• 드라이브 ㆍ 컨트롤
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• 제16권1호
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• pp.7-13
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• 2019

The objective of this study was to present a damped pneumatic suspension, a bike fork suspension, which can adapt itself to incoming road excitations is presented in this paper. It consists of a hydraulic damper and a pneumatic spring in parallel with a linear spring. The study also proposed a variable and switchable orifice, in the hydraulic damper, to select appropriate damping property. Hydraulic-pneumatic circuit model for the bike fork suspension was established based on AMESim, in order to predict its performance. In addition, elastic-damping characteristics of the fork such as spring constant and viscous damping coefficient were computed and compared, for validation, with those evaluated by experiment using the universal test machine. Through simulation analysis and test, it was established that the hydraulic-pneumatic circuit model is effective and practical for development of future MTB suspensions.

• 제어로봇시스템학회논문지
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• 제5권2호
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• pp.208-219
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• 1999

Springs have been employed in a wide range of mechanical systems. This work deals with the concept of an adaptable spring mechanism which can arbitrarily modulate its spring characteristics. The adaptable spring is desired for enhancing performances of various mechanical systems employing springs. We demonstrate that such adaptable springs can be realized by adapting anthropomorphic musculoskeletal structures of the human upper-extremity, which possesses highly nonlinear kinematic-coupling among redundant muscles existing in its structures. This phenomenon has been explained by several human arm models. Based on the analysis results, we propose multi-degree-of-freedom spring mechanisms resembling the musculoskeletal structure of the human upper-extremity, and verifiy the applicability of these mechanisms through simulation.

• International Journal of Automotive Technology
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• 제6권5호
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• pp.483-489
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• 2005

Based on a two-degree of freedom vehicle model, this paper investigates ride comfort for a heavy off-road vehicle mounted a nonlinear hydropneumatic spring, which is influenced by nonlinear stiffness and damping characteristics of the hydropneumatic spring. Especially, the damping force is derived by applying H. Blasius formula in modeling process according to the real physical structure of the hydropneumatic spring, and the established model of nonlinear stiffness characteristics have been validated by experiments. Furthermore, the effects of parameter variations of the hydropneumatic spring, such as initial charge pressure and damping coefficient, on body acceleration, suspension deflection and dynamic tire deflection are also investigated.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.471-478
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• 2006

This paper presents the results of experimental studies of the mechanical characteristics of the Coil Spring and Viscous Damper system. The Coil Spring and Viscous Damper systems were selected for the isolation of Emergency Diesel Generator (EDG) which is located in Nuclear Power Plant (NPP). The Coil Spring and Viscous Damper systems were developed for, the operating vibration isolation and seismic isolation for scaled Model EDG System. The damping properties of the viscous damper changes as the variation of velocity. As a results, nonlinear damping characteristics of viscous damper system were evaluated.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2228-2236
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• 2002

The axial piston pump by which the mechanical energy is converted into hydraulic energy has been widely used in a press, a injection molding machine and construction equipments due to the high specific power compared to the electric power system. In this paper, the one-piece shoe holder spring of the axial piston pump to simplify its structure and reduce this manufacturing cost was designed and tested. The finite element analyses using the 3-D shell element and contact element were performed to determine the thickness, width and initial angle of the shoe holder spring. Also, the compressive tests of the shoe holder spring were performed and their results were compared with those of the finite element analysis. Also, the performance and endurance limit of axial piston pump with the shoe holder spring were tested and evaluated.

• 한국정밀공학회지
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• 제26권2호
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• pp.94-100
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• 2009

In diesel engines, it is inevitable that the torsional vibration is produced by the fluctuation of engine torque. Therefore, it is necessary to establish preventive measures to diminish the torsional vibration. The sleeve spring type damper is one of the preventive measures for reducing the torsional vibration. In this study, a closed form equation to predict spring constant of the sleeve spring and torsional characteristic of the torsional vibration damper was proposed to calculate stiffness of the damper and verified their availability through the finite element analysis. The theoretical values have a good agreement with the results obtained by the finite element analysis. The results obtained from the equation derived enable the designers in actual fields to be more efficient.

• 한국정밀공학회지
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• 제33권6호
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• pp.477-483
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• 2016

The spring-back and bow phenomenon in the roll forming process are important factors regarding the accuracy of evaluation of production goods. The purpose of this study was to determine the influence of spring-back and bow phenomenon according to the main variables (forming velocity and roll gap). The material of the forming sheet was high tension steel (SPFH 590), which has been used commonly in recent years. In order to accurately measure the spring-back and bow phenomenon, the forming sheet was formed into a V-shape. The study was applied to OFAT (One Factor at a Time) experimentation, with respect to the experimental variables (the forming speed and the roll gap). In the experimental results, the forming speed had a small influence on the spring-back and bow phenomenon. However, the roll gap had a greater influence on the springback and the bow phenomenon, as opposed to the forming speed.

• 한국정밀공학회지
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• 제17권10호
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• pp.95-101
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• 2000

The purpose of this study is to develop an improved measuring system, which allows for effectively measure spring clamping forces. This system consists of eight or twelve measuring points in order to acquire the clamping force distribution of the whole range of spring clamp. Each measuring point consists of load cells equipped with 4 strain gauges. Using different bearings, we calibrate the roundness of the measuring points. For quality control and database construction, a software system is established. furthermore, uncertainty is calculated to validate the confidence of this system. Various experiments confirm the effectiveness of this measuring system.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.118-126
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• 2003

In the present study, the residual stresses can have a significant on the life of structural engineering components. Residual stresses are created by the surface treatment such as shot peening or deep rolling. The objective of this experimental investigation is to study the influence of friction and wear characteristics due to residual stress under dry sliding condition. Friction and wear data were obtained with a specially designed tribometer. Test specimens were made of SUP9(leaf spring material) after they were created residual stress by shot peening treatment. Residual stress profiles were measured at surface by means of the X-ray diffraction. Sliding tests were carried out different contact pressure and same sliding velocity 0.035m/s(50rpm). Leaf spring assembly test used to strain gauge sticked on leaf spring specimen in order to measure interleaf friction of leaf spring. Therefore, we were obtained hysteresis curve. As the residual stresses of surfaces increased, coefficient of friction and wear volume are decreased, but the residual stresses of surfaces are high, and consequently wear volume do not decreased. Coefficient of friction obtained from leaf spring assembly test is lower than that obtained from sliding test. From the results, structural engineering components reduce coefficient of friction and resistant wear in order to have residual stresses themselves.

• 항공우주시스템공학회지
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• 제9권2호
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• pp.7-12
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• 2015

In this paper, we report a non-explosive separation device for a small satellite which utilize a shape memory alloy actuator and spring clamp. In order to increase the preload, the proposed device employs spring clamp that can generate high toque when the shape memory alloy actuator makes the cylinder key unlatch a holding ball effectively. Owing to simple design of separation device configuration, we could obtain good repeatability(up to 30 times activation). Conclusively, we could develop a non-explosive separation device which can reliably activate within 1.2 sec under high preload(up to 300kgf).