• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1511-1517
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• 2008

The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. The magneto-rheological fluid damper, which uses such characteristics of the fluid, generates shear force due to the fluid's cohesiveness. The core can be said to determine the magneto-rheological fluid damper's performance. This study uses the finite element analysis to compare the performance of different electromagnetic forces, which are affected by the shapes of the coil, and thus to find the optimum design for the core. In addition, as a step to construct a high-efficient damper, we suggest a type of damper that can control multiple coils and compares the performance of this damper and that of the standard damper by comparing the performance of their electro-magnetic fields.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.98-102
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• 2009

The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. To manufacture the magneto-rheological fluid damper that uses such characteristics of the fluid, a flow analysis of the inner damper was conducted to forecast the damper's capacity. In addition, using the finite element method software, analysis on the characteristics of electromagnetic field around the coil operation unit inside the damper. Based on the result of the analysis, a single core damper and a double core damper were built and tested for their dynamic function. Based on the result of the experiment, the propriety of the flow analysis was demonstrated, and the proposed model was verified.

• Journal of KSNVE
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• v.11 no.1
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• pp.141-146
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• 2001

This paper deals with an application of Magneto-Rheological (MR) fluid to a small size mount for precision equipment of automobiles. MR fluid is known as a class of functional fluids with controllable apparent viscosity of fluid by the applied magnetic field strength. A typical MR fluid is a suspension where pure iron particles of 1-20 (m in diameter are dispersed in a liquid such as mineral oil or silicone oil, at the concentration of 20 - 40 vol%. Electro magnetic coil is installed at the bottom of a variable-damping mount filled with MR fluid, and performance of the mount was investigated experimentally. Furthermore, the Properties of the MR Mount on experimental study were explained analytically by mechanical model of the MR mount.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.672-677
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• 1998

액체금속로 순환 냉각재인 전기전도성 나트륨 유체를 전자기적으로 구동시키는 선형유도 전자펌프의 유로내 과기유체역학적(MHD) 특성 분포를 해석적으로 계산하였다. 유로 내 반지름 방향의 좌표에 따라 유속, 점성력 및 전자기 구동력 둥을 계산하여 하트만 수(H$_{a}$ )에 따른 유체 특성의 변화를 그래프로 도시하였다. 하트만 수(H$_{a}$ )가 증가할수록 도전성 나트륨 유체의 유속 분포는 점점 평탄해지고 점성력은 전자기력에 비해 무시할 정도로 작은 값을 가짐을 알 수 있었다. 따라서 적지 않은 자기장에 의해 구동되는 전자펌프에 있어서 금속 유체는 마치 일정 두께의 금속 고체로 취급될 수 있음을 예측할 수 있었다.

• Journal of the Korean Magnetics Society
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• v.8 no.2
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• pp.93-98
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• 1998

Magnetic fluids have been used in the commercial area, e. g damping, sealing and hydrodynamic bearing. In this study, magnetic fluid was made for damping in loudspeaker. The magnetic fluids were snthesized by dispersing the magnetite powder which was obtained by precipitation method in Yubase oil. When the magnetic fluid was applied to a 6 cm tweeter, improvements of damping, centering and heat transger in a loudspeaker were noted. Also we compared the performance of the magnetic fluid with 20 % magnetite in the oil and the one of APG-815 (Niphon Ferrofluidic Co.)

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.291-297
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• 2018

Due to difficulty in minimally invasive surgery, training simulator is actively researched. A volumetric deformable organ is created by employing a shape-retaining chain-linked (S-chain) model to realize positioning a human organ model in virtual space. Since the main principle of the S-chain algorithm is that the repulsive force is proportional to the number of chain elements, the calculation time can be increased according to the magnitude of deformation. In this work, the advanced S-chain algorithm is used to calculate the repulsive torque according to spin motion. Finally, haptic architecture was constructed using this S-chain model by incorporating the virtual organ with a real master device, which allows the repulsive force and target position to be transferred to each other. The control performance of S-chain algorithm has been evaluated via experiment.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.1
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• pp.142-151
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• 1995

회전체의 자동밸런싱을 위하여 고안된 자기보상 동적균형기는 홈이파인 원판에 강구와 저점성유체를 지닌 구조체이다. 유도된 운동방정식으로 부터 자기보상 동적균형기의 작동조건을 조사하기 우하여 수치해석을 통한 동 특성을 검토하였다. 수치해석의 결과에 근거하여 임계속도보다 높은 범위에서는 자기보상 동적균형기는 정상작동을 보여주었다. 임계속도에서는 회전계의 균형이 강구와 점성유체와의 감쇠계수에 의존하였으나 임계속도보다 낮은 범위에서는 어떠한 조건에 대해서도 작동하지 않음을 알 수 있었다. 자동차 및 항공기에도 응용가은한 자기보상 동적균형기의 작동조건들을 본 논문에서 예시하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.22-28
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• 2009

Recently, there has been an active study about smart fluid to control the vibration, in which MR fluid is evaluated as most efficient because it can generate different bonding forces based on the intensity of the external magnetic fields. This paper attempts to find a mechanism that, under limited conditions during a clutch production that uses such dynamic characteristic, defects the maximum intensity of electromagnetism. Using the finite element analysis program, we predicted a change within the bonding force of the MR fluid occurring inside the clutch when it is subjected to an increased electric current. In addition, we analyzed the change in the magnetic intensity when the coil comprising the coil control center is switched to multiple lines from the standard single line, to find a mechanism that can maximize the effect. Based on this analysis, we developed the clutch and tested its function, hoping to widen future MR fluid's range of application.

• The Korean Journal of Rheology
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• v.11 no.2
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• pp.105-111
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• 1999

Dampers have been used to dissipate energy in mechanical systems. There are several types of dampers such as passive, active, and semi-active damper. Semi-active dampers have higher performance than passive ones and require less power to operate than active ones. Their damping characteristics can be changed properly for varying conditions. In this paper, we investigated the semi-active damper using Magneto-Rheological fluid. Magneto-Rheological fluid, which is one of controllable fluids, changes its damping and rheological characteristics from Newtonian fluid to Bingham fluid as the magnetic field is applied. It has several advantages such as high yield strength, low viscosity, robustness to impurities and wide temperature range of stability. If we designe a semi-active damper by using this material, we can not only design a simply structured damper but also expect rapid response. In this study, we propose several types of semi-active dampers which are designed and manufactured using Magneto-Rheological fluid and some problems encountered during their applications.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.464-467
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• 2002

This paper presents investigation of damping characteristics of squeeze mode type MR (magneto-Rheological) mount experimentally. Since damping property of the MR fluid is changed by variation of the applied magnetic field strength, squeeze mode type MR mount proposed in the study has variable damping characteristics according to the applied magnetic field strength. Impact and excitation tests were performed to investigate the dynamic properties of squeeze mode type MR mount. Responses of the mount were compared in proportion to the applied magnetic field strength. The experimental results show that the mount can effectively reduce vibration amplitude in a wide frequency range by changing the applied magnetic field strength.