• Journal of Ocean Engineering and Technology
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• v.22 no.2
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• pp.65-71
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• 2008

Recently, many researches in relation to data transmission with faster speed and greater volume, many researches have been carried out on sonar systems for underwater communication. According to these researches, an acoustic transducer for underwater communication requires wide bandwidth properties. In domestic researches for underwater communication sonar, an operating frequency in the range of $20{\sim}40\;kHz$ is used. In this paper, we propose anon-resonance type acoustic transducer for underwater communication. The TVR (transmitting voltage response) characteristics increased linearly as the frequency increased, and the RVS (receiving voltage sensitivity) characteristics were constant as the frequency increased. Traditional techniques for wide bandwidth transducershave a limit and a transmission loss difference at lower and higher frequency operating ranges. In this paper, the new transducer proposed decreased the transmission loss under some conditions. It was optimized with the FE analysis tool (ATILA) and evaluated using the TVR and the RVS characteristics in the range of $10{\sim}90\;kHz$. The value of TVR was 138 dB at 20 kHz and 148 dB at 40 kHz, and the differences was 12 dB. The value of RVS was $195{\pm}2\;dB$ and nearly constant. From theseresults, it is certain that the developed transducers can be used for an underwater communication network in the 1.3 km range with both a 20 kHz bandwidth and 30 kHz center frequency.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.677-682
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• 2023

A large number of motors and sensors are used to drive a humanoid robot. In order to solve the wiring problem that occurs when connecting multiple actuators, a controller based on a communication network has been used, and CAN, which is advantageous in terms of cost and a highly reliable communication protocol, was mainly used. In terms of the structure of the controller, a torque control type structure that is easy to implement an advanced algorithm into the upper controller is preferred. In this case, the low communication bandwidth of CAN becomes a problem, and in order to obtain sufficient communication bandwidth, a communication network is configured by separating into a plurality of CAN networks. In this study, a stability analysis on transmission time delay is performed for a multi-motor control system in which high-speed FlexRay and low-speed CAN communication networks are hierarchically connected in order to obtain a high communication bandwidth, and sensor information and driving signals are delivered within the allowed transmission time. The proposed hierarchical network-based control system is expected to improve control performance because it can implement multiple motor control systems with a single network.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.401-406
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• 2005

The GFSK Transceiver of 400MHz ISM band for data communication is designed and fabricated. To reduce the occupied bandwidth of transmitted signal, the GFSK modulation is selected. The measured results of fabricated transceiver show the data rate of 2400bps at 8.5kHz bandwidth, frequency deviation of less than $\pm$3kHz, sensitivity of -111dBm, SNR of 21.58dB. The fabricated transceiver is satisfied with the regulation of radio wave and has the good performance. This transceiver is well suited for data communication of 400MHz ISM band.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1237-1240
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• 2009

인터넷의 발달로 금융기관의 일반업무도 인터넷을 사용하여 수행되는 비중이 커짐에 따라 이를 수용하기 위한 대역폭이 확보되어야 한다. 그러나 늘어나는 트래픽을 수용하기 위한 금융권 본-지점의 통신을 위한 전용회선 등은 상대적으로 비용이 많이 들기 때문에 금융기관 본-지점간의 네트워크 구성을 위하여 물리적인 회선의 증설 대신 현재 사용중인 회선의 트래픽을 효율적으로 운영하는 등의 새로운 기법이 필요하기에 이르렀다. 이에 본 연구에서는 계속적으로 증가되고 있는 금융기관의 웹 기반의 각종 트랜잭션 트래픽을 원활하게 수용하기 위한 방안으로써 비대칭 라우팅의 개선을 통하여 영업점 네트워크 OSPF 라우팅에 대한 변형 수용으로 대역폭 Load Sharing 개선에 관한 방안을 제안하였다. 새로운 라우팅 기법을 실제환경에 적용하여 회선의 사용률이 적절하게 분산되어 사용되고 Load Sharing 성능이 향상됨을 증명하였다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.286-286
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• 2006

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.5
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• pp.15-21
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• 2009

An Ethernet passive optical network (EPON) is an economical and efficient access network that received significant research attention in recent year. A MAC protocol of the PON, the next generation access network, is based primarily on TDMA (Time Division Multiple Access). In this paper, we addressed the problems of a dynamic bandwidth allocation (DBA) in Fairness and QoS Performance. We augmented the advanced bandwidth allocation algorithms to support efficient resource utilization by reducing the unused remaining bandwidth made by idle state ONUs. Our new proposed advanced bandwidth allocation algorithm can allocate effectively and fairly the bandwidths between end-users.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.167-172
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• 2012

This paper aims on comparative analysis of measuring efficiency of occupied bandwidth between MRTG average traffic and internet real-time traffic by measuring the type of internet application service. Through this analysis, the user can measure their internet line and occupy a certain amount of bandwidth and will have to invest on how much is compared to MRTG maximum traffic graph. The result of measurement proved 1.4 times to 20 times occupied bandwidth error rate between real-time and average traffic by the type of internet services.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.838-844
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• 2012

This paper proposes the effective monitoring method for marine engine system, which is implemented based upon Controller Area Network (CAN). As the marine engine monitoring system requires various kind of information, a lot of sensor nodes are distributed to several places. The CAN supports huge numbers of message IDs for the sensor nodes and provides a stable communication channel in a wide area such as a 12,000 TEU container ship. Since the CAN is priority-based communication system, some of hard real-time messages like alarm messages which are time-critical to the operation of the vessel cannot be communicated within the dead-time. Therefore it is desirable to distinguish the bandwidth of the CAN for static state messages and transition-state messages not to be harmful to the engine operations. Using the features of message arbitration ability of the CAN, it is proposed in this paper that the bandwidth allocation is dynamically adjusted to cope with the increment of input signal to improve the performance of monitoring system. Effectiveness and validity of the proposed scheme have been demonstrated through real experiments.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1287-1292
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• 2012

In this paper, a dual polarization patch antenna operates at the wide bandwidth of 1.525GHz~1.665GHz was designed and fabricated. To obtain the wide bandwidth and high gain, increased height of air floor from GND was applied, and to get wide band axial ratio and high gain, parasitic patch was applied. The simulation and measurement showed good agreements, the VSWR was less than 1.9 at the frequency bandwidth, the return loss was less than -10dB, and the LHCP(Left Hand Circular Polarization) and RHCP(Right Hand Circular Polarization) isolation was less than -13dB at the frequency bandwidth.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.1
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• pp.26-32
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• 2012

In this study, we proposed an intelligent algorithm for the performance improvement of ASK system for giga-bit modem in millimeter band. The proposed intelligent algorithm is a fuzzy logic system. The inputs to the fuzzy logic system are the remainder and integral of remainder that occurred counter of receiver, and the output is bandwidth of LPF. In order to verify the effectiveness of the proposed method, simulation is performed to the proposed system and the fixed bandwidth system, and is confirmed to the BER performance.