• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.111-114
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• 2010

발사체 추진시스템에서 CC(Combustion Chamber) 산화제 개폐밸브는 액체산소를 연소기로 공급 및 차단함으로써 연소를 개시 및 중단시킬 뿐만 아니라, 정상운영 상태에서는 연소기 내 안정된 연소가 가능하도록 일정한 유량의 액체산소를 공급한다. 개발이 완료된 산화제 개폐밸브 EM(Engineering Model)의 주요 구성부의 성능향상을 위하여 전산구조해석을 이용한 중간플랜지, 밸브 입구의 립 부분의 설계 변경을 수행하였으며, 성능 시험을 통하여 설계변경에 의한 성능 향상을 최종확인 하였다.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권3호
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• pp.275-282
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• 2013

Applications such as vibration isolation, gravity compensation, pick-and-place machines, etc., would benefit from (long-stroke) cylindrical/tubular permanent magnet (PM) actuators with integrated passive gravity compensation to minimize the power consumption. As an example, in component placing (pick-and-place) machines on printed circuit boards, passive devices allow the powerless counteraction of translator including nozzles or tooling bits. In these applications, an increasing demand is arising for high-speed actuation with high precision and bandwidth capability mainly due to the placement head being at the foundation of the motion chain, hence, a large mass of this device will result in high force/power requirements for the driving mechanism (i.e. an H-bridge with three linear permanent magnet motors placed in an H-configuration). This paper investigates a tubular actuator topology combined with passive gravity compensation. These two functionalities are separately introduced, where the combination is verified using comprehensive three dimensional (3D) finite element analyses.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2002년도 동계 학술대회 논문집
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• pp.104-110
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• 2002

본 연구는 보행형 관리기의 손으로 전달되는 진동특성을 실험적으로 해석하고 평가하며 방진 방안을 제시할 목적으로 수행되었다. 관리기의 작업기 중에서 설문을 통해 사용 빈도가 높은 3개의 작업기(중경로터리, 중경제초기, 구굴기)를 선정하였고 각 작업기별 진동수준을 측정하였다. 진동 방지 방안에 대해서는 4개의 방진 장치(고무 패드, 방진 장갑, 핸들 방진 장치, 엔진 마운트)를 선정하여 각 방진 장치별 진동수준을 측정하였다. 방진 장치의 성능을 정확하게 비교하기 위해 진동의 측정은 진동수준이 가장 높은 구굴기에서 수행되었다. 실험결과에 의하면 관리기 작업이 작업자의 인체에 해를 끼칠 위험이 매우 크지만 이 결과는 작업자가 매일 3시간씩 관리기를 사용할 경우를 기준으로 설정한 값이기 때문에 실제로 관리기 사용일수가 많지 알은 대부분의 우리나라 사용자들에게 적용하는데는 한계가 있음을 밝힌다. 그렇다 하더라도 관리기의 주 사용자는 보행형 관리기 뿐만 아니라 보행형 경운기나 보행형 이앙기 등의 손으로 전달되는 진동이 심한 기계를 함께 사용하는 경우가 많음을 고려하면 방진 장치를 개발하거나 진동수준이 낮은 농작업기계를 개발하여 작업환경을 개선하는 조치가 필요하다고 생각한다. 그러므로 농작업기계에 대한 진동수준에 대한 종합적인 연구와 그에 대한 대책 마련이 지속적으로 수행되어야 할 것이다.

• 한국지반신소재학회논문집
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• 제5권2호
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• pp.23-30
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• 2006

본 연구는 환경진동으로 유발되는 진동 대책 중 전파 경로상에 방진구나 방진벽 등과 같은 진동차단벽을 설치했을 경우 차단벽의 재료를 방진구, 콘크리트, EPS, 철로 변화시켜 유한요소해석을 수행하여 진동을 가장 효율적으로 저감시킬 수 있는 재료 및 차단벽의 규모(타설심도, 차단벽두께, 진원으로부터의 거리)에 대하여 연구하였다. 본 연구 결과 방진구의 경우는 차단벽의 두께의 영향보다는 차단벽의 타설심도에 영향이 크고, 콘크리트의 경우에는 다른 방진벽의 방진효과에 비해 방진효과가 떨어진다. 또한 EPS의 경우는 타설심도 보다는 차단벽두께의 영향이 진동차단에 더 효과적임을 알 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.715-720
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• 2005

The rotating transmission is made up of belts, mass disks and gears. This precise piece of equipment is controlled electro-mechanically by the mote. and operation program. The control strategy and the transmission can be changed by belts' stiffness and change of the mass and gear. This transmission can be modeled as a rigid body, and also finds broad application in such diverse fields as machine tools, the cruise control system in automobiles, and control in the attitude and gimbals of spacecraft. The study of the rotating transmission excited by its base motion is not only able to predict the rotational performance, but obtain the fundamental data for vibration isolation. In this thesis, we studied the response abilities such as steady overshoot, undershoot and ect. and the response velocities such as rising time, settling time, and ect. in the rotating transmission through PD control experiment.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1776-1781
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• 2008

To reduce interior noise of running vehicles, a floating floor construction has been widely used in recent railway industry. Among the key factors of the floating floor design, dynamic stiffness is of most important in acoustical point of view. Sometimes hard rubber type supports have often been selected due to the other design constraints such as heavy load condition, durability of rubber element and its cost etc., even though it seems like the softer support, the better isolation of noise and vibration. In this paper two representative floor supports have been considered to evaluate their effectiveness in interior noise contribution: one is a soft rubber and another is a relatively hard one. From the measured dynamic stiffness of the specimens, equivalent stiffness of actual floating floor has been derived to use in the analytical models. Calculated air-borne and structure-borne noise insulation properties of the floating floors have been compared with experiments in prototype car. In full car model interior noise levels of running vehicles have been predicted to quantify the effectiveness of the two different floating support materials and verified through the measured inside noise levels of actual train as well. By comparison with difference of running noise levels two materials for floor support can be investigated quantitatively so that it could be applied in floating floor design.

• Structural Engineering and Mechanics
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• 제78권4호
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• pp.425-437
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• 2021

Under foundation shock mats have been used in the current practice in order to reduce/damp vibrations received by buildings through the surrounding environment. Although some investigations have been made on under foundation shock mats performance, their effectiveness in the reduction of railway induced-vibrations has not been fully studied, particularly with the consideration of underneath soil media. In this regard, this research is aimed at investigating performance of shock mat used beneath building foundation for reduction of railway induced-vibrations, taking into account soil-structure interaction. For this purpose, a 2D finite/infinite element model of a building and its surrounding soil media was developed. It includes an elastic soil media, a railway embankment, a shock mat, and the building. The model results were validated using an analytical solution reported in the literature. The performance of shock mats was examined by an extensive parametric analysis on the soil type, bedding modulus of shock mat and dominant excitation frequency. The results obtained indicated that although the shock mat can substantially reduce the building vibrations, its performance is significantly influenced by its underneath soil media. The softer the soil, the lower the shock mat efficiency. Also, as the train excitation frequency increases, a better performance of shock-mats is observed. A simplified model/method was developed for prediction of shock mat effectiveness in reduction of railway-induced vibrations, making use of the results obtained.

• Journal of Multimedia Information System
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• 제8권2호
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• pp.121-130
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• 2021

Foot bionic robot could be supported and towed through a series of discrete footholds and be adapted to rugged terrain through attitude adjustment. The vibration isolation of the robot could decouple the fuselage from foot-end trajectories, thus, the robot walked smoothly even if in a significant terrain. The gait programming and foot end trajectory algorithm were simulated. The quadruped robot of parallel five linkages with eight degrees of freedom were tested. The kinematics model of the robot was established by setting the corresponding coordinate system. The forward and inverse kinematics of both supporting and swinging legs were analyzed, and the angle function of single leg driving joint was obtained. The trajectory planning of both supporting and swinging phases was carried out, based on the control strategy of compound cycloid foot-end trajectory planning algorithm with zero impact. The single leg was simulated in Matlab with the established kinematic model. Finally, the walking mode of the robot was studied according to bionics principles. The diagonal gait was simulated and verified through the foot-end trajectory and the kinematics.

• 한국지진공학회논문집
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• 제26권2호
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• pp.95-103
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• 2022

In order to evaluate the earthquake safety of equipment in structures, it is essential to analyze the In-Structure Response Spectrum (ISRS). The ISRS has a peak value at the frequency corresponding to the structural vibration mode, but the frequency and amplitude at the peak can vary because of many uncertain parameters. There are several seismic design criteria for ISRS peak-broadening for fixed base structures. However, there are no suggested criteria for constructing the design ISRS of seismically isolated structures. The ISRS of isolated structures may change due to the major uncertainty parameter of the isolator, which is the shear stiffness of the isolator and the several uncertainty parameters caused by the nonlinear behavior of isolators. This study evaluated the effects on the ISRS due to the initial stiffness of the bi-linear curve of isolators and the variation of effective stiffness by the input ground motion intensity and intense motion duration. Analyzing a simplified structural model for isolated base structure confirmed that the ISRS at the frequency of structural mode was amplified and shifted. It was found that the uncertainty of the initial stiffness of isolators significantly affects the shape of ISRS. The variation caused by the intensity and duration of input ground motions was also evaluated. These results suggested several considerations for generating ISRS for seismically isolated structures.

• Earthquakes and Structures
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• 제24권5호
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• pp.333-343
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• 2023

Various seismic isolation and reduction devices have been applied to suppress the longitudinal vibration of continuous girder bridges. As representative devices, lead rubber bearing (LRB) and fluid viscous damper (FVD) might suffer from deterioration during the long-term service. This study aims to evaluate the impact of device deterioration on the seismic responses of continuous girder bridges and investigate the seismic behavior of deteriorated LRBs and FVDs. Seismic performance of a simplified bridge model was investigated, and the influence of device deterioration was evaluated by the coefficient of variation method. The contribution of LRB and FVD was assessed by the Sobol global sensitivity analysis method. Finally, the seismic behaviors of deteriorated LRBs and FVDs were discussed. The result shows that (i) the girder-pier relative displacement is the most sensitive to the changes in the deterioration level, (ii) the deterioration of FVD has a greater effect on the structural responses than that of LRB, (iii) FVD plays a major role in energy dissipation with a low degradation level while LRB is more essential in dissipating energy when suffering from high degradation level, (iv) the deteriorated devices are more likely to reach the ultimate state and thus be damaged.