• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6A
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• pp.386-396
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• 2003

Recently, mobile communication systems have supported various services including internet from voice centric service as they evolve toward 3G. To accommodate the increasing number of users, an AAL2 multiplexing scheme is introduced in the UTRAN tub interface for link efficiency. However, limited radio resources and different requirements of various services make it difficult to guarantee the QoS requirements at radio access networks. The conventional AAL2/ATM multiplexing systems focused on the multiplexing efficiency of voice anddata services and QoS issues of real time and non real time services. In this paper, we classfy various services according to QoS requirements and propose AAL2/ATM multiplexing schemes using statistical multiplexing and scheduling with a rather simple structure to guarantee the given requirements. Simulation results show that the proposed schemes perform better than the conventional schemes to guarantee QoS requirements of various services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.11
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• pp.1139-1145
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• 2014

In shipyard site, a ship is constructed by integrating lots of modules that are made in several sites with different capabilities and specifications. Recently, it needs to make a shipyard to be smart communicating various multimedia information with wired and wireless broadband networks between hierarchical shipyards. In this paper, we propose an additional function of an LTE femtocell local gateway at a remote shipyard, an information exchange method between hierarchical shipyards, and an offload method to separate the general traffic. To reduce traffic of duplicated requests in shipyard, we apply a D2D communication scheme for supporting communication between shipyard equipments without IP service network. Hence, it is expected to increase the productivity of shipyard industry with mobile communications, D2D and broadband Internet technologies.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.9
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• pp.1359-1364
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• 2013

After platform changed from PC-based internet to mobile, SNS became new interactive media which relaces face-to-face interaction. the SNS users have already begun to recognize SNS as daily necessity. SNS market has been subdivided. In other words, SNS has entered into a period of vertical SNS that focus on contents and specific target. Therefore, It is necessary to analyze users for SNS planners. For this reason, analyzing why office workers who have the most powerful purchasing power use SNS is meaningful for SNS planners. Therefore, in this study, we analyzed the reasons for using SNS of office workers by studying relationship among office workers' stress, social support, self-expression and the use of SNS. As a result, the use of SNS has a significantly positive correlation with social support and self-expression. The self-expression in the SNS is not associated with stress, but rather it is the characteristics of the office workers. However the social support in the SNS affects to stress.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1486-1491
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• 2017

In this paper, we propose a private multimedia caching scheme based on wireless local area network (WLAN) to improve the quality of service for high capacity and high quality multimedia streaming services which are recently increasing and to reduce the traffic load of core networks. The proposed caching scheme stores multimedia in the storage device mounted on WLAN APs and provides streaming services on its own without Internet connection in accordance with the request from clients. We have implemented a test network based on real commercial networks and measured the performance of the proposed caching scheme in terms of frames per second (FPS) and buffering time. According to the performance measurement results, the proposed caching scheme can reduce the average buffering time by 73.3% compared to the conventional streaming scheme. In addition, the proposed caching scheme can also improve the average FPS by 71.3% compared to the conventional streaming scheme.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.13-20
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• 2016

The computerized management system for bridges is required due to the increased service life and number of bridges. This paper provides information and communication technology (ICT) - based bridge management system (BMS) to enable life cycle management through a comparative study with the development trend and function of domestic and foreign BMSs. BMS developed as an operation system combined an internet and mobile program, and was based on GIS technology and an object-based information management system. BMS supports the establishment of long-term strategies and short-term plans based on predicting the life-cycle performance profile and the necessary budget by object-based informatization for the whole life-cycle information of bridges. Useful knowledge information for supporting decision making was derived from the life-cycle management strategies establishment for approximately 6,000 existing bridges. BMS was developed to be applicable to all nationwide road bridges. In addition, it can be used practically to maintain the performance based on accurate maintenance result management, reducing cost by reasonable budget management, and enhancing the convenience and reliability of field data collection.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.11
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• pp.47-54
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• 2015

The number of users of SNS such as Twitter and Facebook increases due to the development of internet and the spread of supply of mobile devices such as smart phone. Moreover, there are also an increasing number of content pollution problems that pollute SNS by posting a product advertisement, defamatory comment and adult contents, and so on. This paper proposes an improved method of extracting the feature of content polluter for detecting a content polluter in SNS. In particular, this paper presents a method of extracting the feature of content polluter on the basis of incremental approach that considers only increment in data, not batch processing system of entire data in order to efficiently extract the feature value of new user data at the stage of predicting and classifying a content polluter. And it comparatively assesses whether the proposed method maintains classification accuracy and improves time efficiency in comparison with batch processing method through experiment.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.333-338
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• 2019

Satellite communication is not used by many people like mobile communication, but it is a necessary technology for public service and communication services, such as providing the Internet in military, disaster, remote education and medical services, island areas, and infrastructure vulnerable areas. However, most communication modems have problems with two-way communication with server as IP addresses are assigned to floating IP that change every time they communicate with the network. In this paper, we used the Raspberry Pi as the controller of the terminal device to communicate the network through the satellite modem and the PPP protocol, and to solve the problem of the modem with the floating IP, we used the text message function of the satellite modem. Through this process, two-way data links using the Thuraya geostationary orbit satellite were implemented.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.4
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• pp.180-186
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• 2022

Agrophotovoltaic (APV) system is an integrated system producing crops as well as solar energy. Because crop production underneath Photovoltaic (PV) modules requires delicate management of crops, smart farming equipment such as real-time remote monitoring sensors (e.g., soil moisture sensors) and micro-climate monitoring sensors (e.g., thermometers and irradiance sensors) is installed in the APV system. This study aims at introducing a decision support system (DSS) for smart farming in an APV system. The proposed DSS is devised to provide a mobile application service, satellite image processing, real-time data monitoring, and performance estimation. Particularly, the real-time monitoring data is used as an input of the DSS system for performance estimation of an APV system in terms of production yields of crops and monetary benefit so that a data-driven function is implemented in the proposed system. The proposed DSS is validated with field data collected from an actual APV system at the Jeollanamdo Agricultural Research and Extension Services in South Korea. As a result, farmers and engineers enable to efficiently produce solar energy without causing harmful impact on regular crop production underneath PV modules. In addition, the proposed system will contribute to enhancement of the smart farming technology in the field of agriculture.

• Journal of the Korea Society of Computer and Information
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• v.14 no.9
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• pp.37-46
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• 2009

The movement of the MR loaded on the train is confined to the bidirectional movement along the rail. Therefore, the AR connected to the MR can use the address information of the neighboring ARs and configure CoA in advance before performing L2 and L3 handoff. The MR can acquire new CoA immediately from the present AR after the movement detection procedure. The performance analysis shows that the proposed scheme can provide CoA to the MR about 1.8(s) at minimum and 4.98(s) at maximum faster than the Stateless scheme because the proposed scheme does not carry out any additional CoA and DAD procedure unlike the Stateless scheme.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.585-587
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• 2022

The visual motivation between AP devices is NTP-based visual motivation through the access of the Internet through the internal wired LAN, but this has several seconds of visual difference in hundreds of milliseconds (msec) depending on the network. The frame for the output of the video will vary depending on the application, but usually 24 (image) frames are output to the screen in one second. Therefore, the visual synchronization between peripheral devices can be performed through the adjacent moving camera device, not the wired method. The programming method of generating API for synchronization command when creating an application for visual synchronization and delivering it to AP through MAC may differ from the time in synchronization command according to the environment of the operating system at the transmission side and the situation of the buffer queue of the MAC. Therefore, as a method to solve this problem, the renewal of visual information in the device driver terminal controlling MAC can be much more effective.