• Journal of the Society of Naval Architects of Korea
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• v.56 no.6
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• pp.497-506
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• 2019

Literature survey was conducted on the 2013 Interim Guidelines for determining the minimum propulsion power to maintain the manoeuvrability of ships in adverse conditions. The International Maritime Organization (IMO) Marine Environment Protection Committee (MEPC) documents related with the Guidelines were reviewed. Compatibility of the present Guidelines can be checked by two different levels: (Level 1) minimum power lines assessment and (Level 2) simplified assessment. The IHS (Information Handling Services) sea-web data on the bulk carriers and the tankers, which were built after 2000, were used to examine the Level 1 assessment. KVLCC2 was used to examine the Level 2 assessment. Regarding the Level 2 assessment, effects of the adverse weather conditions, the added resistance due to waves, the wake fractions and the thrust deduction factors were discussed.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.415-420
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• 2018

The Energy Efficiency Design Index (EEDI) introduced by the Marine Environment P rotection Committee(MEPC) in International Maritime Organization(IMO) has significantly assisted in regulating CO2 emissions. However, in adverse weather conditions, it can lead to accidents due to slow steaming of vessels and low engine propulsion power. In response to this issue, the MEPC presented guidelines for the minimum propulsion power of the main engine for maintaining the course of vessels in adverse weather conditions. However, the guidelines are only applicable for vessels with a deadweight of 20,000 tons, leaving out small and medium ships. This study evaluated vessels subject to the guidelines of minimum propulsion power and proposed revised guidelines. In addition, relevant cases of marine accidents were investigated with the aim of investigating the minimum propulsion power of main engine for medium and small ships not covered by the guidelines. In order to achieve this, engine propulsion power was analyzed according to the size of the affected vessels. The results obtained from this study could be used as a minimum power criterion that can be considered for ship building to reduce marine accidents in adverse weather for small and medium ships.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.1
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• pp.40-48
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• 2019

Hybrid electric propulsion systems (H-EPSs) are an intermediate step for integrated full electric propulsion warships. H-EPSs are a dynamic combination of mechanical and electrical propulsion systems to achieve the required mission performances. The system modes could adapt to meet the requirement of the various operation conditions of a warship. This paper presents a configuration and operating modes of H-EPSs considering the operation conditions of a destroyer class warship. The system has three propulsion modes, namely, motoring mode, generating mode [power take off (PTO) mode], and mechanical mode. The PTO mode requires a careful fuel efficiency analysis because the fuel consumption rate of propulsion engines may be low compared with the generator's engines depending on the loading power. Therefore, the calculation of fuel consumption according to the operating modes is performed in this study. Although the economics of the PTO mode depends on system cases, it has an advantage in that it ensures the reliability of electric power in case of blackout or minimum generator operation.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.2
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• pp.169-176
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• 2022

Laser ablation propulsion(LAP) is the method to create impulse by laser ablation. It can be used to deorbit the space debris(SD), as its long-range property and versatility on any material. In this paper, we find out several requirements of the LAP system(LAPS) to deorbit the SD by simple numerical calculations of the SD orbit and laser beam flux. As a result, minimum operable altitude angle turned out to be a crucial variable to the LAPS. Moreover, if minimum operable altitude angle is 10°, and if the minimum distance between the LAPS and the SD is below 450 km, 1 m/s² is sufficient to deorbit the SD by once. With 18 kJ/3 ns pulsed laser and cube shaped 100 kg SD, 1 m/s² acceleration can be achieved by increasing the pulse repetition rate over 34~53 Hz, depending on the size of the SD. This capability could compare with the conceptual design of the Japan Establishment for a Power-laser Community Harvest(J-EPoCH) facility, which include 8 kJ, 5 PW@100 Hz laser.

• Advances in aircraft and spacecraft science
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• v.4 no.6
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• pp.651-677
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• 2017

For the past ten years' efforts have been made to introduce environmentally-friendly "green" electric-taxi and maneuvering airplane systems. The stated purpose of e-taxi systems is to reduce the taxiing fuel expenses, expedite pushback procedures, reduce gate congestion, reduce ground crew involvement, and reduce noise and air pollution levels at large airports. Airplane-based autonomous traction electric motors receive power from airplane's APU(s) possibly supplemented by onboard batteries. Using additional battery energy storages ads significant inert weight. Systems utilizing nose-gear traction alone are often traction-limited posing serious dispatch problems that could disrupt airport operations. Existing APU capacities are insufficient to deliver power for tractive taxiing while also providing for power off-takes. In order to perform comparative and objective analysis of taxi tractive requirements a "standard" taxiing cycle has been proposed. An analysis of reasonably expected tractive resistances has to account for steepest taxiway and runway slopes, taxiing into strong headwind, minimum required coasting speeds, and minimum acceptable acceleration requirements due to runway incursions issues. A mathematical model of tractive resistances was developed and was tested using six different production airplanes all at the maximum taxi/ramp weights. The model estimates the tractive force, energy, average and peak power requirements. It has been estimated that required maximum net tractive force should be 10% to 15% of the taxi weight for safe and expeditious airport movements. Hence, airplanes can be dispatched to move independently if the operational tractive taxi coefficient is 0.1 or higher.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.194-197
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• 2017

Aircraft engine and auxiliary power units are certified in processes of design, production according to airworthiness requirements. The aircraft engines shall demonstrate compliance with the design and production through the Type Certificate and the auxiliary power unit shall demonstrate compliance with the design and production through the Technical Standards Order Approval. MOLIT(Ministry of Land, Infrastructure and Transport) established the law and the airworthiness requirements for aircraft engines such as KAS Part 33 but didn't issue the Technical Standards Order for auxiliary power unit. In this paper, we proposed and explained the plan for improvement of our aircraft engines industry through building and expanding the certification infra-structure for aircraft engines and auxiliary power unit.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.666-671
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• 2023

As international environmental regulations on ship emissions are gradually strengthened, interest in electric propulsion and hybrid propulsion ships is increasing, and various solutions are being developed and applied to these ships, especially stabilization of the power system and system efficiency. The direct current distribution system is being applied as a way to increase the power. In addition, verification and testing of safety and performance of marine DC distribution systems is required. As a result of establishing a DC distribution test bed, verifying the performance of the DC distribution (variable speed power generation) system, and analyzing fuel consumption, this study applied a variable speed power generation system that is applied to DC power distribution for ships, and converted the power output from the generator into a rectifier. A system was developed to convert direct current power to connect to the system and monitor and control these devices. Through tests using this DC distribution system, the maximum voltage was 751.5V and the minimum voltage was 731.4V, and the voltage fluctuation rate was 2.7%, confirming that the voltage is stably supplied within 3%, and a variable speed power generation system was installed according to load fluctuations. When applied, it was confirmed through testing that fuel consumption could be reduced by more than 20% depending on the section compared to the existing constant speed power generation system.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.6
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• pp.120-125
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• 2004

There are very few numbers of 115K FPP (Fixed Pitch Propulsion) Tankers for the Baltic ice class IA because the minimum power requirement of FMA (Finish- Swedish Maritime Association) needs quite large engine power and the 40 m Beam is out of calculation range of FMA minimum power requirements. The shipyard has no choice except to increase the engine power to satisfy FMA minimum power requirement Rule. And the operation cost, efficiency of hullform and its building cost are not good from the ship owners' point of view To solve this problem, the experience of ice breaking tanker development and the ice tank test results were adopted. The main idea to reduce the ice resistance is by reducing waterline angle at design load waterline. The reason behind the main idea is to reduce the ice-clearing force. Two hull forms were developed to satisfy Baltic Ice class IA. Two ice tank tests and one towing tank test was performed at MARC (Kvaener-Masa Arctic Research Center) and SSMB (Samsung Ship Model Basin) facilities, respectively. The purpose of these tests was to verify the performance in ice and open water respectively The hull form 2 shows less speed loss compared to Hull form 1 in open water operation but hull form 2 shows very good ice clearing ability. finally the Hull Form 2 satisfying Baltic ice class IA. The merit of this hull form is to use the same engine capacity and no major design changes in hull form and other related designs But the hull structure has to be changed according to the ice class grade. The difference in two hull form development methods, ice model test methods and analysis methods of ice model test will be described in this paper.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.128-133
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• 2005

In this study, performance design programs for components of a turbopump unit (TPU) in a Liquid Rocket Engine (LRE), that has non-cryogenic centrifugal pumps and 1-stage impulse turbine with partial admission nozzle, were developed. The programs were integrated in a TPU module by balancing the mass flow rate for pump-turbine power, and the module was inserted into the LRE system conceptual design program. The fundamental design conditions, satisfying LRE system requirements and minimum mass flow rate condition of gasgenerator, were found and compared with data from a Russian liquid rocket engine.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.207-214
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• 2023

Ships emit significant amounts of air pollution. To reduce ship emissions, the government has implemented the Eco-Friendly Ship Act to improve the marine air environment, under which the use of eco-friendly ships that use eco-friendly energy as a power source encouraged and technologies to reduce marine pollution are developed. Therefore, the revision of relevant laws and systems such as inspection and facility standards for the safe operation of eco-friendly ships is urgently needed, especially those for fishing vessels, which account for the majority of domestic coastal vessels. This study defines the core equipment for the application of electric complex propulsion systems to fishing boats and presents a minimum safety standard plan for the adoption and dissemination of eco-friendly fishing boats.