• Journal of Engineering Education Research
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• v.21 no.2
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• pp.39-50
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• 2018

In the 4th industrial revolution, the maker movement is spreading around the world with the fusion of advanced technology with product manufacturing. Already in developed countries such as the US and Japan, the emphasis is on maker education that integrates education into traditional makers' movement. Through this, we are fostering young talents who will lead the fourth industrial revolution era. Domestic maker education is mainly performed in the maker space, and is limited to the IT field using Arduino and App-Inventor. Therefore, it has the limitation of fostering IT-oriented makers. Therefore, it is affecting the proliferation of the maker's movement because of the difficulty of participation of the general public. The purpose of this study was to understand the characteristics of maker 's movement and to suggest the direction of Korean maker education. In order to accomplish the purpose of research, we analyzed the case of convergent maker education at D Creation Economic Innovation Center, which combines IT and culture technology. We conducted a case study on maker education(VR production project, electronic publishing, beads craft, leather craft, IoT) which was held from July 8 to August 30, 2017 five times. We conducted interviews with five preliminary makers who participated in all the courses of the education, and five instructors who acted as professional makers with pre- developed questionnaires. The results of the study were derived by applying the Thematic Analysis method after opening the contents of the interview. Based on the results of the study, we could suggest characteristics of Korean makers and future direction of maker education.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.851-856
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• 2018

In this study, we analyze the characteristics of wireless power transfer(WPT) based on magnetic resonance in an underwater environment and propose an equivalent model suitable for underwater WPT. The proposed underwater WPT equivalent model is constructed by expanding the free-space WPT T-model reflecting characteristics change according to media. Considering the water salinity, we propose a method to extract the parameters of the proposed model based on the S parameters. To verify the proposed model, a 6.78-MHz underwater WPT system was constructed and compared with the predicted power transfer efficiency of the model. As a result, it was confirmed that the proposed model predicts the variation of characteristics with an average error of less than 3 %.

• Journal of Broadcast Engineering
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• v.23 no.6
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• pp.876-885
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• 2018

Although e-sports broadcasting market based on VR(Virtual Reality) is growing in these days, technology development for securing market competitiveness is quite inadequate in Korea. Global companies such as SLIVER and Facebook already developed and are trying to commercialize 360 VR broadcasting technology which is able to broadcast e-sports in 4K 30FPS VR video. However, 2D video is too poor to use for 360 VR video in that it brings less immersive experience and dizziness and has low resolution in the scene. this paper, we not only proposed and implemented virtual camera technology which is able to capture in-game space as 360 video with 4K 3D by 60FPS for e-sports VR broadcasting but also verified feasibleness of obtaining stereo 360 video up to 4K/60FPS by conducting experiment after setting up virtual camera in sample games from game engine and commercial games.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.807-808
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• 2016

With the recent rise in nuclear families and single-member families, there is a need for the kind of home management unaffected by neither space nor time. Moreover, electronic devices in and around the home need to be managed efficiently and prevented from overheating, and there is an increasing risk of fire, theft, and leak of personal data with these devices, which is leading to an increase in the economic costs. Accordingly, there is a growing need for an efficient and secure smart home management system. This paper proposes a home management system that uses smart devices. This system has addressed the shortcomings of a conventional Internet-based home network. Furthermore, it communicates with IoT-enabled devices and features intelligent information home appliances that are isolated from personally identifiable information and which are secure against advanced persistent threats, a type of cyber-attack.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.247-249
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• 2016

Corporation, local government and government office provide useful information. Advertisement service is getting various manner. Typical example is electronic display, TV-advertisement and internet or mobile advertisement service. In this paper, I'm study about Taxi-advertisement service still. A similar case is bus or subway advertisement from display. But, Taxi have been only lapping advertisement. Because, Taxi get space restraints. Broadly speaking, Person using Gyeonggi-do to Soeul or Incheon to Soeul is 423million people. On a national basis, it's very amazing figure. However It's just so many person showing one advertisement. So people have no interest in advertisement. So I develop new advertisement system through taxi in the whole country. 254,823 car have passenger personal information and showing people needing advertisement. Also this system get geographical information. This system have high advertisement effect.

• Journal of Power Electronics
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• v.19 no.1
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• pp.190-200
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• 2019

The flyback converter, which can be regarded as a nonlinear time-varying system, has complex dynamics and nonlinear behaviors. These phenomena can affect the stability of the converter. To simplify the modeling process and retain the information of the output capacitor branch, a special sampled-data model of a peak current-mode (PCM) controlled flyback converter is established in this paper. Based on this, its dynamic behaviors are analyzed, which provides guidance for designing the circuit parameters of the converter. With the critical stability boundary equation derived by a Jacobian matrix, the stable operation range with a varied output capacitor, proportional coefficient of error the amplifier, input voltage, reference voltage and slope of the compensation ramp of a PCM controlled flyback converter are investigated in detail. Research results show that the duty ratio should be less than 0.5 for a PCM controlled flyback converter without ramp compensation to operate in a stable state. The stability regions in the parameter space between the output capacitor and the proportional coefficient of the error amplifier are enlarged by increasing the input voltage or by decreasing the reference voltage. Furthermore, the ramp compensation also can extend to the stable region. Finally, time-domain simulations and experimental results are presented to verify the theoretical analysis results.

• The Journal of the Acoustical Society of Korea
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• v.38 no.4
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• pp.467-475
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• 2019

A high-intensity ultrasound wave generates acoustic streaming and acoustic radiation forces when propagating through a medium. An acoustic radiation force generated in a three-dimensional space can produce a solid tactile sensation, delivering spatial information directly to the human skin. We placed 154 ultrasound transmit elements with a frequency of 40 kHz on a concave circular dish, and generated an acoustic radiation force at the focal point by transmitting the ultrasound wave. To feel the tactile sensation better, the transmit elements were excited by sine waves whose amplitude was modulated by a 60 Hz square wave. As an application of ultrasonic tactile sensing, a region where tactile sense is formed in the air is used as an indicator for the position of the hand. We confirmed the utility of ultrasonic tactile feedback by implementing a system that provides the number of fingers to a machine by receiving the shape of the hand at the focal point where the tactile sense is detected.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.2
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• pp.142-149
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• 2019

The coils to transmit the electric energy are necessary to charge an electric vehicle wirelessly. There are several types of coils, from basic circular coils to DD-type coils for enhancing the coupling effect between two coils. However, DD-type coils with a good coupling effect between coils have a disadvantage in use because of the structure complexity of the power conversion device of transmitting and receiving side. In this paper, we propose a method to calculate the inductance value and to design the size of the spiral inductor which is convenient to fabricate when the power is transmitted wirelessly by using two coils in free space. Since the bifurcation phenomenon occurs when the XLm value is similar to the load resistance value in the resonator the XLm value was selected to be equal to the minimum load resistance value to minimize this phenomenon, and the inductance value required for the resonator was calculated. In order to realize the calculated inductance value by the spiral inductor, the relationship between the inductance value and the size, the number of turns, the total coil length of a spiral inductor was investigated. In addition, the change of coupling coefficient k according to the horizontal separation of two coils was examined and an appropriate inductor was selected.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.1
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• pp.1-7
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• 2020

Fuzzy clustering, represented by FCM(Fuzzy C-Means), is a simple and efficient clustering method. However, the object function in FCM makes clusters affect clustering results proportional to the density of clusters, which can distort clustering results due to density difference between clusters. One method to alleviate this density problem is EDI-FCM(Extended Density-Independent FCM), which adds additional terms to the objective function of FCM to compensate for the density difference. In this paper, proposed is an enhanced EDI-FCM using regularization, Regularized EDI-FCM. Regularization is commonly used to make a solution space smooth and an algorithm noise insensitive. In clustering, regularization can reduce the effect of a high-density cluster on clustering results. The proposed method converges quickly and accurately to real centers when compared with FCM and EDI-FCM, which can be verified with experimental results.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.6
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• pp.57-68
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• 2004

Recently, Radio Frequency Identification (RFID) systems stands in the spotlight of industry as a common and useful tool in manufacturing, supply chain management (SCM) and stock management. In the near future, low-cost RFID Electronic Product Code; (EPC) or smart-labels may be a practical replacement for optical barcodes on consumer items. However, manufacturing cheap and small RFID tags, and developing secure RFID authentication Protocols are problems which need to be solved. In spite of advances in semiconductor technology, computation and storage ability of the tag are so limited that it is difficult and too expensive to apply existing crypto-systems to RFID tags. Thus it is necessary to create a new protocol which would require less storage space and lower computation costs and that is secure in the RFID system's environments. In this paper, we propose a RFID authentication protocol that is secure against location tracking and spoofing attacks. Our protocol can be used as a practical solution for privacy protection because it requires less computations in database than the previous RFID authentication protocol.