• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.852-857
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• 2010

In this paper, we proposed and demonstrated an indoor visible-light communication system using an array of light-emitting diodes (LEDs). The main idea is based on that the LEDs can be used not only for lighting but also for free-space optical communications. Because LEDs offer advantageous properties such as high brightness, reliability, lower power consumption and long lifetime, the indoor visible-light communication systems are going to provide high quality of service by the high radiation power of the LED lighting. Prototype of simplex channel for audio and the full-duplex channel for text message were developed. Results indicates the viability of creating inexpensive free-space optical communication transceivers that might be embedded in commercial light products to supports indoor wireless networking.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.445-450
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• 2018

AIS is the most important navigation equipment for the identification of other ships, etc. However, the AIS overload problem has been raised recently due to an increase in AIS equipped vessels. The government is planning to introduce the wireless LTE network at 100 km offshore as part of the SMART-Navigation project. Continuous development and dissemination of the services available through such platforms will be necessary to achieve major goals such as marine accident prevention and environmental protection. In this study, we applied a WAVE communication system, which could be the basis for the development of such services. As a result, reliable data transmission was confirmed for a range of communication of approx. 5 miles, although the service was limited to 1 km in road traffic. Therefore, it is expected that WAVE communication technology will be used to prevent marine accidents through such efforts as collision avoidance and the transfer of marine safety information between ships.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.83-84
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• 2006

크랭크 샤프트 디플렉션 측정은 선박엔진의 조립공정에 있어, 크랭크 샤프트를 조립 시 1회전의 상태에서 크랭크 스루 간의 디플렉션 상대값의 변화를 확인하는 것이다. 이를 통하여 크랭크 샤프트가 정상 조립되었는지 확인할 수 있다. 기 개발 완료한 구형 무선 크랭크 샤프트 디플렉션 측정장치(상품명 : Measutal)는 측정장치의 길이로 인해 선박용 엔진 중 저속 엔진에만 적용 가능하였다. 하지만 중속엔진의 경우 공간이 협소하여 크랭크 샤프트 디플렉션 측정이 어려우며, 이는 폭정 오차를 수반하게 된다. 본 논문은 상기 문제를 해결하기 위해 중속에도 적용 가능한 신 모델의 개발에 관한 것이다. 또한 개발된 신 모델은 소비자의 요구를 만족하기 위해 구 모델에 비하여 밧데리 지속시간 향상되었고 무선 통신 거리가 확대되었다.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.2
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• pp.166-171
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• 2015

Recently, the international standard RS-422 serial communication, which was primarily designed for the communications between micro-controllers, has been used as a communication method on the ship. However, as the NMEA (National Marine Electronics Association) 2000 standardization progresses recently, a high-speed Ethernet-based communication environment is expected to be an alternative communication method instead of the RS-422 gradually. In addition, the ship's main instrumentation equipment with versatility and convenience is implemented to control devices as monitoring and controlling tools. This paper describes an implementation of wireless ultrasonic anemometer and anemoscope data processing and logger system using PC network, where the control processing equipment such as a separate operational console, data-logger, and indicator is required for the system. For these, the related element technologies to implement ultrasonic anemometer and anemoscope data processing system are expressed as a functional modules, and the NMEA 2000 standard certified data-logger system is implemented without the separate operational console.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.3
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• pp.326-332
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• 2019

Recently, the deep learning technology has gained lots of attention which leads to its application to various fields. Especially, there are recent attempts to overcome the limit of wireless communications systems through the use of the deep learning. In this paper, we have verified the performance of deep learning based transmit power control scheme. Unlike previous transmit power control schemes where the optimal transmit power is derived by solving the optimization problem explicitly, in the deep learning based transmit power control, the general solver for the optimization problem is derived through the deep neural network (DNN). Especially, by using the spectral efficiency as the loss function of DNN, the training can be performed without needing labels. Through simulation based on Tensorflow, we confirm that the transmit power control based on deep learning can achieve the optimal performance while reducing the computational complexity by 1/200.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.5
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• pp.567-574
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• 2014

In this paper, a VHF antenna with monopole structure is designed and fabricated for marine wireless communication applications. The proposed antenna is based on a monopole design, and composed of circular ring and meander structure for VHF operation which cover VHF frequency bands. To obtain the optimized parameters, we used the simulator, Ansoft's High Frequency Structure Simulator(HFSS) and found the parameters that greatly effect antenna characteristics. Using the obtained parameters, the antenna is fabricated. The experiment results demonstrated that the proposed antenna satisfied the -10 dB impedance bandwidth requirement while covering the VHF bands. And measured characteristics of gain and radiation patterns are obtained for operating bands.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.2
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• pp.151-158
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• 2019

Wireless communication technology (WAVE) for vehicles, which is the core technology behind the next-generation intelligent transport system (C-ITS), is used to deliver information about vehicles to prevent traffic accidents and traffic situations that may arise between vehicles and infrastructure. Similar traffic issues often arise in marine scenarios. Currently, AIS is being used as a means of transmitting information such as the status of relative vessels, but research is being carried out to solve problems with AIS such as overloading by applying wireless communication technology for vehicles to the sea. In this study, a collision warning system suitable for small-sized vessels was developed based on the marine application of WAVE for vehicles verified through prior research, and the adequacy of this collision warning system was reviewed through a practical test. It is expected that this system will contribute greatly to future e-Navigation applications or self-driving ships as well as to preventing marine accidents.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.153-161
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• 2008

Recently, the research and development of the fish cage in open sea from domestic is active and it is almost complement with commercial scale test on 'seogwipo'. But domestic technology is not sufficient of management RMS(Remote Monitoring System) with advanced country, so it is difficult to maintenance and monitor fish cage in open sea. This paper introduces a fish cage environmental monitoring system for measuring pH, DO and temperature. A signal is treated with DAU(Data Acquisition Unit) by a wireless communication method and transfers data to host computer for data processing. These data are graphically shown on the monitor with LabVIEW program and logged on the data processing system in the form of file.

• Journal of Fisheries and Marine Sciences Education
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• v.16 no.2
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• pp.163-170
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• 2004

The rapid exchanges of mobile computing environment and development of wireless communication are providing many effects for learning activity of students. Recently, PDA system developers which are studying memory capacity, communication speed and size of screen support techniques to be capable of learning from students in the wireless or moving environment. In this viewpoints, this paper has a purpose to design multimedia learning system to be able to do with sound lecture contents. The implemented system largely consists of two parts which have the teacher module and students module. The one manages learning progress of students, class management, bulletin board and etc. The other is capable of using studying and bulletin functions. The main idea of this research is focus to upgrade the effect of learning without almost treating the existing studies, which can be listening sound lecture and also seeing text and image at the same time.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.8
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• pp.1111-1116
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• 2012

At present, indoor optical wireless communications using LED lightings has been widely studied. The combination of this technology to the low voltage powerline grid installed in each home makes an efficient method for fulfilling the premise of broadband access for home networking. In this paper, white LEDs were used for both illumination and remote-control, so that information can be broadcast within a room for control the optical wireless systems. We implemented a model car to evaluate the performance of optical wireless remote-control. The requirement for levels of illumination suitable for communication were investigated and applied to design the test-bed. In spite of limitation of line-of-sight communications, it will open up new applications to the optical wireless remote control system in an electromagnetic interference region.