• 스마트미디어저널
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• 제4권4호
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• pp.47-55
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• 2015

최근 ICT 분야의 컴퓨팅 패러다임의 변화와 다양한 서비스를 지원하기 위한 VoIP 기술이 재조명 받고 있다. 본 논문에서는 Secured mobile VoIP 기반의 음성 서비스를 지원하기 위한 경량 가상화 기술인 Docker를 이용하여 소프트웨어 PBX인 오픈소스 Asterisk와 하드웨어 플랫폼, 그리고 모바일 단말기간의 시스템들을 설계 및 구현하였다. 그리고 이를 기반으로 네트워크 트래픽의 지연 테스트와 음성 보안 테스트를 글로벌 실환경에서 실증 테스트를 통해 검증하였다.

• 대한원격탐사학회지
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• 제31권1호
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• pp.1-9
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• 2015

Mobility and cloud platform have become the dominant paradigm to develop web services dealing with huge and diverse digital contents for scientific solution or engineering application. These two trends are technically combined into mobile cloud computing environment taking beneficial points from each. The intention of this study is to design and implement a mobile cloud application for remotely sensed image fusion for the further practical geo-based mobile services. In this implementation, the system architecture consists of two parts: mobile web client and cloud application server. Mobile web client is for user interface regarding image fusion application processing and image visualization and for mobile web service of data listing and browsing. Cloud application server works on OpenStack, open source cloud platform. In this part, three server instances are generated as web server instance, tiling server instance, and fusion server instance. With metadata browsing of the processing data, image fusion by Bayesian approach is performed using functions within Orfeo Toolbox (OTB), open source remote sensing library. In addition, similarity of fused images with respect to input image set is estimated by histogram distance metrics. This result can be used as the reference criterion for user parameter choice on Bayesian image fusion. It is thought that the implementation strategy for mobile cloud application based on full open sources provides good points for a mobile service supporting specific remote sensing functions, besides image fusion schemes, by user demands to expand remote sensing application fields.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권10호
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• pp.4886-4907
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• 2019

The use of mobile devices is increasing in multimedia applications. The multimedia contents are delivered to mobile users over heterogeneous networks. Due to fluctuation in bandwidth and user mobility, the service providers are facing difficulties in providing Quality of Service (QoS) guaranteed delivery for multimedia applications. Multimedia applications depend on QoS parameters such as delay, bandwidth, and jitter to offer better user experience. The existing schemes use the single source and multisource delivery but are unable to balance between stream quality and network congestion for mobile users. We proposed a Quality Oriented Multimedia Content Delivery Scheme (QOMCDS) for the mobile cloud to deliver better quality multimedia contents for the mobile user. The multimedia contents are delivered to the mobile device based on the device's parameters and network environment. The objective video quality assessment models like Peak Signal-to-Noise Ratio (PSNR), Structural Similarity (SSIM), and Video Quality Measurement (VQM) are used to measure the quality of the video. The client side Quality of Experience metric such as Startup delay, Rebuffering events, and Bitrate switch count was used for evaluation. The proposed scheme is evaluated using dash.js and is compared to existing schemes. The results show significant improvement over existing multimedia content delivery schemes.

• Asian Journal of Atmospheric Environment
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• 제2권1호
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• pp.34-46
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• 2008

Emissions inputs for use in air quality modeling of Korea were generated with the emissions inventory data from the National Institute of Environmental Research (NIER), maintained under the Clean Air Policy Support System (CAPSS) database. Source Classification Codes (SCC) in the Korea emissions inventory were adapted to use with the U.S. EPA's Sparse Matrix Operator Kernel Emissions (SMOKE) by finding the best-matching SMOKE default SCCs for the chemical speciation and temporal allocation. A set of 19 surrogate spatial allocation factors for South Korea were developed utilizing the Multi-scale Integrated Modeling System (MIMS) Spatial Allocator and Korean GIS databases. The mobile and area source emissions data, after temporal allocation, show typical sinusoidal diurnal variations with high peaks during daytime, while point source emissions show weak diurnal variations. The model-ready emissions are speciated for the carbon bond version 4 (CB-4) chemical mechanism. Volatile organic carbon (VOC) emissions from painting related industries in area source category significantly contribute to TOL (Toluene) and XYL (Xylene) emissions. ETH (Ethylene) emissions are largely contributed from point industrial incineration facilities and various mobile sources. On the other hand, a large portion of OLE (Olefin) emissions are speciated from mobile sources in addition to those contributed by the polypropylene industry in point source. It was found that FORM (Formaldehyde) is mostly emitted from petroleum industry and heavy duty diesel vehicles. Chemical speciation of PM2.5 emissions shows that PEC (primary fine elemental carbon) and POA (primary fine organic aerosol) are the most abundant species from diesel and gasoline vehicles. To reduce uncertainties in processing the Korea emission inventory due to the mapping of Korean SCCs to those of U.S., it would be practical to develop and use domestic source profiles for the top 10 SCCs for area and point sources and top 5 SCCs for on-road mobile sources when VOC emissions from the sources are more than 90% of the total.

• 한국환경과학회지
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• 제11권7호
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• pp.697-703
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• 2002

In the present study, space allocation methods of pollutant emission from area and mobile sources are assessed by the actual application to air quality modeling of Pohang area. It is found that the TM-based modeling which allocates emission onto the 1km x 1km sized TM-grid system predicts almost the same mean ground-level concentration as that by the GIS-based modeling which uses geographical information of area and mobile sources directly, while maximum ground-level concentration by the TM-based modeling is predicted considerably lower than that by the GIS-based modeling. Moreover, the problem is found that the TM-based modeling causes deviation of mobile roads. In conclusion, it is anticipated to applying GIS-based modeling for a more accurate assessment of air quality in local scale.

• 한국멀티미디어학회논문지
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• 제13권7호
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• pp.1051-1061
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• 2010

국내 이동통신사들이 서로 다른 모바일 플랫폼을 채택하여 사용함으로 인해 개발자는 하나의 모바일 게임 콘텐츠를 서비스하기 위하여 각각의 플랫폼 특성에 맞추어 변환 작업을 하여야 한다. 하지만, 모바일 게임 콘텐츠를 타 플랫폼으로 이식하기 위한 변환 작업에 많은 시간과 비용이 소모되고 있다. 이는 다양한 콘텐츠가 제공되지 못하고 있는 원인이기도 하다. 본 논문에서는 이런 문제를 해결하기 위해 소스 레벨 콘텐츠 번역기를 이용하여 GNEX 플랫폼의 모바일 C 게임 콘텐츠를 스마트 플랫폼인 Android 플랫폼의 자바 콘텐츠로 자동으로 변환해주는 콘텐츠 자동 변환기 시스템을 구현하였다. GNEX C-to-Android Java 콘텐츠 자동 변환기 시스템은 단시간 내에 다른 플랫폼으로 콘텐츠를 이식할 수 있도록 하여 동일 콘텐츠를 다른 이동통신사에 서비스하는데 소모되는 시간과 비용을 최소화해준다. 또한, 기존 콘텐츠를 자동 변환하여 타 플랫폼에 서비스함으로써 콘텐츠의 재사용성을 높이고, 신규 콘텐츠의 생산성을 높여 사용자에게는 다양한 모바일 게임 콘텐츠를 제공할 수 있도록 지원한다.

• Journal of Communications and Networks
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• 제9권3호
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• pp.296-311
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• 2007

Mobile multi-robot teams are useful in many critical applications such as search and rescue. Explicit communication among robots in such mobile multi-robot teams is useful for the coordination of such teams as well as exchanging data. Since many applications for mobile robots involve scenarios in which communication infrastructure may be damaged or unavailable, mobile robot teams frequently need to communicate with each other via ad hoc networking. In such scenarios, low-overhead and energy-efficient routing protocols for delivering messages among robots are a key requirement. Two important primitives for communication are essential for enabling a wide variety of mobile robot applications. First, unicast communication (between two robots) needs to be provided to enable coordination and data exchange. Second, in many applications, group communication is required for flexible control, organization, and management of the mobile robots. Multicast provides a bandwidth-efficient communication method between a source and a group of robots. In this paper, we first propose and evaluate two unicast routing protocols tailored for use in ad hoc networks formed by mobile multi-robot teams: Mobile robot distance vector (MRDV) and mobile robot source routing (MRSR). Both protocols exploit the unique mobility characteristics of mobile robot networks to perform efficient routing. Our simulation study show that both MRDV and MRSR incur lower overhead while operating in mobile robot networks when compared to traditional mobile ad hoc network routing protocols such as DSR and AODV. We then propose and evaluate an efficient multicast protocol mobile robot mesh multicast (MRMM) for deployment in mobile robot networks. MRMM exploits the fact that mobile robots know what velocity they are instructed to move at and for what distance in building a long lifetime sparse mesh for group communication that is more efficient. Our results show that MRMM provides an efficient group communication mechanism that can potentially be used in many mobile robot application scenarios.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 B
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• pp.832-834
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• 1999

This paper is a study on the real-position measurements of mobile object using n network. 2-D PSD sensor is used to measure th position of moving object with light source. Position Sensitive Detector(PSD) is an useful which can be used to measure the position o incidence light in accuracy and in real-time. T the position of light source of moving target, neural network technique are proposed and applied. Real-time position measurements of the mobile robot with light source is examined to validate the proposed method. It is shown that the proposed technique provides accurate position estimation of the moving object.

• Journal of Communications and Networks
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• 제18권2호
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• pp.238-245
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• 2016

A sequence number checking technique is proposed to improve the performance of TCP connections in mobile ad hoc networks. While a TCP connection is initialized, a routing protocol takes the responsibility for checking the hop count between a source and destination pair. If the hop count is greater than a predefined value, the routing protocol decides to use a proxy node. The responsibility of a proxy node is to check the correctness of data packets and inform the missing packets by sending an acknowledgement from a proxy node to the source node. By doing so, the source node is able to retransmit any missing packet in advance without waiting until an end-to-end acknowledgement is received from the destination. Simulation results show that the proposed mechanism is able to increase throughput up to 55% in static network and decrease routing overhead up to 95%in mobile network.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.833-836
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• 2007

A low power and small area source driver using LTPS TFTs is proposed for mobile applications. This source driver adopts level shifter with holding latch function and new R-to-R type digital-to-analog converter (DAC). The power consumption and layout area of the proposed source driver are reduced by 23% and 25% for 16M colors and qVGA AM-OLED panel, respectively.