• Journal of Hydrogen and New Energy
• /
• v.34 no.5
• /
• pp.505-513
• /
• 2023

Hydrogen infrastructure is expanding. High-capacity hydrogen refueling stations offer advantages because they can refuel a variety of light and heavy-duty vehicles, and multi-port refueling technology is developing to reduce charging time for heavy-duty vehicles. In this study, we suggest directions to lower the risk by analyzing the risk factors for each process involved in the installation of a high-capacity multi-port hydrogen refueling station in Changwon city. We conducted both qualitative and quantitative risk assessments of the equipment to evaluate the station. A hazard and operability study was performed for qualitative risk assessment, and PHAST/SAFETI were used for quantitative risk assessment. Quantitative risk assessment was used to calculate the consequence analysis of the facility to ensure secure design prior to station development and to predict individual and societal risks in various scenarios. As a result, the station's risk level was determined to be as low as reasonably practicable.

• Journal of Navigation and Port Research
• /
• v.42 no.6
• /
• pp.507-517
• /
• 2018

The probability of T/S cargo volume to decrease is the most notable problem associated with inappropriate mix of terminal operators in Busan port. Other problems include, the deterioration of the national carriers' competitiveness from non-operation of own terminal, excessively high proportion of financial operators in the engagement of operation which may result in their passiveness in timely investment, additional cost burden to carriers' in the handling inter-terminal T/S cargo transportation and inefficiency in terminal operation by the multiplicity of operators proved to be same recognized as so through the analysis. Therefore, in order to provide solutions for the problems and to strengthen Busan port's competitiveness, this research suggests the restructuring of operators mix as follows. To achieve sustainable growth of T/S cargo, global carriers' participation in terminal operation should be of utmost priority. To enhance the operational efficiency, the operators should be integrated. Similarly, the integration of operators will play a key role in verifying that national carriers' own terminal operation is an important factor in raising its competence. Finally, BPA's active engagement in the entire operation of port is also critical in public-oriented operation of the port. Whereas in the interactive analysis by taking the merits of Busan port into consideraion, global carrier's participation in operation, integration of operators and BPA's engagement in operation proved to contribute to the increase of T/S cargo and strengthening of operational efficiencies of Busan port.

• Journal of Navigation and Port Research
• /
• v.45 no.6
• /
• pp.352-359
• /
• 2021

This paper presents the definition and importance of ship-centric direct communication concerning ship safety of maritime autonomous and unmanned ships. It also proposes the concept of MX-S2X communication based on high frequency for wide-bandwidth technology and describes the design and simulation result for the physical layer of MX-S2X. It considered high-speed communication as well as overcoming maritime multi-path fading required to be resolved in the marine environment. The physical layer of MX-S2X communication was designed to overcome the occurrence of error-floor caused by multi-path fading even with receiving sufficient signal strength. To this purpose, a performance analysis was conducted on the physical layer by applying the channel model of the actual maritime communication environment. As a result of the performance analysis of the MX-S2X physical layer, it was confirmed that the BER error-floor observed in the VDE physical layer test was overcome, and it operated within the SNR 2dB degradation range compared to the AWGN channel. It is expected that this will show enough performance suitable for short-distance ship-centered direct communication and can be used for direct communication of maritime autonomous ships, unmanned ships, and group navigation of themshortly.

• Journal of Navigation and Port Research
• /
• v.43 no.1
• /
• pp.23-32
• /
• 2019

In this paper, we proposed a multi-chain Time of Arrival (ToA) positioning method to estimate positions using all received Loran-C signals from multiple chains without constraining to a single chain. Conventionally, we have to choose only one chain among several available chains for position estimation using Loran-C. Therefore, the number of signals to be used for positioning is limited to three to five. In general, if more signals are used for positioning estimation, its performance tends to be improved in terms of accuracy and availability. To validate the proposed method for multi-chain Loran-C, we firstly carried out a static positioning test in land. By analyzing the test results, we confirmed that the proposed method works well under a multi-chain Loran-C scenario. Subsequently, another mobile positioning test was conducted on board a vessel under a practical application scenario. From this second test, we successfully demonstrated that the multi-chain ToA positioning method even in situations where the conventional single-chain Loran-C approach fails for positioning.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.6
• /
• pp.1330-1335
• /
• 2013

In recent years, the need to simultaneously transmit a variety of signals, such as DVI(Digital Visual Interface), audio, video, USB(Universal Serial Bus), LAN from the computer is required. So the cable complexity and scalability issues have been raised. In this paper, this signal can be distributed using a single USB cable, computer, video, audio, USB, LAN, one USB multi-signal transmission system was designed and implemented. USB multi-signal transmission was implemented in order to convert a single DVI, audio, and multiple USB, LAN, USB signal converter modules. This USB DVI port supports up to 1920 * 1080 resolution. USB multi-signal transmission system by sending multiple signals into a single cable installation costs of the various cable and using the replication feature of the screen, will provide schools and institutes, etc., providing the convenience of the river, and the scalability of computer peripheral ports.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.3B
• /
• pp.339-348
• /
• 2004

Packet classification is an important factor to support various services such as QoS guarantee and VPN for users in Internet. Packet classification is a searching process for best matching rule on rule tables by employing multi-field such as source address, protocol, and port number as well as destination address in If header. In this paper, we propose hardware based packet classification algorithm by employing tree bitmap of multi-bit trio. We divided prefixes of searching fields and rule into multi-bit stride, and perform a rule searching with multi-bit of fixed size. The proposed scheme can reduce the access times taking for rule search by employing indexing key in a fixed size of upper bits of rule prefixes. We also employ a marker prefixes in order to remove backtracking during searching a rule. In this paper, we generate two dimensional random rule set of source address and destination address using routing tables provided by IPMA Project, and compare its memory usages and performance.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.10
• /
• pp.1957-1963
• /
• 2017

This paper has proposed a new-type groundwater auto-monitoring system based on Multi-Sensor Device. The system adopted Multi-Sensor Device as host computer of data acquisition, used Windows Mobile which was prevalent operation system of Multi-Sensor Device. It adopted serial port CAN and RS485 as the communication interface between goundwater sensor Device and monitor host machine and utilized serial-linked multi-sensor design to measure effectively according to the depth of groundwater. We present a design for a groundwater monitoring system based on a network of wirelessly linked sensors. The proposed solution will enable groundwater researchers and decision makers to have quick access to the groundwater data with less effort and cost. Though our design is initially meant for groundwater monitoring, it can be easily adapted to other fields of environmental monitoring.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.4
• /
• pp.1942-1950
• /
• 2013

This paper suggests a new method of detecting attacks of network traffic by visualizing original traffic data and applying multi-class SVM (support vector machine). The proposed method first generates 2D images from IP and ports of transmitters and receivers, and extracts linear patterns and high intensity values from the images, representing traffic attacks. It then obtains variance of ports of transmitters and receivers and extracts the number of clusters and entropy features using ISODATA algorithm. Finally, it determines through multi-class SVM if the traffic data contain DDoS, DoS, Internet worm, or port scans. Experimental results show that the suggested multi-class SVM-based algorithm can more effectively detect network traffic attacks.

• Journal of Navigation and Port Research
• /
• v.30 no.9
• /
• pp.767-772
• /
• 2006

Generally, a silicone rubber and a chlorinated polyethylene(CPE) have been used as a binder for the development of high-performance composite EM(Electro Magnetic) wave absorbers. In this paper, the EM wave absorption performance of natural lacquer, which is newly proposed as a binder was investigated. The prepared MnZn ferrite EM wave absorbers are mixed with natural lacquer showed excellent EM wave absorption characteristics compared with MnZn ferrite EM wave absorbers which are mixed with the conventional binders. MnZn ferrite EM wave absorbers mixed with natural lacquer were prepared and their absorption ability was also investigated The EM wave absorbers are fabricated in different proportions of MnZn, or NiZn ferrite and natural lacquer, and their reflection coefficients are measured. The permittivity and permeability are calculated by using the measured reflection coefficients. The EM wave absorption abilities are calculated according to different thicknesses of the EM wave absorbers.

• Journal of Navigation and Port Research
• /
• v.35 no.9
• /
• pp.755-763
• /
• 2011

Recently, extreme tsunami waves generated by submarine earthquake have caused tremendous damages to the coastal cities and ports. Strong seiche oscillations and runups are observed in specific sea areas around the world. Although no frequent impacts to the coast of Korean peninsula, there exist some important events in the east of Korea in the past. This study focuses on two historical events and recalculate with different fault and rupture mechanism for prediction considering the recent trend of submarine earthquake. The present study of the 1983 Akita tsunamis demonstrates the multi-scale resonance along continental coasts. Together with the Nankai tsunami for inland sea, we have confirmed the inland sea resonance surrounded by islands in defining the impact along the coast. Coherence and wavelet analyses for deducing a predominant period and time frequency are useful in reasoning the inundation. The resonance modes, which are largely independent of the tsunami source, allow identification of at-risk communities and infrastructure for mitigation of tsunami hazards. Furthermore, understanding of the resonance and the predicted runups for the site of power plant and industrial complex in the east coast of Korea would allow better preparation for the future disasters.