• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.10a
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• pp.113-118
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• 2008

The present research addresses the system design for building a geospatially-based web services application for mobile users. In recent years, geospatial information(GI) and Geographic Information Systems(GIS) are significant resources in decision-making analyses at various levels of society and activities. Recently, the integration of GIS and web services, called GIS web services, provides the wider implementation of GIS. At the present time, accessing, presenting, and manipulating updatedgeospatial information to locate geo-related facility services are real challenges related to application developers to implement for foot-travelers properly. The present paper investigates how the web services work in a GIS for discovering geo-related facility services such as a restaurant and post office in the user's vicinity. Thus, a prototype, with an architecture consisting of a windows application on the client side as well as facility services and geo-engineon the server side, were designed and implemented with the proposed GIS web services platform. On both the client and server sides, visual studio .Net technology was used. A geo-engine on the server side was also built with ESRI's MapObjects. Following successful implementation of the prototype presented in this study, the mobile user is able to invoke remote web services to assess the location of various facilities such as restaurants. Moreover, the present research demonstratesthat web services are not restricted only to web-based use, but can also be utilized by any web-connected application.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2024-2029
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• 2005

In this paper, it is shown how a mobile robot can navigate with high speed in dynamic real environment. In order to achieve high speed and safe navigation, a robot collects environmental information. A robot empirically memorizes locations of high risk due to the abrupt appearance of dynamic obstacles. After collecting sufficient data, a robot navigates in high speed in safe regions. This fact implies that the robot accumulates location dependent environmental information and the robot exploits its experiences in order to improve its navigation performance. This paper proposes a computational scheme how a robot can distinguish regions of high risk. Then, we focus on velocity control in order to achieve high speed navigation. The proposed scheme is experimentally tested in real office building. The experimental results clearly show that the proposed scheme is useful for improving a performance of autonomous navigation. Although the scope of this paper is limited to the velocity control in order to deal with unexpected obstacles, this paper points out a new direction towards the intelligent behavior control of autonomous robots based on the robot's experience.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.71-79
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• 2003

Existing web-based system management software solutions show some limitations in time and space. Moreover, hey possess such as shortcomings unreliable error message announcements and difficulties with real-time assistance supports and emergency measures. In order to solve these deficiencies, Wireless Remote Control System(W-RCS) was designed and implemented. W-RCS is able to manage and monitor remote systems by using mobile communication devices for instantaneous control. The implementation of W-RCS leads to these security problems as well as solutions to aforementioned issues with existing web-based system management software solutions. Therefore, this paper has focused on the security matters related to W-RCS. The security functions based on public key infrastructure include mobile device user authentication and target system access control. The W-RCS allows real-time user authentication, increases the flexibility of resource administrators and mobile device non, and provides not only uninterrupted services, but also safe mobile office environments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.3
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• pp.473-479
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• 2008

Generally, HDDs are widely used as data storage device in office, home and mobile machineries. So, it is used for various applications or tasks, such as file copy, file download, music and movie play etc., in various environment. In spite of this kind of varieties in tasks and environment in which HDDs perform, most commercial HDDs hardly control its operations adaptively to these varieties. Thus, it is preferred to optimize the performance and energy consumption of HDDs according to the task and/or the environment. So, this paper proposes a new fuzzy inference algorithm which adaptively controls HDDs operations and may also easily be implemented as the firmware of HDDs and run in the restricted environment such as embedded systems.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2007.05a
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• pp.47-54
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• 2007

In this study, we consider the movement-based registration (MBR), location-based registration (LBR) and distance-based registration (DBR) schemes. Analytical models based on a 2-dimensional random walk in a hexagonal cell configuration are considered to analyze and compare the performances of these three schemes. We focus on the derivation of the registration costs of LBR and DBR using an analytical method and then show that DBR always outperforms both MBR and LBR. Numerical results are provided to demonstrate the validity of our models under various circumstances.

• Journal of the Korean Society of Safety
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• v.20 no.1 s.69
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• pp.137-142
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• 2005

This study aims to survey the fatal industrial accidents attributed to crane, and to present their preventive measures based on the results of the survey. The survey was on the basis of 60 fatal accidents caused by crane from January 1998 to July 2003. The results showed that 1) of varying types of crane, fatal accidents were most frequently caused by mobile no: 2) more crane accidents occurred on weekend of Friday and Saturday by a day of the week; 3) experienced crane operators with long length of work or the age of over 40 were more frequently subjected to fatal accidents compared to novice operators; and 4) crane accidents were more attributable to unsafe acts such as poor working method, non-observance for safe working rules, etc. than hardware aspects of crane itself. It is recommended that for reducing crane accidents, more practical education and training for crane operation be reinforced.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9B
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• pp.1579-1587
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• 2000

This paper presents the properties of the RF part in the receiving system based in IMT-2000 terminal technology. It mainly discuss the RF parameter performance of the receiving system for mobile telecommunication comparable to IS-98A and J-STD-018 specifications of commercially available CDMA and PCS, and is to anticipate the processing gain of the IMT-2000 receiving system, processing gain according to data processing rate, and terminal noise figure according to processing gain, relationship between noise figures according to Eb/Nt, Ioc. It is performed by such analysis method as CDMA and PCS receiving systems. Transmission bandwidth is n$\times$1.25 MHz(n=1, 3, 6, 9, 12) which is recommended by Qualcomm and NTT, the leading company in cdma 2000. Data transmission rate of IMT-2000 is classified into three cases as in moving vehicle environment of 144Kbps, outdoor pedestrian environment of 384Kbps, and indoor office environment of 2Mbps

• Journal of information and communication convergence engineering
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• v.8 no.4
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• pp.437-442
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• 2010

Ubiquitous mobile computing is becoming easier and more attractive in this ambient technological Internet world. However, some portable devices such as Personal Digital Assistant (PDAs) and smart phones are still encountering inherent constraints of limited storages and computing resources. To alleviate this problem, we develop a cost-effective protocol, iATA to transfer ATA commands and data over TCP/IP network between mobile appliances and stationary servers. It provides mobile users a virtual storage platform which is physically resided at remote home or office. As communications are made through insecure Internet connections, security risks of adopting this service become a concern. There are many reported cases in the history where attackers masquerade as legitimate users, illegally access to network-based applications or systems by breaking through the poor authentication gates. In this paper, we propose a mutual authentication and secure session termination scheme as the first and last defense steps to combat identity thief and fraud threat in particular for iATA services. Random validation factors, large prime numbers, current timestamps, one-way hash functions and one-time session key are deployed accordingly in the scheme. Moreover, we employ the concept of hard factorization problem (HFP) in the termination phase to against fraud termination requests. Theoretical security analysis discussed in later section indicates the scheme supports mutual authentication and is robust against several attacks such as verifiers' impersonation, replay attack, denial-of-services (DoS) attack and so on.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.83-88
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• 2006

Many applications in the area of location-based services and personal navigation require nowadays the location determination of a user not only in outdoor environment but also indoor. To locate a person or object in a building, systems that use either infrared, ultrasonic or radio signals, and visible light for optical tracking have been developed. The use of WiFi for location determination has the advantage that no transmitters or receivers have to be installed in the building like in the case of infrared and ultrasonic based location systems. WiFi positioning technology adopts IEEE802.11x standard, by observing the radio signals from access points installed inside a building. These access points can be found nowadays in our daily environment, e.g. in many office buildings, public spaces and in urban areas. The principle of operation of location determination using WiFi signals is based on the measurement of the signal strengths to the surrounding available access points at a mobile terminal (e.g. PDA, notebook PC). An estimate of the location of the terminal is then obtained on the basis of these measurements and a signal propagation model inside the building. The signal propagation model can be obtained using simulations or with prior calibration measurements at known locations in an offline phase. The most common location determination approach is based on signal propagation patterns, namely WiFi fingerprinting. In this paper the underlying technology is briefly reviewed followed by an investigation of two WiFi positioning systems. Testing of the system is performed in two localization test beds, one at the Vienna University of Technology and the second at the Hong Kong Polytechnic University. First test showed that the trajectory of a moving user could be obtained with a standard deviation of about ${\pm}$ 3 m.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4108-4122
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• 2016

To address challenges of an unprecedented growth in mobile data traffic, the ultra-dense network deployment is a cost efficient solution to off-load the traffic over other small cells. However, the real traffic is often much lower than the peak-hour traffic and certain small cells are superfluous, which will not only introduce extra energy consumption, but also impose extra interference onto the radio environment. In this paper, an elastic energy efficient cell management scheme is proposed based on flow scheduling among multi-layer ultra-dense cells by a SDN controller. A significant power saving was achieved by a cell-level energy manager. The scheme is elastic for energy saving, adaptive to the dynamic traffic distribution in the office or campus environment. In the end, the performance is evaluated and demonstrated. The results show substantial improvements over the conventional method in terms of the number of active BSs, the handover times, and the switches of BSs.