• Science of Emotion and Sensibility
• /
• v.22 no.1
• /
• pp.89-100
• /
• 2019

Sleep apnea, a medical condition associated with a variety of complications, is generally monitored by standard sleep polysomnography, which is expensive and uncomfortable. To overcome these limitations, this study proposes an unconstrained wearable monitoring system with stretch-fiber sensors that integrate with the wearer's clothing. The system allows patients to undergo examinations in a familiar environment while minimizing the occurrence of skin allergies caused by adhesive tools. As smart clothing for adult males with sleep apnea, long-sleeved T-shirts embedding fibrous sensors were developed, enabling real-time monitoring of the patients' breathing rate, oxygen saturation, and airflow as sleep apnea diagnostic indicators. The gauge factor was measured as 20.3 in sample 4. The maximum breathing intake, measured during three large breaths, was 2048 ml. the oxygen saturation was measured before and during breath-holding. The oxygen saturation change was 69.45%, showing a minimum measurable oxygen saturation of 70%. After washing the garment, the gauge factor reduced only to 18.0, confirming the durability of the proposed system. The wearable sleep apnea monitoring smart clothes are readily available in the home and can measure three indicators of sleep apnea: respiration rate, breathing flow and oxygen saturation.

• Tunnel and Underground Space
• /
• v.33 no.5
• /
• pp.425-434
• /
• 2023

To measure the wear amount of the TBM disk cutter in real time, it is important not only to automate the measurement using sensors, but also to stably transmit the measured data to the information processing system. In this study, we investigated the viability of utilizing Bluetooth Low Energy (BLE) technology to wirelessly transmit sensor data from the TBM cutter head to a receiver located at the chamber's rear. Through laboratory experiments, we analyzed the Received Signal Strength Index (RSSI) of the receiver considering various signal strength of the transmitter, separation distances between the transmitter and receiver and chamber fill materials. Our results demonstrate that wireless data transmission is feasible across all tested conditions when the transmitter signal strength is 0 dBm or higher.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.45 no.5
• /
• pp.28-34
• /
• 2008

The real-time biomedical signal monitoring is a very important factor to realize the ubiquitous healthcare environment. Most of these devices for monitoring the biomedical information get the PPG signal from the user, and these signals are utilized for monitoring their health. It is inconvenient to get the PPG because the user should wear the finger probe with his finger for measuring the PPG signal. Also it is difficult to get the PPG correctly, because of the motion artifacts from the movement of the user. In this paper, we develop the watch type biomedical signal monitoring system without the finger probe, and propose the new algorithm for reducing the motion artifacts from the PPG signal. We designed the system which gets the PPG from the sensor on the wrist band strip. As compared with the finger probe type, this system we proposed is more affected by the motion artifacts. So to filter this motion artifacts, we propose the new method; the improved PMAF(Periodic Moving Average Filter) method.

• Fire Science and Engineering
• /
• v.26 no.1
• /
• pp.96-101
• /
• 2012

The buildings of domestic wear the upper floors and an underground in-depth reconciliation tendency to do and the possibility of fire occurrence at the time of formation accident is coming to be high. Therefore will be scattered to various place and is established and prevention of disaster information of the receiver which will integrate there is a necessity which will manage. In this paper away where each receiver is installed in the fire for the remote monitoring and controld able to connect to the Internet and fiber optic cable that can be networked fire receiver and control desk was constructed. Between each device can be used by the fire, and more depending on the status of monitoring and alarm, control and maintenance can be performed to develop an integrated management system. The system is evaluated by the criteria of the KFI, and for each segment of the signal propagation time to perform experiments confirmed the reliability of the performance.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.6
• /
• pp.600-606
• /
• 2012

Upon investigation of the damaged wheels for high speed train it was determined that the damage was caused by rolling contact fatigue during operation of train. The major problems that railway vehicle system using wheel-rail has to face during operation of railway vehicle are rolling contact fatigue, cracks in wheels, cracks in rails and wheel-rail profile wear. If these deficiencies are not controlled at early stages the huge economical problems due to unexpected maintenance cost in railway vehicle can be happened. Also, If the accurate knowledge of contact conditions between wheel and rail can be evaluated, the damage of wheel can be prevented and the maintenance operation can save money. This paper presents the applicability of electro-magnetic technique to the detection and sizing of defects in wheel. Under the condition of continuous rolling contact fatigue the damage of wheel has continuously monitored using the applied sensor. It was shown that the usefulness of the applied sensor was verified by twin disc test and the measured damaged sizes showed good agreement with the damaged sizes estimated by electro-magnetic technique.

• Structural Monitoring and Maintenance
• /
• v.6 no.4
• /
• pp.317-346
• /
• 2019

Performance assessment of pavements proves useful, in terms of handling the ride quality, controlling the travel time of vehicles and adequate maintenance of pavements. Roughness profiles provide a good measure of the deteriorating condition of the pavement. For the accurate estimates of pavement roughness from dynamic vehicle responses, vehicle parameters should be known accurately. Information on vehicle parameters is uncertain, due to the wear and tear over time. Hence, condition monitoring of pavement requires the identification of pavement roughness along with vehicle parameters. The present study proposes a scheme which estimates the roughness profile of the pavement with the use of accurate estimates of vehicle parameters computed in parallel. Pavement model used in this study is a two-layer Euler-Bernoulli beam resting on a nonlinear Pasternak foundation. The asphalt topping of the pavement in the top layer is modeled as viscoelastic, and the base course bottom layer is modeled as elastic. The viscoelastic response of the top layer is modeled with the help of the Burgers model. The vehicle model considered in this study is a half car model, fitted with accelerometers at specified points. The identification of the coupled system of vehicle-pavement interaction employs a coupled scheme of an unbiased minimum variance estimator and an optimization scheme. The partitioning of observed noisy quantities to be used in the two schemes is investigated in detail before the analysis. The unbiased minimum variance estimator (MVE) make use of a linear state-space formulation including roughness, to overcome the linearization difficulties as in conventional nonlinear filters. MVE gives estimates for the unknown input and fed into the optimization scheme to yield estimates of vehicle parameters. The issue of ill-posedness of the problem is dealt with by introducing a regularization equivalent term in the objective function, specifically where a large number of parameters are to be estimated. Effect of different objective functions is also studied. The outcome of this research is an overall measure of pavement condition.

• Advances in materials Research
• /
• v.1 no.2
• /
• pp.129-146
• /
• 2012

Polycrystalline diamond is an ideal material for parts with micro-holes and has been widely used as dies and cutting tools in automotive, aerospace and woodworking industries due to its superior wear and corrosion resistance. In this research paper, the modeling and simultaneous optimization of multiple performance characteristics such as material removal rate and surface roughness of polycrystalline diamond (PCD) with ultrasonic machining process has been presented. The fuzzy logic and taguchi's quality loss function has been used. In recent years, fuzzy logic has been used in manufacturing engineering for modeling and monitoring. Also the effect of controllable machining parameters like type of abrasive slurry, their size and concentration, nature of tool material and the power rating of the machine has been determined by applying the single objective and multi-objective optimization techniques. The analysis of results has been done using the MATLAB 7.5 software and results obtained are validated by conducting the confirmation experiments. The results show the considerable improvement in S/N ratio as compared to initial cutting conditions. The surface roughness of machined surface has been measured by using the Perthometer (M4Pi, Mahr Germany).

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2007.05a
• /
• pp.39-41
• /
• 2007

본 연구는 직물 기반 바이오 모니터링 스마트 의류를 개발하기 위해 의복 소재의 신축성에 따른 심전도 신호 검출 성능과 착용 성능을 평가하여 직물 기반 심전도 의복을 위한 최적 범위를 제안하고자 한다. 이를 위해, 서로 다른 신축률의 편물을 얻기 위해 면/폴리에스테르에 스판덱스 함유율을 0%, 5%, 8%로 다르게 하여 제편하였다. 이 세 가지 소재로 심전도 측정을 위해 동일한 사이즈로 의복을 제작한 후, 금속사를 이용한 자수 기법으로 심전도 전극을 설치하였다. 심장 관련 병력이 없고 평균 BMI가 $20{\sim}24$인 정상 체중의 5명을 대상으로 Biopac MP150을 사용하여 심전도 신호를 검출한 후, 설문지를 사용하여 소재의 신축성에 따른 착용성 평가를 시행하여 신축성에 대한 만족감, 동작용이성, 전반적 쾌적함 등을 Likert 7점 척도로 평가하도록 하였다. 실험 결과, 심전도 신호 검출 성능 측면에서는 8% 라이크라 함유 소재가 가장 우수하였으나, 착용성 측면에서는 5% 소재가 가장 우수한 것으로 파악되었다. 향후 그 수요가 높아질 것으로 예상되는 바이오 모니터링 의복 소재 개발을 위해 기능성과 착용성을 모두 고려한 본 연구 결과가 유용하게 활용될 것이다.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.3 no.1
• /
• pp.28-37
• /
• 2004

An on-line monitoring system of endmill failure such as weal, chipping, and fracture is developed using AE, cutting force Characteristic variations of AE and cutting force signals due to endmill failure are identified as follows. When endmill fracture occurs, AE count rate shows a rapid Increase in conjunction with a subsequent decrease while a standard deviation of the principal cutting force Increases significantly. The increase of AE count rate precedes the Increase of standard deviation of principal cutting force. Chipping results in relatively small increase and decrease of AE count rate without any significant variation of the cutting force Gradual increase of AE count rate and mean principal cutting force are Identified to be related with the wear of cutter. A cutter fracture detection algorithm is developed based on the present results. The signals me normalized to enhance the applicability of the algorithm to Wide those of fresh cutters, and qualitative characteristics of AE signals encountered at the moment of fracture are employed. It is demonstrated that the algorithm can detect the cutter fracture successfully.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.13 no.4
• /
• pp.395-401
• /
• 2013

In-situ optical emission spectroscopy (OES) is employed for leak detection in plasma etching system. A misprocessing is reported for significantly reduced silicon etch rate with chlorine gas, and OES is used as a supplementary sensor to analyze the gas phase species that reside in the process chamber. Potential cause of misprocessing reaches to chamber O-ring wear out, MFC leaks, and/or leak at gas delivery line, and experiments are performed to funnel down the potential of the cause. While monitoring the plasma chemistry of the process chamber using OES, the emission trace for nitrogen species is observed at the chlorine gas supply. No trace of nitrogen species is found in other than chlorine gas supply, and we found that the amount of chlorine gas is slightly fluctuating. We successfully found the root cause of the reported misprocessing which may jeopardize the quality of thin film processing. Based on a quantitative analysis of the amount of nitrogen observed in the chamber, we conclude that the source of the leak is the fitting of the chlorine mass flow controller with the amount of around 2-5 sccm.