• Journal of Navigation and Port Research
• /
• v.47 no.6
• /
• pp.419-429
• /
• 2023

The pinnacle of rapidly changing and advancing maritime transportation technology is expected to be the Maritime Autonomous Surface Ship (MASS). The implementation of various services within the MASS is likely to be feasible through the ship-centric network known as the S2X communication system. However, existing communication systems face issues such as service traffic saturation and failure to meet demanded functionalities, necessitating the proactive introduction of additional communication technologies. In this study, the concept of S2X communication for the MASS was redefined, deriving required functionalities and ultimately selecting frequencies suitable for utilization. Candidate frequency groups suitable for the derived communication requirements were identified, and communication frequencies prioritized for the initial application were chosen through expert consensus. It is anticipated that through further research, including experimentation to validate these frequencies, they could be utilized in implementing services for autonomous ship navigation in the future.

• Journal of the Korea Society of Computer and Information
• /
• v.29 no.1
• /
• pp.111-119
• /
• 2024

In this paper, we propose a big data platform that can collect information from various sources collected at ocean. Currently operating ocean-related big data platforms are focused on storing and sharing created data, and each data provider is responsible for data collection and preprocessing. There are high costs and inefficiencies in collecting and integrating data in a marine environment using communication networks that are poor compared to those on land, making it difficult to implement related infrastructure. In particular, in fields that require real-time data collection and analysis, such as weather information, radar and sensor data, a number of issues must be considered compared to land-based systems, such as data security, characteristics of organizations and ships, and data collection costs, in addition to communication network issues. First, this paper defines these problems and presents solutions. In order to design a big data platform that reflects this, we first propose a data source, hierarchical MEC, and data flow structure, and then present an overall platform structure that integrates them all.

• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.2
• /
• pp.220-226
• /
• 2013

Recently, with the rapid development of factory automation and logistics system, a few workers were able to manage the broad workplace such as large vessels and warehouse. To estimate the exact location of these workers in the conventional wireless indoor localization systems, three or more fixed nodes are generally used to recognize the location of a mobile node consisting of a single node. However, these methods are inefficient in terms of node deployment because the broad workplace requires a lot of fixed nodes compared to workers(mobile nodes). Therefore, to efficiently deploy fixed nodes in these environments that need a few workers, this paper presents a novel estimation algorithm which can reduce the number of fixed nodes by efficiently recognizing the relative coordinates of two fixed nodes through a mobile node composed of three nodes. Also, to minimize the distance errors between mobile node and fixed node, rounding estimation(RE) technique is proposed. Experimental results show that the error rate of localization is improved, by using proposed RE technique, 90.9% compared to conventional trilateration in the free space. In addition, despite the number of fixed nodes can be reduced by up to 50% in the indoor free space, the proposed estimation algorithm recognizes precise location which has average error of 0.15m.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.9
• /
• pp.799-804
• /
• 2016

Broadband powerline communication (BPLC) uses distribution lines as a medium for achieving effective bidirectional data communication along with electric current flow. As the material characteristics of power lines are not good at the communication channel, the development of power line communication (PLC) systems for internet, voice, and data services requires measurement-based models of the transfer characteristics of the network suitable for performance analysis by simulation. In this paper, an analytic model describing a complex transfer function is presented to obtain the attenuation and path parameters for a multipath power line model. The calculated results demonstrated frequency-selective fading in multipath channels and signal attenuation with frequency, and were in good agreement with the experimental results. Inductive coupling units are used as couplers for coupling the signal to the power line to avoid physical connections to the distribution line. The inductance of the ferrite core, which depends on the frequency, determines the cut-off frequency of the inductive coupler. Coupling loss can be minimized by increasing the number of windings around the coupler. Coupling efficiency was improved by more than 6 dB with three windings compared to the results obtained with one winding.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.11 no.6
• /
• pp.123-132
• /
• 2012

Gas sensors has been used very differently that depending on following purposes; Automotive (exhaust gas, fuel mixture gas, oxygen, particulates), agriculture / food industry (fresh, stored, CO2, humidity, NH3, nitrogen oxide gas, organic gas, toxic gas emitted from pesticides and insecticides), industrial / medical (chemical gas, hydrogen, oxygen and toxic gases), military (chemical weapon), environmental measurements (CO and other air pollution consisting of sulfur and nitrogen gas), residential (LNG, LPG, butane, indoor air, humidity). The types of industrial toxic substances are known about 700 species and many of these exist in gaseous form under normal conditions. he multi-gas detection sensors will be developed for casualties that detect the most important and find easy three kinds of gases in marine plant; carbon dioxide(CO2), carbon(CO), ammonia(NH3). Package block consists of gas sensing device minor ingredient, rf front end, zigbee chip. Develope interworking technology between the sensor and zigbee chip inside a package. Conduct a performance test through test jig about prototype zigbee sensor module with rf output power and unwanted emission test. This research task available early address when poisonous gas leaked from large industrial site and contribution for workers' safety at the enclosed space.

• The Journal of the Acoustical Society of Korea
• /
• v.43 no.1
• /
• pp.9-18
• /
• 2024

The importance of active sonar systems is emerging due to the quietness of underwater targets and the increase in ambient noise due to the increase in maritime traffic. However, the low signal-to-noise ratio of the echo signal due to multipath propagation of the signal, various clutter, ambient noise and reverberation makes it difficult to identify underwater targets using active sonar. Attempts have been made to apply data-based methods such as machine learning or deep learning to improve the performance of underwater target recognition systems, but it is difficult to collect enough data for training due to the nature of sonar datasets. Methods based on mathematical modeling have been mainly used to compensate for insufficient active sonar data. However, methodologies based on mathematical modeling have limitations in accurately simulating complex underwater phenomena. Therefore, in this paper, we propose a sonar signal synthesis method based on a deep neural network. In order to apply the neural network model to the field of sonar signal synthesis, the proposed method appropriately corrects the attention-based encoder and decoder to the sonar signal, which is the main module of the Tacotron model mainly used in the field of speech synthesis. It is possible to synthesize a signal more similar to the actual signal by training the proposed model using the dataset collected by arranging a simulated target in an actual marine environment. In order to verify the performance of the proposed method, Perceptual evaluation of audio quality test was conducted and within score difference -2.3 was shown compared to actual signal in a total of four different environments. These results prove that the active sonar signal generated by the proposed method approximates the actual signal.

• Journal of the Korea Concrete Institute
• /
• v.20 no.1
• /
• pp.13-22
• /
• 2008

The initiation and growth processes of cyclic ice body in porous systems are affected by the thermo-physical and mass transport properties, as well as gradients of temperature and chemical potentials. Furthermore, the diffusivity of deicing chemicals shows significantly higher value under cyclic freeze-thaw conditions. Consequently, the disintegration of concrete structures is aggravated at marine environments, higher altitudes, and northern areas. However, the properties of cyclic freeze-thaw with crack growth and the deterioration by the accumulated damages are hard to identify in tests. In order to predict the accumulated damages by cyclic freeze-thaw, a regression analysis by the response surface method (RSM) is used. The important parameters for cyclic freeze-thawdeterioration of concrete structures, such as water to cement ratio, entrained air pores, and the number of cycles of freezing and thawing, are used to compose the limit state function. The regression equation fitted to the important deterioration criteria, such as accumulated plastic deformation, relative dynamic modulus, or equivalent plastic deformations, were used as the probabilistic evaluations of performance for the degraded structural resistance. The predicted results of relative dynamic modulus and residual strains after 300 cycles of freeze-thaw show very good agreements with the experimental results. The RSM result can be used to predict the probability of occurrence for designer specified critical values. Therefore, it is possible to evaluate the life cycle management of concrete structures considering the accumulated damages due to the cyclic freeze-thaw using the proposed prediction method.

• Journal of the Korea Society of Computer and Information
• /
• v.3 no.3
• /
• pp.139-150
• /
• 1998

Due to development of science and telecommunication with wide-spread computer supply, it could be done through computer automatically instead of manpower-work for paper transportation & paper approval. It is developed to so-called Factory Automation. Further, it is developed to Office Automation. Trading companies & concerned trade authorities are interested in Trade Automation that such technique is applied to trade work. Generally, Trade Automation means to realize paperless trade by exchanging electronic papers through inter-computers after concerned trade operators transformed various papers to electronic papers that computer could read. In case Trade Automation fix in the trade business, it is expected one of innovations among traditional paper work of trade business, namely without going import-export authorities, Customs office, Banks. Shipping companies, Marine insurance companies on hand-carrying papers, it could be fast, simple, correct to finish every trade procedures such as commercial business, foreign currency, customs clearance, transportations, insurance. terms of payment, etc., with Electronic Data Interchange through computer facilities. Especially, telecommunication for trade form could be helpful to proceed trade paper with one-run-method Further we can anticipate 6 effects for Trade Automation as belows : First, as explained just above articles, with completion for Trade Automation, every trade procedures can be done by computer. so, time to work can be diminished. namely. logistics cost including accessory costs for trade procedures can be saved much. Second, viewing to private enterprise, effect of Office Automation can be maximized and rapid, correct exchange for various trade informations could raise efficiency of enterprise management establishing rational production, storage, transportation and could raise competition improving standard for consumers's service. Third, establishing Trade Automation systems makes it easier piling-up of harbor cargo by pre-transmission of electronic paper & trade informations make it possible to finish customs clearance in advance and can be dispatched upon cargo arrival. Fourth, most of concerned trade authorities such as import-export approval office. financial authorities, transport & insurance companies concentrated in Metropolitan area(Seoul, In -Cheon, Kyung-Ki). Therefore, in case Trade Automation could be realized. it is possible to proceed trade business instantly in every country area by computer facilities. Also. it contribute well-balanced development for suburb. region area by suburb dispersion of trading companies. Fifth, on the way to Trade Automation establishment & its enlargement process. producing enormous demand for over-all telecommunication such as hardware. software. network makes opportunity to progress telecommunication industry & concerned industries. Finally. Trade Automation accelerate change of employment structure leading unnecessary labors on the industries of office & logistics to manufacturing area.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.5
• /
• pp.453-460
• /
• 2005

Since late 1970s, water quality monitoring had been performed in Korea by various agencies according to their own needs and objectives. Lacking of consistency in principles, such diverse operation has been producing difficulties in management of information on water quality parameters. These difficulties resulted from the fact that the expansion of monitoring networks had been based not on systematic methodology with considerations on scientifically established planning objectives but on personal experiences and subjective judgments in locating monitoring stations. This study aimed, therefore, to develop a selection methodology for locating monitoring stations to provide various informations on water quality to satisfy various monitoring objectives such as understanding short and long term trends of water quality, monitoring violations to water quality standards, identifying external causes and sources affecting water quality changes, supporting utilization of water resources, examining short-term variations in water quality through a concentrated investigation, estimating pollution loads from each unit watershed, supporting water quality modeling, and establishing informative systems for water resources management. Also, we applied the proposed methodology and presented an improved expansion plan for water quality monitoring networks in the Han River.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2006.06b
• /
• pp.265-271
• /
• 2006

According to globalization of world economy by extension of production, sales and distribution all around the world and international transportation system changed into a transport system that puts great importance on speediness and value-added services, international transport system is changing into a Multimodal Transport Routing centered system that systematically connects marine, air and rail transports. Due to such changes production, sales and distribution must be provided in time and Multimodal Transport Routing, which can provide multi-dimensional logistics services to customers of global network, is needed but information connection for international transport and connection system between transport modes are insufficient and can not be activated. Especially in Korea, selection standard of 3rd party logistics companies and transport companies is presented, but logistics exclusive companies, which plan and execute the transportation, can't present a systematic evaluation standard for international Multimodal Transport Routing, selection. Thus, this research surveys important previous studies about Multimodal Transport Routing, selection, derives an evaluation standard for Multimodal Transport Routing, selection through interview with company officials, and presents a theoretical basis for Multimodal Transport Routing, selection through systematic analysis of Multimodal Transport Routing, selection using Analytical Hierarchy Process (AHP).