{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,20]],"date-time":"2026-06-20T13:28:39Z","timestamp":1781962119207,"version":"3.54.5"},"reference-count":17,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2015,7,27]],"date-time":"2015-07-27T00:00:00Z","timestamp":1437955200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["2010-0028509"],"award-info":[{"award-number":["2010-0028509"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A fiber-optic cure monitoring system is proposed to measure curing status of composite structure such as a large scale wind turbine blade. The monitoring is based on the measurement of Fresnel reflectivity at the optical fiber\/epoxy resin interface. The refractive index of epoxy resin varies throughout curing stages, changing the Fresnel reflectivity. The curing status is decided by monitoring the reflected intensity variation. The usage of fiber Bragg grating (FBG) sensor helps to separate the temperature-induced cross effects. A Gaussian curve fitting algorithm was applied to FBG spectra which were distorted in curing procedure. The substantial measurement errors could be minimized by locating the centroids of the Gaussian curve-fitted spectra. From the experiments performed in various isothermal conditions, the proposed system successfully identified the onset of gelation and the completion of curing of epoxy resins.<\/jats:p>","DOI":"10.3390\/s150818229","type":"journal-article","created":{"date-parts":[[2015,7,28]],"date-time":"2015-07-28T02:12:37Z","timestamp":1438049557000},"page":"18229-18238","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":48,"title":["In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement"],"prefix":"10.3390","volume":"15","author":[{"given":"Umesh","family":"Sampath","sequence":"first","affiliation":[{"name":"Division of Electronics and Information Engineering, Chonbuk National University, Jeonju 561-756, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hyunjin","family":"Kim","sequence":"additional","affiliation":[{"name":"Division of Electronics and Information Engineering, Chonbuk National University, Jeonju 561-756, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dae-gil","family":"Kim","sequence":"additional","affiliation":[{"name":"Division of Electronics and Information Engineering, Chonbuk National University, Jeonju 561-756, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1736-0710","authenticated-orcid":false,"given":"Young-Chon","family":"Kim","sequence":"additional","affiliation":[{"name":"Division of Electronics and Information Engineering, Chonbuk National University, Jeonju 561-756, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Minho","family":"Song","sequence":"additional","affiliation":[{"name":"Division of Electronics and Information Engineering, Chonbuk National University, Jeonju 561-756, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2015,7,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"973","DOI":"10.1002\/pen.760291502","article-title":"A model for the thermal and chemoreological behavior of thermosets: 1. Processing of epoxy based composites","volume":"29","author":"Kenny","year":"1989","journal-title":"Polym. Eng. Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1016\/0266-3538(93)90109-T","article-title":"The principles of dielectric measurements for in situ monitoring of composite processing","volume":"49","author":"Mijovic","year":"1993","journal-title":"Compos. Sci. Technol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1805","DOI":"10.1002\/app.1994.070531310","article-title":"In situ cure monitoring of epoxy resins using fiber-optic Raman spectroscopy","volume":"53","author":"Lyon","year":"1994","journal-title":"J. Appl. Polym. Sci."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1591","DOI":"10.1109\/50.7920","article-title":"Fiber optic polymer cure sensor","volume":"6","author":"Afromowitz","year":"1988","journal-title":"Lightwave Technol. J."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"5635","DOI":"10.1364\/AO.34.005635","article-title":"Fiber-optic epoxy composite cure sensor. I. Dependence of refractive index of an autocatalytic reaction epoxy system at 850 nm on temperature and extent of cure","volume":"34","author":"Lam","year":"1995","journal-title":"Appl. Opt."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"270","DOI":"10.1016\/S0924-4247(00)00361-7","article-title":"An optoelectronic sensor for cure monitoring in thermoset-based composites","volume":"84","author":"Cusano","year":"2000","journal-title":"Sens. Actuators. A: Phys."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"781","DOI":"10.1109\/JSEN.2003.820319","article-title":"Optoelectronic refractive index measurements: Application to smart processing","volume":"3","author":"Cusano","year":"2003","journal-title":"IEEE Sens. J."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1088\/0964-1726\/11\/2\/308","article-title":"Real-time cure monitoring of smart composite materials using extrinsic Fabry-Perot interferometer and fiber Bragg grating sensors","volume":"11","author":"Leng","year":"2002","journal-title":"Smart Mater. Struct."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1016\/S0924-4247(99)00266-6","article-title":"Cure monitoring of smart composites using Fiber Bragg Grating based embedded sensors","volume":"79","author":"Murukeshan","year":"2000","journal-title":"Sens. Actutors A: Phys."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2205","DOI":"10.1364\/AO.46.002205","article-title":"Accuracy improvement in peak positioning of spectrally distorted fiber Bragg grating sensors by Gaussian curve fitting","volume":"46","author":"Lee","year":"2007","journal-title":"Appl. Opt."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"3273","DOI":"10.1016\/j.compscitech.2005.07.009","article-title":"Real time monitoring of cure and gelification of a thermoset matrix","volume":"66","author":"Antonucci","year":"2006","journal-title":"Compos. Sci. Technol."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Othonos, A., and Kalli, K. (1999). Fiber Bragg Gratings: Fundamentals and Applications in Telecommunications and Sensing, Artech house.","DOI":"10.1007\/978-1-4757-6079-8_2"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"6769","DOI":"10.3390\/s8106769","article-title":"Linear FBG temperature sensor interrogation with Fabry-perot ITU multi-wavelength reference","volume":"8","author":"Park","year":"2008","journal-title":"Sensors"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"415","DOI":"10.1016\/j.optlaseng.2010.11.011","article-title":"An optimized strain demodulation method based on dynamic double matched fiber Bragg grating filtering","volume":"49","author":"Jiang","year":"2011","journal-title":"Opt. Lasers Eng."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"312","DOI":"10.3807\/JOSK.2013.17.4.312","article-title":"A fiber laser spectrometer demodulation of fiber Bragg grating sensors for measurement linearity enhancement","volume":"17","author":"Kim","year":"2013","journal-title":"J. Opt. Soc. Korea"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1590\/S1516-14392005000100012","article-title":"Influence of aromatic amine hardeners in the cure kinetics of an epoxy resin used in advanced composites","volume":"8","author":"Costa","year":"2005","journal-title":"Mater. Res."},{"key":"ref_17","first-page":"1329","article-title":"Dielectric changes during the curing of epoxy resin based on the Diglycidyl Ether of Bisphenol A (DGEBA) with diamine","volume":"20","author":"Kim","year":"1999","journal-title":"Bull. Korean Chem. Soc."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/15\/8\/18229\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T20:49:46Z","timestamp":1760215786000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/15\/8\/18229"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2015,7,27]]},"references-count":17,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2015,8]]}},"alternative-id":["s150818229"],"URL":"https:\/\/doi.org\/10.3390\/s150818229","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2015,7,27]]}}}