• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.9
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• pp.659-668
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• 2008

Combustion instability has been considered as very important issue for developing gas turbine and rocket engine. There is a need for fundamental understanding of combustion instability. In this study, combustion instability was numerically and experimentally investigated in a dump combustor with bluff body. The fuel and air mixture had overall equivalence ratio of 0.9 and was injected toward dump combustor. The pressure oscillation with approximately 256Hz was experimentally obtained. For numerical simulation, the standard k-$\varepsilon$ model was used for turbulence and the hybrid combustion model (eddy dissipation model and kinetically controlled model) was applied. After calculating steady solution, unsteady calculation was performed with forcing small perturbation on initial that solution. Pressure amplitude and frequency measured by pressure sensor is nearly the same as those predicted by numerical simulation. Furthermore, it is clear that a combustion instability involving vortex shedding is affected by acoustic-vortex-combustion interaction. The phase difference between the pressure and velocity is $\pi$/2, and that between the pressure and heat release rate is in excitation range described by Rayleigh, which is obvious that combustion instability for the bluff body combustor meets thermoacoustic instability criterion.

• Composites Research
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• v.34 no.3
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• pp.161-166
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• 2021

In this study, we present a research method to develop a shoe that prevents foot injury by inducing the foot pressure. An orthogonal grid sensor was used to check the foot pressure in the upright standing position, and the change in the foot pressure distribution for various conditions was compared. We checked the conditions for distributing foot pressure efficiently by changing the spring constant of the spring inserted into the sole of the shoe and the foot pressure generated with or without the arch of the insole. In order to minimize the experimental error from the randomness of the human body's behavior, it is possible to predict through foot pressure under certain conditions through finite element analysis that simulates the pressure distribution. By checking the change of foot pressure according to the number and arrangement of springs through finite element analysis, conditions were established to provide more efficient foot pressure. The result can be used for designing footwear for patients with diabetic feet.

• Journal of Integrative Natural Science
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• v.9 no.3
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• pp.199-205
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• 2016

In this paper, we established ZIGBEE home network and combined smart-grid and u-Healthcare system. We assisted for amount of electricity management of household by interlocking home devices of wireless sensor, PLC modem, DCU and realized smart grid and u-Healthcare at the same time by verifying body heat, pulse, blood pressure change and proceeded living body signal by using SVM algorithm and variety of ZIGBEE network channel and enabled it to check real-time through IHD which is developed by user interface. In addition, we minimized the rate of energy consumption of each sensor node when living body signal is processed and realized Query Processor which is able to optimize accuracy and speed of query. We were able to check the result that is accuracy of classification 0.848 which is less accounting for average 17.9% of storage more than the real input data by using Mjoin, multiple query process and SVM algorithm.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.2
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• pp.80-85
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• 2020

Recently the incidence of musculoskeletal disorders in students and office workers is increasing, and the necessity of maintaining correct posture and corrective training is required, but related research is insufficient. In the previous study, a membrane sensor or a pressure sensor was placed on the seat cushion to see the deviation of the body weight, or a sensor that restrained the user was attached to measure the position change. In this study, a sensor device for detecting a position change in consideration of wearing comfort was developed, and the measured angle was verified through an analysis app. A sensor device consisting of an IMU sensor is attached to the cervical spine and vertebra spine to measure the position transformation in the sitting position. The change value of the position measured by the two sensors was converted into an angle, and the angle value is displayed in real time through the analysis app. In this study, the possibility of measuring the real-time change value according to the change in position, the convenience of wearing, and the tendency of angle measurement were proved. Future research should proceed with more precise angle calculation and correction of motion noise.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.7
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• pp.433-441
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• 2007

The bio-Sensors, which are sensing the vital signs of human bodies, are largely used by the medical equipment. Recently, the sensor network technology, which composes of the sensor interface for small-seize hardware, processor, the wireless communication module and battery in small sized hardware, has been extended to the area of bio-senor network systems due to the advances of the MEMS technology. In this paper we have suggested a design and implementation of a health care information system(called u-EMS) using a bio-sensor network technology that is a combination of the bio-sensor and the sensor network technology. In proposed system, we have used the following vital body sensors such as EKG sensor, the blood pressure sensor, the heart rate sensor, the pulse oximeter sensor and the glucose sensor. We have collected various vital sign data through the sensor network module and processed the data to implement a health care measurement system. Such measured data can be displayed by the wireless terminal(PDA, Cell phone) and the digital-frame display device. Finally, we have conducted a series of tests which considered both patient's vital sign and context-awared information in order to improve the effectiveness of the u-EMS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1389-1397
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• 2016

This study was to evaluate opportunities for the commercialization of smart insole. smart technology is evolving to Insole. Pressure-sensitive sensor or an acceleration sensor is applied to create a balance of the feet and body, is also evolving for entertainment (sports, entertainment, etc.) and health care. Moreover, smart insole can fix an incorrect walking habit by sending a weight value measured by the sensor on a smartphone and during the movement, smart insole helps to correct body balance by measuring the center of gravity moving condition. However, smart tendency of the insole has yet to create a clear boundary in the entertainment and healthcare markets. This is because the fitness band, smart socks, smart shoes can also replace the benefits of a smart insole. Interestingly, the business opportunities are appearing more frequently in health care solution service of electrocardiogram, body temperature, blood pressure, etc., rather than smart devices.

• Journal of Fashion Business
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• v.10 no.1
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• pp.31-40
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• 2006

We studied relation between the clothing pressure applied by types of brassiere, postures, feeling of tightness. The main results were summerized as follows; 1. The research subjects of this study were 9 who rate of body fat was borderline and degree of fatness was normal. As a result of clothing pressure, the most prefered value was $36.86g/cm^2$ on sensor 2 in standing position and the next was $34.76g/cm^2$ on sitting position. Furthermore, The maximum value of sensor 2 was $59.08g/cm^2$ (in standing), $57.93g/cm^2$ (in sitting). On the other hand, The average clothing pressure of bra C type was $23.67g/cm^2$ 2. The study of feeling of tightness applied by bra type was high in order of C

• Journal of Sensor Science and Technology
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• v.10 no.3
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• pp.148-155
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• 2001

A pressure sensor on the tip of a catheter which is utilized to measure the in-vivo pressure in a human body was fabricated and the characteristic of the pressure sensor as measured. To fit into a catheter with 1 mm caliber, samples of $150\;{\mu}m$(thickness) ${\times}$ (600, 700, 800, 900, 1000) ${\mu}m$(width) ${\times}2\;mm$(length) was fabricated. The thicker face with $450\;{\mu}m$ thickness of SDB wafer was made thin to $134\;{\mu}m$ thickness using KOH etchant and it made possible to fabricate sensor cell with the width shorter than 1 mm. Different to the whitstone bridge sensor, we formed one piezoresistor and one reference resistor in sensor. Therefore there are possibilities of reduction of the sensitivity, then by using the simulation tool ANSYS 5.5.1, the location and the type of the piezoresistor was optimized. Another piezoresistor type of sensor which contain one longitudinal and one transverse piezoresistor was fabricated at the same time, but the sensitivity was not improved very much. To get the output versus the pressure, a constant current source and a implementation amplifier was used. As a result, the maximum sensitivity of the sensor with one piezoresistor was $1.6\;{\mu}V/V/mmHg$.

• Journal of Advanced Navigation Technology
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• v.19 no.5
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• pp.446-451
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• 2015

Recently, researches on sensor-based U-health applications that provide personal health information such as blood pressure, body temperature, and glucose, have actively been studied. The health information obtained via sensors, however, may have accuracy problems so that they can not be used unprocessed. This paper proposes a sensor abstraction layer for enhancing the accuracy of sensor readings from biomedical sensors that interact with smart phones. This layer recognizes sensor types and converts sensor readings into a form as specified in ISO/IEEE 11073 Personal Health Standard. When necessary, not only a filtering method that eliminates outlier values from sensor readings but also a summarization method that transforms them into more suitable forms, can also be applied. An android-based development board is used for the evaluation of proposed sensor abstraction layer. The results obtained by applying filtering and summarization show improved accuracy over unprocessed sensor readings of the body temperature and heartbeat sensors.

• Journal of Auto-vehicle Safety Association
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• v.12 no.1
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• pp.52-61
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• 2020

In recent years, the increasing interest in health-care requires the industrial products to be well-designed ergonomically. In the commercial vehicle industry, several researchers have demonstrated the driver's posture has great effect on the orthopedic desease such as fatigue, back pain, scoliosis, and so on. However, the existing sensor systems developed for measuring the driver posture in real time have suffered from inaccuracy and low reliability issues. Here, we suggest our smart vehicle seat system capable of real-time driver posture monitoring by using the air bag sensor package with high sensitivity and reliability. The ergonomic numerical model which can evaluate a driver's posture has been developed on the basis of the human body segmentation method followed by simulation-based validation. Our experimental analysis of obtained pressure distribution of a vehicle seat under the different driver's postures revealed our smart vehicle system successfully achieved the driver's real-time posture data in great agreement with our numerical model.