Earticle

본 논문에서는 다중 사용자들이 존재하는 협력통신 시스템에서 다중 사용자 간 신호를 효율적으로 검출하기 위한 방법을 제안하였다. 협력통신 시스템의 신호 프레임 포맷 중 각 사용자 간 동기를 맞추기 위해 사용되는 동기채널의 NULL 공간에 확산코드를 삽입하여 전송하고, 수신단에서는 삽입된 확산코드들 사이의 상관관계를 이용하여 원하는 신호를 검출한다. 실험 결과로 AWGN, Rician, Rayleigh 채널에서 각각 Kasami/walsh sequence를 이용한 신호간 상관관계를 보여주며 본 논문의 실험결과를 이용하면 신뢰성 있는 협력통신이 가능할 것으로 기대된다.

In this paper, we propose an effective method for detecting signals among multi-user in cooperative communication system. Spread sequence is inserted to NULL space of synchronization channel to synchronize between each user among frame formats of the cooperative communication and then transmitted. In the receiver, the wanted signal is detected by using correlation among the inserted spread sequences. As simulation results, correlations among the signals using Kasami/Walsh sequence in AWGN, Rician, and Rayleigh channel are shown. Using the simulation results in this paper, we expect a reliable cooperative communication.

With the development of mobile edge computing, how to utilize the computing power of edge computing to effectively and efficiently offload data and to compute offloading is of great research value. This paper studies the computation offloading problem of multi-user and multi-server in mobile edge computing. Firstly, in order to minimize system energy consumption, the problem is modeled by considering the joint optimization of the offloading strategy and the wireless and computing resource allocation in a multi-user and multi-server scenario. Additionally, this paper explores the computation offloading scheme to optimize the overall cost. As the centralized optimization method is an NP problem, the game method is used to achieve effective computation offloading in a distributed manner. The decision problem of distributed computation offloading between the mobile equipment is modeled as a multi-user computation offloading game. There is a Nash equilibrium in this game, and it can be achieved by a limited number of iterations. Then, we propose a distributed computation offloading algorithm, which first calculates offloading weights, and then distributedly iterates by the time slot to update the computation offloading decision. Finally, the algorithm is verified by simulation experiments. Simulation results show that our proposed algorithm can achieve the balance by a limited number of iterations. At the same time, the algorithm outperforms several other advanced computation offloading algorithms in terms of the number of users and overall overheads for beneficial decision-making.

In this paper, we propose a deep learning approach for solving power allocation problems in massive MIMO networks. We use signal-to-interference-plus-noise-ratio (SINR) and signal-to-leak-plus-noise ratio (SLNR) criteria for linear precoder design to define the max?min and max-prod power allocation challenges. The power allocation process to each user equipment in the base station coverage takes a long time and is inefficient, hence numerous base stations are deployed to serve multiple user equipments. As a result, we develop a deep neural network (DNN) framework in which the user’s equipment position is utilized to train the deep model, which is then used to forecast the ideal power distribution depending on the user’s location. Compared to the traditional optimization approach, the DNN design helps to obtain the optimal solution of the power allocation problem within a short time via a quick-inference process. Simulation results show that the SINR criterion outperforms the SLNR one. Meanwhile, deep learning achieves excellent results in forecasting power allocation with an accuracy of 85% for the max?min strategy and 99% for the max-product approach.

Interference alignment (IA) has been studied extensively as an advanced technology to obtain the maximum degree of freedom (DoF) of multi-user wireless communication systems. This letter provides a brief review of recent works on IA. The most effective approach of IA is to deploy optimal linear transceivers by exploiting spatial characteristics of wireless channels. It is evaluated in measured multi-input multi-output (MIMO) interference channels. The implementation of IA depends on the characteristics of channel state information (CSI) feedback to the transmitters, such as imperfect, noisy, localized, delayed nature, and so on. In this work, we present a review of existing techniques for IA in typical multi-user MIMO systems. Moreover, we also consider some future research issues related to implementation. The study covers IA's feasibility conditions, solution algorithms in MIMO interference channel and MIMO multi-cell networks, with emphasis on the CSI feedback technology which remains as the major challenge of IA.

One solution to the problem of supplying energy to wireless networks is wireless power transfer. One such technology?electromagnetic radiation enabled wireless power transfer?will change traditional wireless networks. In this paper, we investigate a transmission strategy for multi-user wireless information and power transfer. We consider a multi-user multiple-input multiple-output (MIMO) channel that includes one base station (BS) and two user terminals (UT) consisting of one energy harvesting (EH) receiver and one information decoding (ID) receiver. Our system provides transmission strategies that can be executed and implemented in practical scenarios. The paper then analyzes the rate?energy (R?E) pair of our strategies and compares them to those of the theoretical optimal strategy. We furthermore propose a QoE-based mode selection algorithm by mapping the R?E pair to the utility functions.

In this paper, we investigate a regularized artificial fast fading (AFF) design for multi-user multi-input multi-output (MIMO) wiretap channels. To solve the effective channel gain reduction issue in conventional zero-forcing (ZF) based approaches, we propose a regularized AFF beamforming method by applying the minimum mean squared error (MMSE) problem and Lagrangian dual analysis. Finally, simulation results show that the proposed MMSE based AFF scheme improves the error performance of the legitimate user compared to the conventional ZF AFF method while achieving the same low probability of interception at the eavesdropper for multi-user MIMO secure transmission systems.

This paper describes a wearable multi-modal user interface design and its implementation for a teleoperated field robot system. Recently some teleoperated field robots are employed for hazard environment applications (e.g. rescue, explosive ordnance disposal, security). To complete these missions in outdoor environment, the robot system must have appropriate functions, accuracy and reliability. However, the more functions it has, the more difficulties occur in operation of the functions. To cope up with this problem, an effective user interface should be developed. Furthermore, the user interface is needed to be wearable for portability and prompt action. This research starts at the question: how to teleoperate the complicated slave robot easily. The main challenge is to make a simple and intuitive user interface with a wearable shape and size. This research provides multi-modalities such as visual, auditory and haptic sense. It enables an operator to control every functions of a field robot more intuitively. As a result, an EOD (explosive ordnance disposal) demonstration is conducted to verify the validity of the proposed wearable multi-modal user interface.

In context awareness and user intention tasks, dataset construction is expensive because specific domain data are required. Although pretraining with a large corpus can effectively resolve the issue of lack of data, it ignores domain knowledge. Herein, we concentrate on data domain knowledge while addressing data scarcity and accordingly propose a multi-channel long short-term memory (LSTM). Because multi-channel LSTM integrates pretrained vectors such as task and general knowledge, it effectively prevents catastrophic forgetting between vectors of task and general knowledge to represent the context as a set of features. To evaluate the proposed model with reference to the baseline model, which is a single-channel LSTM, we performed two tasks: voice phishing with context awareness and movie review sentiment classification. The results verified that multi-channel LSTM outperforms single-channel LSTM in both tasks. We further experimented on different multi-channel LSTMs depending on the domain and data size of general knowledge in the model and confirmed that the effect of multi-channel LSTM integrating the two types of knowledge from downstream task data and raw data to overcome the lack of data.

본 연구는 비대칭 XR 환경에서 가상 공간의 버추얼 사용자와 물리적 공간의 피지컬 사용자를 연결하기 위한 버추얼-피지컬 양방향 상호작용 시스템을 제안한다. 제안된 시스템은 비대칭 환경에서의 핵심 스토리텔링 요소를 기반으로 설계된 비대칭 XR 경험 <Treasure Hunter>를 구현하기 위해 개발되었으며, 두 사용자의 몰입감과 현존감을 증진하는 것을 목표로 한다. 본 연구는 기존 동일 공간 내 상호작용 연구나 산업 환경에서의 협업 관련 연구와 달리 비대칭 원격 환경에서의 서사적 요소와 기술적 요소를 통합적으로 다룬다는 점에서 차별성을 가지며, 향후 XR 콘텐츠 설계와 온오프라인 통합 경험 디자인에 기여할 것으로 기대된다.

This paper proposes a Virtual-Physical bidirectional interaction system for connecting virtual user and physical user in an asymmetric XR environment. The proposed system is developed to implement the asymmetric XR experience <Treasure Hunter>, designed based on key storytelling elements for asymmetric environment, aiming to enhance the immersion and presence of both users. Unlike previous studies focusing on interaction in co-located environments or collaboration in industrial settings, this research distinctively integrates narrative and technical elements in asymmetric remote environments. It is expected to contribute to the design of future XR content and the development of integrated online-offline user experiences.

The adoption of technology has always been of interest to academicians and practitioners of the field of Management Information System. This is so because without proper and adequate adoption, technology-no matter how beneficial or advanced it may be-will be of little value to users. Numerous researches, such as the researches of the Technology Acceptance Model (TAM) or the Unified Theory of Acceptance and Use of Technology (UTAUT), had been conducted to understand the human nature in association with the adoption or rejection of technologies that have bombarded the users. The coming of smart technologies (i.e., smart phones and devices), however, seems to have fundamentally changed the environment for adoption. The ubiquity combined with mobility of technology, especially when it comes to mobile apps, seem to make the old PC era of two-stage-pre and post-adoption models obsolete. A new model of adoption that identifies the determinants of technology acceptance and continuance is needed for the smart age. To this end, this paper undertakes an empirical study, by analyzing 229 users of Social Networking Service (SNS) mobile apps, to identify the role of user experience on the multi-stage adoption of technology, and provides results that User Experience (UX) plays the crucial role of bridging the separate stages of pre and post adoption of technologies. The paper concludes by providing practical implications of the new model as it relates to mobile apps and technologies, and recommendations for further studies to get a better understanding of technology adoption in the smart age.

무선랜의 가능한 미래 통신 표준으로 진행 중인 IEEE 802.11 LRLP는 사물 인터넷 (IoT) 네트워크 표준을 목표로, 드론을 포함한 사물 통신 단말들의 장거리 (long range) 통신과 저전력 동작 (low power)을 지원한다. 본 논문에서는 IEEE 802.11 LRLP 환경에서 다수의 단말들의 다중 사용자 상향 통신을 위한 자원 할당 기법을 제안한다. IEEE 802.11ax의 OFDMA 임의 접근 (random access)에 기반한 제안하는 기법에서는, AP (access point)가 성공적으로 전송받은 데이터의 크기를 기반으로 다음 차수의 임의 접근 유도를 위한 자원의 크기를 적응적으로 결정하여, 접속 단말이 최적의 크기의 자원을 선택하여 접속할 수 있도록 한다. 본 논문의 시뮬레이션 결과에 따르면 제안하는 기법은 종래의 임의 접근 기반 통신 기술의 시스템 처리율(throughput)을 크게 향상시키는 것으로 나타났다.

As a possible standardization of wireless local area network (WLAN), IEEE 802.11 LRLP is under discussion in order to support long range and low power (LRLP) communication for internet of things (IoT) including drones and many other IoT devices. In this paper, an efficient adaptive resource unit allocation scheme for uplink multiuser transmission in IEEE 802.11 LRLP networks is proposed. In the proposed scheme, which adopts OFDMA random access based transmission scheme of IEEE 802.11ax, in order to enhance the efficiency of the slotted OFDMA random access, access point (AP) traces the history of the sizes of successfully transmitted uplink data, and adjusts the sizes of resource units for the next uplink multiuser transmission adaptively. Our simulation results corroborate that the proposed scheme significantly improves the system throughput.

Virtual reality is becoming a powerful tool for various applications such as training, entertainment, surgery, tele-robotics etc. One potential use for virtual reality is to allow several users to interact in a single virtual environment, for example several students sitting in front of different computers connected over a network. In this paper, we present a loosely coupled architecture of haptic display in the multi-user virtual world. The method of controlling haptic devices as well as the way of configuring individual haptic display system are addressed. We will develop an experimental virtual reality system for two remote users and conclude with an experimental work for the task of a multi-player ping-pong and grasping of a common object.

본 논문에서는 TH PPM UWB-IR 시스템에서 다중 접속시 발생하는 간섭을 개선하기 위해 CCI canceller를 적용하여 동일 채널 상의 다중 사용자 간섭을 제거하였다. 결과에 의하면, CCI canceller를 적용함으로써 낮은 수신 전력에서도 고속의 데이터 전송이 가능한 수신 성능을 얻을 수 있었고 100Mbps의 고속 전송 시에도 최대 동시 접속 수 40까지 수용이 가능한 채널 용량을 얻을 수 있었다.

In this paper, We applied CCI canceller to remove multi-user interference in co-channel environment and improved performance of TH PPM UWB-IR system. As a result, We could get reception performance that data transmission of high speed is available in small reception power applying CCI canceller. Also, We could get permission available channel capacity to maximum access number 40 in high speed transmission environment more than 100Mbps.

개인용 스마트 디바이스의 빠른 발전과 역동적 보급은 개인 사용자들을 영상시청 중심의 소비자에서 영상의 촬영에서 공유로 확장된 프로슈머로 변화 시키고 있다. 이러한 변화 속에서 방송영상에 비견되는 소비가 발생되고 지속적으로 생산 및 공유되는 사용자 제작 영상(User Created Video,UCV)이 다양한 콘텐츠 서비스가 가능한 플랫폼으로 주목을 받고 있다. 특히 경험의 공유 목적으로 제작되는 UCV는 복수의 사용자들이 한정된 시간, 공간의 동일한 이벤트로부터 촬영된 것으로, 방송영상과 유사하게 동일한 이벤트를 다양한 앵글의 카메라로 촬영된다. 본 논문에서는 UCV의 다시점적 특성을 제시하고, 이러한 특징을 기반하여 동일한 이벤트에서 촬영된 UCV를 앵글 전환하며 시청할 수 있는 다시점 UCV 서비스를 제안하였다. 또한 사용자 만족도 설문을 통해 중복영역이 포함된 UCV의 시청방식으로 다시점 UCV 서비스를 기존의 선형적 시청방식보다 더 선호함을 알 수 있었다.

Fast advancement and dynamic diffusion of Smart device make big change to personal user. They have been extended from consumer only watching video to prosumer recording and sharing User Created Video(UCV). With this reason, as a platform for various kind of content service. Especially, UCVs for the purpose of sharing experience are recorded from same event on limited time and space by some people. These are also produced by various cameras that has each angle similar like broadcasting videos. In this paper, we present multi-view characteristic of UCV and propose Multi-view UCV service that is watching UCVs from same event through adjusting camera angle. Through user satisfaction survey, we knew that adjusting camera angle is preferred for watching UCV including overlapping part more than linear watching.

본 연구는 앱 기반으로 형성되는 사용자의 독특한 집단 특성인 브랜드 트라이벌리즘을 소개하고 모바일 쇼핑의 이용요인과 브랜드 트라이브 요인의 구조적 관계를 알아보고자 하였다. 나아가 이들 관계에 작용하는 쇼핑 앱 경험의 조절 효과를 탐색해 보고자 하였다. 이를 위해모바일 쇼핑의 경험이 있는 대학생 280명을 표본으로 추출하여 응답누락과 불성실 응답을제외하고 250명의 데이터를 타당한 자료로 분석하였다. 연구변인들의 구조 관계를 분석하기위해 구조방정식모형(SEM)을 적용하였고 경험의 조절효과를 파악하기 위해 모바일 쇼핑경험의 정도를 두 집단으로 구분하여 다집단분석을 수행하였다. 연구결과, 앱에 대한 애착은 재이용 의도에 정(+)의 영향을 주었고 짜증반응은 제한적으로 부(-)의 영향을 주는 것으로 나타났다. 트라이브의 차원 중 사회구조는 재이용 의도에 대한 강한 효과를 보였다. 모바일 쇼핑의 선행요인으로서 애착은 트라이브 커뮤니티의 사회구조 및 리니지 차원에 정(+)의 효과를보였고, 오락성은 트라이브의 사회구조, 리니지, 공동체 의식 모두에 정(+)의 영향을 주었다. 또한 앱에 대한 짜증반응은 트라이브의 사회구조에 부(-)의 영향을 보였고, 전환비용은 트라이브의 사회구조, 리니지, 공동체 의식과 모두 정(+)의 관련성을 나타냈다. 마지막으로 본 연구 결과에 기초한 이론적 및 실무적 함의를 논의하였다.

This study investigated the relationship between mobile shopping apps (applications) adoption and brand tribalism through moderating effect of user experiences. Brand tribes have been conceptualized as networks of heterogeneous users (in term of gender, age, income etc.) connected by a shared emotion toward a specific brand. The current study used a sample of 250 students who participated introductory courses of a large University in South Korea and the structural equation modeling with maximum likelihood method was applied to analyze the hypothesized model. Also, moderating effects of user experiences group (low vs. high) was analyzed by using AMOS multi-group methods. Results indicated that emotional attachment had a significant impact on reuse intention of mobile shopping apps, and irritation was negatively related to the reuse intention of apps. Also, attachment had significant effects on social structure and lineage of brand tribes, but not on sense of community. Entertainment and switching cost was directly related to brand tribes, including social structure, lineage, and sense of community. However, irritation had a significant impact on social structure of brand tribes, but not on lineage and sense of community. In particular, social structure of brand tribes had a strong influence on reuse intention of mobile shopping apps. The findings of this study suggest that app brand managers should consider hedonic benefits and switching barriers of apps for long-term relationships with the right mobile app customers.

연구목적: 장애인 보조기기서비스 품질과 장애인 삶의 질 간의 관계에서 일상생활 편의성과 서비스만족이 어떠한 매개적 메커니즘으로 작용하는지를 규명하였다. 연구방법: 서울시의 장애인 보조기기센터(4개소)를 통해 서비스를 이용한 626명(응답률 51.1%)을 대상으로 기술통계 분석, 요인분석, 경로분석 등을 실시하였다. 연구결과: 첫째, 장애인 보조기기서비스 서비스 이용을 통해 인지하게 된서비스 품질은 이용자의 일상생활편의성과 서비스 만족에 긍정적인 영향을 미치지만, 서비스 품질은이용자의 삶의 질에는 직접적인 영향을 미치지 못한다는 것을 확인하였다. 둘째, 서비스 품질이 이용자의 서비스 만족을 매개로 삶의 질에 영향을 미치는 간접효과(β=.385, p=.000)보다 서비스 품질이일상생활 편의성을 매개로 삶의 질에 영향을 미치는 간접효과(β=.484, p=.000)가 더 큰 것으로 실증되었다. 결론: 삶의 질 향상과 같은 장애인 보조기기 지원정책의 결과지향적(outcome-oriented) 성과 창출을 위해서는 서비스 만족뿐만 아니라 실질적 효과에 해당되는 보조기기 서비스 이용에 따른 일상생활 편의성을 증진 시키는 방향으로 서비스 품질을 향상시키기 위한 노력들이 수행될 필요가 있다.

Purposes: This study sought to examine the multi-mediation effects of service user satisfaction and convenience on the relations with service quality and quality of life(QOL) in assistive technology service. Method: This study executed descriptive statistics, confirmatory factor analysis, structural equation model by using survey data involving 320 service users of the assistive technology service for persons with disabilities in the Seoul. Results: Firstly, service quality impacted positively on the service user satisfaction and convenience for user of assistive technology service. but service quality impacted not on QOL directly. Second, the indirect effect(β=.484, p<.001) in the mediation model of service quality and convenience on the QOL was greater than indirect effect(β=.385, p<.001) in the mediation model of service quality and service user satisfaction on the QOL Conclusion: In therms of enhancing outcome-oriented performances in the policy of assistive technology in Seoul, this study suggested the policy implication for increasing service user satisfaction and convenience in everyday life.

최근 애플사의 아이폰 및 아이패드. 삼성의 갤럭시탭등 스마트폰의 대중화로 인해 멀티터치 인터페이스 기술은 일반대중뿐만 아니라 다양한 분야에서 주목을 받으며 큰 인기를 끌고 있다. 이러한 관심과 흐름 속에서 멀티 터치 인터페이스는 자연스러운 인터페이스로 부각되며 다양한 분야에서 그 활용가치가 높아지고 있다. 그러나 현재의 기술수준은 관련 콘텐츠의 부재와 개발 인프라의 부족으로 인해 대중화가 어려운 단점이 있고 특히 다자간 상호작용 콘텐츠를 제어할 수 있는 시스템은 전무한 실정이다. 이에 본 논문에서는 현재의 멀티터치 인터페이스의 문제점을 해결하고 다양한 분야에서 효과적으로 활용될 수 있는 범용 멀티 터치 인터페이스 시스템을 제안한다.

In recent years, Multi-touch interface is very popular among ordinary people because of popularizing smart-phone. For all those interests, Multi-touch interface is being magnified as a natural interface and the value of utilization is growing in various fields. However, the popularization of multi-touch interface is looked very difficult because of a lack of content and a lack of development infrastructure. especially, there is no system which can control multi-user interaction content. In this paper we propose a general-purpose multi-touch interaction system for multi-touch content producer and market invigoration of multi-touch interface.

본 연구는 다기준 의사결정(MCDM, Multi Criteria Decision Making)이 요구되는 전장 환경에서 다변하는 상황하 종합적인 상황판단을 거쳐 유연하고 신속하게 의사결정을 수행하는데 도움을 주기 위한 사용자 인터페이스 방법을 제안하는 것을 목적으로 한다. 이를 위해 기존 다기준 의사결정에 사용된 의사결정 행렬(Decision Matrix)의 제한점을 식별하고 인간 인지능력의 특징 및 한계를 고려한 언어 형태로의 정보 제공, 기준별 최소한계치 설정 등의 사용자 인터페이스 개선요소를 제안하였다. 이를 가상의 전장상황에 적용한 구체적 예시를 통해 그 개선효과를 보였다. 이렇게 고려된 사용자 인터페이스는 실시간 의사결정이 필요한 전장 환경에서 신속하고 유연한 의사결정을 지원할 수 있을 것으로 기대된다. 본 연구는 인간의 인지능력을 고려한 사용자 인터페이스 요소를 의사결정 행렬에 적용해 봄으로써 실시간 다기준 의사결정 지원에 개선가능성을 도출하였다는 것에 의의를 가진다.

This study aims to propose a user interface method to support flexible and rapid decision-making in dynamic battlefield environments where Multi-Criteria Decision Making (MCDM) is required. To this end, the study identifies limitations of the traditional decision matrix commonly used in MCDM and suggests improvements to the user interface that take into account the characteristics and limitations of human cognitive ability. These improvements include presenting information in linguistic formats and setting minimum threshold values for each criterion. The proposed approach is illustrated through a hypothetical battlefield scenario to demonstrate its effectiveness. The user interface considerations presented in this study are expected to enhance real-time decision-making by enabling more adaptable and swift responses in complex operational environments. The significance of this research lies in applying human-centered interface elements to the decision matrix, thereby offering potential improvements in real-time multi-criteria decision making support.