• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.103-106
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• 2004

Impact location monitoring is one of the major concerns of the smart health monitoring. For this application, multipoint ultrasonic sensors are to be employed. In this study, a multiplexed FBG sensor system with wide dynamic range was proposed and stabilization controlling system was also developed for the maintenance of maximum sensitivity of sensors. For the intensity demodulation system of FBG sensors, Fabry-Perot tunable filter(FP-TF) with 23.8nm FSR(free spectral range) was used, which behaves as two separate filters between $1530 \~ 1560$ nm range. Two FBG sensors were attached on the bottom side of the graphite/epoxy composite beam specimen, and low velocity impact tests were performed to detect the one-dimensional impact locations. Impact locations were calculated by the arrival time differences of the impact longitudinal waves acquired by the two FBGs. As a result, multiplexed in-line FBG sensors could detect the moment of impact precisely and found the impact locations with the average error of 1.32mm.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.542-544
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• 2005

This paper describes the detection of spatio-temporal parameter using an accelerometer and footswitches to evaluate a symmetry and balance of hemiplegic patients. We detected gait data using a 3-axis accelerometer that mounted between L3 and IA intervertebral area and footswitches made by FSR-Sensor attached insole. To minimize the error of the gait parameters to be detected incorrectly in case of using only accelerometer, we enhancement the performance of detection by measuring an accelerometer and foots witches data at the same time. So, it was possible to detect more accurate gait parameters. As a result, we can confirm the symmetry and balance of hemiplegic patients. In the future. these results could be used to evaluate the walking ability in hemiplegic patients in clinical pratice.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.869-870
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• 2006

In this study, we proposed an algorithm which can detect the walking event in hemiplegic patient using three axis acceleration signal. Twenty hemiplegic patients were participated in an experiment on a level corridor. To evaluate the accuracy, we compared the time difference between the detected event and signal from FSR-Sensor. Consequently, the mean difference of 46.1ms was obtained and it suggests that the proposed method is effective to detect the walking event in hemiplegic patient. In future, these results could be used to evaluate the walking ability in hemiplegic patient in clinical practice.

• Korean Journal of Optics and Photonics
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• v.19 no.2
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• pp.127-131
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• 2008

A refractometric glucose biosensor incorporating a vertically coupled microring resonator in polymers was proposed and realized. The ring was covered with a target analyte of glucose solution with a certain concentration, so that its effective refractive index could be altered and, as a result, the resonance wavelength of the sensor was shifted. Therefore the concentration of the glucose solution can be estimated by observing the shift in the resonance wavelength. Two schemes were exploited for enhancing the sensitivity of the sensor. First, the effective refractive index of the polymeric waveguide used for the resonator sensor was adjusted to approach that of the target analyte as best as possible. Second, the ring waveguide, which serves as a crucial sensing part, was appropriately over-etched to enlarge its contact area with the analyte. The proposed resonator sensor was designed with the beam propagation method. The refractive indices of the core and cladding polymer involved were 1.430 and 1.375 respectively, leading to the waveguide's effective refractive index of ${\sim}1.390$, which is faiirly close to that of the glucose solution of ${\sim}1.333$. The prepared ring resonator with the $400-{\mu}m$ radius exhibited the free spectral range of 0.66 nm, the bandwidth of 0.15 nm, and the quality factor of 10,000. For the sensor operating at 1,550 nm wavelength, the achieved sensitivity was as great as 0.28 pm/(mg/dL), which is equivalent to 200 nm/RIU.

• Journal of Korea Multimedia Society
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• v.23 no.2
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• pp.282-292
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• 2020

In order to minimize casualties from marine vessel accidents that occur frequently at home and abroad, it is important to ensure the safety of the passengers aboard the vessel in the event of an accident. There is an EPIRB system as a system for disaster preparedness in the marine situation currently on the market, but there is a problem that the price is very expensive. In order to overcome the cost problem, which is a disadvantage of previous system, LoRaWAN-based communication is used. LoRaWAN communication-based vessel positioning and risk detection system based on LoRaWAN communication transmits measurement data of each module using two Beacon and GPS modules to stably perform position measurement for both indoor and outdoor situations. The rider danger situation detection system can detect the safety status of the rider using the 3-axis acceleration sensor, collect data from the rider positioning system and the rider safety status detection system, and send to server using LoRa communication. When conducting communication experiments in the long-distance maritime situation and actual communication experiments using the implemented system, it was found that the two experiments showed over 90% communication success rate on average.

• International Journal of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.11-17
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• 2019

Plantar pressure data can be used not only for walking patterns in daily life, but also for eating, health care, and disease prevention. For this reason, the importance of plantar pressure measurement has recently increased. However, most systems that can measure both static and dynamic plantar pressure at the same time are expensive, not portable, and not universal. In this study, we propose a system that effectively reduces the number of sensors in plantar pressure system. Through this, we want to increase the economics and practicality by reducing the size and weight of the system, as well as the power consumption. First, for static plantar pressure and dynamic plantar pressure, the values measured by existing precision instruments are analyzed to determine how many measurement parts the insole is divided into. Next, for the divided measuring parts, the position of the sensor is determined by calculating the Center of Pressure (COP) for each part with the values of all dynamic and static plantar pressure sensors. Finally, in order to construct a personalized plantar pressure measurement system, we propose a weighting method for the static plantar pressure COP and the dynamic plantar pressure COP for each part.

• The Journal of Korea Robotics Society
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• v.18 no.1
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• pp.18-28
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• 2023

This study introduces a smart wrist band system with pressure measurements using wrist skin curvature variation due to finger motion. It is easy to wear and take off without pre-adaptation or surgery to use. By analyzing the depth variation of wrist skin curvature during each finger motion, we elaborated the most suitable location of each Force Sensitive Resistor (FSR) to be attached in the wristband with anatomical consideration. A 3D depth camera was used to investigate distinctive wrist locations, responsible for the anatomically de-coupled thumb, index, and middle finger, where the variations of wrist skin curvature appear independently. Then sensors within the wristband were attached correspondingly to measure the pressure change of those points and eventually the finger motion. The smart wrist band was validated for its practicality through two demonstrative applications, i.e., one for a real-time control of prosthetic robot hands and the other for natural human-computer interfacing. And hopefully other futuristic human-related applications would be benefited from the proposed smart wrist band system.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.2
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• pp.379-386
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• 2023

When patients suffer from finger injuries, their finger joints can become stiff and inflexible due to decreased ability to exercise the finger tendons. This can lead to a loss of strength and difficulty using their hands. To address this, it is important to provide patients with consistent rehabilitation treatment that can help restore finger flexibility and strength simultaneously. In this study, we propose wearable gloves that use FSRs (force sensitive resistors) for finger strength training. The glove is designed to be adjustable using rubber bands and a custom PCB is designed for signal acquisition. For the evaluation of finger strength training, the result was analyzed in four cases. We suggest a vector that represents the center of five finger forces, and the result shows that the vector can indicate the level of force balance.