• Strategy21
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• 통권41호
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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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• 통권37호
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• pp.65-103
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• 2015

This study is an attempt to look into the future role of the ROKN and to provide a strategic way forward with a special focus on naval strategic concept and force planning. To accomplish this goal, this research takes four sequential steps for analysis: 1) assessing the role and utility of naval power of ROKN since its foundation back in 1945; 2) forecasting features of various maritime threats to influence the security of Korea in the future directly or indirectly; 3) identifying the roles to be undertaken by future ROKN; and 4) recommending Korean way of naval force planning and the operational concept of naval power. This study seeks to show that ROKN needs comprehensive role to better serve the nation with respect to national security, national prosperity and development, and future battle-space management. To safeguard the national security of Korea, it suggests three roles: 1) national guard for the peaceful unification; 2) protector of the maritime sovereignty; and 3) suppressor to maritime threats. Three more roles are highlighted for national prosperity: 1) escort of the national economy; 2) guardian for national maritime activities; and 3) contributor to the world peace. These roles need to be closely connected with the role for the battle-space management. This paper addresses the need for a dramatic shift of the central operational domain from land to maritime in the future. This will eventually offer future ROKN a leading role for developing strategic concept and force planning rather than merely a supporting one. This study finally suggests 'balanced' strategy both in concept development and force planning. A balanced force planning is a 'must' rather than an 'option' when considering a division of function between Task Fleets and Area Fleets, constructing cutting-edge conventional forces such as Aegis destroyer, CVs, or submarines, and the mix of high-profile platform and low-profile when composing future fleets. A 'balance' is also needed in operational concept. The fleet should be prepared to fulfill its missions based on two different types of force operation i.e., coercive or cooperative application of the utility of naval force. The findings and recommendations of the study are relevant today, and will be increasingly important in the future to achieve various political goals required by enhancing the utility of naval power.

• Strategy21
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• 통권32호
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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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• 통권34호
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• pp.149-177
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• 2014

Today distant oceans around the world are regarded as a major 'global commons' for international trade and transportation. Korea is not an exception, because Korea hugely depends on sea lines of communication (SLOC) for supplying vital commodities such as food and energy resource. As a result, assuring a free and safe use of distant ocean beyond territory is also an important agenda for Korea's maritime security. However there are a number of challenges for Korea to enjoy a free and safe use of distant ocean; dangers of regional maritime conflict in East Asia, naval arms race of China and Japan, and concerns on possible decline of U.S naval presence and power projection capabilities. These factors provide a reasonable basis for Republic of Korea Navy (ROKN) to pursue capabilities for major naval operations at distant ocean in a long-term perspective toward the year 2030. The introduction of aircraft carrier and nuclear-powered submarine is a key requirement for achieving this goal. ROKN needs to acquire a 'multi-role strategic landing platform' type of light aircraft carrier, which takes a role to escort naval task force by providing air superiority at distant ocean. Additionally nuclear-powered submarine will offer ROKN a formidable power to carry out offensive missions effectively at distant ocean.

• Strategy21
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• 통권46호
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• pp.123-157
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• 2020

이번 연구는 국제해사국의 연례 보고서를 바탕으로 2009~2014년 동안 아프리카 인근 해역에서 발생한 771건의 해적사건을 음이항 회귀분석(Negative binomial regression)을 이용하여 분석했다. 이번 연구를 통해 소말리아 인근에서 작전하는 다국적 해군함정의 숫자가 증가할수록 소말리아 인근에서 발생하는 해적사건이 감소하는 사실을 정량적으로 확인했다. 이를 통해 청해부대를 비롯하여 소말리아 인근에서 실시되고 있는 다국적 해군의 대(對)해적 작전이 실제로 해적사건 감소에 효과가 있음을 증명했다.

• 한국해양공학회지
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• 제24권4호
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• pp.8-12
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• 2010

The use of a tidal-current power system is one source of renewable energy that can minimize the environmental impact of power production and offer many other advantages compared to conventional energy sources. Unlike other energy production approaches, rate of energy production can be precisely predicted and the operational rate is very high. The performance of the rotor, which has a vital role in energy production using tidal currents, is determined by various design factors, and it should be optimized for the specific ocean environment in the field. The horizontal-axis turbine is very sensitive to the direction of flow, and flow direction changes due to rise and fall of the tides. To investigate the performance of the rotor considering the interaction problems with incidence angle of flow, a series of experiments were conducted, and a 3D CFD model was designed and analyzed by ANSYS CFX. The results and findings are summarized in the paper.

• 신재생에너지
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• 제16권1호
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• pp.31-40
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• 2020

Most countries in the world are trying to reduce the use of fossil fuels in the production of electricity and replace them with renewable energy technologies. In Korea, there are abundant ocean renewable energy sources that will play an important role in power generation in the future. This paper introduces a new tidal energy converter utilizing flow induced vibration (FIV), which can work efficiently, even in the currents slower than 1.0m/s. All tests were conducted at the Marine Renewable Energy Laboratory at the University of Michigan to examine the effects of the damping ratio of the electric generators on the power outputs and power efficiencies. In these tests, two identical circular cylinders were used, and passive turbulence controllers were applied to the surface of the cylinders to enhance the FIV. The experimental results showed that by using the two cylinders in the FIV, the power output and efficiency reached up to 31 W and 36%, respectively. In particular, the results showed that the power efficiency was higher at the relatively low flow speed (4

• Nuclear Engineering and Technology
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• 제53권1호
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• pp.69-78
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• 2021

Venturi meter is frequently used in feed water flow control system in a nuclear power plant. Its accurate measurement plays a vital role in the safe operation of the plant. This paper firstly investigates the influence of the length of each section of pipeline, the throat inner diameter of Venturi and the flow characteristics in a single-phase flow on the accuracy of Venturi measurement by numerical calculation. Then the flow and the accuracy are discussed in a multi-phase flow. Numerical results show that the geometrical parameters and the characteristics of complex turbulent flow in the single-phase flow have little impact on the accuracy of Venturi flow rate measurement. In the multi-phase flow, the calculated flow rate of Venturi deviated from the actual flow rate and this deviation value is closely related to the amount of steam in the pipeline and increases sharply with the increase of the amount of steam. The over-reading of Venturi flow rate is present.

• Strategy21
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• 통권46호
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• pp.5-28
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• 2020

2017년 트럼프 대통령의"자유롭고 열린 인도·태평양" 언급 후 이를 구체화하기 위해 2019년에 미 국방부는"인도·태평양 전략", 미 국무부는"자유롭고 열린 인도·태평양 : 공동 비전 추구"를 발표했다. 미국 외교/안보의 핵심인 국방부와 국무부에서 짧은 기간(약 6개월) 내 동일한 전략 (인도·태평양 전략) 을 구체화하기 위한 계획을 발표한 것은 이례적이다. 미 국방부와 국무부 보고서에서 미국은 자유롭고 열린 인도·태평양 구현을 위해 미국 자체의 노력 뿐만 아니라 동맹 및 파트너국의 협력과 책임분담, 동참을 강조하고 있다. 이에 따라 인도·태평양 주변 국가들은 자국의 이익에 따라 적극 참여 또는 유보적 입장을 취하고 있다. 이번 연구에서는 미국의 인도·태평양 전략 동참 요구에 대한 한국의 입장을 결정함에 있어 참고사항이 될 수 있는 주변국의 입장과 인도·태평양 전략 참여시 장·단점은 무엇인지 살펴보고자 한다. 또한"인도·태평양"이라는 단어에서도 알 수 있듯이 인도·태평양 전략을 뒷받침하는 주요 수단은 해군력이 될 것이므로, 인도·태평양 전략에서 한국해군의 역할을 무엇인지 살펴보고자 한다.

• East Asian mathematical journal
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• 제32권1호
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• pp.35-41
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• 2016

We introduce formal symbols of product type and of minimum type and show that the formal power series representation for $e^p$ is a formal symbol of product type, where p is a formal symbol of minimum type.