• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.63-72
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• 2022

The purpose of this paper was to understand the dynamics of deployment of large mesh antennas, and to provide a numerical method for determining the dynamic stiffness and the driving forces for the design. The deployment structure was numerically modeled using the frame elements. The eigenvalue analysis was demonstrated, with respect to the folded and unfolded configurations of the antenna. A multibody dynamic model was formulated with Kane's equation, and simulated using the pseudo upper triangular decomposition (PUTD) method for resolving the constrained problem. Based on the multibody model, the kinetics of the deployment, the motor driving forces, and the feasibility of the designed deployment structure were investigated.

• Journal of Aerospace System Engineering
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• v.16 no.4
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• pp.68-76
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• 2022

The purpose of this paper was to design the cable networks for mesh reflector antennas, considering the flexibility of structures. An effective form-find methodology is proposed. The whole parts of the cable networks are described by the absolute nodal coordinate formulation. Additionally, nonlinear deformation of the cable can be obtained. The form-finding analysis of the reflector with standard configuration is performed, to validate the proposed methodology. The truss ring structure is numerically modeled using the frame elements. To consider the flexibility of the truss ring as well as the cable net structure, an iteration analysis between the truss ring and the cable net under tensional forces is also performed in the form-finding process. The finial configuration of the reflector with tensioned cable networks is demonstrated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.6
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• pp.717-725
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• 2004

A power generation systems are proposed to convert ambient mechanical vibration into electrical energy using cantilever-type piezoelectric materials. The vibration-based power device can be used for self-powered systems without batteries. This paper presents the theoretical analysis for the coupled equations of piezoelectric and structural motions and investigates the dynamic characteristics of the self-power system using transfer function method. The theoretical model is verified by the finite element analysis of the resonance frequency, the dynamic response of the structure and the sensor sensibility. Experimental results measured using a prototype system agree with the theoretical predictions. The system is shown to produce 34.5 ㎼ in average. Finally, we perform the optimal design for system variables to maximize output power.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.180-186
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• 2004

The simulator of a vehicle equipped with mechanical transmission and hydraulic accumulator type-braking energy regeneration system is developed using a PC. The simulator receives the shift lever position, the accelerator pedal angle and the brake pedal angle generated by the operator using the keyboard, updates the state variables of the energy regeneration system responding to the input signals, and draws the moving pictures of the accumulator piston and pump/motor plate angle every drawing time on the PC monitor. Also, the operator can observe the shift lever position, the accel pedal angle, brake pedal angle, pressures of accumulators, vehicle speed, hydraulic torque, engine torque and air brake torque representing the operation of braking energy regeneration system through the PC monitor every drawing time. The simulator can be a very useful tool to design and improve the braking energy regeneration system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.4
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• pp.289-309
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• 2014

A rotor blade is an important device that converts kinetic energy of wind into mechanical energy. Rotor blades affect the power performance, energy conversion efficiency, and loading and dynamic stability of wind turbines. Therefore, considering the characteristics of a wind turbine system is important for achieving optimal blade design. This study examined the general blade design procedure for a wind turbine system and aero-structure design results for a 2-MW class wind turbine blade (KR40.1b). As suggested above, a rotor blade cannot be designed independently, because its ultimate and fatigue loads are highly dependent on system operating conditions. Thus, a reference 2-MW wind turbine system was also developed for the system integrated load calculations. All calculations were performed in accordance with IEC 61400-1 and the KR guidelines for wind turbines.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.8
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• pp.2123-2138
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• 1994

A study on the dynamic mechanical properties of the high strength carbon fiber epoxy composite beam was carried out. The macromechanical model was used for the theoretical analysis of the symmetric laminated composite beam. The anisotropic plate theory and Bernoulli-Euler beam theory were used to predict the effective flexural elastic modulus and the specific damping capacity of laminated composite beam. The free flexural vibration and torsional vibration tests were carried out to determine the specific damping capacities of the unidirectional laminated composite beam. The vibration tests were performed in a vacuum chamber with laser vibrometer system and electromagnetic hammer to obtain accurate experimental data. From the computational and experimental results, it was found that the theoretical values with the macromechanical analysis and the experimental data of symmetric laminated composite beam were in good agreement.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.2
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• pp.203-209
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• 2015

Recently, the portion of electronic control in an engine system has been increasing with the aim of meeting the requirements of emissions and fuel efficiency of the engine system in the construction machinery industry. Correspondingly, the complexity of the engine management system (EMS) has increased. This study developed an engine HiLS system for reducing the cost and time required for function development for the EMS. The engine model for HiLS is composed of air, fuel, torque, and dynamometer models. Further, the mean value method is applied to the developed HiLS engine model. This model is validated by its application to a heavy-duty diesel engine equipped with an exhaust gas recirculation system and a turbocharger. Test results demonstrate that the model has accuracy greater than 90 and also verify the feasibility of the virtual calibration process.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.38-45
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• 1993

The feature based modeling approach is useful for post-CAD related works such as process planning and NC part programming. This paper describes the development of 'FeaTURN' system which is feature based NC part programming system for turning operation. The programming task in 'FeaTURN' system becomes easy and effective with the assistance of feature icons. The manufacturing attributes can be handled toghther with the features during input procedure. The cutter location data (CLD) is determined by the processor module. The post process module converts the CL data to machine control data (MCD). Also, the system graphically displays the tool path.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.866-867
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• 2023

기존의 무인 경로 로봇 시스템은 지형 제약과 높은 가격으로 인해 범용성에 한계를 갖는다. 이러한 한계를 극복하기 위해 철조망 위를 자율 주행하는 로봇 시스템(FPS, Fence Patrol System)을 소개하고, 하드웨어와 소프트웨어 측면에서 FPS 의 시스템 작동 원리를 설명한다. FPS 는 철조망 위에서 진동이 감지된 지역으로 이동해 객체를 탐지하고 추적하면서 관리자에게 전송한다. FPS 는 다양한 폭을 갖는 철조망 위에서 주행이 가능하고 완만한 곡률이 있는 철조망도 주행할 수 있도록 설계되었다. 이를 통해 지상 무인 경계 시스템의 한계를 해결하고 다양한 분야에 활용될 것으로 기대한다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.5
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• pp.111-120
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• 2021

A tractor is an agricultural machine that performs farm work, such as cultivation, soil preparation, loading, bailing, and transporting, through attached working implements. Farm work must be carried out on time per the growing season of crops. As a result, the reliability of a tractor's transmission is vital. Ideally, the transmission's design should reflect the actual load during agricultural work; however, configuring such a measurement system is time- and cost-intensive. The design and analysis of a transmission are, therefore, mainly performed by empirical methods. In this study, a tractor with a measurement system was used to measure the actual working load in the field. Its hydro-mechanical transmission was then analyzed using the measured load. It was found that the velocity factor, load distribution factor, lubrication factor, roughness factor, relative notch sensitivity factor, and life factor affect the gear strength of the transmission. Also, loading conditions have a significant influence on the reliability of the transmission. It is believed that transmission reliability can be enhanced by analyzing the actual load on the transmission, as performed in this study.