• Journal of Ocean Engineering and Technology
• /
• v.23 no.2
• /
• pp.98-103
• /
• 2009

The resin infusion method is the latest technology of FRP laminating and cleaning to improve FRP hull quality. This method is focused on how to arrange infusion channels for the laminiating strategy. The laminating strategy using the resin infusion method has been utilized to complete the infusion work and remove the cavities on the FRP surface within the curing time. It is resulting from the arrangement of infusion and vacuum channels, the resin property, and the combination of FRP. This strategy has been depended on the field experience for manufacturing FRP without the resin infusion simulation. This study can help to improve the efficiency of FRP fabrication with the laminating strategy including the resin infusion simulation instead of the field experience.

• Strategy21
• /
• s.42
• /
• pp.318-346
• /
• 2017

Currently, security environmental instability is getting worse than ever in the East Asia including to Republic of Korea(ROK). Unlike several conventional issues such as maritime dispute -sometimes with islands- and competitions for getting natural resources, contemporary security dilemma issues followed by arms races among states deepens the power gap between strong and weak state within the region. It is notable that the arms races is the East Asia are mainly focused on naval power. As navy is the very possible force that influences neighboring states, submarine power is usually valued for its nature of stealth, mobile and aggression. Moreover, the submarine power is believed to be one of the highest valued weapon system since it shows actual effectiveness for influencing the other states while avoiding direct military conflicts compared to surface power. As a result, all states within the region are accelerating for getting such power these days. Japan, Most of all, is one of the leading state that aims to ensure self-survival and enlarge military influences under the US-Japan alliance by decisively supporting its power to the American containment strategy against China. In this regard, such movement surely sill influence on ROK both directly and indirectly as we sue the common field, the sea. Though, it has lots of restrictions for us to confront them with military forces as such confrontations within US-led alliances is not desirable upon considering current China and nK threats. As a result, ROK needs to limit the realm of alliance within the region while maintaining ROK-US alliance for getting national interests with both legal and justice superiority against Japan. This paper, as a result, is focused on suggesting the way to utilize submarines as a mean of naval power for both current security environments and the rising maritime threats in the East Asia. I concluded to participate ROK submarines in US-led military strategy against China by dispatching them into the East-China Sea and the North-East area of the Korean peninsula to protect both national interests and justice at the same tome. It should be one of the preemptive measure for confronting with neighboring states by utilizing strategic benefits of submarines while strengthening ROK-US alliances upon participating American Containment Strategy against China.

• Strategy21
• /
• s.44
• /
• pp.142-176
• /
• 2018

So far, the main threat to South Korea was North Korea. That is why South Korea established a strategy based on the threat of North Korea and most of the budget on defense was used to deter North Korea. Even though the neighboring countries(China, Japan, and Russia) are growing as a real threat with abilities and intentions based on their powerful naval forces, South Korea has not yet been able to establish a strategy that regards neighboring countries as a threat. But the decades-old structural mechanism of the Korean security environment is undergoing a radical change on April 27, 2018, through the South-North summit and the Panmunjom Declaration. Under the changing security environment, South Korea was placed in a complicated dilemma that had to deal with threats of two axes(China), three axes(China, Japan), and four axes(Japan, Russia). If the one axis threat(North Korea) is dominated by land threats, the second, third and fourth axis threats are threats from the sea. This paper analyzed the maritime strategy of Korea within the framework of maritime-geopolitics, in other words recognition and expansion of the sphere of maritime. I have designed that the maritime defense space that we can deny from threats is divided into three lines of defense: 1 line (radius 3,000km), 2 lines (2,000km), and 3 lines (1,000km). The three defense zones of the three lines were defined as an active defense(1 line), defensive offense(2 line), active offense(3 line). The three defense zones of the three lines were defined as the sphere of core maritime, As a power to deny the sphere of core maritime, it was analyzed as a maneuvering unit, a nuclear-powered submarine, the establishment of missile strategy, and the fortification of islands station. The marine strategy of South Korea with these concepts and means was defined as 'Offensive Maritime Denial Strategy'.

• Strategy21
• /
• s.33
• /
• pp.202-221
• /
• 2014

시진핑 시대를 맞이하여 중국은 국제사회에서 높아진 중국의 위상에 부응하는 지위와 권한을 인정받을 수 있는 외교정책으로서 최소한의 요구조건이 바로 핵심 이익(Core interests)을 지켜내는 것이며 이와 관련하여 국정목표로 '중국의 꿈'의 실현을 제시했다. 이에 따라 중국은 해양 분야에서 해양강국의 특징으로 다음 네 가지를 들고 있다. 첫째는 해양 경제 발전이며, 둘째는 해양 과학기술의 혁신, 셋째는 우아하고 아름다운 해양생태환경 조성, 넷째는 해양 방위능력을 중강하여 국가주권을 효과적으로 방위하고 해양의 평화발전을 수호하는 강력한 실력을 갖추는 것이다. 작금의 정세에서 보여지듯이 중국은 서해를 비롯하여 동·남중국해에서 매우 도전적인 해양활동을 보이고 있다. 이는 그동안 미국의 지역에 안정과 평화를 유지하기 위해 군사력을 주둔시켜 온 미국의 동아시아 해상정책에 대한 도전으로도 인식되기에 충분하다. 그렇다면 이에 대한 미국의 역할은 무엇인가. 필자는 다음 네 가지를 주장한다. 첫째, 더 좋은 상황 조성을 위해 역할 한다. 둘째, 모든 문제에 대해 방관자적인 입장에 선다. 셋째, 중국에 대해 보다 강경한 입장을 취한다. 넷째, 현상유지를 위해 노력한다.

• Strategy21
• /
• s.38
• /
• pp.83-111
• /
• 2015

In these days, 1949 revolt of admirals has a variety of evaluations. In 1949, many people thought that revolt of admirals is simply disobedience to Secretary of Defense. Revolt of admirals was considered that Navy was defeated to Air force. At that time, many people didn't put too much meaning this case. But at long last, the confidential documents about revolt of admirals opened to the public. This historic event's value was re-evaluated. Many researches were progressed in USA, On the other hand only some researches were progressed in Korea. So I try to study this topic and discover another meaning. Then, I will apply this lesson that obtained through study to our Korea Navy.

• Strategy21
• /
• s.36
• /
• pp.241-265
• /
• 2015

최근 몇 년 동안 나타난 러시아 해군의 부활(resurgence)은 우크라이나 사태로 본 러시아 군사력 증강을 대표하는 상징이다. 전통적으로 러시아 해양전략(Sea power)은 러시아 경제 및 안보 목표를 달성하는데 있어 핵심이었다. 러시아 해군은 주로 전략적 억제, 연안방어, 해상교통로 보호, 해외전개 그리고 군사력 투사 등의 임무를 수행한다. 특히 최근 들어 러시아 해군력이 양적 질적으로 증강되는 양상을 보이고 있으며, 이는 최근 잠수함, 수상함 그리고 해군항공 전력이 크게 증강되고 있는 현상에서 증명되고 있다. 이는 불과 몇 년 전까지 러시아 해군력에 대한 정비 및 작전 운용에 있어 많은 문제점을 보이던 부정적 사례와 현격히 다른 모습이다. 특히 푸틴 정부에 들어서 러시아 해군은 양적이며 질적인 증강뿐만이 아닌, 세계 해양에서의 원해 해군작전을 비록 지금은 간헐적이기는 하지만 활발히 실시하고 있으며, 러시아 주변국 해군과의 다양한 해군협력도 추진하고 있다. 궁극적으로 러시아 해군은 단기적으로 연안방어를 기본 임무로 수행할 것이나, 장기적으로는 과거 구소련 해군력 위상과 영향력을 부활시키기 위해 세계 무대에서의 군사적 영향력을 증진시키는 대양해군(Blue Water Navy)을 지향할 것이다.

• Journal of Ship and Ocean Technology
• /
• v.8 no.4
• /
• pp.45-55
• /
• 2004

How to achieve engineering collaboration among diverse engineering activities is one of the key topics in manufacturing fields nowadays. The infrastructure for collaborative engineering is essential, and it can be realized by information technologies and intelligent engineering applications in digital environments. Digital Manufacturing is a technology to facilitate effective product developments and agile productions by computer models representing the physical and logical schema and the behavior of real manufacturing systems including products, processes and factories. A digital factory as a well-designed and integrated digital environment is incorporated in it. In this paper, digital manufacturing is recommended as a good strategy for collaborative engineering, especially in product developments and productions. By business process analysis and some case studies, we suggested sophisticated digital models are very useful to concurrent and collaborative engineering. It is expected that digital manufacturing is a very good strategy for achieving dramatic time and cost savings in many engineering activities of many manufacturing industries, including machinery, automotive and shipbuilding.

• Strategy21
• /
• s.44
• /
• pp.54-78
• /
• 2018

The core of the current constitutional amendment pursued by the Abe administration depends on the status of the Japanese Self-Defense Forces, which include the right to engage in war, in the legal and regular military positions. This is an important turning point for the Abe administration, which aims to become a normal country for Japan, and it is a series of steps that followed in the revision of the U.S. and Japan guidelines in 2015 and the overhaul of the security law in 2016. In this paper, we propose building "A navy Attractive to Alliances" as a way to secure Korea's maritime security under the current security environment. The term "attraction" refers to the alliance "first priority" especially in the United States. The way to do this is to transform the paradigm of the ROK-U.S. alliance into a naval hub in the vast seas, which will allow us to strengthen our national defense and even deter threats from neighboring countries. To this end, our navy needs to have a more active approach to U.S. East Asian strategy. If we can convince the United States to be a nation that contributes more to its East Asian strategy, it will only lead to a strengthening of the status of its alliance and expansion of its unilateral support and military capability against Japan, thus minimizing Japan's influence.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.8
• /
• pp.2900-2922
• /
• 2021

In this paper, the power spectral density(PSD) for Multilevel Minimum Shift Keyed signal with modulation index h = 1/2 (M-ary MSK) are derived using the mathematical method of the Markov Chain model. At first, according to an essential requirement of the phase continuity characteristics of MSK signals, a complete model of the whole process of signal generation is built. Then, the derivations for autocorrelation functions are carried out precisely. After that, we verified the correctness and accuracy of the theoretical derivation by comparing the derived results with numerical simulations using MATLAB. We also divided the spectrum into four components according to the derivation. By analyzing these figures in the graphic, each component determines the characteristics of the spectrum. It is vital for enhanced spectral characteristics. To more visually represent the energy concentration of the main flap and the roll-down speed of the side flap, the specific out-of-band power of M-ary MSK is given. OMLCD(Optimum Maximum Likelihood Coherent Detection) of M-ary MSK is adopted to compare the signal received with prepared in advance in a code element T to go for the best. And M-ary MSK BER(Bit Error Rate) is compared with the same ary PSK (Phase Shift Keying) with M=2,4,6,8. The results show the detection method could improve performance by increasing the length of L(memory inherent) in the phase continuity.

• Journal of Ocean Engineering and Technology
• /
• v.33 no.2
• /
• pp.99-105
• /
• 2019

Unlike typical a dynamic positioning (DP) system, a DP-assisted mooring system must determine a set point (SP) that can ensure a mooring tension safety range to prevent an excessive increase in mooring tension. In this paper, a new algorithm for determining the SP is suggested in order to reduce the tension on all the mooring lines. To determine the SP, a working area around the vessel is represented by a rectangular grid. Thus, the size of the grid area is limited considering the offset of a vessel with a mooring system. At each grid's nodes, the resultant tension from all the mooring lines is estimated using the time history of the tension and vessel's position. The results of static analyses for each grid position are used to estimate the global tension. Consequently, the SP is automatically selected as a position satisfying criterion for minimizing the total tension. In order to validate the suggested algorithm, a motion simulation with the control system in the time domain and a discussion of the results are presented.