• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.250-253
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• 2001

Recently, based on the smart structure concept, optical fiber sensors have been increasingly applied to monitor the various engineering and civil structural components. Repairs based on adhesively bonded fiber reinforce composite patches are more structurally efficient and much less damaging to the parent structure than standard repairs based on mechanically fastened metallic patches. As a result of the high reinforcing efficiency of bonded patches fatigue cracks can be successfully repaired. However, when such repairs are applied to primary structures, it is needed to demonstrate that its loss can be immediately detected. This approach is based on the "smart patch" concept in which the patch system monitors its own health. The objective of this study is to evaluate the potentiality of application of transmission-type extrinsic Fabry-Perot optical fiber sensor (TEFPI) to the monitoring of crack growth behavior of composite patch repaired structures. The sensing system of TEFPI and the data reduction principle for the detection of crack detection are presented. Finally, experimental results from the tests of center-cracked-tension aluminum specimens repaired with bonded composite patch is presented and discussed.

• Journal of IKEEE
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• v.20 no.4
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• pp.367-372
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• 2016

We Designed and Conduct a study on the basic intrusion detection research for outside intruder, which can determine the location and the weight of an intruder into infrastructure, by using Fiber-Optic ROTDR( Rayleigh Optical Time Domain Reflectometer) sensor, which are buried in the sand, were prepared to respond the intruder effects. The signal of ROTDR was analyzed to confirm the detection performance. The weight could be detected as 4 grades, such as 20kg, 40kg, 60kg, and 80kg. which used long distance fiber for intruder detection on wide area. This sensor was possible for application of real-time monitoring of infrastructures.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06c
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• pp.36-40
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• 2008

SIMS manages data for various spatial and non-spatial as integral management system to support space information administration environment and support several application works. Without being limited to spatial data that existent spatial Data Mining question language advances handling in this paper, did so that can find useful information from various data connected with automatically data collection, artificial satellite side upside service, remote sensing, GPS. Mobile Computing and data about Spatio-Temporal. Also, we designed spatial Data Mining query language that support a spatial Data Mining exclusive use system based on SIMS.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.7
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• pp.418-423
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• 2000

The fiber Fabry-Perot interferometric(FFPI) sensor is well known in the field of industrial diagnosis due to its outstanding properties such as tiny size, simple and rugged structure, and easy interrogation. As other fiber interferometric sensors, it also suffers from ambiguous output caused by highly periodic feature in its optical transfer function. In most cases, the ambiguity leads to relatively short dynamic operating range and long processing time during power-on reset, which limits its application to some specific fields requiring very high resolution. In this paper a method based on double sensing scheme was proposed to overcome the above difficulty. By employing a fringe selection auxiliary FFPI sensor the original FFPI sensor can identify its true position on the phase domain. The performance test with 10mm FFPI sensor and a thermocouple temperature sensor for reference shows wide dynamic range 0-900$\ell$ keeping a reasonable resolution of 0.1$\ell$ over the entire range.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.1-4
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• 2009

Construction automation and robotics are being introduced as an efficient alternative to overcome troubles caused by lack of skilled labors. To accomplish effective automated construction system, design for automation(DFA) should be performed in parallel with the development of core technologies such as control and sensing of robots. In Korea, the development of robotic crane-based construction automation(RCA) system is progressing, and the research group has recently developed newly designed steel joint to improve the efficiency of the system. However, performance of the new system should be examined prior to its application on construction sites. Therefore, This study analyzed performance of the new steel frame focused on its constructibility by carrying out mock-up test. As a result, the steel frame satisfied the standards of allowable stress and deflection. It also enables to reduce the time for installation.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.394-399
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• 2002

In this paper, Multisource data classification methods based on Bayesian formula are considered. For this decision fusion scheme, the individual data sources are handled separately by statistical classification algorithms and then Bayesian fusion method is applied to integrate from the available data sources. This method includes the combination of each expert decisions where the weights of the individual experts represent the reliability of the sources. The reliability measure used in the statistical approach is common to all pixels in previous work. In this experiment, the weight factors have been assigned to have different value for all pixels in order to improve the integrated classification accuracies. Although most implementations of Bayesian classification approaches assume fixed a priori probabilities, we have used adaptive a priori probabilities by iteratively calculating the local a priori probabilities so as to maximize the posteriori probabilities. The effectiveness of the proposed method is at first demonstrated on simulations with artificial and evaluated in terms of real-world data sets. As a result, we have shown that Bayesian statistical fusion scheme performs well on multispectral data classification.

• Journal of the Korean Geophysical Society
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• v.7 no.4
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• pp.269-276
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• 2004

Optical fiber sensors have shown a potential to serve real time health monitoring of the structures. They can be easily embedded or attached to the structures and are not affected by the electro-magnetic field. Furthermore, they have the flexibility of the sensor size and very highly sensitive. In this study, we conducted several laboratory and field tests using a novel optical sensor based on Brillouin scattering. One of the advantages of this technique is that the bare fiber itself acts as sensing element without any special fiber processing or preparation. Test results have shown that BOTDR can be a great solution for sensor systems of Civil Engineering Smart Structures.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.220-223
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• 2008

A camera system for the satellite application performs the mission of observation by measuring radiated light energy from the target on the earth. As a development stage of the system, the signal level analysis by estimating the number of electron collected in a pixel of an applied CCD is a basic tool for the performance analysis like SNR as well as the data path design of focal plane electronic. In this paper, two methods are presented for the calculation of the number of electrons for signal level analysis. One method is a quantitative assessment based on the CCD characteristics and design parameters of optical module of the system itself in which optical module works for concentrating the light energy onto the focal plane where CCD is located to convert light energy into electrical signal. The other method compares the design\ parameters of the system such as quantum efficiency, focal length and the aperture size of the optics in comparison with existing camera system in orbit. By this way, relative count of electrons to the existing camera system is estimated. The number of electrons, as signal level of the camera system, calculated by described methods is used to design input circuits of AD converter for interfacing the image signal coming from the CCD module in the focal plane electronics. This number is also used for the analysis of the signal level of the CCD output which is critical parameter to design data path between CCD and A/D converter. The FPE(Focal Plane Electronics) designer should decide whether the dividing-circuit is necessary or not between them from the analysis. If it is necessary, the optimized dividing factor of the level should be implemented. This paper describes the analysis of the electron count of a camera system for a satellite application and then of the signal level for the interface design between CCD and A/D converter using two methods. One is a quantitative assessment based on the design parameters of the camera system, the other method compares the design parameters in comparison with those of the existing camera system in orbit for relative counting of the electrons and the signal level estimation. Chapter 2 describes the radiometry of the camera system of a satellite application to show equations for electron counting, Chapter 3 describes a camera system briefly to explain the data flow of imagery information from CCD and Chapter 4 explains the two methods for the analysis of the number of electrons and the signal level. Then conclusion is made in chapter 5.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1423-1444
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• 2022

In this study, the sensitivity of the mid-infrared radiance to atmospheric and surface factors was analyzed using the radiative transfer model, MODerate resolution atmospheric TRANsmission (MODTRAN6)'s simulation data. The possibility of retrieving the land surface temperature (LST) using only the mid-infrared bands at night was evaluated. Based on the sensitivity results, the LST retrieval algorithm that reflects various factors for night was developed, and the level of the LST retrieval algorithm was evaluated using reference LST and observed LST. Sensitivity experiments were conducted on the atmospheric profiles, carbon dioxide, ozone, diurnal variation of LST, land surface emissivity (LSE), and satellite viewing zenith angle (VZA), which mainly affect satellite remote sensing. To evaluate the possibility of using split-window method, the mid-infrared wavelength was divided into two bands based on the transmissivity. Regardless of the band, the top of atmosphere (TOA) temperature is most affected by atmospheric profile, and is affected in order of LSE, diurnal variation of LST, and satellite VZA. In all experiments, band 1, which corresponds to the atmospheric window, has lower sensitivity, whereas band 2, which includes ozone and water vapor absorption, has higher sensitivity. The evaluation results for the LST retrieval algorithm using prescribed LST showed that the correlation coefficient (CC), the bias and the root mean squared error (RMSE) is 0.999, 0.023K and 0.437K, respectively. Also, the validation with 26 in-situ observation data in 2021 showed that the CC, bias and RMSE is 0.993, 1.875K and 2.079K, respectively. The results of this study suggest that the LST can be retrieved using different characteristics of the two bands of mid-infrared to the atmospheric and surface conditions at night. Therefore, it is necessary to retrieve the LST using satellite data equipped with sensors in the mid-infrared bands.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.1102-1108
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• 2008

Wearable physiological signal monitoring systems are regarded as an important sensing unit platforms in ubiquitous/mobile healthcare application. In this paper, we suggested the modified bipolar electrodes implemented on the portable heart activity monitoring system, which minimized the distance of electrodes formed on a attachable pad. The proposed electrode configuration is useful in mobile measurement environments, but has a disadvantage of reduced amplitude of the heart action potential. In order to overcome the shortcoming of the suggested electrode configuration, we implemented the amplifying circuit to increase the signal-gain and decrease the artifacts. For evaluations, we analyzed the specificity of measured cardiography using the proposed electrodes through the comparing of heart activity monitoring system with standard clinical ECG(lead2) by pearson correlation coefficients. The result showed that the average correlation coefficient is $0.903{\pm}0.036,\;0.873{\pm}0.072$ at V3, V4 chest lead position, respectively. Thus, the modified bipolar electrode is quite suitable to monitor the electrical activity of the heart in the situation of the mobile environment, and could be considered having high similarity with standard clinical ECG.