• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.3 s.303
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• pp.31-40
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• 2005

In this paper, we develop an approach toward JSC(Joint Source-Channel Coding) method for MPEG-4 based FGS(Fine Granular Scalability) video coding and transmission in fixed and mobile receiving environment(Digital Audio Broadcasting, DAB). The source coder used MPEG-4 FGS video codec, the channel coder used RCPC(Rate Compatible Punctured Convolution) code and the modulation method used QPSK modulation. We have considered channel environment of AWGN and mobile receiving environment. This study determined optimum Trade-off point between source bit rate and channel coding rate in variable channel states. We compared FGS-JSC method and general single layer CBR(Constant Bit Rate) transmission. In this results, FGS-JSC was appeared better performance than CBR transmission.

• Journal of Broadcast Engineering
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• v.8 no.2
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• pp.163-171
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• 2003

In this paper, we develop an approach toward Joint Source-Channel Coding for MPEG-4(Moving picture Experts Group) based video coding In fixed and mobile reception environment. We have considered channel environment of AWGN and mobile reception. The source coder used MPEG-4 video. the channel coder used RCPC(Rate Compatible Punctured Convolution) and the modulation method used QPSK(Quadrature Phase Shift Keying) modulation. This study determined optimum Trade-off point between source bit rate and channel coding rate In variable channel states. We compared Joint Source/channel Coding method and general constant bit rate transmission. In this results, Joint Source/channel Coding was appeared better performance than constant bit rate transmission.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.1
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• pp.49-54
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• 2011

In this paper, we represent a mobile robot which can recognize chemical odor, measure concentration, and track its source indoors. The mobile robot has the function of smell that can sort several gases in experiment such as ammonia, ethanol, and their mixture with neural network algorithm and measure each gas concentration with fuzzy rules. In addition, it can not only navigate to the desired position with vision system by avoiding obstacles but also transmit odor information and warning messages earned from its own operations to other nodes by multi-hop communication in wireless sensor network. We suggest the way of odor sorting, concentration measurement, and source tracking for a mobile robot in wireless sensor network using a hybrid algorithm with vision system and gas sensors. The experimental studies prove that the efficiency of the proposed algorithm for odor recognition, concentration measurement, and source tracking.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.1609-1612
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• 2004

Ad hoc network is a kind of new wireless network paradigm for mobile hosts. Ad Hoc wireless networks consist of wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration. Mobile hosts rely on each other to keep the network connected. Each host is not only mobile hosts but also router. So how to design a routing protocol is the most important problem. Dynamic source routing is a kind of routing protocol. In this paper we suggest a new automatic route shortening method and an energy-aware routing mechanism based on DSR.

• Journal of the Semiconductor & Display Technology
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• v.21 no.1
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• pp.136-141
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• 2022

In this paper, we designed, implemented, and verified the SLAM system that can be used on mobile devices. Mobile SLAM is composed of a stand-alone type that directly performs SLAM operation on a mobile device, and a mapping server type that additionally configures a mapping server based on FastAPI to perform SLAM operation on the server and transmits data for map visualization to a mobile device. The mobile SLAM system proposed in this paper is to mix the two types in order to make SLAM operation and map generation more efficient. The stand-alone type SLAM system was configured as an Android app by porting the OpenVSLAM library to the Unity engine, and the map generation and performance were evaluated on desktop PCs and mobile devices. The mobile SLAM system in this paper is an open source project, so it is expected to help develop AR contents based on SLAM in a mobile environment.

• The Transactions of the Korea Information Processing Society
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• v.7 no.4
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• pp.1217-1226
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• 2000

Traditionally, Mobile Teletraffic model consists of two sub-models, i.e. the network traffic model and the traffic source model. In this paper, we present the traffic source model by developing MobCall (Mobile Call Simulator) which analyses various mobile wireless environments based on regional characteristics that the base stations are located. User mobility is presented by regional average vehicle speeds and the transportation share rate. Moreover, the user mobility on subway, which is increasing in urban area, is considered in MobCall. And also, user's movements on highway are considered in MobCall. The object-oriented simulation platform, C++SIM, is used to implement MobCall. Using MobCall, the accumulated number of calls in residential and commercial regions, the handoff rate with respect to traffic sources of Seoul, the handoff rate on highway, and the handoff rate according to the call duration are presented. MobCall enables the simulation of dynamic handoff buffering and functional entity control of one base station according to the changes in user's calling pattern at the design phase. Also, when a new town is under construction by a detailed plan, MobCall is used to design the mobile network with regional characteristics and user mobility considered.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1624-1641
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• 2015

Instantaneous relay (relay-without-delay) using interference alignment is a promising approach to neutralizing interference and improving system capacity. In Wang Chenwei's work, a 2-user scenario required both source and relay to access the global channel state information (CSI). This paper shows a new method of interference alignment improves the degrees of freedom (DoF) prominently for the 3-user MIMO interference channel with instantaneous relay. This new method is focused on the relay node that completes the alignment interference neutralization so the global CSI is obtained only once and the pressure on the base station can be mitigated. In addition, the 3-user MIMO interference channels with instantaneous relay can achieve 2M DoF when source and destination have M antennas, respectively. This method shows 33% improvement over the conventional method using interference alignment which obtains 3M/2 DoF.

• Journal of the Korean Geographical Society
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• v.46 no.6
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• pp.738-750
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• 2011

Partly due to the climate changes, flooding occurs more often than before. Particularly high urbanization causes more damages by flooding with unexpected downpours. Recent mobile telecommunication technology can help to reduce the damage by a natural disaster with quick alarming process. This research aimed to implement a flood warning GIS service system based on open source software and mobile hybrid application program with LBS. The developed system utilized location information of mobile clients for smart phone users to get alerted to flooding immediately. This service system would be very useful in urban areas to reduce the flood damages.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.4
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• pp.1373-1391
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• 2022

We investigate mobile multiple-input multiple-output (MIMO) molecular communication via diffusion (MCvD) system which is consisted of two source nodes, two destination nodes and one relay node in the mobile three-dimensional channel. First, the combinations of decode-and-forward (DF) relaying protocol and network coding (NC) scheme are implemented at relay node. The adaptive thresholds at relay node and destination nodes can be obtained by maximum a posteriori (MAP) probability detection method. Then the mathematical expressions of the average bit error probability (BEP) of this mobile MIMO MCvD system based on DF and NC scheme are derived. Furthermore, in order to minimize the average BEP, we establish the optimization problem with optimization variables which include the ratio of the number of emitted molecules at two source nodes and the initial position of relay node. We put forward an iterative scheme based on block coordinate descent algorithm which can be used to solve the optimization problem and get optimal values of the optimization variables simultaneously. Finally, the numerical results reveal that the proposed iterative method has good convergence behavior. The average BEP performance of this system can be improved by performing the joint optimizations.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1205-1211
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• 2003

Having information is most important at the present age. Internet is main source of obtaining information and mobile telecommunication let people communicate each other without any time and space limitation. Recently, advanced technology in telecommunication makes two-way service possible. So, the mobile internet service combined internet with mobile telecommunication is widely and rapidly promoted. Therefore user can transmit and receive a lot of information without time and space restriction using various application technologies. This paper deals with machinery that makes human do office work conveniently in vehicle using mobile internet service. Namely, it tries to design mobile internet machinery combining of wireless payment, GPS module, mobile internet, and mobile office etc. And that can transmit and receive e-mail or documents etc. This machinery has various objects, and design process has complexity. To reduce trial error and processing complexity, Axiomatic Design Method is used to design the machinery.