• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1624-1641
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• 2015

Instantaneous relay (relay-without-delay) using interference alignment is a promising approach to neutralizing interference and improving system capacity. In Wang Chenwei's work, a 2-user scenario required both source and relay to access the global channel state information (CSI). This paper shows a new method of interference alignment improves the degrees of freedom (DoF) prominently for the 3-user MIMO interference channel with instantaneous relay. This new method is focused on the relay node that completes the alignment interference neutralization so the global CSI is obtained only once and the pressure on the base station can be mitigated. In addition, the 3-user MIMO interference channels with instantaneous relay can achieve 2M DoF when source and destination have M antennas, respectively. This method shows 33% improvement over the conventional method using interference alignment which obtains 3M/2 DoF.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.484-488
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• 2008

In ubiquitous environments, there are a large number of various mobile devices everywhere. Recently, many studies have been research on distributed resources sharing in this ubiquitous environments. However, the problems with this researches are no considering user's situation and preference. Therefore in this paper, we suggest the personalized resource sharing system considering user's situation and preference. Our system is aware of user's situation by using user's schedule information and a context information such as the time and location information and recommends personalized resources by using the simple weighted scheme. We prove our situation-aware based personalized resource sharing system by using a meeting scenario.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.4
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• pp.15-24
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• 2019

Currently, museums and architectural heritage provide augmented user experiences by incorporating various media technologies. They still, however, suffer from the limitation of entertainment-based and the provision of location-based simple and repetitive contents. In addition, while acting as a key medium of experience for architectural heritage, the concept of space is not properly reflected in current services. The purpose of this study is to design user space experience considering such characteristics of architectural heritage. The spatial experience content and content production platform are defined. This software platform creates content that enhances the experience of the place by giving a context-based digital data associated with space and objects. The spatial experience content is designed as a series of experience sequences. The composition of the sequence borrows the method of film and narrative which segment and connect consecutive experiences on a scene basis considering user's detailed spatial experience. Therefore, content components can be combined and reproduced in various types. Augmented contents were extracted by using rule-based reasoning function of ontology at the moment. As a practical example of architectural heritage, the Seokjojeon Hall is used to reveal a spatial experience scenario.

• Journal of Information Processing Systems
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• v.17 no.3
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• pp.615-629
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• 2021

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.

• International Journal of Computer Science & Network Security
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• v.21 no.1
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• pp.125-136
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• 2021

The development of systems that can generate automatically instructional material is a challenging goal for the e-learning community. These systems pave the way towards large scale e-learning deployment as they produce instruction on-demand for users requesting to learn about any topic, anywhere and anytime. However, realizing such systems is possible with the availability of vast repositories of web information in different formats that can be searched, reused and integrated into information-rich environments for interactive learning. This paradigm of learning relieves instructors from the tedious authoring task, making them focusing more on the design and quality of instruction. This paper presents a mobile learning system (Mole) that supports the generation of instructional material in M-Learning (Mobile Learning) contexts, by reusing and integrating heterogeneous hypermedia web resources. Mole uses open hypermedia repositories to build a Learning Web and to generate learning objects including various hypermedia resources that are adapted to the user context. Learning is delivered through a nice graphical user interface allowing the user to navigate conveniently while building their own learning path. A test case scenario illustrating Mole is presented along with a system evaluation which shows that in 90% of the cases Mole was able to generate learning objects that are related to the user query.

• IEMEK Journal of Embedded Systems and Applications
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• v.18 no.4
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• pp.141-150
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• 2023

Currently, various companies are actively participating in research and development of drone delivery services. Existing studies do not comprehensively provide integrated functions for future drone delivery services such as mission automation, customer verification, and overcoming performance limitations, which can lead to high manpower demand, reduced user service trust, and potentially overloading low-end devices. Therefore, this study proposes a drone mission automation system (DMAS) using EdgeCPS technology to provide the three aforementioned functions in an integrated manner. Real-world experiments were conducted to evaluate the proposed system, demonstrating that the DMAS components operate according to the specified roles in the delivery scenario. In addition, the system achieved user verification with a similarity of more than 90% in the process of receiving the product, and verified a faster inference speed and a lower resource share than the existing method.

• KNOM Review
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• v.24 no.1
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• pp.20-28
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• 2021

Extensive use of social media applications and mobile devices continues to increase data traffic. Social media applications generate an endless and massive amount of multimedia traffic, specifically video traffic. Many social media platforms such as YouTube, Daily Motion, and Netflix generate endless video traffic. On these platforms, only a few popular videos are requested many times as compared to other videos. These popular videos should be cached in the user vicinity to meet continuous user demands. MEC has emerged as an essential paradigm for handling consistent user demand and caching videos in user proximity. The problem is to understand how user demand pattern varies with time. This paper analyzes three publicly available datasets, MovieLens 20M, MovieLens 100K, and The Movies Dataset, to find the user request pattern over time. We find hourly, daily, monthly, and yearly trends of all the datasets. Our resulted pattern could be used in other research while generating and analyzing the user request pattern in MEC-based video caching scenarios.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.343-346
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• 1998

This paper present an access scenario to the Korean standard time service systems and those of world major cities was designed in the research for development of the time-announcing service systems. Elements of the system structure as well as statistics and user management were proposed as the main topics for the research. As a result of the research, a system was realized for world time announcing service by dialing 116.

• Information and Communications Magazine
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• v.29 no.7
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• pp.56-61
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• 2012

UX 디자인을 하는데 있어서 제품이나 서비스를 대하는 사용자의 컨텍스트(Context)를 파악하는 것은 매우 중요한 일이다. 다양한 사용자 리서치 방법들 가운데 사용자의 컨텍스트를 파악하기 위한 방법으로는 Contextual Inquiry, 사용자 관찰, Cultural Probes, Contextmapping등이 있는데, 사용자의 컨텍스트는 매우 역동적이고 상황에 따라 다양하게 표현될 수 있으므로 이러한 방법들을 적절하게 조합하여 사용하는 것 이 필요하다. 이렇게 파악된 사용자의 행동패턴과 컨텍스트 요소를 반영하여 UX모델을 만드는데, 사용자의 목표와 사용행태를 기술하는 퍼소나(Persona)가 대표적인 방법이다, 또한 퍼소나를 기반으로 제품이나 서비스에 대한 아이디어와 디자인을 이끌어 내는데 활용하는 '사용자 시나리오(User Scenario)'는 미래의 혁신적인 사용자 경험을 제안하기 위한 유용한 방법이다.

• International Journal of Contents
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• v.7 no.1
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• pp.29-36
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• 2011

Gestures have been employed for human computer interaction to build more natural interface in new computational environments. In this paper, we describe our approach to develop a gesture interface using spatial context information. The proposed gesture interface recognizes a system action (e.g. commands) by integrating gesture information with spatial context information within a probabilistic framework. Two ontologies of spatial contexts are introduced based on the spatial information of gestures: gesture volume and gesture target. Prototype applications are developed using a smart environment scenario that a user can interact with digital information embedded to physical objects using gestures.