• Journal of Ocean Engineering and Technology
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• v.38 no.1
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• pp.10-17
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• 2024

This study assessed the potential for crabbing motion in waterjet ships by exclusively employing stern thrusters. The theoretical considerations were validated through practical sea trials on the naval vessel PKG (Patrol Killer Guided missile) equipped with three stern thrusters. The control forces were calculated using the force equilibrium equation. The results showed that the hull exhibited rotations and lateral movements under wind influence. The port tail exhibited a leftward turning tendency due to the wind. This phenomenon arises from the dominance of the rotational force generated by the stern thruster over the lateral force exerted by the hull, making it challenging to maintain force equilibrium. In the sea trial, the hull rotated by 10° and moved 10.8 m laterally, with a longitudinal movement of 0.26 m. Remarkably, the lateral movement surpassed the longitudinal displacement, indicating the success of the trial. The substantial lateral travel distance provided tangible evidence that the crabbing motion of the ship is achievable using only stern thrusters. This study contributes valuable insights into enhancing the maneuverability of waterjet ships, offering practical applications for naval operations and maritime activities.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.3
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• pp.259-269
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• 2018

In this study, the second order bending moment induced by sea waves is calculated using the quadratic strip theory. The theory has the fluid forcing terms including the quadratic terms of the hydrodynamic forces and the Froude-Krylov forces. They are applied to a ship as the external forces in order to estimate the second order ship responses by fluid forces. The sensitivity of the second order bending moment is investigated by implementing the quadratic terms by varying the ship side angle for two example ships. As a result, it was found that the second order bending moment changes significantly by the variation of the ship side angle. It implies that increased flare angles at the bow and the stern of ships being enlarged would amplify their vertical bending moments considerably due to the quadratic terms and may make them vulnerable to the fatigue.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.4
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• pp.313-320
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• 2018

As ships operating on the Arctic route are exposed to various ice environments such as level ice, pre-swan, pack ice, ice ridge and brash ice, it is essential to estimate the ice resistance according to the ice environment. Methods for estimating the ice resistance include a method using mathematical model, numerical simulation, and a method using empirical formula. In this study, empirical formulas are used to estimate the ice resistance. The purpose of this study is to develop the ice resistance and attainable speed estimation program(I-RES) for brash ice. To develop the Brash ice attainable speed estimation algorithm, the environmental characteristics of the brash ice were analyzed, and the results of I-RES were evaluated by comparing the model test results of brash ice. The accuracy of I-RES for brash ice is around 20% in this study but it will be more developed near future with accumulating more model test results and calculation results.

• International Journal of Ocean System Engineering
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• v.2 no.4
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• pp.214-222
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• 2012

The shipbuilding process is changing due to changes in the development environment and technological requirements for military ships. This would also hold true for a submarine, because its shipbuilding process includes complicated design and construction conditions. System improvement efforts for the design and construction of military ships have continued with the goal of overcoming these conditions. At present, the Korea Navy is developing a 3,000 ton-class Korean type submarine, and its design is progressing by the introduction of a full 3D-ship CAD system. Although the 3D modeling system was introduced for effective design realization through the introduction of collaborative design and active utilization of M&S (modeling and simulation), the introduction effects are not yet generally obvious, according to the characteristics of ship design. The present paper discusses the collaborative environment for developing a submarine to enhance this. This paper proposes the architecture and data structure of a system for realizing collaborative design and discusses a case system developed on the basis of this.

• Journal of Ocean Engineering and Technology
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• v.27 no.1
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• pp.24-30
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• 2013

The Korea Navy has been making constant efforts to apply M&S (modeling and simulation) to naval ship development, and the generalization of M&S for ship development is a trend. M&S for ship design is used for the V&V (verification and validation) of its design and operation, including design verification and ergonomic design that considers the crew using the Naval Ship Product Model. In addition, many parts of this M&S are repeatedly accomplished regardless of the kinds of ships. This study aims to standardize M&S, which repeatedly applies similar verifications for operation scenarios. A congestion assessment simulation for the major spaces of ships was the subject of the standardization based on the leading research results of various researchers, and a simulation automation solution was suggested. An information model using XML was proposed through the simulation automation concept, and a prototype system based on it was implemented. The usability was shown through a case study that verified the operability performance of the crew messroom.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.1-10
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• 2017

The functions of various systems inside the naval ships have been improved and diversified to prepare for the future battlefield and satisfy new requirements. The number of missions and operating displays with which a crew has to deal has increased. In this paper, Integrated Service Framework for Naval Ships is proposed. The proposed framework is based on REST architecture and it interfaces the networks of each systems in the ship. The connected data and functions are rebuilt as an object and they are provided as HTTP and JSON based APIs. The prototype of the framework was implemented in a combat system test-bed and its feasibility was proved with performance tests. With the proposed framework, operational efficiency for a naval ship can be achieved by designing new integrated displays and HCI which utilize whole ship's capabilities.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.2
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• pp.639-647
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• 2019

A realistic numerical simulation technology using a Lagrangian Fluid-Structure Interaction (FSI) model was combined with a fracture algorithm to predict the fluid-ice-structure interaction. The failure of ice was modeled as the tensile fracture of elastic material by applying a novel FSI model based on the Moving Particle Semi-implicit (MPS) method. To verify the developed fracture algorithm, a series of numerical simulations for 3-point bending tests with an ice beam were performed and compared with the experiments carried out in an ice room. For application of the developed FSI model, a dropping water droplet hitting a cantilever ice beam was simulated with and without the fracture algorithm. The simulation showed that the effects of fracture which can occur in the process of a FSI simulation can be studied.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.4
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• pp.362-373
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• 2012

The ship recycling industry is growing rapidly. It is estimated that the International Maritime Organization's (IMO) decision to phase-out single hull tankers by 2015 will result in hundreds of ships requiring disposal. At present, the ship recycling industry is predominantly based in South Asia. Due to the bad practice of current scrapping procedure, the paper will highlight the harm occurring to health, safety and environment. The efforts of the Marine Environment Protection Committee (MEPC) which led to the signing of the Hong Kong International Convention are also reviewed. The criteria and standards required to reduce the risk and damage to the environment are discussed and a proposed plan for the safe scrapping of ships is then presented. A technological and economic study for the ship recycling in Egypt is carried out as a case study. This includes the ship recycling facility size and layout. The equipment and staff required to operate the facility are also evaluated. A cost analysis is then carried out. This includes site development, human resources, machineries and equipment. A fuzzy logic approach is used to assess the benefits of the ship breaking yard. The use of the fuzzy logic approach is found suitable to make decisions for the ship breaking industry. Based on given constraints, the proposed model has proved capable of assessing the profit and the internal rate of return.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.6 s.144
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• pp.673-678
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• 2005

IMO adopted ' International Convention for The Control and Management of Ships' Ballast Water and Sediments ' on February 13th 2004. According to this convention, a ballast water treatment system should be installed in all ships obligatorily up to a standard date. When the system is installed, economic propriety should be considered. The economic propriety analysis examines the profit of a relevant project which can be presented by a equation, (Profit) = (income) - (expense) - (tax). However, the ballast water system is not for the profit during the life cycle but for the satisfaction of the regulation. Therefore, the expense should be minimum against the profit. This study presents the LCC(Life-Cycle Cost) analysis for economic evaluation of several ballast water system of foreign products.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1106-1112
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• 2010

One of the considerations in weapon systems procurement is the objective of maximizing the current force. Also, offensive effects, rather than defense are valued in weapons system development and procurement. Especially, the survivability of a naval ship is equally important as the offensive effect of onboard weapons. In case of naval ships, development of attack tactics and research regarding damage minimization must be conducted through live fire exercise against actual targets in order to minimize damage from the enemy. However, it is difficult to conduct such adequate measures due to realistic limitations such as time and budget in order to verify and calculate a weapon system's attack and damage effects along with the lack of practical studies in this subject despite numerous interests. Research are being conducted utilizing M&S to estimate attack effects and study damages due to such reason, but the lack of authoritative data and development ability are limiting calculation of reliable results. Therefore, this study will propose a measure to increase survivability of a weapon system(ship/vessel) utilizing research of vulnerability from enemy attacks analysis method against a naval ship(Craft Air Cushion).