• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.11 s.116
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• pp.1172-1178
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• 2006

Measurement of blade strain with sensors directly installed on the blade has one critical issue, how to send the sensor signal to the ground. Strain-gauges have been dominantly used to directly measure stress of a blade and either a slip ring or a telemetry system has to be used to send measured signal to the ground. However, both systems have many inherent problems and sometimes very severe limitations to be practically used. In this paper, new on-line strain monitoring method using. FBG(Fiber Bragg Grating) sensors and a beam coupler is introduced. Measurement of rotor stress using FBG sensors is nothing new, but unlike other system which installs all necessary instruments on the rotor and use telemetry system to send data to the ground, this system makes use of light's unique characteristic - light travels through space. In this new approach, single optical fiber with many FBG sensors is installed on the blade and all other necessary instruments can be installed at ground thereby giving tremendous advantages over slip ring or telemetry system. A reference sensor is also introduced to compensate the beam coupler's transmission loss change due to rotation. The suggested system's good performance is demonstrated with experiments.

• Journal of Biosystems Engineering
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• v.35 no.2
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• pp.132-137
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• 2010

Site-specific N application for corn is one of the precision crop management. To implement the site-specific N application, various nitrogen stress sensing methods, including aerial image, tissue analysis, soil sampling analysis, and SPAD meter readings, have been used. Use of side-dressing, an efficient nitrogen application method than a uniform application in either late fall or early spring, relies mainly on the capability of nitrogen deficiency detection. This paper presents map-based variable rate nitrogen application based using a multi-spectral corn nitrogen deficiency(CND) sensor. This sensor assess the nitrogen stress by means of the estimated SPAD reading calculated from the corn leave reflectance. The estimated SPAD value from the CND sensor system and location information form DGPS of each field block was combined into the field map using a ArcView program. Then this map was converted into a raster file for a map-based variable rate application software. The relative SPAD (RSPAD = SPAD over reference SPAD) was investigated 2 weeks after the treatments. The results showed that the map-based variable rate application system was feasible.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.9 no.1
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• pp.11-16
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• 1998

Background and Objectives : Electrolarynx has been used as one of the methods of rehabilitation for the laryngectomees. Previous electrolarynx could not alter frequency and intensity simultaneously. This institute developed an electrolarynx named "Evada" using FSR(force sensing resistor) sensor, which can control the frequency(and/or intensity) simultaneously. This study was performed for the normal control and laryngectomees with three types of electrolarynx (Evada, Servox-inton, Nu-vois) to reveal functional characteristics of Evada Materials and Methods : five laryngectomees and five normal adults were made to express there sentences(discriptive sentence, "You stay here" ; question sentence, "You stay here？" ; exclamation sentence, "You!! stay here!"), using three types of electrolarynx. Frequency change and intensity change from first and last vowel was calculated in three sentences and analyzed statistically by paired T-test. Results : The frequency change in the question sentence and exclamation sentence was more prominent in Evada than in Servox-inton and Nu-vois. The intensity change in the question sentence and exclamation sentence was also more prominent in Evada than in Servox-inton and Nu-vois. Conclusions : Evada could control frequency and intensity simultaneously and control degree of frequency(and/or intensity) according to the pressing force into the button. Evada could adjust continuously frequency and intensity during conversation. So, Evada is better in producing intonation and contrastive stress than Nu-vois and Servox-inton.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2692-2695
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• 2008

Polydiacetylene (PDA) is chemosensor materials that exhibit non-fluorescent-to-fluorescent transition as well as blue-to-red visible color change upon chemical or thermal stress. They have been studied in forms of film or microarray chip, so far. In this paper, we provide a novel technique to fabricate continuous micro-fiber PDA sensor using in-situ laser-polymerization technique and 3-D hydrodynamic focusing on a microfluidic chip. The flow of a monomer solution with diacetylene (DA) monomer is focused by a sheath flow on a 3-D microfluidic chip. The focused flow is exposed to 365 nm UV laser beam for in-situ polymerization which generates a continuous fiber containing DA monomers. Then, the fiber is exposed to 254 nm UV light to polymerize DA monomers to PDA. Preliminary results indicate that the fiber size can be controlled by the flow rates of the monomer solution and sheath flows and that a PDA sensor fiber successively responds to chemical and thermal stress.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4021-4030
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• 2015

Pulse wave is the physiological responses through the autonomic nervous system such as ECG. It is relatively convenient because it can measure the signal just by applying a sensor on a finger. So, it can be usefully employed in the field of U-Healthcare. The objects of this study are acquiring the PPG (Photoplethysmography) one of the way of measuring the pulse waves in non-invasive way using the CMOS image sensor on a smartphone camera, developing the portable system judging stressful or not, and confirming the applicability in the field of u-Healthcare. PPG was acquired by using image data from smartphone camera without separate sensors and analyzed. Also, with that image signal data, HRV (Heart Rate Variability) and stress index were offered users by just using smartphone without separate host equipment. In addition, the reliability and accuracy of acquired data were improved by developing additional hardware device. From these experiments, we can confirm that measuring heart rate through the PPG, and the stress index for analysis the stress degree using the image of a smartphone camera are possible. In this study, we used a smartphone camera, not commercialized product or standardized sensor, so it has low resolution than those of using commercialized external sensor. However, despite this disadvantage, it can be usefully employed as the u-Healthcare device because it can obtain the promising data by developing additional external device for improvement reliability of result and optimization algorithm.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.263-266
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• 2004

This paper describes an intelligent piezoelectric traffic sensor which can be detected the over-weighted vehicles In motion. Based on finite element analysis for the sensor, the sensitivity was analyzed and the design was optimized. Studied parameters are the material properties of constitutional parts, the geometry of the sensor, the weight of the vehicle, and the speed of the vehicle. To verify the simulated results, we manufactured the sensor having the optimized geometry and the sensitivity was measured in the range from 0.5 to 3 ton of tensile and compressive stress. The measured results shows that the sensitivity and linearity of the sensor are closely agree with the designed values.

• Journal of Aerospace System Engineering
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• v.10 no.1
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• pp.82-85
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• 2016

In this study, structural design of exhaust gas sensor of automobile was performed. In order to evaluate the structural design of the measurement sensor, the structural analysis was performed by the finite element method. The vibration and thermal stress analysis was carried out at the high temperature condition. Finally, the structural test of sensor system was performed, and used for comparison with the analyzed model. Through the structural analysis and test, it is confirmed that the designed measurement sensor structure is acceptable.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.554-558
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• 2002

A magnetostrictive sensor is used to measure stress waves propagating in a ferromagnetic cylinder without physical contact. The performance of a magnetostrictive sensor is affected most significantly by the bias magnetic field applied around the measurement location. The goal of this paper is to carry out the topology optimization of the bias magnet and yoke assembly to maximize the sensor output for traveling bending waves. We will use the multi-resolution topology optimization strategy to find the assembly of the bias magnet and the yoke that is easy to realize. The effectiveness of the present design is confirmed by an actual measurement of the sensor signal with the proposed bias magnet and yoke configuration.

• Journal of Biosystems Engineering
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• v.22 no.1
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• pp.49-58
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• 1997

Finding of internal quality is crucial for getting under control quality of watermelon after harvest. A maturity sensing device of watermelon using repulsion characteristics was developed and evaluated. In this study, five different sensing probes were used to detect the physical changes after impact on watermelons. Total 15 watermelons were tested and evaluated into two classes: ripe and unripe. It was difficult to detect the overripe watermelons using the proposed sensor. Therefore, the results showed that the developed sensor could be used to separate unripe watermelons after harvest. The results from this study are summarized as follows. 1. It was successful to distinguish between the ripe and unripe watermelon by sensing the elastic characteristics on impact. 2. The hemisphere was best for the shape of sensing part because the hemisphere concentrate stress in impact part. 3. Among the five type developed sensor, the 1, 2, 3. 5-type sensor showed good character in distinguishing between ripe and unripe watermelon.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1392-1397
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• 2010

Currently in increasing number of urban tunnels with small overburden are excavated according to the principle of the New Austrian Tunneling Method(NATM). Successful design, construction and maintenance of NATM tunnel demands prediction, control and monitoring of ground displacement and support stress high accuracy. A magnetic anisotropy sensor is used for non-destructive measurement of stress on surfaces of a ferromagnetic material, such as steel. The sensor is built on the principle of the magneto-strictive effect in which changes in magnetic permeability due to deformation of a ferromagnetic material is measured in a non-destructive manner, which then can be translated into the absolute values of stresses existing on the surface of the material. This technique was applied to measure stresses of H-beams, used as tunnel support structures, to confirm expected measurement accuracy with reading error of about 10 to 20MPa, which was confirmed by monitoring strains released during cutting tests The results show that this method could be one of the promising technologies for non-destructive stress measurement for safe construction and maintenance of underground rock structures encountered in civil and mining engineering.