• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.11
• /
• pp.2636-2656
• /
• 2013

To improve the cooperative efficiency of node cooperation and multiple access performance for multihop wireless networks, a priority-differentiated cooperative medium access control protocol with contention resolution (CRP-CMAC) is proposed. In the protocol, the helper selection process is divided into the priority differentiation phase and the contention resolution phase for the helpers with the same priority. A higher priority helper can choose an earlier minislot in the priority differentiation phase to send a busy tone. As a result, the protocol promptly selects all the highest priority helpers. The contention resolution phase of the same priority helpers consists of k round contention resolution procedures. The helpers that had sent the first busy tone and are now sending the longest busy tone can continue to the next round, and then the other helpers that sense the busy tone withdraw from the contention. Therefore, it can select the unique best helper from the highest priority helpers with high probability. A packet piggyback mechanism is also adopted to make the high data rate helper with packet to send transmit its data packets to its recipient without reservation. It can significantly decrease the reservation overhead and effectively improve the cooperation efficiency and channel utilization. Simulation results show that the maximum throughput of CRP-CMAC is 74%, 36.1% and 15% higher than those of the 802.11 DCF, CoopMACA and 2rcMAC protocols in a wireless local area network (WLAN) environment, and 82.6%, 37.6% and 46.3% higher in an ad hoc network environment, respectively.

• Journal of Digital Convergence
• /
• v.18 no.10
• /
• pp.225-232
• /
• 2020

The underlaying communication scheme in 5G cellular network is a very promising resource sharing scheme, and it is an effective scheme for improving service performance of 5G and reducing communication load between a cellular link and a device to device (D2D) link. This paper proposes the algorithm to minimize the resource interference that occurs when performing 5G-based multi-class service on gNB(gNodeB) and the cooperative priority-based resource allocation scheduling scheme (CPRAS) to maximize 5G communication service according to the analyzed control conditions of interference. The proposed CPRAS optimizes communication resources for each device, and it optimizes resource allocation according to the service request required for 5G communication and the current state of the network. In addition, the proposed scheme provides a function to guarantee giga-class service by minimizing resource interference between a cellular link and a D2D link in gNB. The simulation results show that the proposed scheme is better system performance than the Pure cellular and Force cellular schemes. In particular, the higher the priority and the higher the cooperative relationship between UE(User Equipment), the proposed scheme shows the more effective control of the resource interference.

• Journal of Distribution Science
• /
• v.13 no.12
• /
• pp.65-71
• /
• 2015

Purpose - Domestic cooperatives tend to increase during the establishment of cooperatives and gradually through the basic law of social needs. However, only cooperatives' qualitative grow this secured without blessings, and their quantitative growth through government support is questionable. The purpose of this study is to analyze the agricultural cooperatives established through the Distribution System Cooperatives Basic Law, which was enacted in January 2012. Subsequently, establishing agricultural cooperatives was done briskly. However, cooperatives established rapidly after the founding of the Basic Law encountered problems. Research design, data, and methodology - To assess the performance of selected agricultural cooperatives, data were analyzed using the methodological Analytic Hierarchy Process (AHP) approach. The AHP is a set of systematic procedures to hierarchically analyze the elements of any problem. Using a survey on expertise, a series of comparative determinations of each pair is performed to evaluate the relative strengths and the strengths of the impact between elements within the hierarchy. A survey was conducted on 10 small agricultural cooperatives using AHP analysis for the examination. The purpose of such research and analysis is to recommend a direction for future policies aimed at small agricultural cooperatives. Result - This study applied three types of policy evaluation criterion, including market expansions, organizations, and cooperative projects, and 12 types of small agricultural cooperative policy measures. Market expansion policies for agricultural cooperatives are classified into four categories: school meals, direct transactions, shopping malls, and wholesale markets. Organizational policies for agricultural cooperatives are classified into four types: existing sales channel management, education, preventing free riding, and enlarging members. Cooperative project policies in agricultural cooperatives are classified into four policy areas: cooperation between cooperatives, community contribution, joint businesses, and government links. In this paper, the growth priority in agricultural cooperative policies is analyzed by applying policy evaluation criteria on the basis of a survey on expertise. The priorities of the policy program are also analyzed using a decision analytic hierarchy process. The results indicate that market expansion is the most important policy evaluation criterion therefore, improving direct transactions, school meals, management of existing sales channels, and shopping malls are crucial policy measures. In contrast, the cooperation of cooperatives, expansion of union members, and cooperation with the government were found to have low priority. Conclusions - Agricultural cooperatives should develop plans as follows. Small agricultural cooperatives need to secure school meals and direct transactions for market expansion, restructure marketing strategies to manage existing sales channels, and, finally, increase education and training for sustainable organizational development. This study has the following limitations. Because the subject of the investigation is a new cooperative, determining its sustainable growth is difficult. Therefore, through analysis and a continuous study of cooperatives, future research is expected to show that modifying the direction of agriculture cooperatives is necessary.

• Korean Journal of Agricultural Science
• /
• v.43 no.1
• /
• pp.144-151
• /
• 2016

With an aging population in rural areas, farm owners in South Korea are also aging. In particular, this phenomenon leads to the lack of human resources in rural areas and agriculture, worsening the deterioration of the rural economy. This study aimed, firstly, to analyze the criticality of the lack of human resources and high production cost issues for farmers, before using the farm as cooperative nursery of rice seedlings. Secondly, the study analyzed farmer satisfaction after using the farm cooperative. Analysis results are as follows. The motives of the research subjects for using the co-nursery were the aging of the farming population, the expected reduction of production costs, and farmers' failure in raising seedlings. Importance-performance analysis measured the importance for the farms for cooperative raising of rice seedling at 3.49 and the performance for the farms at 3.41, with a difference of 0.07 between them. The four importance-performance matrix areas, used were as follows: concentrated efforts required (Quadrant I: concentrate here), continuous maintenance (Quadrant II: keep up the good work), gradual improvement (Quadrant III: low priority), and avoiding excessive efforts (Quadrant IV: possible overkill). Based on the results, it was concluded that improvements and efforts would be necessary for each of these areas. And, there is a need to improve services through the initiation of farmer use of this rice co-nursery.

• Korean Management Science Review
• /
• v.29 no.2
• /
• pp.21-34
• /
• 2012

This paper addresses a network design problem in a supply chain system that involves locating both plants and distribution centers, and determining the best strategy for distributing products from the suppliers to the plants, from the plants to the distribution centers and from the distribution centers to the customers. This paper suggests a cooperative coevolutionary algorithm (CCEA) approach to solve the model. First, the problem is decomposed into three subproblems for each of which the chromosome population is created correspondingly. Each chromosome in each population is represented as a permutation denoting the priority. Then an algorithm generating a solution from the combined set of chromosomes from each population is suggested. Also an algorithm evaluating the performance of a solution is suggested. An experimental study is carried out. The results show that our CCEA tends to generate better solutions than the previous CCEA as the problem size gets larger and that the permutation representation for chromosome used here is better than other representation.

• Journal of the Korean Home Economics Association
• /
• v.39 no.3
• /
• pp.107-133
• /
• 2001

This study aims to understand the Process of Communality formation among the Families of Communal Childcare Cooperative. Ethnographic, in-depth interview and participant observation at field are used as method. The families of communal childcare cooperative form their communality through investment and harmony, making relationship, and struggles and overcoming the struggles. Each family is willing to put in their money and time for an unfamiliar group to organize and manage a community. They head for the same direction accepting the diversity of expectation and thought based on the diversity of environment of each family. They have interactions upon the basis of equality among the families. Sharing their unique cloture such as communal place(teojeon), common issues, same generation, unique terms, specific modes of speaking informally or nicknaming, they accept the diversities and head for the sameness to have a harmony. In the reset of forming relationship, these families transfer successfully from the field of I and my family to that of group. They escape from a sense of priority that concerns their own family first and then others. They come to be able to consider the group first. Besides, they come to assimilate themselves to the group by identification with the group. They come to form their identity and sense of membership of the group recognizing power of group they belong in their families and local society. The process of forming community among the families of cooperative has inescapable struggles. Each family becomes a real host of the cooperative in the process of overcoming the struggles and experiences a growth of individual and group in the process of looking for the ways of overcoming the struggles. In the end, the families cooperates and reestablish their community.

• Journal of Communications and Networks
• /
• v.16 no.2
• /
• pp.110-120
• /
• 2014

This article proposes a spectrum sharing method which can avoid the mutual interference in both primary and secondary systems. The two systems make them a priority to use two single-dimension orthogonal signals, the real and imaginary pulse amplitude modulation signals, if the primary system is not in outage with this use. A secondary transmitter is selected to be the primary relay and the active secondary source to perform this. This allows a simultaneous spectrum access without any mutual interference. Otherwise, the primary system attempts to use a full two-dimensional signal, the quadrature amplitude modulation signal. If there is no outage with respect to this use, the secondary spectrum access is not allowed. When both of the previous attempts fail, the secondary system is allowed to freely use the spectrum two whole time slots. The analysis and simulation are provided to analyze the outage performance and they validate the considerable improvement of the proposed method as compared to the conventional one.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.5C
• /
• pp.276-285
• /
• 2011

In this paper, we propose new cooperative precoder selection technique for interference limited MIMO networks. Our proposed method gives weighting to precoders in the codebook according to each precoder's performance priority. By applying our proposed method to precoder selection sequence, performance of entire system can be improved in terms of sumrate, stability, and feedback rate.

• Journal of Communications and Networks
• /
• v.16 no.2
• /
• pp.140-145
• /
• 2014

In this paper, we propose an anti-interference cooperative spectrum sharing strategy for cognitive system, in which a secondary system can operate on the same spectrum of a primary system. Specifically, the primary system leases a fraction of its transmission time to the secondary system in exchange for cooperation to achieve the target rate. To gain access to the spectrum of the primary system, the secondary system needs to allocate a fraction of bandwidth to help forward the primary signal. As a reward, the secondary system can use the remaining bandwidth to transmit its own signal. The secondary system uses different bandwidth to transmit the primary and its own signal. Thus, there will be no interference felt at primary and secondary systems. We study the joint optimization of time and bandwidth allocation such that the transmission rate of the secondary system is maximized, while guaranteeing the primary system, as a higher priority, to achieve its target transmission rate. Numerical results show that the secondary system can gain significant improvement with the proposed strategy.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.5
• /
• pp.2177-2193
• /
• 2018

This paper studies resource allocation schemes for the relay-aided cooperative system consisting of multiple source-destination pairs and decode-forward (DF) relays. Specially, relaying selection, multisubcarrier pairing and assignment, and power allocation are investigated jointly. We consider a combinatorial optimization problem on quality of experience (QoE) and energy consumption based on relay-aided cooperative system. For providing better QoE and lower energy consumption we formulate a multi-objective optimization problem to maximize the total mean opinion score (MOS) value and minimize the total power consumption. To this end, we employ the nondominated sorting genetic algorithm version II (NSGA-II) and obtain sets of Pareto optimal solutions. Specially, two formulas are devised for the optimal solutions of the multi-objective optimization problems with and without a service priority constraint. Moreover, simulation results show that the proposed schemes are superior to the existing ones.