• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3307-3311
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• 2013

A new fiber optical sensor was developed for the determination of 2,4-dichlorophenol (DCP). The sensor was based on DCP oxidation by oxygen with the catalysis of iron(III) tetrasulfophthalocyanine (Fe(III)PcTs). The optical oxygen sensing film with $Ru(bpy)_3Cl_2$ as the fluorescence indicator was used to determine the consumption of oxygen in solution. A lock-in amplifier was used for detecting the lifetime of the oxygen sensing film by measuring the phase delay change of the sensor head. The different variables affecting the sensor performance were evaluated and optimized. Under the optimal conditions (i.e. pH 6.0, $25^{\circ}C$, Fe(III)PcTs concentration of 0.62 mg/mL), the linear detection range and response time of the sensor are $1.0{\times}10^{-6}-9.0{\times}10^{-6}$ mol/L and 250 s, respectively. The sensor displays high selectivity, good repeatability and stability, and can be used as an effective tool in analyzing DCP concentration in practical samples.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.6
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• pp.421-430
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• 2005

Brillouin time-domain analysis in optical fibres is a novel technique making possible a distributed measurement of temperature and strain over long distance and will deeply modify our view about monitoring large structures, such as dams, bridges, tunnels and pipelines, Optical fibre sensing will certainly be a decisive tool for securing dangerous installations and detecting environmental and industrial threats.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.278-282
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• 1995

We developed a part of storke sensing cylinder using magnetic sensor and estimated is performance. In this paper, for the performance estimation of stroke sensing cylinder. We consist of hydrallic system using solenoid valve with ON/OFF motion. In order to the control of solenoid valve for the position control of cylinder rod, PWM (Pulse Width Modulation) method which modulates time pulse width in proportion to error was used. A performance of cylinder rod with magnetic scales was evaluated by its hydraulic system.

• Journal of electromagnetic engineering and science
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• v.11 no.4
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• pp.250-256
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• 2011

This paper applies a compressed algorithm to improve the spectrum sensing performance of cognitive radio technology. At the fusion center, the recovery error in the analog to information converter (AIC) when reconstructing the transmit signal from the received time-discrete signal causes degradation of the detection performance. Therefore, we propose a subspace pursuit (SP) algorithm to reduce the recovery error and thereby enhance the detection performance. In this study, we employ a wide-band, low SNR, distributed compressed sensing regime to analyze and evaluate the proposed approach. Simulations are provided to demonstrate the performance of the proposed algorithm.

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.309-310
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• 2008

Polymer optical waveguides are fabricated with high-index materials deposited to strengthen exciations of evanescent field whose birefringence is utilized for optical sensing. Optical sensing properties are examined as a function of time, using different types of analyte solutions to extract noise-free signal induced by evanescent field birefringence. It is observed that sensing signal can be free of initial noise that may obscure real signal recognition, when glycerol is used for sensing characterization, due to slow accumulation process following adsorption of analyte material onto the sensing surface of the waveguide.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.507-515
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• 2002

Remote Sensing Monitoring and Loss Estimated System of Flood Disaster based on GIS is an integrated system comprised flood disaster information receiving and collection, flood disaster simulation, and flood disaster estimation. When the system receives and collects remote sensing monitoring and conventional investigation information, the distributional features of flood disaster on space and time is obtained by means of image processing and information fusion. The economic loss of flood disaster can be classified into two pus: direct economic loss and indirect economic loss. The estimation of direct economic loss applies macroscopic economic analysis methods, i.e. applying Product (Industry and Agriculture Gross Product or Gross Domestic Product - GDP) or Unit Synthetic Economic Loss Index, direct economic loss can be estimated. Estimating indirect economic loss applies reduction coefficient methods with direct economic loss. The system can real-timely ascertains flood disaster and estimates flood Loss, so that the science basis fur decision-making of flood control and relieving disaster may be provided.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1052-1054
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• 2003

RAZAKSAT is a second micro-satellite mission by Malaysian Satellite Program and is expected for launch in June 2004. Designed to orbit the earth at low-equatorial orbit, RAZAKSAT will meet Malaysia’s immediate needs to rapid data acquisition (real time and more repetitions) to address many operational issues of remote sensing applications, which require availability of current data sets. RAZAKSAT will be among the first remote sensing satellite to orbit the earth at low inclination along the equator, 9$^{\circ}$ with 685km altitude, hence, allows optimal geographical information and environment change within equatorial region be observed with a unique revisit characteristics. The satellite primary payload is MAC, a push-broom type camera with 2.5m of ground sampling distance (GSD) in panchromatic band and 5m of GSD in four multi-spectral bands. This paper describes on the variation of illumination anticipated from simulated RAZAKSAT image, examine its implication to its ground leaving radiances for major applications.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1346-1348
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• 2003

In this paper, the interferometric coherence was estimated and the amplitude intensity was extracted using the repeat-pass interferometric data, acquired by European Remote Sensing Satellite 1 and 2. Then discrimination and classification of surface land types in Zhangjiakou test site, Hebei Province were carried out based on the coherence estimation and the intensity extraction. Seven types of land were discriminated and classified, including in two different types of meadows, woodland, dry land, grassland, steppe and water body. The backscatter and coherence characteristics of these land types on the multi-temporal images were analyzed, and the change of surface features with time series was also discussed.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.3
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• pp.282-289
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• 2010

Most nondestructive testing techniques require good contact between the sensor and tested concrete surface to obtain reliable data. But the surface preparation is often very time and labor consuming due to the rough surface or limited access of concrete structures. One approach to speed up the data collection process is to eliminate the need for physical contact between the sensor and tested structure. Non-contact air-coupled sensing technique can be a good solution to this problem. An obvious advantage of the non-contact air-coupled sensing technique is which can greatly speed up the data collection in field and thus the damage detection process can be completed very rapidly. In this article, recent developments in non-contact air-coupled sensing technique for rapid detection of damages in concrete structures are summarized to evoke interest, discussion and further developments on this technique to a NDT research community in Korea. It is worth noting that the works in this article have been published in the types of thesis, proceedings, and journals. All published sources are cited in the text and listed in reference.

• Geomechanics and Engineering
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• v.24 no.4
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• pp.337-348
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• 2021

Brillouin Optical Frequency Domain Analysis (BOFDA) is a distributed fiber optic sensing (DFOS) technique that has unique advantages for performance monitoring of piles. However, the complicated production process and harsh operating environment of offshore PHC pipe piles make it difficult to apply this method to pile load testing. In this study, sensing cables were successfully pre-installed into an offshore PHC pipe pile directly for the first time and the BOFDA technique was used for in-situ monitoring of the pile under axial load. High-resolution strain and internal force distributions along the pile were obtained by the BOFDA sensing system. A finite element analysis incorporating the Degradation and Hardening Hyperbolic Model (DHHM) was carried out to evaluate and predict the performance of the pile, which provides an improved insight into the offshore pile-soil interaction mechanism.