• Journal of the Korean earth science society
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• v.36 no.4
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• pp.367-389
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• 2015

This study developed an experimental program for mapping temperature and salinity distribution around the Korean marginal seas using Ocean Data View (ODV) software. Serial ocean observational data have been analyzed after being converted to the ODV compatible format using a separated program newly developed for this study. When this new experimental program was applied to 65 pre-service teachers, it was found that the quality of assignment completion with a new program improved compared with that of the same group who used the existing program. A questionnaires was employed to delve into participants' satisfaction of the new program. Findings depicted that accurate and quick drawing of isoline drew the highest responses of satisfaction, and confirmed positive responses to the understanding and application of this new experimental program.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.50-57
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• 2005

Ice resistance on ice-transiting vessels is one of th￡ important issues concerning th￡ design of ships with ice classes. In this study, th￡ development of GUI software for estimation of ice resistance on ice-transiting vessels is discussed. lee resistance estimation equations, based on model tests and full-scale sea trial data from many previous research articles, are studied in conjunction with two ship categories i.e., ,icebreakers/supply/tug vessels and ice-strengthened cargo vessels. lee resistance estimation equations are summarized in common format and are compared with each other. The GUI software 'Ice View,' written in MS Visual Basic language, can calculate ice resistances according to varying ice thickness and ship speed. The software can provide the calculated results, with suitable tables and graphs, for easy comparison of each ice resistance estimation equation.

• Journal of Power System Engineering
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• v.20 no.2
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• pp.79-84
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• 2016

The thermodynamic performance of ocean thermal energy conversion with 1 kg/s geothermal water flow rate as a heat source was evaluated to obtain the basic data for the optimal design of cycle with respect to the classification of the working fluid. The basic thermodynamic model for cycle is rankine cycle and the geothermal water and deep seawater were adapted for the heat source of evaporator and condenser, respectively. R245fa, R134a are better to use as a working fluid than others in view of the use of geothermal water. It is important to select the proper working fluid to operate the ocean thermal energy conversion. So, this paper can be used as the basic data for the design of ocean thermal energy conversion with geothermal water and deep seawater.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.105-112
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• 2006

Freak waves in the ocean are recently drawing much attention as a natural disaster to ocean structures and navigating ships as well. Several observation data, among them the Draupner New Year Wave, show the very impressive feature of Freak waves whose wave height is up to three times as high as the significant wave height of surrounding waves, In addition, Freak wave appears as an isolated very high crest in somewhat stationary random waves of same order in their wavelengths. Bearing such characteristics in mind, one notices its extraordinary steepness. This strongly suggests that Freak wave is not long lived but transient nature on the whole. A great number of studies to explain these natures were published from both theoretical and numerical point of view. However it is not sure if they are applicable to actual ocean environment. In this paper, we deal with the results concerning abnormal and/or Freak waves from in-situ ocean wave data and point out several remarks to the problems lain behind the contributions in this context. A physical experiment is described to reinforce the subject discussed from the observation data.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.245-246
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• 2014

This paper suggests the navigation information display system which is based on augmented reality technology and especially focuses on image analysis technology. Navigator has to always confirm the information from marine electronic navigation devices and then they compare with the view of outside targets of the windows. During this 'head down' posture, they feel uncomfortable and sometimes it cause near-accidents such as collision or missing objects, because he or she cannot keep an eye on the front view of windows. Augmented reality can display both of information of virtual and real in a single display. Therefore we tried to adapt the AR technology to help navigators and have been studied and developed image pre-processing module as a previous research already. To analysis the outside view of the bridge window, we have extracted navigational information from the camera image by using image processing. This paper mainly describes about recognizing ship feature by haar-like feature and filtering region of interest area by AIS data, which are to improve accuracy of the image analysis.

• International Journal of Ocean System Engineering
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• v.1 no.3
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• pp.155-164
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• 2011

The second-order motion characteristics of a semi-submersible are investigated in regular waves. A higher-order boundary element method in a frequency domain and a finite element method in a time-domain were applied to the numerical analysis of the nonlinear hydrodynamic force and motion characteristics of semi-submersibles in view point of potential flow. Various aspects of nonlinear effects on the heave and roll of a semi-submersible were numerically investigated and some selected cases were compared with the model test data.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.2
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• pp.208-216
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• 2014

In case of any coastal ocean near the mouth of huge rivers, low salinity water can be formed due to its large amount of freshwater discharge. For the acoustic analysis on the low salinity environment, some oceanographic data of the East China Sea and the Atlantic Ocean were collected through KODC (Korea Oceanographic Data Center) and NODC (National Oceanographic Data Center) online service. In this paper, the T-S gradient diagram is introduced to show a relation between the gradients of temperature and salinity in view of acoustic surface channel formation. Existence of haline channel, quantitative contribution of gradients of salinity and temperature, effectiveness of the channel formation can be known by the T-S gradient diagram. After applying the collected data into the diagram, tropical regions of the Atlantic Ocean show strong haline channel due to its nearly invariant temperature and drastic change of salinity with depth. The averaged transmission loss in the channel is about 5.7 ~ 7.5 dB less than that out of the channel by the results of acoustic propagation model (RAM: Range independent Acoustic Model). On the other hand, the East China Sea and temperate region of the Atlantic ocean have weaker haline channel with less difference of the averaged transmission loss between in and out of the channel as 3.2 ~ 6.0 dB. Although data samples used in this study have limitation to represent the general physical structures of the three ocean regions, the T-S gradient diagram is shown to be useful and acoustic field affected by low salinity environment is investigated in this study.

• Korean Journal of Remote Sensing
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• v.26 no.2
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• pp.175-188
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• 2010

A new correction method is required for the Geostationary Ocean Color Imager (GOCI), which is the world's first ocean color observing sensor in geostationary orbit. In this paper we introduce a new method of atmospheric and the Bidirectional Reflectance Distribution Function(BRDF) correction for GOCI. The Spectral Shape Matching Method(SSMM) and the Sun Glint Correction Algorithm(SGCA) were developed for atmospheric correction, and BRDF correction was improved using Inherent Optical Property(IOP) data. Each method was applied to the Sea-Viewing Wide Field-of-view Sensor(SeaWiFS) images obtained in the Korean sea area. More accurate estimates of chlorophyll concentrations could be possible in the turbid coastal waters as well as areas severely affected by aerosols.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.5
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• pp.330-337
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• 2022

Research on object detection algorithms using 2D data has already progressed to the level of commercialization and is being applied to various manufacturing industries. Object detection technology using 2D data has an effective advantage, there are technical limitations to accurate data generation and analysis. Since 2D data is two-axis data without a sense of depth, ambiguity arises when approached from a practical point of view. Advanced countries such as the United States are leading 3D data collection and research using 3D laser scanners. Existing processing and detection algorithms such as ICP and RANSAC show high accuracy, but are used as a processing speed problem in the processing of large-scale point cloud data. In this study, PointNet a representative technique for detecting objects using widely used 3D point cloud data is analyzed and described. And RandLA-Net, which overcomes the limitations of PointNet's performance and object prediction accuracy, is described a review of detection technology using point cloud data was conducted.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.3
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• pp.140-151
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• 2020

It is important to identify the location of ship hull blocks with exact block identification number when scheduling the shipbuilding process. The wrong information on the location and identification number of some hull block can cause low productivity by spending time to find where the exact hull block is. In order to solve this problem, it is necessary to equip the system to track the location of the blocks and to identify the identification numbers of the blocks automatically. There were a lot of researches of location tracking system for the hull blocks on the stockyard. However there has been no research to identify the hull blocks on the stockyard. This study compares the performance of 5 Convolutional Neural Network (CNN) models with multi-view image set on the classification of the hull blocks to identify the blocks on the stockyard. The CNN models are open algorithms of ImageNet Large-Scale Visual Recognition Competition (ILSVRC). Four scaled hull block models are used to acquire the images of ship hull blocks. Learning and transfer learning of the CNN models with original training data and augmented data of the original training data were done. 20 tests and predictions in consideration of five CNN models and four cases of training conditions are performed. In order to compare the classification performance of the CNN models, accuracy and average F1-Score from confusion matrix are adopted as the performance measures. As a result of the comparison, Resnet-152v2 model shows the highest accuracy and average F1-Score with full block prediction image set and with cropped block prediction image set.