• Journal of KIISE:Databases
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• v.37 no.1
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• pp.22-32
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• 2010

Location-based services have been expanded rapidly in local and overseas markets due to technological advances and increasing applications of wireless internet. Various researches have been made to manage efficiently the location information of moving objects. A basic location-based alert service provides alerting messages automatically when either entering or leaving a specific location and it is expected to become one of the most important location-based services. Location-based alert services require a location polling method to acquire current locations for a large number of moving objects. However, a simple periodical location polling method causes severe system overload because a system should keep updating location information of the moving objects ceaselessly. Most location polling algorithms for location-based alerting services are not suitable for mobile users with dynamic and unsteady moving patterns. In this paper, we propose an improved location polling algorithm for location-based alerting services to reduce the amount of location information acquisition and therefore, to decrease the system load. Various experiments show that the proposed algorithm outperforms other algorithms.

• Journal of the Korean Institute of Gas
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• v.24 no.5
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• pp.10-19
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• 2020

Valve leak accidents in petrochemistry plants and gas utilities cause human and property damage. The main reason why happen gas inhalation, poisoning, fire and explosion accidents is gas valve leakage. To prevent gas leakage, inspectors check the facilities in the field. And they are at risk of gas leak accidents. So we applied IoT-based risk assessment, monitoring and automatic control system. It can detect both internal and external gas leakage, do real-time monitoring of industrial valve in the plant by using hybrid sensor. As the new safety management system for industrial valve is developed, it needs method to evaluate device performance and environmental components for the system. This study is about development of method to verify performance of the explosion-proofed hybrid sensing system include gas detector and optical fiber sensor supporting wire and wireless communication.

• The Journal of the Korea Contents Association
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• v.18 no.10
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• pp.415-424
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• 2018

The purpose of this study was to examine the physical environmental readiness for smart learning and the actual utilization of smart devices by special education teachers, and to suggest ways to vitalize smart education. For this, a 14-item survey questionnaire was developed, which touched upon issues regarding the availability of wireless internet service and teachers' utilization of smart devices. An online survey was conducted among a randomly chosen sample of 991 special education teachers across the nation, including teachers who work at special schools for developmentally disabled students and in special classes at all three levels of regular schools.The collected data was analyzed with the method of a cross-time-frequency analysis using a SPSS 21.0 statistics program. The research findings indicated that both special schools and classes had a poor smart education environment and that special education teachers were having a harding time because of the lack of the infrastructure and additional expenses. In addition, special education teachers were found to use smart device mostly for the purpose of motivating students. These research findings propose that it is urgent to set up a proper smart education environment for special needs students and to provide a systematic training program for special education teachers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.327-332
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• 2017

As Internet of Things (IoT) technology advances, there is a growing demand for location-based services (LBSs) to identify users' mobility and identity. The initial LBS system was mainly used to measure position information by measuring the phase of a signal transmitted from a global positioning system (GPS) satellite or by measuring distance to a satellite by tracking the code of a carrier signal. However, the use of GPS satellites is ineffective, because it is difficult to receive satellite signals indoors. Therefore, research on wireless communications systems like ultra-wide band (UWB), radio frequency identification (RFID), and ZigBee are being actively pursued for location recognition technology that can be utilized in an indoor environment. In this paper, we propose an LBS system that includes the 2.45GHz band for chirp spread spectrum (CSS), and the 3.1-10.6GHz band and the 250-750MHz bands for UWB using the IEEE 802.15.4a standard for low power-based location recognition. As a result, we confirmed that the 2.45GHz Industrial, Scientific and Medical (ISM) band RF transceiver and the ranging function can be realized in the hardware and has 0dBm output power.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.746-754
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• 2016

Smart healthcare systems, a convergent industry based on information and communications technologies (ICT), has emerged from personal health management to remote medical treatment as a distinguished industry. The smart healthcare environment provides technology to deliver vital information, such as pulse rate, body temperature, health status, and so on, from wearable devices to the hospital network where the physician is located. However, since it deals with the patient's personal medical information, there is a security issue for personal information management, and the system may be vulnerable to cyber-attacks in wireless networks. Therefore, this study focuses on a key-development and device-management system to generate keys in the smart environment to safely manage devices. The protocol is designed to provide safe communications with the generated key and to manage the devices, as well as the generated key. The security level is analyzed against attack methods that may occur in a healthcare environment, and it was compared with existing key methods and coding capabilities. In the performance evaluation, we analyze the security against attacks occurring in a smart healthcare environment, and the security and efficiency of the existing key encryption method, and we confirmed an improvement of about 15%, compared to the existing cipher systems.

• Journal of Service Research and Studies
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• v.3 no.2
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• pp.33-44
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• 2013

As the Internet and mobile services increase, the use of wired/wireless web contents services increase and the demand for various contents explosively grows. To survive in competitive market, and to minimize the errors and warnings for web accessibility and standardization, and then to maximize the web usability, the periodical evaluation for web site should be performed with the events of web marketing and campaign. Through the web evaluation, the errors for technical programming language and contents offering can be found and diagnosed. In this paper, the quantitative and qualitative evaluation method for web site providing web contents are presented, and the analytic results for the 138 home pages in domestic are evaluated to validate the quantitative methodology. The accessibility, standardization, and usability factor are adopted for the evaluation in which accessibility is evaluated for perceivable, operable, understandable, and robust discipline with K-WAH(Korea-Web Accessibility Helper) tool, the standardization are measured for the number of errors and warnings in technical language with the W3C validator, and finally the usability factor is analyzed for the number of visits, average visit duration, and bounce rate with Google Analytics. In addition to, the quantitative analysis is also performed with the consideration of cost for construction and operation of web site. From the results, in the case of total score of 100 in conversion with relative weight, the average and standard deviation are evaluated to be 55 and 14, respectively. The correlation analysis indicates that the coefficient is estimated as 0.058, and then correlation between the quantitative results and cost is evaluated to be a little positive.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.10a
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• pp.106-112
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• 2008

Personalization is user oriented dynamic method based on user preferences for easy access to what users want to view or get. It has become more important in mobile domain with rapid growth of wireless Internet and mobile phone market after success of web based market and therefore, it can be applied to service of spatial analysis result. In this paper, spatial analysis using user profile and notification service methods are proposed as one of personalized spatial data service methods for mobile users. A service system for spatial analysis with user profile is designed to prove possibility of spatial analysis based on user preferences and notification service is also designedto show generated output can be sent to user's mobile devices efficiently to make users informed of preferred information. Prototype system is implemented and it is applied to real estate data that has many selectable conditions by users. Information service based on user preferences can be applied to spatial data by using proposed system and it is efficient when cache module is used to shorten response time. Various user models for application domains and performance evaluation methods need to be developed in the future.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.9
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• pp.11-20
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• 2014

For Web-based applications in IoT environment, IETF CoRE WG has standardizing the CoAP. One of limitations of CoAP is that CoAP standard does not consider the mobility management of the CoAP sensor node. In this paper, we propose the mobility management protocol of CoAP sensor node by considering the characteristics of the constrained network. The proposed mobility management protocol supports for Web client to be transmitted the sensing data from CoAP node reliably while the CoAP sensor moves into different wireless networks. To do this, we designed the architecture with the separate IP address management of CoAP sensor node and presented the mobility management protocol, which includes the holding and binding mode, in order to provide the reliable transmission. Finally, the numerical analysis and simulation with NS2 tool have been done for the performance evaluation in terms of the handover latency and packet loss with comparing the proposed mobility management protocol with other the existing mobility management protocols. The performance result shows that the proposed mobility management can provide the transmission of sensing data without the packet loss comparing with the existing mobility management protocol reliably.

• The Journal of the Korea Contents Association
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• v.10 no.2
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• pp.81-88
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• 2010

This paper describes a development of next generation information remote retrieval and warning system that enables the user to make slope information retrieval remotely for a rockfall and landslide disaster reduction from mobile environments. And this system will be able to warn with a real-time stability condition about the slope which circumference are contiguous in standard user location. Slope information which provides to the user, become the service which upgrades from depth deep information directness will be able to confirm in order from field with applies multimedia style information which is various. In order to retrieve slope information with the wire and wireless internet from the remote place, we used mobile PC carrying is simple. Also this system attached GPS receiver to mobile PC in order to confirm user location as a real-time from the electronic map from field. Specially this system user location divide the safety of the slope which within the area where are fixed in the center are representative with 'safe area', 'collapse area' and 'collapse forecast area' etc. And to indicate with the icon of each other different color simultaneously in the electronic map. With like that reason, this system which sees the user even while moving safety condition about circumferential slope from the electronic map is having the strong point will be able to grasp with a real-time in one eye. Also warning message leads at the case real-time when the collapse will occur in specific slope, to inform to the user. Therefore this system which sees will be able to reduce the disaster which is caused by in landslide a very big strong point and has.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.7
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• pp.744-753
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• 2015

This paper presents the results of research on developing marine unified communications to provide VoIP service based on marine satellites. With the recent popularity of smart-phones and other mobile devices, the demand for Internet-based wired and wireless unified technology has been growing in marine environments, and increasing interest is being directed to VoIP products and service models with high price competitiveness and the ability to deliver a variety of services. In this regard, this research designed three instruments, developed their unit modules, and verified their performances. These three instruments included the following: (1) a marine VoIP module equipped with an analogue gateway that can be linked to the existing devices used in vessels, which is more than 80% smaller than that of a land system; (2) a text/voice/video engine for marine satellite communications that runs on technology that minimizes communication data usage, which is a core technology for a marine VoIP service; and (3) a unified communication service that can support multilateral cloud-based message conversations, telephone number-based call functions, and voice/video calling between a private space in a ship and shore.