• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.342-349
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• 2018

Polystyrene (PS) was coated on carbonyl iron (CI) particles via dispersion polymerization to produce core-shell structured CI/PS particles and adopted as magnetorheological (MR) material. Two MR fluids were prepared by dispersing CI/PS and CI particles in silicone oil. Their MR and tribological properties were investigated using a rheometer and a reciprocating friction and wear tester, respectively. Experimental data showed that tribological properties of MR fluid based on CI/PS particles are significantly enhanced compared to those of CI based MR fluid. Sedimentation problem of CI/PS MR fluid was also expected to be improved due to relatively lower density of CI/PS particles.

• 한국지진공학회논문집
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• 제9권2호통권42호
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• pp.7-15
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• 2005

본 연구에서는 하이브리드 면진장치가 설치된 단자유도 구조물의 동적거동을 예측할 수 있는 수치해석모델을 제안한다. 하이브리드 면진장치는 MR 감쇠기와 마찰진자시스템(FPS)으로 구성된다. MR감쇠기의 동적거동을 모형화하기 위하여 뉴로-퍼지 모델을 사용한다. 다양한 변위, 속도, 전압의 조합을 사용하여 MR 감쇠기의 성능실험을 수행한 후 얻어진 데이터를 이용하여 MR 감쇠기 뉴로-퍼지 모델을 ANFIS로 학습시킨다. FPS의 모형화는 본 연구에서 유도한 비선형 모델식에 근거하여 뉴로-퍼지 모형화방법을 사용하여 이루어진다. 본 연구에서는 MR 감쇠기로 전달되는 제어전압을 조절하기 위하여 퍼지논리제어기를 사용한다. 다양한 지진하중을 사용한 진동대 실험을 통하여 얻은 실험체의 동적응답과와 뉴로-퍼지 모형화방법을 사용한 수치해석의 결과를 비교한다. 뉴로-퍼지 모델을 사용하여 MR 감쇠기와 FPS를 모형화해서 수치해석을 수행한 결과 하이브리드 면진장치의 동적거동을 매우 정확하게 예측할 수 있었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.210-215
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• 2002

MR(Magnetorheogical) fluid composed of fine iron powders dispersed in silicon oil is utilized to many smart structures and devices because of its significant rheological property change by the application of an external magnetic field. When we deal with the shock wave attenuation of warship structures, we should be able to characterize the high frequency behavior of MR fluids. So far, however, many efforts have been focused on the material characterization of MR fluids at low frequencies below 100Hz. In this paper, the MR fluid property characterization at high frequency region is performed. An experimental setup based on wave transmission technique is made and the storage modulus as well as the loss modulus of MR fluids are found from the measured data of speed sound and attenuation. Details of the experiment are addressed and the obtained storage and loss moduli are addressed at $50kHz{\sim}100kHz$.

• 한국소음진동공학회논문집
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• 제18권2호
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• pp.255-262
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• 2008

In this study, seismic response control performance of decentralized response-dependent MR damper which generates the control force using only the response of damper-installed floor, was experimentally investigated through the tests of a full-scale structure installed with large MR dampers. The performance of the decentralized control algorithm was compared to those of the centralized ones such as Lyapunov, modulated homogeneous friction, and clipped-optimal control. Hybrid mass damper were controlled to induce seismic response of the full-scale structure under El Centro earthquake. Experimental results indicated that the proposed decentralized MR damper provided superior or equivalent performance to centralized one in spite of using damper-installed floor response for calculating input voltage to MR damper.

• Earthquakes and Structures
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• 제17권2호
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• pp.131-141
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• 2019

Structural control systems have uncertainties in their structural parameters and control devices which by using reliability analysis, uncertainty can be modeled. In this paper, reliability of controlled structures equipped with semi-active Magneto-Rheological (MR) dampers is investigated. For this purpose, at first, the effect of the structural parameters and damper parameters on the reliability of the seismic responses are evaluated. Then, the reliability of MR damper force is considered for expected levels of performance. For sensitivity analysis of the parameters exist in Bouc- Wen model for predicting the damper force, the importance vector is utilized. The improved first-order reliability method (FORM), is used to reliability analysis. As a case study, an 11-story shear building equipped with 3 MR dampers is selected and numerically obtained experimental data of a 1000 kN MR damper is assumed to study the reliability of the MR damper performance for expected levels. The results show that the standard deviation of random variables affects structural reliability as an uncertainty factor. Thus, the effect of uncertainty existed in the structural model parameters on the reliability of the structure is more than the uncertainty in the damper parameters. Also, the reliability analysis of the MR damper performance show that to achieve the highest levels of nominal capacity of the damper, the probability of failure is greatly increased. Furthermore, by using sensitivity analysis, the Bouc-Wen model parameters which have great importance in predicting damper force can be identified.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1060-1065
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• 2005

An Independent Administrative Corporation Japan Agency for Marine-Earth Science and Technology (JAMSTEC) is developing light-and-small Autonomous Underwater Vehicles (AUV)$^{1)}$, named 'MR-X1' (Marine Robot Experimental 1), which can cruise, investigate and observe by itself without human's help. In this paper, we consider the motion control problem of 'MR-X1' and derive a controller. Since the dynamic property of 'MR-X1' is changed by the influence of the speed, the mathematical model of 'MR-X1' becomes the nonlinear model. In order to design a controller for 'MR-X1', we generally apply nonlinear control theories or linear control theories with some constant speed situation. If we design a controller by applying Linear Quadratic (LQ) optimal control theory, the obtained controller only compensates t e optimality at the designed speed situation, and does not compensate the stability at another speed situations. This paper proposes a controller design method using Linear Matrix Inequalities (LMIs)$^{2),3),4)}$, which can adapt the speed variation of 'MR-X1'. And examples of numerical analysis using our designed controller are shown.

• 한국전기전자재료학회논문지
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• 제25권9호
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• pp.738-742
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• 2012

This paper conducted a study on how the heat radiation of light emitting diode(LED) luminaires affects the indoor temperature increase. The effect was compared with that of a 20 W compact fluorescent lamp(CFL) and a 50 W MR16 halogen lamp which are most widely used inside of cruises, a LED downlight and a 4W MR16 LED replacing each of them. We installed a luminarie inside a thermally shielded chamber, measuring the temperature changes under the same volume every 5 minutes and compared the result with theoretically calculated heat radiation. The temperature changes in the chamber was measured four times, on seven hours' period in order to keep sufficient time once the temperature reaches the thermal equilibrium state. The results showed that the temperature of the 20 W E26 CFL and the 10 W LED downlight increased by $21.1^{\circ}C$ and $10.4^{\circ}C$ respectively, while that of the 50 W halogen MR16 and the 4 W LED MR16 increased by $33.9^{\circ}C$ and $4.8^{\circ}C$ respectively. The experimental heat radiation were calculated from the results and the experimental heat radiation of the CFL and the LED downlight were 171.5 cal and 86.5 cal, and those of the halogen MR16 and the LED MR16 were 275.3 cal and 36.5 cal. Therefore, the heat radiation was reduced by 49.5% and 86.7%, respectively, by replacing conventional light source with LED. In conclusion, we can expect a reduction of power consumption in air condition system and the effect on indoor temperature increase by application of LED luminaires.

• 한국전산구조공학회논문집
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• 제21권5호
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• pp.465-474
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• 2008

실시간 하이브리드 실험법(real-time hybrid testing method)은 구조물의 수치해석부와 실험부 부분구조를 운동방정식으로 통합하여 실시 간으로 동시에 계산과 실험을 수행하는 방법이다 본 연구는 실시간 하이브리드 실험법을 사용하여 수동 및 준능동 MR감쇠기가 설치된 건축구조물의 내진성능을 정량적으로 평가한다. 건물 모델은 실물 크기 5층 건물을 강제진동실험 결과를 통해 식별한 수치모델로 사용하였고, MR감쇠기는 실험적 부분구조르 UTM에 설치되었다. 본 연구에서 수행되는 실시간 하이브리드 실험은 사인파 및 지진파 가진을 통하여 얻은 결과와 전류에 따른 MR감쇠기의 제어력을 이용하여 얻은 Bouc-Wen모델을 사용하여 얻은 해석모델과 일치함으로 그 유효성을 입증하였다. 또한 예비연구로써 구조물의 응답을 최적으로 제어하기 위한 clipped-optimal 제어알고리즘과 modulated homogeneous friction 준능동 제어알고리즘을 MR감쇠기에 적용하였다. 각 전류별 Bouc-Wen모델을 곡선맞춤하여 각각의 Bouc-Wen모델 파라미터를 식별하였으며 그 결과를 준능동 제어알고리즘 수치해석에 적용하였다. 또한 실시간 하이브리드 실험법을 이용한 준능동 제어 실험결과와 해석결과를 비교하여 준능동 제어알고리즘의 성능을 평가함에 있어 실시간 하이브리드 실험이 합리적임을 보여준다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.241-242
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• 2013

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1351-1352
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• 2013