• 한국군사과학기술학회지
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• 제5권2호
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• pp.169-184
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• 2002

In order to extract bearing information from the directional sensors of DIFAR(directional frequency analysis and recording) that is a kind of passive sonobuoy, the cardioid beamforming algorithm applicable to DIFAR system was studied in the frequency domain. the algorithm uses narrow-band signals propagated though the media from the acoustic sources such as ship machineries. The proposed algorithm is expected to give signal to noise ratio of 6dB when it uses the maximum response axis(MRA) among the Cardioid beams. The estimated bearings agree very well with those from GPS data. Assuming the bearings from GPS data to be real values, the estimation errors are analyzed statistically. The histogram of estimation errors in each frequency have Gaussian shape, the mean and standard deviation dropping in the ranges -1.1~$6.7^{\circ}$ and 13.3~$43.6^{\circ}$, respectively. Estimation errors are caused by SMR degradation due to propagation loss between the source and receiver, daily fluctuating geo-magnetic fields, and non-stationary background noises. If multiple DIFAR systems are employed, in addition to bearing, range information could be estimated and finally localization or tracking of a target is possible.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 Asia Navigation Conference
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• pp.123-128
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• 2006

This paper presents the design of a surveillance night vision system for marine ships. Both a hardware system and software modules for tracking control are developed. In order to control each control axis with compensation for ship motion, the two-degree of freedom(TDF) PID controller is designed and its parameters are tuned using a real-coded genetic algorithm(RCGA). Simulation demonstrates the effectiveness of the proposed system.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.343-348
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• 2006

Number of researches on efficient terminal operation system applying RFID(Radio Frequency Identification) are on progress. However, RFID has limitations on tracking and providing accurate positions of containers. In this paper, to enhance the performance of the integrated terminal operation system, an efficient loading management of yard is proposed by applying RFID-based RTLS(Real Time Locating System) that provides real-time accurate positions of containers. We found that a group-based sequence system is more efficient than the existing individual sequence number system in the container yard. In the group-based sequence system, the containers in the same group should have similar characteristics such as port of destination(POD), size, weight, etc. In order to run this system, we have proposed the parameters to the unspecified N bytes of RFID tag which are specified in ISO 18000-7. And, this paper proposed a development of integrated operation system of container terminal using RFID for reducing the ship turnaround time in ubiquitous port environment.

• 한국항해학회지
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• 제18권4호
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• pp.33-47
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• 1994

On developing port system, the performance tests of system in relation to ship maneuver generally consists of the three parts: the channel transit, the manoeuvring in a turning basin and the docking/undocking. The quantifications of risk of an accident has priviously been difficult due to the low occurrence of accidents relative to the number of transits. Additionally, accident statistics could not be related port system because of the large number of factors contributing to the accident. such as human error, equipment failure, visibility, light, traffic. etc. In case of the channel transit, "Relative Risk Factor(RRF)" or "Relative Risk Factor for Meeting Traffic" was proposed as the as the measures derived to quantify the relative risk of accident by M.W.Smith. This factor measure the tracking performance, the turning performance and the passing performance at meeting traffic. On the other hand, the safety of berthing maneuver is not measured with a few evaluating factors as controlled due to complex controllabilites such as steering, engine, side thrusters or tugs. This work, therefore, aims to propose the evaluating measure by the Analytic Hierarchy Process(AHP). Six experimental scenarios were establised under the various environmental conditions as independent variables. In every simulation, the difficulty of maneuver was scored by captain and compared with AHP scores. The results show almost same and from which the weights of eight evaluating factors could be fixed. Additionally, the limit value of relative factor in berthing safety to six scenarios could be estimated to 0.11.e estimated to 0.11.

• 한국산학기술학회논문지
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• 제21권8호
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• pp.334-341
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• 2020

훈련함 탐색레이더 최대 탐지거리 측정 운용시험평가 수행 중 탐색레이더 표적의 속도 및 침로 불안정 현상이 발생하여 표적에 대한 속도가 불안정하여 ◯◯knots로 접근하는 함정의 속도 편차가 ± 10knots 이상으로 정확한 표적 정보 산출이 불가하고 정보 불일치로 무장 교전 시 명중률 저하 및 표적관리 정확도 저하를 해결하기 위하여 속도 불안정 현상 개선에 대한 연구를 수행하였다. 이를 위해 4M1E에 근거한 Fishbone Diagram을 이용하여 9가지의 원인을 식별하였으며 가장 큰 원인으로 탐색레이더의 표적 처리 소프트웨어의 표적 처리 알고리즘으로 분석되었다. 본 연구에서는 기존 속도 산출 알고리즘을 검토하였으며, 표적 속도 불안정 현상의 원인이 되는 속도 안정화 필터 알고리즘과 안테나 회전수와의 영향성 검토를 수행하여 안테나 회전수 변경시 달라지는 𝜶, 𝞫값을 적용하지 못하는 문제점을 발견하여 이를 개선한 속도 안정화 필터 알고리즘을 표적 추적 관리 소프트웨어에 적용하였다. 본 개선사항에 대한 실선 시험을 통해 안테나 회전수 변경시에도 탐색레이더 표적 속도 정보가 일정하게 유지되는 개선 효과를 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.263-268
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• 2000

본 논문에서는 고조파 소음을 내는 시스템의기본 주파수 추정을 통한 새로운 피드백 능동소음제어 방법을 제안한다. 기존신호를 측정하기 어려운 상황에서 종래의 다중 정현파 소음의 능동제어 방법은 기준신호를 측정하는 대신 추정된 주파수를 이용하여 기준신호를 만들어낸다. 그러나 비팅현상(beating phenomenon)이 존재할 때는 순간적으로 특정 주파수 성분이 사라지게 되므로 적응 주파수 추정이 어렵게 되어 비팅현상에 의한 주파수 추정에서의 혼돈을 만들어진 기준신호를 쓸모없게 만든다. 제안된 알고리즘은 두 가지 부분으로 구성된다. 첫째는 기본주파수 추정을 이용한 기준신호 발생기이고 둘째는 기존의 피드포워드 제어부분이다. 제안된 결정 규칙을 이용한 기본주파수 추정알고리즘은 비팅현상에 둔감할 뿐 아니라 기존의 직렬형 적응노치필터 방법에 비해 좋은 추종성능과 적은 주파수 추정 오차의 분산을 갖는다. 더욱이 신호대잡음비가 좋지 않아 기존의 주파수 검증하기 위해서 실측한 선박의 객실 소음과 자동차의 시변하는 엔진부밍소음에 대해서 모의 실험을 수해한다.

• 소음진동
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• 제10권6호
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• pp.1059-1066
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• 2000

본 논문에서는 고조파 소음을 내는 시스템의 기본 주파수 추정을 통한 새로운 피드백 능동소음제어 방법을 제안한다. 기준신호를 측정하기 어려운 상황에서 종래의 다중 정현파 소음의 능동제어 방법은 기준신호를 측정하는 대신 추정된 주파수를 이용하여 기준신호를 만들어낸다.$^{(4)}$ 그러나 맥놀이현상(beating phenomenon)이 존재할 때는 순간적으로 특정 주파수 성분이 사라지게 되므로 적응 주파수 추정이 어렵게 되어 맥놀이현상에 의한 주파수 추정에서의 혼돈은 만들어진 기준신호를 쓸모없게 만든다. 제안된 알고리즘은 두 가지 부분으로 구성된다. 첫째는 기본주파수 추정을 이용한 기준신호 발생기이고 둘째는 기존의 피드포워드 제어 부분이다. 제안된 결정 규칙을 이용한 기본주파수 추정알고리즘은 맥놀이현상에 둔감할 뿐 아니라 기존의 직렬형 적응노치필터 방법에 비해 좋은 추종성능과 적은 주파수 추정 오차의 분산을 갖는다.$^{(4)}$ 더욱이 신호대잡음비가 좋지 않아 기존의 주파수 추정방법으로는 추정될 수 없는 주파수 성분가지 제어가 가능하다. 제안된 능동소음제어 방법의 성능을 검증하기 위해서 실측한 선박의 객실 소음과 자동차의 시변하는 엔진부밍소음에 대해서 모의 실험을 수행한다.

• 제어로봇시스템학회논문지
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• 제8권9호
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• pp.776-787
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• 2002

Automation of welding process in shipyards is ultimately necessary, since the welding site is spatially enclosed by floors and girders, and therefore welding operators are exposed to hostile working conditions. To solve this problem, a welding mobile robot that can navigate autonomously within the enclosure has been developed. To achieve the welding task in the closed space, the robotic welding system needs a sensor system for the working environment recognition and the weld seam tracking, and a specially designed environment recognition strategy. In this paper, a three-dimensional laser vision system is developed based on the optical triangulation technology in order to provide robots with 3D work environmental map. Using this sensor system, a spatial filter based on neural network technology is designed for extracting the center of laser stripe, and evaluated in various situations. An environment modeling algorithm structure is proposed and tested, which is composed of the laser scanning module for 3D voxel modeling and the plane reconstruction module for mobile robot localization. Finally, an environmental recognition strategy for welding mobile robot is developed in order to recognize the work environments efficiently. The design of the sensor system, the algorithm for sensing the partially structured environment with plane segments, and the recognition strategy and tactics for sensing the work environment are described and discussed with a series of experiments in detail.

• Ocean and Polar Research
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• 제42권3호
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• pp.211-223
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• 2020

With the increasing demand for improved marine environments and safety, greater ability to minimize damages to coastal areas from harmful organisms, ship accidents, oil spills, etc. is required. In this regard, an accurate assessment and understanding of current systems is a crucial step to improve forecasting ability. In this study, we examine spatial and temporal characteristics of current systems in the adjacent seas of Jeju Island using a high-resolution regional ocean circulation model. Our model successfully captures the features of tides and tidal currents observed around Jeju Island. The tide form number calculated from the model result ranges between 0.3 and 0.45 in the adjacent seas of Jeju Island, indicating that the dominant type of tides is a combination of diurnal and semidiurnal, but predominantly semidiurnal. The spatial pattern of tidal current ellipses show that the tidal currents oscillate in a northwest-southeast direction and the rotating direction is clockwise in the adjacent seas of Jeju Island and counterclockwise in the Jeju Strait. Compared to the mean kinetic energy, the contribution of tidal current energy prevails the most parts of the region, but largely decreases in the eastern seas of Jeju Island where the Tsushima Warm Current is dominant. In addition, a Lagrangian particle-tracking experiment conducted suggests that particle trajectories in tidal currents flowing along the coast may differ substantially from the mean current direction. Thus, improving our understanding of tidal currents is essential to forecast the transport of marine pollution and harmful organisms in the adjacent seas of Jeju Island.

• 대한임베디드공학회논문지
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• 제12권5호
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• pp.295-301
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• 2017

Recently, autonomous navigation technology, obstacle recognition, and obstacle collision avoidance technology are actively being developed for an unmanned surface vehicle (USV). The path to move from the current location to the destination should be planned, in order for an USV to autonomously operate safely to its destination. The dynamic window approach (DWA) is a well-known navigation scheme as a local path planning. The DWA algorithm derives the linear velocity and angular velocity by evaluating the destination direction, velocity, and distance from the obstacle. However, because DWA algorithm does not consider tracking the path, when using only the DWA algorithm, the ship may navigate away from the path line after avoiding obstacles. In this paper, we propose an improved DWA algorithm that can follow path line. And we implemented the simulation and compared the existing DWA algorithm with the improved DWA algorithm proposed in this paper. As a result, it is confirmed that the proposed DWA algorithm follows the path line better.