• Journal of information and communication convergence engineering
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• v.11 no.3
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• pp.167-172
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• 2013

Recently, mobile communication systems are suffering from exponentially increasing data traffic. As a promising solution to the increase in data traffic, a coordinated multi-point transmission and reception (CoMP) scheme has been proposed. Although a great deal of research has been done on this new technology, the performance of mobile communication systems with CoMP has not been evaluated properly in a typical indoor environment. To address this, we have developed a system-level simulator and evaluated the performance of mobile communication systems with CoMP. Unlike previous works, we have used an actual antenna pattern in our simulator and link-level results are properly taken into account through link-level abstraction. By using a system-level simulator, we have evaluated the performance of mobile communication systems with CoMP in an indoor environment and found that unlike an outdoor cellular environment, CoMP may not improve the performance of overall mobile communication systems in an indoor environment.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.6
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• pp.490-500
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• 2011

The paradigm that ships are navigated by means of analog navigation devices and caption's experiences is shifted to that ships can be navigated by digital and autonomous navigation systems due to the rapid development of electronics and communication technologies. Hence, all systems deployed in a ship are automated and integrated since corresponding ship systems are not individually operated but integrated and managed under common operating system. In this paper, we overview recent research projects targeted for digitally integrated ships (referred to as digital ships), outline IEC 61162 series, specifying digital interface standards for digital ships, and finally present several issues for further improvement of the IEC 61162 series. In addition, we broadly categorize digital ships into three systems consisting of multiple sub-systems, including a navigation system, a power system, and a automation system in the aspect of operation and function. Corresponding interfacing range and method, as well as interface specification and data types of one system in a digital ship are also described according to sub-systems, respectively.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.6-8
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• 2009

In this paper. we propose receiver algorithms for VHF(Very High Frequency) digital link mode-2(VDL Mode-2) systems. Unlike conventional digital communication systems using the root raised cosine filter as a transmit and receive filter, raised cosine filter is used as a transmit filter in VDL Mode-2 systems. Hence, it is crucial to design and implement the optimum lowpass receive filter by considering the amount of inter-symbol interference and noise performance. On the other hand, due to the short preamble pattern, it is crucial to develop an efficient packet detection algorithm for reliable communication link. In this paper, we design the optimum receive filter and packet detection algorithm and evaluate the performance of receiver adopting the proposed receive filter and packet detection algorithm.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.142-146
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• 2012

Today, the demand for high-speed data communication and mobile communication has exploded. Thus, there is a growing need for optical communication systems that convert large volumes of data to optical signals and that accommodate and transmit the signals across long distances. Digital optical communication with these characteristics consists of a master unit (MU) and a slave unit (SU). However, the digital optical units that are currently commercialized or being developed transmit data without compression. Thus, digital optical communication using these units is restricted by the quantity of optical frames when adding diversity or operating with various combinations of CDMA, WCDMA, WiBro, GSM, LTE, and other mobile communication technologies. This paper suggests the application of a data compression algorithm to a digital signal processor (DSP) chip as a field programmable gate array (FPGA) and a complex programmable logic device (CPLD) of a digital optical unit to add separate optical waves or to transmit complex data without specific changes in design of the optical frame.

• Proceedings of the Korean Society of Potoscience Conference
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• spring
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• pp.20-20
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• 1998

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.568-573
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• 2003

This paper describes a study of terrestrial digital TV transmission systems using wideband opto-electronic techniques such as electro-absorption modulators, wavelength division multiplex to support cost effective, high speed, flexible and interactive digital TV networks including ultra-high speed subscriber networks. In particular, the national DTV networks to be installed is required huge amount of cost. Therefore, the network should be carefully designed for DTV, communication and multimedia services in the future. In this paper, wideband optoelectronic DTV systems are suggested.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.25-28
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• 2019

Along with the development of information and communication technology, maritime communication systems also have been actively studied for navigation and communication equipment aiming at safety, efficiency, accuracy and security. However, for fishing ship over 100km far from the coast, it is difficult to manage such as location and status of ship. Therefore, in this study, for the safety of the long distance ship through Digital-HF communication system, we use method to choose the optimum frequency and it enables to check the position of ship.

• Journal of Korea Society of Digital Industry and Information Management
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• v.18 no.2
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• pp.39-48
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• 2022

The application of digital technology to instrumentation and control systems in nuclear power plants has overcome many shortcomings of analog technology, but the threat of cybersecurity has increased. Along with other systems, the reactor protection system also uses digital-based equipment, so responding to cybersecurity threats is essential. We generally determine cybersecurity threats according to the role and function of the system. However, since the instrumentation and control system has various systems linked to each other, it is essential to analyze cybersecurity threats together between the connected systems. In this paper, we analyze the cybersecurity threat of the reactor protection system with the associated facilities. To this end, we quantitatively identified the risk of the reactor protection system by considering safety functions, a communication type, the use of analog or digital-based equipment of the associated systems, and the software vulnerability of the configuration module of the reactor protection system.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.97-101
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• 2013

There is a growing need for optical communication systems that convert large volumes of data to optical signals and that accommodate and transmit the signals across long distances. Digital optical communication consists of a master unit (MU) and a slave unit (SU). The MU transmits data to SU using digital optical signals. However, digital optical units that are commercially available or are under development transmit data using two's complement representation. At low input levels, a large number of SSOs (simultaneous switching outputs) are required because of the high rate of bit switching in two's complement, which thereby increases the power noise. This problem reduces the overall system capability because a DSP (digital signal processor) chip (FPGA, CPLD, etc.) cannot be used efficiently and power noise increases. This paper proposes a change from two's complement to a more efficient method that produces less SSO noise and can be applied to existing digital optical units.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.43-59
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• 2019

The Traffic controller currently used in Korea is a switch control system that directly transfers 220V of high voltage to traffic lights one to one. This method requires a lot of cables, and there are concerns about electric shock. Accordingly, Korea Road Traffic Authority added the digital communication signal controller standard using digital communication method to the standard specification of the communication signal controller of the National Police Agency. Based on these specifications, this paper intended to develop digital communication call controllers. In addition, it was verified that even if the digital communication signal controller and analogue communication call controller were mixed, they could operate in the signal control system currently in operation.