• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.6
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• pp.77-82
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• 2012

In this paper, the new location management scheme based on region and movement threshold has been proposed in order to minimize the required cost to handle the resource location management signaling traffics under the wire/wireless convergent networks when the users are moving around the cold and hot regions. In this scheme, the sequential paging is supposed to be performed according to the movement threshold which can be changed in accordance with the number of movements that each mobile user had made while it is moving around the resource regions. With the proposed scheme, the cost of managing the location management traffics and efficient spectrum assignment overhead can be minimized by placing signaling traffics for location managements and also allocating radio spectrum considering individual movement behaviors.

• Journal of the Ergonomics Society of Korea
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• v.32 no.2
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• pp.189-198
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• 2013

Objective: This research was carried out to study the menu type design of instrument cluster IVIS(In Vehicle Information System) for efficient navigation under deconcentrated situations. Background: A driver controls the IVIS menu using the rest of cognitive resources while driving a car. Although a driver controls the IVIS using extra cognition resources, his or her distraction can still cause some safety problems while driving. Menu type design of instrument cluster is absolutely important for safe and efficient navigation. Method: Four menu types including paging, flow, icon, and list type were identified through reviewing the existing IVIS of vehicle and the menu structure of cellular phone. Four menu types were evaluated through experiment. The experiment consisted of primary and secondary task, which the primary task was to simulate a driving and the secondary task was to control an IVIS menu prototype. Task performances, menu type preferences, and eye-movement patterns were measured in this experiment. Results: The result shows that icon type was the best design in aspect of task performance and preference. A clue for next menu item provided a positive effect for efficient menu navigation. It was identified that most of subjects gazed the middle-top area of IVIS screen from eye-movement pattern. Conclusion: A basic design of Instrument Cluster IVIS was proposed considering the result of this study in the final. Application: The results of this study can be effectively used in the design of Instrument Cluster IVIS.

• The Journal of the Acoustical Society of Korea
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• v.13 no.4
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• pp.50-59
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• 1994

The pan-european paging system European Radio MEssage System (ERMES), a new system of digital information communication, has 16 channels with 25KHz channel spacing. The ERMES modulation format is 4-PAM/FM. The ERMES operates in the frequency range 169.4125MHz$\~$169.8125MHz. In this paper, an ERMES receiving system according to the European Telecommunication Standard Institute(ETSI) specfication with a double error correction capability is designed. The ERMES receiver system is designed with the conventional circuit and its error performance for muitiple signal modulated by the 4-PAM/FM method are analyzed. Since amplitude imbalance among the signal components can impair the system performance when several receivers are operated on the same RF channel simultaneously, the optimal parameters are obtained in designing the radio system. Performance of the proposed receiver system is verified via computer simulation for processing procedure.

• The Journal of the Korea Contents Association
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• v.15 no.4
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• pp.9-16
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• 2015

On modern operating systems such as Linux, virtual memory is a general way to provide a large address space to applications by using main memory and storage devices. Recently, storage devices have been improved in terms of latency and bandwidth, and it is expected that applications with large memory show high-performance if next-generation storage devices are considered. However, due to the overhead of virtual memory subsystem, the paging system can not exploit the performance of next-generation storage devices. In this study, we propose several optimization techniques to extend memory with next-generation storage devices. The techniques are to allocate block addresses of storage devices for write-back operations as well as to configure the system parameters, and we implement the techniques on Linux 3.14.3. Our evaluation through using multiple benchmarks shows that our system has 3 times (/24%) better performance on average than the baseline system in the micro(/macro)-benchmark.

• Journal of Communications and Networks
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• v.2 no.1
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• pp.5-17
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• 2000

cdma2000 offers several enhancement as compared to TIA/EIA-95, although it remains fully compatible with TIA/EIA-95 systems and allows for a smooth migration from one to the other-Major new capability include:1)connectivity to GSM-MAP in addition to IP and IS-41 networks; 2) new layering with new LAC and MAC architectures for improved service multiplexing and QoS management and efficient use of radio resource ;3) new bands and band widths of operation in support of various operator need and constraints, as well as desire for a smooth and progressive migration to cdma 2000; and 4) flexible channel structure in support of multiple services with various QoS and variable transmission rates at up to 1 Mbps per channel and 2 Mbps per user. Given the phenomenal success of wireless services and desire for higher rate wireless services. improved spectrum efficiency was a major design goal in the elaboration of cdma2000. Major capacity enhancing features include; 1) turbo coding for data transmission: 2)fast forward link power control :3) forward link transmit diversity; 4) support of directive antenna transmission techniques; 5) coherent reverse link structure; and 6) enhanced access channel operation. As users increasingly rely on their cell phone at work and at home for voice and data exchange, the stand-by time and operation-time are essential parameters that can influence customer's satisfaction and service utilization. Another major goal of cdma2000 was therefore to enable manufacturers to further optimize power utilization in the terminal. Major battery life enhancing features include; 1) improved reverse link performance (i.e., reduced transmit power per information bit; 2) new common channel structure and operation ;3) quick paging channel operation; 4) reverse link gated transmission ; and 5) new MAC stated for efficient and ubiquitous idle time idle time operation. this article provides additional details on those enhancements. The intent is not to duplicate the detailed cdma2000 radio access network specification, but rather to provide some background on the new features of cdma2000 and on the qualitative improvements as compared to the TIA/EIA-95 based systems. The article is focused on the physical layer structure and associated procedures. It therefore does not cover the MAC, LAC, radio resource management [1], or any other signaling protocols in any detail. We assume some familiarity with the basic CDMA concepts used in TIA/EIA-95.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.6
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• pp.583-591
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• 2000

Caching mechanisms have been studied extensively to buffer the speed gap of hierarchical storages in the context of cache memory, paging system, and buffer management system. As the wide-area distributed environments such as the WWW extend broadly, caching of remote objects becomes more and more important. In the wide-area distributed environments, the cost and the benefit of caching an object is not uniform due to the location of the object; which should be considered in the cache replacement algorithms. For online operation, the time complexity of the replacement algorithm should not be excessive. To date, most replacement algorithms for the wide-area distributed environments do not meet both the non-uniformity of objects and the time complexity constraint. This paper proposes a replacement algorithm which considers the non-uniformity of objects properly; it also allows for an efficient implementation. Trace-driven simulations show that proposed algorithm outperforms existing replacement algorithms.

• The Transactions of the Korea Information Processing Society
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• v.4 no.3
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• pp.649-658
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• 1997

Database management systems(DMBS)using bolatile memory shluld have a recovery function to protect data against system failutes.Recovery requires much overhead in transaction proessing and is one of the great factors that deteriorate the system performance.Recently, there have been a lot of studies on database systems with nonbolatile memory to enhance the performance.A nonbolatile memory called DFeRAM is one of the promising memory devices of the future technology, but this device does not support fine-franularity licking.In this paper, we present a dual plane FeRAM(DFeRAM)architecture to support the fine-granularity locking.We also propose a recovery algorithm for the database system with the DFeRAM based on a shadow paging methed.In order to analze the performance of the proposed algorithm, we present an analytical model and analyze the performance using the moedl.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.3
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• pp.9-17
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• 2000

In this paper we implement computer simulation system of 4FSK signal MODEM using Quadrature detector and analyze overall tranceiver system. We follow the FLEX wireless paging system standards and construct premodulation filter and data frame. We propose an efficient open loop symbol timing recovery algorithm which takes advantage of 128 bit length preamble pattern and also propose a 32 bit UW pattern which Is based on the optimal UW detection method, and excellent aperiodic autocorrelation characteristic. The BER simulation in the fading channel as well as AWGN is performed with BCH coding and Interleaving to the Quadrature detector system and it is shown that a high coding fain occurs in the fading channel rather than AWGN channel.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.3
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• pp.1-8
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• 2000

This paper presents a simulation model of the Quadrature detector to demodulate FSK signal, which is widely used in wireless paging system for its simple hardware implementation and economics of It fabrication. Quadrature detecter has nonlinear phase characteristic for changes linear changes of input signal frequency. So until now Quadrature detector system analysis remained a difficult problem and performance analysis has not been carried out adequately On these backgrounds, this paper presents the FSK signal demodulation process using Quadrature detector and optimal performance derived from digital simulation technique. First, PSN(Phase Shift Network) which is composed of analog RLC tank circuit is transformed into its equivalent digital transfer function using First-order-hold theorem. Though the demodulated outputs of the Quadrature detector for 4FSK are 4-level signals, only 2 comparators are used and it is shown that optimal performance can be obtained by choosing operation parameter Q value and threshold level decision which are proposed herein.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1B
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• pp.1-7
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• 2008

In group location management, when a transportation system(TS) with multiple mobile subscribers(MSs) changes location area(LA), location management is performed by group location registration by TS, instead of individual location registrations by MSs. In previous works, although it is assumed that LA in group location management is the same as that in individual location management, it is not appropriate to assume the same sized LAs since MSs in a TS have different characteristics from MSs which are not in a TS from the aspect of the speed and aggregate call arrival rates. Thus, in this paper, we propose an efficient location management scheme based on individual and group location managements with different sized LAs, and the performance of the proposed scheme is analyzed from the aspect of signaling cost at the wireless interface. Results reveal that the proposed scheme outperforms the conventional scheme by selecting an appropriate sized LA for group location management.