• 대한조선학회논문집
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• 제42권5호
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• pp.499-505
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• 2005

Underwater explosion shock response analysis of a nonlinear double resiliently mounted equipment on a MIL-S-901D Large floating Shock Platform(LFSP) was carried out using LS-DYNA3D/USA. As a nonlinear double resiliently mounted equipment, real main engine module of naval ship was considered, where the engine, bearing, and base frame including sound enclosure were treated as rigid bodies with six degrees of freedom. The nonlinear effects of resilient mounts on its shock response characteristics were examined, and the usefulness of our suggested method was also confirmed comparing with calculation results by the equipment maker.

• Journal of Ship and Ocean Technology
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• 제9권4호
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• pp.23-34
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• 2005

Increased usage of AUVs has led to the development of alternative navigational methods that use the acoustic beacons and dead reckoning. This paper describes a concurrent mapping and localization (CML) scheme that uses range sonars mounted on SNUUV­I, which is a small test AUV developed by Seoul National University. The CML is one of such alternative navigation methods for measuring the environment that the vehicle is passing through. In addition, it is intended to provide relative position of AUV by processing the data from sonar measurements. A technique for CML algorithm which uses several ranging sonars is presented. This technique utilizes an extended Kalman filter to estimate the location of the AUV. In order for the algorithm to work efficiently, the nearest neighbor standard filter is introduced as the algorithm of data association in the CML for associating the stored targets the sonar returns at each time step. The proposed CML algorithm is tested by simulations under various conditions. Experiments in a towing tank for one dimensional navigation are conducted and the results are presented. The results of the simulation and experiment show that the proposed CML algorithm is capable of estimating the position of the vehicle and the object and demonstrates that the algorithm will perform well in the real environment.

• Journal of Ship and Ocean Technology
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• 제12권3호
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• pp.1-13
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• 2008

In shipbuilding, diverse manufacturing techniques for automation have been developed and used in practice. Among them, however, the hull forming automation is the one that has not been of major concern compared with others such as welding and cutting. The basis of the development of this process is to find out how to extract thermal forming information. There exist various methods to obtain such information and the 3D design shape that needs to be formed should be extracted first for getting the necessary thermal forming information. Except well-established shipyards which operate 3D design systems, most of the shipyards only rely on 2.5D design systems and do not have an easy way to obtain 3D surface design data. So in this study, various shipbuilding design systems used by shipyards are investigated and a 3D design surface data extraction method is proposed from those design systems. Then an example is presented to show the extraction of real 3D surface data using the proposed method and computation of thermal forming information using the data.

• 한국전자통신학회논문지
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• 제14권3호
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• pp.601-606
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• 2019

렌티큘러 위치기반 시스템은 지상 및 실외중심의 지역, 건물, 선박, 지하 등 실내에 있는 사용자가 스스로 자신의 위치를 실시간으로 알릴 수 있는 위치정보 기술이다. 본 논문에서는 이전의 실내 위치 인식기술의 한계성과 문제점을 분석하고, 이용자 중심의 위치서비스 방법을 제안한다. 제안된 방법은 렌티큘러 스티커, 데이터베이스(DB) 수집 및 분석기술, 측위시스템으로 구성되어 있고, 측위오차기반 서비스를 실행하기 위한 기반 인프라로 활용될 수 있을 것이며, 실내 렌티큘러를 이용한 위치기반시스템 개발을 통하여 사용자 중심의 측위 정확도 향상뿐만 아니라, 각종 재난안전 상황에서 신속한 구조활동에 사용자 중심의 위치기반 시스템으로 활용할 수 있을 것이다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.734-745
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• 2021

In order to achieve a good and competitive FPSO design, the building cost and the motion performances are the two most critical and conflicting KPIs to be considered. In this study, the author's previous work (Lee, et al., 2021) on the optimization of an FPSO's hull dimensions with 1800 MBBLs storage capacity at Brazil field was extended using a multi-objective parametric optimization with the hull steel weight and the operability which are closely related to the building cost and the operational cost during the lifetime, respectively. For the purpose of more realistic and practical FPSO design, the constraints related to crew comfort and the safe helicopter take-off and landing operation were newly added. Also, the green water on deck was calculated accurately to check the suitability of the designed freeboard height using a newly developed real-time calculation module for the relative wave elevations. With aids of this updated optimization formulation, we presented multiple optimal FPSO dimensions expressed as a Pareto set which aids FPSO designers to conveniently select the practical and competitive dimensions. The excellence of the developed approach was verified by comparing the optimization results with those of FPSOs dimensioned for operation at West Africa and Brazil field.

• Membrane and Water Treatment
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• 제13권1호
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• pp.1-6
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• 2022

The regulations of the International Maritime Organization (IMO) have been steadily strengthened in ship emissions. Accordingly, there is a growing need for development of related technologies for the removal of contaminants that may occur during the treatment of SOx and NOx using a wet scrubber. However, this system also leads to wastewater production when the exhaust gas is scrubbed. In this research, we evaluated the performance of an ion selective resin process in accordance with scrubber wastewater discharge regulations, specifically nitrate discharge, by the IMO. Accelerated real and synthetic wastewater of wet scrubbers, contained high amounts of TDS with high nitrate, is used as feed water in lab scale systems. Furthermore, a pilot scale dissolved air flotation (DAF) using microbubble generator with ion exchange resin process was combined and developed in order to apply for the treatment of wet scrubber wastewater. The results of the present study revealed that operating conditions, such as resin property, bed volume (BV), and inlet wastewater flow rate, significantly affect the removal performance. Finally, through a pilot test, DAF with ion exchange resin process showed a noticeable improvement of the nitrate removal rate compared to the single DAF process.

• 한국군사과학기술학회지
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• 제26권3호
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• pp.281-301
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• 2023

The shipboard combat system is a key system for naval combat that supports a command and control process cycle consisting of Detect - Control - Engage in real time to ensure ship viability and conduct combat missions. Modern combat systems were developed on the basis of Open Architecture(OA) to maximize acceptance of latest technology and interoperability between systems, and actively introduced the COTS(Commercial-of-the-shelf). However, as a result of that, vulnerabilities inherent in COTS SW and HW also occurred in the combat system. The importance of combat system cybersecurity is being emphasized but cybersecurity research reflecting the characteristics of the combat system is still lacking in Korea. Therefore, in this paper, we systematically identify combat system threats by applying Data Flow Diagram, Microsoft STRIDE threat modelling methodology. The threats were analyzed using the Attack Tree & Misuse case. Finally we derived the applicable security requirements which can be used at stages of planning and designing combat system and verified security requirements through NIST 800-53 security control items.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2020년도 추계학술대회
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• pp.70-71
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• 2020

자율운항선박시대에는 인공지능기술이 VR, AR과 결합하여 더욱 진화된 몰입형 경험을 제공할 수 있을 것이다. 몰입 기술은 사용자의 오감을 현혹시켜 실제와 유사한 경험과 감성을 제공할 수 있다. VR이나 AR을 통해 자율운항 시 선원이 운항에 몰입할 수 있고 가상의 선박과 상호작용할 수 있는 자연스런 환경을 제공해 주는 것이 필요하다. 본 연구에서는 자율운항선박시대를 대비하여 선원들이 VR이나 AR을 통해 자율운항 시에 몰입형 사용자경험을 구현할 수 있는 핵심 특성이

• 수산해양기술연구
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• 제58권4호
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• pp.359-366
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• 2022

In this study, the load fluctuation of the main engine is considered to be a disturbance for the jacket coolant temperature control system of the low-speed two-stroke main diesel engine on the ships. A nonlinear PID temperature control system with satisfactory disturbance rejection performance was designed by rapidly transmitting the load change value to the controller for following the reference set value. The feed-forwarded load fluctuation is considered the set points of the dual loop control system to be changed. Real-coded genetic algorithms were used as an optimization tool to tune the gains for the nonlinear PID controller. ITAE was used as an evaluation function for optimization. For the evaluation function, the engine jacket coolant outlet temperature was considered. As a result of simulating the proposed cascade nonlinear PID control system, it was confirmed that the disturbance caused by the load fluctuation was eliminated with satisfactory performance and that the changed set value was followed.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2023년도 춘계학술대회
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• pp.261-262
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• 2023

자율운항선박의 도래와 예상 할 수 없는 선박의 구조 변화 및 적화 상태 변화로 인한 전복사고로부터 선박을 보호하기 위해서는 선박의 복원성 상태를 실시간으로 모니터링 것이 매우 중요합니다. 자율운항선박의 복원성 상태를 실시간으로 정밀 모니터링 시스템 개발은 운항자에게 사전에 위험을 경고하고 적화상태 보완 또는 평형수 상태 변형 등을 통하여 추가적은 복원성 확보를 위해서 필수적입니다. 본 연구는 실습선의 전자 경사계로 실시간 횡요 주기로 추정한 선박의 메타센터 높이(GM)의 정확도를 실험적으로 검증 하였습니다. 본 연구는 선박의 전자 경사계를 사용하여 선박의 복원성 안정성 상태를 실시간으로 평가하여 추정한 선박 GM의 정확도와 향후 연구에서 시스템 개선을 위한 요구 사항을 제시하였습니다.