• Korean Journal of Optics and Photonics
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• v.21 no.5
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• pp.190-194
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• 2010

A hybrid grating sensing device based on a side-polished fiber Bragg grating (FBG) with a polymer overlay is proposed for simultaneous measurement of external refractive index and temperature. The side-polished FBG, which is insensitive to ambient index change, is utilized for detecting temperature variation, and the polymer overlay is coated on the side-polished FBG for measurement of ambient index change. The temperature sensitivities of the side-polished FBG and the polymer overlay were measured to be 0.01 nm/$^{\circ}C$ and -0.58 nm/$^{\circ}C$, respectively, in a temperature range from $30^{\circ}C$ to $100^{\circ}C$. The ambient index sensitivities of the polymer overlay were measured to be 498.8 nm/RIU in an ambient index range from 1.33 to 1.39, 694.9 nm/RIU from 1.39 to 1.42, and 1312 nm/RIU from 1.42 to 1.44.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.31-39
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• 2011

More than sixty percentage of highway in South Korea were constructed by concrete pavements and more than half of the concrete pavements were twenty years or older. Maintenance and rehabilitation of aged cement concrete pavements required early transportation opening due to difficulty of preparing bypass roads, given South Korea's transportation condition and so far, mostly asphalt concrete overlay has been used. However, asphalt concrete pavement maintenance and rehabilitation is costly because of early damage and at the same time, it causes inconvenience to the road users. Recently, as an effective method of rehabilitation for aged cement concrete pavement, bonded concrete overlay is being attempted. Therefore, utilizing various data on year-by-year basis is needed to rationally analyze of the damage on asphalt concrete overlay and bonded concrete overlay is necessary. However, in South Korea database of Serviceability damage on asphalt concrete overlay and bonded concrete overlay does not exist. In this research, performance is evaluated by the LTPP (Long Term Pavement Performance) Data of U.S.A, which accumulated various damage data of asphalt concrete overlay and bonded concrete overlay. However, the pattern distress of asphalt concrete overlay and bonded concrete overlay are different. Therefore, the pavement distress data of each section is collected into database and distress are calculated PCI(Pavement Condition Index) in order to compare life of asphalt concrete overlay and bonded concrete overlay.

• International Journal of Highway Engineering
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• v.19 no.6
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• pp.97-103
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• 2017

PURPOSES : In this study, the pavement condition of non-mill-and-overlay and mill-and-overlay on deteriorated concrete pavement was compared. In addition, the suitable time to perform the initial overlay was investigated. METHODS : The condition of the pavement sections that were not additionally overlaid on non-mill-and-overlay or mill-and-overlay on deteriorated concrete pavements was investigated according to overlay pavement age. The condition of non-mill-and-overlay and mill-and-overlay sections of expressway route 25, which has more information on overlay history than other routes, was compared according to the number of times of overlay. The relation between the concrete pavement condition just before the overlay and the number of times of overlay was investigated for the non-mill-and-overlay and mill-and-overlay sections for which the first overlay was performed in the same year. RESULTS : The pavement condition of the non-mill-and-overlay sections was better than that of the mill-and-overlay sections, showing higher Highway Pavement Condition Index(HPCI) regardless of overlay pavement age. The number of reflection crackings of the non-mill-and-overlay sections was smaller than that of the mill-and-overlay sections. As a result of observing the cores obtained from the overlay sections, the proportion of the deteriorated non-mill-and-overlay sections was smaller than that of the mill-and-overlay sections. The SD measured just before the overlay on the concrete pavement for which additional overlay was not performed was smaller than that for which additional overlay was performed regardless of the milling of the concrete slab surface. The HPCI of the concrete pavement for which overlay was performed just once was higher than that for which overlay was performed more than one time. CONCLUSIONS : Accordingly, it was concluded that the condition of the non-mill-and-overlay sections was better than that of the mill-and-overlay sections. In addition, the better the condition of concrete pavement just before the initial overlay, the longer the duration of the overlay effect.

• International Journal of Highway Engineering
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• v.16 no.1
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• pp.1-10
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• 2014

PURPOSES : This study aimed to evaluate the long-term performance of bonded concrete overlay in Korean Highway, and factors influencing the performances. METHODS : The evaluation for long-term performance of bonded concrete overlay is investigated based on the following study : i) The pavement distress of number of bonded concrete overlay sections in Korean highway are collected through field measurement, and PCI for each section is calculated. ii) Performance of LTPP data of bonded concrete overlay sections in U.S.A is analysed. And it is compared with bonded concrete overlay of Korean highway. iii) An analysis of the factors influencing to long-term performance of bonded concrete overlay is investigated. RESULTS : Performance analysis was confirmed that the overlay thickness was affecting significantly on the Bonded Concrete Overlay life. The comparison of LTPP data(U.S.A) and field measurement data(Korean) was showed. CONCLUSIONS : It was showed that the performance of Korean bonded concrete overlay is relatively lower than that of the bonded concrete overlay in U.S.A. The cause of lower performance can be explained by the lack of overlay thickness.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.908-910
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• 2003

In this paper the extraction method for the best suitable green vegetation area in urban area, Daegu, Korea, was developed using satellite images (1994, 1999, Landsat TM). For this, the GIS overlay analysis of GVI (Green Vegetation Index), SBI (Soil Brightness index), NWI (None-Such wetness Index) was performed to estimate the best suitable green vegetation area. Also, the statistical documents, algorithm and Tasseled-Cap index were used to recognize the change of land cover such as cultivation area, urban area, and damaged area. Through the result of this study, it is possible to monitor the large sized reclamation of land by drainage or damaged area by forest fires. Moreover, information with the change of green vegetation and the status of cultivation by GVI, but also moisture content by percentage by NWI and surface class by SBI can be obtained.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.207-221
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• 2011

More than sixty percentage of highway in South Korea were constructed by concrete pavements and more than half of the concrete pavements were twenty years or older. The most of highway have difficulty in providing detour due to the traffic and road condition of South Korea. So far, asphalt concrete has been used for the overlay of aged cement concrete pavement. However, the frequent early damage and maintenance of typical asphalt overlay due to repetitive maintenance causes inconvenience of road users and expensive costs. It is necessary to investigate the factors affecting the performance of asphalt concrete overlay to improve the performance of asphalt overlay. However, the performance data of asphalt concrete overlay in South Korea does not exist. In this research, to investigate on the factors affecting the life of asphalt concrete overlay was attempted based on statistical analysis of the performance data of asphalt concrete overlay included in LTPP (Long-Term Pavement Performance) Database of U.S.A.

• Journal of Broadcast Engineering
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• v.2 no.1
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• pp.36-44
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• 1997

We propose 3D perspective display using elevation matrix data with 2D information overlay. This algorithm is based on ID scan-line method and we used color index of the newly developed raster map, VRRG(Vector Restored Raster Graphics). The proposed method allows the fast generation of perspective view of 3D data with 2D overlay and the fast selective display of the features of 2D overlay.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4D
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• pp.555-564
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• 2011

More than sixty percentages of the highway constructed by concrete pavements in South Korea and over half of the concrete pavements were twenty years or older. The most of South Korea road is hard to provide a bypass in conditions of network of roads. Asphalt concrete overlay has been used for the overlay of aged concrete pavement. However, the cost of maintenance and rehabilitation in an asphalt overlay is expensive by early damage. Therefore, bonded concrete overlay was recently attempted in South Korea as an alterative method of rehabilitation for aged concrete pavement. Hence, it needed to investigate the factors to find performance of the bonded concrete overlay life. However, there is no performance data of the concrete overlay in South Korea. This study was to make a database of an affecting of the pavement life and draws statistical analysis of the performance data on the LTPP (Long Term Pavement Performance) database of U.S.A.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.28-33
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• 2004

An in-line fiber coupler, based on side-polished single-mode fibers covered with an intermediate coupling layer and a planar waveguide, is analyzed by modeling the interaction region as an equivalent multi-layered planar waveguide. The reflectance for the multi-layered structure with and without buffer layer is illustrated as a function of the refractive index and thickness of the overlay waveguides. When the refractive index of the overlay waveguides is greater than that of the fiber core, the conditions for the intermediate coupling layer to increase the power coupling from the fiber to the overlays is also explained. Through the experimental results using a LiNbO$_3$planar waveguide, we show that the theoretical analysis is reasonable and in good agreement with the measured values.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.475-480
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• 2003

Latex modification of concrete provides the material with higher flexural strength. This increase in flexural strength can attribute to the crack-arresting action of polymer in concrete, and also to the bonding they provide between the matrix and aggregates. This experimental study presents the fracture behavior of 12 flexural reinforced concrete beams repaired or strengthened by latex-modified concrete with the main experimental variables such as overlay thickness, strength thickness, and shear reinforcement. The results are as follow: All beam specimens having shear reinforcement were failed by delamination rupture at concrete interface at about 80% of ultimate loading after flexural cracking. All specimens overlayed and strengthened by latex-modified concrete (LMC) showed higher ultimate flexural strength than OPC control specimen, but lower than LMC control specimen. This increase in flexural strength could attribute to the high bonding they provide between the matrix and aggregates. All specimens except two shear unreinforced showed quite similar and consistent displacement behavior. The effect of overlay and strength thickness on the load-displacement relationship were a small at this study.