• 한국유기농업학회지
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• 제30권2호
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• pp.129-149
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• 2022

In March 2020, the National Assembly revised the Framework Act on Cooperatives, allowing a federation of heterogeneous cooperatives, and in October 2020, the Daegu Gyeongbuk Federation of Local Food Cooperatives was launched as the first federation of heterogeneous cooperatives in the country. The local food movement, which has been promoted upward in the local community as an alternative to the existing global food system, seems to be being activated by the government's food plan policy, but critics say that the government's policy goals are not fully achieved due to the top-down policy promotion and lack of communication. In response, this study first examines the role and significance of the local food federation of heterogeneous cooperatives in solving the problems raised in the process of establishing a food plan. In addition, the current status of the federation was investigated for the successful settlement and development of the Daegu Gyeongbuk Federation of Local Food Cooperatives. A survey of affiliated cooperatives, focus group interviews with managers and experts and related literature surveys were conducted. Based on this, the direction of activities was presented, such as the role of an intermediary in Daegu and Gyeongbuk and the role of an intermediary in the public and private sectors etc. In addition, six joint project tasks were specifically presented, including an integrated information sharing system & a logistics network, a planned production system & a joint processing center, an online sales system & a co-marketing promotion, a joint education system, a management of direct stores & restaurants, a sustainable public-private cooperation system etc.

• 한국통신학회논문지
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• 제39A권1호
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• pp.62-64
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• 2014

본 논문에서는 이종망 환경에서 펨토셀에 전력제어를 적용하면서도 매크로셀 단말이 받는 간섭의 영향을 완화하도록 펨토셀에 ABSF(Almost Blank Subframes)를 추가적으로 적용하는 경우의 성능을 분석하였다. 모의실험을 통해 제안하는 방법으로 펨토셀의 용량 증대 등 설치 목적은 달성하면서도 매크로셀 단말에 미치는 간섭의 영향을 크게 줄일 수 있음을 확인하였다. 단, 전체 네트워크의 용량은 가능한 최대 용량에 비해 소폭 감소하였다.

• Journal of Communications and Networks
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• 제13권4호
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• pp.360-366
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• 2011

In this paper, we investigate the problem of power allocation in a heterogeneous network that is composed of a pair of cognitive users (CUs) and an infrastructure-based primary network. Since CUs have only limited effective spectrum-sensing ability and primary users (PUs) are not active all the time in all locations and licensed bands, we set up a new multi-area model to characterize the heterogeneous network. A novel combined interference-avoidance policy corresponding to different PU-appearance situations is introduced to protect the primary network from unacceptable disturbance and to increase the spectrum secondary-reuse efficiency. We use dual decomposition to transform the original power allocation problem into a two-layer optimization problem. We propose a low-complexity joint power-optimizing method to maximize the transmission rate between CUs, taking into account both the individual power-transmission constraints and the combined interference power constraint of the PUs. Numerical results show that for various values of the system parameters, the proposed joint optimization method with combined PU protection is significantly better than the opportunistic spectrum access mode and other heuristic approaches.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권5호
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• pp.1973-1991
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• 2018

Multimedia applications over wireless networks have been evolving to augmented reality or virtual reality services. However, a rich data size compared to conventional multimedia services causes bandwidth bottlenecks over wireless networks, which is one of the main reasons why those applications are not used widely. To overcome this limitation, bandwidth aggregation techniques, which exploit a multi-path transmission, have been considered to maximize link utilization. Currently, most of the conventional researches have been focusing on the user end problems to improve the quality of service (QoS) through optimal load distribution. In this paper, we address the joint pricing and load distribution problem for multi-homing in heterogeneous wireless access networks (ANs), considering the interests of both the users and the service providers. Specifically, we consider profit from resource allocation and cost of power consumption expenditure for operation as an utility of each service provider. Here, users decide how much to request the resource and how to split the resource over heterogeneous wireless ANs to minimize their cost while supporting the required QoS. Then, service providers compete with each other by setting the price to maximize their utilities over user reactions. We study the behaviors of users and service providers by analyzing their hierarchical decision-making process as a multileader-, multifollower Stackelberg game. We show that both the user and service provider strategies are closed form solutions. Finally, we discuss how the proposed scheme is well converged to equilibrium points.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2496-2512
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• 2021

The requirements for powerful computing capability, high capacity, low latency and low energy consumption of emerging services, pose severe challenges to the fifth-generation (5G) network. As a promising paradigm, mobile edge networks can provide services in proximity to users by deploying computing components and cache at the edge, which can effectively decrease service delay. However, the coexistence of heterogeneous services and the sharing of limited resources lead to the competition between various services for multiple resources. This paper considers two typical heterogeneous services: computing services and content delivery services, in order to properly configure resources, it is crucial to develop an effective offloading and caching strategies. Considering the high energy consumption of 5G base stations, this paper considers the hybrid energy supply model of traditional power grid and green energy. Therefore, it is necessary to design a reasonable association mechanism which can allocate more service load to base stations rich in green energy to improve the utilization of green energy. This paper formed the joint optimization problem of computing offloading, caching and resource allocation for heterogeneous services with the objective of minimizing the on-grid power consumption under the constraints of limited resources and QoS guarantee. Since the joint optimization problem is a mixed integer nonlinear programming problem that is impossible to solve, this paper uses deep reinforcement learning method to learn the optimal strategy through a lot of training. Extensive simulation experiments show that compared with other schemes, the proposed scheme can allocate resources to heterogeneous service according to the green energy distribution which can effectively reduce the traditional energy consumption.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권10호
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• pp.4680-4697
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• 2017

In future, since the user experience plays a more and more important role in the development of today's communication systems, quality of experience (QoE) becomes a widely used metric, which reflects the subjective experience of end users for wireless service. In addition, the energy efficiency is an increasingly important problem with the explosive growth in the amount of wireless terminals and nodes. Hence, a QoE-aware energy efficiency maximization based joint user access selection and power allocation approach is proposed to solve the problem. We transform the joint allocation process to an optimization of energy efficiency by establishing an energy efficiency model, and then the optimization problem is solved by chaotic clone immune algorithm (CCIA). Numerical simulation results indicate that the proposed algorithm can efficiently and reliably improve the QoE and ensure high energy efficiency of networks.

• Journal of Communications and Networks
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• 제18권2호
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• pp.150-161
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• 2016

Coordinated multi-point transmission (CoMP) techniques are being touted as enabling technologies for interference mitigation in next generation heterogeneous wireless networks (HetNets). In this paper, we present a comparative performance study of uplink (UL) CoMP algorithms for the 3GPP LTE HetNets. Focusing on a distributed and functionally-split architecture, we consider six distinct UL-CoMP algorithms: 1. Joint reception in the frequency-domain (JRFD) 2. Two-stage equalization (TSEQ) 3. Log-likelihood ratio exchange (LLR-E) 4. Symmetric TSEQ (S-TSEQ) 5. Transport block selection diversity (TBSD) 6. Coordinated scheduling with adaptive interference mitigation (CS-AIM) where JRFD, TSEQ, S-TSEQ, TBSD and CS-AIM are our main contributions in this paper, and quantify their relative performances via the post-processing signal-to-interference-plus-noise ratio distributions.We also compare the CoMP-specific front-haul rate requirements for all the schemes considered in this paper. Our results indicate that, with a linear minimum mean-square error receiver, the JRFD and TSEQ have identical performances, whereas S-TSEQ relaxes the front-haul latency requirements while approaching the performance of TSEQ. Furthermore, in a HetNet environment, we find that CS-AIM provides an attractive alternative to TBSD and LLR-E with a significantly reduced CoMP-specific front-haul rate requirement.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2650-2667
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• 2021

In this paper, we derive the expression of the cache hitting probability with random caching policy and propose the joint optimization algorithm based on difference of convex algorithm (DCA) in the three-tier caching heterogeneous cellular network assisted by macro base stations, helpers and users. Under the constraint of the caching capacity of caching devices, we establish the optimization problem to maximize the cache hitting probability of the network. In order to solve this problem, a convex function is introduced to convert the nonconvex problem to a difference of convex (DC) problem and then we utilize DCA to obtain the optimal caching probability of macro base stations, helpers and users for each content respectively. Simulation results show that when the density of caching devices is relatively low, popular contents should be cached to achieve a good performance. However, when the density of caching devices is relatively high, each content ought to be cached evenly. The algorithm proposed in this paper can achieve the higher cache hitting probability with the same density.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권12호
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• pp.4451-4466
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• 2014

We present joint radio selection and relay scheme that delivers data from a source to a sink in heterogeneous stationary sensor networks consisting of various radio interfaces. The proposed scheme finds the optimal relay nodes and their corresponding radio interfaces that minimize energy consumption throughout the network while satisfying the end-to-end packet deadline requirement. We formulate the problem of routing through radio interface selection into binary integer programs, and obtain the optimal solution by solving with an optimization solver. We examine a trade-off relationship between energy consumption and packet delay based on network level simulations. We show that given the end-to-end deadline requirement, our routing algorithm finds the most energy-efficient routing path and radio interface across mesh hops. We demonstrate that the proposed routing scheme exploits the given packet delivery time to turn into network benefit of reducing energy consumption compared to routing based on single radio interface.

• Clinical and Experimental Pediatrics
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• 제53권11호
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• pp.921-930
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• 2010

Juvenile rheumatoid arthritis (JRA) is the most common rheumatic childhood disease; its onset is before 16 years of age and it persists for at least 6 weeks. JRA encompasses a heterogeneous group of diseases that is classified according to 3 major presentations: oligoarthritis, polyarthritis, and systemic onset diseases. These presentations may originate from the same or different causes that involve interaction with specific immunogenetic predispositions, and result in heterogeneous clinical manifestations. An arthritic joint exhibits cardinal signs of joint inflammation, such as swelling, pain, heat, and loss of function; any joint can be arthritic, but large joints are more frequently affected. Extra-articular manifestations include high fever, skin rash, serositis, and uveitis. The first 2 types of JRA are regarded as T helper 1 (Th1) cell-mediated inflammatory disorders, mainly based on the abundance of activated Th1 cells in the inflamed synovium and the pathogenetic role of proinflammatory cytokines that are mainly produced by Th1 cell-stimulated monocytes. In contrast, the pathogenesis of systemic onset disease differs from that of other types of JRA in several respects, including the lack of association with human leukocyte antigen type and the absence of autoantibodies or autoreactive T cells. Although the precise mechanism that leads to JRA remains unclear, proinflammatory cytokines are thought to be responsible for at least part of the clinical symptoms in all JRA types. The effectiveness of biologic therapy in blocking the action of these cytokines in JRA patients provides strong evidence that they play a fundamental role in JRA inflammation.