• Journal of the Optical Society of Korea
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• v.12 no.3
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• pp.152-156
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• 2008

This paper reports a fiber-optic temperature sensor using a single mode fused fiber coupler incorporating a thermo-optic external medium. The spectral transmission was altered by changing the refractive index of the external thermo-optic medium. A theoretical and experimental investigation was carried out with the aim of achieving high sensitivity. The measured sensitivity for the environmental temperature was as high as -1.5 $nm/^{\circ}C$.

• Journal of Sensor Science and Technology
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• v.22 no.2
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• pp.95-99
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• 2013

We proposed and demonstrated a fiber optic sensor for detecting the thermo-optic coefficient of a liquid, based on a cascade of two different FBGs. One of the two FBGs was etched, and its cladding was removed, for evanescent wave coupling with an external liquid. The Bragg wavelength of the non-etched FBG was used as a reference for the temperature of the surrounding liquid. The refractive index (RI) and thermo-optic (T-O) coefficient of a liquid can be detected from the difference between the Bragg wavelengths of the two FBGs, and the variation of the difference in accordance with temperature.

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.367-374
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• 2014

In this study, skin permeation enhancement was confirmed by designing it to have a structure and composition similarity to the intercellular lipids that improve miscibility with skin by cross-linked lipids poloxamer. The cross-linked lipids poloxamer was synthesized and analyzed by 1H NMR that structure dose had conjugated pluronic with ceramide3. Active component is released by modification of liquid crystal structure because PPO part, large-scale molecule block of pluronic, has hydrophobic nature at skin temperature of $35^{\circ}C$. Conjugated pluronic with ceramide3 was synthesized using Pluronic F127 and p-NPC (4-nitrophenyl chloroformate) at room temperature yielded 89%. Pluronic(Ceramide 3-conjugated Pluronic) was synthesized by reaction of p-NP-Pluronic with Ceramide3 and DMAP. The yield was 51%. This cross-linked lipids poloxamer was blended and dissolved at isotropic state with skin surface lipids, phospholipid, ceramide, cholesterol and anhydrous additive solvent. Next step was preceded by ${\alpha}$-Transition at low temperature for making the structure of Meso-Phase Lamella, and non-hydrous skin analogue liquid crystal using thermo-sensitivity smart sensor, lamellar liquid crystal structure through aging time. For confirmation of conjugation thermo-sensitivity smart sensor and non-hydrous skin analogue liquid crystal, structural observation and stability test were performed using XRD(Xray Diffraction), DSC(Differential Scanning Calorimetry), PM (Polarized Microscope) And C-SEM (Cryo-Scanning Electron Microscope). Thermo-sensitivity observation by Franz cell revealed that synthesized smart sensor shown skin permeation effect over 75% than normal liquid crystal. Furthermore, normal non-hydrous skin analogue liquid crystal that not applied smart sensor shown similar results below $35^{\circ}C$ of skin temperature, but its effects has increased more than 30% above $35^{\circ}C$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.7
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• pp.542-548
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• 2008

A thermal mass air flow sensor (MAFS), which consists of a micro-heater and thermo-resistive sensors on the silicon-nitride ($Si_3N_4$) thin membrane structure, is micro-fabricated by MEMS processes. Two thermo-resistive temperature sensors are located at $100{\mu}m$ upstream and downstream from the micro-heater respectively. The thermal characteristics are measured to find the best measurement indicator. The micro-heater is operated under constant power condition, and four flow indicators are investigated. The normalized temperature indicator shows good physical meaning and is easy to use in practice. It is found that the configurations and heating power of thermal-resistive elements are the dominant factors to determine the range of the flow measurement in the MAFS with higher sensitivity and accuracy.

• International Journal of Aeronautical and Space Sciences
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• v.3 no.2
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• pp.24-30
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• 2002

This paper demonstrates a comparison of linear and nonlinear analyses for thermo-optic effects of optical temperature sensor based on the etched silica-based planar waveguide Bragg grating. Topics include theoretical analyses and experiment of the etched planar waveguide Bragg grating optical temperature sensor. Theoretical models with nonlinear than linear temperature effect for the grating response based on waveguide and plate deformation theories agree with experiments to within acceptable tolerance.

• Journal of Sensor Science and Technology
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• v.15 no.4
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• pp.263-268
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• 2006

We have demonstrated a highly sensitive temperature sensor using an etched single mode fiber with a thermally expanded core region. Large core size of thermally expanded core facilitates access to evanescent wave by the wet etching. The etched region was surrounded by a low dispersive external medium with high thermo-optic coefficient. Due to the large difference between the dispersion property of the fiber and that of the external medium, the device reveals a cut-off properties at spectral region. The cut-off wavelength was shifted by the variations of the environmental temperatures because of thermo-optic effect of the external medium. The sensitivity of the fabricated device was found to be $45nm/^{\circ}C$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.2049-2054
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• 2006

This paper demonstrates a comparison of linear and nonlinear analyses for thermo-optic effects of optical temperature sensor based on the etched silica-based planar waveguide Bragg grating. Topics include theoretical analyses and experiment of the etched planar waveguide Bragg grating optical temperature sensor, Theoretical models with nonlinear than linear temperature effect for the grating response based on waveguide and plate deformation theories agree with experiments to within acceptable tolerance.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.230-236
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• 1998

Thermal environment of greenhouse was investigated by thermo-tracer in this study. The Thermo-tracer is a high-sensitivity infrared thermometer of non-contact type. The infrared energy emitted from the measured object is converted into an electrical signal by the detector(HgCdTe) and display as a color or black & white thermal image by way of optical scanning, The experiment was conducted for Venlo-type greenhouse with pad & fan system. The temperature difference between measured by Thermo-trace and measured by HOBO sensor is maximum 0.8$^{\circ}C$. Thermo-trace is possible to use for the thermal environment analysis and diagnosis of a cooling and heating system of greenhouse.

• Korean Journal of Optics and Photonics
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• v.13 no.6
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• pp.467-472
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• 2002

In this paper, we propose a polarization-insensitive temperature sensor using a thermo-optic effect of the upper and (or) lower cladding of a planar waveguide in contact with a side-polished fiber. A microscope cover glass with thickness of a 170 ${\mu}{\textrm}{m}$ is adopted as an overlay waveguide because this waveguide opposes sudden temperature change and ensures polarization-insensitive responses. The measured polarization-dependence loss is less than 0.3 dB. The temperature can be detected as a result of the shift in coupling wavelength of the sensor. We investigate the shift in coupling wavelength as a function of the temperature variation with respect to the different thermo-optic coefficients of lower and upper claddings. We also show that the temperature sensitivity of the device can be easily controlled by the thermo-optic coefficients of lower and upper claddings of the overlay waveguide.

• Journal of the Optical Society of Korea
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• v.17 no.3
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• pp.231-236
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• 2013

We present both theoretically and experimentally the thermo-optic characteristics of micro-structured optical fiber (MOF) filled with mixed liquid. The performance of MOF depends on the efficient interaction between the fundamental mode of the transmitted light wave and the tunable thermo-optic materials in the cladding. The numerical simulation indicates that the confinement loss of MOF presents higher temperature dependence with higher air-filling ratios $d/{\Lambda}$, longer incident wavelength and fewer air holes in the cladding. For the 4cm liquid-filled grapefruit MOF, we demonstrate from experiments that different proportions of solutions lead to tunable temperature sensitive ranges. The insertion loss and the extinction ratio are 3~4 dB and approximate 20 dB, respectively. The proposed liquid-filling MOF will be developed as thermo-optic sensor, attenuator or optical switch with the advantages of simple structure, compact configuration and easy fabrication.