• 전자공학회논문지SC
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• 제44권4호통권316호
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• pp.35-41
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• 2007

본 논문에서는 한 바퀴로 구동하는 로봇 GYROBO을 제작하고 하드웨어를 구현하였다. 한 바퀴로 구동하는 로봇은 디스크와 같은 모양이고 자이로 움직임에 의해 균형을 잡는다. GYROBO는 스핀 모터, 기울기 모터, 그리고 드라이브 모터 등 3개의 구동기로 구성되어 있다. 스핀 모터는 고속으로 플라이휠을 구동하여 로봇이 균형을 잡을 수 있도록 한다. 딜트 로터는 자이로 움직임에 따라 로봇의 조향을 조절한다. 드라이브모터는 종방향 움직임을 조정한다. 몇 개의 모델을 디자인하였다. GYROBO의 움직임을 실험을 통해 검증하였다.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3732-3744
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• 2022

To investigate the effects of ocean conditions on the thermal stress and deformation caused by thermal stratification of a pressurizer surge line in a floating nuclear power plant (FNPP), the finite element simulation platform ANSYS Workbench is utilized to conduct the fluid-solid-thermal coupling transient analysis of the surge line under normal "wave-out" condition (no motion) and under ocean conditions (rolling and pitching), generating the transient response characteristics of temperature distribution, thermal stress and thermal deformation inside the surge line. By comparing the calculated results for the three motion conditions, it is found that ocean conditions can significantly improve the thermal stratification phenomenon within the surge line, but may also result in periodic oscillations in the temperature, thermal stress, and thermal deformation of the surge line. Parts of the surge line that are more susceptible to thermal fatigue damage or failure are determined. According to calculation results, the improvements are recommended for pipeline structure to reduce the effects of thermal oscillation caused by ocean conditions. The analysis method used in this study is beneficial for designing and optimizing the pipeline structure of a floating nuclear power plant, as well as for increasing its safety.

• 한국항해항만학회지
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• 제29권10호
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• pp.847-852
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• 2005

본 연구에서는 선박의 항해 안전성과 정박 중인 선박의 계류 안전성 평가에 기초가 되는 선체운동 평가를 위한 다목적 계측시스템을 개발하는데 있다. 다목적 계측시스템은 선박에 탑재되어 외력에 의해 발생하는 동적 동요를 계측 및 분석하기 위해 상하, 좌우, 전후방향의 가속도량을 측정하는 3축 가속도 계측기를 포함하여, 방위 센서, 2축 경사계 및 초음파 변위계로 구성하였다. 선박의 항해 및 계류 안전성을 종합적으로 평가하기 위해서는 특정 센서를 이용, 선체운동을 실시간으로 측정하여 내항성능 평가 시스템과 항해 또는 정박 중인 선박의 상태에 관한 선박 데이터베이스 시스템을 이용하여 평가한다. 개발된 다목적 계측시스템은 해상에서의 전복사고 분석, 선박 출입항 통제, 부두에서의 하역작업 통제, 조선소에서의 내항성능 및 안전설계에 있어서도 적용이 가능하리라 본다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 Asia Navigation Conference
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• pp.134-143
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• 2006

Out of all types of motions the critical motions leading to capsize is roll. The dynamic amplification in case of roll motion may be large for ships as roll natural frequency generally falls within the frequency range of wave energy spectrum typical used for estimation of motion spectrum. Roll motion is highly non-linear in nature. Den are various representations of non-linear damping and restoring available in literature. In this paper an uncoupled non-linear roll equations with three representation of damping and cubic restoring term is solved using a perturbation technique. Damping moment representations are linear plus quadratic velocity damping, angle dependant damping and linear plus cubic velocity dependant damping. Numerical value of linear damping coefficient is almost same for all types but non-linear damping is different. Linear and non-linear damping coefficients are obtained form free roll decay tests. External rolling moment is assumed as deterministic with sinusoidal form. Maximum roll amplitude of non-linear roll equation with various representations of damping is calculated using analytical procedure and compared with experimental results, which are obtained form forced tests in regular waves by varying frequency with three wave heights. Experiments indicate influence of non-linearity at resonance frequency. Both experiment and analytical results indicates increase in maximum roll amplitude with wave slope at resonance. Analytical results are compared with experiment results which indicate maximum roll amplitude analytically obtained with angle dependent and cubic velocity damping are equal and difference from experiments with these damping are less compared to non-linear equation with quadratic velocity damping.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 추계학술대회 논문집
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• pp.69-74
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• 2005

본 연구에서는 선박의 항해 안전성과 정박 중인 선박의 계류 안전성 평가에 기초가 되는 선체운동 평가를 위한 다목적 계측시스템을 개발 하는데 있다. 다목적 계측시스템은 선박에 탑재되어 외력에 의해 발생하는 동적 동요를 계측 및 분석하기 위해 상하, 좌우, 전후방향의 가속도량을 측정하는 3축 가속도 계측기를 포함하여, 방위 센서, 2축 경사계 및 초음파 변위계로 구성하였다. 선박의 항해 및 계류 안전성을 종합적으로 평가하기 위해서는 특정 센서를 이용 선체운동을 실시간으로 측정하여 내항성능 평가 시스템과 항해 또는 정박 중인 선박의 상태에 관한 선박 데이터베이스 시스템을 이용하여 평가한다. 개발된 다목적 계측시스템은 해상에서의 전복사고 분석, 선박 출입항 통제, 부두에서의 하역작업 통제, 조선소에서의 내항성능 및 안전설계에 있어서도 적용이 가능하리라 본다.

• 한국정밀공학회지
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• 제28권1호
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• pp.11-18
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• 2011

A worm screw is widely used in a geared motor unit for motion conversion from rotation to linear. For mass production of a high quality worm, the current rolling process is substituted with the milling process. Since the milling process enables the integration of all operations of worm manufacturing on a CNC(Computer Numerical Control) lathe, productivity can be remarkably improved. In this study, the tooling system for side milling on a CNC lathe to improve machinability is developed. However, the cutting tool-workpiece interference is important factors to be considered for producing high quality worms. For adaptability of various worms machining, the tool-workpiece interference simulation system based on a tool-tip trajectory model is developed. The developed simulation system is verified through several kinds of worms and experimental results.

• 제어로봇시스템학회논문지
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• 제6권2호
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• pp.146-154
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• 2000

An $H\infty$ controller is designed for active suspensions of vehicles using 7-degree-of-freedom full-car model. Its performance robustness as well as stability robustness to system parameter variations and unmodelled dynamics are assured through the $\mu$-framework. The performance of the $H\infty$ controller is compared with that of a LQC controller in compute simulations. From the simulations it is found that the active suspension with the $H\infty$ controller reduces the acceleration and motion of the sprung mass in the heaving rolling and pitching directions when the car is driven on a normal road or through an asymmetric bump. The suspension stroke and the road holding capability are also improved with a relatively small level of power consumption. Overall the $H\infty$ controller shows a more robust performance than that of the LQG design.

• 로봇학회논문지
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• 제8권4호
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• pp.229-237
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• 2013

In this paper, we report a self-balancing robot wheelchair which has the capability of keeping upright posture regardless of the terrain inclination in terms of the three dimensional balancing motion. It has the mobility of five degrees of freedom, where pitching, yawing, and forward motions are generated by the two-wheeled inverted pendulum mechanism and the rolling and vertical motions are implemented by the movement of the tilting mechanism. Several design considerations are suggested for the sliding type vehicle body, wheel actuator module, tilting actuator module, power and control system, and the riding module.

• 대한기계학회논문집A
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• 제24권8호
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• pp.1991-1999
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• 2000

This research has been performed to reveal the hysteresis phenomena of the hunting motion in a railway passenger car having a bolster. Since linear analysis can not explain them, bifurcation analysis is used to predict its outbreak velocities in this paper. However bifurcation analysis is attended with huge computing time, thus this research proposes more effective numerical algorithm to reduce it than previous researches. Stability of periodic solution is obtained by adapting of Floquet theory while stability of equilibrium solutions is obtained by eigen-value analysis. As a result, linear and nonlinear critical speed are acquired. Full scale roller rig test is carried out for the validation of the numerical result. Finally, it is certified that there are many similarities between numerical and test results.

• Advances in Computational Design
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• 제5권3호
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• pp.261-276
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• 2020

The reasonable layout of vacuum cleaner can effectively improve the collection efficiency of iron filings generated in the process of steel production. Therefore, in this study, the CFD-DEM coupling model and two-fluid model are used to calculate the iron filings collection efficiency of vacuum cleaner with different inclination/cross-sectional area, pressure drop and inlet angle. The results are as follows: The CFD-DEM coupling method can truly reflect the motion mode of iron filings in pneumatic conveying. Considering the instability and the decline of the growth rate of iron filings collection efficiency caused by high pressure drop, the layout of 75° inclination is suggested, and the optimal pressure drop is 100Pa. The optimal simulation results based on two-fluid model show that when the inlet angle and pressure drop are in the range of 45°~65° and 70Pa~100Pa, larger mass flow rate of iron filings can be obtained. It is hoped that the simulation results can offer some suggestion to the layout of vacuum cleaner in the rolling mill.