• Journal of information and communication convergence engineering
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• v.9 no.6
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• pp.676-682
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• 2011

Sybil attack can disrupt proper operations of wireless sensor network by forging its sensor node to multiple identities. To protect the sensor network from such an attack, a number of countermeasure methods based on RSSI (Received Signal Strength Indicator) and LQI (Link Quality Indicator) have been proposed. However, previous works on the Sybil attack detection do not consider the fact that Sybil nodes can change their RSSI and LQI strength for their malicious purposes. In this paper, we present a Sybil attack detection method based on a transmission power range. Our proposed method initially measures range of RSSI and LQI from sensor nodes, and then set the minimum, maximum and average RSSI and LQI strength value. After initialization, monitoring nodes request that each sensor node transmits data with different transmission power strengths. If the value measured by monitoring node is out of the range in transmission power strengths, the node is considered as a malicious node.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.124-131
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• 2015

In this paper, we proposed indoor positioning system using RSS(Received Signal Strength) positioning method and TSS(Transmission Signal Strength). The main point in the paper is to improve reliability of accuracy positioning with the area recognition algorithm and probabilistic algorithm, which can be effectively used indoor. In the test in 1-dimensional or 2-dimensional spaces, also we checked effective positioning system considered environment of propagation that is changed by reflection, refraction and multipath in according to space form. It is necessary to find place where urgent situation happen and quickly to respond the situation for patients or the weak. Therefore, we expect the positioning system proposed can apply to the field of traffic IT.

• Journal of Digital Contents Society
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• v.14 no.3
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• pp.349-356
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• 2013

Products of Wi-Fi devices in recent years offer higher throughput and have longer signal coverage which also bring unnecessary signal interference to neighboring wireless networks, and result in decrease of network throughput. Signal interference is an inevitable problem because of the broadcast nature of wireless transmissions. However it could be optimized by reducing signal coverage of wireless devices. On the other hand, smaller signal coverage also means lower transmission power and lower data throughput. Therefore, in this paper, we analyze the relationship among signal strength, coverage and interference of Wi-Fi networks, and as a tradeoff between transmission power and data throughput, we propose a range-aware Wi-Fi network scheme which controls transmission power according to positions and RSSI(Received Signal Strength Indication) of Wi-Fi devices and analyze the efficiency of the proposed scheme by simulation.

• Journal of Internet Computing and Services
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• v.18 no.6
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• pp.15-23
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• 2017

Wireless power transmission (WPT) for wireless charging is currently attracting much attention as a promising approach to miniaturize batteries and increase the maximum total range of an electric vehicle. The main advantage of the laser power beam (LPB) approach is its high power transmission efficiency (PTE) over long distance. In this paper, we present the design of a laser power beam based WPT system, which has a best WPT channel selection technique at the receiver end when multiple power transmitters and single power receiver are operated simultaneously. The transmitters send their transmission channel information via optically modulated laser pulses. The receiver uses the received signal strength indicator and digitized data to choose an optimum power transmission path. We modeled a vertical multi-junction photovoltaic cell array, and conducted an experiment and simulation to test the feasibility of this system. From the experimental result, the standard deviation between the mathematical model and the measured values of normalized energy distribution is 0.0052. The error between the mathematical model and measured values are acceptable, thus the validity of the model is verified.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4462-4466
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• 2013

In optical system, the signal and additive noise for statistical properties of a variety of ways to evaluate the performance of the system is essential for the optimization. In this paper, performance analysis of spectrum-sliced optical system in the optical pre-amplifier in the receiver the received signal by including the error limits for the bit that is, the bit error rate (BER: Bit Error Rate) required to maintain the average optical power represents the number of photons per bit is included in this paper to digital form, noticeable signal the receiver to calculate the sensitivity of the method for the calculation was performed. The general strength of the transmission of the modulated signal and digital signal transmission was required for the comparison of optical power. As shown in Figure 3, the general strength of the digital signal transmission system for transmitting a modulated signal compared with the case is improved by at least 10dB.

• Tunnel and Underground Space
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• v.33 no.5
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• pp.425-434
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• 2023

To measure the wear amount of the TBM disk cutter in real time, it is important not only to automate the measurement using sensors, but also to stably transmit the measured data to the information processing system. In this study, we investigated the viability of utilizing Bluetooth Low Energy (BLE) technology to wirelessly transmit sensor data from the TBM cutter head to a receiver located at the chamber's rear. Through laboratory experiments, we analyzed the Received Signal Strength Index (RSSI) of the receiver considering various signal strength of the transmitter, separation distances between the transmitter and receiver and chamber fill materials. Our results demonstrate that wireless data transmission is feasible across all tested conditions when the transmitter signal strength is 0 dBm or higher.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.53-56
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• 2003

In order to enhance the system capacity of multi rate IEEE 802.11 WLAN, we propose the transmission rate select method using the control frame in this paper. The transmission rate is selected dynamically based on the RSSI(Received Signal Strength Indicator) of received control frame. And we also propose the Enhanced NAV Update method for Fragmented MPDU burst transmission in multirate WLAN environment. This method can improve the system capacity by support the burst transmission of fragmented MPDU.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1914-1915
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• 2007

The period and strength of the pulse on the radial artery are important physiological factors, and they have been used to diagnosis in both Western and Eastern countries for a long time and has been developed as a unique method of diagnosis at each countries. Recently, there are a lot of systems which can give diagnosis information by recording the pulse wave and analyzing the characteristics of the pulse shape. This study describes the Pulse-Wave Measurement System which is able to measure the pulse wave signal using piezoresistive sensor and the pulse wave signal measured by the developed system is transmitted to a computer on the basis of the USB Driver. It has finally shown the the pulse wave signal measured by the sender is appeared to the host PC in real time. The Pulse-Wave Measurement System used the piezoresistive sensor to measure the pulse wave signal and the differential amplifier(AD620) to amplify the pulse wave signal which is small signal. And it used the ADC to convert analog to digital for the measured analog signal and the interface with a computer. It transmitted the measured pulse signal through USB transmission module to the host computer and Labview tool shows it. This Pulse-Wave measurement system will afford comvenience of detecting pulse wave to user related to oriental medicine.

• Journal of information and communication convergence engineering
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• v.13 no.1
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• pp.7-14
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• 2015

In a multi-hop wireless network, connectivity is determined by the link that is established by the receiving signal strength computed by subtracting the path loss from the transmission power. Two path loss models are commonly used in research, namely two-ray ground and shadow fading, which determine the receiving signal strength and affect the link quality. Link quality is one of the key factors that affect network performance. In general, network performance improves with better link quality in a wireless network. In this study, we measure the network connectivity and performance in a shadow fading path loss model, and our observation shows that both are severely degraded in this path loss model. To improve network performance, we propose power control schemes utilizing link quality to identify the set of nodes required to adjust the transmission power in order to improve the network throughput in both homogeneous and heterogeneous multi-hop wireless networks. Numerical studies to evaluate the proposed schemes are presented and compared.

• International Journal of Advanced Culture Technology
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• v.11 no.1
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• pp.395-402
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• 2023

The implementation of a hybrid network utilizing Power Line Communication (PLC) and Wi-Fi technologies has been demonstrated to improve signal strength and coverage in areas with poor connectivity due to internet shadow areas. In this study we strategically positioned Wi-Fi relays and utilized the capabilities of PLC technology to significantly improve signal strength and coverage in areas with poor connectivity. We also analyzed the effects of metallic obstacles on Wi-Fi signal propagation and proposed a solution to strengthen the signal enough to pass through them. Our experiment demonstrated the feasibility and potential of using this hybrid network in industrial scenarios for real-time data transmission. Overall, the results suggest that the use of PLC and Wi-Fi hybrid networks can be a cost-effective and efficient solution for overcoming internet connectivity challenges and has the potential to provide high-speed internet access to areas with unreliable signals.