• Journal of the Korean Institute of Navigation
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• v.24 no.3
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• pp.123-132
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• 2000

In order to improve the ship maneuverability, It is important to estimate precisely the hydrodynamic coefficients of added mass forces acting on a ship especially in shallow waters, and simple methods for predicting such hydrodynamic forces Is also very desirable. In the previous paper using 3-Dimension potential flow theory, it has been demonstrated that potential calculation is available to estimate added mass coefficients. The present work is aimed at the suggestion of the simplified formulas for predicting the translation and lateral motion of added mass coefficients in shallow water. So, 3-D potential flow theory is also used to calculate the added mass coefficients in deep and shallow waters for Series 60 model which has 5 different kinds of block coefficients (0.6-0.8), SR196 model and T/S HANNARA. After some series computation, simplified formulas for Predicting the added mass force in shallow waters is suggested based on the computation results of Series 60 model. The formulas consist of the combination of principal dimensions and the water depth; d/B, Cb, d/H. The predicted results are compared with the Computation results for SR196 model and T/S HANNARA. The precision of predicted results by simplified formulas are good enough for the practical use. (d/B : draft-Breadth ratio, d/H draft-Water depth ratio, Cb : Block coefficients).

• Journal of Navigation and Port Research
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• v.29 no.3 s.99
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• pp.257-262
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• 2005

Environmental problems and safety problems in coastal area is one of the most important factors for designing coastal structures and maintaining facilities in coastal zone. And thus study on Wave transformation around coastal area is very important to develope a new port or on industrial area. Delft 3D-WAVE is applied to Ulsan new port area and the culculated results are analysed and compared with measured data Delft 3D-wave module is based on SWAN model which considers wave shoaling and refraction for irregular wave. This module also covers wind effect, bottom friction. white-capping and wave breaking effect. The results of this study show a good agreement with measured data and thus Delft 3D-WAVE module can be applied to simulate irregular wave transformation in coastal area.

• Journal of Advanced Navigation Technology
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• v.5 no.2
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• pp.123-133
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• 2001

The existing visualization methods using the satellite images or map images require complicated preprocessing stages and a large amount of visual data to represent the 3-D terrain. This paper presents a 3-D visualization method for geographical information, which enables automatic generation of 3-D terrain. It is generated based, on contour information obtained from a numerical map. This paper also introduces a method that resolves the three main problems needed to visualize 3-D terrain from contour lines such as correspondence, tiling, and branching. The virtual contour line is defined to extend a distorted contour line to have a similar shape to the corresponding contour line that is used, to generate 3-D surfaces. It helps that 3-D terrain is represented exactly and in detail.

• Journal of IKEEE
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• v.16 no.2
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• pp.69-75
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• 2012

In this paper, microstrip array antenna is proposed for the wireless communication of DSRC(dedicated short range communication) scheme at 5.8GHz, which works as a part of the Navigation terminal. The microstrip patches minimized from a rectangular microstrip antenna with a half wavelength are arrayed to be mounted on the narrow and long area in the top side of the navigation terminal. Besides, the array antenna can limit its own beamwidth to the driving lane and has better directivity. It is simulated to verify the validity of the proposed application. The prototype fabricated has a volume of $18{\times}40{\times}0.8mm^3$. From the measurement, it has circular polarization performance of 4dB axial ratio over 40MHz frequency band. In addition, antenna gain of 6.2dBi and 3dB beamwidth of $70^{\circ}$ at cross section of driving lane have been achieved.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.3
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• pp.281-287
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• 2023

Establishing a ship's passage plan is an essential step before it starts to sail. The research related to the automatic generation of ship passage plans is attracting attention because of the development of maritime autonomous surface ships. In coastal water navigation, the land, islands, and navigation rules need to be considered. From the path planning algorithm's perspective, a ship's passage planning is a global path-planning problem. Because conventional global path-planning methods such as Dijkstra and A^* are time-consuming owing to the processes such as environmental modeling, it is difficult to modify a ship's passage plan during a voyage. Therefore, the D^* algorithm was used to address these problems. The starting point was near Busan New Port, and the destination was Ulsan Port. The navigable area was designated based on a combination of the ship trajectory data and grid in the target area. The initial path plan generated using the D^* algorithm was analyzed with 33 waypoints and a total distance of 113.946 km. The final path plan was simplified using the Douglas-Peucker algorithm. It was analyzed with a total distance of 110.156 km and 10 waypoints. This is approximately 3.05% less than the total distance of the initial passage plan of the ship. This study demonstrated the feasibility of automatically generating a path plan in coastal navigation for maritime autonomous surface ships using the D^* algorithm. Using the shortest distance-based path planning algorithm, the ship's fuel consumption and sailing time can be minimized.

• Journal of Navigation and Port Research
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• v.28 no.10 s.96
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• pp.875-879
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• 2004

In this paper, sub-harmonic pumped(SHP) mixer using anti-parallel diode pair(APDP) is designed for 5 GHz band wireless communication system. Conventional mixers mix LO with RF, and obtain IF signal from the difference between LO and RF. As the frequency increase, LO signal requires higher LO power, better phase noise characteristics, more stable La. However, using APDP, the SHP mixer mixes the 2nd harmonics of LO signal. Therefore, the SHP mixer has an advantage that the LO signal frequency required for IF signal is reduced at half value of LO fundamental frequency. When LO power is 3 dBm, the conversion loss of manufactured SHP mixer is 12.83 dB. The isolation of LO/IF, 2LO/IF, RF/1F and LO/RF is 39.17 dB, 58 dB, 34 dB, and 67.9 dB. respectively. For this case, IP3 at input is 8 dBm.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.10
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• pp.970-976
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• 2012

In this paper, a single LRF has been used to produce a 3D map for the mobile robot navigation. The 2D laser scanners are used for mobile robots navigation, where the laser scanner is applied to detect a certain level of area by the straight beam. Therefore it is limited to the usages of 2D obstacle detection and avoidance. In this research, it is designed to complement a mobile robot system to move up and down a single LRF along the yaw axis. During the up and down motion, the 2D data are stacked and manipulated to build a 3D map. Often a single LRF data are mixed with Gaussian and impulse noises. The impulse noises are removed out by the hybrid median filter designed in this research. The 2D data which are improved by deleting the impulse noises are layered to build the 3D map. Removing impulse noises while preserving the boundary is a main advantages of the hybrid median filter which has been used widely to improve the quality of images. The effectiveness of this hybrid median filter for rejecting the impulse noises has been verified through the real experiments. The performance of the hybrid median filter is evaluated in terms of PSNR (Peak Signal to Noise Ratio) and the processing time.

• Proceedings of the IEEK Conference
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• 2003.07d
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• pp.1519-1522
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• 2003

본 논문에서는 지리정보서비스 개념을 사이버 박물관 정보 서비스와 접목하여 구현하였다. 입체적인 지리정보를 활용하기 위해서 유물과, 유적에 대한 정보를 3D모델링 하였으며, 3D모델의 랜더링 최적화를 위해서 LOD(level of detial)를 적용하여 범용 PC의 유저(user) 누구나 쉽게 이용할 수 있다. 또한 사용자로 하여금 실시간 인터렉티브 기능을 부여하여 네비게이션(navigation)을 쉽게 구현하였다. 일반적으로 종래의 사이버 정보서비스의 멀티미디어매체가 수동적이고, 실감적인 효과가 떨어지는 단점을 보완하는 실시간 3차원 인터렉티브 컨텐츠를 제작 방법을 구현하였다.

• Journal of The Korean Radiological Technologist Association
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• v.29 no.1
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• pp.210-210
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• 2003

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.306-307
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• 2022

Recently, in the process of developing, verifying, and upgrading the e-Navigation service and autonomous navigation system, there is an increasing demand for inter-working with a ship-handling simulator that can simulate actual maritime traffic conditions. In this paper, to develop a ship-handling simulation system based on actual maritime traffic conditions, a simulation server was built, received information on the actual maritime traffic conditions from the e-Navigation linkage system, and changed to information for operating the ship-handling simulator. In order to provide simulation images to users, 3D shape modeling for trade ports, coastal ports in Korea and major type of ship were performed. The developed system will be used for the advancement of e-Navigation service, development and verification of autonomous navigation systems, by enabling simultaneous processing of more than 10,000 ships and allowing users to simulate actual maritime traffic conditions in the desired area.