• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.447-450
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• 2005

This paper describes an implementation of system based on ZIGBEE wireless communication technique to prevent for diseases of skin ailments and respiratory ailments as sensing the air pollutions that breaks out in the inside and purifying. ZIGBEE wireless communication technique has features - low battery consumption, low cost, acceptance of the maximum 256 node and simple protocol structure of below 32Kbyte. Hardware platform is implemented by using ATmega128L in ATmel corporation and 2.4GHz RF-IC CC2420 in Chipcon corporation and dust sensor(GP2Y1010AU) and gas sensor(GSBT11) that confirm degree of inside air pollution for ZIGBEE wireless communication technique.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.5
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• pp.416-422
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• 2012

This paper proposes a low power-loss current measurement using a resistor and bypass switch. Conventional current sensing method using a resistor has a disadvantage of power loss which degrades the efficiency of the entire systems. On the other hand, proposed measurement technique operating with bypass-switch connected in parallel with sensing resistor can reduce power loss significantly the current sensor. The propose measurement works for discrete-time sampling of current sensing. Even while the analog-digital conversion does not occur at the controller, the sensing voltage across the sensor still causes ohmic conduction loss without information delivery. Hence, the bypass switch bypasses the sensing current with a small amount of power loss. In this paper, a 90[W] prototype hardware has been implemented for photovoltaic MPPT experimental verification of the proposed low power-loss current measurement technique. From the results, it can be seen that PV power observation is successfully done with the proposed method.

• International Journal of Computer Science & Network Security
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• v.23 no.8
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• pp.121-136
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• 2023

Wireless Sensor Networks (WSNs) have many potential applications and unique challenges. Some problems of WSNs are: severe resources' constraints, low reliability and fault tolerant, low throughput, low scalability, low Quality of Service (QoS) and insecure operational environments. One significant solution against mentioned problems is hierarchical and clustering-based multipath routing. But, existent algorithms have many weaknesses such as: high overhead, security vulnerabilities, address-centric, low-scalability, permanent usage of optimal paths and severe resources' consumption. As a result, this paper is proposed an energy-aware, congestion-aware, location-based, data-centric, scalable, hierarchical and clustering-based multipath routing algorithm based on Numerical Taxonomy technique for homogenous WSNs. Finally, performance of the proposed algorithm has been compared with performance of LEACH routing algorithm; results of simulations and statistical-mathematical analysis are showing the proposed algorithm has been improved in terms of parameters like balanced resources' consumption such as energy and bandwidth, throughput, reliability and fault tolerant, accuracy, QoS such as average rate of packet delivery and WSNs' lifetime.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.152-159
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• 2016

This paper describes an offset and 1/f noise cancellation technique based hall sensor signal processor. The hall sensor outputs a hall voltage from the input magnetic field, which direction is orthogonal to hall plate. The two major elements to complete the hall sensor operation are: the one is a hall sensor to generate hall voltage from input magentic field, and the other one is a hall signal process system to cancel the offset and 1/f noise of hall signal. The proposed hall sensor splits the hall signal and unwanted signals(i.e. offset and 1/f noise) using a spinning current biasing technique and chopper stabilizer. The hall signal converted to 100 kHz and unwanted signals stay around DC frequency pass through chopper stabilizer. The unwanted signals are bloked by highpass filter which, 60 kHz cut off freqyency. Therefore only pure hall signal is enter the ADC(analog to dogital converter) for digitalize. The hall signal and unwanted signal at the output of an amplifer and highpass filter, which increase the power level of hall signal and cancel the unwanted signals are -53.9 dBm @ 100 kHz and -101.3 dBm @ 10 kHz. The ADC output of hall sensor signal process system has -5.0 dBm hall signal at 100 kHz frequency and -55.0 dBm unwanted signals at 10 kHz frequency.

• Journal of Sensor Science and Technology
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• v.7 no.5
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• pp.306-312
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• 1998

To develop the multi-channel fiber-optic sensor array system, two-channel TDM(Time Division Multiplexing) fiber-optic sensor array was constructed and characterized. The sensor array topology was Mach-Zehender ladder type and PMDI(Phase-Matched Differential Interferometer) technique was used to exploit the efficiency of the array signal processing. By using a synthetic heterodyne demodulation technique, outputs of the two channels were monitored simultaneously. The sensitivities of channel #1 and #2 were measured ${\sim}60{\mu}rad/\sqrt{Hz}$ and ${\sim}80{\mu}rad/\sqrt{Hz}$, respectively. Crosstalk of sensors in the array was found to be approximately -36dB. Based on the results, we could conclude that TDM Mach-Zehnder ladder type sensor array can be used to detect the acoustic signal with stability and efficiency of the sensor array.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.6
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• pp.15-21
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• 2009

The goal of wireless sensor networks is to collect sensing data on specific region over wireless communication. Sink node gathers all local sensing data, processes and transmits them to users who use sensor networks. Generally, senor nodes are low-cost, low power devices with limited sensing, computation and wireless communication capabilities. And sensor network applies to multi-hop communication on large-scale network. As neighboring sensor nodes have similar data, clustering is more effective technique for 'data-aggregation'. In cluster formation technique based on multi-hop, it is necessary that the number of cluster member nodes should be distributed equally because of the balance of cluster formation To achieve this, we propose a method to customize cluster member nodes for energy-efficiency in wireless sensor networks.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.641-659
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• 2010

Structural Health Monitoring (SHM) gradually becomes a technique for ensuring the health and safety of civil infrastructures and is also an important approach for the research of the damage accumulation and disaster evolving characteristics of civil infrastructures. It is attracting prodigious research interests and the active development interests of scientists and engineers because a great number of civil infrastructures are planned and built every year in mainland China. In a SHM system the sheer number of accompanying wires, fiber optic cables, and other physical transmission medium is usually prohibitive, particularly for such structures as offshore platforms and long-span structures. Fortunately, with recent advances in technologies in sensing, wireless communication, and micro electro mechanical systems (MEMS), wireless sensor technique has been developing rapidly and is being used gradually in the SHM of civil engineering structures. In this paper, some recent advances in the research, development, and implementation of wireless sensors for the SHM of civil infrastructures in mainland China, especially in Dalian University of Technology (DUT) and Harbin Institute of Technology (HIT), are introduced. Firstly, a kind of wireless digital acceleration sensors for structural global monitoring is designed and validated in an offshore structure model. Secondly, wireless inclination sensor systems based on Frequency-hopping techniques are developed and applied successfully to swing monitoring of large-scale hook structures. Thirdly, wireless acquisition systems integrating with different sensing materials, such as Polyvinylidene Fluoride(PVDF), strain gauge, piezoresistive stress/strain sensors fabricated by using the nickel powder-filled cement-based composite, are proposed for structural local monitoring, and validating the characteristics of the above materials. Finally, solutions to the key problem of finite energy for wireless sensors networks are discussed, with future works also being introduced, for example, the wireless sensor networks powered by corrosion signal for corrosion monitoring and rapid diagnosis for large structures.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.78-81
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• 2004

A technical performance of the coating depends greatly on the thickness of painting film or coating film. Therefore the confirmed report of the technique to measure accurately is essential to the coating film thickness for the assessment about a coating quality performance. In this paper, two gap sensors - eddy current gap sensor and capacitance gap sensor - which has a different operating principle were used to measure the thickness of a nonmagnetic substance coating film such as paint, enamel or ceramic that was coated on the metallic material. A capacitance gap sensor was used to measure the distance between the sensor head and a coating film and an eddy current gap sensor to measure the distance between the sensor head and a base metal. Then the thickness of a coating film was obtained by the difference of two measurement value. At this result, the suggested dual sensor can measure an arbitrary film thickness to be coated on a base metal as the measurement value of coating thickness exists accurately within the 2％ error.

• Proceedings of the Safety Management and Science Conference
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• 2009.04a
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• pp.445-449
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• 2009

Nowadays ubiquitous sensor network (USN) has been considered as a key technique in all kinds of industrial area. The main purpose of this study is to search and analyze systems in real industrial fields based on USN. USN technique has been applied into various industrial fields such as ground/underground management system, visitor counter system, monitoring system, unmanned vehicles system and so on. The result of this study will be fruitful not only for researches but also for practices in industrial fields related to USN.

• Smart Structures and Systems
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• v.13 no.1
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• pp.155-171
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• 2014

Various monitoring techniques are now available for structural health monitoring and Acoustic Emission (AE) is one of them. One of the major advantages of the AE technique is its capability to locate active cracks in structural members. AE crack locating approaches are affected by the signal attenuation and dispersion of elastic waves due to inhomogeneity and geometry of reinforced concrete (RC) members. In this paper, a novel technique is described based on signal processing and sensor arrangement to process multisensory AE data generated by the onset and propagation of cracks and is validated with experimental results from an in-situ load test. Considering the sources of uncertainty in the AE crack location process, a methodology is proposed to capture and locate events generated by cracks. In particular, the relationship between AE events and load is analyzed, and the feasibility of using the AE technique to evaluate the cracking behavior of two RC slab strips during loading to failure is studied.