• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.3
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• pp.14-21
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• 2010

For the ubiquitous healthcare environment, real-time measurement of biomedical signals and accuracy of the measured biomedical information are very important. In addition, it is important to develop a healthcare device with low power In this paper, the synchronized pulse in a heartbeat was detected from the radial artery using the piezo film sensor, in order to eliminate inconvenience to wear a pulse detection finger probe. We can get a best output after applying the adaptive noise canceller using two piezo film sensor signals, pulse signal having motion artifacts and motion artifacts reference signal. To detect heartbeat, we use maximum point detection method from pulse removed motion artifacts.

• Journal of Sensor Science and Technology
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• v.4 no.2
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• pp.22-28
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• 1995

A Michelson interferometric AC current sensor has been fabricated by using a single mode optical fiber and a cylindrical PZT tube of which a radial dimension varies with applied voltage. The signal processing scheme used in this work, measures the magnitude of AC current regardless of the frequency of the current. An AC current is measured by counting the number of interference fringe during half cycle of the AC current. The number of interference fringes varies linearly with the magnitude of the current and the error range is within 5% at the temperature range from $-20^{\circ}C$ to $80^{\circ}C$.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.6
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• pp.483-489
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• 2016

The typical methods used for inspecting ferromagnetic pipes include the ultrasonic testing (UT) contact method and the following non-contact methods: magnetic flux leakage (MFL), electromagnetic acoustic transducers (EMAT), and remote field eddy current testing (RFECT). Among these methods, the RFECT method has the advantage of being able to establish a system smaller than the diameter of a pipe. However, the method has several disadvantages as well, including different sensitivities and difficult-to-repair coil sensors which comprise its array system. Therefore, a giant magneto-resistance (GMR) sensor was applied to address these issues. The GMR sensor is small, easy to replace, and has uniform sensitivity. In this experiment, the GMR sensor was used to measure remote field and defect signal characteristics (in the axial and radial directions) in a ferromagnetic pipe. These characteristics were measured in an effort to investigate standard defects at changing depths within a pipe. The results show that the experiment successfully demonstrated the applicability of the GMR sensor to RFECT signal detection in ferromagnetic pipe.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.227-236
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• 2002

We have performed two kinds of experimental modal analyses fur a radial tire for passenger car under free-suspension. One is the modal analysis to obtain three-dimensional modes of tire using accelerometers and the other is the one to identify cavity resonance frequency using a pressure sensor. From the first analysis, we have obtained the three-dimensional natural modes, which makes it possible to grasp the features of the modes and to classify the vibrational modes into symmetric, non-symmetric, and antisymmetric modes in a simple way by using the experimental results. From the first and the second experimental analyses we have identified the cavity resonance frequency and its three-dimensional mode shape.

• Journal of Sensor Science and Technology
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• v.25 no.2
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• pp.138-142
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• 2016

A pulse measurement by tonometry provides useful information for diagnosis, including not only blood pressure and heart rate but also parameters for estimating a condition of the cardiovascular system. Currently, various pulse measurement devices based on the tonometry have been developed. A reliability of these devices is determined by a positioning technic between the sensor and the blood vessel and a controlling technique of the pressurization level. An angle of the sensor for the pulse measurement seems to be highly related with a measured signal, however, the objective studies for this issue have been not published. In this paper, the variation of the pulse signals by tonometry direction was experimentally assessed according to the angle of the sensor. In order for guaranteeing the repeatability of the experiment, we used a pulse generator device, which can generate human pulse signal by using silicon tube and fluid pump, and developed a structure for precise adjustment of the angle and the pressurization level of the sensor. The angle of the sensor was acquired by an inclinometer, which was attached at the opposite side of the sensor. As results, a coefficient of variation (CV) of a maximum amplitude (MA) of the pulse wave was largely increased over the angle range of $-9{\sim}9^{\circ}$. Furthermore, the changes of the pulse shape showed different aspects according to the sign of the angle tilted along the blood vessel. It is expected that the results of this study can be helpful for developing more precise pulse measurement devices based on the tonometry and applying in clinic.

• Structural Monitoring and Maintenance
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• v.3 no.4
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• pp.377-393
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• 2016

The present work develops an expert system for detecting and predicting the crude oil types and properties at normal temperature ${\theta}=25^{\circ}C$, by evaluating the dielectric properties of the fluid transfused inside glass fiber reinforced epoxy (GFRE) composite pipelines, by using electrical capacitance sensor (ECS) technique, then used the data measurements from ECS to predict the types of the other crude oil transfused inside the pipeline, by designing an efficient artificial neural network (ANN) architecture. The variation in the dielectric signatures are employed to design an electrical capacitance sensor (ECS) with high sensitivity to detect such problem. ECS consists of 12 electrodes mounted on the outer surface of the pipe. A finite element (FE) simulation model is developed to measure the capacitance values and node potential distribution of ECS electrodes by ANSYS and MATLAB, which are combined to simulate sensor characteristic. Radial Basis neural network (RBNN), structure is applied, trained and tested to predict the finite element (FE) results of crude oil types transfused inside (GFRE) pipe under room temperature using MATLAB neural network toolbox. The FE results are in excellent agreement with an RBNN results, thus validating the accuracy and reliability of the proposed technique.

• Journal of ILASS-Korea
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• v.5 no.1
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• pp.49-57
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• 2000

This study presents the flow visualization results, velocity and turbulence intensity measurements made within an air filter cover and entry region of a mass air flow sensor (MAFS) which is used in an induction system of 3.8L engine. Flow structure in two air filter cover assemblies were examined. The first was a clear plastic replica of the production cover while the second was a modified clear plastic cover with a geometry configured to reduce fluctuations. High speed flow visualization and laser doppler velocimetry (LDV) systems were used to reveal and analyze the flow field characteristics encountered in the sensor design process under steady flow conditions. A 40-watt copper vapor laser was used as a light source. Its beam is focused down to a sheet of light approximately 1.5mm thick. The light scattered off the particles was recorded by a 16mm high speed rotating prism camera at 5000 frames per second. A comparison of the flow patterns and LDV measurements in the original and modified air filter covers is presented to illustrate the controlling effect of the cover design on the turbulence structure formation near the bypass and on the sensor output signal. In both axial and radial planes of the main passage it was found that the turbulence flow pattern is remarkably influenced by the air filter cover and main passage configuration.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.285-286
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• 2006

The essential tasks to operate the welding robot are the acquisition of the position and/or shape of the parent metal. For the seam tracking or the robot automation, many kinds of contact and non-contact sensors are used. Recently, the vision sensor is most popular. In this paper, the development of the system which measures the profile of the welding part is described. The total system will be assembled into a compact module which can be attached to the head of welding robot system. This system uses the line-type structured laser diode and the vision sensor It implemented Direct Linear Transformation (DLT) for the camera calibration as well as radial distortion correction. The three dimensional shape of the parent metal is obtained after simple linear transformation and therefore, the system operates in real time. Some experiments are carried out to evaluate the performance of the developed system.

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.5
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• pp.149-154
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• 2009

By increasing people's average life span, interest for health is highly growing. According to hoping to check their body condition, people have a medical checkup periodically to check their condition. But, they can prevent disease or are able to make a health care through checking people's pulse or blood pressure. In this paper, two different pulse measurement systems were developed, one system using a photosensor which is able to measure transmissivity's change through blood volume and another system using a piezo-electric sensor which can measure pulse when it measures radial artery's pressure in the wrist are realized. We compared two systems each other.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.333-337
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• 1996

The spindle directly affects parts accuracy during machining, or work piece in machine tools. In this paper a comprehensive study is performed combined mr performance of machine tool spindle. The developed methology has been practically applied to a spindle of machine tools.