• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.97-100
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• 2013

전 세계 국제무역거래의 80%가 해상운송으로 이루어지고 있음에 따라, 연 6%로 세계 컨테이너 물동량의 증가가 전망됨에 따라 선박기인 온실가스의 증가에 대한 관심과 규제가 강화되고 있다. 즉 IMO 제62차 해양환경보호위원회에서 선박기인 온실가스 규제방안으로 EEDI와 SEEMP를 도입, 현재 발효 중에 있으며, 각 국의 항만당국 또한 대기오염 등의 환경규제 정책의 일환으로 그린 또는 에코포트 정책을 수립하여 이행 중에 있다. 이러한 해운환경의 변화로 인하여 해운선사는 글로벌 경쟁력 강화와 환경규제에 대응하기 위하여, 선박의 대형화를 통한 규모의 경제 실현은 물론, 급등하는 유가와 환경규제에 대비하여 고 에너지효율 및 저탄소 선박에 대한 수요가 늘어나고 있다. 이에 일본, 싱가폴, 노르웨이 등 EU 국가 등의 해운 선진국들은 1990년대 후반부터 친환경 선박의 개발에 대한 국가적 프로젝트를 체계적으로 이행해 오고 있으며, 이를 통한 친환경 선박기술의 확보와 친환경 선박시장의 점유율을 높이고 있는 추세이다. 따라서 본 논문은 선진 해운국가들이 수행중인 친환경 선박개발의 현황에 대한 벤치마킹을 통하여 상대적으로 뒤쳐져 있는 우리나라 친환경 선박개발 방안을 위한 여러 정책적 제안을 하고자 한다.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.6
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• pp.457-465
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• 2018

Since IMO has discussed the effectuation of the EEDI, EEOI and SEEMP, each country, shipping company, shipbuilding company and research institute have been requested to prepare the design, construction and operation of the efficient ship. From the shipbuilding company's point of view, it was necessary to develop a method based on the maneuvering equations of motion in a bid to estimate the EEOI considering the design, model test results and the calculation results of the ship. In this paper, the estimation method of RPM, power and fuel consumption proposed in the previous research was developed to construct a framework that helps in the estimation of the EEOI. It was possible to estimate the EEOI from the estimated ship speed (distance), LNG cargo mass, fuel consumptions and emission factors according to the type of fuel. The rapid increase of the evaluated EEOI was observed when the LNGC with ME-GI engine executing the course changed with a large difference. This prompted the comparison of the type of fuel on the estimated EEOI by considering HFO, LNG fuel and MGO properties.

• Journal of Ocean Engineering and Technology
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• v.35 no.1
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• pp.13-23
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• 2021

Since the introduction of the mandatory energy efficiency design index (EEDI), several studies have been conducted on the maneuverability of waves owing to the decrease in engine power. However, most studies have used the mean wave force during a single cycle to evaluate maneuverability and investigated the turning performance. In this study, we calculated the external force in accordance with the angle of incidence of the wave width and wavelengths encountered by KVLCC2 (KRISO very large crude-oil carrier) operating at low speeds in regular waves using computational fluid dynamics (CFD). We compare the model test results with those published in other papers. Based on the external force calculated using CFD, an external force that varies according to the phase of the wave that meets the hull was derived, and based on the derived external force and MMG control simulation, a maneuvering simulation model was constructed. Using this method, a weather vaning simulation was performed in regular waves to evaluate the course-keeping ability of KVLCC2 in waves. The results confirmed that there was a difference in the operating trajectory according to the wavelength and phase of the waves encountered.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.674-690
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• 2021

This study proposes a hybrid marine power system combining dual-fuel generators, a fuel cell, and Vanadium Redox Flow Batteries (VRFB). Rigorous verification and validation of the dynamic modelling and integration of the system are conducted. A case study for the application of the hybrid propulsion system to a passenger ship is conducted to examine its time-variant behaviour. A comprehensive model of the reversible and irreversible capacity degradation of the VRFB stack unit is proposed and validated. The capacity retention of the VRFB stack is simulated by being integrated within the hybrid propulsion system. Reversible degradation of the VRFB stack is precisely predicted and rehabilitated based on the predefined operational schedule, while the irreversible portion is retained until the affected components are replaced. Consequently, the advantages of the VRFB system as an on-board ESS are demonstrated through the application of a hybrid propulsion system for liner shipping with fixed routes.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.372-384
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• 2022

Total shipping accounts for 2.9 % of the annual average percentage of global anthropogenic GHG emissions. The International Maritime Organization implements EEDI (Energy Efficiency Design Index), Energy Efficiency eXisting-ship Index (EEXI), and Carbon Intensity Indicator (CII) as regulatory frameworks for shipping decarbonization. The Republic of Korea has enforced the Act on Development and Popularization of Greenship from 2020 and publicly announced the 1st national plan which was named 『2030 Greenship-K Promotion Strategy』 for the activation of a greenship market. The Greenship Certification Scheme is going on for the sustainability of Korean shipbuilding and shipping industries, to secure clean maritime environments, as well as to contribute to the national economy. Greenship Certification guarantees the credit of such eco-friendly technologies and products for shipping. The certification is going to be the basis of industrial competitiveness in coastal and international shipping. This study investigates an existing certification process, identifies the limitations, and proposes the process improved with several case studies. The improved certification scheme may have rationality for Net-zero with regard to climate alignment.

• Journal of Ocean Engineering and Technology
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• v.36 no.3
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• pp.168-180
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• 2022

The IMO has decided to proceed with the early introduction of EEDI Phase 3, a CO₂ emission regulation to prevent global warming. Measures to reduce CO₂ emissions for ships that can be applied immediately are required to achieve CO₂ reduction. We set six different CO₂ emission scenarios according to the type of ship and fuel, and designed a monoethanolamine-based CO₂ capture process for ships using a rate-based model of Aspen Plus v10. The simulation model using Aspen Plus was validated using pilot plant operation data. A ship inevitably tilts during operation, and the performance of a tilted column decreases as its height increases. When configuring the conventional CO₂ capture process, we considered that the required column heights were so high that performance degradation was unavoidable when the process was implemented on a ship. We applied a parallel column concept to lower the column height and to enable easy installation and operation on a ship. Simulations of the parallel column confirmed that the required column height was lowered to less than 3 TEU (7.8 m).

• Journal of the Society of Naval Architects of Korea
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• v.54 no.3
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• pp.171-186
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• 2017

This paper introduces a study on ship performance in waves to consider the effects of added resistance in the early stage of hull-form design. A ship experiences a loss of speed in actual seaways, hence this study proposes the overall procedure of a new design concept that takes into account the hydrodynamic performance of ship in waves. In the procedure, the added resistance is predicted using numerical methods: slender-body theory and Maruo's far-field formulation, since these methods are efficient in initial design stage, and an empirical formula is adopted for short waves. As computational models, KVLCC2 hull and Supramax bulk carrier are considered, and the results of added resistance and weather factor for test models are discussed. The computational results of vertical motion response and added resistance of KVLCC2 hull are compared with the experimental data. In addition, the sensitivity analysis of added resistance and weather factor for KVLCC2 hull to the variations of ship dimensions are conducted, and the change of the added resistance and propulsion factors after hull form variations are discussed.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.6
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• pp.459-479
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• 2014

This paper considers experimental and numerical studies on added resistance in waves. As the numerical methods, three different methods, strip method, Rankine panel method and Cartesian-grid method, are applied. The computational results of vertical motion response and added resistance are compared with the experimental data of Series 60($C_B=0.8$) hull, S175 containership and KVLCC2 hull. To investigate the influence of above-still water hull form, a Rankine panel method is extended to two nonlinear methods: weakly-nonlinear and weak-scatterer approaches. As nonlinear computational models, three ships are considered: original KVLCC2 hull, 'Ax-bow' and 'Leadge-bow' hulls. Two of the three models are modified hull forms of original KVLCC2 hull, aiming the reduction of added resistance. The nonlinear computational results are compared with linear results, and the improvement of computational result is discussed. As experimental approach, a series of towing-tank experiment for ship motions and added resistance on the three models (original KVLCC2 hull, 'Ax-bow' and 'Leadge-bow') are carried out. For the original KVLCC2 hull, uncertainty analysis in the measurement of vertical motion response and added resistance is performed in three waves conditions: ${\lambda}/L=0.5$, 1.1, 2.0. From the experimental results, the effects of hull form on added resistance are discussed.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.1
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• pp.18-25
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• 2017

This study deals with numerically comparing performance according to rudder shape called 'Twisted rudder and Wavy twisted rudder'. In comparison with conventional rudder, rudder with wavy shape has showed a better performance at high angles of attack($30^{\circ}{\sim}40^{\circ}$) due to delaying stall. But most of study concerned with wavy shape had been performed in uniform flow condition. In order to identify the characteristics behind a rotating propeller, the present study numerically carries out an analysis of resistance and self-propulsion for KCS with twisted rudder and wavy twisted rudder. The turbulence closure model, Realizable $k-{\epsilon}$, is employed to simulate three-dimensional unsteady incompressible viscous turbulent and separation flow around the rudder. The simulation of self-propulsion analysis is performed in two step, because of finding optimization case of wavy shape. The first step presents there are little difference between twisted rudder and case of H_0.65 wavy twisted rudder in delivered power. So two kind of rudders are employed from first step to compare lift-to-drag ratio and torque at high angles of attack. Consequently, the wavy twisted rudder is presented as a possible way of delaying stall, allowing a rudder to have a better performance containing superior lift-to-drag ratio and torque than twisted rudder at high angles of attack. Also, as we indicate the flow visualization, check the quantity of separation flow around the rudder.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.6
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• pp.471-477
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• 2015

When a ship sails in a seaway, the resistance on a ship increases due to incident waves and winds. The magnitude of added resistance amounts to about 15–30% of a calm-water resistance. An accurate prediction of added resistance in waves, therefore, is essential to evaluate the performance of a ship in a real sea state and to design an optimum hull form from the viewpoint of the International Maritime Organization (IMO) regulations such as Energy Efficiency Design Index (EEDI) and Energy Efficiency Operational Indicator (EEOI). The present study considers added resistance problem of AFRAMAX-class tankers with the conventional bow and Ax-bow shapes. Added resistance due to waves is successfully calculated using 1) a three-dimensional time-domain seakeeping computations based on a Rankine panel method (three-dimensional panel) and 2) a commercial CFD program (STAR-CCM+). In the hydrodynamic computations of a three-dimensional panel method, geometric nonlinearity is accounted for in Froude-Krylov and restoring forces using simple wave corrections over exact wet hull surface of the tankers. Furthermore, a CFD program is applied by performing fully nonlinear computation without using an analytical formula for added resistance or empirical values for the viscous effect. Numerical computations are validated through four degree-of-freedom model-scale seakeeping experiments in regular head waves at the deep towing tank of Hyundai Heavy Industries.