• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9A
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• pp.1340-1347
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• 2000

The international mobile telecommunication-2000(IMT-2000) system can support not only the non-realtime multimedia traffic such as data such as data image but also the realtime multimedia traffic such as voice, video. In the paper we propose multicode allocation and handoff schemes for efficient transmission of realtime and non-realtime data in cdma2000. In those schemes the bandwidth of target cell is reserved based on moving direction of mobiles to support QoS of realtime multimedia data and the reserved bandwidths is used by the non-realtime mobiles of the target cell until the mobiles want to perform hadoff. Our framework is able to guarantee QoS continuity of realtime multimedia data and carries the maximum number of subscriber. System performance is evaluated and compared with conventional scheme considering transmission delay channel utilization and blocking probability by computer simulation.

• KIEE International Transactions on Power Engineering
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• v.3A no.2
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• pp.93-99
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• 2003

This paper deals with the development and testing of a large-scale, realtime digital power system simulator for the Korean Electric Power Corporation. The KEPS Simulation Center is located at KEPCO's research center (KEPRI) in Taejon, South Korea and has been operated since September 2001. The KEPS Simulation Center includes a wide range of off line power system simulation and analysis tools, as well as an advanced realtime digital simulator for the study of large scale AC and DC system performance. Because the application scope of the KEPS realtime simulator is broad and because the network models being considered are significantly larger and more complex than in traditional realtime simulator applications, many developments and tests have been required during the course of the project. In this paper, the authors describe some of these developments and present results from various benchmark tests that have been performed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9A
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• pp.736-745
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• 2003

Resource allocation methods are proposed to address the problem of how flexibly allocate limited wireless resource to high bandwidth demanded realtime class with certain QoS guarantees in CDMA/TDD systems. In this method, A reserved access scheme is used for allocating the resource to realtime and non-realtime class respectively. We also propose a slot allocation algorithm for the CDMA/TDD system, which can prevent the performance degradation due to the interlink interference in each cell. Our framework is able to guarantee QoS continuity of realtime class and carry the maximum number of non-realtime subscriber. System performance of proposed method is evaluated by considering transmission delay, channel utilization and data loss, assuming a practical multi-cell environment and a multimedia service model. Our simulation results demonstrate the significant performance improvement.

• Journal of KIISE:Information Networking
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• v.35 no.5
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• pp.425-436
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• 2008

In this paper, we propose a resource effective call admission control(CAC) in integrated WLAN and cellular network. The proposed CAC mitigates the congestion of cellular network by handing over non-realtime traffic to WLAN. We analyze the proposed CAC in numerical and simulation method. The simulation results show that the proposed CAC achieves better performance than normal CAC. Especially, the proposed CAC can sustain desired QoS more robustly against high incoming non-realtime traffic load than againt realtime traffic load.

• The Transactions of the Korea Information Processing Society
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• v.7 no.5
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• pp.1536-1543
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• 2000

In this paper, we propose a multiple access scheme for efficient transmission of realtime and non-realtime data in IMT-2000 through cdma2000's CDMA MACD. On the contrast to the conventional circuit-based service, this framework is packet-oriented service. maximum number of simultaneous subscribers increases due to the statistical multiplexing based on variable transmission rate of realtime data. System performance is evaluated and compared with conventional circuit-based scheme considering transmission delay and channel utilization by computer simulation.

• ETRI Journal
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• v.26 no.1
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• pp.48-52
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• 2004

In this letter, we consider a new packet scheduling algorithm for an orthogonal frequency division multiplexing access/frequency division duplex (OFDMA/FDD)-based system, e.g., mobile broadband wireless access or high-speed portable internet systems, in which the radio resources of both time and frequency slots are dynamically shared by all users under a proper scheduling policy. Our design objective is to increase the number of non-realtime service (e.g., WWW) users that can be supported in the system, especially when the minimum bit rate requirement is imposed on them. The simulation results show that our proposed algorithm can provide a significant improvement in the average outage probability performance for the NRT service, i.e., significantly increasing the number of NRT users without much compromising of the cell throughput.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.141-149
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• 2012

This paper proposes a resource management and allocation algorithm to guarantee QoS continuity of realtime multimedia services and to maximize the resource utilization in heterogeneous wireless networks simultaneously. This scheme reserves the appropriate resources to be used by real-time multimedia services and allocates those resources left unused due to decreased transmission rate of realtime services to non-realtime services. Those resources can be preempted by the need of realtime services later. Performances are analyzed by simulation.

• The Journal of Korean Institute of Next Generation Computing
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• v.15 no.4
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• pp.51-61
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• 2019

In this paper, we have implemented soil simulation using fluid simulation technology. A widely used NVIDIA FleX was used to represent the soil generated by excavation work. FleX is a particle-based physics simulation library that combines SPH (Smoothed-particle hydrodynamics) and Position Based Dynamics techniques. However, since the soil has not only fluid properties but also non-fluid properties, it is difficult to simulate with the functions provided by conventional FleX. In this study, we added a technique to simulate non-fluid behavior using existing Flex. This can lead to effective results improvement at low cost.

• The Journal of the Korea Contents Association
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• v.3 no.2
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• pp.65-72
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• 2003

In this paper, the new scheme using a Combined Cache(CC) that combing the Paging and Routing Cache(PRC) and an alternative handoff method according to the type of data transmission for achieving the efficient realtime communication. The PRC and quasi-soft handoff method reduce the path duplication. But they increase the network traffic load because of the handoff state packet of Mobile Host(MH). Moreover the use the same handoff method without differentiating the type of transmission data. Those problems are solved by operating U with a semi-soft handoff method for realtime data transmission and with a hard handoff method for non-realtime data transmission. As a result or simulation a better performance is obtained because of the reduction of the number of control packet in case that the number of cells are below 20. And the packet arrival time and loss of packet decreased significantly for realtime data transmission.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.565-572
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• 2007

3G Long Term Evolution (3G LTE) is a next generation cellular networks system capable or providing various mobile multimedia services by using OFDMA and MIMO based radio access technology. Among many differences from existing WCDMA based systems, the facts that 3G LTE uses Physical Resource Block (PRB) as its radio resources and provides all services through the PS domain make the development of new resource management schemes necessary. This paper proposes an adaptive partitioning based downlink call admission control scheme. It separates realtime call requests from non-realtime ones, specifies maximum allowable resource amounts for each type, but if the maximum is exceeded, call requests are accepted with probability proportional to remaining resource amounts. Despite the fact that such adaptive concept has been already adopted by other call admission schemes, the contributions of our paper, which are that we are able to find an efficient way to apply the proposed scheme exploiting PRB characteristics and measure the resource usage of base stations by PRB utilization and payload ratio, are still valid. When judging from simulation results in comparison with others, our scheme is able to prioritize realtime call requests over non-realtime ones, and at the same time, overall system performance is superior.