• Title/Summary/Keyword: Wearable Electronic Devices

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Development of Multi-layer Pressure Sensor using PEDOT Vapor Phase Polymerization (PEDOT 기상중합 원단을 이용한 멀티 레이어 압력 센서 개발)

  • Lim, Seung Ju;Bae, Jong Hyuk;Jang, Seong Jin;Lim, Jee Young;Park, Keun Hae;Ko, Jae Hoon
    • Journal of Sensor Science and Technology
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    • v.27 no.3
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    • pp.186-191
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    • 2018
  • Smart textile industries have been precipitously developed and extended to electronic textiles and wearable devices in recent years. In particular, owing to an increasingly aging society, the elderly healthcare field has been highlighted in the smart device industries, and pressure sensors can be utilized in various elderly healthcare products such as flooring, mattress, and vital-sign measuring devices. Furthermore, elderly healthcare products need to be more lightweight and flexible. To fulfill those needs, textile-based pressure sensors is considered to be an attractive solution. In this research, to apply a textile to the second layer using a pressure sensing device, a novel type of conductive textile was fabricated using vapor phase polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). Vapor phase polymerization is suitable for preparing the conductive textile because the reaction can be controlled simply under various conditions and does not need high-temperature processing. The morphology of the obtained PEDOT-conductive textile was observed through the Field Emission Scanning Electron Microscope (FESEM). Moreover, the resistance was measured using an ohmmeter and was confirmed to be adjustable to various resistance ranges depending on the concentration of the oxidant solution and polymerization conditions. A 3-layer 81-point multi-pressure sensor was fabricated using the PEDOT-conductive textile prepared herein. A 3D-viewer program was developed to evaluate the sensitivity and multi-pressure recognition of the textile-based multi-pressure sensor. Finally, we confirmed the possibility that PEDOT-conductive textiles could be utilized by pressure sensors.

Alternative Sintering Technology of Printed Nanoparticles for Roll-to-Roll Process (롤투롤 인쇄공정 적용을 위한 차세대 나노입자 소결 기술)

  • Lee, Eun Kyung;Eun, Kyoungtae;Ahn, Young Seok;Kim, Yong Taek;Chon, Min-Woo;Choa, Sung-Hoon
    • Journal of the Microelectronics and Packaging Society
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    • v.21 no.4
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    • pp.15-24
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    • 2014
  • Recently, a variety of printing technologies, including ink jet, gravure, and roll-to-roll (R2R) printing, has generated intensive interest in the application of flexible and wearable electronic devices. However, the actual use of printing technique is much limited because the sintering process of the printed nanoparticle inks remains as a huge practical drawback. In the fabrication of the conductive metal film, a post-sintering process is required to achieve high conductivity of the printed film. The conventional thermal sintering takes considerable sintering times, and requires high temperatures. For application to flexible devices, the sintering temperature should be as low as possible to minimize the damage of polymer substrate. Several alternative sintering methods were suggested, such as laser, halogen lamp, infrared, plasma, ohmic, microwave, and etc. Eventually, the new sintering technique should be applicable to large area, R2R, and polymer substrate as well as low cost. This article reviews progress in recent technologies for several sintering methods. The advantages and disadvantages of each technology will be reviewed. Several issues for the application in R2R process are discussed.

Maximum Power Point Tracking Method Without Input side Voltage and current Sensor of DC-DC Converter for Thermoelectric Generation (열전발전을 위한 DC-DC Converter의 입력측 전압·전류 센서없는 최대전력점 추적방식)

  • Kim, Tae-Kyung;Park, Dae-Su;Oh, Sung-Chul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.3
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    • pp.569-575
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    • 2020
  • Recently, research on renewable energy technologies has come into the spotlight due to rising concerns over the depletion of fossil fuels and greenhouse gas emissions. Demand for portable electronic and wearable devices is increasing, and electronic devices are becoming smaller. Energy harvesting is a technology for overcoming limitations such as battery size and usage time. In this paper, the V-I characteristic curve and internal resistance of thermal electric devices were analyzed, and MPPT control methods were compared. The Perturbation and Observation (P&O) control method is economically inefficient because two sensors are required to measure the voltage and current of a Thermoelectric Generator(TEG). Therefore, this paper proposes a new MPPT control method that tracks MPP using only one sensor for the regulation of the output voltage. The proposed MPPT control method uses the relationship between the output voltage of the load and the duty ratio. Control is done by periodically sampling the output voltage of the DC-DC converter to increase or decrease the duty ratio to find the optimal duty ratio and maintain the MPP. A DC-DC converter was designed using a cascaded boost-buck converter, which has a two-switch topology. The proposed MPPT control method was verified by simulations using PSIM, and the results show that a voltage, current, and power of V=4.2 V, I=2.5 A, and P=10.5 W were obtained at the MPP from the V-I characteristic curve of the TEG.

Study on the Piezoelectric Energy Harvesting Technology for the Energy Conversion of Vibration in Automobiles (자동차 진동 에너지 변환을 위한 압전 에너지 하베스팅에 관한 연구)

  • Lee, Hyeon Yeong;Kim, Kwangwon;Ye, Jiwon;Woo, Suhyeon;Lee, Geon;Lee, Seungah;Jeong, Seong Rok;Jeong, Seon Hye;Kim, Ho Seong;Nam, Ga Hyeon;Jo, Yun Yeong;Choi, Han Seung;Ryu, Jungho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.34 no.6
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    • pp.495-504
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    • 2021
  • Energy Harvesting is a technology that can convert wasted energy such as vibration, heat, light, electromagnetic energy, etc. into usable electrical energy. Among them, vibration-based piezoelectric energy harvesting (PEH) has high energy conversion efficiency with a small volume; thus, it is expected to be used in various autonomous powering devices, such as implantable medical devices, wearable devices, and energy harvesting from road or automobiles. In this study, wasted vibration energy in an automobile is converted into electrical energy by high-power piezoelectric materials, and the generated electrical energy is found to be an auxiliary power source for the operation of wireless sensor nodes, LEDs, etc. inside an automobile. In order to properly install the PEH in an automobile, vibration characteristics includes frequency and amplitude at several positions in the automobile is monitored initially and the cantilever structured PEH was designed accordingly. The harvesting properties of fabricated PEH is characterized and installed into the engine part of the automobile, where the vibration amplitude is stable and strong. The feasibility of PEH is confirmed by operating electric components (LEDs) that can be used in practice.

Technology of Sensors with Human Sensitivity (인간과 같은 감도를 가진 오감센서 기술)

  • Song, Byung-Taeck
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.8 no.6
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    • pp.507-514
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    • 2015
  • The Internet of Things era is approaching where all the things are equipped with smart sensors and communicate through internet. The three core technologies of the Internet of Things are 'detection technology' to get information from things and the environment, 'wired and wireless communications and network infrastructure skills' that support to connect things to the internet, and 'service interface technology' that processes the information appropriate to various services. Smart sensor application can expand to smartphone, smart cars, smart home systems, wearable electronic devices, telemedicine systems, and environmental monitoring systems, etc. In particular, technologies that mimic the five human senses. This study reviews the biological principles of the human senses and the principles of operation, research & development status, technology trends and market analysis of the sensors.

Data Processing and Visualization Method for Retrospective Data Analysis and Research Using Patient Vital Signs (환자의 활력 징후를 이용한 후향적 데이터의 분석과 연구를 위한 데이터 가공 및 시각화 방법)

  • Kim, Su Min;Yoon, Ji Young
    • Journal of Biomedical Engineering Research
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    • v.42 no.4
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    • pp.175-185
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    • 2021
  • Purpose: Vital sign are used to help assess the general physical health of a person, give clues to possible diseases, and show progress toward recovery. Researchers are using vital sign data and AI(artificial intelligence) to manage a variety of diseases and predict mortality. In order to analyze vital sign data using AI, it is important to select and extract vital sign data suitable for research purposes. Methods: We developed a method to visualize vital sign and early warning scores by processing retrospective vital sign data collected from EMR(electronic medical records) and patient monitoring devices. The vital sign data used for development were obtained using the open EMR big data MIMIC-III and the wearable patient monitoring device(CareTaker). Data processing and visualization were developed using Python. We used the development results with machine learning to process the prediction of mortality in ICU patients. Results: We calculated NEWS(National Early Warning Score) to understand the patient's condition. Vital sign data with different measurement times and frequencies were sampled at equal time intervals, and missing data were interpolated to reconstruct data. The normal and abnormal states of vital sign were visualized as color-coded graphs. Mortality prediction result with processed data and machine learning was AUC of 0.892. Conclusion: This visualization method will help researchers to easily understand a patient's vital sign status over time and extract the necessary data.

Smoke Modeling and Rendering Techniques using Procedural Functions (절차적 함수를 이용한 연기 모델링 및 렌더링 기법)

  • Park, Sang-Hyun
    • The Journal of the Korea institute of electronic communication sciences
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    • v.17 no.5
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    • pp.905-912
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    • 2022
  • Virtual reality, one of the core technologies of the 4th industrial revolution, is entering a new phase with the spread of low-cost wearable devices represented by Oculus. In the case of disaster evacuation drills, where practical training is almost impossible due to the risk of accidents, virtual reality is becoming a new alternative that enables effective training. In this paper, we propose a smoke modeling method that can be applied to fire evacuation drills implemented with virtual reality technology. In the event of a fire, smoke spreads along the aisle, and the density of the smoke changes over time. The proposed method models the smoke by applying a procedural function that can reflect the density of smoke calculated through simulation to the model in real-time. Implementation results in the background of the factory show that the proposed method produces models that can express the smoke according to the user's movement.

Design of a Low Noise 6-Axis Inertial Sensor IC for Mobile Devices (모바일용 저잡음 6축 관성센서 IC의 설계)

  • Kim, Chang Hyun;Chung, Jong-Moon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.2
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    • pp.397-407
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    • 2015
  • In this paper, we designed 1 chip IC for 3-axis gyroscope and 3-axis accelerometer used for various IoT/M2M mobile devices such as smartphone, wearable device and etc. We especially focused on analysis of gyroscope noise and proposed new architecture for removing various noise generated by gyroscope MEMS and IC. Gyroscope, accelerometer and geo-magnetic sensors are usually used to detect user motion or to estimate moving distance, direction and relative position. It is very important element to designing a low noise IC because very small amount of noise may be accumulated and affect the estimated position or direction. We made a mathematical model of a gyroscope sensor, analyzed the frequency characteristics of MEMS and circuit, designed a low noise, compact and low power 1 chip 6-axis inertial sensor IC including 3-axis gyroscope and 3-axis accelerometer. As a result, designed IC has 0.01dps/${\sqrt{Hz}}$ of gyroscope sensor noise density.

Error Correction of Real-time Situation Recognition using Smart Device (스마트 기기를 이용한 실시간 상황인식의 오차 보정)

  • Kim, Tae Ho;Suh, Dong Hyeok;Yoon, Shin Sook;Ryu, KeunHo
    • Journal of Digital Contents Society
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    • v.19 no.9
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    • pp.1779-1785
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    • 2018
  • In this paper, we propose an error correction method to improve the accuracy of human activity recognition using sensor event data obtained by smart devices such as wearable and smartphone. In the context awareness through the smart device, errors inevitably occur in sensing the necessary context information due to the characteristics of the device, which degrades the prediction performance. In order to solve this problem, we apply Kalman filter's error correction algorithm to compensate the signal values obtained from 3-axis acceleration sensor of smart device. As a result, it was possible to effectively eliminate the error generated in the process of the data which is detected and reported by the 3-axis acceleration sensor constituting the time series data through the Kalman filter. It is expected that this research will improve the performance of the real-time context-aware system to be developed in the future.

Measurement and Compensation of Synchronization Error in Offset Printing Process (오프셋 인쇄에서의 동기화 오차 정밀 계측 및 보정 연구)

  • Kang, Dongwoo;Kim, Hyunchang;Lee, Eonseok;Choi, Young-Man;Jo, Jeongdai;Lee, Taik-Min
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.6
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    • pp.477-481
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    • 2014
  • Flexible electronics have been to the fore because it is believed that flexibility can add incredible value such as light weight and mobility into the existing electronic devices and create new markets of large-area and low-cost electronics such as wearable eletronics in near future. Offset printing processes are regarded as major candidates for manufacturing the flexible electronics because they can provide the patterning resolution of micron-size effectively in large-area. In view of mechanics, the most important viewpoint in offset printing is how to achieve the synchronized movement of two contact surfaces in order to prevent slip between two contact surfaces and distortion of the blanket surface during ink transfer so that the high-resolution and good-overlay patterns can be printed. In this paper, a novel low-cost measurement method of the synchronization error using the motor control output signals is proposed and the compensation method is presented to minimize the synchronization error.