• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.8
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• pp.1549-1560
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• 2009

In the TDMA PON system, the DBA is essential for ONUs to send data efficiently to the upstream. In this paper, we implement a DBA processor for the G-PON OLT with downstream and upstream rate, 2.5 and 1.25 Gbps, respectively, The processor collects bandwidth request messages from ONUs at every cycle time and allocates properly bandwidth to each Alloc-ID with considering priority and fairness for traffics. In the proposed DBA algorithm, one cycle time consists of multiple G-PON frames ($m{\times}125{\mu}s$) for high link efficiency. In particular, the link efficiency is higher because the algorithm adopts a method that an additional overhead is eliminated when an allocated bandwidth is laid between two G-PON frames for an ONU. This enables that the processor flexibly allocates the bandwidth from zero to the maximum link capacity for an ONU. The proposed DBA processor is implemented with the FPGA and shows bandwidth allocating processes for ONUs with logic analyzer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.12
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• pp.1280-1288
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• 2014

In this paper, we use the ECMA-392 standard, the first cognitive radio networks to meet the demand for IT services in the ship. First, we learn about ECMA-392-based network and examine the consideration and the problems for assigning channels to the device. And, we propose a fair channel resource allocation to ensure efficiently channel required by device groups in ECMA-392 MAC protocol. This is a method to reallocate the channels fairly with considering the channel assignment parameters to a new device group and existing device groups. The simulation results show that the proposed scheme improves throughputs compared to the existing one.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.4
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• pp.370-379
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• 2014

Recently, the interest in optical network with multifiber link is continuing to rise since the network traffic has been growing exponentially. However, growing traffic in network leads to increasing the energy consumption of the network equipment. In this paper, we propose a dynamic routing and wavelength assignment (RWA) algorithm based on V-like cost function and layered graph to improve energy efficiency in IP over WDM network with multifiber link. The V-like cost function is used to decide the fiber cost according to the number of used wavelengths. The layered graph with multifiber link is used to select the energy efficient route and wavelength. The proposed RWA algorithm is compared and analyzed with conventional algorithm in view of average power consumption and blocking probability through OPNET modeler.

• Journal of the Korean Society for Railway
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• v.15 no.5
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• pp.524-530
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• 2012

Recently, open access policy to railway operation has been widely discussed. Compared to the case of Korea, European countries have dealt with this topic over a few decades. The competition on railway slots incurs an important technological problem about how to optimally allocate railway slots requested from RUs to them. In other words, the authority should be able to coordinate the timetables requested from RUs in the non-discriminatory manner. Related with the coordination, compared to the other European countries, which have done many studies and experiments especially on auction mechanisms, Korean railway has paid less attention to this topic and there have not been any related studies. Our study analyses the state-of-the-arts about the railway slot allocation especially focusing on the auction mechanisms and the associated optimization problems. And we suggest a new railway slot allocation mechanism and related optimization model reflecting the adjustment within the tolerance and the operational policies between railway undertakings.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.4
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• pp.515-521
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• 2020

Recently, data traffic has exploded due to development of various industries, which causes problems about losing of efficiency and overloaded existing networks. To solve these problems, network slicing, which uses a virtualization technology and provides a network optimized for various services, has received a lot of attention. In this paper, we propose a resource allocation method using credit value. In the method using the clustering technology, an operation for selecting a cluster is performed whenever an allocation request for various services occurs. On the other hand, in the proposed method, the credit value is set by using the residual capacity and balancing so that the slice request can be processed without performing the operation required for cluster selection. To prove proposed method, we perform processing time and balancing simulation. As a result, the processing time and the error factor of the proposed method are reduced by about 13.72% and about 7.96% compared with the clustering method.

• The KIPS Transactions:PartA
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• v.14A no.7
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• pp.443-450
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• 2007

Performance scalability and storage scalability become important in a large scale cluster of wireless internet proxy cache servers. Performance scalability means that the whole performance of the cluster increases linearly according as servers are added. Storage scalability means that the total size of cache storage in the cluster is constant, regardless of the number of cache servers used, if the whole cache data are partitioned and each partition is stored in each server, respectively. The Round-Robin based load balancing method generally used in a large scale server cluster shows the performance scalability but no storage scalability because all the requested URL data need to be stored in each server. The hashing based load balancing method shows storage scalability because all the requested URL data are partitioned and each partition is stored in each server, respectively. but, it shows no performance scalability in case of uneven pattern of client requests or Hot-Spot. In this paper, we propose a novel dynamic hashing method with performance and storage scalability. In a time interval, the proposed scheme keeps to find some of requested URLs allocated to overloaded servers and dynamically reallocate them to other less-loaded servers. We performed experiments using 16 PCs and experimental results show that the proposed method has the performance and storage scalability as different from the existing hashing method.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.10
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• pp.1101-1108
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• 2015

In this paper, to provide a method and system for providing a network separation virtual machine environment. How to provide this virtual machine environment include phase generating necessary virtual resource requirement for the perform of virtual function and transfer to network changing protocol about request of registration virtual resource. For this reason, Registration procedure is to use a virtual machine for a virtual computing resource allocation and separation combined network any time, it became possible between servers and clients, or mobile phone. At any time, it is possible to process the work in the same environment as in a computer to access the Internet.

• The Journal of the Korea Contents Association
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• v.6 no.9
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• pp.9-18
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• 2006

We completed a new cluster system based on WDM by proposing a virtual topology reconfiguration schemes. The key idea of the proposed scheme is to construct a set with the longest chains of requests of connecting nodes which need to be assigned a wavelength. All the sets have no common factor, that is, there is no duplicated link among the requests of connecting. After making the set satisfying this condition, we could assign a wavelength to per corresponding set. We could reconfigure a virtual topology with this scheme collectively. we compared our scheme to existing approaches by the OWns simulation tool. As the results, we gained improved performances, reducing 10% of blocking rate and improving 30% of ADM utilization in terms of the blocking probability and the ADM utilization.

• The Journal of the Korea Contents Association
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• v.8 no.1
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• pp.160-168
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• 2008

We completed a new cluster system based on WDM by proposing virtual topology reconfiguration schemes. The key idea of the proposed scheme Is to construct a set with the longest chains of requests of connecting nodes which need to be assigned a wavelength. All the sets have no common factor, that is, there is no duplicated link among the requests of connecting. After making the set satisfying this condition, we could assign a wavelength to per corresponding set. We could reconfigure a virtual topology with this scheme collectively. we compared our scheme to existing approaches by the OWns simulation tool. As the results, we gained improved performances, reducing 10% of blocking rate and improving 30% of ADM utilization in terms of the blocking probability and the ADM utilization.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.720-726
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• 2009

There are coexisting various kinds of data in the large scale database system, the maintenance problem of freshness of data is emerging important issue that provide correctness and usefulness information to users. Most solution of this problem depends on how execute effectively required refreshing query within timely time. In this paper, we propose the refreshing scheduling algorithm to retain the freshness of data and fairness of starvation of requested refresh queries. Our algorithm recompute a rate of goal refreshing a every period to assign execution time of requested refreshing query so that we can keep the freshness and fairness of data by using proposed algorithm. We implement the web sites to showing the results of refreshing process of dynamic and semi-dynamic and static data.