• Proceedings of the KOSOMBE Conference
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• v.1990 no.11
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• pp.71-74
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• 1990

• Journal of Sensor Science and Technology
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• v.17 no.6
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• pp.462-469
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• 2008

In this study, we have fabricated a fiber-optic radiation sensor using an organic scintillator and plastic optical fiber for brachytherapy dosimetry. Also, we have measured relative depth dose rates of Ir-192 source using a fiber-optic sensor and compared them with the results obtained using a conventional EBT film. Cerenkov lights which can be a noise in measuring scintillating light with a fiber-optic sensor are measured and eliminated by using of a background optical fiber. It is expected that a fiber-optic radiation sensor can be used in brachytherapy dosimetry due to its advantages such as a low cost, simple usage and a small volume.

• Journal of Sensor Science and Technology
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• v.18 no.5
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• pp.365-371
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• 2009

In this study, we have fabricated a fiber-optic pH sensor which is composed of a light source, plastic optical fibers and a spectrometer. As an indicator, a phenol red is used, and a pH liquid solution is prepared by mixing of phenol red and various kinds of pH buffer solutions in these experiments. The emitting light from a light source is guided by plastic optical fibers to the pH liquid solution, and the optical characteristic of a light is changed in the pH liquid solution according to its color change. Therefore, we have measured the intensities and wavelength shifts of the modulated lights, which are changed due to the color variations of phenol red at different pH values, by using of a spectrometer for spectral analysis. Also, the relationships between the pH values of liquid solutions and the optical properties of modulated light according to the change of color of phenol red are obtained.

• Journal of Sensor Science and Technology
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• v.21 no.4
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• pp.287-292
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• 2012

A fiber-optic radiation sensor was fabricated using a sensing probe, a plastic optical fiber, a photomultiplier tube, and a multichannel analyzer for gamma-ray spectroscopy. As an inorganic scintillator of the sensing probe, a LYSO crystal was used. In this study, we obtained the relationship between the photon counts of the fiber-optic radiation sensor and the activity of the radioactive isotope. In addition, the gamma-ray energy spectra were also measured using a fiber-optic radiation sensor to discriminate species of gamma-ray emitters.

• Korean Journal of Optics and Photonics
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• v.18 no.4
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• pp.241-245
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• 2007

In this study, a two-dimensional fiber-optic radiation sensor has been developed using water-equivalent organic scintillators for photon beam therapy dosimetry. Two-dimensional photon beam distributions and percent depth doses(PDD) are measured according to the energies and field sizes of the photon beam. This sensor has many advantages such as high resolution, real-time measurement and ease of calibration over conventional radiation measurement devices.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.1
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• pp.9-13
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• 2011

The purpose of this study was to investigate the effects of the secondary tasks such as sending text message (STM) and searching navigation (SN) on skin conductance level (SCL) and deviation of vehicle speed during driving. The participants included 30 healthy adults; 14 males aged $25.2{\pm}0.9$ with $1.9{\pm}1.8$ years of driving experiences and 16 females aged $22.6{\pm}1.9$ with $1.2{\pm}0.8$ years of driving experiences. All subjects were instructed to keep a constant speed (80km/h or 100km/h). SCL and deviation of vehicle speed were measured during driving only and driving with secondary tasks. SCL and deviation of vehicle speed were more increased during the driving with secondary tasks than driving only. Secondary tasks increased an activation of sympathetic nerve system and decreased driving performance. However, there were no significant differences in the SCL and deviation of vehicle speed according to gender and speed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.2
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• pp.9-15
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• 2012

The purpose of this study was to investigate the effects of the secondary tasks such as sending text message (STM) and searching navigation (SN) on skin conductance level (SCL) and driving performance of relatively aged and high-experienced drivers. The subjects included 26 taxi drivers; 12 males aged $56.3{\pm}4.4$ with $28.4{\pm}6.4$ years of driving experiences and 14 females aged $55.5{\pm}3.5$ with $19.4{\pm}5.0$ years of driving experiences. All subjects were instructed to keep a constant following distance (30m) from the car ahead and a given vehicle speed (80km/h or 100km/h) in a driving simulator. The relative change of SCL, vehicle velocity deviations, and average following distances were measured during driving only and driving with secondary tasks. The relative change of SCL, average following distance, and vehicle velocity deviation were more increased during the driving with secondary tasks than driving only. The relative change of SCL, vehicle velocity deviation, and average following distance were more affected by driving with 100km/hr than 80km/hr of a given vehicle speed. Secondary tasks increased a work load of drivers in term of SCL change, and decreased driving performance in terms of the vehicle velocity deviation and average following distance.

• Proceedings of the KOSOMBE Conference
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• v.1990 no.11
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• pp.82-85
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• 1990

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.2
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• pp.18-22
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• 2010

The purpose of this study was to investigated correlation between personal aggression and skin conductance level during watching attack image. Twenty three male ($21.4\pm1.8$ years) college students participated in this experiment. A personal aggression of each subject measured by questionnaire. The experimental procedure consisted of four phases, i.e., rest state (15 min), control image 1 (2 min. 14 sec), aggression image (50 sec), and control image 2 (2 min. 14 sec). Control image 1 and 2 consisted of sea, mountain, and valley scenary. Aggression image used scenes of the violence movie. Skin Conductance Level (SCL) of electrothermal activity was measured during watching the images. The SCL was greater during aggression image than during control image 1 and 2. A negative correlation was found between aggressive personality and change rate of SCL during watching aggression image compared to control image 1. This results suggests that aggression image was accompanied by the higher activation of Sympathetic Nervous System (SNS). Also, the higher aggression scores, an increasing rate of SNS activation was become smaller during watching aggression image.

• Journal of Sensor Science and Technology
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• v.16 no.5
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• pp.331-336
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• 2007

In this study, we have fabricated an infrared optical fiber based sensor which can monitor the respiration of a patient. The design of a chalcogenide optical fiber based sensor is suitable for insertion into a high electro-magnetic field environment because the sensor consists of low cost and compact mid-infrared components such as an infrared light source, a chalcogenide optical fiber and a thermopile sensor. A fiber-optic respiration sensor is capable of detecting carbon dioxide ($CO_{2}$) in exhalation of a patient using the infrared absorption characteristics of carbon gases. The modulated infrared radiation due to the presence of carbon dioxide is guided to the thermopile sensor via a chalcogenide receiving fiber. It is expected that a mid-infrared fiber-optic respiration sensor which can be developed based on the results of this study would be highly suitable for respiration measurements of a patient during the procedure of an MRI.