genetic algorithm (GA) to detect contours of a face, eyes, and a mouth. Deformable templates consist of B-spline curves and control point vectors. Those represent various shapes of a face, eyes and a mouth. GA is a very useful search algorithm based on the principals of natural selection and genetics. Second, the avatar is automatically created by using GA-detected contours and Fuzzy C-Means clustering (FCM). FCM is used to reduce the number of face colors. In result, we could create avatars which look like handmade caricatures representing user's identity. Our approach differs from those generated by existing methods.

• 재활복지공학회논문지
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• 제6권1호
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• pp.29-35
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• 2012

대부분의 보완 대체 의사소통은 별도의 전용기기를 사용하여 제공하거나 휴대가 어려운 데스크톱 또는 현재는 거의 사용하지 않는 Windows 기반의 태블릿 등에서 제공되는 연구들이 대부분이었다. 게다가, 앞선 연구들의 고유명사 처리는 사전을 만들어 제공하는 형식이었기 때문에 무수히 많은 고유명사에 대한 처리가 거의 불가능하였고 향후 연구과제로 많이 지적되고 있었다. 본 논문에서는 현재 급속도록 보급되고 있는 스마트 기기를 활용하여 과거의 연구 과제로 남았던 고유명사 처리에 대한 해결 방법을 제안한다. 또한, 신체장애를 가진 사람을 위하여 버튼을 이용한 입력방법과 키보드를 통한 입력 시 생길 수 있는 오류에 대한 보완 방법도 제안한다. 본 연구에서는 제안하는 보완 대체 의사소통 시스템의 유용성을 확인하기 위하여 안드로이드 기반의 모바일 어플리케이션을 구현하였다. 실험결과 사용자의 위치와 선택에 따라 주변에 있는 다양한 고유명사가 도출되어 문장을 생성하는데 도움을 주는 것을 확인할 수 있었다.

• 한국통신학회논문지
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• 제31권5B호
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• pp.397-404
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• 2006

최근 광네트워크 기반 IP 서비스가 증가함에 따라 GMPLS 관리 프레임워크는 더욱 중요해지고 있다. 본 논문에서는 이러한 GMPLS 네트워크의 장애 요인들 중 다중 경로 장애 시 사용자의 트래픽 엔지니어링 복구 요구조건을 만족하고 최적의 서비스에 대한 대체 경로를 찾을 수 있는 동적 GMPLS 경로 관리 알고리즘을 제안한다. 구체적으로 GMPLS 네트워크에서 복구 조건을 만족하는 대체 경로의 가용성 조건들을 도출하고 있다. 또한 고속 대체 경로 설정 알고리즘을 제안하여 사용자의 복구 요구조건을 만족하고 서비스의 중지를 최소한으로 막을 수 있게 한다.