• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.1007-1013
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• 2005

In this study, a step-down piezoelectric transformer was fabricated to utilize as an adapter for charging batteries of mobile electronic appliances. The ceramic part of the transformer is $Pb[(Mn_{1/3}Sb_{2/3})_{_0.05}Zr_{0.475}Ti_{0.475}]O_3$ with mechanical quality factor of 1600, electromechanical coupling coefficient $59\%$, and piezoelectric constant $d_{33}$ 1300, which can be utilized as a piezoelectric transformer. A simply fabricated disk-typed test pattern of diameter 28 mm and thickness 2 mm was used to characterize output voltage, step-down ratio as a function of electrode area with the input remained constant, and power, efficiency as a function of input voltage, and temperature-dependent electric characteristics were evaluated. The sample APT1 showed the best properties. The highest admittance, effective electromechanical coupling coefficient and an appropriate mechanical quality factor were obtained at the sample with the input/output area ratio of 1:1.5 at the common electrode, and the condition of 20 $V_{rms}$, $50\;\Omega$ made the maximum efficiency of $95\%$. The temperature was increased by 14.7'E as the input voltage was increased for $50\;V_{rms},\;50\;\Omega$.

• Journal of the Korea Society of Computer and Information
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• v.23 no.2
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• pp.45-51
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• 2018

In this paper, we propose a Designed and Developed home router management system. Through the fourth industrial revolution and development of IoT technology, now people can experience a wide range of IoT related services at their workplace or daily lives. At the industrial site, IoT devices are used to improve productivity such as factory automation, and at home, IoT technology is used to control home appliances from a remote distance. Usually IoT device is integrated and controlled by the router. Home router connects different IoT devices together at home, however when security issues arise, it can invade personal privacy. Even though these threats exist, the perception for home router security is still insufficient. In this paper, we have designed and developed home router management system using DEVS methodology to promote the safe use of home router. Through the DEVS methodology, we have designed the system and developed the mobile application. This management system enables users to set up security options for home router easily.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.613-618
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• 2019

EMF (Electromagnetic Field) is a valuable resource for living in a knowledge-based information society. The EMF is used in home appliances that make our lives easy and convenient, and in telecommunication devices such as mobile phones, personal computers, medical devices and broadcasting towers. However, the biological hazards associated with EMF exposure are also increasing in signal from telecommunication devices. Studies of the effects of EMF exposure on humans have been conducted for a long time, but it has not yet been demonstrated whether the EMF effect is harmful. In this paper, we examine the electromagnetic field emitted from various electronic devices around living and its effect.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.94-100
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• 2024

Recently, as interest in personal hygiene has increased due to the community spread of COVID-19 and variant viruses, fixed and potable UV germicidal equipment to sterilize indoor spaces and hand-held UV germicidal equipment to sterilize household items such as masks and mobile phones are continuously being developed and sold. However, the development and sales of the product are difficult because appropriate testing methods have not yet been established. In this situation, if an uncertified product is distributed in the market, it can cause serious harm to consumers. In this study, we investigate the photobiological risks and safety devices against UV exposure of UV germicidal equipment distributed domestically, and propose appropriate test methods for portable UV germicidal equipment based on the research results.

• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.128-135
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• 2012

In this paper, we proposed a system and a scenario to raise efficiency of gas safety management by developing wireless ZigBee communication modules, smart-home gas safety appliances and the system suitable for gas safety. Our designed system consists of a micom gas meter, an automatic extinguisher, sensors, and a wall-pad. A micom-gas-meter monitors gas flow, gas pressure, and earthquake. An automatic fire extinguisher checks combustible gas leaks and temperature of $100^{\circ}C$(cut off) and $130^{\circ}C$(fire). Sensors measure smoke and CO gas. In our novel system, a micom-gas meter cut off inner valve with warnings, an automatic fire extinguisher cut off middle valve and spray extinguishing materials, and sensors generate signals when detecting smoke and CO and then take a next action. Gas safety appliances and sensors automatically takes measures, and transmit those information to a wall-pad. The wall-pad again transmits real time information to server. Users can check and manage gas safety situations by connecting BcN server through web or mobile application. We hereby devised scenarios for gas safety and risk management based on the smart, and demonstrated their efficiency through test applied to filed.

• Science of Emotion and Sensibility
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• v.13 no.3
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• pp.501-510
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• 2010

The knowledge base on emotional information is one of the key elements in the implementation of emotion retrieval systems for contents design of Mobile devices. This study proposed a new approach to the knowledge base implementation by automatically extracting color components from full-color images. In this study, the validity of the proposed method was empirically tested. Database was developed using 100 interior images as visual stimuli and a total of 48 subjects participated in the experiment. In order to test the reliability of the proposed 'emotional information knowledge base', firstly 'recall ratio' that refers to frequencies of correct images from the retrieved images was derived. Secondly, correlation Analysis was performed to compare the ratings by the subjects to what the system calculated. Finally, the rating comparison was used to run a paired-sample t-test. The analysis demonstrated satisfactory recall ration of 62.1%. Also, a significant positive correlation (p<.01) was observed from all the emotion keywords. The paired Sample t-test found that all the emotion keywords except "casual" retrieved the images in the order from more relevant to less relevant images and the difference was statistically significant (t(9)=5.528, p<.05). Findings of this study support that the proposed 'emotional information knowledge base' established only with color information automatically extracted from images can be effectively used for such visual stimuli search tasks as commercial interior images.

• Journal of the Korea Society of Computer and Information
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• v.17 no.8
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• pp.99-106
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• 2012

In recent years, many researchers studies to promote the welfare of disabled people using IT technology. In particular, their suggestions are used a lot of mobile sensor installed on the street. These systems are acquired and to store the data sent to the server over the network, and by analyzing the users life log to judge of their risk state. In particular, persons with disabilities are exposed to various risks. So, they must need to the guardians if he go out. Thus, this study is a method for alleviating these so much pressure to smart appliances and impaired life log analysis system.

• Journal of Korea Multimedia Society
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• v.16 no.2
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• pp.206-212
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• 2013

Information and Communications Technologies(ICT) represented by Multimedia, Virtual Reality and Network could be used as the better ways to preserve and restore the original shape of cultural contents. This paper presents the detailed methods of Multimedia and Virtual Reality technologies to digitally implement the traditional wooden buildings which are called as a typical 'Korean Cultural Content." We implemented a 3D modeling of architectural parts, realized a roof curve, and texture-mapped the material qualities of traditional wooden buildings by using Graphic techniques. In addition, the information, which is implemented by marker-based Augment Reality, for the traditional wooden buildings can be obtained through the mobile appliances such as a smart phone. We, also, presented how to practically use the implemented digital Korea traditional wooden buildings.

• Journal of the Korea Society of Computer and Information
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• v.10 no.6 s.38
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• pp.355-364
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• 2005

Ubiquitous environment can be supported by various service on networked appliance, sensors and devices. In home network and telematics, open service gateway is widely used for ubiquitous environment and Present environment for service installation, deployment and execution. Service gateway is a middle layer which is located between service and various devices in ubiquitous environment and offers a unique opportunity for pervasive computing as a potential framework for achieving interoperability between various sensors, home appliances. and networked devices. In ubiquitous environments, these services must support the mobility among service gateway because users and devices has a mobility characteristic. However the OSGi framework supports only a remote installation of a bundle, which is a unit that installs and deploys services. This paper develops a system that can manage bundles for supporting this dynamic bundle's mobility between service gateway. This system we are proposing implements a bundle form which can perform in an OSGi framework as well as manage the mobile services. As a result, mobility in a ubiquitous computing environment will be supported more efficiently.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.56-61
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• 2011

A class-D audio amplifier is widely used in coil speaker. This paper presented the technique for applying a class-D audio amplifier to the ceramic flat speaker. This technique can be achieved by employing a matching transmitter in order to replace class-G amplifier that is drven by voltage level to class-D amplifier employing power driving method. Consequently, the presented technique can improve the efficiency by making the voltage driving level a litter larger. We evaluate the sound-level efficiency using the various mediums such as wood, plastic, and paper. From the simulation results, the proposed technique employing a class-D audio amplifier rather than a class-G one showed a 10% improvement. The proposed system can be applicable for the mobile appliances as an external slim speaker.