• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1213-1237
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• 2019

Vehicular Ad-hoc Network (VANET) facilities envision future Intelligent Transporting Systems (ITSs) by providing inter-vehicle communication for metrics such as road surveillance, traffic information, and road condition. In recent years, vehicle manufacturers, researchers and academicians have devoted significant attention to vehicular communication technology because of its highly dynamic connectivity and self-organized, decentralized networking characteristics. However, due to VANET's high mobility, dynamic network topology and low communication coverage, dissemination of large data packets (e.g. multimedia content) is challenging. Clustering enhances network performance by maintaining communication link stability, sharing network resources and efficiently using bandwidth among nodes. This paper proposes a mobility-based, multi-hop clustering algorithm, (MBCA) for multimedia content broadcasting over an IEEE 802.11p-LTE-enabled hybrid VANET architecture. The OMNeT++ network simulator and a SUMO traffic generator are used to simulate a network scenario. The simulation results indicate that the proposed clustering algorithm over a hybrid VANET architecture improves the overall network stability and performance, resulting in an overall 20% increased cluster head duration, 20% increased cluster member duration, lower cluster overhead, 15% improved data packet delivery ratio and lower network delay from the referenced schemes [46], [47] and [50] during multimedia content dissemination over VANET.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권1호
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• pp.114-130
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• 2021

With the drastic growth of Information and Communication Technology (ICT) industry, global energy consumption is exponentially increased by mobile communications. The huge energy consumption and increased environmental awareness have triggered great interests on the research of dynamic distribution of cell user and traffic, and then designing the energy efficient cellular network. In this paper, we explore the temporal and spatial characteristics of human mobility and traffic distribution using real data set. The analysis results of cell traffic illustrate the tidal effect in temporal and spatial dimensions and obvious periodic characteristics which can be used to design Base Station (BS) dynamic with sleeping or shut-down strategy. At the same time, we designed a new Cell Zooming and BS cooperation mode. Through simulation experiments, we found that running in this mode can save about 35% of energy consumption and guarantee the required quality of service.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.119-122
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• 1998

Wireless ATM(WATM) intends to provide a broad range of mobile multimedia services through wireless access by mobility extensions from the fixed ATM-based network. Recently, there have been active researches about new handover techniques to support terminal mobility in WATM. In this paper we classify path reestablishment schemes into full reestablishment, path rerouting with a static COS, path rerouting with a dynamic COS, and path extension. For a backward lossy handover procedure, we analyze and compare the performances of path reestablishment schemes in terms of delay, service disruption time and cell loss.

• 한국자동차공학회논문집
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• 제9권1호
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• pp.205-215
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• 2001

In this study, modeling and analysis procedure for the dynamic analysis of a high mobility tracked vehicle system were studied. The vehicle model used in this investigation is assumed to be consist of two kinematically decoupled subsystems. The chassis subsystem consists of chassis frame, sprocket, support rollers, road wheels, idler wheel, road wheel arms and idle wheel arm, while the track subsystem is represented as a closed kinematic chain consisting of track links and end connectors interconnected by revolute joints with bushing. Nonlinear contact force module describing the interaction between track link, and sprocket, idler wheel, road wheel, support roller, ground was used. The effects of road wheel arms and idler wheel arm due to tension adjuster are also considered.

• 동력기계공학회지
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• 제14권3호
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• pp.39-45
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• 2010

The dynamic stability of a robot vehicle can be enhanced by the Force-Angle Stability Margin concept that considers a variety of dynamic effects. To evaluate the robot vehicle stability, a SPI(stability performance index), which is a function of the suspension arm angles, was used. If the SPI has a minimum value, the robot vehicle has maximum stability. The FASM and SPI concepts were incorporated in the mobility simulation by using ADAMS and MATLAB/Simulink. The simulation results using these concepts showed significant improvements of the vehicle stability on rough terrains.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2002년도 가을 학술발표논문집 Vol.29 No.2 (3)
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• pp.661-663
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• 2002

This paper introduces a dynamic location management with hierarchical location area, which helps in reducing location update(LU) and paging cost and hence total location management cost. Users are assigned to appropriate location area level utilizing the call-to-mobility ratio(CMR) value. CMR values are calculated each time a user enters a new cell by computing its mobility rate and incoming call rate, which are the two key factors for defining the size of the location area.

• 한국통신학회논문지
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• 제38B권11호
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• pp.879-894
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• 2013

최근 급격한 모바일 인터넷 트래픽의 증가로 인하여 3GPP LTE/SAE 네트워크에서 코어 네트워크내의 과다한 데이터 트래픽 수용문제와 시스템 확장성 문제가 중요 이슈로 부각되고 있다. 현재 P-GW (PDN Gateway)를 이동성 앵커(Mobility Anchors)로써 활용하고 있는 중앙 집중형(Centralized) 방식의 LTE/SAE 네트워크에서는 급격히 증가하고 있는 모바일 인터넷 트래픽 수요를 감당하기 어려울 것으로 전망된다. 본 논문에서는 이러한 문제를 해결하기 위하여 분산 P-GW를 지원하는 새로운 LTE/SAE 네트워크 구조를 제안하고 이에 적합한 동적 분산 이동성 관리 방안을 제안한다. 이를 위하여, P-GW의 분산 배치뿐만 아니라 제어 평면을 담당하는 MME (Mobility Management Entity)들이 각 단말(User Equipment, UE)의 PDN 연결당 형성되는 위치 정보를 동적으로 분산 관리하고, 그러한 분산 MME 및 분산 P-GW에 의하여 PDN 연결의 핸드오버를 처리하는 프로시저를 제안한다. 또한, 제안하는 분산 방식의 LTE/SAE 네트워크 구조와 기존 중앙 집중형 방식의 LTE/SAE 네트워크 구조에 대하여 핸드오버 지연시간과 데이터 처리율 측면에서 성능을 비교 분석한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.911-916
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• 2001

Structural acoustic modification method based on the structural mobility analysis is applied to reduce the structure-borne noise radiated from hard disk drive system. Sound intensity techniques and ODS(Operational Deflection Shape) techniques are also used in order to provide the structural acoustic information for the mobility modification. The sound intensity is for the acoustic visualization of the noise source locations, and the ODS is for the visualization of the vibration pattern and its dynamic characteristics of the noise sources. Using visualization information of sound and vibration, local structural input mobility is reduced in the frequency band of interest by designing asymmetrical wave-stringer structure in the wave-number domain as well as frequency domain. The overall sound pressure level is reduced by 4dB and its controlled sound power radiated from the disk drive is proved to under 2.8Bel in idle-spinning mode and 3.1 Bel in random-seeking mode, which are the lowest noise levels in the hard disk drive industry.

• 한국정보처리학회논문지
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• 제7권11S호
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• pp.3714-3722
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• 2000

인터넷에서 단말기의 이동성을 보장하기 위한 연구는 크게 매크로 이동성과 마이크로 이동성의 두 가지로 분류 가능하다. 매크로 이동성의 경우 IETF의 RFC 2002로 수렴되는 추세이나 마이크로 이동성의 경우 다양한 방안들의 논의 중이다. 본 논문에서는 기존의 Mobile IP에 LA(Local Agent) 개념을 도입하여 이동 노드의 빈번한 지역 핸드오프를 LA에 전담시켜 HA가 관여하지 않도록 하는 기법을 제안하였다. 따라서 최대 핸드오프 지연을 MN과 MN의 HA간 거리의 영향을 받지않고 일전 수준으로 제한할 수 있다. 등록비용과 핸드오프 지연으로 인한 패킷 손실 확률 측면에서 기존 Mobile IP와 LA 개념을 적용했을 경우에 대한 분석을 수행함으로써 제안된 모델이 Mobile IP의 성능향상을 시킬 수 있음을 검증하였다.

• 한국수소및신에너지학회논문집
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• 제34권5호
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• pp.478-489
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• 2023

In this study, fault diagnosis and detection methods developed to ensure the reliability of polymer electrolyte membrane (PEM) hydrogen electrolysis systems have been proposed. The proposed method consists of model development and data generation of the PEM hydrogen electrolysis system, and data-driven fault diagnosis learning model development. The developed fault diagnosis learning model describes how to detect and classify faults in the sensors and components of the system.