• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.102-104
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• 2011

최근 비디오 스트리밍과 대화형 비디오 서비스 등과 같은 광대역 멀티미디어 서비스를 지원하기 위하여 Wimax와 같은 4G 무선네트워크 시스템 기술이 발전해 왔다. 4G 무선네트워크의 OFDM(Orthogonal Frequency Division Multiplexing)과 MIMO(multi Input Multi Output)은 사용자들에게 매우 유연한 QoS(Quality of Service) 서비스를 제공해 줄 수 있다.[1] 이 논문에서는 다양한 네트워크 상황에서 멀티캐스트 그룹에게 효율적인 방법으로 통신 자원을 할당하기 위해 OFDM 방법을 사용 하였다. 이에 본 논문에서는 한 셀(cell) 내의 서로 다른 멀티캐스트의 그룹의 다른 SNR(Signal to noise Ratio)의 사용자 분포에 따른 적응적인 scalable 비디오 멀티캐스트 방식을 제안한다. 더 나은 수신율을 가진 사용자는 최적의 MCS(Modulation and Coding Scheme) 할당을 통해 서로 다른 화질의 scalable 비디오 계층 중 높은 해상도의 비디오를 받을 수 있다. 논문에서는 전체 전송률을 최적화 하는 대신 전송받은 전체 비디오의 평균 화질을 최적화하는 방법을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.6
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• pp.681-688
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• 2016

Several VHF bands for the use in analog communications has been changed to those for the use in new maritime digital communications by WRC-12. ITU-R M. 1842-1 has been also standardized, recommending the characteristics of maritime digital communication systems. In addition, a Shipborne Ad-hoc Network (SANET) has been introduced by IMO in order to provide ships, which cannot be connected to a shore directly, with maritime digital data exchange services with the help of ad-hoc communication. In this paper, several functionalities of the SANET, including channel access, route determination to a shore, and data exchange, are verified via sea trials. It is expected that the SANET can be applicable to collecting and analyzing maritime information, facilitating the entry and departure of vessels, and the communication infrastructure of e-navigation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.53-60
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• 2017

This paper is to design and implement the drone that supports a wideband multimedia communication and a long-range to save people in maritime. The drone is an Unnamed Aerial Vehicle (UAV) that is controlled by a radio wave not by people boarding the machine. We use the drone to respond quickly to the boating accident. To develop a smart drone for the high speed seamless video streaming in a long-range maritime, a necessary techniques are hardware design techniques that design structure of a drone, controlling techniques that operate a drone and communication techniques that control a drone in a long distance. In this paper, the limitations and techniques to design and implement the structure of drone supporting wideband multimedia communication for long-range maritime are explained. By expanding this communication drone network, it is aimed at improving utility of a drone.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1808-1818
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• 2015

Recently, the wind power has experienced great attentions and growths among many renewable energy sources. To increase the power generation performance and economic feasibility, the size of wind turbine (WT) is getting bigger and most of wind power plants are being constructed on offshore. Therefore, the maintenance cost is relatively high because boats or helicopters are needed operators to reach the WT. In order to combat this kind of problem, remote monitoring and control system for the WT is needed. In this paper, the small-scale WT monitoring and control system is implemented using wireless sensor network technologies. To do this, sensor devices are installed to measure and send the WT status and control device is installed to receive control message for specific operation. The WT is managed by control center through graphic user interface (GUI) based monitoring and control software. Also, smart device based web-program is implemented to make the remote monitoring of the WT possible even though operators are not in control room.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.177-180
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• 2008

최근 유/무선 통신망과 접속 기술의 발달로 사용자들은 다양한 네트워크로의 접근이 가능하게 되었다. 하지만 이러한 여러 종류의 접속 기술은 접속 기술간 서비스 이동에 따른 이동성 보장이 서로 독립적이기 때문에 핸드오버 시 부가적인 지연이 발생하는 문제가 있다. 또한 다른 접속 서비스로의 비디오 전송 시 QoS 보장이 어려운 문제점이 있다. 따라서 본 논문에서 IEEE 802.21 Media Independent Handover 정보 서비스를 이용하여 네트워크 접속망에서 스케일러블 비디오 코딩 전송 방법을 제안한다. 이는 MIH Function에서 각 단말기에 대한 데이터 전송률과 QoS 정보를 MIH 정보 서버로부터 얻어 비디오 스케일링 레이어를 결정한다. 이렇게 결정된 스케일링 레이어를 이용하여 스케일러블 비디오 코딩을 수행한 후, 각각의 단말기에게 비디오를 전송하게 된다. 이러한 새로운 스케일러블 비디오 전송 모델은 서로 다른 여러 종류의 해상도, 화질, 프레임 전송률을 갖는 영상을 다양한 네트워크의 다양한 디바이스로 적응적인 비디오 전송이 가능하다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2008.04a
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• pp.251-254
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• 2008

유비쿼터스 네트워크의 실현을 위한 4세대 통신방식의 유력한 후보로 부상하는 OFDM (Orthogonal Frequency Division Multiplexing) 통신방식이 육상에 주목받고 있으며, 고속 데이터 전송을 위한 무선랜의 표준기술로 확정되어 있다. 해상 통신의 경우에서도 OFDM 통신방식은 단파대역을 이용한 데이터 전송방식으로 제안되고 있으며, ITU (International Telecommunication Union)는 해상통신에서 32-point FFT를 사용하도록 권고하고 있다. 해상 통신에서는 해양사고 및 조난 시에도 통신이 이루어져야 하는 한계상황을 고려하면, OFDM 통신방식의 중요 디바이스인 FFT는 저전력으로 동작되어야 한다. 따라서 본 논문에서는 OFDM 방식의 중요 디바이스인 32-point FFT를 저전력으로 동작시키기 위해 radix-2와 radix-4를 이용하여 저전력 32-point FFT 알고리즘을 제안한다. 최적화된 설계로 32-point FFT를 저전력 동작이 가능하도록 설계하였으며, 제안한 알고리즘은 VHDL로 구현하고 FPGA Spartan3 board에 장착하여 Matlab의 이론값과 비교, 검증하였다. 제안된 32-point FFT는 해상통신에서의 OFDM 적용을 위한 선도기술로 유용할 것이다.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.5
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• pp.667-674
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• 2011

Data networks at sea will be overlapped networks with not only traditional carriers such as RF, satellites but also BWA like wireless LAN, WiBro, and WCDMA in near future. In this paper, an overlapped MANET model for data networks at sea, and a routing protocol (OMH-MW) selecting optimal transmission medium for each hop in routes are proposed. OMH-MW measures the optimality of each medium regarding the transmission characteristics of each application and those of the medium in together. The most suitable medium to each link is selected as the link in routes. Performances are compared with those of the MWR (Max-Win based Routing protocol searching optimal routes with only one medium).

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.21-27
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• 2023

As a means of helping ships navigate safely, navigational aids in operation in the maritime envirionment require periodic management, and due to the nature of the environment, it is difficult to visually check the exact state. As a result, the smart navigation aid system, which improves route safety and operational efficiency, utillizes expertise including sensors, communications, and information technology, unlike general route markings. The communication environment of the smart navigation aid system, which aims to ensure the safety of the navigators operating the ship and the safety of the ship, uses a wireless communication network in accordance with the marine environment. The ship collects the information necessary for the maritime environment on the land and operates. In this process, there is a need to consider the wireless communication security guideline. Basically, based on IHO S-100 a standard for facilitating data exchange and SECOM, which provides an interface for safe communication. This paper research a security system for safe communication in a maritime environment. The security system for the basic interface based on the document was presented, and there were some vulnerabillties to data exchange due to the wireless communication characteristics of the maritime environment, and the user authetication part was added considering the vulnerability that unauthorized users can access the service.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.10
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• pp.1-6
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• 2007

Wireless Self-Powered Temperature Sensor for UHF Sensor Tags which are basic device for construction of ubiquitous sensor network is proposed. The key parameters of the target specification are resolution of $0.1\;^{\circ}C$ per output bit, below 1.5 V of operating voltage and below 5 uW of power consumption during sensing operation. Temperature sensor circuit consists of PTAT current generator, band gap reference circuit generating both reference voltage and current, Sigma-Delta Converter, and Digital Counter. Simulated maximum resolution was $0.23\;^{\circ}C/bit$ in 11-bit output. The proposed temperature sensor was fabricated by using a 0.25 m CMOS process. The chip area is $0.32\;{\times}\;0.22\;mm$ and the operating frequency is 2 MHz. Measured resolution from fabricated temperature sensor was $4\;^{\circ}C/bit$ in 8-bit output for the temperature range from $10^{\circ}C$ to $80^{\circ}C$.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.4
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• pp.353-361
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• 2017

As ship-based tourism increases, safe sailing and management are necessary to prevent maritime accidents. Because external rescue support cannot arrive rapidly in the case of ship-related accidents, the initial response is very important for damage minimization. Further, for secondary damage prevention, it is necessary to accurately determine passenger positions. In this paper, considering the characteristics of a ship, the enhanced-Zigbee(e-Zigbee) position determination technology (PDT) is applied, which improved upon the Zigbee PDT by having advantages such as low power consumption and smaller size. According to user needs, a low-cost and high-precision passenger positioning tag and access point(AP) is provided. A ship testbed that yields improved positioning accuracy based on a performance evaluation is constructed.