• Journal of the Korean Institute of Navigation
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• v.13 no.3
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• pp.21-36
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• 1989

The submarine played an active part in military operation during the last of nineteenth century. Today, as an aid to science and technology and technology m the submarine is being utilized in the fields of deep sea investigation and sight-seeing as well as military activities. When the stability and the maneuverability of a submarine is studied, the problems arise on the vertical plane as well as the horizontal plane. However, the horizontal plane has been dealt with in the study of surface vessels. The author attempts to look into the hydrodynamic directional stability at high speeds (above 10knots) on the vertical plane, and to clarify the submarine's depth-rate as related to the factors that affect it : the distance from the center of buoyancy to the center of gravity, the speed of the submarine, and the position and the area ratio of hydroplane. In this study, the author considered the two groups of dimensionless derivatives of submarine. It is confirmed that the depth-rate of a submarine is decreased when the length, of BG is increased under the continuous submerging status. But the depth-rate is increased when the area ratio of hydroplane is enlarged. It is also confirmed that a submarine has only one critical speed in accordance with the shape of its hull, but unconcerned with its speeds.

• Journal of the Korean Geographical Society
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• v.41 no.5 s.116
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• pp.582-599
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• 2006

Due to the growing popularity of mobile information technology, more people, especially in the general public, have access to computerized geospatial information systems for wayfinding tasks or urban navigation. One of the problems with the current services is that, whether the users are exploring or navigating, whether they are travelers who are totally new to a region or long-term residents who have a fair amount of regional knowledge, the same method is applied and the direction are given in the same way. However, spatial knowledge for a given urban region expands in proportion to residency. Urban navigation is highly dependent on cognitive mental images, which is developed through spatial experience and social communication. Thus, the wayfinding service for a regional community can be highly supported, using well-known regional places. This research is to develop the framework for urban navigation within a regional community. The concept of communal ontology is proposed to aid in urban regional navigation. The experimental work was implemented with case study to collect regional landmarks, develop the ontological model and represent it with formal structure. The final product of this study will provide the geographical information of a region to the other agent and be the fundamental information structure for cognitive urban regional navigation.

• Journal of Navigation and Port Research
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• v.40 no.5
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• pp.241-247
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• 2016

The tracking filter plays a key role in the accurate estimation and prediction of maneuvering a vessel's position and velocity when attempting to enhance safety by avoiding collision. Therefore, in order to achieve accurate estimation and prediction, many oceangoing vessels are equipped with the Automatic Radar Plotting Aid (ARPA) system. However, the accuracy of prediction depends on the tracking filter's ability to reduce noise and maintain a stable transient response. The purpose of this paper is to derive the optimal values of the gain parameters used in tracking a High Dynamic Warship. The algorithm employs a ${\alpha}-{\beta}-{\gamma}$ filter to provide accurate estimates and updates of the state variables, that is, positions, velocity and acceleration of the high dynamic warship based on previously observed values. In this study, the filtering coefficients ${\alpha}$, ${\beta}$ and ${\gamma}$ are determined from set values of the damping parameter, ${\xi}$. Optimization of the damping parameter, ${\xi}$, is achieved experimentally by plotting the residual error against different values of the damping parameter to determine the least value of the damping parameter that results in the optimum smoothing coefficients leading to a reduction in the noise corruption effect. Further investigation of the performance of the filter indicates that optimal smoothing coefficients depend on the initial and average velocity of the target.

• Journal of Advanced Navigation Technology
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• v.25 no.5
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• pp.327-335
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• 2021

Navigational Aids Facilities help aircraft navigate by using wired communication, wireless communication, satellite, light, color and radio waves. Navigational Aids Facilities are used in all processes of aircraft operation, and if there is a problem with the facility, it may lead to delays in flight operation, cancellation of flights, and major airline accidents, resulting in enormous loss of life and property. In the management and operation of Navigational Aids Facilities, various outcomes will be brought about according to the advancement with the safety culture. The purpose of this study is to investigate the effect of advancement on safety culture in the operation of Navigational Aids facilities not only on members and customers, but also on benefits to bring to whole society. In this paper, the analysis results are presented using the structural equation model, and the meaning is presented in the conclusion.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.3
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• pp.174-182
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• 2013

The power wheelchair is an important and convenient mobility device. The demand of power wheelchair is increasing for assistance in mobility. In this paper we proposed a robotic wheelchair for mobility aid to reduce the burden from the disabled. The main issue in an autonomous wheelchair is the automatic detection and avoidance of obstacles and going to the pre-designated place. The proposed algorithm detects the obstacles and avoids them to drive the wheelchair to the desired place safely with panning scan from sensors of distance measurement and fuzzy control. By this way, the disabled will not always have to worry about paying deep attention to the surroundings and his path.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.1
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• pp.37-45
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• 2009

The power wheelchair is an important and convenient mobility device. The demand of power wheelchair is increasing for assistance in mobility. In this paper we proposed a robotic wheelchair for mobility aid to reduce the burden from the disabled. The main issue in an autonomous wheelchair is the automatic detection and avoidance of obstacles and going to the pre-designated place. The proposed algorithm detects the obstacles and avoids them to drive the wheelchair to the desired place safely with panning scan from sensors of distance measurement and fuzzy control. By this way, the disabled will not always have to worry about paying deep attention to the surroundings and his path.

• ETRI Journal
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• v.45 no.3
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• pp.479-491
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• 2023

The automation of agricultural machines is an irreversible trend considering the demand for improved productivity and lack of labor in handling agricultural tasks. Unstructured working environments and weather often inhibit a seemingly simple task from being fully autonomously performed. In this context, we propose a remote driving system (RDS) to aid agricultural machines designed to operate autonomously. Particularly, we modify a commercial speed sprayer for orchard environments into a robotic speed sprayer to evaluate the proposed RDS's usability and test three sensor configurations in terms of human performance. Furthermore, we propose a confidence error ellipsebased task performance measure to evaluate human performance. In addition, we present field experimental results describing how the sensor configurations affect human performance. We find that a combination of a semiautonomous line tracking device and a wide-angle camera is the most effective for spraying. Finally, we discuss how to improve the proposed RDS in terms of usability and obtain a more accurate measure of human performance.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.68-71
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• 2022

항로표지는 해상에 독립적으로 암초 위나 줄에 의해 떠 있는 형태로 존재하며, 선박들의 안전 운행에 필요한 다양한 정보를 제공하는 역할을 수행한다. 이러한 항로표지의 설치 및 동작 형태는 풍랑에 따라 기기의 위치가 가변적으로 변하게 된다. 따라서 기기의 위치가 급격하게 변했을 때, 항로표지 기기 내에도 영향을 받는다면 지방청의 항로표지 데이터 수신이 낮아질 것이라고 가설 설정했다. 본 논문에서는 기상특보에 따른 시간적 기준으로 구간을 나누어 풍랑과 항로표지 데이터 수신 간의 상관관계가 있는지 연구를 진행하였다. 연구 결과 풍랑이 거세질수록 평균 데이터 수집량이 감소하는 것으로 데이터 수신 강도의 영향을 줄 수 있음을 확인하였다. 이번 연구를 통해 풍랑에 대비한 항로표지 데이터의 개선이 필요하며, 선박의 안전과 관련된 만큼 정밀한 개선을 요한다.

• Journal of Navigation and Port Research
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• v.34 no.8
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• pp.603-607
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• 2010

The LORAN system had been used widely and it was an essential navigation aid for ships in the ocean until the GPS is adopted actively. In particular, it was essential functionality for the ships to sail the oceans. According to the advancement of industry, however, the current accuracy of traditional Loran is insufficient for the utilization of harbour approach, land navigation, and the field of survey and timing. Therefore it is necessary that the study on the improvement of the positioning accuracy of Loran. The one of the improving methods is to measure and compensate the propagation time delay between the transmitter and user's receiver, which is called as additional secondary factor (ASF). In this study, we measured the ASF between the Pohang master transmitting station (9930M) and four points where locate within 33 km apart from the transmitting station, using the measuring technique of the absolute time delay without a time of coincidence (TOC) table. As the result of measurement, the ranging error caused by the propagation delay was about 210 m at 33 km, however it can be reduced up to 40 m with ASF compensation.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.7
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• pp.130-135
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• 2004

This paper presents a 3-D localization of an autonomous underwater vehicle(AUV). Conventional methods of localization, such as LBL or SBL, require additional beacon systems, which reduces the flexibility and availability of the AUV We use a digital compass, a pressure sensor, a clinometer and ultrasonic sensors for localization. From the orientation and velocity information, a priori position of the AUV is estimated based on the dead reckoning. With the aid of extended Kalman filter algorithm, a posteriori position of the AUV is estimated by using the distance between the AUV and a mother ship on the surface of the water together with the water depth information from the pressure sensor. Simulation results show the possibility of practical application of the method to autonomous navigation of the AUV.