• Food Science and Preservation
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• v.23 no.3
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• pp.422-431
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• 2016

To investigate the causes of the thermal deformations of packaging materials when microwave-heating ready-to-eat sauce products packaged in stand-up pouches, patterns of temperature changes were determined using an infra-red thermal imaging camera, a thermo-sensitive tape, and a fiver-optic thermometer. The temperature distributions of spicy chicken sauce and Indian curry samples in a stand-up pouch were found to be uneven during micrewave heating. A sharp increase in the temperature was detected, especially above the filling layers and in the corners of sealing layers of the package. The temperature measurements using an infra-red thermal imaging camera are restricted to the surface, and therefore might underestimate the actual temperature. Using a thermo-sensitive tape, temperature up to $200^{\circ}C$ were measured in the spicy chicken sauce sample showing package deformation. When the temperature is measured using a fiber-optic thermometer, it is crucial to have precise sensor performance to accurately measure the temperature in a narrow hot-spot area of the package. In this experiment, the fiber-optic thermometer was attached to a GaAs crystal sensor, which obtained more sensitive and accurate temperature measurements than those by a convectional sensor.

• Composites Research
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• v.18 no.5
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• pp.1-8
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• 2005

Among many fabrication methods of composite materials, filament winding is the most effective method for fabricating axis-symmetric structures such as pressure tanks and pipes. Filament wound pressure tanks are under high internal pressure during the operation and it has the complexity in damage mechanisms and failure modes. For this reason, it is necessary to monitor the tank through its operation as well as whole fabrication process. A large number of sensors must be embedded into multi points of the tank from its fabrication step for monitoring the whole tank. Fiber optic sensors, especially fiber Bragg grating(FBG) sensors are widely used for various applications because of good multiplexing capabilities. However, we need to develop the embedding technique of FBG sensors into harsh inner environment of the tank far the successful embedment. In this paper, we studied the embedding technique of a number of FBG sensors into filament wound pressure tanks considering multiplexing.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.5
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• pp.542-548
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• 2001

A robust, accurate, broad-band, alternating current sensor using fiber-optics is being developed as a part of optical over current protection relay system. The sensor uses the Faraday effect in optical fiber and polarimetric measurements tc sense electrical current. The current sensing coil consists of a length of twisted optical fiber and Faraday rotator mirror to suppress the linear birefringence effect. Due to its single-ended closed path structure, it can not only be easily installed to the target with great isolation from other fields in the vicinity, but the sensitivity can be increased by using multiple turns. This paper reports on the theoretical backgrounds of the sensor design and the preliminary experimental results.

• Journal of Sensor Science and Technology
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• v.9 no.5
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• pp.365-372
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• 2000

In this study, a multichannel taste sensor using the evanescent field absorption in fiber optic was developed, and evaluated its characteristics for several basic taste substances. This sensor is based on the change of evanescent field absorption at the surface of optical fiber core layer. The sensor device was made of a plastic-clad-silica fiber (3M Co., FP-400-UHT, core diameter $400\;{\mu}m$) and a middle portion of cladding layer was removed and the surface of stripped fiber core was dip-coated with a sensing membrane. And then, it was determined the difference of evanescent field absorption into the sensing membrane, according to various taste substances and its concentrations variance. The sensing membranes were prepared with six kinds of dyes, were known as potential sensitive dye together with silicone polymer the same refractive index of cladding. Each output patterns were obtained from the sensor devices could be distinguished not only five kinds of basic taste substances such as sweetness, saltiness, sourness, bitterness and umami, but also various mixed taste substances.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6A
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• pp.399-408
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• 2011

Development of smart sensors for structural health monitoring and damage detection has been advanced remarkably in recent years. Nowadays fiber optic sensors, especially fiber Bragg grating (FBG) sensors, have attracted many researchers' interests for their attractive features, such as multiplexing capability, durability, lightweight, electromagnetic interference immunity. In this paper, a damage detection approach of jacket-type offshore structures by principal component analysis (PCA) technique using FBG sensors are presented. An experimental study for a tidal current power plant structure as one of the jacket-type offshore structures was conducted to investigate the feasibility of the proposed method for damage monitoring. It has been found that the PCA technique can efficiently eliminate environmental effects from measured data by FBG sensors, resulting more damage-sensitive features under various environmental variations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.271-274
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• 2002

In this study, we fabricated the semiconductor laser for optical sensor with 1.55${\mu}{\textrm}{m}$wavelength region. In order to suppress lasing oscillation and to reduce the reflectivity, the devices of bending type were designed and fabricated. Their output power were 1.6㎽ at a pulse drive current of 100㎃. When the fabricated device was applied to optical fiber gyroscope, the output power of optical fiber was 540㎻ at a CW drive current of 100㎃, the full width at half maximum spectral width was 53nm. And the random-walk coefficient was measured to be 2.5$\times$10­$^3$deg/√hr, the gyro output drift was also found to be 0.3 deg/hr. So we confirmed the possibility of application to use for light source of optical fiber gyroscope.

• Journal of radiological science and technology
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• v.28 no.1
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• pp.9-12
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• 2005

In this study, film type radiation sensor tips are fabricated for remote sensing of X or g-ray with inorganic scintillators and plastic optical fiber. The visible range of light from the inorganic scintillator that is generated by X and g-ray is guided by the plastic optical fiber and is measured by optical detector and power-meter. It is expected that the fiber-optic radiation sensor which is possible to be developed based on this study is used for remote, fast and exact sensing of X or g-ray because of its characteristics such as very small size, light weight and no interference to electromagnetic fields.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.3
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• pp.211-216
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• 2016

In several industrial fields, epoxy resin is widely used as an adhesive for co-curing and manufacturing various structures. Controlling the manufacturing process is required for ensuring robust bonding performance and the stability of the structures. A fiber optic sensor is suitable for the cure monitoring of epoxy resin owing to the thready shape of the sensor. In this paper, a fiber Bragg grating (FBG) sensor was applied for the cure monitoring of epoxy resin. Based on the experimental results, it was demonstrated that the FBG sensor can monitor the status of epoxy resin curing by measuring the strain caused by volume shrinkage and considering the compensation of temperature. In addition, two types of epoxy resin were used for the cure-monitoring; moreover, when compared to each other, it was found that the two types of epoxy had different cure-processes in terms of the change of strain during the curing. Therefore, the study proved that the FBG sensor is very profitable for the cure-monitoring of epoxy resin.

• Korean Journal of Optics and Photonics
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• v.33 no.5
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• pp.210-217
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• 2022

In this paper, a study is conducted on the acceptable tolerance of an alignment device to reduce the optical loss caused by the alignment tolerance of a window hermetic optical connector. To increase the transmission distance of optical signals and fiber-optic communication systems, it is necessary to maintain and improve the high optical efficiency of the connectors used to bond optical fibers. In the case of the window hermetic optical connector, the optical system is aligned through an alignment device. At this time, since the two connectors are used together, each component is fixed, and further alignment is impossible. The alignment tolerance of the housing system and pin used to align the optical system of the connector causes optical loss, leading to serious problems in the fiber-optic communication system. Thus, to find the acceptable tolerance required for manufacturing the optical-connector alignment device, tolerance analysis is performed on the components of the optical connector, such as the ball lens and the window. We also implement single-mode and multimode optical-connector systems, respectively. Based on the results, we determine an acceptable tolerance value for the alignment device.

• Journal of Korean Neurosurgical Society
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• v.47 no.5
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• pp.365-369
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• 2010

Objective : There has been inconsistency about definition of the temporal stem despite of several descriptions demonstrating its microanatomy using fiber dissection and/or diffusion tensor tractography. This study was designed to clarify three dimensional configurations of the temporal stem. Methods : The fronto-temporal regions of several formalin-fixed human cerebral hemispheres were dissected under an operating microscope using the fiber dissection technique. The consecutive coronal cuts of the dissected specimens were made to define the relationships of white matter tracts comprising the temporal stem and the subcortical gray matters (thalamus, caudate nucleus, amygdala) with inferior limiting (circular) sulcus of insula. Results : The inferior limiting sulcus of insula, limen insulae, medial sylvian groove, and caudate nucleus/amygdala were more appropriate anatomical structures than the roof/dorso-lateral wall of the temporal horn and lateral geniculate body which were used to describe previously for delineating the temporal stem. The particular space located inside the line connecting the inferior limiting sulcus of insula, limen insulae, medial sylvian groove/amygdala, and tail of caudate nucleus could be documented. This space included the extreme capsule, uncinate fasciculus, inferior occipito-frontal fasciculus, anterior commissure, ansa peduncularis, and inferior thalamic peduncle including optic radiations, whereas the stria terminalis, cingulum, fimbria, and inferior longitudinal fiber of the temporal lobe were not passing through this space. Also, this continued posteriorly along the caudate nucleus and limiting sulcus of the insula. Conclusion : The temporal stem is white matter fibers passing through a particular space of the temporal lobe located inside the line connecting the inferior limiting sulcus of insula, limen insulae, medial sylvian groove/amygdala, and tail of caudate nucleus. The three dimensional configurations of the temporal stem are expected to give the very useful anatomical and surgical insights in the temporal lobe.