• Journal of KIISE
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• v.42 no.1
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• pp.130-137
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• 2015

With the rapid increase of energy consumption and environmental problems, the need for green techniques is increasing. Network coding can provide a solution by reducing unnecessary data transmission and by estimating traffic patterns. In addition, it can amplify the synergy with the cognitive radio network (CR) since the CR has recognition and optimal decision functionalities. In this paper, we propose a network coding based green cognitive radio network. With the simulations, we show that the proposed scheme is up to 25% better than the previous work.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.2
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• pp.550-565
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• 2018

Cognitive radio technology is still the key technology of future mobile communication systems. Previous studies have focused on improving spectrum utilization and less energy consumption. In this paper, we propose an Overhead Reduced Scheme (ORS) for green cooperative spectrum sensing. Compared to traditional cooperative sensing scheme, ORS scheme divides the sensing time into three time slots and selects the best multi-mode user to report decisions. In consideration of reporting channel deviation, we derive closed-form expressions for detection probability and false alarm probability of ORS scheme based on Rayleigh fading channel. Simulation results show that ORS scheme can improve the perception accuracy while reducing the perceived delay and energy consumption in the process of perception, so as to realize the green communication.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.3
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• pp.214-227
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• 2022

The successful implementation of green supply chain management(GSCM) practices requires a level of cooperation that can be difficult to conduct. Despite this challenge, limited scholarly attention has been paid to exploring how the implementation of GSCM practices can be effectively facilitated and enhanced through accumulated social capital with suppliers. Based on social capital theory, this study postulates that supplier network characteristics derived from social capital with key suppliers can be critical antecedents of GSCM, which in turn enhances the firm's environmental performance. To test hypotheses, data were collected from 330 firms in 15 countries, and structural equation modeling was employed. Results show that GSCM improves environmental performance, and structural and cognitive social capitals of the supplier network act as antecedents and lead to GSCM implementation.

• 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 Communications and Networks
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• v.18 no.4
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• pp.610-618
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• 2016

A green cognitive radio network (CRN), characterized by base stations (BSs) that conserve energy during sleep periods, is a promising candidate for realizing more efficient spectrum allocation. To improve the spectrum efficiency and achieve greener communication in wireless applications, we consider CRNs with an long term evolution advanced (LTE-A) structure and propose a novel energy-saving strategy. By establishing a type of preemptive priority queueing model with a single vacation, we capture the stochastic behavior of the proposed strategy. Using the method of matrix geometric solutions, we derive the performance measures in terms of the average latency of secondary user (SU) packets and the energy-saving degree of BSs. Furthermore, we provide numerical results to demonstrate the influence of the sleeping parameter on the system performance. Finally, we compare the Nash equilibrium behavior and social optimization behavior of the proposed strategy to present a pricing policy for SU packets.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.2
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• pp.75-93
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• 2010

Seen topographically, Busan is a city that is coastal and hilly. In the city, most parks have been formed around mountain areas that are not so useful. They also are unbalanced in location among different regions of the city. The purpose of this study is to find how to manage urban parks towards green network promotion. For the purpose, this researcher first analyzed physical and environmental characteristics of urban parks located within the main living spheres of Busan. Then, the researcher examined interactive relations between those parks and downtown areas surrounding them to classify types of the parks. In association, the researcher classified the entire of the city into inland and coastal regions. And the researcher examined mountainous and hilly urban parks that were 150 to 300 meters above sea level in the former region and 100 to 150 meters above sea level in the latter. Findings of the study can be summarized as follows. The above examination found that parks of Busan feature physically penetrating and overlapping with downtown areas of the city. How well the green zones of Busan in form of urban park are inter-connective and influential to each other heavily depends on shapes and functions that the downtown areas of the city have. In this study, urban parks of Busan were grouped according to their types and then analyzed. Based on results of the analysis, the researcher tried to find how to increase the utility of another urban parks that are expected to be formed and how to promote so-called the green network that integrates greens. Considering findings of the study, the researcher would make the following suggestions. In case of forming an urban park in a gently sloped green zone which is easily accessible and noticeable, it's important that the park should include a stream to which another green zone is converged or, if the park is located near a costal area, contribute to promote urban functions and openness. While, in a high-altitude green zone, it's more effective to form so-called the green way that consists of some limited usable site of the zone and greens behind it and then form a hub of regional community at the intersection between the main road and main gate to the urban park, contributing to the green network promotion.