• Journal of the Korean Society of Marine Environment & Safety
• /
• v.28 no.5
• /
• pp.780-790
• /
• 2022

Quantitative risk levels must be presented by analyzing the causes and consequences of accidents and predicting the occurrence patterns of the accidents. For the analysis of marine accidents related to vessel traffic, research on the traffic such as collision risk analysis and navigational path finding has been mainly conducted. The analysis of the occurrence pattern of marine accidents has been presented according to the traditional statistical analysis. This study intends to present a marine accident prediction model using the statistics on marine accidents related to vessel traffic. Statistical data from 1998 to 2021, which can be accumulated by month and hourly data among the Korean domestic marine accidents, were converted into structured time series data. The predictive model was built using a long short-term memory network, which is a representative artificial intelligence model. As a result of verifying the performance of the proposed model through the validation data, the RMSEs were noted to be 52.5471 and 126.5893 in the initial neural network model, and as a result of the updated model with observed datasets, the RMSEs were improved to 31.3680 and 36.3967, respectively. Based on the proposed model, the occurrence pattern of marine accidents could be predicted by learning the features of various marine accidents. In further research, a quantitative presentation of the risk of marine accidents and the development of region-based hazard maps are required.

• Journal of Marine Bioscience and Biotechnology
• /
• v.4 no.1
• /
• pp.11-14
• /
• 2010

The genus Porphyra, consisting of 133 species includes several economically valuable species (i.e. P. yezoensis, P. tenera, P. pseudolinearis etc.). They are predominantly consumed and cultivated in East Asian countries such as Japan, Korea and China, and they are regarded as a big commercial market today. In addition to the industrial importance, P. yezoensis is currently regarded as a feasible candidate for a model plant in marine biotechnology, therefore there are a wide range of studies being undertaken: strain-preservation, development of mutant strains and genetic analysis and exhaustive molecular analysis including EST and macro/micro array. Focusing on the activities of our research group, current situation and future perspectives in marine biotechnological studies using P. yezoensis will be discussed in this mini review.

• Journal of Ship and Ocean Technology
• /
• v.10 no.2
• /
• pp.11-23
• /
• 2006

The model exchange from CAD system to CAE system in valid and effective manner is the major issue of automatic analysis modelling of ship structure. However, model exchange approaches based on the neutral CAD file have resulted in invalid model exchange that could not properly reflect the characteristics of CAD model and CAE model of ship structure. This paper presents the new approach of n-to-n mapping to exchange ship structure model in heterogeneous CAD/CAE environments. In this study, the common model called 'unified ship model for analysis' to directly extract proper information from different CAD systems for ship structural analysis is proposed. Moreover, a command language based model interfacing technique to construct an idealized model for analysis job is also proposed. The proposed approach has been actually implemented in DSME CAD/CAE environment of ship structure such as TRIBON system, PATRAN system and FLUENT system. The applicability and effectiveness of the proposed approach was verified by applying it to the real analysis project for fore-body of ship and block lifting. This application results show that the proposed approach can be effectively used for heterogeneous CAD/CAE environment.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.54 no.2
• /
• pp.194-207
• /
• 2021

It is necessary to assess and manage the different elements of the marine ecosystem, such as climate change, habitat, primary and secondary production, energy flow, food web, potential yield, and fishing, to maintain the health of the ecosystem as well as support sustainable development of fishery. We set up an ecosystem model around the Korean peninsula to produce scientific predictions necessary for the assessment and management of marine ecosystems and presented the usability of the model with scenario experiments. We used the Atlantis ecosystem model based on the marine food web; Atlantis is a three-dimensional end-to-end model that includes the information and processes within an entire system, from an abiotic environment to human activity. We input the ecological and biological parameters, such as growth, mortality, spawning, recruitment, and migration, to the Atlantis model via functional groups using existing research and local measurements. During the simulation period (2018-2019), we confirmed that the model reproduced the observed data reasonably and reflected the actual ecosystem characteristics appropriately. We thus identified the usability of a marine ecosystem model with experiments on different environmental change scenarios.

• Journal of Navigation and Port Research
• /
• v.36 no.9
• /
• pp.741-751
• /
• 2012

This article analyzes the interdependency between nonrenewable marine sand resources and renewable fishery resources by the developed dynamic bioeconomic model. The developed bioeconomic model is applied to a case study of efficient sustainable management for marine sand mining, which adversely affects a valuable blue crab fishery and its habitat in Korea. The socially-efficient extraction plan for marine sand and the time-variant environmental external costs to society in terms of diminished harvest rate of blue crab are determined. To take into account long-term effects from destroyed fishery habitat, a Beverton-Holt age structure model is integrated into the bioeconomic model. The illustrative results reveal that the efficient sand extraction plan is dynamically constrained by the stock size of the blue crab fishery over time. Thus, the dynamic environmental external cost is more realistic resource policy option than the classical fixed external cost for determining socially optimal extraction plans. Additionally, the economic value of bottom habitat, which supports the on- and off-site commercial blue crab fishery is estimated. The empirical results are interpreted with emphasis on guidelines for management policy for marine sand mining.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2007.06a
• /
• pp.317-322
• /
• 2007

Seismic exploration is divided by reflection and refraction method greatly, and reflection method can analyze complicated underground structure in the basis high resolution image, and refraction method can grasp the velocity structure of underground accurately. This thesis confirmed application of mixed exploration techniques using advantages of reflection and refraction. Reflection data processing applied conventional technique, and inversion of refraction data applied travel time tomographic technique that using SIRT method. Also, could establish initial information in model variable and improved the result of inversion by restricting model parameter value and dimension of area. Confirmed efficient fact in sequence and velocity structure grasping by utilizing accurate initial velocity model made out on the basis of marine reflection data, and mixed exploration technique using reflection and refraction have propriety that can trust in field application.

• Nuclear Engineering and Technology
• /
• v.51 no.5
• /
• pp.1231-1240
• /
• 2019

Unlike land-based nuclear power plants, a marine or floating reactor is affected by external forces due to ocean conditions. These external forces can cause additional accelerations and affect each system and equipment of the marine reactor. Therefore, in designing a marine reactor and evaluating its performance and stability, a thermal hydraulic safety analysis code is necessary to consider the thermal hydrodynamic effects of ship motion. MARS, which is a reactor system analysis code, includes a dynamic motion model that can simulate the thermal-hydraulic phenomena under three-dimensional motion by calculating the body force term included in the momentum equation. In this study, it was verified that the dynamic motion model can simulate fluid motion with reasonable accuracy using conceptual problems. In addition, two modifications were made to the dynamic motion model; first, a user-supplied table to simulate a realistic ship motion was implemented, and second, the flow regime map determination algorithm was improved by calculating the volume inclination information at every time step if the dynamic motion model was activated. With these modifications, MARS could simulate the thermal-hydraulic phenomena under ocean motion more realistically.

• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.7
• /
• pp.743-751
• /
• 2013

In this paper, an approach to deal with model uncertainty using norm-optimal iterative learning control (ILC) is mentioned. Model uncertainty generally degrades the convergence and performance of conventional learning algorithms. To deal with model uncertainty, a worst-case norm-optimal ILC is introduced. The problem is then reformulated as a convex minimization problem, which can be solved efficiently to generate the control signal. The paper also investigates the relationship between the proposed approach and conventional norm-optimal ILC; where it is found that the suggested design method is equivalent to conventional norm-optimal ILC with trial-varying parameters. Finally, simulation results of the presented technique are given.

• Proceedings of KOSOMES biannual meeting
• /
• 2017.04a
• /
• pp.95-95
• /
• 2017

• Proceedings of KOSOMES biannual meeting
• /
• 2018.06a
• /
• pp.161-161
• /
• 2018