• Strategy21
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• s.32
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• pp.71-96
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• 2013

Not much research has focused on the combat history of the Manchu invasion of Korea. In particular, the role of the navy has not been properly examined. However, the naval forces of the Joseon Dynasty were critical to the military strategies adopted by the leaders of Joseon and the courts of the Ming and Later Jin dynasties. Therefore, by investigating the role of Joseon's navy, we can establish a better understanding of the dynamic situation in East Asia during this period. This paper traces the specific naval strategies of Joseon and also looks at the parts played by the Ming and Later Jin dynasties, based on their historical records. The main part of this paper consists of three chapters. Chapter 1 will uncover the reputation and the actual military strategies of Joseon's naval forces during this period. Chapter 2 will discuss the military strategies devised by the Ming and Later Jin courts as a reaction to each other and to Joseon's naval power. Last, Chapter 3 will examine how the naval forces of Joseon and Qing collided at Ganghwa Island in January 1637 and afterward Qing's requisition of Joseon's navy in its fight against the Ming. In conclusion, when Joseon's naval forces were strong enough to protect Joseon, they maintained the military status quo in East Asia. However, when their strength was superseded by that of the Later Jin's naval forces in a very short time, Joseon was forced to experience the worst humiliation in its history and East Asia to undergo a violent upheaval, the replacement of Ming by the Manchu/Qing dynasty.

• Strategy21
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• s.41
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• pp.108-152
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• 2017

This paper aims to analyze hegemonic competition and the role of naval power. To this end the paper is composed of four chapters titled introduction, the role of naval power in the hegemonic competition, the role of naval power in the East Asia, and the lessons and implications for the Korean Peninsula. Since the modern era, the hegemonic competition in the East Asian region has been the intrusion and struggle process between the world system and the East Asian regional system, and the ocean between these two systems has become the goal and means of supremacy(hegemony). Currently, the hegemonic competition between the US and China consists of systemic competition at the global level and marine competition at the regional level. When South Korea is forced to make strategic choices in the course of the US-China hegemonic competition, naval power will be the first factor to be considered. The ROK is asymmetrically maintaining a deep dependency relationship with the United States in terms of security and China in relation to the economy. And while the ROK's national economic power is acquired from the ocean, the ROK's military power is imbalanced because it is centered on the ground forces. These international relations and asymmetric-unbalanced resources distribution will not be able to effectively cope with the hegemonic competition between the US and China in the future, and will limit Korea's strategic choice. Since naval power and forces are the prerequisites for the hegemonic competition or the maintenance of supremacy we must construct balanced naval forces(naval power) that are not subordinate to the ground forces at the national strategic level for the future of the country.

• Strategy21
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• s.30
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• pp.99-142
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• 2012

Withe increased North Korea's security threats, the South Korean navy has been faced with deteriorating security environment. While North Korea has increased asymmetric forces in the maritime and underwater with the development of nuclear weapons, and China and Japan have made a large investment in the buildup of naval forces, the power of the Pacific fleet of the US, a key ally is expected to be weakened. The biggest threat comes from China's intervention in case of full-scale war with North Korea, but low-density conflict issues are also serious problems. North Korea has violated the Armistice Agreement 2,660 times since the end of Korean War, among which the number of marine provocations reaches 1,430 times, and the tension over the NLL issue has been intensifying. With tension mounting between Korea and Japan over the Dokdo issue and conflict escalating with China over Ieo do Islet, the US Navy has confronted situation where it cannot fully concentrate on the security of the Korean peninsula, which leads to need for strengthening of South Korea's naval forces. Let's look at naval forces of neighboring countries. North Korea is threatening South Korean navy with its increased asymmetric forces, including submarines. China has achieved the remarkable development of naval forces since the promotion of 3-step plan to strengthen naval power from 1989, and it now retains highly modernized naval forces. Japan makes an investment in the construction of stat of the art warship every year. Since Japan's warship boasts of its advanced performance, Japan's Maritime Self Defense Force is evaluated the second most powerful behind the US Navy on the assumption that submarine power is not included in the naval forces. In this situation, naval power construction of South Korean navy should be done in phases, focusing on the followings; First, military strength to repel the energy warship quickly without any damage in case of battle with North Korea needs to be secured. Second, it is necessary to develop abilities to discourage the use of nuclear weapons of North Korea and attack its nuclear facilities in case of emergency. Third, construction of military power to suppress armed provocations from China and Japan is required. Based on the above naval power construction methods, the direction of power construction is suggested as follows. The sea fleet needs to build up its war potential to defeat the naval forces of North Korea quickly and participate in anti-submarine operations in response to North Korea's provocations. The task fleet should be composed of 3 task flotilla and retain the power to support the sea fleet and suppress the occurrence of maritime disputes with neighboring countries. In addition, it is necessary to expand submarine power, a high value power asset in preparation for establishment of submarine headquarters in 2015, develop anti-submarine helicopter and load SLAM-ER missile onto P-3C patrol aircraft. In case of maine corps, division class military force should be able to conduct landing operations. It takes more than 10 years to construct a new warship. Accordingly, it is necessary to establish plans for naval power construction carefully in consideration of reality and future. For the naval forces to safeguard maritime sovereignty and contribute to national security, the acquisition of a huge budget and buildup of military power is required. In this regard, enhancement of naval power can be achieved only through national, political and military understanding and agreement. It is necessary to let the nation know that modern naval forces with improved weapon system can serve as comprehensive armed forces to secure the command of the sea, perform defense of territory and territorial sky and attack the enemy's strategic facilities and budget inputted in the naval forces is the essential source for early end of the war and minimization of damage to the people. If the naval power construction is not realized, we can be faced with a national disgrace of usurpation of national sovereignty of 100 years ago. Accordingly, the strengthening of naval forces must be realized.

• International Journal of Naval Architecture and Ocean Engineering
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• v.2 no.3
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• pp.146-154
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• 2010

In the present study, the wave excitation forces acting on an array of porous circular cylinders are examined based on diffraction problems. To calculate the wave forces, the fluid domain is divided into three regions i.e. a single exterior region, N interior regions and N beneath regions, and the diffraction in each fluid region is expressed by an eigenfunction expansion method with using 3-dimension liner potential theory (Williams and Li, 2000). Especially, the present method is extended to the case of an array of truncated porous circular cylinders to calculate the heave forces as well as surge and sway forces. To verify this method, the numerical results obtained by eigenfunction are compared with these results obtained by higher order boundary element method (Choi et al., 2000). The numerical results obtained by this study are in good agreement with those results. By changing the numbers of porous circular cylinders, the angle of incident wave and the porosity rate of circular cylinders, the wave excitation forces such as surge, sway and heave on an array of truncated porous circular cylinders are investigated.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.1
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• pp.60-68
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• 2018

A series of tests in an ice tank was carried out using a model-scale ship to investigate the ice loading process. The ship model Uikku was mounted on a rigid carriage and towed through a level ice field in the ice tank of the Marine Technology Group at Aalto University. The carriage speed and ice thickness were varied. In this paper, ice loading process was described and the corresponding ice forces on the horizontal plane were analysed. A new method is proposed to decompose different ice force components from the total ice forces measured in the model tests. This analysis method is beneficial to understanding contributions of each force component and modelling of ice loading on hulls. The analysed experimental results could be used for comparison with further numerical simulations.

• 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.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.1
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• pp.20-26
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• 2011

A weakly nonlinear seakeeping methodology for predicting motions and loads is presented in this paper. This methodology assumes linear radiation and diffraction forces, calculated in the frequency domain, and fully nonlinear Froude-Krylov and hydrostatic forces, evaluated in the time domain. The particular approach employed here allows to overcome numerical problems connected to the determination of the impulse response functions. The procedure is divided into three consecutive steps: evaluation of dynamic sinkage and trim in calm water that can significantly influence the final results, a linear seakeeping analysis in the frequency domain and a weakly nonlinear simulation. The first two steps are performed employing a three-dimensional Rankine panel method. Nonlinear Froude-Krylov and hydrostatic forces are computed in the time domain by pressure integration on the actual wetted surface at each time step. Although nonlinear forces are evaluated into the time domain, the equations of motion are solved in the frequency domain iteratively passing from the frequency to the time domain until convergence. The containership S175 is employed as a test case for evaluating the capability of this methodology to correctly predict the nonlinear behavior related to wave induced motions and loads in head seas; numerical results are compared with experimental data provided in literature.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.422-434
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• 2019

Several model-scale tests with a ship model have been performed in the ice tank of the Marine Technology Group in the Aalto University. The ship model of ice going tanker Uikku was mounted rigidly to the main carriage and towed through ice fields. The model tests were performed by changing ice thickness, drift angles and speeds in different ice fields. This paper reports the testing results and different phenomenon during model tests. The measured ice forces are presented and compared to level ice forces. The process of ice forces from broken ice on the ship is also analyzed for some typical tests. The research work could provide guidance on marine structures operating in waters covered by broken ice.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.5
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• pp.1-7
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• 2004

The Spar platform with deep draft is characterized as effective structure in extreme wave condition, which has larger natural period than that of waves in sea. In this paper, the time domain simulation of motion responses of Spar with catenary mooring line is presented in irregular waves. The memory effect is modeled by added mass at infinite frequency and convolution integrals in terms of wave damping coefficients. The added mass, wave damping coefficients and wave exciting forces are obtained from three-dimensional panel method in the frequency domain. The motion equations are consisted of forces for inertia, memory effect, hydrostatic restoring, wave exciting and mooring line. The forces of mooring line are modeled as quasi-static catenary cable.

• Strategy21
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• s.43
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• pp.5-28
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• 2018

The tensions between the U.S and China, which form the two pillars of the G2 era, seem to have persisted even after the Trump administration inaugurated. The strong confrontation between the two in recent foreign security issues may drive to develop an inadvertent military conflict, and it is high likely to occur in the maritime are. The purpose of this study is not only to analyze the balance of modernized naval forces in the PLAN through naval strategy changes and weapons system modernization trend, but also to predict the impact of the geographical proximity difference on the balance of naval forces in the disputed areas. It examined the impact of distance and geography on naval power by assessing the modernization pattern of the PLAN and capabilities in the context of two scenarios at different distances from China by 2020: one centered on Taiwan and the other on the Spratly Islands. The PLAN's strategy had impact on operational concept and forces construction. First, from the viewpoint of operation operational concept, it can be seen that the passive defense is changing into active defense. Second, in terms of power construction, it can threaten the surface and submarines of U.S power from a distance. And they generated follow three features; The ocean is not the focus of Chinese submarines, Horizontal and vertical expansion of Chinese naval vessels, The improvement of the suppression ability as the Chinese naval modernization ratio increases. The strength of the PLAN is dominant over the U.S in terms of reserves, and it can complement the qualitative deterioration by utilizing nearby bases in the vicinity of the mainland, such as the Taiwan Strait. However, due to the shortage of aircraft carriers, there is a possibility that it will take some time to secure the advantage of air and ocean in the amphibious operation. Therefore, as the dispute is prolonged, China may fail to achieve its original goal. In addition, the lack of cutting edge Commanding Ships may bring to weaken the C2 capabilities. At results, it is expected that PLAN will not be able to have a superiority in the short term due to lagging behind U.S advanced technology. Nevertheless, PLAN has strengthened its naval power through modernization sufficiently and it is highly likely to use force. Especially, it is more likely in the region where the naval power operation like the Taiwan Strait is possible with the almost equality to that of the United States. China will continue to use its naval forces to achieve a rapid and decisive victory over U.S in the close area from the land.