• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.1
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• pp.55-61
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• 2020

Social infrastructure facilities that have been under construction since the country's high-growth period are undergoing rapid aging, and, thus, safety assessments of large structures such as bridge tunnels, which can be directly linked to large-scale casualties in the event of an accident, are necessary. It is difficult to construct economical and efficient wireless smart sensor networks that improve structural health monitoring (SHM) because the existing wire sensors have a short signal reach. However, low-power wide-area networks (LPWANs) are becoming popular within the Internet of Things, and enable economical and efficient SHM. In this study, the technology trends of a wireless measuring sensor based on LoRa LPWANs were investigated, and an installation and maintenance plan for this type of sensor is proposed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.42-48
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• 2016

Extensive research effort has been made during the last decade to utilize wireless smart sensors for evaluating and monitoring structural integrity of civil engineering structures. The wireless smart sensor commonly has sensing and embedded computation capabilities as well as wireless communication that provide strong potential to overcome shortcomings of traditional wired sensor systems such as high equipment and installation cost. However, sensor malfunctioning particularly in case of long-term monitoring and unreliable wireless communication in harsh environment are the critical issues that should be properly tackled for a wider adoption of wireless smart sensors in practice. This study presents a wireless smart sensor network(WSSN) that can estimate unmeasured responses for the purpose of data recovery at unresponsive sensor nodes. A software program that runs on WSSN is developed to estimate the unmeasured responses from the measured using the Kalman filter. The performance of the developed network software is experimentally verified by estimating unmeasured acceleration responses using a simply-supported beam.

• Management & Information Systems Review
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• v.28 no.3
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• pp.191-210
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• 2009

Internet was first designed only for sending data, but as the time passed, internet started to evolve into a broadband multi-media web that is capable of transmitting sound, video, high-capacity data and more due to the demands of internet users and the rapid changing internet-communication technology. Domestically, in January, 2000 Saerom C&T, launched a free VoIP, but due to limited ways of conversation(PC to PC) and absence of a revenue model, and bad speech quality, it had hit it's growth limit. This research studied VoIP based on technological enhancement in super-speed internet. According to IDC, domestic internet market's size was 80,800 million in 2008, and it formed a percentage of 12.5% out of the whole sound-communication market. in case of VoIP, it is able to maximize it's profit by connecting cable and wireless network, also it has a chance of becoming firm-concentrated monopoly market by fusing with IPTV. Considering the fact that our country is insignificant in MVNO revitalization, regulating organizations will play a significant roll on regulating profit between large and small businesses. Further research should be done to give VoIP a secure footing to prosper and become popularized.

• The Journal of Korean Association of Computer Education
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• v.6 no.3
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• pp.197-205
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• 2003

For efficient teaching method a teacher should understand the current level of learners. Diagnostic evaluation is generally used to grasp a knowledge level of learners. However, it is not easy to take a diagnostic examination in every class because of time limitation. Accordingly, we propose a web based diagnostic evaluation system for efficient teaching method. In the proposed system, it is possible for teachers to feed diagnostic evaluation questions on the web at any time and for learners to take an online diagnostic examination without space and time limitation. In addition, the proposed system automatically grades the diagnostic evaluation and provides a teacher with various statistical data that can be a criterion to decide a proper teaching level.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.853-871
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• 2012

The location based service is divided into GPS that uses the artificial satellite or base transceiver station in order to cover the wide area and RTLS(Real Time Location System) using the Zigbee, RFID, CSS(Chirp Spread Spectrum), UWB, Bluetooth and Wi-Fi equipment in the space(close range) limited like the building inside or park. Moreover it also repeats the technical development upon through the acceleration of the development of the wire and wireless infrastructure and determination technology, the development of the Internet, diversification of the contents, and etc. As a result, it is expected to develop around the determination technology, witch is common core technology element, contents technology, Internet and mobile communication technology, and etc. afterward. In this research, the direction we investigate was to find and analyze new technology and standardization trend of LBS in order to contribute to the related industry.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.543-545
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• 2011

The concern which is abundant in MANET VoIP for comprising the mobility guarantee and mobile network is received without the infrastructure system between the mobile terminal node. However, because the access of system and border is easy, the issue which is big in the security problem becomes more than the wired network system with this convenience by the foreign network attacker differently. In this paper, we would like to the fundamental web network, NAT and concluding the security problem technology in which Firewall can inquire on MANET VoIP and whether it is appropriate or not which can solve this is proposed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3C
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• pp.293-298
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• 2008

Recently, with the development of mobile techniques and the consideration to conveniency of using, the research on Mobile RFID Reader technique is getting more and more attentions. Until now, all security authentication algorithms of RFID are algorithms about range between Tag and Reader. The range between Reader and backend DB is composed by wired networks, so it's supposed to be secure range. But it must be taken account of the problem of information security and privacy in wireless range during the design of Mobile RFID Reader. In this paper we design an blind signature scheme based on weil-paring finite group's ECC encryption scheme, and by using this blind signature we propose the anonymous authorization scheme to Mobile RFID Reader's users.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.6 s.336
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• pp.33-40
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• 2005

In this paper, we analyzed the DRMA(Dynamic Reservation Multiple Access) protocol with Rayleigh fading, shadowing, and capture effect for the Broadband fireless Access System. We consider the TDMA-based protocols, since these are based on the standard for IEEE 802.16 WMAN, IEEE 802.20 MBWA, and ETSI HIPERLAN//2. The results of analytical model will be apply the development of collision resolution algorithm, scheduling algorithm and the dynamic change of system parameters.

• Journal of the Korea Society of Computer and Information
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• v.15 no.11
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• pp.117-124
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• 2010

Appling centralized network management architecture SNMP(Simple Network Management Protocol) to wireless networks causes the network overhead, NAT(Network Address Translation) problem on AP, and performance degradation of mobile nodes. In this paper, we propose an integrated management scheme for wired and wireless networks using mobile agents in order to solve above problems. In our proposed scheme, SNMP is applied to manage wired networks and MAs of SNMP are implemented in APs or wireless nodes to manage wireless networks. In addition, we propose a method to reduce the redundant OID information within SNMP response messages. Through the analysis, we show that our proposal resolves the given problems and reduces the processing delay of the wireless nodes.

• Journal of Advanced Navigation Technology
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• v.12 no.6
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• pp.611-618
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• 2008

The development of information society together with information telecommunication's influence on the human society is a ripple effect and getting wider. Among those ripple effects the disaster prevention is in the public eye in the present day. On the way to the ubiquitous society the main techniques to be concerned in ubiquitous sensor networks are the field of damage of storm and flood, safety facilities, traffic safety, industrial safety, energy safety, fire fighting, specific safety of radioactivity escape incident, environmental pollution, sea pollution, mountain and forrest disaster so on. In this paper the USN technique based on the disaster prevention communication technology service and its requirement technology and application are studied.