• 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.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.998-1000
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• 2008

센서 노드 운영체제는 응용 프로그래머의 개발 지원 및 체계적인 센서 관리를 위하여 센서 투명성을 지원해야 한다. 하지만 기존 센서 노드 운영체제들은 센서투명성을 지원하지 못한다. 센서 디바이스 드라이버를 응용이 직접 작성해야 하며 다양한 센서를 위한 공통 인터페이스를 제공하지 못한다. 본 논문에서는 센서 투명성을 지원하는 센서 디바이스 매니저를 제안한다. ETRI에서 개발한 Nano-Q+에서 센서 디바이스 매니저 기능을 구현하기 위하여 센서노드 플랫폼, 응용 API, 디바이스 매니저, HAL을 설계하고 구현하였다. 또한, 기존 Nano-Q+와 성능을 비교하고 평가하였다. 센서디바이스 매니저를 구현하여도 처리 속도 및 용량에 대한 성능 저하가 없음을 확인하였다.

• Journal of Convergence for Information Technology
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• v.10 no.2
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• pp.96-101
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• 2020

In micro-sized light emitting diodes, which are increasingly attentions as the light sources of displays and semiconductor lighting, increasing the amount of light and improving the luminous efficiency are very important and various development directions and methods have been proposed. In this study, the design of 3-dimensional nano structures through nano frame formation and the application of a nano pattern and a reactive etching method were proposed. And it will also be discussed that nano pillar arrays with nano cavities having improved verticality can be applied to semiconductor light sources through the development of nano frame structures.

• International journal of advanced smart convergence
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• v.5 no.3
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• pp.66-71
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• 2016

Smart building gate security control system using smartphone integrated with near field communication (NFC) has become part of daily life usage these days. The technology change in replacing RF NFC device using visible light communication technology based approach growing faster in recent days. This paper propose a design and development of gate security control system using color code based user authentication ID generation as part of an intelligent access control system to control automatic door open and close. In this approach gate security access control use the recent visible light communication technology trends to transfer the user specific authentication code to door access control system using color code on smartphone screen. Using a camera in the door access control system (ACS), color codes on smartphone screens are detected and matched to the database of authenticated user to open the door automatically in gate security system. We measure the visual light communication technology efficiency as a part of the research and the experiments have revealed that more than 95% users authenticated correctly at the suggested experiment environment on gate security control system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.723-743
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• 2016

Indoor positioning is considered an enabler for a variety of applications, the demand for an indoor positioning service has also been accelerated. That is because that people spend most of their time indoor environment. Meanwhile, the smartphone integrated powerful camera is an efficient platform for navigation and positioning. However, for high accuracy indoor positioning by using a smartphone, there are two constraints that includes: (1) limited computational and memory resources of smartphone; (2) users' moving in large buildings. To address those issues, this paper uses the TC-OFDM for calculating the coarse positioning information includes horizontal and altitude information for assisting smartphone camera-based positioning. Moreover, a unified representation model of image features under variety of scenarios whose name is FAST-SURF is established for computing the fine location. Finally, an optimization marginalized particle filter is proposed for fusing the positioning information from TC-OFDM and images. The experimental result shows that the wide location detection accuracy is 0.823 m (1σ) at horizontal and 0.5 m at vertical. Comparing to the WiFi-based and ibeacon-based positioning methods, our method is powerful while being easy to be deployed and optimized.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.2
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• pp.126-130
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• 2015

In this study, some materials are organized and experimented with variables to obtain the optimum mix proportion for the mechanical property of halogen free flame resistance compound with varying addition of nano clay. Tensile strength, density and stiffness are tested in the room temperature. In this study, unlike existing layered structure, nano clay with tabular structure is used and sufficient stiffness, strength, thermal stability and gas block capability can be achieved with small amount of addition. Tensile strength and elongation test show high rupture strength only in specimens with compatibilizing agents while density test shows average measurement in all the specimens except T-9. It was confirmed that the measurement value according to the additives in compatibilizing agent or in nano clay of hardness test represents similarly.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1712-1719
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• 2015

In recent days, there was a significant development on the electrical, thermal, mechanical, physical, chemical, magnetic and optical properties of the polyamide enamel, varnish and other insulating materials by the addition of nano fillers to it. Enamel was used in High Voltage Apparatuses used in Medical Electronics as insulation. Insulating materials determine the life time of the electrical apparatuses. The life time of the insulating materials was improved by the addition of nano fillers to it. Hence the life time of the electrical apparatuses was improved by the mixing of nano fillers to the enamel. In this research, the basic dielectric properties of the enamel and enamel mixed with nano composites of silica and alumina were analyzed and compared with each other. The addition of nano fillers has improved the quality factor and capacitance of the enamel. It was also observed that the addition of nano fillers has reduced the dissipation factor and dielectric losses of the enamel. Heat produced by the dielectric losses was also reduced by adding nano fillers to it.

• Journal of Korea Multimedia Society
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• v.19 no.9
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• pp.1690-1697
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• 2016

In a beacon-enabled Zigbee network, the slotted CSMA/CA mechanism based on the super frame structure fairly provides communication chance for each node and makes a reasonable usage of the available energy. In the case of wireless nano sensors that are implanted into the target human body area for detecting disease symptoms or virus, such a nano-network requires a similar type of channel sharing and transmission of short length event-driven data. In this paper, for nano-network's in-body applications, we aim to design conceptually a new super frame derived from the existing beacon-enabled Zigbee MAC protocol. And we analyze the efficiency of the proposed super frame in the aspect of practical deployment.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1751-1752
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• 2008

The heterodyne laser interferometer has a nano-meter scale resolution. However, the unwanted nonlinearity error caused from frequency-mixing limits the ultra-precise resolution. In this paper, we propose a recursive WLS algorithm to improve the resolution of heterodyne laser interferometer. Some experimental results show an effectiveness of the recursive WLS algorithm in nano-meter scale resolution.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.153-153
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• 2018

In this paper, we have represented basic experiment results for the application of electric vehicle powerline communication using an induction type coupler. The coupler was fabricated using nano-crystalline alloy and it was applied to the charging system of electric vehicles to measure the communication performance. Experimental results showed a channel bandwidth over 48 Mbps.