• The Journal of the Acoustical Society of Korea
• /
• v.39 no.2
• /
• pp.69-76
• /
• 2020

This paper deals with a method of transmitting depth information of a high-speed underwater vehicle. The depth information signal transmitted from the high-speed mobile object is received with high frequency variability. In the proposed method, we apply not only frequency synchronization but also additional synchronization on the time axis like the existing method. In the case of a Doppler frequency bank with less resolution than the conventional method through simulations performed in the environment moving up to 50 kn, and the depth information is recovered using the proposed method, the error rate of 6 % ~ 9 % is reduced to 0.2 % ~ 1 %.

• Proceedings of the KIEE Conference
• /
• 2005.10b
• /
• pp.478-480
• /
• 2005

The AIS(Automatic Identification System) transmits the position of ships and other information to prevent accidents which could occur in the sea. It has to be developed SOTDMA(Self-Organized Time Division Multiple Access) Algorithm which is important on wireless communication method for the AIS because It is based on ITU(International Telecommunication Union) M.1371-1 of the international standard therefore, we need to develop a performance evaluation simulator efficiently to develop and analyze SOTDMA Algorithm. This paper shows the method of designing it. Real ships access The VHF maritime mobile band but in this performance evaluation simulator several ship objects access the shared memory. Real ships are designed as the object and the wireless communication channel is designed as the shared memory. The ships apply for real virtual data which got from assistance hardware and The SOTDMA Algorithm driving state verifies the performance evaluation simulator by IEC(International Electrotechnical commission) 61993-2. After verifying results the performance evaluation simulator is correctly satisfied with IEC 61993-2. So we expect that it helps not only the AIS technology developed but also verify new SOTDMA Algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.3
• /
• pp.547-553
• /
• 2004

Linux is the one of various RTOS, also embedded linux has being studied with focus on technical stability and commercial utilities. In this paper, the technical trial was discussed on the development of real-time operating system that provides real time capability and extends the network communications ability and would be applied to the maritime mobile communication system through analysis the embedded linux kernel. Some techniques for Analyzing the embedded linux kernel and designing the target board, making the kernel image and porting the kernel are summarized in this paper.

• Journal of Advanced Navigation Technology
• /
• v.13 no.2
• /
• pp.214-223
• /
• 2009

In this paper, we analysed and simulated the high speed mobile wireless channel for IEEE802.11p WAVE/DSRC standard draft. IEEE802.11p working group measured and suggested 6 channel model for WAVE/DSRC systems which is used for vehicle to vehicle or vehicle to infra communication. However, the models only provides numerical model, it did not provide Computer based software simulation model. So it can not be used directly for performance estimation of WAVE system. In this paper we suggested simulation technique of WAVE channel simulation which is developed S/W based WAVE channnel simulator. The simulation results for PSD, LCR, and AFD are also obtained, which can be used for performance estimation of IEEE802.11p based vehicular communication system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.2
• /
• pp.250-256
• /
• 2006

The revision of radio waves act, which took effect on July 1,2005, widened the bandwidth of PLC from $9kHz{\sim}450kHz$ to $9kHz{\sim}30MHz$. This high upper limit of frequency may cause the interference in HF wireless communications. From this point of view, the goal of this research is to suggest the estimation method of whether-or-not the interference occurs and furthermore offer countermeasures to avoid it hereafter. Ministry of Information and Communication Radio Research Laboratory(MIC-RRL)has been researching for the interference and devoting themselves to turn out how much it affects to HF wireless communications since the revision took effect. This research suggests some estimation methods with receivers, signal generators, or SINAD(Signal to Noise and Distortion) Meter which is so suitable for the RF environment that we can overcome the existing limit to the EMC environment. In addition, this research is focused on securing the environment for wireless communications by establishing the safety zone or suggesting the ways to prohibit the use of the bandwidth, which may cause serious interference, in order to minimize the effect of PLC on HF maritime mobile telecommunications.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.8
• /
• pp.1098-1104
• /
• 2011

Data communications networks at sea can be modelled by multi-layered networks with traditional carriers (RF, satellites), and BWA (wireless LAN, WiBro, LTE), which partially makes it possible the high speed communication services (WWW, VoIP) at sea. In this paper, a novel routing scheme (CPR) is proposed which selects an optimal carrier for each hop in routes based on carrier preferences (CP). The carrier preferences are measured proactively depending on the feasibility of transmission characteristics (transmission rate, cost, and latency time) of the carriers for each application. Performance was compared with that of the OMH-MW (Optimal Medium per Hop based on Max-Win) routing scheme.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2007.10a
• /
• pp.223-228
• /
• 2007

In this paper, Wideband antenna using E-shaped stacked patches has been designed and fabricated for 4th generation mobile communication(IMT-Advanced) AccessPoint application. E-shaped patch was miniature and brodband by made the movement route of current long. And inductive of coaxial probe compensates capacitive by slot. Therefore we fabricated to improve the bandwidth of proposed antenna. The E-shaped single patch antenna has an impedance bandwidth of about 13%(510[MHz]), By adding a second patch at the top of the first patch a bandwidth of 56%(2060[MHz]). The final fabricated antenna could have a good return loss(Return loss ${\leq}-10dB$) and a high gain(over 9.6dBi) at the range of 3.23 ${\sim}$ 5.29 [GHz].

• Journal of Advanced Navigation Technology
• /
• v.24 no.6
• /
• pp.601-606
• /
• 2020

In this paper, we designed a microstrip patch antenna that can be applied to the Wimax/LTE 5G system among wireless media usable in coastal ships. The substrate of the proposed antenna is FR-4 (er=4.3), the size is 22 mm × 30 mm, and it can be used in the 3.5 GHz and 5.8 GHz bands of Wimax/LTE 5G by constructing a simple structure using a microstrip patch antenna. CST Microwave Studio 2014 was used for simulation, and the gain of the simulation result is 2.41dB at 2.4 GHz and 3.96 dB at 3.5 GHz. S-Parameter also showed a result of less than -10 dB (VSWR 2:1) in the desired frequency band, and designed a small variable and a miniaturized antenna so that the antenna can be used in mobile phones or electronic devices.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.11
• /
• pp.1446-1455
• /
• 2016

The recent increase of fresh farm products, hazardous cargos, and high-priced goods in marine transportation has caused an increased demand of cargo owners and shipping companies with regard to the monitoring of the location and state of cargo. To meet this increase, numerous technologies are being studied for the monitoring of the cargo state. Cargo containers on a ship are loaded on a ship's deck and in a ship's hold, which is located under the deck. However, Since the developed technologies mostly transfer the container status information that collected by mobile communication, it costs a lot to install communication infrastructure on ship. And the ship's hold is completely sealed with a cover, and communication with the reader positioned at the ship's bridge is difficult. Therefore, most existing studies on container monitoring on ships have focused on the monitoring of containers loaded on a ship's deck. Accordingly, this study suggested system configuration for the monitoring of containers in a ship's hold using IP-RFID technology. The suggested system configuration was tested on an actual ship under navigation, and the test results are given in this study. The test results verified that the monitoring of containers in a ship's hold using IP-RFID technology is effective.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.8
• /
• pp.1092-1097
• /
• 2011

Data communications at sea are done by the traditional radio and satellite carriers. Because of the restrictions on the data rate and cost of the carriers, a novel data communication system at sea is needed. Nowadays the efforts to make use of the broadband land carriers at sea have been pursued. This paper proposes a routing scheme (NTCR) using the various carriers on land for a MANET model at sea. The NTCR scheme optimizes the route using a chosen carrier by taking considerations of normalized transmission characteristics (NTC) of applications and carriers. The NTCR scheme is compared with the MWR (max-win based routing) scheme.