• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.851-860
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• 2013

To overcome a scarcity of radio resources to mobile broadband service, the usage of TV white space gains much attraction around the world. This paper carries out an interference analysis either by performing realistic experiments or by executing statistical Monte-Carlo simulation to exploit interference probability. The results obtained from experiments are compared to those from simulations in order to clarify the coexistence of utilization of TV band devices (TVBD) in indoor circumstances. Along the execution of our experiment in the presence of DTV receiver, we apply to a variety of transmission parameters proposed in FCC for TVBD. According to experimental and simulation works, the allowable transmission powers of TVBD systems are exploited for the plausible which are coexist on the first as well as the second adjacent frequency bands. Throughout results, it can conclude that TVBD systems can be coexisted via achieving proper transmission powers depending on the locations of themselves without showing harmful interference to DTV reception.

• Journal of Intelligence and Information Systems
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• v.15 no.2
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• pp.75-95
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• 2009

The aim of this research is to design and analyze a social network service model using mobile RFID based business card. This paper suggests how the behavior of exchanging business cards will be changed in ubiquitous environment and designs a social networking service model using a ubiquitous business card, which embeds a RFID tag. We describe the scenarios and analyze a role, value and potential benefits of participants of the u-SNS service model. For the proof of the superiority and the feasibility of our model, we compare it with its related researches and products based on the calculation of the benefits and costs of the alternatives.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.2
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• pp.301-308
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• 2017

With the popularization of smart phones and the development of the Internet, many people use smart phones to conduct identity verification procedures. smart phones are easier and faster to authenticate than personal desktop computers. However, as Internet hacking technology and malicious code distribution technology rapidly evolve and attack types become more diverse, authentication methods suitable for mobile environment are required. As authentication methods, there are methods such as possessive-based authentication, knowledge-based authentication, biometric-based authentication, pattern-based authentication, and multi-element authentication. In this paper, we propose a user authentication mechanism that uses collected information as authentication factor using smart phone. Using the proposed authentication mechanism, it is possible to use the smart phone information and environment information of the user as a hidden authentication factor, so that the authentication process can be performed without being exposed to others. We implemented the user authentication system using the proposed authentication mechanism and evaluated the effectiveness based on applicability, convenience, and security.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.509-515
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• 2004

Pulmonary function tests are widely used to diagnose and determine patients' therapy in clinic. And it was also applied in the research of the physiology and dynamics for lung disease. Among the pulmonary function tests, spirometry is the most easy and economic test. Spirometers are medical instruments that measure the instantaneous rate of volume flow of respired Bas. The mechanical spirometer was mostly used in the past. Up to the present, the most popular method of spirometer is the differential pressure technique with which change in the volume of flow are transferred to change in pressure. This kind of instrument suffers from several limitations, pressure drop, difficulty in maintenance and short period of calibration. Therefore, this study has begun to implement ultrasound spirometer, which is free of pressure loss and has wide range, focusing on the flow measurement technique and diagnostic algorithm.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.123-124
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• 2012

Over the past decades, information and communication service providing safe and efficient navigation have been tried in maritime area. However, there were provided different ways such as different protocol or different policy. It made hard to serve efficiently. The introduction of MSI as a part of e-navigation development can be a kind of concepts to solve this problem. This paper tries to suggest a conceptual design of onboard application middleware to be able to communicate the shore-side maritime safety information system, take into account the reuse of open-source software.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1811-1817
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• 2014

In this paper, a PID controller with interpolated gains by use of neural networks is proposed for the formation control problem that following robots track a leading robot with constant distances and angles when there are changes in the mass of the following robot. The whole control system is composed of a kinematic controller and a dynamic controller considering the robot dynamics. The dynamic controller is the PID controller with varying gains, and the proper gains are obtained for some representative masses of the follower robot by the genetic algorithm. Neural networks is trained using the genetic algorithm with the gain data obtained in the previous step. The trained neural network determines optimal PID gains for a random mass of following robot. Simulation studies show that for arbitrary masses of the tracking robot, the PID controller with interpolated gains by the trained neural network has better tracking performance than that of the PID controller with fixed gains.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.63-68
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• 2008

The ubiquitous technology is capable of innovating various area to constructing intelligent and network to all objects. This technology can construct network infrastructure to facilities for applying legacy industry and need to develop intelligent service that analyze context-aware through network. This paper derive and propose the introduction range of ubiquitous technology, which should be testified and analyzed network, and studied the detection and analysis of information for managing gas facilities. We investigate the current status of gas facilities and automatic reading system, testing and analyzing wireless personal area network and mobile communication by scalability, self-configuration, connection in underground. Furthermore, we propose modelization method for intelligent service and derive the introduction range for applying ubiquitous technologies for managing gas facilities.

• Journal of Internet Computing and Services
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• v.5 no.2
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• pp.75-84
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• 2004

Geocasting, a variant of the conventional multicasting problem, is one of communication type in which the data packets are delivered to a group of all nodes within a specified geographical region (i.e., the geocasting region) and is called location-based multicasting(LBM)(l). An Ad-hoc network is a dynamically reconfigurable and temporary wireless network where all mobile devices using batteries as energy resources cooperatively maintain network connectivity without central administration or the assistance of base stations. Consequently, the technique to efficiently consume the limited amounts of energy resources is an important problem so that the system lifetime is maximized. In this paper, we propose a LBPA(Location-Based Power Aware) geocasting algorithm that selects energy-aware neighbor to route a packet towards the target region In Ad-hoc network environments. The method Is such that the energy consumption is balanced among the nodes in proportion to their energy reserves. Through the simulations, the proposed LBPA algorithm shows better results, that is, as good as 40% on the average over the conventional LBM algorithm in terms of the network lifetime.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.704-710
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• 2000

본 논문에서는 클라이언트/서버 형태로 긴급 이벤트 자동 호출 기능을 처리할 수 있는 원격제어 시스템을 설계하고 구현하였다. 웹 애플릿을 기반으로 구현된 클라이언트 시스템은 상황실에 위치하여 직접적으로 제어를 담당하는 서버에게 원격 제어 명령을 내린다. 제어 명령은 서버시스템으로 전달되며, 서버시스템에 존재하는 구동기가 실질적으로 컨베이어 시스템을 제어하는 기능을 가진다. 여기서 컨베이어 시스템은 승용차 조립라인을 시뮬레이션 한 것이다. 이러한 원격제어 시스템에 이동 통신의 문자서비스를 이용하여 긴급한 상황을 자동으로 원격지에 있는 관리자에게 알려주는 기능까지 확대시켰다. 관리자는 원격 시스템을 항상 감시할 필요가 없이 어느 장소에서나 상황보고를 받을 수 있게 된다.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.11
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• pp.419-426
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• 2014

The recent trend of performance increase in the smart mobile devices demands more power consumption and lower batter life time. Among three battery models of mathematical model, electrochemical model and electric model, the Thevenin's equivalent circuit with non-linear function model of SOC in the electrical model is widely used. However, the OCV results have only limited accuracy because of the characteristic shift caused by temperature and age and atypical impedance property that cannot expressed by electrical components. In this paper, the new battery model that improves the accuracy of the existing models is proposed. In the proposed simulator the mathematical model for SOC characteristic is improved and the adjustment for the temperature, the age of battery and atypical electrical characteristics. In the experimental results of predicting of the battery in the static and dynamic state, the proposed simulator shows improved MSE comparing to the results of the existing methods.