• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1995.10a
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• pp.559-562
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• 1995

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.67-74
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• 2020

One of the missions of active-duty units in charge of managing reserve forces is providing combat supplies to reserve forces to exercise their combat capabilities quickly when declaring a mobilization order. Rear area active-duty units must support large local reserve forces. On the other hand, military units have difficulties due to a lack of forces and the storage of large quantities of firearms and ammunition. For this reason, local reserve forces should move to an integrated storing place and receive their firearms and ammunition. The existing distribution plan (existing plan) is a first-in-first-out plan that can produce inconsistent distribution orders. The inconsistent distribution orders can increase the complete distribution time, which will affect the combat power of local reserve forces. Therefore, firearms and ammunition should be distributed quickly. Accordingly, this paper proposes the priority selection of firearms and ammunition for local reserve forces with a minimum complete distribution time using Dynamic Programming. To verify the proposed model, the existing plan was compared with the proposed model using real data, and the result showed that the proposed model outperformed the existing plan.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.729-736
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• 2003

With the rapid growth of the Internet, popular Web sites are visited so frequently that these cannot be constructed with a single server or mirror site of high performance. The rapid increase of Internet uses and uses raised the problems of overweighted transmission traffic and difficult load balancing. To solve these, various schemes of server clustering have been surveyed. Especially, in order to fully utilize the performance of computer systems in a cluster, a good scheduling method that distributes user requests evenly to servers in required. In this paper, we propose a new method for reducing the service latency. In our method, each Web server in the cluster has different content. This helps to reduce the complexity of load balancing algorithm and the service latency The Web server that received a request from the load balancer responds to the client directly without passing through the load balancer. Simulation studies show that our method performs better than other traditional methods. In terms of response time, our method shows shorter latency than RR (Round Robin) and LC (Least Connection) by about 16%, 14% respectively.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.8
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• pp.215-222
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• 2021

In order to alleviate the limited resource problem and interference problem in cellular networks, the dual connectivity technology has been introduced with the cooperation of small cell base stations. In this paper, we design a new efficient and fair resource allocation scheme for the dual connectivity technology. Based on two different bargaining solutions - Generalizing Tempered Aspiration bargaining solution and Gupta and Livne bargaining solution, we develop a two-stage radio resource allocation method. At the first stage, radio resource is divided into two groups, such as real-time and non-real-time data services, by using the Generalizing Tempered Aspiration bargaining solution. At the second stage, the minimum request processing speeds for users in both groups are guaranteed by using the Gupta and Livne bargaining solution. These two-step approach can allocate the 5G radio resource sequentially while maximizing the network system performance. Finally, the performance evaluation confirms that the proposed scheme can get a better performance than other existing protocols in terms of overall system throughput, fairness, and communication failure rate according to an increase in service requests.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8A
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• pp.777-784
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• 2010

Recently, the necessity of underwater communication and demand for transmitting and receiving various data such as voice or high resolution image data are increasing as well. The performance of underwater acoustic communication system is influenced by characteristics of the underwater communication channels. Especially, ISI(inter symbol interference) occurs because of delay spread according to multi-path and communication performance is degraded. In this paper, we study the OFDM technique to overcome the delay spread in underwater channel and by using CP, we compensate for delay spread. But PAPR which OFDM system has problem is very high. Therefore, we use DFT-spread OFDM method to avoid nonlinear distortion by high PAPR and to improve efficiency of amplifier. DFT-spread OFDM technique obtains high PAPR reduction effect because of each parallel data loads to all subcarrier by DFT spread processing before IFFT. In this paper, we show performance about delay spread through OFDM system and verify method that DFT spread OFDM is more suitable than OFDM for underwater communication. And we analyze performance according to two subcarrier mapping methods(Interleaved, Localized). Through the simulation results, performance of DFT spread OFDM is better about 5~6dB at $10^{-4}$ than OFDM. When compared to BER according to subcarrier mapping, Interleaved method is better about 3.5dB at $10^{-4}$ than Localized method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3A
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• pp.184-194
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• 2005

One of the most important factors that decide the overall performance of RFID system is anti-collision algorithm. By enhancing the anti-collision algorithm, we can increase the number of RFID tags that can be processed in unit time. Two anti-collision algorithms are most widely prevailed: one is ALOHA-based protocol and the other is a binary tree walking method, but these are still under research. In this paper, we suggest an anti-collision algorithm named AAC(Address Allocating and Calling) using pre-distributed random address, which is much faster and more efficient than existing ones. Finally, we evaluate our scheme using mathematical analysis and computer simulation.

• Journal of Internet Computing and Services
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• v.6 no.5
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• pp.1-9
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• 2005

In a role based access control through attribute certificate, the use of role assignment certificates and role specification certificates can reduce management cost and the overhead incurred by changing roles, Highly distributed computing environments such as ubiquitous computing environments not having global or broad control. need another attribute certificate management technique, Actually just having role specification certificate separately reduce management cost, But for better performance we structure role specification, We group roles and make the role group relation tree, It results secure and efficient role renewing and distribution, For scalable role specification certificate distribution, the multicasting of packets is used, We take into account the packet lass and quantify performance enhancements of structuring role specification certificates.

• Journal of KIISE:Information Networking
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• v.28 no.3
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• pp.426-434
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• 2001

Striping is a scheme that partitions data into blocks and distributes the blocks on different servers in a well defined order and thus could improve system capacity through load balance. In this paper, we propose a parallel VOD server and striping policies for load balancing when extra storage nodes are attached to a parallel VOD server for insufficient disk space in that VOD server. When new video data is stored on the attached storage node, the node may be overloaded. Since it decreases the system bandwidth, appropriate striping policies are required. We therefore present three striping policies that move some block of data o existing nodes into the new node and distribute the new data across all the storage nodes including the new node. Our experiment result shows that FSM bi-direction is the most effective technique.

• Journal of KIISE
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• v.43 no.11
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• pp.1223-1232
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• 2016

A virtual network technology can provide a network reflecting the requirements of various services. The virtual network can distribute resources of the physical network to each virtual slice. An efficient resource distribution technique is needed to reflect the requirements of various services. Existing bandwidth distribution techniques can only control downlink traffic without taking traffic conditions on the network into account. Downlink and uplink share the same resources in a wireless network. The existing bandwidth distribution techniques assumed that all stations generate saturated traffic. Therefore, the existing bandwidth distribution technique cannot make traffic isolation in a virtual wireless network. In this paper, we proposed a traffic-based bandwidth control techniques to solve these problems. We applied Software-Defined Networking(SDN) to the virtual wireless network, monitored the traffic at each station, and searched for stations that generated unsaturated traffic. We also controlled both uplink and downlink traffics dynamically based on monitoring information. Our system can be implemented with legasy 802.11 clients and SDN-enabled APs. After the actual test bed configuration, it was compared to existing techniques. As a result, the distribution performance of the proposed technique was improved by 14% in maximum.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8C
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• pp.637-644
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• 2012

In this paper, a new compact power divider is suggested. Instead of the quarter wavelength transmission line(TX-line)s for the branches of the conventional Wilkinson's power divider design method, we use our composite right- and left-handed(CRLH) TX-line zeroth order resonator(ZOR) bandpass filters of one twelfth wavelength and reduce the physical length of the power divider. Besides, the filters in the branches can secure the passband for power-division. To validate the proposed power divider, we take an L-band for millitary satellaite transponder as the test case and the performances of the circuit and full-wave simulation results with the CRLH properties of the structure are shown with the dispersion curve and E-field at the ZOR. The measurement is compared with the simulation results. Also, the size reduction effect by the proposed scheme is addressed