• Journal of Biosystems Engineering
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• v.25 no.2
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• pp.79-88
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• 2000

Effects on tractive performance of design parameters of cage wheel as a traction aid to driving tires of tractor in wet paddy field were investigated experimentally. an experimental cage wheel was designed so that the design parameters such as wheel diameter, wheel width, lug pitch and lug angle could be varied during traction test, The traction test was conducted in two different types of wet paddy field ; shallow and deep harpan fields . Experimental results showed that tractive performance is affected by both soil conditions and the design parameters. A considerable improvement on the tractive performance was obtained by using a cage wheel with 45$^{\circ}$ lug angle in shallow hardpan and smaller lug pitch in deep hardpan. The diameter of cage wheel was mostly influential to the tractive performance both in shallow and deep hardpans.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.836-839
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• 2003

In this paper, we briefly introduce the test bench and test method of RWA micro-vibration. TAMAM RWA (Reaction Wheel Assembly) micro-vibration was measured on a KISTLER dynamic plate which can measure time signals of three orthogonal forces and torques simultaneously up to 400Hz, and test data was analyzed. Measured data were evaluated with respect to the wheel spin rate and the static/dynamic unbalances were estimated from the extracted first harmonic component. The estimated static and dynamic unbalances were 0.79gㆍcm and 17.4gㆍ$\textrm{cm}^2$ respectively. The resonance mode and two rocking modes were observed as a results of its frequency analysis. Several higher order harmonic components were observed, which comes from its rotor shape as well as the wheel bearing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.612-617
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• 2014

It is generally known that the automotive road wheel involves the non-proportional multiaxial loading condition, therefore the measuring dynamic stress and strain in driving state is very important to predict an endurance characteristic of the automotive road wheel. In this study, the ultimate driving test using F1 circuit with respect to 2 kinds of velocity conditions have been carried out in order to measure dynamic stress, strain of the wheel and acceleration of a vehicle. Based on the measured results, the characteristics of dynamic stress generation have been analyzed, and factors which have effect on the dynamic stress generation have been studied.

• Journal of Aerospace System Engineering
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• v.2 no.1
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• pp.13-16
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• 2008

The line of sight(LOS) is affected by the vibration of spacecraft. It is necessary to predict the effect of disturbance on LOS stability. Reaction wheel assembly is anticipated to be the largest disturbance source on spacecraft. The disturbance which is occurred mainly due to the mass imbalance is analyzed with harmonic numbers. The accuracy and stability are verified by probability density function with dynamic equation of the satellite motion.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.31.4-32
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• 2010

저궤도 위성의 주요 부하는 대부분 잉여성을 지니게 설계되며, 위성 본체의 전압 및 전류의 변화에 대한 보호를 위해 밸러스트 회로가 추가적으로 요구 될 수 있다. 이중 휠은 위성의 기동에 사용되는 대용량 부하로 안정화를 위해 밸러스트회로의 설계가 추가적으로 필요하다. 이 논문에서는 이를 위해 위성의 운용상 발생할 수 있는 본체 전압의 Transition 조건 및 밸러스트회로의 모델링 분석을 진행하였으며, 모의실험을 위한 시뮬레이션 프로그램은 Matlab/silulink 및 PSIM을 이용하였다. 최종적으로 본체 전압의 변동 조건을 Inrush, Major/minor 및 Step/Frequency 부하 변동으로 나누었고, 2-port 모델링을 통해 밸러스트 회로의 구성 및 외란에 따른 영향성을 분석하고, 시뮬레이션을 통하여 검증 하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.2
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• pp.129-137
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• 2000

In the prototype stage of a car developing program, the efficiency of trouble shooting is an important factor to be considered. Structural modifications by the design sensitivity analysis are applied to a steering wheel system for improving the idle vibration of the prototype passenger car. For the design sensitivity analysis, the experimental modal analysis for the steering system attached to a body-in-white is fulfilled and the modal parameters extracted from the experimental data are used to predict the effect of structural modification, The design sensitivity results rank the locations to be reinforced in terms of frequency variation. The modification of steering system according to the sensitivity analysis results shifted the resonant frequency of the system effectively. In addition, the idle test of the car after the structural modifications f steering system shows that the proposed method can reduce vibration of the steering wheel efficiently.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.2
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• pp.58-65
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• 2021

Most pipe-inspection robots have fixed sizes and use a wired cable system. Pipelines are generally composed of various structures, including bent pipes, vertical pipes, branch pipes, and holes, and it is difficult to explore the insides of such modular piping structures. In an offshore plant pipeline, a robot that can pass through the pipe hole in the downward direction or avoid obstacles, such as a measuring instruments, has not been introduced yet. In this study, an inspection robot that can travel through most pipelines in offshore plants is proposed. This robot uses mecanum wheels; upward, downward, and rotary motion; and a novel rotatable mechanism. Moreover, the robot is designed to be compact and lightweight to include additional devices in the middle.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.3
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• pp.199-205
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• 2014

Purpose: The purpose of this study was to evaluate the transmission of candida in denture by dental polishing lathe. Materials and Methods: Maxillary complete dentures made from the same model were infected with Candida albicans. The infected dentures were polished by dental polishing lathe with sterile pumice and distilled water. And then sterile maxillary complete dentures were polished with same method. Polishing surface was wiped with a cotton swab and the sample was checked for Candida albicans. The polishing wheel at room temperature was checked for Candida albicans every 24 hours for 3 days. Results: A considerable number of Candida was found on the polished sterile dentures. And the Candida albicans in polishing wheel was detected at up to two days. Conclusion: An anti-infection measure is urgently needed when dental polishing lathe is used for denture polishing, because of the possibility of fungal infection.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.2
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• pp.125-130
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• 2013

According to the law revision of TPMS mounting obligations in Korea, researches about energy harvester which is the alternative of the battery are actively performed by many groups. Because WSN (Wireless Sensor Network) has the proposition of "Install and forget" and the power supplier also has the same performance as the vehicle's lifetime. In this paper, electromagnetic induction type of energy harvester through the relative motion between the rotating wheel and the fixed brake disc is introduced by using the most efficient source as the rotating motion in the view of vehicle's mechanism. The coil on the wheel and the permanent magnet at the brake disc are arranged in several ways. These various arrangements are the number of coil turns are consisted of design variables. By using the orthogonal array to reduce the experimental cost, the optimal composition is verified through the experiment. Finally the validity of the module is considered by measuring the level of storable electrical energy.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.5
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• pp.65-73
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• 2004

CMG(Control Momentum Gyro) is a control device being used for spacecraft attitude control constructing relatively large amount of torque compared to conventional body-fixed reaction wheels. The CMG produces gyroscopic control torque by continuously varying the angular momentum vector direction with respect to the spacecraft body. The VSCMG(Variable Speed Control Momentum Gyro) has favorable advantages with variable speed to lead to better control authority as well as singularity avoidance capability. Attitude dynamics with a VSCMG mounted on a two-axis gimbal system are derived in this study. The dynamic equation may be considered as an extension of the single-axis counterpart. Also, a feedback control law design is addressed in conjunction with the dynamic equations of motion.