• ICROS
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• v.1 no.1
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• pp.66-73
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• 1995

이 글에서는 한국이동통신의 연구개발분야 중에서 차세대서비스로 등장할 주요분야들, 즉 PCS, 무선테이터, advanced paging system, 무선멀티미디어, 저궤도위성통신 등의 기술개발 현황에 대해 소개하고자 한다.

• The Transactions of the Korea Information Processing Society
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• v.3 no.5
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• pp.1179-1186
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• 1996

A previous location area scheme was proposed for cellular network, in which the size of location area of a user is dynamically determined by is current mobility and call arrival rate as the burden of system reaches the minimum. This scheme, however, doesn't consider other individual's movement pattern respectively because of allocating location area with a system's fixed pattern. When mobile subscribers move fast, this scheme allocates especially so large location area to reduce the number of location registration that it makes much paging cost. In this paper, we suggest new dynamic location area management which allocates location area according to each subscriber's mobility regarding its current location as center point. This new scheme allocates fast subscriber larger location area, which resulted in reducing the number of location registration. And small area paging reduces paging cost.

• Korean Management Science Review
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• v.26 no.3
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• pp.23-35
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• 2009

This study deals with the location management in WCDMA (Wideband Code Division Multiple Access) networks. The new location management method is the one of the many techniques used to provide the packet switched (PS) services effectively in WCDMA networks. WCDMA introduces RA (routing area) for the PS services in addition to LA (location area) for the circuit switched (CS) services. WCDMA system also adopts the cooperative paging and the combined area update which are to decrease signaling traffic using the PS network resources for the CS services. Considering the characteristics of the WCDMA networks, this study formulate into the mathematical programming problem for the location management. Rather than the existing researches which consider the single MSC/SGSN networks, we deal with the multi MSC/SGSN networks, where both MSC area and SGSN area should be determined as well. Fairness between traffic loads of MSC/SGSN and the system cost incurred to MSC/SGSN are also incorporated into our model, which make the model more realistic. We propose greedy algorithms for the problems, which consists of the merger of two neighboring areas and the movement of an area. Extensive experiment has been done based on the realistic problem examples. Followed by the analysis of parameter effect on the final solutions and the quality of final solutions obtained by our greedy algorithms. Our proposed model and analysis result can be used to determine WCDMA system areas and to predict the system performance measures by the determination.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.5
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• pp.1-8
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• 2010

Recently subscribers in mobile communication services increase gradually, and the new multifunctional portable terminals can provide various functionalities. However this trend may not be desirable in Green IT respect because the emission of carbon dioxides emitted during operations of base station and mobile stations can cause significant effect on the emissions of carbon dioxides. In this paper the power saving scheme which can adjust slot index while the system is in a paging phase has been proposed and its performance has been evaluated. The slot cycle index can be adjusted according to individual user's property, its effect on the system performance has been investigated. In order to mitigate its adverse effect, power ramping scheme is considered and evaluated thereafter.

• Journal of the Korea Society of Computer and Information
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• v.22 no.12
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• pp.109-116
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• 2017

Short-lived pseudonym certificates as vehicle identities could satisfy both security and privacy requirements. However, to remove revoked certificates especially in vehicle communications, pseudonym certificate revocation list (CRL) should be distributed resource-efficiently from a practical deployment point of view and in a timely manner. In this paper, we propose a novel CRL distribution scheme capable of CRL multicast to only activated vehicles registered to the CRL multicast group using the group communication system enabler, namely, the GCSE which is being standardized. The scheme is resource efficient by using CRL distribution paths instead of paging processes to find out multicast vehicle(s) within a certain region. The analyzed results show that the proposed scheme outperforms in terms of paging cost, packets transmission cost, and the processing cost at the respective entities compared to the existing four schemes in the literature.

• International journal of advanced smart convergence
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• v.12 no.1
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• pp.70-75
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• 2023

With the recent proliferation of memory-intensive workloads such as deep learning, analyzing memory access characteristics for efficient memory management is becoming increasingly important. Since read and write operations in memory access have different characteristics, an efficient memory management policy should take into accountthe characteristics of thesetwo operationsseparately. Although some previous studies have considered the different characteristics of reads and writes, they require a modified hardware architecture supporting read bits and write bits. Unlike previous approaches, we propose a software-based management policy under the existing memory architecture for considering read/write characteristics. The proposed policy logically partitions memory space into the read/write area and the write area by making use of reference bits and dirty bits provided in modern paging systems. Simulation experiments with memory access traces show that our approach performs better than the CLOCK algorithm by 23% on average, and the effect is similar to the previous policy with hardware support.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.527-527
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• 2006

• Journal of Korea Multimedia Society
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• v.10 no.5
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• pp.583-593
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• 2007

We study the page replacement algorithms for demand paging, called CFLRU/C, CFLRU/E and DL-CFLRU/E, that reduce the number of erase operations and improve the wear-leveling degree of flash memory. Under the CFLRU/C and CFLRU/E algorithms, the victim page is the least recently used dean page within the pre-specified window. However, when there is not any dean page within the window, the CFLRU/C evicts the dirty page with the lowest frequency while the CFLRU/E evicts the dirty page with the highest number of erase operations. The DL-CFLRU/E algorithm maintains two page lists called the dean page list and the dirty page list, and first finds the page within the dean page list when it selects a victim. However, when it can not find any dean page within the dean page list, it evicts the dirty page with the highest number of erase operations within the window of the dirty page list. In this thesis, we show through simulation that the proposed schemes reduce the number of erase operations and improve the wear-leveling than the existing schemes like LRU.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.1
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• pp.1-6
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• 2020

Fast service access involves keeping track of the location of mobile users, while they are moving around the mobile network for a satisfactory level of QoS (Quality of Service) in a cost-effective manner. The location databases are used to keep track of Mobile Terminals (MT) so that incoming calls can be directed to requested mobile terminals at all times. MT reporting cell system used in location management is to designate each cell in the network as a reporting cell or a non-reporting cell. Determination of an optimal number of reporting cells (or reporting cell configuration) for a given network is reporting cell planning (RCP) problem. This is a difficult combinatorial optimization problem which has an exponential complexity. We can see that a cell in a network is either a reporting cell or a non-reporting cell. Hence, for a given network with N cells, the number of possible solutions is 2^N. We propose a biogeography based optimization (BBO) for design of mobile station location management system in wireless communication network. The number and locations of reporting cells should be determined to balance the registration for location update and paging operations for search the mobile stations to minimize the cost of system. Experimental results show that our proposed BBO is a fairly effective and competitive approach with respect to solution quality for optimally designing location management system because BBO is suitable for combinatorial optimization and multi-functional problems.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.10
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• pp.26-36
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• 2000

In this paper, we design the nonoverlapping multicarrier modulation (MCM) system for high rate paging system and evaluate the Performance by computer simulation. In conventional paging system, FSK was usually used, but we select QAM for high bandwidth efficiency. Transmitter structure adopts that of 4-16QAM of the iDEN$\^$TM/ and receiver consists of symbol timing recovery, carrier recovery and automatic gain control. In addition, pilot symbol aided modulation (PSAM) which can overcome the simulcast fading channel is considered and we also propose the optimum pilot symbol pattern. Finally, we show the performance of the overall 4-16QAM system by computer simulation.