• 제목/요약/키워드: Maritime power

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해양강국 실천을 위한 행정조직 부활의 필요성 연구 (A Study on the Necessity of the Resurrection of Administration Organization for the Realization of Super Nation of Maritime and Fishery)

  • 김홍섭
    • 한국항만경제학회지
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    • 제27권4호
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    • pp.313-346
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    • 2011
  • 바다를 지배한 민족이 세계를 지배한다고 로마의 키케로(Cicero)가 말했다. 세계사에서 중요 역할을 한 국가는 대부분 바다의 중요성을 강조하였다. 페니키아, 그리스, 카르타고, 로마, 포르투칼, 스페인, 영국, 미국 등 세계는 바다를 지배해온 민족의 역사라 할 수 있다. 바다는 자원의 보고, 소통과 물류, 유통의 통로로 국가의 원활한 정치, 경제, 사회, 문화의 터전이며 바다는 동시에 꿈과 상상의 장이며, 가능성과 비전의 토대이다. 본 연구에서는 우리나라 해양강국의 실현이라는 비전의 실현을 위해 세계의 주요 국가와 역사를 개관하였다. 우리 주요 해양정책의 주요 이슈에 대한 실태와 전망을 살펴보았으며, 이를 토대로 우리 해양강국의 비전을 제시하였다. 2020년 세계 5대 해양강국, 세계 10위의 해양과학기술 보유 등을 비전으로 제시하고 세부추진 전략을 제안하였다. 이를 위해 해양수산부의 복원이 절실하며 그 이유와 필요성을 5가지 논리로 제시하였다. 또한 해양수산부의 복원의 향후 방향도 정책, 기능적 관점과 제도적 관점에서 제시하였다. 해양강국 대한민국은 해양수산부가 향후 정부조직 개편에서 반드시 복원되야 실현될 수 있다고 본다.

강대국 간의 경쟁시대와 미 해군의 증강 노력 (USN's Efforts to Rebuild its Combat Power in an Era of Great Power Competition)

  • 정호섭
    • Strategy21
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    • 통권44호
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    • pp.5-27
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    • 2018
  • The purpose of this paper is to look at USN's efforts to rebuild its combat power in the face of a reemergence of great powers competition, and to propose some recommendations for the ROKN. In addition to the plan to augment its fleet towards a 355-ships capacity, the USN is pursuing to improve exponentially combat lethality(quality) of its existing fleet by means of innovative science and technology. In other words, the USN is putting its utmost efforts to improve readiness of current forces, to modernize maintenance facilities such as naval shipyards, and simultaneously to invest in innovative weapons system R&D for the future. After all, the USN seems to pursue innovations in advanced military Science & Technology as the best way to ensure continued supremacy in the coming strategic competition between great powers. However, it is to be seen whether the USN can smoothly continue these efforts to rebuild combat strength vis-a-vis its new competition peers, namely China and Russian navy, due to the stringent fiscal constraints, originating, among others, from the 2011 Budget Control Act effective yet. Then, it seems to be China's unilateral and assertive behaviors to expand its maritime jurisdiction in the South China Sea that drives the USN's rebuild-up efforts of the future. Now, some changes began to be perceived in the basic framework of the hitherto regional maritime security, in the name of declining sea control of the USN as well as withering maritime order based on international law and norms. However, the ROK-US alliance system is the most excellent security mechanism upon which the ROK, as a trading power, depends for its survival and prosperity. In addition, as denuclearization of North Korea seems to take significant time and efforts to accomplish in the years to come, nuclear umbrella and extended deterrence by the US is still noting but indispensible for the security of the ROK. In this connection, the naval cooperation between ROKN and USN should be seen and strengthened as the most important deterrents to North Korean nuclear and missile threats, as well as to potential maritime provocation by neighboring countries. Based on these observations, this paper argues that the ROK Navy should try to expand its own deterrent capability by pursuing selective technological innovation in order to prevent this country's destiny from being dictated by other powers. In doing so, however, it may be too risky for the ROK to pursue the emerging, disruptive innovative technologies such as rail gun, hypersonic weapon... etc., due to enormous budget, time, and very thin chance of success. This paper recommends, therefore, to carefully select and extensively invest on the most cost-effective technological innovations, suitable in the operational environments of the ROK. In particular, this paper stresses the following six areas as most potential naval innovations for the ROK Navy: long range precision strike; air and missile defense at sea; ASW with various unmanned maritime system (UMS) such as USV, UUV based on advanced hydraulic acoustic sensor (Sonar) technology; network; digitalization for the use of AI and big data; and nuclear-powered attack submarines as a strategic deterrent.

IMT-2000 전방궤환 디지털 적응 선형전력증폭기 설계 (Design of IMT-2000 Feedforward Digital Adaptive Linear Power Amplifier)

  • 김갑기;박계각
    • 한국항해항만학회지
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    • 제26권3호
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    • pp.295-302
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    • 2002
  • 현재의 디지털 통신시스템은 매우 다양한 디지털 변조방식을 채택하고 있다. 이러한 통신시스템에서는 인접채널에 대한 간섭을 최대한 줄이기 위해서 필연적으로 선형 전력증폭기를 요한다. 선형 전력증폭기는 매우 다양한데 그 중에서 전방궤환 전력증폭기는 구조상 광대역이면서 선형화 정도가 매우 우수하다. 전방궤환 전력중폭기에 사용되는 지연선로의 손실로 인하여 전체효율이 감소한다. 본 논문에서는 이러한 지연선로를 손실이 매우 작은 지연필터를 사용함으로써 효율과 선형성을 동시에 개선하였다. 측정된 결과 ACLR이 약 17.43dB 개선되었으며 이것은 지연필터를 사용함으로써 2.54dB 더 개선되었음을 나타낸다.

Optimal Power Flow of DC-Grid Based on Improved PSO Algorithm

  • Liu, Xianzheng;Wang, Xingcheng;Wen, Jialiang
    • Journal of Electrical Engineering and Technology
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    • 제12권4호
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    • pp.1586-1592
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    • 2017
  • Voltage sourced converter (VSC) based direct-current (DC) grid has the ability to control power flow flexibly and securely, thus it has become one of the most valid approaches in aspect of large-scale renewable power generation, oceanic island power supply and new urban grid construction. To solve the optimal power flow (OPF) problem in DC grid, an adaptive particle swarm optimization (PSO) algorithm based on fuzzy control theory is proposed in this paper, and the optimal operation considering both power loss and voltage quality is realized. Firstly, the fuzzy membership curve is used to transform two objectives into one, the fitness value of latest step is introduced as input of fuzzy controller to adjust the controlling parameters of PSO dynamically. The proposed strategy was applied in solving the power flow issue in six terminals DC grid model, and corresponding results are presented to verify the effectiveness and feasibility of proposed algorithm.

Enhancement of the energy efficiency of hydrogen SOFC system by integrated cold energy utilization and waste heat recovery method

  • Nguyen Quoc Huy;Duong Phan Anh;Ryu Bo Rim;Lee Jin Uk;Kang Ho Keun
    • 한국항해항만학회:학술대회논문집
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    • 한국항해항만학회 2022년도 추계학술대회
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    • pp.160-161
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    • 2022
  • Hydrogen is bridge fuel with high energy content and environmentally friendly to satisfy the stringent IMO regulation relating to greenhouse gas (GHG) emissions. There is growing interest in hydrogen in numerous nations and regions illustrated by an extensive range of research and development in technology. Regarding maritime applications, researchers have recognized the utilization of hydrogen as a fuel for fuel cells, a device that converts the chemical energy of the fuel to electrical energy. Solid oxide fuel cell (SOFC), with high working temperature, is easy to combine with the waste heat recovery cycles/devices to increase output power and thermodynamic performances as well. Furthermore, the cold energy from liquid hydrogen supplied to SOFC can also be used to generate more power. In this study, we proposed a SOFC integrated system with the idea of combining the waste heat recovery from the SOFC exhaust stream and cold energy utilization from LH2. The designation is aimed to target small-scale vessel which uses electric propulsion for short distances voyage.

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중국군의 해양작전능력과 한국군의 과제 (PRC Maritime Operational Capability and the Task for the ROK Military)

  • 김민석
    • Strategy21
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    • 통권33호
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    • pp.65-112
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    • 2014
  • Recent trends show that the PRC has stepped aside its "army-centered approach" and placed greater emphasis on its Navy and Air Force for a wider range of operations, thereby reducing its ground force and harnessing its economic power and military technology into naval development. A quantitative growth of the PLA Navy itself is no surprise as this is not a recent phenomenon. Now is the time to pay closer attention to the level of PRC naval force's performance and the extent of its warfighting capacity in the maritime domain. It is also worth asking what China can do with its widening naval power foundation. In short, it is time to delve into several possible scenarios I which the PRC poses a real threat. With this in mind, in Section Two the paper seeks to observe the construction progress of PRC's naval power and its future prospects up to the year 2020, and categorize time frame according to its major force improvement trends. By analyzing qualitative improvements made over time, such as the scale of investment and the number of ships compared to increase in displacement (tonnage), this paper attempts to identify salient features in the construction of naval power. Chapter Three sets out performance evaluation on each type of PRC naval ships as well as capabilities of the Navy, Air Force, the Second Artillery (i.e., strategic missile forces) and satellites that could support maritime warfare. Finall, the concluding chapter estimates the PRC's maritime warfighting capability as anticipated in respective conflict scenarios, and considers its impact on the Korean Peninsula and proposes the directions ROK should steer in response. First of all, since the 1980s the PRC navy has undergone transitions as the focus of its military strategic outlook shifted from ground warfare to maritime warfare, and within 30 years of its effort to construct naval power while greatly reducing the size of its ground forces, the PRC has succeeded in building its naval power next to the U.S.'s in the world in terms of number, with acquisition of an aircraft carrier, Chinese-version of the Aegis, submarines and so on. The PRC also enjoys great potentials to qualitatively develop its forces such as indigenous aircraft carriers, next-generation strategic submarines, next-generation destroyers and so forth, which is possible because the PRC has accumulated its independent production capabilities in the process of its 30-year-long efforts. Secondly, one could argue that ROK still has its chances of coping with the PRC in naval power since, despite its continuous efforts, many estimate that the PRC naval force is roughly ten or more years behind that of superpowers such as the U.S., on areas including radar detection capability, EW capability, C4I and data-link systems, doctrines on force employment as well as tactics, and such gap cannot be easily overcome. The most probable scenarios involving the PRC in sea areas surrounding the Korean Peninsula are: first, upon the outbreak of war in the peninsula, the PRC may pursue military intervention through sea, thereby undermining efforts of the ROK-U.S. combined operations; second, ROK-PRC or PRC-Japan conflicts over maritime jurisdiction or ownership over the Senkaku/Diaoyu islands could inflict damage to ROK territorial sovereignty or economic gains. The PRC would likely attempt to resolve the conflict employing blitzkrieg tactics before U.S. forces arrive on the scene, while at the same time delaying and denying access of the incoming U.S. forces. If this proves unattainable, the PRC could take a course of action adopting "long-term attrition warfare," thus weakening its enemy's sustainability. All in all, thiss paper makes three proposals on how the ROK should respond. First, modern warfare as well as the emergent future warfare demonstrates that the center stage of battle is no longer the domestic territory, but rather further away into the sea and space. In this respect, the ROKN should take advantage of the distinct feature of battle space on the peninsula, which is surrounded by the seas, and obtain capabilities to intercept more than 50 percent of the enemy's ballistic missiles, including those of North Korea. In tandem with this capacity, employment of a large scale of UAV/F Carrier for Kill Chain operations should enhance effectiveness. This is because conditions are more favorable to defend from sea, on matters concerning accuracy rates against enemy targets, minimized threat of friendly damage, and cost effectiveness. Second, to maintain readiness for a North Korean crisis where timely deployment of US forces is not possible, the ROKN ought to obtain capabilities to hold the enemy attack at bay while deterring PRC naval intervention. It is also argued that ROKN should strengthen its power so as to protect national interests in the seas surrounding the peninsula without support from the USN, should ROK-PRC or ROK-Japan conflict arise concerning maritime jurisprudence. Third, the ROK should fortify infrastructures for independent construction of naval power and expand its R&D efforts, and for this purpose, the ROK should make the most of the advantages stemming from the ROK-U.S. alliance inducing active support from the United States. The rationale behind this argument is that while it is strategically effective to rely on alliance or jump on the bandwagon, the ultimate goal is always to acquire an independent response capability as much as possible.

Hydraulic Model Test of a Floating Wave Energy Converter with a Cross-flow Turbine

  • Kim, Sangyoon;Kim, Byungha;Wata, Joji;Lee, Young-Ho
    • International Journal of Fluid Machinery and Systems
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    • 제9권3호
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    • pp.222-228
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    • 2016
  • Almost 70% of the earth is covered by the ocean. Extracting the power available in the ocean using a wave energy converter has been seen to be eco-friendly and renewable. This study focuses on developing a method for analyzing a wave energy device that uses a cross-flow turbine. The motion of the ocean wave causes an internal bi-directional flow of water and the cross-flow turbine is able to rotate in one direction. This device is considered of double-hull structure, and because of this structure, sea water does not come into contact with theturbine. Due to this, the problem of befouling on the turbine is avoided. This study shows specific relationship for wave length and several motions.

Modified Wilkinson Power Divider for Multiple Harmonics Suppression

  • Kang In-Ho;Xu Hai-Yan
    • 한국항해항만학회지
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    • 제29권7호
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    • pp.615-618
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    • 2005
  • A new structure of the Wilkinson power divider that can suppress multiple harmonics output is presented The power divider consists of T-type or $\pi$-type capacitive loads and shunt resistors. Experimental results show that this power divider suppresses the second and the third harmonic components to less than -38dB, while maintaining the characteristics of a conventional Wilkinson power divider, featuring an equal power split, a simultaneous impedance matching at all ports and a good isolation between output ports.

Design and Analysis of a Power Control and Monitoring System for Buoy

  • Oh, Jin-Seok;Jo, Kwan-Jun
    • Journal of Advanced Marine Engineering and Technology
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    • 제33권7호
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    • pp.1068-1074
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    • 2009
  • This paper describes a study for the buoy which should be operated by a stand-alone power system. The field of this study is related to a power system operated by two batteries which depends on the load power. The fluctuation of the voltages makes the life cycle of the battery shorten. The control algorithm has been proposed for reducing the voltage pulsation of the battery by operation strategy according to using purpose such as main or sub power supply system. The power system with battery is separated two parts and this has been proved through a simulation and a sea experiment. In order for the experiment to use a wireless monitoring system has been installed in buoy. This paper shows an excellent test result of wireless monitoring system for buoy.

9개의 하모닉을 억제하는 월킨슨 전력 분배기 (Modified Wilkinson Power Divider for Harmonic 제거)

  • 강인호;김정훈
    • 한국전자파학회:학술대회논문집
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    • 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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    • pp.273-277
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    • 2003
  • This paper presents a structure of the Wilkinson power divider that can suppress the 9ea harmonic output. The power divider consists of ${\lambda}/4n$ open stubs, which are located at the $3{\lambda}/4$ branches and parallel connection of resistor which shunts the output ports. Experimental results show that this power divider suppresses from 1st to 9th harmonic components to less than -37dB, while maintaining the characteristics of a conventional Wilkinson power divider; featuring an equal power split, a simultaneous impedance matching at all ports and a good isolation between output ports. these results agree quite well with the simulation results.

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