• Journal of Korea Spatial Information System Society
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• v.11 no.1
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• pp.137-144
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• 2009

Understanding lane markings in a live video captured from a moving vehicle is essential to build services for intelligent vehicles such as LDWS(Lane Departure Warning Systems), unmanned vehicles, video-based car navigation systems. In this paper, we present a novel approach to recognize the color of lane markings and the lane number that he/she is driving on. More specifically, we present a background-color removal approach to understand the color of lane markings for various illumination conditions, such as backlight, sunset, and so on. In addition, we present a probabilistic network approach to decide the lane number. According to our experimental results, the proposed idea shows promising results to detect lane number in a various illumination conditions and road environments.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.5
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• pp.457-464
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• 2011

This paper deal with the validation of correction method of ice strength and thickness to the sea trial condition based on the ice model test results. It is very difficult to conduct the model test corresponding to the sea trial condition exactly. In addition, the available sea trial data is not sufficient for the validation of correction method. In the present study, the model test results of Terry-Fox ice breker have been used to compare the corrected results of sea trial test by varying its thickness and strength of model ice. The HSVA and ITTC methods have been applied to the present comparisions and the required power has been also validated by using the HSVA method. There are rather good agreement between the sea trial result and model test corrected by the HSVA and ITTC method. The more comparisons are expected to be carried out in near future.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.3
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• pp.107-115
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• 1995

A simple estimation system of ultimate and residual strength for ship structures is developed on the Open-Window system of SUN4 engineering workstation. System development consists of three stages. Firstly, various ultimate longitudinal strength estimation methods are investigated and some rational estimation methods are adopted based on the parametric comparison of various hulls or box girders. Secondly, these selected and newly formulated methods are linked with elastic & perfectly plastic section modulus calculation procedure. Therefore, the longitudinal hull girder strength can be calculated in the intact and damaged conditions due to the grounding or collision of hull structure. Finally, an exclusive system is developed such that whole procedures are proceeded under the window management system using mouse button and elastic and perfect plastic stress conditions. Also longitudinal members are plotted automatically under three dimensional graphic circumstances. These established program is tested for various actual ships, and some examples are illustrated.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.2
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• pp.1-10
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• 2002

Hull-propeller-rudder interactions are studied by the iterative computational procedures. Hull effects on the propeller are reflected through the effective velocities computed by the vortex ring method which used the measured nominal wake as input data. A potential based panel method has been developed to solve the propeller-rudder interactions using the obtained effective velocities. Steady flow characteristics around the rudder surface can be obtained by computing the induced velocities on the rudder by the propeller and vice versa are computed by the iterative manner until the converged solutions are obtained. Flow characteristics around the propeller and the rudder are measured by Laser Doppler Velocimetry(L.D.V.) in large cavitation tunnel at Samsung Heavy industries. The gap flow model is adopted to solve the characteristics of the horn rudder. Numerical results are compared with the experimental values and the computed velocity fields and pressure distributions with rudder angle on the horn rudder surface show good agreement with measured ones in large cavitation tunnel.

• Journal of Navigation and Port Research
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• v.35 no.8
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• pp.613-618
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• 2011

Vessels on anchoring are sometimes dragged due to the increased external forces. For preventing the dragging, it is required to enhance the holding power of the anchor. The holding power depends on the type and weight of the anchor and the seabed condition. Especially, the holding power of AC-14 type anchor is known to be 2~2.5 times bigger than that of ASS type anchor. However, these coefficients was determined nearly by the result of the model test, so there is a need to verify that by sea trial. Therefore actual dragging case was analyzed and then compared with the coefficients in use, it was found that the two of them are much alike.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.5
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• pp.291-297
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• 2013

Generally, form factor is determined through ITTC method. Determining the form factor from ITTC method includes the assumption that the form factor of a full-scale ship is the same value as its model ship. In other words, the form factor is independent on Reynolds number. However, for the more appropriate prediction of the resistance performance of a full-scale ship, the form factor must be determined with the consideration of the variation attendant on Reynolds number. In this research, several Geosim ship models are adopted to investigate the scale effect, and correlation lines of form factor are improved to suggest the better extrapolation method for the prediction of the form factor of full-scale ship. The corrected form factors using the correlation lines are compared with those determined from the results of low-speed resistance tests. To consider the influence of hull form, the correlation lines are determined for the group of high-speed ships and the group of low-speed ships, respectively. The corrected form factors have shown good agreement among the prediction results from each Geosim ship model to the full-scale ship.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.1
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• pp.35-44
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• 1990

Most of the medium-size ships are powered by large-bore, long-stroke, slow-speed and two-stroke diesel engines in order to improve the fuel efficiency. Such a propulsion plant develops low-frequency excitation forces/moments of significant magnitude. A RO/RO car/truck carrier is also one of the cases. In this paper, the rational methods for analysis of vertical and coupled horizontal-torsional vibrations are presented. Taking account of unusual characteristics of the hull form and structural systems, the emphasis is put on modelling methods based on beam analogy, calculation of system parameters such as added mass and its center, polar added-mass moment of inertia, shear coefficient of hull sections and coupling degree in antisymmetric modes, and modal analysis of forced vibrations.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.3
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• pp.379-385
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• 2012

This paper developes the navigation visual aid supporting a watch officer's situation awareness and analyzes its performance test result. Developing the equipment made from composite video sensor which transfer video signal, ranger laser measurement model which search out distance, Pan/ Tilt, center control device. The developed equipment with Pan/Tilt was made from high performance video sensor and ranger laser measurement. To make a real ship test, we carried on setting the developed equipment on ship, observed a danger factor and analyzed a image, and from that we can evaluate marine environment awareness. Through this result, the developed equipment can show effective ability of the awareness of the clearer check and resolution situation when compare with the binocular.

• Journal of Navigation and Port Research
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• v.39 no.4
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• pp.307-312
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• 2015

ARPA(Automatic Radar Plotting Aid) is a device to calculate CPA(closest point of approach)/TCPA(time of CPA), true course and speed of targets by vector operation of relative courses and speeds. The purpose of this study is to develop target acquisition and tracking technology for ARPA Radar implementation. After examining the previous studies, applicable algorithms and technologies were developed to be combined and basic ARPA functions were developed as a result. As for main research contents, the sequential image processing technology such as combination of grayscale conversion, gaussian smoothing, binary image conversion and labeling was deviced to achieve a proper target acquisition, and the NNS(Nearest Neighbor Search) algorithm was appllied to identify which target came from the previous image and finally Kalman Filter was used to calculate true course and speed of targets as an analysis of target behavior. Also all technologies stated above were implemented as a SW program and installed onboard, and verified the basic ARPA functions to be operable in practical use through onboard test.

• Journal of Navigation and Port Research
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• v.35 no.10
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• pp.805-810
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• 2011

An experiment was carried out to figure out the instantaneous flow characteristics in the wake of the transom stern's 2-dimensional section by 2-frame grey level cross correlation PIV method at $Re=3.5{\times}103$, $Re=7.0{\times}103$. The stern angles of models were learning at $45^{\circ}$(Model "A"), $90^{\circ}$(Model "B") and $135^{\circ}$(Model "C") respectively based on the survey results of real ships. The depth of wetted surface is 40mm from free surface. As Reynolds number increases, vortices increase in volume and move their way to the downstream. Flow separation appeared at the end of model's bottom.