• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.145-151
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• 2017

In this paper, we propose the design and implementation of the system that is predicting the failure of ballast water treatment system by analysing its sensor datum and is reserving the most effective service center for sellecting the repair location on the way to the destination port. These data are collected in real time during draining or filling up the sea water from/to the ship, and it is essential to preliminarily repair the equipment showing unstable characteristics by analyzing the normal and abnormal data characteristics. We proposed a software platform for predicting and repairing faults by selecting the most efficient repair center based on this e-Navigation while the vessel is navigating to the next destination port. This system, as announced by the IMO Convention for the Prevention of Marine Pollution in 2017, provides a stable economic impact from stable cargo operation and stable out/in from/to port and marine ecosystem.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.11
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• pp.1025-1033
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• 2011

In this paper, we introduce the contactless power transmission device for transmitting the power with the resonant characteristic of the cavity resonator. When transmitting the power, the contactless power transmission device begins to work in the condition where the transceiver adheres closely. The transceiver is electrically separated because there is no conductive terminal outside and the size of the receiver required for the electric power transmission can be minimized. The cavity resonator comprises slots for the input port and output port in the upper side conductor plate of the cavity and forms the input port and output port using the stripline structure at this upper part. The some of output port is separated from it and the electric power receiver is formed thus the union can be possible. The rest except electric power receiver become the electric power transmitter, which includes the input port of stripline-slot coupling, cavity, and the slot of the output port. If the transmitter and the receiver are combined, they become the form in which the electricity is transferred from the input port to the output port in a cavity resonator. The center frequency of the contactless power transmitter manufactured is 5.782 GHz. and $S_{21}$ is measured as -1.07 dB. It is confirmed that the high electric power transfer rate is approximately 78 %.

• Journal of Korea Port Economic Association
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• v.30 no.4
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• pp.199-217
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• 2014

There have been relatively lots of studies on the relationships beteen port and city. And, most of the recent studies on the subject shows that the relationship between the two parties is weakening. The contributions of a port to the city economy such as convenience of logistics service utilization, cost reduction, creation of job opportunities and value added production etc. are diminishing, whereas negative effects of port such as environmental effects, limitation of waterfront activities etc. have been increasing. On the other hand, port logistics service demand from city economy is decreasing. As for Busan city, the trend of major economic indicators and growth factor analysis results show that there is hardly any relationships between the development of transportation industry(including port logistics) and the regional economy. Especially, it is identified that most regional industry sectors excluding transportation industry failed to secure competitive advantage. Accordingly, it can be concluded that Busan city economy fails to take advantage of advanced transportation industry sector, which supports overall economic activities. On the other hand, it can be a problem for enhancement of port-city relationships that related and supporting industries of transportation industry such as information and communication industry, financial and insurance industry, and processing and assembling manufacture industry fail to secure competitive advantage in Busan city.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.11
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• pp.2267-2272
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• 2009

The six-port direct conversion receiver front-end that is comprised of a carrier recovery and a phase shifter, which gets the same structure with six-port phase correlator using the multi-layer coupled line, was designed and fabricated in this paper. The six-port element that is comprised of the power divider and the hybrid coupler is designed by multi-layer coupled line structure. The multi-coupled structure is utilized as the basic structure in receiver phase correlator, carrier recovery circuit and phase shifter. The receiver front-end with the same multi-layer coupled line structure for the receiver elements shows the simple structure and no difficulty in integration. The fabricated multi-layer coupled six-port receiver front-end re-generates the carrier signal with a constant phase and demodulates the PSK transmission signal.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.11
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• pp.1687-1695
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• 2021

In this paper, it is designed and analyzed the beamforming antenna using the butler matrix. The operating frequency of the proposed beamforing antenna is ISM band of 2.4 GHz band and the component of the beamforing antenna consisted of a 1×4 array antenna and a 4×4 butler matrix. Each output port of 4×4 butler matrix outputs the signal having a different phase, it is provided to each input port of 1×4 array antenna. The beamforming antenna with four output ports forms a total of four beams. In order to analyze the radiation pattern of the beamforming antenna, it was provided by switching the signal to the input port and proceeded the Individual analysis for the input port 1 to 4. The main beams of the proposed beamforming antenna were formed in the -12°, 40°, -40° and 12° directions according to each input port, respectively.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.2
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• pp.251-258
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• 2023

In this paper, we propose DLP(Dual Linear Polarization) stack antenna for private network. The proposed antenna has general stack structure and design airgap between two substrate to obtain the maximum gain. Also, to improve cross polarization isolation, two feeding port is designed to separate for each substrate. The size of each patch antenna is 17.80 mm(W1)×16.70 mm(L1) for lower patch and 18.56 mm(W2)×18.73 mm(L2) for upper patch, which is designed on the FR-4 substrate which thickness (h) is 1.6 mm, and the dielectric constant is 4.3, and which is 40.0 mm(W)×40.0 mm(L) for total size of substrate. From the fabrication and measurement results, bandwidths of 100 MHz (4.74 to 4.84 GHz) for feeding port 1, and 150 MHz (4.67 to 4.82 GHz) for feeding port 2 are obtained on the basis of -10 dB return loss and transmission coefficient S21 is got under the -20 dB. Also, cross polarization isolation between each feeding port obtained

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1015-1022
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• 2023

In this paper, we propose DLP(Dual Linear Polarization) antenna with aperture coupled feeding structure for private network. The proposed antenna has general aperture coupled structure and design two port between top and bottom layer to obtain the enhanced isolation. Also, The size of each substrate(top and bottom layer) is 34.0 mm(W)×34.0 mm(L), which is designed on the FR-4 substrate which thickness (h) is 1.0 mm, and the dielectric constant is 4.4. Also, the size of patch antenna is 12.70 mm(W2)×14.60 mm(L3), and it is located on the top layer. The size of feeding line is 24.0 mm(W2)×1.6 mm(L3), and is located at the bottom layer Also, rectangular slot is located on the ground plane between top layer and bottom layer. From the fabrication and measurement results, bandwidths of 300 MHz (4.52 to 4.82 GHz) for feeding port 1, and 170 MHz (4.65 to 4.82 GHz) for feeding port 2 are obtained on the basis of -10 dB return loss and transmission coefficient S21 is got under the -30 dB. Also, cross polarization isolation between each feeding port obtained

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.3
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• pp.256-265
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• 2017

In this paper, an ascheme is proposed for multiuser underwater acoustic communication by using the multi-chirp rate signals. It differs from the well known TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access) or CDMA (Code Division Multiple Access), by assigning each users with different chirp-rate carriers instead of the time, frequency or PN code. Multi-chirp rate signals can be separated from each other by FrFT (Fractional Fourier Transform), which can be regarded as the chirp-based decomposing, and superior to the match filter in the underwater acoustic channel. VTRM (Virtual Time Reverse Mirror) is applied into the system to alleviate the ISI caused by the multipatch and make the equalization more simple. Results of computer simulations and pool experiments prove that the proposed multiuser underwater acoustic communication based on the multi-chirp rate exhibit well performance. Outfield experments carrie out in Xiamen Port show that using about 10 kHz bandwidth, four users could communicate at the same time with 425 bps with low BER and can match the UAC application.

• Journal of the Korean Institute of Navigation
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• v.17 no.2
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• pp.75-106
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• 1993

GMDSS(Global Maritime Distress and Safety system) is a new communication system for the distress and safety at sea which is utilizing the recent advancements in satellite communication and positioning system, digital communication system, computer and microelectronic technology, etc., and will completely substitute the current communication system by 1999. Although the improvements of education for producing qualified Radio Operators as well as the establi-shments of policy for accepting the system are required, the educational institutions and relating administ-rations have not yet prepared the rational and concrete schemes on the educational methods and accepting procedures for the system. In this study, as the result of analyzing the GMDSS, courses of training and relating data, the authors suggested principles for improving the course and contents of education and rational schemes for balan-cing the demand and supply of Radio Operators. The authors expect not only the consequences of this study can be utilized as reference materials for the instruction to ratio communication in the organs of education but also that the following effects can be obtained by the study. 1. Security of distress and safety communication system at sea by the establishment of relating regula-tions. 2. Rationalization of the management of radio communication at sea and improvement of the communi-cation system on the vessel. 3. Upgrading the quality of Radio Operators and presenting schemes for current qualified persons. 4. Activation of industry producing radio instruments. 5. Balance of the demand and supply of Radio Operators and development of shipping industry.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.2
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• pp.287-312
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• 2011

Internet chat programs and instant messaging services are becoming increasingly popular among Internet users. One of the crucial issues with Internet chat is how to manage the corresponding pairs of questions and answers in a sequence of conversations. Although many novel methodologies have been introduced to cope with this problem, most are poor in managing interruptions, organizing turn-taking, and conveying comprehension. The Internet environment is recently evolving into a 3D environment, but the problems with managing chat dialogues with the standard 2D text-based chat have remained. Therefore, we propose a more realistic communication model for chat agents in 3D virtual space in this paper. First, we propose a new method to measure the capacity of communication between chat agents and a novel visualization method to depict the hierarchical structure of chat dialogues. In addition, we are concerned with communication networks for virtual people (avatars) living in virtual worlds. In this paper we consider a microscopic aspect of a social network in a relatively short period of time. Our experiments show that our model is highly effective in a virtual chat environment, and the communication network based on our model greatly facilitates investigation of a very large and complicated communication network.