• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.431-437
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• 2017

In this study, based on the RPS algorithm, the application results to an electrically controlled suspension system using previewed road information are presented. Reducing the excessive vibration induced by a disturbance transmitted to the system and secure its stability is a major issue. In particular, in the automotive industry, the demand is constantly being raised. A typical external disturbance causing vibration and instability of a vehicle is an irregular roadway surface that contacts a running vehicle tire. Therefore, obtaining such profile information is an important process. The RPS algorithm using a multi sensor system was constructed and implemented in a real car. Through experimental work using the RPS system included non-contact type optical sensors, it could robustly reconstruct the road input profiles from the intermixed data onto the vehicle's dynamic motion while traveling at an uneven roadway surface. A controller with a preview control was designed in the framework of a semi-active suspension system based on the 7 degrees of freedom full vehicle model. The control performance of the system was evaluated through simulations and the results were compared with the passive vehicle condition. These results highlight the feasibility of the presented control frame.

• Journal of the Korea Convergence Society
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• v.12 no.9
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• pp.31-37
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• 2021

Recently, in the market of home appliances, the technical differentiation of products using convergence technology has been receiving a lot of response to satisfy consumer demand. However, air-conditioner products are an area that requires research and development in the early stages of convergence technology. In this paper, it is developed that a non-contact bio-signal(respiration, movement) collection technology using IR-UWB(Impulse-Radio Ultra Wideband) technology, which controls the air-conditioner direction according to the user's location and also monitors sleep to provide an optimal sleep environment. In addition, emotional lighting and ASMR are developed to provide a comfortable and emotional place of life. Finally, based on the developed convergence technology, we develop intelligent smart air-conditioning services for the convenience of daily life and a comfortable resting space.

• Journal of Practical Engineering Education
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• v.13 no.2
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• pp.301-304
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• 2021

In this study, we developed a module that can perform two functions at the same time through interworking between a personal recognition module and a heat detection module in the era of COVID-19. This can simultaneously solve the problem of compatibility of the personal recognition module that occurs in the existing system and the problem of secondary infection that can occur during congestion due to the separate implementation of heat detection. Therefore, in this study, NFC and Bluetooth motherboards were developed, and an array-type non-contact temperature sensor was applied to detect heat. The developed system is expected to be able to realize both access control of floating population and effective quarantine at the same time in public institutions or private companies that require AI automated access control. In addition, it is judged that it is possible to link the embedded programming and web programming implementation method using the module of the development system to the educational program.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.10
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• pp.1319-1324
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• 2020

A smart tag complements various problems caused by the expansion of the use of existing magnet cards. This emerged as a result of the need for alternative means to perform safer and more diverse functions. RFID tags are becoming increasingly ubiquitous sensor networks and Internet of Things technologies as they give everything an ID, enabling automatic recognition of objects and forming a communication network between them. In this paper, a contactless RFID smart tag reader composed of RFID tags and readers using AVR processor was developed. The system has a low frequency band of 13.56MHz and is designed by PWM method of communication velocity 26.48kbps. The developed RFID smart tag board showed a faster response rate than the typical RFID system as a result of the simulation, and the actual experiment also showed an improvement in response rate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.412-417
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• 2022

Capacitive-type humidity sensors with a high sensitivity and fast response/recovery times have attracted a great attention in non-contact respiration biological signal monitoring applications. However, complicated fabrication processes involving high-temperature heat treatment for the hygroscopic film is essential in the conventional ceramic-based humidity sensors. In this study, a non-toxic ceramic/metal halide (BaTiO₃(BT)/NaCl) humidity sensor was prepared at room temperature using a solvent-free aerosol deposition process (AD) without any additional process. Currently prepared BT/NaCl humidity sensor shows an excellent sensitivity (245 pF/RH%) and superior response/recovery times (3s/4s) due to the NaCl ionization effect resulting in an immense interfacial polarization. Furthermore, the non-contact respiration signal variation using the BT/NaCl sensor was determined to be over 700% by maintaining the distance of 20 cm between the individual and the sensor. Through the AD-fabricated sensor in this study, we expect to develop a non-contact biological signal monitoring system that can be applied to various fields such as respiratory disease detection and management, infant respiratory signal observation, and touchless skin moisture sensing button.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.4
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• pp.53-60
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• 2010

Biometrics are methods of recognizing a person based on the physiological or behavioral characteristics of his of her body. They are highly secure with little risk of loss or falsification by others. This paper has designed and implemented a security system of biometrics by precisely measuring heartbeat signals at two fingertips and using a photoplethysmogram, which is applicable to biometrics. A performance evaluation has led to the following result. The security system of biometrics for personal authentication which has been designed and implemented by this study has achieved a recognition rate of 90.5%. The security system of biometrics suggested here has merits of time saving and easy accessibility. The system is touch-based and collects the necessary biometrics information by simply touching the machine with fingers, so anyone can utilize the system without any difficulty.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.2
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• pp.58-66
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• 2023

In this study, cable tension was measured using the vibration method, and a vision-based system was applied as a sensor to measure the displacement response of a cable in a non-contact method. In the vision-based system, the camera is installed in a location that considers the target structure and the field of view of the camera. However, it can be difficult to recognize the control points required to measure the displacement response of a structure as the target structure and other structures such as vehicles may be included in the image at the intended installation location. In this study, a distorted image including a vehicle shows inaccurate results in image analysis due to the installation position of the vision-based system. Accordingly, the image including the vehicle was eliminated by calculating the similarity between the two images. To verify the validity of the method of estimating the cable tension of cable-stayed bridges using the proposed method, the vibration method was applied to cable-stayed bridges in service to measure the tension.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.28-30
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• 2022

Recently, the number of confirmed cases has increased again with the new variant of COVID-19. Quarantine is recommended, especially to prevent the rapidly increasing spread, as environmental controls, such as minimizing contact with others, can increase safety. In addition, there are often cases in which the patient's condition cannot be confirmed from the standpoint of a guardian, such as visitation being prohibited under certain conditions. At this time, the sensor data values of oxygen, carbon dioxide concentrations, temperature and humidity, and alcohol, which are medical gases used in hospitals, are collected remotely using ZigBee wireless communication technology. Design a system that can be stored and monitored in a database. We propose an environmental monitoring system, which is a visualization system designed to allow hospitals to check and feedback data on the managed environment, and to give reliability to parents.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.51-57
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• 2009

Biofouling in seawater reverse osmosis (SWRO) desalination process causes many problems such as flux decline, biodegradation of membrane, increased cleaning time, and increased energy consumption and operational cost. Therefore biofouling is considered as the most critical problem in system operation. To control biofouling in early stage, detection of the most problematic bacteria causing biofouling is required. In this study, six model bacteria were chosen; Bacillus sp., Flavobacterium sp., Mycobacterium sp., Pseudomonas aeruginosa, Pseudomonas fluorescens, and Rhodobacter sp. based on report in the literature and phylogenetic analysis of seawater intake and fouled RO membrane. The adhesion to RO membrane, the high pressure resistance, and the hydrophobicity of the six model bacteria were examined to find out their fouling potential. Rhodobacter sp. and Mycobacterium sp. were found to attach very well to RO membrane surface compared to others used in this study. The test of hydrophobicity revealed that the bacteria which have high hydrophobicity or similar contact angle with RO membrane ($63^{\circ}$ of contact angle) easily attached to RO membrane surface. P. aeruginosa which is highly hydrophilic ($23.07^{\circ}$ of contact angle) showed the least adhesion characteristic among six model bacteria. After applying a pressure of 800 psi to the sample, Rhodobacter sp. was found to show the highest reduction rate; with 59-73% of the cells removed from the membrane under pressure. P. fluorescens on the other hand analyzed as the most pressure resistant bacteria among six model bacteria. The difference between reduction rates using direct counting and plate counting indicates that the viability of each model bacteria was affected significantly from the high pressure. Most cells subjected to high pressure were unable to form colonies even thought they maintained their structural integrity.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.297-307
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• 2010

Recently, maintenance engineering and technology for civil and building structures have begun to draw big attention and actually the number of structures that need to be evaluate on structural safety due to deterioration and performance degradation of structures are rapidly increasing. When stiffness is decreased because of deterioration of structures and member cracks, dynamic characteristics of structures would be changed. And it is important that the damaged areas and extent of the damage are correctly evaluated by analyzing dynamic characteristics from the actual behavior of a structure. In general, typical measurement instruments used for structure monitoring are dynamic instruments. Existing dynamic instruments are not easy to obtain reliable data when the cable connecting measurement sensors and device is long, and have uneconomical for 1 to 1 connection process between each sensor and instrument. Therefore, a method without attaching sensors to measure vibration at a long range is required. The representative applicable non-contact methods to measure the vibration of structures are laser doppler effect, a method using GPS, and image processing technique. The method using laser doppler effect shows relatively high accuracy but uneconomical while the method using GPS requires expensive equipment, and has its signal's own error and limited speed of sampling rate. But the method using image signal is simple and economical, and is proper to get vibration of inaccessible structures and dynamic characteristics. Image signals of camera instead of sensors had been recently used by many researchers. But the existing method, which records a point of a target attached on a structure and then measures vibration using image processing technique, could have relatively the limited objects of measurement. Therefore, this study conducted shaking table test and field load test to verify the validity of the method that can measure multi-point displacement responses of structures using image processing technique.