• Journal of Microbiology and Biotechnology
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• v.3 no.3
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• pp.209-213
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• 1993

The flow behavior of the mycelial broth of glucoamylase hyperproducer Asp. niger No. PFST-38 for the production of glucoamylase were studied. The mycelial broth followed Bingham-pseudoplastic flow model described by Herschel-Bulkley equation. The yield stress increased with the increase in mycelial concentration. The dependency of the consistency index and the flow behavior index on the mycelial concentration could be expressed by a linear relationship. The consistency index increased proportionally with the mycelial concentration while the flow behavior index decreased with the increase in mycelial concentration. The flow property of the broth was related to the morphological data obtain in the previous study. The changes in apparent viscosity of the broth could be expressed as a function of the hyphal thickness as shown below.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.165-170
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• 2001

This paper presents performance analysis of two-linked robot system using ER (electro rheological) valve actuators. An ER fluid consisting of soluble chemical starches (particles) and silicone oil is made and its field-dependent yield stress is experimentally distilled using electro-viscometer. From this result, the design parameters of ER valve are determined. Based on parameter study, an ER valve system is designed and manufactured. Furthermore, the measured pressure drop is compared with predicted one obtained from the Bingham model. Following the evaluation of field-dependent pressure drop of ER valve, a two-linked robot system with two ER valve actuators is then constructed and its governing equation of motion is derived. From this equation, PID controller is established. Consequently, control performances of the proposed two-linked robot system featuring ER valve are evaluated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.543-546
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• 1997

The purpose of this study is to investigate the ERSU(Electr0-Rheological Suspension IJnit) and some progress of damping force characteristic of a ERSU. This paper describes overall construction of th'e system design and the manufacturing of ERSU. A model of the ERSU is made by using electric field dependent on Bingham properities of ER fluid. In this paper. the ERSU is designed and manufactured for a light ground tracked vehicle. From the results, it is shown that the damping performance of ERSLJ is better than that of a passive suspension unit. This experimental study might be very useful for the simulat~on and the design of semi-active suspension units.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.323-327
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• 2001

Electrorheological(ER) and magnetorheological(MR) fluids have a unique ability to increase the dynamic yield stress of the fluid substantially when electric or magnetic field is applied. Controllable fluids such as ER and MR fluids have received considerable attention as several components of engineering devices. One of them is a smart impact damper using ER/MR fluids. Impact damper system can be used in the joint mechanism of railroad vehicle, protection equipment of elevator's drop, and launch equipment of aircraft. This paper presents the results of an analytical study of the performance of a smart impact damper to suppress vibration during impact excitation. The damping capabilities of MR impact damper for variable applied current are analyzed using Bingham model under sudden impact load.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.421-428
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• 2005

In this paper, the performance of a toggle brace-MR damper system is evaluated for the control of the structure excited by earthquake load and the non-linearity of the toggle system is investigated. Considering that the control force of MR damper described by Bingham model is a function of velocity, velocity amplification factor by toggle brace system is calculated and the effect of toggle configuration on the amplification factor is also evaluated. Numerical results show that the control performance can be largely enhanced using toggle brace system especially for the case that the MR damper installed with conventional brace system such as Chevron and diagonal cannot provide enough control force under severe earthquake load.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.47-56
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• 1997

This paper presents the vibration control of an engine mount featuring an ER(electro-rheological) fluid. The Bingham properties of the ER fluid to be employed to the ER engine mount are experimentally obtained through Coeutte type viscometer. The ER engine mount is devised ant its governing equation is derived. After evaluating the performance of the ER engine mount on the basis of the mathematical model, the novel type of the ER engine mount is then designed and manufactured. The electric field-dependent transmissibility of the ER engine mount is evaluated by changing the particle concentration and the electrode gap size. To investigate the control performance of the ER engine mount, neuro-control algorithm is adopted. It is shown that the proposed ER engine mount has prominent capabilities of controlling the damping force by tuning the electric fields and excellent vibration isolation performance.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.3
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• pp.7-13
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• 1998

This paper presents a new concept of a commercial vehicle seat suspension system. The proposed suspension system features an ER(electro-rheological)damper which can produce continuously tunable damping forces by control elecric fields. A dynamic model of the ER damper is first achieved by incorporating Bingham property of the ER fluid, followed by the formulation of governing equations of motion for the suspension system The effectiveness of the proposed ER seat suspension system is evaluated by investigating vibration with respect to sinusoidal inputs.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.998-999
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• 2014

This paper proposes a method for damping force modeling of magnetorheological (MR) damper featuring bypass hole. After describing configuration and of the MR damper, a damping force modeling of the MR damper is derived based on Bingham model of MR fluid. MR damper consists of piston, accumulator, gap, bypass hole and coil. Damping force is consists of spring force induced by accumulator, viscous force induced at gap and bypass hole, and controllable force induced at gap.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.394-399
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• 1997

This paper presents a new concept of a semi-active suspension system for a commercial vehicle seat. The proposed suspension system features an ER(electro-rheological) damper which can produce continuously tunable damping forces by control electric fields. A dynamic model of the ER damper is first achieved by incorporating Bingham property of the ER fluid, followed by the formulation of governing equations of motion for the suspension system. A sliding mode controller is then designed on the basis of the hyper-plane sliding mode scheme. The effectiveness of the proposed control system is evaluated by investigating control performance for vibration isolation.

• Journal of the Korea Institute of Building Construction
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• v.11 no.4
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• pp.387-395
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• 2011

In the construction of tall-building, concrete pumping influences the success of the project. In order to establish pumping technology for high speed construction of tall building, study for quantitative evaluation of flow characteristics and pumpability should be conducted. So in this study, the characteristics including the inner pipe pressure, rheological properties of concrete and mortar through the continuous pumping test were evaluated. Then we analyzed the relations between rheological properties and pumpability. In the result of test, there are high correlations between the rheological characteristics which represented by yield stress and plastic viscosity and pressure loss with pipe length. Also, we estimated pressure loss according to conditions of concrete mix and pumping through the evaluation of inner pipe friction.