• International Journal of Railway
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• v.3 no.2
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• pp.39-45
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• 2010

The RF-CBTC (Radio Frequency-Communication Based Train Control) System is a communication system in railroad systems. The communication method of RF-CBTC system is the wireless between the wayside device and on-board device. The wayside device collects its location and speed from each train and transmits the distance from the forwarding train to the speed-limit position to it. The on-board device controlling device controls the speed optimum for the train. In the case of the RF-CBTC system used in Korea, transmission frequency is 2.4 [GHz]. It is the range of ISM(Industrial Scientific and Medical equipment) band and transmission of voice and data is performed by CDMA (Code Division Multiple Access) method. So noises are made in the AWGN (Additive White Gaussian Noise) and fading environment. Currently, the SNR (Signal to Noise Ratio) is about 20 [dB], so due to bit errors made by noises, transmission of reliable information to the train is not easy. Also, in the case that two tracks are put to a single direction, it is needed that two trains transmit reliable voice and data to a wayside device. But, by noises, it is not easy that just a train transmits reliable information. In this paper, we estimated the BER (Bit Error Rate) related to the SNR of voice and data transmission in the environment such as AWGN and fading from the RF-CBTC system using the CDMA method. Also, we supposed the SNR which is required to meet the BER standard for voice and data transmission. By increasing the processing gain that is a ratio of chip transmission to voice and data transmission, we made possible voice and data transmission from maximally two trains to a wayside device, and demonstrated it by using Matlab program.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.3
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• pp.229-235
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• 2019

The implementation of an in-band full-duplex wireless communication system is demonstrated in this study. In the analog/RF domain, the self-interference(SI) signal is reduced using a separate antenna for the transmitter and receiver paths, and most of the SI signal is canceled in the digital domain. A software defined radio(SDR) is used to implement the in-band full-duplex wireless communication system. The USRP X310 device uses transmitting and receiving antennas. By adjusting the gain of the transmitting and receiving ends of the SDR device, the magnitude of the SI signal entering the receiving antenna, and the size of the received signal from the outside, are both set to -64 dB. To verify the in-band full-duplex wireless communication performance, the source data is image and orthogonal frequency-division multiplexing is used for modulation. A WiFi standard frame with a carrier frequency of 2.67 GHz and bandwidth of 20 MHz is used. In the received signal, the SI signal is canceled by digital signal processing and the SI signal is attenuated by up to 34 dB. OFDM demodulation was impossible when the SI signal was not removed. However, the bit error rate is reduced to $2.63{\times}10^{-5}$ when the SI signal is attenuated by 34 dB, and no error is detected in the 100 Mbit data output as a result of passing through the Viterbi decoder.

• Journal of the Korea Convergence Society
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• v.13 no.4
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• pp.53-61
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• 2022

Accidents are steadily occurring due to machine defects and carelessness during LNG storage operations. In previous studies, an environmental sensor module capable of measuring pressure, temperature, gas concentration, and flow to detect danger in advance was developed and the response speed according to the amount of leaked gas was measured. This paper proposes the development of a wired and wireless communication module that transmits data measured by the environmental sensor module to embedded devices connected to wired and wireless networks of SPI, UART, and LTE. First, a data communication module capable of interworking with an environmental sensor is designed. Design a protocol between devices in the Local Control Part and wired and wireless protocols in the Local Control Part and Remote Control Part. Ethernet, WiFi, and LTE communication modules were designed, and UART and SPI channels that can be linked with embedded controllers were designed. As a result, it was confirmed through a UI (User Interface) that each embedded device transmits data measured by the environmental sensor module while simultaneously communicating on a wired and wireless basis.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.237-241
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• 2003

The world's supply of water in all forms is enormous. However, only a tiny fraction of the planet's supply is available to us as fresh water, and that is distributed very unevenly. About 97％ of oater volume is found in the oceans and is too salty for drinking, growing crops, and most industrial uses except cooling. In addition water supply crises in already-water-short-regions will intensify because population and industrialization increase. Today, remote monitoring and control systems are becoming the cost-effective management tools for almost all water user groups, including irrigators, water districts, municipal water suppliers, and wildlife management groups. This paper represents a new approach in the water-gate control using radio communication. The proposed device is simple in structure and suitable for implementation of water-gate control through the transceiver by radio communication. It was confirmed that the developed device was very efficient to control level of water-gate and to prove the up and down motion of water-gate through the LCD displayer.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.1-9
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• 2010

This paper describes parallel event-driven remote IT convergence applications which are a combination of traditional industry and IT Technology including advanced communication. In IT convergence system, events can occur currently from many sensors of devices or users. And IT convergence system must have a parallel processing method. In this paper, the parallel processing method was implemented using a thread and we developed a connection method between a device and a mode of communication which is a wireless communication or a power line communication. In addition to that, we developed object modeling, device, user and event modeling, based on XML (eXtensible Markup Language) using object-oriented modeling method. To efficiently show results in real time, systems provide various graphic user interfaces such as a bar graph, a table, and a combination of the two.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2014-2020
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• 2016

In general, automatic access control management system using smart door-lock must be always exposed to security vulnerability during wireless communication based on Bluetooth. In particular, important information such as a secrete key can be exposed to the attacker when the authentication protocol has been operating in the wireless section. Therefore important information exchanged in the radio section needs to be properly encrypted. In order to analyze security vulnerability for automatic access control management system of public facilities such as subway vent, GNU Radio platform and HackRF device will be considered and experimented. Proposed experimental system to perform software based power analysis attack could be very effectively applied. As a result, important information such as packet type, CRC, length of data, and data value can be easily decoded from wireless packet obtained from HackRF device on GNU Radio platform. Constructed experimental system will be applied to avoid some security problems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1498-1507
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• 2017

According to recent report, global mobile data traffic is expected to increase by 11 times from 2016 to 2020. Moreover, this growth is expected to be driven mainly by mobile video traffic which is expected to account for about 70% of the total mobile data traffic. To cope with enormous mobile traffic, we need to understand video traffic's characteristic. Recently, the repetitive requests of some popular content such as popular YouTube videos cause a enormous network traffic overheads. If we constitute a network with the nodes capable of content caching based on the content popularity, we can reduce the network overheads by using the cached content for every request. Through device-to-device, multicast, and helpers, the video throughput can improve about 1.5~2 times and prefix caching reduces the playback delay by about 0.2~0.5 times than the conventional method. In this paper, we introduce some recent work on content popularity-based caching techniques in wireless networks.

• The KIPS Transactions:PartC
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• v.9C no.5
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• pp.687-698
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• 2002

Together with the activation of wireless Internet, the interest for various integrated methods of the existing wired and wireless e-commerces is on the rise. For the integrated wired and wireless e-commerce, firstly, the optimized security and authentication under the radio communication environment should be decided. And also the user-friendly usage is important. In this paper, we designed and implemented wired and wireless interworking Mobile Wallet on terminal that can be used through both wired and wireless methods by developing electronic wallet module for electronic payment using MIDP (Mobile Information Device Profile) based on J2ME (Java 2 Micro Edition). The characteristics of mobile wallet implemented in this paper provide the stability through encoding/decoding payment information and on-line usage on wired/wireless environments through downloading electronic wallet. In addition, we also present safe and convenient payment method for e-commerce based on wired/wireless Internet.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.3
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• pp.585-590
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• 2012

In this paper, a system using vibrating wire sensor and zigbee wireless network has been implemented to monitor and manage the structure. The implemented strain controller drives vibrating wire sensor and computes strain from measuring frequency of the output signal. Temperature sensor is included to compensate strain by temperature. Using two axis acceleration sensor of strain controller can measure the direction of strain or deformation. To measure strain more effectively, wired and wireless communication function is included in this device. As results of experiments, it is shown that the developed system can be effectively applied to measure strain of the structure.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.7
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• pp.782-787
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• 2014

Due to the complicated steel structure and safety concern, it is very difficult to deploy wireless networks in power plants. This paper presents a hybrid network, named as $P^2HYMN$ (Power Plant HYbrid Maintenance Network), encompassing PLC (Power Line Communication), TLC (Telephone Line Communication), and Wireless LAN. The design goal of $P^2HYMN$ is to integrate multimedia data such as design drawings of control equipment, process data, and video image data for maintenance operation in electric power plants. A Multiplex Line Communication (MLC) device was designed and implemented to integrate PLC, TLC, and Wireless LAN into $P^2HYMN$. Performance test of $P^2HYMN$ has been conducted on a testbed under various conditions. The throughput of TLC was shown as 39 Mbps. Because the bandwidth requirement per camera is 8.5 Mbps on average, TLC is expected to support more thant four video camera at the same time.