• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.213-217
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• 1996

The electrochemical methods of early detection and analysis of corrosion related deterioration in concrete reinforcement structures are very useful techniques. The generally using procedure for corrosion monitoring of reinforced structures employs a method of half-cell potential measurement. Whilst the technique has provided a useful means of delineating areas of high or low corrosion risk, there are difficulties in its use and interpretation, particularly when assessing corrosion rates of reinforcement. The aim of this study is to describe the AC-impedance method being employed to monitor and assess corrosion rates, to estimate corrosion mechanism of reinfrocement in laboratory conditions. The AC-impedance monitoring technique applies a small amplitude(20mV) AC signal to embedded steel in concrete and reference electrode (Cu/$CuSo_4$). We obtained over a wide frequency range(10MHz~1mHz) to produce a complex plane plot or Nyquist plot.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2186-2188
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• 2000

A fiberoptic sensor using an SLD as a light source has been studied. The sensor system employs an intrinsic fiber Fabry-Perot interferometer as a sensing tip and a fiber Mach-Zehnder interferometer as a processing one. A free loading test for temperature application shows that the fiberoptic sensor has a wide-dynamic range as well as high resolution. Due to the inherent property of the optical fiber itself and the intrinsic Fabry-Perot interferometer. the fiberoptic sensor gives obvious benefits when it is applied to harsh environments to monitor some physical parameters such as temperature, strain, pressure and vibration.

• 반도체디스플레이기술학회지
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• 제7권1호
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• pp.23-27
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• 2008

Wireless sensor networks are emerging as a solution for a wide range of data gathering applications. The most difficult challenge for the design of sensor nodes is the need for significant reductions in energy consumption. The threshold methods which filter redundant and similar data can be used to save energy. In this paper, we propose the adaptive threshold method to effectively manage the energy in wireless sensor nodes. In the adaptive threshold method, wireless sensor nodes can change the thresholds dynamically as the sensing environments vary. The simulation results show that the adaptive threshold method works very effectively even when we experience the significant volatility in the data. This scheme can be used in order to monitor the malfunction in the equipment of semiconductor manufacturing line.

• 센서학회지
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• 제24권5호
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• pp.311-318
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• 2015

The excess use and generation of various toxic gases from many industrial complexes and plant facilities have increased the possibility of leakage or explosion accidents, which can cause fatal damage to human beings in the wide range of neighboring area. To prevent the exposure to the fatal toxic gases, it is very important to monitor the leakage of toxic gases using gas sensors in real time. Various types of gas sensors, which can be classified as semiconductor, electrochemical, optical, and catalytic combustion types according to the operating principles, have been developed. In this review, the operation principles of gas sensors are explained and the performance of those sensors is compared. The state-of-the-art gas sensor technologies developed by research institutes or companies are reviewed also.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 추계학술대회
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• pp.61-64
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• 1996

Currently many researches are going on a Picture Archiving and Communication System (PACS) which can handle a large number of image data very efficiently. However, the price of those systems are very expensive to a small and medium hospital. In this paper, we developed a PC based Mini-PACS at a low price with a high performance. The main components of the designed system are: Image processing and display for a diagnosis, Client/Server database management system, Multi-monitor display system, Connection through the World Wide Web with Common Gateway Interface.

• Journal of Electrical Engineering and Technology
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• 제5권1호
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• pp.140-145
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• 2010

The monitoring and the diagnosis of the faults in induction motors starting from the stator current are very interesting, since it is an accessible and measurable quantity. The spectral analysis of the stator current makes it possible to highlight the characteristic frequencies of the faults but in a wide frequency range depending on half the sampling frequency, making it very difficult to monitor on-line the faults. In order to facilitate the use of the relevant frequencies of machine faults we proposed the extraction of the frequency components using two methods, namely, the amplitude and the instantaneous frequency. The theoretical bases of these methods were presented and the results were validated on a test bench with an induction motor of 5.5 kw.

• Bulletin of the Korean Chemical Society
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• 제20권5호
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• pp.556-558
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• 1999

Lead-selective PVC membrane electrodes based on newly synthesized bis(crown ether)s containing 18-crown-6 moiety was prepared using standard PVC membrane composition. In order to monitor lead in environmental samples by lead sensor, especially good selectivity over alkali and alkaline earth metals has to be obtained. Thus, responses of the PVC membrane prepared with new bis(crown ether)s and Fluka ionophore V (crown ether) base to various cations include lead, alkali and alkaline earth metal ions were investigated for their use as a lead sensor. The polymeric liquid membrane based on trans-1 8-crown-6 ether exhibits the best overall potentiometric performances as a lead-selective electrode in terms of a wide linear dynamic range (between 10-6 and 10-2 M, Pb2+), excellent detection limit (less than 10-6 M) and good durability within limited error. The preferences of lead over other cations, such as Ag+, Hg2+, Na+, Ca2+ and even K+ in the aforementioned electrode are much better than the Fluka ionophore V system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.73-78
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• 2008

There has been need for safety monitoring systems for the social infrastructures. These infrastructures are subject to degradation over time, reduced functionality, and loss of functionality as a result of factors such as a wide variety of installation environments, natural disasters, and nearby work. Therefore, it is necessary to perform appropriate inspections, repairs, and renovations to ensure safe and efficient maintenance and operation. This paper introduces the example of the development of the safety monitoring system for operating railway tunnel. Tunnel profile measuring system using laser beam, crack gauges, accelerometer and a pluviometer were implemented to monitor the safety of a deteriorated tunnel. The measured data were transferred through wireless network and analyzed in real time. The safety criteria for tunnel stabilities and train operations are also discussed.

• 한국자기공명학회논문지
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• 제23권2호
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• pp.51-55
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• 2019

Quantum dot (QD) is an emerging novel nanomaterial that has wide applicability and superior functionality with relatively low cost. Nuclear magnetic resonance (NMR) spectroscopy has been contributed to elucidate various features of QDs and to improve their overall performance. In particular, NMR spectroscopy becomes an essential analytical tool to monitor and analyze organic ligands on the QD surface. In the present mini-review, application of NMR spectroscopy as a superb methodology to appreciate organic ligands is discussed. In addition, it was recently noted that ligands exert rather greater influence on diverse features of QDs than our initial anticipation, for which contribution of NMR spectroscopy is briefly reviewed.

• Structural Engineering and Mechanics
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• 제85권6호
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• pp.743-753
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• 2023

Piezoelectricity is defined as the ability of certain materials to produce electric signals when mechanically stressed or to deform when an electrical potential is applied. Piezo technology is becoming increasingly crucial as intelligent devices use vibration sensors to detect vibrations in consumer electronics, the automotive industry, architectural design, and other applications. A wide range of applications is now possible with piezoelectric sensors, such as skin-attachable devices that monitor health and detect diseases. In this article, copper nanoparticles are used in the piezoelectric sensor as the driving agent of the magnetic field. Magnetic nanocatalysts containing copper nanoparticles are used due to their cheapness and availability. Considering that the increase of the electric field acting on the piezoelectric increases the damping (As a result, damping materials reduce radiation noise and increase material transfer losses by altering the natural vibration frequency of the vibrating surface). Among the advantages of this method are depreciating a significant amount of input energy using high energy absorption capacity and controlling slight vibrations in the sensors.