• Journal of the Society of Naval Architects of Korea
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• v.54 no.6
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• pp.501-514
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• 2017

In the previous research, a study was carried out to estimate the actual performance such as the propeller Revolution Per Minute (RPM) and engine power of a Liquefied Natural Gas Carrier (LNGC) using the full-scale measurement data. After the predicted RPM and engine power were verified by comparing those with the measured values, the suggested method was regarded to be acceptable. However, there was a limitation to apply the method on the prediction of the RPM and engine power of a ship. Since the information of route, speed, and environmental conditions required for estimating the RPM and engine power is generally regarded as the intellectual property of a shipping company, it is difficult to secure the information on a shipyard. In this paper, the RPM and engine power of the 151K LNGC was estimated using the combination of Automatic Identification System (AIS) and European Centre for Medium-Range Weather Forecasts (ECMWF) database in order to replace the full-scale measurement. The simulation approach, which was suggested in the previous research, was identically applied to the prediction of RPM and engine power. After the results based on the AIS and ECMWF database were compared with those obtained from the full-scale measurement data, the feasibility was briefly reviewed.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.4
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• pp.192-199
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• 2022

With the advent of autonomous ships, it is emerging as one of the very important issues not only to operate with a minimum crew or unmanned ships, but also to secure the safety of ships to prevent marine accidents. On-site inspection of the hull is mainly performed by the inspector's visual inspection, and video information is recorded using a small camera if necessary. However, due to the shortage of inspection personnel, time and space constraints, and the pandemic situation, the necessity of introducing an automated inspection system using artificial intelligence and remote inspection is becoming more important. Furthermore, research on hardware and software that enables the automated inspection system to operate normally even under the harsh environmental conditions of a ship is absolutely necessary. For automated inspection systems, it is important to review artificial intelligence technologies and equipment that can perform a variety of hull failure detection and classification. To address this, it is important to classify the hull failure. Based on various guidelines and expert opinions, we divided them into 6 types(Crack, Corrosion, Pitting, Deformation, Indent, Others). It was decided to apply object detection technology to cracks of hull failure. After that, YOLOv5 was decided as an artificial intelligence model suitable for survey and a common hull crack dataset was trained. Based on the performance results, it aims to present the possibility of applying artificial intelligence in the field by determining and testing the equipment required for survey.

• Korean Journal of Environment and Ecology
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• v.33 no.5
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• pp.596-604
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• 2019

This study conducted a sediment culture experiment to investigate the effects of sediment oxygen demand (SOD) and environmental factors on sediment and water quality. We installed a leaching tank in the laboratory, cultured it for 20 days, and analyzed the relationship between P and Fe in the sediment. As a result, the dissolved oxygen of the water layer decreased with time, while the oxidation-reduction potential of the sediment progressed in the negative direction to form an anaerobic reducing environment. The SOD was measured to be 0.05 mg/g at the initial stage of cultivation and increased to 0.09 mg/g on the 20th day, indicating the tendency of increasing consumption of oxygen by the sediment. The change is likely to have caused by oxygen consumption from biological-SOD, which is the decomposition of organic matter accumulated on the sediment surface due to the increase of chl-a, and chemical-SOD consumed when the metal-reducing product produced by the reduction reaction is reoxidized. The correlation between SOD and causality for sediment-extracted sediments was positive for Ex-P and Org-P and negative for Fe-P. The analysis of the microbial community in the sediment on the 20th day showed that anaerobic iron-reducing bacteria (FeRB) were the dominant species. Therefore, when the phosphate bonded to the iron oxide is separated by the reduction reaction, the phosphate is eluted into the water to increase the primary productivity. The reduced substance is reoxidized and contributes to the oxygen consumption of the sediment. The results of this study would be useful as the reference information to improve oxygen resin.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.3
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• pp.273-281
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• 2002

Determination of sediment type is generally based on ground truthing. This method, however, provides information only for the limited sites. Recent developments of remote classification of seafloor sediments made it possible to obtain continuous profiles of sediment types. QTC View system, which is an acoustic instrument providing digital real-time seabed classification, was used to classify seafloor sediment types in the Suyoung Bay, Pusan. QTC View was connected to 50 kHz echo sounder, All parameters of QTC View and echo sounder are uniformly kept during survey. By ground truthing, the sediments are classified into seven types, such as slightly gravelly sand, slightly gravelly sandy mud, gravelly muddy sand, clayey sand, sandy mud, slightly gravelly muddy sand, and rocky bottom. By the first remote classification using QTC View, four sediment types are clearly identified, such as slightly gravelly sand, gravelly mud, slightly gravelly muddy sand, and rocky bottom. These are similar to the result of the second survey. Also the result of remote classification matches well with that of ground truthing, but for sediment type determined by minor component. Therefore, QTC View can effectively be used for remote classification of seafloor sediments.

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

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.3
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• pp.81-90
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• 2013

The purpose of this paper is to do GIS-based suitable site selection using Scope for Growth index of Styela clava in Jindong Bay. The aquaculture of Styela calva is only conducted in Korea, especially Jindong Bay. Suspended culture of Styela clava was initiated in 2001 and the annual production reached 15,084M/T, but declined to 1,412M/T in 2005. The annual production was increased slightly to 2,484M/T in 2012 but the production is lower than the beginning yield. Scope for Growth(SFG) can indicate interrelationships between environment and organism growth index in aquaculture. GIS-based suitable site selection can be available by the concept of SFG, and fishery management system can be constructed for the sustainable production. As a result of the assessment of habitat suitability, Jindong Bay's SFG value ranges 0.054~0.57J/day and Styela clava farm's SFG values range 0.054~0.57J/day, either. The correlation between Styela clava farm's SFG and the actual production has a good result, as r=0.786, p<0.05. The construction of fishery management system using habitat suitability index ensures the reasonable site selection and the sustainable production in aquaculture farm. It introduces an objective method for the interrelationships between the environmental variation and the organism growth. Consequently, it can promote the decision making practices for the sustainable fishery management.

• Economic and Environmental Geology
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• v.40 no.4
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• pp.473-490
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• 2007

Strata of the Kachi-1 well, Kunsan Basin, offshore western Korea, were analyzed by using integrated stratigraphy approach. As a result, five distinct unconformity-bounded units are recognized in the well: Triassic, Late Jurassic-Early Cretaceous, Early Cretaceous, Late Cretaceous, and Middle Miocene units. Each unit represents a tectono-stratigraphic unit that provides time-sliced information on basin-forming tectonics, sedimentation, and basin-modifying tectonics of the Kunsan Basin. In the late Late Jurassic, development of second- or third-order wrench faults along the Tan-Lu fault system probably initiated a series of small-scale strike-slip extensional basins. Continued sinistral movement of these wrench faults until the Late Cretaceous caused a mega-shear in the basin, forming a large-scale pull-apart basin. However, in the Early Tertiary, the Indian Plate began to collide with the Eurasian Plate, forming a mega-suture zone. This orogenic event, namely the Himalayan Orogeny, continued by late Eocene and was probably responsible for initiation of right-lateral motion of the Tan-Lu fault system. The right-lateral strike-slip movement of the Tan-Lu fault caused the tectonic inversion of the Kunsan Basin. Thus, the late Eocene to Oligocene was the main period of severe tectonic modification of the basin. After the Oligocene, the Kunsan Basin has maintained thermal subsidence up to the present with short periods of marine transgressions extending into the land part of the present basin.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.549-556
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• 2017

Rivers continuously transport terrestrial organic carbon matter to the estuary and the ocean, and they play a critical role in productivity and biodiversity in the marine ecosystem as well as the global carbon cycle. The amount of terrestrial organic carbon transporting from the rivers to ocean is an essential piece of information, not only for the marine ecosystem management but also the carbon budget within catchment. However, this phenomenon is still not well understood. Most large rivers in Korea have a well-established national monitoring system of the river flow and the TOC (Total Organic Carbon) concentration from the mountain to the river mouth, which are fundamental for estimating the amount of the TOC flux. We estimated the flux of the total terrestrial organic carbon of five large rivers which flow out to the Yellow Sea, using the data of the national monitoring system (the monthly mean TOC concentration and the monthly runoff of river flow). We quantified the annual TOC flux of the five rivers, showing their results in the following order: the Han River ($18.0{\times}10^9gC\;yr^{-1}$)>>Geum River ($5.9{\times}10^9gC\;yr^{-1}$)>Yeongsan River ($2.6{\times}10^9gC\;yr^{-1}$)>Sumjin River ($2.0{\times}10^9gC\;yr^{-1}$)>>Tamjin River ($0.2{\times}10^9gC\;yr^{-1}$). The amount of the Han River, which is the highest in the Korean rivers, corresponds to be 4% of the annual total TOC flux of in the Yellow River, and moreover, to be 0.6% of Yangtze River.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.6
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• pp.1161-1170
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• 2019

In this study, we propose a model for predicting Cochlodinium polykrikoides red tide occurrence using deep neural networks. A deep neural network with eight hidden layers was constructed to predict red tide occurrence. The 59 marine and meteorological factors were extracted and used for neural network model training using satellite reanalysis data and meteorological model data. The red tide occurred in the entire dataset is very small compared to the case of no red tide, resulting in an unbalanced data problem. In this study, we applied over sampling with adding noise based data augmentation to solve this problem. As a result of evaluating the accuracy of the model using test data, the accuracy was about 97%.

• ALGAE
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• v.30 no.3
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• pp.217-222
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• 2015

Pythium species (Pythiales, Oomycetes) are well known as the algal pathogen that causes red rot disease in Pyropia / Porphyra species (Bangiales, Rhodophyta). Accurate species identification of the pathogen is important to finding a scientific solution for the disease and to clarify the host-parasite relationship. In Korea, only Pythium porphyrae has been reported from Pyropia species, with identifications based on culture and genetic analysis of the nuclear internal transcribed spacer (ITS) region. Recent fungal DNA barcoding studies have shown the low taxonomic resolution of the ITS region and suggested the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene as an alternative molecular marker to identify Pythium species. In this study, we applied an analysis of both the ITS and cox1 regions to clarify the taxonomic relationships of Korean Pythium species. From the results, the two closely related Pythium species (P. chondricola and P. porphyrae) showed the same ITS sequence, while the cox1 marker successfully discriminated P. chondricola from P. porphyrae. This is the first report of the presence of P. chondricola from the infected blade of Pyropia yezoensis in Asia. This finding of the algal pathogen provides important information for identifying and determining the distribution of Pythium species. Further studies are also needed to confirm whether P. chondricola and P. porphyrae are coexisting as algal pathogens of Pyropia species in Korea.