• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.50 no.1
• /
• pp.75-82
• /
• 2014

In vibration analysis of ships, the principle aim is to determine the natural frequencies and excitation frequencies, and use this information to avoid resonances and vibration damage. The simplest method is to prevent resonance conditions, which is effective as long as the natural frequencies and excitation frequencies can be regarded as independent from environmental conditions. For ships that use electric propulsion systems, the sources of vibration are reduced compared with those caused by a diesel engine or other combustion-based propulsion systems. However, the frequency spectrum of these vibrations may be different; therefore, to understand the characteristics of the electric propulsion, we also should investigate how the ship responds to these vibrations. We focused on a 1,000-ton deadweight (DWT) ocean-research vessel using an electric propulsion system and analyzed the response to vibration.

• Korean Journal of Environmental Biology
• /
• v.38 no.1
• /
• pp.179-188
• /
• 2020

The influx of marine exotic and alien species is disrupting marine ecosystems and aquaculture. Herdmania momus, reported as an invasive species, is distributed all along the coast of Jeju Island and has been confirmed to be distributed and spread to Busan. The potential habitats and distribution of H. momus were estimated using the maximum entropy (MaxEnt) model, quantum geographic information system (QGIS), and Bio-ocean rasters for analysis of climate and environment(Bio-ORACLE), which can predict the distribution and spread based only on species occurrence data using species distribution model (SDM). Temperature and salinity were selected as environmental variables based on previous literature. Additionally, two different representative concentration pathway (RCP) scenarios (RCP 4.5 and RCP 8.5) were set up to estimate future and potential habitats owing to climate change. The prediction of potential habitats and distribution for H. momus using MaxEnt confirmed maximum temperature as the highest contributor(77.1%), and mean salinity, the lowest (0%). And the potential habitats and distribution of H. momus were the highest on Jeju Island, and no potential habitat or distribution was seen in the Yellow Sea. Different RCP scenarios showed that at RCP 4.5, H. momus would be distributed along the coast of Jeju Island in the year 2050 and that the distribution would expand to parts of the Korea Strait by the year 2100. RCP 8.5, the distribution in 2050 is predicted to be similar to that at RCP 4.5; however, by 2100, the distribution is predicted to expand to parts of the Korea Strait and the East Sea. This study can be utilized as basic data to effectively control the ecological injuries by H. momus by predicting its spread and distribution both at present and in the future.

• Journal of Environmental Science International
• /
• v.22 no.4
• /
• pp.481-492
• /
• 2013

In this study, the use survey of domestic and international weather information on coastal regions and the demand survey (e.g. general and in-depth surveys) for customer needs with coastal industries were carried out to design customized coastal weather contents. The general demand survey showed that most of the customers working in the coastal industries were interested in a short-term forecast, such as a general weather outlook (approximately 29% of the total respondents) and typhoon information (19%), and they preferred to be given the forecast information from new media such as the internet web-pages (36%) and mobile utilities (23%) rather than old media such as TV (16%) and radio (11%). In addition, only 31% of the total respondents were found to be satisfied with the use of the current coastal weather service. This low percentage might mainly be a result of lack of information accuracy (about 64%) and diversity (28%). From in-depth survey with site visiting, the need of coastal weather contents, such as weather elements, data form, a tool of communication, and forecast interval, differed with the working stages in three coastal industries (e.g. shipbuilding, maritime trade, and passenger transport industries).

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2001.10a
• /
• pp.15-19
• /
• 2001

Electronic navigation system onboard have have been developed with recent technology based on new concept such as electronic chart date. The most valuable system of revolution in electronic navigation equipment is ECDIS, which have been developed in order to reduce work load of mariner and give an integrated information by simple means, especially to improve the safety of ship's navigation. In order to be sure the function of ECDIS is satisfied, The international standard have regulated the performance in the standard, so ECDIS should be type approved by the marine equipment authority of each government. There are three basic documents, IEC61174, IEC61162, IEC60945 issued by IMO(International Maritime Organization) which should be used for type approval system of each authority. IEC 61174 include the method of test and required results for operational and functional performance of test equipment. IEC61162 is for sensor interface and IEC60945 is related to the test of environmental condition for general marine radiocommunication equipment. In this paper, we investigate international standard in detail and current approval system of general marine equipment. After that, we present the possible structure of type approval of ECDIS and important considerations of approval system such that ECDIS should be tested as one system not be separated between S/W and H/W.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2007.12a
• /
• pp.87-100
• /
• 2007

Marine controlled source electromagnetics (CSEM) or sea bed logging (SBL) is an emerging technology which can provide quantitative information on hydrocarbon reservoir embedded in marine sediment. Electromagnetic responses to the resistive formation saturated with a certain amount of hydrocarbon can be characterized by less attenuated profile otherwise exponentially attenuated fields in conductive sea water or through sediments, and thus can be regarded as a direct indicator of hydrocarbon. In this paper, we introduce the technology of marine CSEM in terms of its physical characteristics and in comparison of typical three-dimensional (3-D) seismic method. History and evolution of commercial marine CSEM are also briefly summarized. We then introduce a representative case history showing how marine CSEM works in reality. Outlook of future applications and technical advances to be made are discussed. Finally, we demonstrate a test example of 2.5-D inversion of synthetic data as the groundwork of 3-D inversion of field data that is to be the ultimate goal of technical development.

• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.253-256
• /
• 2005

The use of satellite remote sensing in maritime safety and security can aid in the detection of illegal fishing activities and provide more efficient use of limited aircraft or patrol craft resources. In the area of vessel traffic monitoring for commercial vessels, Vessel Traffic Service (VTS) which use the ground-based radar system have some difficulties in detecting moving ships due to the limited detection range. A virtual vessel traffic control system is introduced to contribute to prevent a marine accident such as collision and stranding from happening. Existing VTS has its limit. The virtual vessel traffic control system consists of both data acquisition by satellite remote sensing and a simulation of traffic environment stress based on the satellite data, remotely sensed data. And it could be used to provide timely and detailed information about the marine safety, including the location, speed and direction of ships, and help us operate vessels safely and efficiently. If environmental stress values are simulated for the ship information derived from satellite data, proper actions can be taken to prevent accidents. Since optical sensor has a high spatial resolution, JERS satellite data are used to track ships and extract their information. We present an algorithm of automatic identification of ship size and velocity. This paper lastly introduce the field testing results of ship detection by RADARSAT SAR imagery, and propose a new approach for a Vessel Monitoring System(VMS), including VTS, and SAR combination service.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.9 no.3
• /
• pp.58-66
• /
• 2006

Environmental Sensitivity Index Map(ESI Map) is useful information for efficient and prompt contolling of oil spill accident. Environmental sensitivity information relating to oil spill is very various, so efficient access and utilization for environmental sensitivity information at control field is required. In order to improve the efficiency of controlling accident at the field, it is necessary to building digital ESI Map and GIS program. In this study, GIS database was built to utilize environmental sensitivity information at Yeosu and Gyunggi bay. And the ESI Map program which is focused on the control job was developed. IMO/IPIECA's guide to make the ESI Map and Korea Coast Guard's guide to collect information for the control information map were referenced to capture environmental sensitivity data and build GIS database. The symbology of environmental sensitivity layers was defined and functions for supporting control job were implemented in ESI Map program. For the future works, the program in this study could be applied to ESI Map program for the whole coastal area of Korea and it could be the essential element technology in marine pollution control supporting system.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.44 no.1
• /
• pp.37-45
• /
• 2008

Assessment and management of fisheries abundance in fresh water like a river or a lake is very important to maintain fisheries itself as well as tourist industry even if their scale is not much large. The species for catch in fresh water are mainly a mandarin fish, a carp, an eel, and others. Because oriental river prawn is a main prey of these species and the change in its abundance is directly related to their abundance change in fresh water, information on the abundance and distribution of the species are necessary. Hydroacoustic survey is known to one of the efficient method among several methodology. Information on acoustic target strength is key parameter to estimate abundance for acoustic survey. In this study, measurements on oriental river prawn, Macrobrachium koreana, were conducted for two high frequencies(200kHz and 420kHz) with tilt angle using automatic rotating system. The results of acoustic target strength obtained from the experiment were compared with those of acoustic scattering model, Distorted Wave Born Approximation(DWBA) model. For 200kHz, the result of acoustic target strength experiments was expressed in terms of the averaged target strength dependence on the body langth(BL, cm) as a following relationship; < $TS_{200kHz}$ > = 45.9log(BL) - 107.4. These results provide basic information for studying acoustic target strength and conducting acoustic survey of oriental river prawn.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.6
• /
• pp.542-547
• /
• 2016

In recent times, Internet of Things (IoT) has attracted wide attention, and there are increasing requests for IoT application services. Open-Source Hardware (OSH) utilizes a variety of components that are created through the sharing of hardware design so that others developers can also work on it. The concept of "open source" that attracted attention in the software industry has been applied to the hardware field by the emergence of IoT market. The emergence of OSH that has the advantage of low hardware cost and faster development encourages the idea of a diverse IoT application services. In this paper, we describe an IoT application service system that is developed using the OSH platform Arduino and Raspberry Pi to process collection, exchange, and computation of the environmental information. The overall system architecture and hardware and software components are presented.

• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.5
• /
• pp.705-712
• /
• 2009

The state changes of ocean covered over 70% of earth surface are one of the greatest factor of weather catastrophe. Recently weather extraordinary events are followed by steep increase of sea water temperature and scientists in various fields are studying and warning the weather changes. In this paper, floating buoy is developed to monitor ocean environments via Orbcomm satellite and a method is proposed to increase measurement accuracy of sea water temperature with common low price temperature sensor. Experimental results are presented to illustrate the usability and effectiveness of the developed system. A web-based real time monitoring system is built to monitor ocean environmental information such as sea and air temperature, salinity according to the position of buoy through the internet for user convenience.