• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.8
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• pp.1074-1081
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• 2021

It has recently been noticed that the headway of unlicensed wireless technology is necessary as user's demands of wireless tech increase and the development of high-speed data service by using low-power short-range wireless network is needed. Hence, it is inevitable to study sharing and coexistence for broadband spectrum of diverse unlicensed application with wide bandwidth. In this paper, an interference examination between unlicensed WiFi (Wireless Fidelity) in the 6GHz and OB (Outside Broadcasting) system which is an incumbent service in the same frequency band was conducted and it suggests separation distance for the coexistence. Thus, MCL (Minimum Coupling Loss) and MC (Monte Carlo) methods were used to set up interference scenarios for the interference analysis and compute the separation distance between two systems according to the same frequency band and frequency separation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.149-157
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• 2014

This paper is based on the fabrication of wireless control system for the building shading device. RF Module was controlled by UHF wireless CC1020 chip which has low electrical power and low electrical voltage. Also 447.8625~447.9875 frequency, 4800Baud data rate and 12.5 kHz channel spacing was controlled by the use of SPDT switch and with Microcontroller program. Furthermore, the helical antenna was used. The starting production of 447.8625~447.9875 kHz wireless electrical power was used. As the result, it did not exceed 10dBm which is the standard of low power wireless system. Shading efficiency was measured at 25%, 50%, 75% direction with controlling the interior temperature and the intensity of illumination at the rate of 1 hour. As the result, the intensity of illumination was lowered to 82~87% at 25% direction with $0.6{\sim}1.4^{\circ}C$ lowered temperature. At 50% direction, the intensity of illumination was lowered to 60~68% with $2.3{\sim}4.1^{\circ}C$ lowered temperature. And at 75% direction, the intensity of illumination was lowered to 41~47% with $3.4{\sim}5.1^{\circ}C$ lowered temperature.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.141-146
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• 2008

Recently, it is studying to provide to users through internet in the SensorWeb of OGC(Open Geospatial Consortium) saving and maintaining data and image information gathered from sensor network. It is necessary to study about data convergence as binding audio and video for delivering the sensing data and image information to users with real-time system. In this article, it suggests how to convergence sensing data and moving picture collected from the sensor network using index. This program indicates both of them that collected sensing data and information identified of moving picture in the integration index and based on this program provides sensing data moving picture at the same time referencing integration index, if the user asks. To verify suggested method designing real-time multimedia service structure using sensor network and image installation and implementing Ubiquitous realtime multimedia system integrating moving picture and sensing data based on index. As a result of this program, it is confirmed providing real-time multimedia service to request information of application service using integration index collected image and sensing data from wireless sensor network and image installation suggested data convergence method.

• International journal of advanced smart convergence
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• v.12 no.1
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• pp.92-100
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• 2023

Wireless communication technology is becoming increasingly prevalent in smart factories, but the rise in the number of wireless devices can lead to interference in the ISM band and obstacles like metal blocks within the factory can weaken communication signals, creating radio shadow areas that impede information exchange. Consequently, accurately determining the radio communication coverage range is crucial. To address this issue, a Radio Environment Map (REM) can be used to provide information about the radio environment in a specific area. In this paper, a technique for estimating an indoor REM usinga mobile robot and machine learning methods is introduced. The mobile robot first collects and processes data, including the Received Signal Strength Indicator (RSSI) and location estimation. This data is then used to implement the REM through machine learning regression algorithms such as Extra Tree Regressor, Random Forest Regressor, and Decision Tree Regressor. Furthermore, the numerical and visual performance of REM for each model can be assessed in terms of R2 and Root Mean Square Error (RMSE).

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.4
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• pp.89-96
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• 2016

In this paper, we study mobile data collector (MDC) based data-gathering schemes in wireless sensor networks. In Such networks, MDCs are used to collect data from the environment and transfer them to the sink. The majority of existing data-gathering schemes suffer from high data-gathering latency because they use only a single MDC. Although some schemes use multiple MDCs, they focus on maximizing network lifetime rather than minimizing packet delay. In order to address the limitations of existing schemes, this paper focuses on minimizing packet delay for given number of MDCs and minimizing the number of MDCs for a given delay bound of packets. To achieve the minimum packet delay and minimum number of MDCs, two optimization problems are formulated, and traveling distance and traveling time of MDCs are estimated. The interior-point algorithm is used to obtain the optimal solution for each optimization problem. Numerical results and analysis are presented to validate the proposed method.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.05a
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• pp.1-4
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• 2005

Information communication environment integrates communication, broadcasting and internet, and Digital Convergence service emerges in result. Thus, the effective routers are needed so that they can transmit a huge number of data to core internet through appropriate base center. Therefore, the network guaranteeing QoS in transport layer supports interoperability with different wireless networks. So as to users receive necessary information anywhere seamlessly, the network architecture focuses on packet transmission and it is efficient for the control layer switches and controls packets between different networks. Since individual users take advantage of different services and data, the effective router architecture must be designed. Hence in this paper we design monitoring technique to solve security problem and to support premium service to ultimate users. Thereafter, we run opnet simulation and show the improvement of proposed router architecture.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.49-54
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• 2008

Recently, with the development of wireless communications and GIS, interest about mobile computing is rising. In this case, the GIS needs to be placed in a constricted environment than the environment of server computing. For this reason large amounts of spatial data must be compressed into the mobile device. The compression technique of the spatial data is difficult and must be processed in the correct order because the size of the data is unpredictable. Therefore, in this paper, the cell-based compression technique of the spatial data for mobile GIS is presented. This paper includes the process of transformation of spatial data from a certain server to a mobile device by cell-based compression technique. In this paper, the cell-based compression technique of the spatial data has been proven practically efficient.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.5
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• pp.66-74
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• 2002

OFDM(Orthogonal Frequency Division Multiplexing)is a one of the nst promising digital modulation techniques adapted for Digital audio broadcasting or Digital TV since it is very robust against multipath fading channels. From 1997, since the OFDM technique was considered as the physical layer standard for the high data rate wireless LAN systems in the 5㎓ band, related studies have been studied actively. The key element to implement high data rate wireless LAN system using OFDM technique are IFFT and FFT modules. In this paper, new IFFT and FFT module are designed and implemented using current cut circuit based on the matrix-rounding process for the low-power consumptive operation and high-speed data processing. In addition to, we certify the available operation of the rounded IFFT/FFT module in the AWGN channel by using the BER performance simulation of IEEE 802.11TGa based OFDM modem with rounded IFFT/FFT module.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.39 no.5
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• pp.45-55
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• 2002

In this paper, we describe an outdoor augmented reality system using GPS tracking for position and attitude information. The system consist of a remote mobile operation unit and a ground operation unit. The remote mobile operation unit includes a real-time image acquiring device, a GPS tracking device, and a wireless data transceiver; the ground operation unit includes a wireless transceiver, a virtual image generating device, and an image superimposing device. The GPS tracking device for measurement of position and attitude of the remote mobile operation unit was designed by TANS Vector and RT-20 for DGPS. The wireless data transceiver was for data transmission between the remote mobile operation unit and the ground operation unit. After the remote mobile operation unit was installed on a vehicle and a helicopter, the system was evaluated to verify its validity in actual applications. It was found that the implemented system could be used for obtaining real-time remote information such as construction simulation, tour guide, broadcasting, disaster observation, or military purpose.

• Journal of Advanced Navigation Technology
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• v.13 no.1
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• pp.54-61
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• 2009

In this paper, Switching to digital TV broadcasting and mobile operators license expiration period of the frequency, time and 700MHz, 800MHz and 900MHz frequency band plan for the redistribution is actively being discussed. Redistribution policy direction of these frequency 800MHz (bandwidth 10MHz) integrated command frequency for wireless networks(i.e TETRA) is expected to be considered a redistribution. These Integrated Wireless Network Infrastructure configurations at the time and data communication capabilities of the system unwilling TETRA Release 2 standard for the system is presented. This system is analyzed that Release 1 of the existing system takes up more than 6 times the increase of frequency bands. Therefore, integration of the frequency band assigned to the command of a wireless network with the introduction of advanced systems will not be able to do. In this paper to the digital TV transition, and the policy based on analysis of trends in the 700MHz band for the integration of wireless networks, provides policy direction for the allocation plan.