• Smart Media Journal
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• v.12 no.3
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• pp.49-59
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• 2023

Optical Camera Communication (OCC), known as the next-generation wireless communication technology, is currently under extensive research. The performance of OCC technology is affected by the communication environment, and various strategies are being studied to improve it. Among them, the most prominent method is applying convolutional neural networks (CNN) to the receiver of OCC using deep learning technology. However, in most studies, CNN is simply used to detect the transmitter. In this paper, we experiment with applying the convolutional neural network not only for transmitter detection but also for the Rx demodulation system. We hypothesize that, since the data images of the OCC system are relatively simple to classify compared to other image datasets, high accuracy results will appear in most CNN models. To prove this hypothesis, we designed and implemented an OCC system to collect data and applied it to 12 different CNN models for experimentation. The experimental results showed that not only high-performance CNN models with many parameters but also lightweight CNN models achieved an accuracy of over 99%. Through this, we confirmed the feasibility of applying the OCC system in real-time on mobile devices such as smartphones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.8
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• pp.700-705
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• 2013

If LED lighting is to be used in home networking, a home gateway and power line communication are needed in delivering data. In addition, an appropriate multiple access scheme reflecting LED's property is required. In this paper, a home networking system that can serve wide in-building area by integrating PLC and VLC, is proposed and implemented, then its performance is measured. A binary CDMA is used in the multiple access since this scheme is good for nonlinear device like LED, while infrared is used in the upstream transmission.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1646-1654
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• 2015

In this paper, a single-switch ZVZCS quasi-resonant CLL isolated DC-DC converter for driving a low-power (less than 100 W) 32'' LED backlighting liquid crystal display television (LCD TV) is proposed. The proposed converter exhibits both forward and flyback operational characteristics. All semiconductors are activated and deactivated under the soft switching conditions during the switching transition without additional active devices. The switching frequency varies less than about 10 kHz for load variations, leading to minimizing the efficiency reduction under light load. Furthermore, the low di/dt and dv/dt by soft switching enhance the electromagnetic interference (EMI) performance above 1 MHz. A theoretical analysis is described in detail, and a 72-W prototype converter verifies the validity of the analysis.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.6
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• pp.408-413
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• 2015

Road lighting has emerged in importance as an essential system to secure safety and visibility for drivers and pedestrians. According to the Road Lighting Standards (KS A 3701), the luminance uniformity (U0) should be 0.4, the luminance uniformity for lanes (UI) should be 0.5, and a threshold increment (TI) of 10% should be satisfied. In this study, we conducted simulations using the Relux program in which the secondary optical lens was applied to a 21 W engine. Ten LED engines were installed on a two-way four-lane road, and the simulation result satisfied the requirements with U0 0.47, UI 0.63 and TI 8%. The U0, UI, and TI were compared with the angle of the LED streetlight varied in the range of $9^{\circ}{\sim}15^{\circ}$ with $0.5^{\circ}$ intervals. The range was selected as ${\pm}25%$ of the standard inclination angle of $12^{\circ}$ according to the Road Lighting Standard. The U0 was high and the UI and TI were low when the tilting angle was in the range of $9.5^{\circ}{\sim}10.5^{\circ}$. Consequently, an optimum-design of lighting distribution was obtained for the concrete two-way four-lane road when the inclination angle was $9^{\circ}$.

• The Journal of the Korea Contents Association
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• v.20 no.2
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• pp.572-580
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• 2020

Recently released AI speakers show a pattern of interacting with the user by mainly with voice and simultaneously displaying simple and formal visual feedback through status LED light. This is due to the limitations of the product characteristics of the speaker, which makes it difficult to interact variously, and even such visual feedback is not standardized for each product, and thus does not give a consistent user experience. By maximizing the visual elements that can be expressed through color and abstract movement to assist voice feedback, the product can provide the user with an extended experience that includes not only functional satisfaction but also emotional satisfaction. In this study, after analyzing the interaction methods of the existing AI speakers, we examined the theory of color communication in order to expand the visual feedback effect, and examined the meaning and expression technique of Color Field Painting, an art genre that maximizes the emotional experience by using only color. Through this, the AI speaker's visual communication function was expanded by designing a way to feedback communication status using LED light.

• Korean journal of communication and information
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• v.57
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• pp.137-159
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• 2012

This is a dissertation about the state and cable television industry relationship during the early days of Kim Dae-Jung administration(1998.2-2000.1) in Korea. This study adopted historical approach and methodology of archival research. Offe's state theories of reproduction of late capitalism and the concept of Korean patriarchal state-led capitalism were suggested in this paper. Offe argued that the goal of the late capitalist state is successful capital accumulation and democratic legitimation with bureaucratic rationalization. For this purpose, the state intervenes market structuring by various plans and national policies. The Kim Dae-Jung administration reorganized cable television market with neo-liberalistic strategies and corporatist forms of policy-making. The government negotiated capitalists and civil society for managing capitalistic economy and cable television market in a horizontal relationship. Successful consequences of the market growth resulted in generating mass loyalty. The former administrations to the contrary, invisibly arranged state-led capitalism was an only alternative to the Kim Dae-Jung administration. The Korean state-led capitalism evolved gradually into different forms.

• Journal of IKEEE
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• v.17 no.3
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• pp.267-274
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• 2013

This paper presents a design of LLC resonant converter IC for LED backlight unit based on PFM/PWM dual-mode feedback. Dual output LLC resonant architecture with a single inductor is proposed, where the master output is controlled by the PFM and slave output is controlled by the PWM. To regulate the master output PFM is used as feedback to control the frequency of the power switch. On the other hand, PWM feedback is used to control the pulse width of the power switch and to regulate the slave output. This chip is fabricated in 0.35um 2P3M BC(Bipolar-CMOS-DMOS) Process and the die area is $2.3mm{\times}2.2mm$. Current consumptions is 26mA from 5V supply.

• 한국ITS학회:학술대회논문집
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• 2010.05a
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• pp.141-144
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• 2010

• The Journal of Korea Robotics Society
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• v.11 no.1
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• pp.19-25
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• 2016

In this paper, we propose a new method for improving the accuracy of localizing a robot to find the position of a robot in indoor environment. The proposed method uses visible light for indoor localization with a reference receiver to estimate optical power of individual LED in order to reduce localization errors which are caused by aging of LED components and different optical power for each individual LED, etc. We evaluate the performance of the proposed method by comparing it with the performance of traditional model. In several simulations, probability density functions and cumulative distribution functions of localization errors are also obtained. Results indicate that the proposed method is able to reduce localization errors from 7.3 cm to 1.6 cm with a precision of 95%.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.161-167
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• 2015

The performance of high power LEDs highly depends on the junction temperature. Operating at high junction temperature causes elevation of the overall thermal resistance which causes degradation of light intensity and lifetime. Thus, appropriate thermal management is critical for LED packaging. The main goal of this research is to improve thermal resistance by optimizing and comparing nano-pore silicon-based thermal substrate to insulated metal substrate and direct bonded copper thermal substrate. The thermal resistance of the packages are evaluated using computation fluid dynamic approach for 1 W single chip LED module.