• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.5B
• /
• pp.456-477
• /
• 2006

Due to advances in wireless communication technology and increasing demand for various types of wireless access, cellular, WLAN, and portable internet(such as WiBro and IEEE 802.16) systems are likely to be integrated into a unified wireless access system. This expectation premises the availability of multi-mode handsets and cooperative interworking of heterogenous wireless access networks allied by roaming contracts. Under such environments, a user may lie in the situation where more than one wireless accesses are available at his/her location, and he/she will want to choose the 'best' access among them. In this paper, we define the 'best' access(es) as the access(es) that charges minimum cost while fulfilling the required QoS of wireless access, and address the problem of choosing the optimal set of accesses theoretically by introducing a graph representation of service environment. Two optimal selection algorithms are proposed, which individually consider cases where single or multiple wireless access can be supported by multi-mode handsets.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2755-2761
• /
• 2011

The purpose of this study was to analyze and improve the communication interferences in the wireless communication equipments of the CBTC applied to a model intelligence train control system. So far, train positions have been traced by the conventional fixed blocking system to control the operation of the trains, but the new CBTC system uses the on-ground location to transmit the train positions wirelessly to the ground control center continuously, so being more vulnerable to communication interferences. Although the researcher analyzed and improved such interferences in the communication equipments of the CBTC system, there remain more rooms for its improvement.

• The Journal of the Korea Contents Association
• /
• v.5 no.4
• /
• pp.20-27
• /
• 2005

In this paper, m(mobile)-commerce system based on LBS is implemented. WIPI(Wireless Internet Platform for Interoperability) that supports COD as a mobile VM(Virtual Machine) is used. These experimental results show that the system we proposed could be very efficient for CRM(Customer Relationship Management) and target management. And also, server load and connection time is improved by this system. From now on mobile commerce system based on LBS can be usable at various areas in ubiquitous environment.

• Proceedings of the KIPE Conference
• /
• 2016.07a
• /
• pp.349-350
• /
• 2016

In the magnetically coupled wireless power transmit (WPT), the study of the multi-dimensional transmission coil to solve the low power transmission efficiency from the location of transmit coil and receiving coil is being developed. This paper, an important step in this study, presents the magnetically coupled model of the WPT system consist of the two-dimensional transmit coil and verifies by the simulation and experiment. The induced model in this paper can be used to design the WPT circuit and controller for the maximum transmission efficiency.

• Proceedings of the Korea Inteligent Information System Society Conference
• /
• 2001.01a
• /
• pp.198-201
• /
• 2001

Recently the wireless-internet has been spreading extensively. People are spending a large part of their time gaining access to information using a mobile device. With the rapid growth of on-line Electronic Commerce, the use of mobile devices creates a new paradigm that provides users with location-independent real time service. Although this new paradigm does have some advantages, limited process speed, low bandwidth, the low battery capacity of mobile devices, and a high rate of wireless network errors causes many overhead expenses during service time with the server. In this paper, we suggest an autonomous service delivery system, which provides mobile agent capability to users that cannot maintain a connection. We have developed the system based on java mobile agent technology. Using this system, we can provide more effective service to users when the user is sending requirements for service through a mobile device that has limited resources. Furthermore we can manage the contact server dynamically when new services are added.

• Proceedings of the Korean Information Science Society Conference
• /
• 2008.06a
• /
• pp.261-262
• /
• 2008

Due to technological advances, the manufacturing of small and low cost of sensors becomes technically and economically feasible. In recent years, an increasing interest in using Wireless Sensor Network (WSN) in various applications, including large scale environment monitoring, battle field surveillance, security management and location tracking. In these applications, hundreds of sensor nodes are left to be unattended to report monitored data to users. Since sensor nodes are placed randomly and sometimes are deployed in underwater. It is impossible to replace batteries often when batteries run out. Therefore, reducing energy consumption is the most important design consideration for sensor networks.

• Journal of Advanced Navigation Technology
• /
• v.16 no.3
• /
• pp.449-454
• /
• 2012

According to the development of the ubiquitous computing technic today, the sensor base system is becoming a big issue in IT fields. This study is to develop a smart weather watching system which allows us to carry out temperature measuring without regard to location and altitude using the sensor devices. this system is composed of the wireless receiver module(PC base) and the wireless measuring module(ATmega2560 base).

• Proceedings of the KIEE Conference
• /
• 2005.07d
• /
• pp.3046-3048
• /
• 2005

저비용, 저전력 운영이 가능한 초광대역(UWB) 통신기술의 핵심 기술 분야 가운데 하나인 무선위치기반 시스템(Wireless Location Based System) 혹은 무선측위기술은 향후 전기-IT융합 유비쿼터스 메쉬네트워크에서 휴먼인터페이스접목, 지능형홈 뿐만아니라, 유비쿼터스 환경의 ad-hoc 센서 네트워크에서 중요한 역할을 맡게된다. 본 논문에서는 다양한 방식의 무선측위기술에 대해 소개하고자 하며, 순차송수신방식을 이용한 UWB 무선측위기반 시스템 및 운영방안을 새롭게 제안하고자 한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.283-283
• /
• 2010

Smart street light controller is a product with advance micro controller base for energy saving in conventional street lighting systems. Intelligent Street light controller are specially developed for automation and energy saving in conventional street light systems and lighting systems. It is so designed that it operates on sunrise & sun set timings according to longitude of particular location with facilitate to set month wise civil twilight timings to cope up with all seasons. Dimming (Power down) mode selection switch on/off at fixed times with relay or contactor. Night dimming, staggering and intelligent control reduces burn hours and increases the lifetime of lamps with about 30% and low annual operating cost type base are among the most inexpensive wireless technologies available. Low initial costs As PLC wireless, there is no need to establish cable connection.

• Journal of IKEEE
• /
• v.11 no.4
• /
• pp.297-306
• /
• 2007

A sensor network is composed of a large number of sensor nodes that are densely deployed in a field. Each sensor performs a sensing task for detection specific events. After detecting this event, location information of the sensor node is very important. Range-based scheme of the proposed approaches typically achieve high accuracy on either node-to-node distances or angles, but this scheme have a drawback because all sensor nodes have the special hardware. On the other hand, range-free scheme provides economic advantage because of no needed hardware even if that leads to coarse positioning accuracy. In this paper, we propose a range-free localization algorithm without range information in wireless sensor networks. This is a range-free approach and uses a small number of anchor nodes and known sensor nodes. This paper develops a localization mechanism using the geometry conjecture (perpendicular bisector of a chord). The conjecture states that a perpendicular bisector of a chord passes through the center of the circle.