• Design Convergence Study
• /
• v.16 no.6
• /
• pp.123-135
• /
• 2017

In recent mobile health care service, health management using number of steps is becoming popular. In addition, a variety of activity trackers have made it possible to measure the number of steps more accurately and easily. Nevertheless, the activity tracker is not popularized, and it is a trend to use the pedometer sensor of the smartphone as an alternative. In this study, we tried to find out how much the number of steps collected by the smartphone versus the actual number of steps in actual situations, and what factors make the difference. We conducted an experiment to collect number of steps data of 21 people using the smartphone and wearable device simultaneously for 7 days. As a result, we found that the average number of steps of the smartphone is 62% compared to the actual number of steps, and that there is a large variation among users. We derived a regression model in which the accuracy of smartphone increases with the degree of awareness of smartphone. We expect that this can be used as a factor to correct the difference from the actual number of steps in the smartphone alone healthcare service.

• Journal of the Korean Applied Science and Technology
• /
• v.36 no.4
• /
• pp.1253-1258
• /
• 2019

The solid-state electrolyte based on polymer is applicable to various electrochemical devices including supercapacitor, battery, sensor, actuator and has great attention to develop its ionic conductivity from conventional polymer electrolyte by uisng wide range of ionic liquids. The research about ion gel as a solid state electrolyte with the ionic liquid has focused on the wearable and flexible electronic device to use as the high electrical and electrochemical performances, mechanical strength of polymer. In this work, we have investigated and developed solid-state electrolyte based on the ionic liquid and polymer with enhanced ionic conductivity and stability.

• Journal of the Institute of Convergence Signal Processing
• /
• v.19 no.1
• /
• pp.14-19
• /
• 2018

Recently, the smart health care industry has been rising rapidly and interest and efforts for public health have been greatly increased. As a result, the public does not visit medical specialists and medical facilities, but the desire to check their health condition in everyday life is increased. Therefore, many domestic and foreign companies continuously research and develop wearable devices that can measure body activity information anytime and anywhere And the market. Especially, it is used for heart activity measurement device using pulse wave sensor and electrocardiogram sensor. However, in this study, a monitoring system that can detect cardiac activity using cardiac sounds, heart sound measurement rather than pulse wave measurement and electrocardiogram measurement, was performed and its performance was evaluated. Experimental results confirmed the predictability of cardiac heart rate and heart valve disease during daily living.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2019.05a
• /
• pp.510-512
• /
• 2019

Recently, there have been growing requirements in the public safety sector to ensure safety through detection of hazardous situations or preemptive predictions. It is noteworthy that various sensor data can be analyzed and utilized as a result of mobile device's dissemination, and many advantages can be used in terms of safety and security. An effective modeling technique is needed to combine sensor data generated by smart-phones and wearable devices to analyze users' moving patterns and behavioral patterns, and to ensure public safety by fusing location-based crime risk data provided.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.2
• /
• pp.397-407
• /
• 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.

• Journal of the Microelectronics and Packaging Society
• /
• v.24 no.4
• /
• pp.31-37
• /
• 2017

Recently, there has been substantial interest in flexible and wearable devices whose properties and performances are close to conventional devices on hard substrates. Despite the advancement on flexible devices with organic semiconductors or carbon nanotube films, their performances are limited by the carrier scattering at the molecular to molecular or nanotube-to-nanotube junctions. Here in this study, we demonstrate on the vertical semiconductor crystal array embedded in flexible polymer matrix. Such structures can relieve the strain effectively, thereby accommodating large flexural deformation. To achieve such structure, we first established a low-temperature solution-phase synthesis of single crystalline 3D architectures consisting of epitaxially grown ZnO constituent crystals by position and growth direction controlled growth strategy. The ZnO vertical crystal array was integrated into a piece of polydimethylsiloxane (PDMS) substrate, which was then mechanically detached from the hard substrate to achieve the freestanding ZnO-polymer composite. In addition, the characteristics of transferred ZnO were confirmed by additional structural and photoluminescent measurements. The ZnO vertical crystal array embedded in PDMS was further employed as pressure sensor that exhibited an active response to the external pressure, by piezoelectric effect of ZnO crystal.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.6
• /
• pp.1148-1153
• /
• 2016

The number of cyclists is on the steady growing for leisure and transportation with the increasing interest in health and environment. However, the number of cycling accidents is also increasing steadily due to the lack of safety awareness and regulations. Focusing on this issue, we propose and develop a smart LED bicycle helmet in order to reduce a risk of cycling accident. The main idea is to change status of the LED on the helmet based on the bicycle's movement and provide motion information of the bicycle for others. To control the LED lights on the helmet, we use the Arduino board which communicates with the LED module through serial connection. We decide motion information by using the values from acceleration and GPS sensors of the smartphone. To receive this information from the smartphone, the control board and the smartphone are connected by Bluetooth.

• Journal of Digital Convergence
• /
• v.15 no.3
• /
• pp.187-193
• /
• 2017

Objects Internet-based healthcare services provide healthcare and healthcare services, including measurement of user's vital signs, diagnosis and prevention of diseases, through a variety of object internet devices. However, there is a problem that new security vulnerability can occur when inter-working with the security weakness of each element technology because the internet service based on the object Internet provides a service by integrating various element technologies. In this paper, we propose a user privacy protection model that can securely process user's healthcare information from a third party when delivering healthcare information of users using wearable equipment based on IoT in a mobile environment to a server. The proposed model provides attribute values for each healthcare sensor information so that the user can safely handle, store, and store the healthcare information, thereby managing the privacy of the user in a hierarchical manner. As a result of the performance evaluation, the throughput of IoT device is improved by 10.5% on average and the server overhead is 9.9% lower than that of the existing model.

• Journal of the Semiconductor & Display Technology
• /
• v.18 no.3
• /
• pp.122-126
• /
• 2019

These-days technology related to IoT (Internet of Thing) is widely used and there are many types of smart system based IoT like smart health, smart building and so on. In smart health system, it is possible to check someone's health by analyzing data from wearable IoT device like smart watch. Smart building system aims to collect data from sensor such as humidity, temperature, human counter like that and control the building for energy efficiency, security, safety and so forth. Furthermore, smart city system can comprise several smart systems like smart building, smart health, smart mobility, smart energy and etc. In this paper, we propose multimedia IoT based intelligent emergency alarm system for smart city. In existing IoT based smart system, it communicates lightweight data like text data. In the past, due to network's limitations lightweight IoT protocol was proposed for communicating data between things but now network technology develops, problem which is to communicate heavy data is solving. The proposed system obtains video from IP cameras/CCTVs, analyses the video by exploiting AI algorithm for detecting emergencies and prevents them which cause damage or death. If emergency is detected, the proposed system sends warning message that emergency may occur to people or agencies. We built prototype of the intelligent emergency alarm system based on MQTT and assured that the system detected dangerous situation and sent alarm messages. From the test results, it is expected that the system can prevent damages of people, nature and save human life from emergency.

• Journal of Korea Society of Industrial Information Systems
• /
• v.25 no.2
• /
• pp.129-136
• /
• 2020

Recognizing finger movements have been used as a intuitive way of human-computer interaction. In this study, we implement an wearable device for finger motion recognition and evaluate the accuracy of several ML (Machine learning) techniques. Not only HMM (Hidden markov model) and DTW (Dynamic time warping) techniques that have been traditionally used as time series data analysis, but also NN (Neural network) technique are applied to compare and analyze the accuracy of each technique. In order to minimize the computational requirement, we also apply the pre-processing to each ML techniques. Our extensive evaluations demonstrate that the NN-based gesture recognition system achieves 99.1% recognition accuracy while the HMM and DTW achieve 96.6% and 95.9% recognition accuracy, respectively.