• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.9-17
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• 2014

Heterogeneous network (HetNet) is a network consisting of macrocells overlaid with small cells. In HetNet, the interference from macrocell to small cell users is a major cause of performance degradation of small cell users and enhanced inter-cell interference coordination (eICIC) is needed to mitigate the interference. Previous works on eICIC gives limited performance gain because these works focus on maximizing long-term throughput and rarely consider varying channel conditions over frames. This paper proposes a new algorithm which dynamically coordinates interference and schedules users on each frame to maximize the total utility of the network with lower computational complexity than exhaustive search. Simulation results show that the proposed algorithm achieves higher total throughput than the throughput with the conventional algorithm, and has higher fairness index than the conventional algorithm when there large number of users.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.6
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• pp.2709-2734
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• 2020

The growing demand to make wireless data services 5G compatible has necessitated the development of an energy-efficient approach for an effective new wireless environment. In this paper, we first propose a cognitive sensor node (CSN) based game theory for deriving energy via a primary user-transmitted radio frequency signal. Cognitive users' time was segmented into three phases based on a time switching protocol: energy harvest, spectrum sensing and data transmission. The proposed model chooses the optimal energy-harvesting phase as the effected factor. We further propose a distributed energy-harvesting model as a utility function via pricing techniques. The model is a non-cooperative game where players can increase their net benefit in a selfish manner. Here, the price is described as a function pertaining to transmit power, which proves that the proposed energy harvest game includes Nash Equilibrium and is also unique. The best response algorithm is used to achieve the green connection between players. As a result, the results obtained from the proposed model and algorithm show the advantages as well as the effectiveness of the proposed study. Moreover, energy consumption was reduced significantly (12%) compared to the benchmark algorithm because the proposed algorithm succeeded in delivering energy in micro which is much better compared to previous studies. Considering the reduction and improvement in power consumption, we could say the proposed model is suitable for the next wireless environment represented in 5G.

• Journal of Forest and Environmental Science
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• v.24 no.3
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• pp.127-135
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• 2008

The mission of the Forest Inventory and Analyis (FIA) program of the Forest Service, U.S. Department of Agriculture, is to conduct the national forest inventory of the United States of America for purposes of estimating the area of forest land; the volume, growth, and removal of forest resources; and the health of the forest. Users of FIA data, estimates, and related products include land managers, policy and decision-makers, forest industry, environmental organizations, and university researchers. To accomplish its mission, the FIA program has established a sampling design with an intensity of approximately one permanent plot per 2,400 ha across the entire country. Depending on the region of the country, each plot is remeasured at intervals of five or 10 years. The program releases data annually and reports estimates at the county level for each state every five years. Due to budgetary constraints and natural variability among plot observations, sufficient numbers of plots cannot be measured to satisfy precision guidelines for the estimates of many variables unless the estimation process is enhanced using ancillary data. Classified satellite imagery has been demonstrated to be a source of ancillary data that can be used with stratified estimation techniques to increase the precision of estimates with little corresponding increase in costs. A crucial factor restricting the utility of FIA data is that the exact locations of inventory plots cannot be released to the public. Thus, users are generally not able to obtain estimates for small areas or for their own areas of interest if exact plot locations are required. To compensate, satellite imagery, inventory plot data, and the k-Nearest Neighbors technique are being used to construct Internet-based maps of forest attributes from which estimates for arbitrary user-defined areas of interest may be obtained.

• Journal of Intelligence and Information Systems
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• v.17 no.2
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• pp.23-38
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• 2011

Energy management aims to financial and ecological success by optimizing the energy consuming sources such as sensors, computers and appliances. Hence, acquiring energy-related data from the sources in an automated manner is the starting point of managing energy. Recently, awareness computing has been emerging in system and cybernetics area. Awareness is the most fundamental ability for any living things to survive, and also the first step to make systems intelligent with the help of artificial intelligence. Even though the potential reciprocal benefits between energy management and awareness computing, frameworks which show how awareness computing contributes to manage energy-related strategy have been very few. Hence, this paper aims to introduce the awareness computing issues to improve energy management. In particular, we focus on satisfaction awareness computing which potentially realize the balance of energy savings and user's utility.

• The Journal of the Korea Contents Association
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• v.13 no.1
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• pp.19-29
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• 2013

In the current Internet environment where there is high space complexity of information, search engines aim to provide accurate information that users want. But content-based method adopted by most of search engines cannot be used as an effective tool in the current Internet environment. As content-based method gives different weights to each web page using morphological characteristics of vocabulary, the method has its drawbacks of not being effective in distinguishing each web page. To resolve this problem and provide useful information to the users, this paper proposes an evaluation method based on categories. Category-based evaluation method is to extend query to semantic relations and measure the similarity to web pages. In applying weighting to web pages, category-based evaluation method utilizes user response to web page retrieval and categories of query and thus better distinguish web pages. The method proposed in this paper has the advantage of being able to effectively provide the information users want through search engines and the utility of category-based evaluation technique has been confirmed through various experiments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7A
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• pp.560-568
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• 2012

Spectrum sensing and spectrum decision are the main functions that cognitive radios (CRs) have to perform in order to get the best available spectrum band for the establishment of a wireless communication. These problems are worsened in the presence of users with different demands and spectrum channels with different properties in a heterogeneous network. The primary objective in this work is to design and simulate a new spectrum decision algorithm for heterogeneous cognitive radio system. To this end, first, we consider all cognitive users are separated into different traffic classes according to their Quality of Service (QoS). The cognitive users within one traffic class perform spectrum sensing in centralized group-based cooperative spectrum sensing system and the users of different traffic classes share the sensing results. Second, we propose a novel use of the Analytic Hierarchy Process (AHP) to optimally select available bands according to user requirements and detected spectrum channel characteristics (SCC). In this paper, utility function is used as spectrum decision algorithm. Simulation results demonstrate that the proposed method shows can effectively select the best available spectrum channels with a low complexity.

• Journal of Communications and Networks
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• v.16 no.6
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• pp.627-638
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• 2014

In this paper, we study the joint price and power allocation in spectrum sharing macro-femtocell networks. The proposed game theoretic framework is based on bi-level Stackelberg game where macro base station (MBS) works as a leader and underlaid femto base stations (FBSs) work as followers. MBS has fixed data rate and imposes interference price on FBSs for maintaining its data rate and earns revenue while FBSs jointly adjust their power for maximizing their data rates and utility functions. Since the interference from FBSs to macro user equipment is kept under a given threshold and FBSs compete against each other for power allocation, there is a need to determine a power allocation strategy which converges to Stackelberg equilibrium. We consider two cases for MBS power allocation, i.e., fixed and dynamic power. MBS can adjust its power in case of dynamic power allocation according to its minimum data rate requirement and number of FBSs willing to share the spectrum. For both cases we consider uniform and non-uniform pricing where MBS charges same price to all FBSs for uniform pricing and different price to each FBS for non-uniform pricing according to its induced interference. We obtain unique closed form solution for each case if the co-interference at FBSs is assumed fixed. And an iterative algorithm which converges rapidly is also proposed to take into account the effect of co-tier interference on interference price and power allocation strategy. The results are explained with numerical simulation examples which validate the effectiveness of our proposed solutions.

• Journal of KIISE
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• v.43 no.2
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• pp.246-255
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• 2016

The orthogonal frequency-division multiple access (OFDMA) systems are well suited to multi-rate multicast transmission, as they allow flexible resource allocation across both frequency and time, and provide adaptive modulation and coding schemes. Unlike layered video coding, the multiple description coding (MDC) enables flexible decomposition of the raw video stream into two or more substreams. The quality of the video stream is expected to be roughly proportional to data rate sustained by the receiver. This paper describes a mathematical model of resource allocation and throughput in the multi-rate video multicast for the OFDMA wireless and mobile networks. The impact on mean opinion score (MOS), as a measurement of user-perceived quality (by employing a variety of scheduling disciplines) is discussed in terms of utility maximization and proportional fairness. We propose a pruning algorithm to ensure a minimum video quality even for a subset of users at the resource limitation, and show the optimal number of substreams and their rates can sustain.

• Korean Journal of Environment and Ecology
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• v.21 no.2
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• pp.168-175
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• 2007

For maximum utility of trails, there is a need for better knowledge of characteristics of trail use and its users. The purpose of this study is to find out users' attitudes toward trail structures in Eorimok exploring route in Hallasan National Park managerial purposes. A questionnaire survey was conducted to 138 people on the way back home from their visit to the site from July to August, 2007. The geological conditions of 7 types of pedestrian trail structures were rated relatively high both in quantity and quality. The responses were noticeably positive about the natural materials used in wood deck and PP rope railings from the point of three aspects: harmony with nature, visitor convenience and resources conservation. It seems necessary to replace steel structures with native materials because such unnatural materials used in a natural setting are subject to visitor's resistance.

• Journal of Korea Game Society
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• v.17 no.3
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• pp.107-116
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• 2017

Sandbox game users can double their satisfaction by re-creating a variety of play patterns. This creative process is due to the expansion of play through 'customizing' and 'action autonomy'. The purpose of this study is to investigate the structural limitations of freedom of online game. In a standalone game, the scalability due to the degree of freedom gives the user a strong motivation for world persistence. On the other hand, in online sandbox games such as MMORPG, it is confirmed that the goal-oriented tendency to gain advantage is the inherent limit of the freedom and expandability of the sandbox game. In this study, it is suggested that the cause and limit of growth of online-based sandbox game can be offset by the optimal solution factor.