• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1028-1034
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• 2011

This paper have been studied that ocean wave power vibration generation system with two D.O.F.(degree of freedom) consists of buoy and vibration generation system with two D.O.F. for using efficiency of ocean wave energy. It selected main frequencies ${\omega}_1$, ${\omega}_2$ in frequency with ocean wave and it fitted them to the natural frequencies of vibration system with two D.O.F. in the vibrational power generation system. Then each the relative velocity of between the winding coil and the permanent magnet is faster than the velocity of ocean wave up and down motion by resonance phenomenon. Also the ocean wave power generation with two D.O.F. obtained the more electric energy then the ocean wave power generation with one D.O.F. by coupling effect for two D.O.F. vibration system. Therefore ocean wave power vibration generation system with two degree of freedom that is proposed in this paper has merits which not only using more energy in the ocean wave but also obtaining more electronic energy.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.5
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• pp.341-346
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• 2017

Knowing the mean free paths (MFPs) of thermal phonons is an essential step in performing heat transfer analysis for nanomaterials, and in determining the optimum design for tailoring the heat transfer characteristics of nanomaterials. In this study, we present a method that can be used to calculate accurately the phonon MFP spectra of nanostructures based on simple phonon kinetic theory. Here, the kinetic theory may be employed by extracting only the diffusive-transport part of the phonon spectrum (i.e., the MFPs are less than a thermal length). By considering phonon dispersion and polarization effects, the phonon MFP distributions of silicon at room temperature are calculated from phonon transport properties and the spectral MFP. Our results are validated by comparison with those of the first principle and MFP spectroscopy data.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.1
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• pp.16-22
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• 2016

The research on two-wheeled inverted pendulum (TWIP) mobile robots has been ongoing in a number of robotic laboratories around the world. In this paper, we consider a robust controller design for the TWIP mobile robot driving on uniform slopes. We use a 2 degree-of-freedom (DOF) model which is obtained by restricting the spinning motion in a 3 DOF motion dynamic equation. In order to design the robust controller guaranteeing stability of the TWIP mobile robot driving on inclined surface, we propose a sliding mode control based on the theory of variable structure systems and design a sliding surface using the theory of the linear quadratic regulation (LQR). For simulation, the dynamic model of the TWIP mobile robot is constructed using Mathworks' Simulink and the sliding mode control is also implemented using Simulink. From simulation results, we show that the proposed controller effectively controls the TWIP mobile robot driving on slopes.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.6
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• pp.516-526
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• 2016

This paper introduces a hovering-type autonomous underwater vehicle (AUV) developed for research and its fundamental motion performance results obtained by simulation and field test. The AUV can control its motion in four degrees of freedom (DOF) by means of its horizontal and vertical thrusters, and it is designed to provide a test-bed that facilitates ease of operation and experimentation. Prior to the field tests, six DOF equations of motion are developed, and a simulation program is constructed using MATLAB and Simulink to verify the essential motion performance of the designed vehicle. Furthermore, a proportional-integral-derivative (PID) controller and fuzzy PID controller are designed, and their performances are verified through a simulation. Field tests are performed to verify the motion performance of the AUV; way-point tracking is executed by the PID and fuzzy PID controllers. The results confirmed appropriate control performance under current disturbances.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.1
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• pp.170-180
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• 1986

본 연구에서는 2자유도 Hamiltonian 운동계에서 비선형 정규모우드(normal mode)들의 안정성을 예측하기 위한 제3의 운동상수를 선형계의 진동수비가 1:1이고 포텐셜이 4차항까지 우함수인 일반계에 적용하여 발전시켰다. 이는 Hamiltonian을 정규모우드로 바꾸는 B-G변환과 함수들을 부호처리함과 Poincare map을 이용하다. 비선형계에서 비선형상수에 따라 모우드가 bifurcate되며, 각각의 모우드 안정성은 제3의 운동상수와 Poincare map으로 정확히 판정할 수 있다는 결론을 얻었다.

• Journal of the Korea Society of Computer and Information
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• v.18 no.2
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• pp.149-156
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• 2013

In this paper, the Constitutional Court's ruling through the SNS was virtually guaranteed the freedom of election campaign through, though, still a large portion of campaign restrictions on public election law provisions exist to this forward in the election is likely to cause a lot of legal problems. In this paper, the Constitutional Court's ruling through the SNS was virtually guaranteed the freedom of election campaign through, though, still a large portion of campaign restrictions on public election law provisions exist to this forward in the election is likely to cause a lot of legal problems. Moreover, in the mean time the campaign and which in the course of the election campaign through the SNS, the infinite potential of the growing point than any point spread from the SNS and freedom of election campaign through public election law with regard to the limitation of the diffusion of false facts, awards, a number of problems are likely to occur. You've been in this business and disseminate false guilt disparage precandidacy for true-false, as well. He should be able to reach a specific goal you want to defeat through the dissemination of information which is specified as a crime for this strictly for the fact that disseminate false, rather than to interpret it is the judgment of the Court in that judgment against have been made. Therefore, this strict interpretation of the law and the need to revise or delete before I would like to discuss about. The legislation would repeal the cull of Ron sang first of all point out the issue through analytics. First, the purpose of the data protection Act provides limited interpretation to fit in this world of sin. Secondly, this sin is committed for the purpose of prevention, since the purpose of the objective in this case of sin and the need to interpret strictly. Why I am the Internet space in the case of so-called tweets from followers, this means in some cases done without a lot of the stars because of this, there will be a limit to the punishment of sin, this is obvious. And, in the long-awaited Constitutional Court ensures the freedom of election campaign through SNS and free election in the country, even in the limited sense interpretation opens the chapter of communication is needed. This ensured the freedom of expression will be highly this is a mature civil society that will be imperative.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.328-330
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• 2018

A floating body with a device that converts solar energy into electrical energy is moved by waves. To evaluate the safety of a floating body, measurement and interpretation of the float motion is required, which is generally based on 6 degrees of freedom motion. The 6 degree of freedom motion can be measured using MEMS (Micro-Electro Mechanical System), which features low power, small size and low cost. The key issue is, meanwhile, the low precision of the MEMS. In this study, the safety evaluation technique by analyzing the behavior of floating body using MEMS was examined. As a result of the study, it was found that the marine floating body can be modeled through the inertial measurement platform using the 3-axis accelerometer and the 3-axis gyroscope, and the safety of the float can be evaluated through this model.

• (The)Korea Educational Review
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• v.23 no.3
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• pp.117-142
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• 2017

The purpose of this study is to illustrate Richard Henry Tawney's idea of adult education among traditions of workers' education movement. The workers' education movement can be categorized into two streams. One tradition regards as the workers' education as a part of liberal education. The other tradition regards as it as a tool for social transformation. The former, which emphasizes the importance of liberal education in workers' education, had been developed in connection with the University Extension in England, and had a practical influence through the 'Workers' Educational Association(WEA)' organized by Mansbridge and other intellectuals. The latter, which emphasizes the social transformational function of education, conducted education in a form that is not clearly distinguished from propaganda, through the 'National Council of Labour College(NCLC)'. Tawney demonstrates the idea of adult education that synthesizes these two traditions, and this synthesization is related to his idea on equality. Tawney pursued socialism through democratic and non-violent way. He thought that adult education could contribute to the construction of socialism while at the same time conducting adult education based on liberal education. In other words, adult education based on liberal education, through rational understanding and discussion of the world, can contribute to social transformation. Tawney's idea of adult education provides practical implications for educationalists and educators who want progressive social change, and theoretically enriches educational research on the relationship between social transformation and education.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.285-290
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• 2004

Wave exciting force and moment generate the motions of a ship in waves. Since ship motion exerts the negative influences on a crew's operability, the safety of cargos, passenger's comfort, etc, the anti-rolling devices may be required to reduce such motion. In this paper, the dynamics of the anti-rolling devices such as passive and active moving weight stabilizer and anti-rolling tank, and fin stabilizer are mathematically modeled. While the effect of the motion of the anti-rolling device on a ship was taken into consideration in roll mode only in the past, the 6 DOF coupled equations of motion between a ship and the anti-rolling devices are constituted. Finally the motion of a ship with anti-rolling devices in waves is simulated through the developed simulation program.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.1
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• pp.16-27
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• 2002

A level-set method is used for analyzing the behaviors of gas bubbles in two fluids incompressible viscous flow domain. The governing equations are solved by using a finite volume method. The numerical results are verified by comparing with the experimental and other computational results. Computations for the deformations and motions of one or multi-bubbles in the flow domain with the initial undisturbed free interface are conducted. It can be seen that numerical results for different surface tension and density ratio arise very different behaviors of bubbles. When bubbles rise near the free interface, the free interface gives some great influence on the behaviors of bubbles. The present results computed by a level-set method give useful information about the properties of bubble motions and deformations.