• Journal of Advanced Navigation Technology
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• v.16 no.1
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• pp.122-130
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• 2012

Airborne separation assurance is a key requirement for Free Flight. This paper is to propose autonomous flight algorithm, such as extended authority of delegation, efficiency of airspace issue to deal with the empirical solution for free flight, and to measure flight efficiency and conflict detection and resolution (CD&R) by utilizing flight performance data under the two circumstances of scenario with the modeling of proposed algorithm and potential field algorithm. The results show that the autonomous flight algorithm is superior to the potential field algorithm under the circumstances of free flight airspace in terms of algorithm performance, CD&R, and flight efficiency.

• Proceeding of EDISON Challenge
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• 2016.11a
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• pp.35-43
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• 2016

본 연구에서는 EDISON의 해석자를 활용하여 선박의 최적 운항 자세 도출과 같은 실용적 문제 해석뿐 만 아니라 자유 수면 및 대칭 경계 조건이 수직한 몰수 익형 주위 유동에 미치는 영향을 분석하는 학술적 연구를 수행하였다. 선박의 자세에 따른 저항 변화를 분석한 결과 0.5m 선수 트림에서 선체 저항이 가장 작은 것으로 나타났으며, 이는 유동 가속에 의한 선수 어깨부의 낮은 압력 및 선미부에서의 압력 회복에 의한 것이다. 반면, 1.0m 선미 트림에서 선체 저항이 가장 큰 것으로 나타났는데, 평형 상태보다 선미부의 압력 회복이 약하기 때문이다. 또한 자유 수면과 대칭 경계 조건이 날개 성능에 미치는 영향을 분석한 결과, 비현실적 대칭경계 조건으로 인해 날개 양력이 13%~16% 크게 나타났으므로 대칭경계조건을 사용할 경우에는 이러한 오차를 감안해야 한다.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.5
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• pp.60-67
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• 2003

For risk or reliability assessment of ship structures against particular hazardous situations such as total loss or sinking due to hull girder collapse, the short-term based response analysis rather than the long-term response analysis is required to determine wave-induced bending moments when the ship encounters a storm of specific duration and with a specified small encounter probability. In the present study, the effects of operational condition and sea states on wave-induced bending moments of large merchant vessels are investigated. A series of the short-term response analyses for a hypothetical VLCC and a Capesize bulk carrier (CSBC) are carried out with varying operational condition and sea states which include ship speed, significant wave height and wave persistence time, using the linear-strip theory based program ABS/SHIPMOTION and the MIT sea-keeping tables. The computed results are also compared with the IACS design formula predictions. The results and insights developed from the present study are summarized.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.197-203
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• 2012

In this paper, study the substantial issues which occurs upon free flight environment by performing separation assurance under multiple conflict(over 3 Aircraft), recovery en route under the terms of time constrains and fixed way point after the conflict avoidance, correlations between conflict detection distance and separation assurance by utilizing Autonomous flight algorithm. Result of this experiment demonstrates that the extension of detection distance is advantageous to solution of separation assurance and enhancing of flight efficiency, choose to maneuver by applying time constrain terms and fixed way point according to the situation of conflict prediction in case of recovery maneuver after the conflict avoidance. And separation assurance can be solved by applying 2 degrees or more of bank angle. When choosing the optimal bank angle could be drastically improved flight efficiency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.508-510
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• 2021

As the international standardization of 5G element technologies (e.g., 5G vertical satellite, direct communication functions between 5G NR (New Radio)-based devices) required not only in 5G verticals but also in autonomous navigation services is currently underway, it is expected to be utilized for autonomous navigation services while utilizing the economic size advantages of the scale of international standard-based solutions through 3GPP international standardization of marine communication services related to autonomous navigation vessels. In order to establish the ecosystem of ICT convergence market related to autonomous navigation vessels and to preoccupy core communication technology based on international standards, it is necessary to develop digital communication systems and gateways that have global compatibility, (2) secure core element technology based on next generation communication, and (3) promote international standardization for internationalization of related technologies. For this, data analysis and standard technology should be developed through service analysis by distance. Currently, the requirements for the operation of autonomous navigation vessels can be classified into three categories.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.5
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• pp.558-570
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• 2015

A study on the green ship design for Ultra Large Container Ship (ULCS, 18,000 TEU Class Container Ship) was performed based on the four step procedures of the initial design and hull form optimization to maximize economic and propulsive performance. The first, the design procedure for ULCS was surveyed with economic evaluation considering environmental rules and regulations. The second, the characteristics of single and twin skeg container ships were investigated in view of initial design and performances. The third, the hull form optimization for single and twin skeg ships with the same dimensions was conducted to improve the resistance and propulsive performances at design draught and speed by several variations and the results of the optimization were verified by numerical calculations of CFD and model test. The last, for the estimated operating profile of draught and speed, the hull forms of single and twin sked ships were optimized by CFD. From this study, the methodologies to optimize the hull form of ULCS were proposed with considerations during the green ship design and the improvement of the energy efficiency for the optimized hull forms was confirmed by the proposed formula of the total energy considering design conditions, operating profile and fuel oil consumption.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.369-370
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• 2022

최근 자율 운항 선박에 대한 관심이 높아지고 있다. 특히, MUNIN (Maritime Unmanned Navigation through Intelligence in Networks) 프로젝트를 계기로 자율 운항 선박에 대한 개발과 연구가 활발히 진행되고 있다. 또한 국제해사기구 IMO는 자율 운항 선박 시대에 대응하기 위해 자율 선박을 MASS (Maritime Autonomous Surface Ship)라 정의하고 선박 자율화 정도에 따라 4단계 등급을 제시하고 있다. 완전한 자율 운항 선박에 대한 요구조건을 만족하기 위해서는 항로 결정과 제어기술이 필수적이다. 본 연구에서는 여러 가지 기술 중 선박의 최적경로를 생성하는 기법을 다룬다. 기존에 최적항로를 생성하기 위한 방법으로는 A^*, Dijkstra와 같은 알고리즘들이 주로 사용되었다. 그러나 이와 같은 알고리즘은 섬이나 육지에 대한 충돌 회피는 고려하고 있지만 수심 및 연안 선박에 대한 규정들은 고려하지 않고 있어 실제로 적용하기에는 한계점이 있다. 따라서 본 연구에서는 안전을 위해 선박의 선저 여유 수심과, 해도에 규정되어 있는 선박 운항에 대한 여러 규정들을 반영하여 최적 항로를 생성하고자 한다. 최적 항로를 생성하기 위한 알고리즘으로는 강화학습 기반의 Q-learning 알고리즘을 적용하였다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.25 no.4
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• pp.161-169
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• 2017

The Human Factors Analysis and Classification System (HFACS) is a general human error framework originally developed and tested within the U.S. military as a tool for investigating and analyzing the human causes of aviation accidents. Based upon Reason's (1990) model of latent and active failures, HFACS addresses human error at all levels of the system, including the condition of aircrew and organizational factors. As a result, this study aims to examine the influence between the latent conditions based on HFACS. This study seeks to verify the factors of "Organizational Influence" effecting the "Precondition for Unsafe Acts" of HFACS. The results of empirical analysis demonstrated that the organizational influence had a positive influence on precondition for unsafe act, especially the "Organizational Climate" of organizational influence had even greater influence on precondition for unsafe acts.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.4
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• pp.56-64
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• 2014

There were a total of 65 accidents of helicopers between 1990 and 2013. The overall accidents rate has remained around 8 accidents per 100,000 flight hours, and the fatal rate has stayed at about 8 accidents per 100,000 flight hours. In this study, we conduct a series of statistical analyses to investigate the significance of latent failure of groups that operate the helicopter. Analysis of variance demonstrated significant differences in the latent condition score for the 3 groups, with the lower accidents rate groups reporting better scores of latent condition. Results indicated that there are the significant differences of latent condition in accidents between groups of high accidents rate and groups of low accidents rate.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.588-592
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• 2016

선박의 최적 운항 자세를 찾기 위해 자유 수면을 포함한 저항 해석을 수행할 경우 많은 격자를 이용한 비정상 해석으로 인해 계산 시간이 오래 소요되는 단점이 있다. 본 연구에서는 이를 개선하여 이중 모형을 이용한 정상 해석을 통해 보다 효율적으로 선박의 최적 운항 자세를 도출하는 방법을 연구하였다. KCS를 대상선으로 선정하여 설계속도(24knots)와 저속(15knots)인 경우에 대하여 평형 상태 및 선수/선미 트림 상태에서 이중 모형 수치해석을 수행하고 기존의 연구결과와 비교하였다. 그 결과 자유수면 유무와 속도에 상관없이 선체 자세에 따른 저항 값은 동일한 경향을 갖는 것을 확인하였다. 하지만 저속일 경우 트림조건에 따른 저항의 변화의 폭에서 차이를 보였으며, 이는 압력저항에 기인한 것이다. 따라서 이중 모형을 이용한 저항 해석은 압력저항의 변동이 큰 경우에는 적용되기 어렵다는 한계점이 있다. 하지만 마찰 저항이 주요한 경우에 적용되어 계산효율을 획기적으로 높일 수 있으며, 정성적인 경향을 제시할 수 있는 타당한 방법이라 사료된다.