• 해양안보
• /
• 제3권1호
• /
• pp.115-140
• /
• 2021

남중국해는 풍부한 해저 및 어로자원 뿐만 아니라 매년 4만여 척 이상의 선박이 통과하고, 세계 해양물류 50%, 원유 66%가 통과하는 중요한 해상교통로이다. 특히 대한민국의 수입 물동량의 30%, 에너지 수입량의 90%가 당 해역을 통과하고 있다. 미국과 중국은 이 해역의 중요성을 일찍이 깨달아 각각 '인도-태평양 전략', '일대일로(一帶一路) 전략'을 시행하는 등 국가전략적 차원에서 해양안보를 통한 국익을 구체화 하고 있다. 이런 지정학적 갈등은 남중국해에서 미국이 실시하는 '항행의 자유 작전'이라는 양상으로 드러나고 있다. 이러한 중요성에도 불구하고, 항행의 자유 작전에 대한 국내 연구는 미흡한 것이 사실이며, 기존 연구 대부분도 국제법과 국제 협약에 대한 분석을 중심으로 수행되었다. 본 논문은 항행의 자유 작전에 대한 전략적 인식을 통해 그 기원과 배경을 분석하고, 미·중 전략경쟁이 장기화되는 상황에서 한반도 안보에 주는 함의를 도출하고자 한다.

• Journal of Positioning, Navigation, and Timing
• /
• 제12권4호
• /
• pp.409-421
• /
• 2023

In order to develop navigation systems, simulators that provide navigation sensors data are required. A trajectory generator that simulates vehicle motion is needed to generate navigation sensors data in the simulator. In this paper, a trajectory generator for evaluating navigation system performance is proposed. The proposed trajectory generator consists of two parts. The first part obtains parameters from the motion scenario file whereas the second part generates position, velocity, and attitude from the parameters. In the proposed trajectory generator six degrees of freedom, halt, climb, turn, accel turn, spiral, combined, and waypoint motions are given as basic motions with parameters. These motions can be combined to generate complex trajectories of the vehicle. Maximum acceleration and jerk for linear motion and maximum angular acceleration and velocity for rotational motion are considered to generate trajectories. In order to show the usefulness of the proposed trajectory generator, trajectories were generated from motion scenario files and the results were observed. The results show that the proposed trajectory generator can accurately simulate complex vehicle motions that can be used to evaluate navigation system performance.

• Journal of Positioning, Navigation, and Timing
• /
• 제5권2호
• /
• pp.97-107
• /
• 2016

Military Autonomous Underwater Vehicle (AUV) is utilized to search a mine under the sea. This paper presents design and performance verification of real-time hybrid navigation system for AUV. The navigation system uses Doppler Velocity Log (DVL) integration method to correct INS error in underwater. When the AUV is floated on the water, the accumulated error of navigation algorithm is corrected using position/velocity of GPS. The navigation algorithm is verified using 6 Degree Of Freedom (DOF) simulation, Program In the Loop Simulation (PILS). Finally, the experiments are performed in real sea environment to prove the reliability of real-time hybrid navigation algorithm.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2000년도 추계학술대회논문집
• /
• pp.159-167
• /
• 2000

During the operation of crane system in the container yard, it is necessary to control the crane trolley position so that the swing of the hanging container is minimized. Recently an automatic control system with high speed and rapid transportation is required. Therefore, we designed a controller to control the crane system with disturbances and weight change. In this paper, we present the neural network two degree of freedom PID controller to control the swing motion and trolley position. Then we executed the computer simulation to verify the performance of the proposed controller and compared the performance of the neural network PID controller with our proposed controller in terms of the rope swing and the precision of position control. Computer simulation results show that the proposed controller has better performances than neural network PID with disturbances.

• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
• /
• pp.216-217
• /
• 2005

This paper presents an integrated navagation control concept for underwater vehicles under high speed navigation circumstance. First of all, in order to control an underwater vehicle with respect to automatic navigation, an integrated navigation control method is suggested in view of synchronous control for course keeping, diving and depth control. An exact nonlinear model equation with six-degree-of-freedom is derived for control algorithm. To identify various hydrodynamic coefficients of the equation, an experimental approach is introduced and results are demonstrated for MANTA type model.

• Strategy21
• /
• 통권42호
• /
• pp.154-195
• /
• 2017

This paper is to analyse conflict between the US and China over the South China Sea and Korea's responses. To this end the paper is composed of 6 chapters titled instruction; the current status of South China Sea sovereignty disputes; changes in US and Chinese maritime security strategies and the strategic values of the South China Sea; key issues and future prospects for US-China conflicts in the South China Sea; South Korea's security and diplomatic responses; and conclusion. The recent East Asian maritime security issue has evolved into a global issue of supremacy between the US and China, beyond conflicts over territorial disputes and demarcation among the countries in the region. China is pursuing offensive ocean policy to expand economic growth. The core of the maritime order that the United States intends to pursue is the freedom of navigation in the oceans and the maintenance of maritime access. China is making artificial islands in the South China Sea, claiming the sovereignty of these islands, building strategic bases in East Asia, and securing routes. The United States has developed several "Freedom of Navigation Operations" to neutralize the declaration of the territorial sea surrounding Chinese artificial islands. We can not be free from marine conflicts in the South China Sea and the East China Sea. Regarding the South China Sea dispute, it is expected that the strategic competition and conflict between the two countries will intensify due to China's failure to make concessions of core interests and adherence to the US compliance with international norms. In the midst of conflict over the South China Sea, we need a harmonious balance between our alliance security and economic diplomacy. We must continue our efforts to strengthen the ROK-US alliance but not to make China an enemy. Considering the significant impacts of the oceans on the survival and prosperity of the nation, we must continue to develop our interest in the oceans, appropriate investments and tactical strategies.

• Strategy21
• /
• 통권45호
• /
• pp.60-90
• /
• 2019

공해의 이용은 '항해의 자유'와 '기국주의'라는 관습법으로 형성되어온 원칙이 유엔해양법협약에서 명문화되어 공해 이용에 관한 두 개의 큰 축을 이루고 있다. 연안국의 해양에 대한 통제권이 확대되고 새로운 안보위협에 대처하기 위한 레짐이 생성되면서 공해의 자유에 관한 두 가지 기제를 축소하려는 유인과 시도가 있었다. '항해의 자유'와 '기국주의'는 인류가 바다에 진출한 이래 수 천 년에 걸쳐 형성된 관습법이고 오늘날 인류 공동의 유산인 바다를 평화롭고 질서 있게 이용하기 위한 법, 제도적 근간이 되고 있다. 따라서 공해상 타국 선박에 법 집행의 절차적 편리성과 집행국의 이익을 위해 이러한 원칙으로부터 예외를 만들거나 후퇴하기 시작하면 해양이용의 기본 틀 자체가 위협받을 수 있고 결국에는 해양질서는 강대국의 힘의 논리와 이익에 좌우 될 수 있다. 이러한 이유로 대북해상 제재와 같은 새로운 해양법 집행 레짐이나 조치는 무해통항제도, 공해이용의 자유와 같은 원칙을 존중하고 국제법의 틀 안에서 이루어져야 한다.

• 한국항해학회지
• /
• 제11권2호
• /
• pp.53-59
• /
• 1987

This paper describes the design theory of a weakly-coupled Tap-off with high density of coupling intervals for CATV and/or MATV systems, by which the degree of freedom in design and density of coupling intervals are significantly increased compared with the intrinsic one. It is also described how to construct the two-way divider (Tap-off) in the generalized type. Furthermore, the practical measurements of the frequency characteristics for a fabricated circuit show very good agreements with theoretical results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
• /
• pp.1907-1908
• /
• 2006

Recently, an automatic crane control system is required with high speed and rapid transportation. Therefore, when container is transferred from the initial coordinate to the finial coordinate, the container paths should be built in terms of the least time and without sway. Therefore, we calculated the anti-collision path for avoiding collision in its movement to the finial coordinate in this paper. And we constructed the neural network predictive two degree of freedom PID controller to control the precise navigation. The proposed predictive control system is composed of the neural network predictor, two degree of freedom PID controller, neural network self-tuner which yields parameters of two degree of freedom PID. We analyzed crane system through simulation, and proved excellency of control performance over the conventional controllers.

• International journal of advanced smart convergence
• /
• 제8권2호
• /
• pp.155-161
• /
• 2019

We introduces a mobile robot that can navigate on a power transmission line arranged in bundled conductors. The designs of the proposed robot are performed for navigation on bundled conductors, and the navigation method for bundled conductors and obstacle avoidance are presented. The robot consists of 13 degrees of freedom (DOF) with a symmetrical structure for the left and right parts, including the four wheel joints. The navigation method is designed using a combination of three motion primitives such as linear motion of counterbalancing box, linear motion of robot arm, and rotational motion of wheel part. To examine the performance of the proposed robot, navigation simulations are conducted using $ADAMS^{TM}$. The robot navigations were simulated on obstacle environments that consisted of two- and four-conductor bundles. Based on the simulation results, the performance of the proposed robot was reviewed through the analysis of the trajectories of end-effectors. We confirmed that the proposed robot was capable of achieving optimal navigation on bundled conductors that included obstacles.