• Journal of Information Processing Systems
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• 제5권3호
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• pp.151-158
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• 2009

This paper proposes a utility-based data rate allocation algorithm to provide high-quality mobile video streaming over femtocell networks. We first derive a utility function to calculate the optimal data rates for maximizing the aggregate utilities of all mobile users in the femtocell. The total sum of optimal data rates is limited by the link capacity of the backhaul connections. Furthermore, electromagnetic cross-talk poses a serious problem for the backhaul connections, and its influence passes on to mobile users, as well as causing data rate degradation in the femtocell networks. We also have studied a fixed margin iterative water-filling algorithm to achieve the target data rate of each backhaul connection as a counter-measure to the cross-talk problem. The results of our simulation show that the algorithm is capable of minimizing the transmission power of backhaul connections while guaranteeing a high overall quality of service for all users of the same binder. In particular, it can provide the target data rate required to maximize user satisfaction with the mobile video streaming service over the femtocell networks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권9호
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• pp.4188-4206
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• 2016

Power control is widely used to reduce co-channel interference in wireless networks and guarantee the signal-to-interference plus noise ratio (SINR) of ongoing connections. This technique is also effective for wireless body area networks (WBANs). Although achieving satisfactory SINR is important for WBAN users, they may not be willing to achieve it at arbitrarily high power levels since power is a scarce resource in WBANs. Besides, for WBANs with different purposes, the QoS requirements and concern about the power consumption may be different. This motivates us to formulate the power control problem using the concepts from microeconomics and game theory. In this paper, the QoS objective is viewed as a utility function, which represents the degree of user satisfaction, while the power consumption is viewed as a cost function. The power control problem consequently becomes a non-cooperative multiplayer game, in which each player tries to maximize its net utility, i.e., the utility minus the cost. Within this framework, we investigate the Nash equilibrium existence and uniqueness in the game and derive the best response solution to reach the Nash equilibrium. To obtain the optimal transmission power in a distributed way, we further propose a utility-based and QoS-aware power control algorithm (UQoS-PCA). Tunable cost coefficient in UQoS-PCA enables this scheme to be flexible to satisfy diverse service requirements. Simulation results show the convergence and effectiveness of the proposed scheme as well as improvements over existing algorithm.

• Journal of Korean Tunnelling and Underground Space Association
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• 제19권1호
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• pp.11-27
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• 2017

The road network system of major domestic urban areas such as city of Seoul was rapidly developed and regionally expanded. In addition, many kinds of life-lines such as electrical cables, telephone cables, water&sewerage lines, heat&cold conduits and gas lines were needed in order for urban residents to live comfortably. Therefore, most of the life-lines were individually buried in underground and individually managed. The utility tunnel is defined as the urban planning facilities for commonly installing life-lines in the National Land Planning Act. Expectation effectiveness of urban utility tunnels is reducing repeated excavation of roads, improvement of urban landscape; road pavement durability; driving performance and traffic flow. It can also be expected that ensuring disaster safety for earthquakes and sinkholes, smart-grind and electric vehicle supply, rapid response to changes in future living environment and etc. Therefore, necessity of urban utility tunnels has recently increased. However, all of the constructed utility tunnels are cut-and-cover tunnels domestically, which is included in development of new-town areas. Since urban areas can not accommodate all buried life-lines, it is necessary to study the feasibility assessment system for utility tunnel by urban patterns and capacity optimization for urban utility tunnels. In this study, we break away from the new-town utility tunnels and suggest a quantitative assessment model based on the evaluation index for urban areas. In addition, we also develop a program that can implement a quantitative evaluation system by subdividing the feasibility assessment system of urban patterns. Ultimately, this study can contribute to be activated the urban utility tunnel.

• KEPCO Journal on Electric Power and Energy
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• 제8권2호
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• pp.159-179
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• 2022

Often a network becomes complex, and multiple entities would get in charge of managing part of the whole network. An example is a utility grid. While the entire grid would go under a single utility company's responsibility, the network is often split into multiple subsections. Subsequently, each subsection would be given as the responsibility area to the corresponding sub-organization in the utility company. The issue of how to make subsystems of adequate size and minimum number of interconnections between subsystems becomes more critical, especially in real-time simulations. Because the computation capability limit of a single computation unit, regardless of whether it is a high-speed conventional CPU core or an FPGA computational engine, it comes with a maximum limit that can be completed within a given amount of execution time. The issue becomes worsened in real time simulation, in which the computation needs to be in precise synchronization with the real-world clock. When the subject of the computation allows for a longer execution time, i.e., a larger time step size, a larger portion of the network can be put on a computation unit. This translates into a larger margin of the difference between the worst and the best. In other words, even though the worst (or the largest) computational burden is orders of magnitude larger than the best (or the smallest) computational burden, all the necessary computation can still be completed within the given amount of time. However, the requirement of real-time makes the margin much smaller. In other words, the difference between the worst and the best should be as small as possible in order to ensure the even distribution of the computational load. Besides, data exchange/communication is essential in parallel computation, affecting the overall performance. However, the exchange of data takes time. Therefore, the corresponding consideration needs to be with the computational load distribution among multiple calculation units. If it turns out in a satisfactory way, such distribution will raise the possibility of completing the necessary computation in a given amount of time, which might come down in the level of microsecond order. This paper presents an effective way to split a given electrical network, according to multiple criteria, for the purpose of distributing the entire computational load into a set of even (or close to even) sized computational loads. Based on the proposed system splitting method, heavy computation burdens of large-scale electrical networks can be distributed to multiple calculation units, such as an RTDS real time simulator, achieving either more efficient usage of the calculation units, a reduction of the necessary size of the simulation time step, or both.

• International Journal of Internet, Broadcasting and Communication
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• 제16권2호
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• pp.149-160
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• 2024

For examining Web3.0 video streaming (VS) platforms in terms of the decentralized technology, tokenization and decentralized autonomous organization (DAO), we look at four platforms like DLive, DTube, Livepeer, and Theta Network (Theta). As a result, DLive which firstly partnered with Medianova for CDN and with Theta for peer to peer (P2P) network and migrates to Tron blockchain (BC), receives no commission from what creators earn, gives rewards to viewers by measuring engagement, and incentivizes participation by allowing 20% of donation & fees for funding development, 5% to BitTorrent Token (BTT) stakeholders (among these 5%, 20% to partners, 80% to other BTT stakeholders). DTube on its own lower-layer BC, Avalon, offers InterPlanetary File System (IPFS), gives 90% of the created value to creators or curators, and try to empower the community. Livepeer on Ethereum BC offers decentralized CDN, P2P, gives Livepeer Token (LPT) as incentive for network participants, and delegators can stake their LPT to orchestrators doing good. Theta on its native BC pulls streams from peering caching nodes, creates P2P network, gives Theta utility token, TFUEL for caching or relay nodes contributors, and allows Theta governance token, THETA as staking token. We contribute to the categorization of Web3.0 VS platforms: DLive and DTube reduce the risk of platform censorship, promote the diverse content, and allow the community to lead to more user-friendly environments. On the other hand, Livepeer and Theta provide new methods to stream content, but they have some differences. Whereas Livepeer focuses on the transcoding layer, Theta concentrates both on the video application layer and content delivery layer. It means, Theta tries to deliver value to all participants by enhancing network quality, reducing CDN cost, and rewarding users in utility tokens for the storage and bandwidth they provide.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권12호
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• pp.3135-3148
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• 2013

The popularization of streaming networks and mobile devices brings a new kind of network called mobile peer-assisted streaming network. In this network, service provider not only offers downloading services, but also pre-pushes resources to users for caching. Users can download their demanded resources while working as servers for uploading the cached data. Also the mobile characteristic makes high package losing probability in this network. So we study how the service provider pre-pushes or the user downloads resources efficiently and effectively while considering the package losing in this paper. We build utility models for service provider and user, and solve the models using Bellman's theory to achieve Nash Equilibrium which shows the service provider's optimal pre-pushing speed and user's optimal downloading speed. The numerical simulation demonstrates the efficiency and effectiveness of our proposed pre-pushing and downloading scheme by comparing to the traditional scheme.

• Korean System Dynamics Review
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• 제1권2호
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• pp.61-89
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• 2000

The purpose of this study is first, to find out what factors affect the cooperation and trust within the functions in the policy implementation network and in what mechanism these factors interact, second to investigate the whys to manage trust and cooperation successfully in the dynamic situation such as the network setting. For these purpose, this study reviews the concept and characteristics of policy implementation organizations, second, extracts the various factors affecting trust and cooperation in the network situation, third applies and analyzes the relationship among factors to system dynamics model based on the game theory. The results of this study could be summarized as follows: It was found that the utility change within the participants by persuasion ＆ mutual understanding and change of rule would be leading to success in policy implementation network. Also bureaucratic management such as power enforcement does not have any good impact in the managing network. In this study, system simulation method tried to analyze the hypothesis. Quantitative and case analyses were not accompanied and analysis was limited to two-person game theory. So there is some doubt this results could be generalized to actual situation which is N-person game.

• International Journal of Computer Science & Network Security
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• 제22권7호
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• pp.199-205
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• 2022

The extensive growth in data rate demand by the smart gadgets and mobile broadband application services in wireless cellular networks. To achieve higher data rate demand which leads to aggressive frequency reuse to improve network capacity at the price of Inter Cell Interference (ICI). Fractional Frequency Reuse (FFR) has been recognized as an effective scheme to get a higher data rate and mitigate ICI for perfect geometry network scenarios. In, an irregular geometric multicellular network, ICI mitigation is a challenging issue. The purpose of this paper is to develop distributed dynamic power allocation scheme for FFR based on game theory to mitigate ICI. In the proposed scheme, each cell region in an irregular multicellular scenario adopts a self-less behavior instead of selfish behavior to improve the overall utility function. This proposed scheme improves the overall data rate and mitigates ICI.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.613-618
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• 1986

In this study a s/w system(HENSPIN) for the automatic synthesis of HEN(heat exchanger network) was developed based on Pinch Design Method. The synthesized HEN by HENSPIN are satisfying performance targets such as minimum utility usage with as few as possible capital items. The invented network is near optimal in capital and operating cost. It will be used as initial structure for evolution to the structure which has optimal operability.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• 제10권1호
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• pp.1-6
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• 2011

The Underground pipeline facility is a general but most important facility in modern world, but its maintainability has been left behind. An automated and intelligent management technology is needed to prevent the wast of social resource and security. In this paper, we introduce Pipeline Health Monitoring(PHM) with Ubiquitous Sensor Network(USN) for inexpensive structure safety monitoring system, and improve its utility by inventing the advanced impedance converter.