• 전자공학회논문지 IE
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• v.46 no.3
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• pp.55-61
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• 2009

This paper describes an assistant system for elders who live alone. The developed system is composed of a wearable RFID system, a gateway system, and server system. The wearable RFID system is installed in glove. The wearable RFID system can be considered as a wireless sensor network which has a sink node and sensor node with a RFID reader. The sensor node can read RFID tags on the various objects used in daily living such as furniture, medicines, sugar and salt bottles, and ok. The sensor node transmits wireless packets to the sink node. The sink node sends the received packet immediately to a server system via a gateway system. The gateway provides users with audio-visual information of objects. The server system is composed of a database server and a web server. The data from each wearable RFID system is collected into a database, and then the data are processed to visualize the measurement of daily living activities of users. The processed data can be provided for someone who wants to know about user's daily living patterns in house such as family, caregivers, and medical crew.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.6
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• pp.53-58
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• 2004

A novel UV sensor was manufactured and characterized using evanescent field coupling between photochromic dye dispersed polymer waveguide and side polished fiber. The spiroxazine (photochromic dye) dispersed polymer was used as planar waveguides. The resonant wavelength was shifted owing to refractive index variation of planar waveguide on exposed UV because of its photo-functional properties. The sensitivities are $1.21{\mu}W/mw$ and $2.75{\mu}W/mw$ when UV intensities increased after exposure times were fixed at 3 seconds and 5 seconds, respectively. Output optical power according to UV intensity increases and saturation time decreases as the intensity of UV radiations increases.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.7
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• pp.17-22
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• 2010

We have proposed and experimentally demonstrated a novel fiber Bragg grating (FBG) sensing interrogation method using bidirectional modulation of a Mach-Zehnder electro-optical modulator (MZ-EOM). The proposed structure consists mainly of a broadband light source (BBS), FBG, MZ-EOM, chirped fiber Bragg grating (CFBG), and photodetector (PD). We have obtained the transfer functions of the proposed structure and calculated the time delay from the change in the free spectral range (FSR) for ten wavelengths over the frequency range of 505 MHz to 525 MHz. The results show that the time delay and the wavelength variation have a good linear relationship with a gradient of 12.9 ps/0.2 nm, which can be usefully applied to FBG strain or temperature sensors and other multiplexed sensor applications.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.3
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• pp.277-282
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• 2016

Effect of spectral drift in coherent fiber laser was investigated by injecting optical feedback to Fabry-Perot resonance loop. Er+3 doped fiber laser having unilateral optical feedback loop in Fabry-Perot configuration using two FBGs was fabricated. The optical feedback was found to be effective in linewidth reduction of fiber laser compared to the case without any optical feedback. The linewidth of three fiber lasers using above configuration were measured to be within 3kHz which is resolution-limited performance of self-heterodyne linewidth measurement set-up. The frequency drift measurement using Mach-Zehnder measurement set-up having 200m optical delay-line in one arm showed that the frequency drift rate of optical feedback fiber laser was measured as 300kHz/sec which was better than the case without optical feedback.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.57-63
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• 2001

The wound rotor type induction motor(WRIM) control system which is widely used in the industry has many maintenance problem because of external resistors and magnetic contactors. In this paper, the simple sensorless vector control algorithm for WRIM is proposed without any additional devices except detecting rotor currents. Because the external resistors are disconnectd and the rotor slip rings are shorten, the power loss due to external resistors is removed and the maintenance problem is improved remarkably. Also, the vector control performance becomes better because the proposed sensorless vector control algorithm does not use the rotor resistance which is usually used to estimate the slip frequency in case of indirect vector control scheme. The proposed algorithm is verified by the digital simulation and the experiment.

• The Journal of Korean Institute of Information Technology
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• v.16 no.12
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• pp.57-68
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• 2018

A system to prevent disasters by collecting and analyzing environmental information such as road surface sedimentation, sinkholes, collapse risk of bridges, temperature and humidity around tram station is continuously monitored by monitoring the condition of road surface when constructing tram which is one of the urban railways. In this paper, we propose a wireless network security management system for tram roads based on LPWA that can recognize risk factors of road surface, bridge and tram station of tram in advance and prevent risk. The proposed system consists of a sensor node that detects the state of the tram road surface, a gateway that collects sensor information, and a safety management system that monitors the safety and environmental conditions of the tram road surface, and applies the low power long distance communication technology. As a result of comparing the proposed system with the LTE system in the field test, it was confirmed that there is no significant difference between the sensor information value and the critical alarm level in the monitoring system.

• Journal of IKEEE
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• v.26 no.2
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• pp.219-225
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• 2022

The textile industry in Korea, the dyeing sector is an energy-intensive sector and has low per-unit productivity due to its labor-intensive nature. If the defective rate of dyed fabrics is high, additional costs are incurred due to an increase in production cost due to re-dyeing. Therefore, the goal of the dyeing factory was to minimize the defect rate rather than to save energy. It was difficult to check the dyeing state of the fabric in real time due to the risk of accidents due to burns or pressure when dyeing in a high-temperature and high-pressure environment. In this paper, a complex sensor that can measure the exhaustion rate of dye solution in the dyeing machine using turbidity, pH, and conductivity sensors was proposed, and the experimental method and experimental results were analyzed.

• Journal of IKEEE
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• v.26 no.3
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• pp.396-400
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• 2022

In this study, an ICT-based underwater communication monitoring device for underwater structures is implemented based on lifting fixture that transport human bodies found on the seabed to sea level. The lifting fixture is packaged with a retback, sideback, and cartridge that injects air. Monitoring systems are developed in a mobile manner in a portable structure. The underwater ultrasonic sensor signal is supplied using a USB port, and the O/S consists of Linux. For the underwater communication dong test, a measurement test was conducted in real time from 6m to 40m in depth on the east coast. The ultrasonic sound sensor is converted to 2,400 bps to verify the transmission error according to the duality. The communication speed of sensor to monitoring is 115,200 bps, and the speed of communication from controller to receiver is 2,400 bps. In the commercialization stage of the lifting device, it is easy to develop a low-end type and the compatibility is wide.

• Journal of IKEEE
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• v.26 no.3
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• pp.364-372
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• 2022

This paper proposes the design and implementation results for human and object classification systems utilizing frequency modulated continuous wave (FMCW) radar sensor. Such a system requires the process of radar sensor signal processing for multi-target detection and the process of deep learning for the classification of human and object. Since deep learning requires such a great amount of computation and data processing, the lightweight process is utmost essential. Therefore, binary neural network (BNN) structure was adopted, operating convolution neural network (CNN) computation in a binary condition. In addition, for the real-time operation, a hardware accelerator was implemented and verified via FPGA platform. Based on performance evaluation and verified results, it is confirmed that the accuracy for multi-target classification of 90.5%, reduced memory usage by 96.87% compared to CNN and the run time of 5ms are achieved.

• Journal of the Korean Electrochemical Society
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• v.11 no.3
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• pp.170-175
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• 2008

Screen printed carbon electrodes (SPEs) modified with co-immobilized osmium-based redox polymers can be used to apply multi-detecting biosensors. In this study, we report our initial studies of multi-detecting biosensor concepts using two osmium-based redox polymers for horseradish peroxidase-mediated reduction of ${H_2}{O_2}$ coupled to glucose oxidase-mediated oxidation of glucose. We target to synthesize two osmium redox polymers of potentials use, a chloride-containing redox polymer ($E^{O'}$ + 0.520 vs. Ag/AgCl) and a methoxy-containing redox polymer $E^{O'}$ + 0.150 vs. Ag/AgCl). The former show good catalytic electrical signals with horseradish peroxidase and the latter's redox polymer is to be an effective redox mediator of glucose oxidation by glucose oxidase.