• Smart Structures and Systems
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• 제19권6호
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• pp.665-678
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• 2017

In this paper the tuned mass-damper-inerter (TMDI) is considered for passive vibration control and energy harvesting in harmonically excited structures. The TMDI couples the classical tuned mass-damper (TMD) with a grounded inerter: a two-terminal linear device resisting the relative acceleration of its terminals by a constant of proportionality termed inertance. In this manner, the TMD is endowed with additional inertia, beyond the one offered by the attached mass, without any substantial increase to the overall weight. Closed-form analytical expressions for optimal TMDI parameters, stiffness and damping, given attached mass and inertance are derived by application of Den Hartog's tuning approach to suppress the response amplitude of force and base-acceleration excited single-degree-of-freedom structures. It is analytically shown that the TMDI is more effective from a same mass/weight TMD to suppress vibrations close to the natural frequency of the uncontrolled structure, while it is more robust to detuning effects. Moreover, it is shown that the mass amplification effect of the inerter achieves significant weight reduction for a target/predefined level of vibration suppression in a performance-based oriented design approach compared to the classical TMD. Lastly, the potential of using the TMDI for energy harvesting is explored by substituting the dissipative damper with an electromagnetic motor and assuming that the inertance can vary through the use of a flywheel-based inerter device. It is analytically shown that by reducing the inertance, treated as a mass/inertia-related design parameter not considered in conventional TMD-based energy harvesters, the available power for electric generation increases for fixed attached mass/weight, electromechanical damping, and stiffness properties.

• 한국공간구조학회논문집
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• 제6권3호
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• pp.59-67
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• 2006

수동동조질량감쇠기의 진동제어 효과는 질량감쇠기와 구조물과의 동조로 인하여 나타나고 있다. 그러나 바닥판 구조물의 질량과 강성의 변화로 인하여 실제 구조물에 있어서 비동조 현상이 일어나기도 한다. 이러한 상황에서는 수동동조질량감쇠기의 성능이 비효율적이며 경우에 따라서는 구조물의 진동을 증가시키기도 한다. 본 논문에서는 기계나 사람에 의한 바닥판 구조물의 진동을 줄이기 위하여 자기유체감쇠기의 적용성을 알아보고자 한다. 준 능동제어와 groundhook 제어 알고리즘을 적용하여 준능동감쇠기의 성능과 수동질량감쇠기의 성능을 비교 분석하였다. 또한 비동조 상황에서의 준능동감쇠가와 수동질량감쇠기의 견인성을 비교 분석하여 다음과 같은 결론을 얻었다. 자기유체감쇠기는 동조상황에서 우수한 제어 성능을 가지고 있으며 비동조 상황에서도 우수한 견인성을 보여주고 있다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.424-431
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• 2006

Many types of tuned mass dampers (TMDs), such as active TMDs, multiple TMDs, hybrid TMDs etc., have been studied to effectively reduce the dynamic responses of a structure subjected to various types of dynamic loads. In this study, we replace a passive damper by a semi-active tuned mass damper to improve the control performance of conventional TMDs (STMD). An idealized variable damping device is used as semi-active dampers. These semi-active dampers can change the properties of TMDs in real time based on the dynamic responses of a structure. The control performance of STMD is investigated with respect to various types of excitation by numerical simulation. Groundhook control algorithm is used to appropriately modulate the damping force of semi-active dampers. The control effectiveness between STMD and a conventional passive TMD, both under harmonic and random excitations, is evaluated and compared for a single-degree-of-freedom (SDOF) structure. Excitations are applied to the structure as a dynamic force and ground motion, respectively. The numerical studies showed that the control effectiveness of STMD is significantly superior to that of the passive TMD, regardless of the type of excitations.

• Journal of Oral Medicine and Pain
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• 제25권2호
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• pp.241-245
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• 2000

In this case report, I discussed the diagnosis and treatment of two pregnant women with temporomandibular disorders(TMD) who visited the Department of Oral Medicine, PNUH. Also, I reviewed some investigations of diagnosis and treatment of TMD in pregnant women. The obtained results were as follows; 1. No single X-ray diagnostic procedure for TMD results in radiation dose that threatens the well-being of the developing embryo and fetus. 2. Most non-steroidal anti-inflammatory drugs(NSAIDs) have commonly used because these drugs are considered to be nonteratogenic, but these agents are not recommended for routine use after 3rd trimester. 3. Electro-acupuncture stimulation therapy(EAST) is contraindicated for 1st trimester, and ultrasonic deep heat therapy, microwave deep heat therapy, low level laser therapy, myo-monitor are not contraindicated for pregnant women but clinician must consider some risk of adverse fetal effects. 4. The occlusal stabilization splint may be used for pregnant women, if it is fabricated indirectly. 5. Surgical treatment is contraindicated for pregnant women.

• Physical Therapy Rehabilitation Science
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• 제9권4호
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• pp.244-251
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• 2020

Objective: Physical therapy techniques are required for patients with temporomandibular joint disorder (TMD), but the effects of treatment have not been compared. Therefore, effects of transcutaneous electrical nerve stimulation (TENS) and low level laser (LLL), which are most commonly used interventions, were compared. Design: Randomized controlled trial. Methods: Thirty-six participants with pain in the temporomandibular joint were enrolled, and 12 participants were randomly assigned to either the TENS group, LLL group, or placebo group. Each intervention was performed for a total of 6 sessions for 2 weeks. For the evaluation of the participants, the mouth opening (MO), pressure pain threshold (PPT), and stress were measured at three time periods: baseline, post-test, and follow-up at 2 weeks. Results: Significant interaction between groups according to each evaluation point was found only in PPT-masseter (p<0.05). The evaluation time point at which a significant difference appeared was at the post-test and follow-up at 2 weeks time periods. As a result of the post-test, the LLL group showed a significant improvement compared to the TENS group (p<0.05), and at 2 weeks follow-up, the TENS group showed a significant improvement compared to the placebo group (p<0.05). Conclusions: In this study, an experiment was conducted to compare the treatment effects when TENS, LLL, and placebo were given to patients with TMD. In addition, by quantitatively presenting the effect size of each treatment, this study suggests clinical use of TENS and LLL treatment for TMD.

• Journal of Oral Medicine and Pain
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• 제20권2호
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• pp.257-267
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• 1995

An Epidemiologic study was carried out on 77 TMD patients with degenerative joint disease who had visited the Orofacial Pain Clinic in Pusan National University Hospital. Al subjects were interviewed and examined clinically and radiologically using a standardized examination form. As related to gender and duration, subjective and objective sysmptoms in DJD patients were studied. The obtained results were as follows : 1. There were much more patients in the twenties or thirties, women and histories such as chronic duration and microtrauma. 2. Most patients responded positively more often to the questions of jaw function, unilateral chewing in habits, poot appetite and depression in behavioral response and shoulder pain in worsening prognosis 3. While the most common reasons for treatment were pain, noise, and limitation of opening, the associated symptoms such as headache, neckache, earache, jaw dysfunction, neck dysfunction, acute bite change and dizziness, ringing or fullness in the ears as secondary CNS excitatory effects were complained. 4. Opening the mouth in 25 to 40mm, soft end feel and deflective incisal pathway were seen and more tenderness to lateral or dorsal capsule of joint than intra or extra oral muscles were complained. 5. While there appeared no click, crepitus and single click in acute group, in chronic group, crepitus, single click and no click appeared in order of sequence. 6. Tomogram or bone scan revealed more bony changes than panorama and transcranial view.

• 한국공간구조학회논문집
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• 제17권4호
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• pp.51-58
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• 2017

The characteristics and effectiveness of double tuned mass dampers (DTMD) have been studied by many researchers. DTMD usually consists of one larger mass block and one smaller mass block. In this study, DTMD was proposed to reduce the vibration of vertical pumps in industrial plants. In order to assess the efficiency of the proposed method, numerical analysis for the simplified vertical pump model with single and double TMDs was carried out. It was also investigated that the effects of optimal TMD parameters such as frequency ratio and damping ratio on dynamic responses of the main structure. According to analysis results, DTMD are more effective to control the vibration of the vertical pump and show good robustness to the change in the stiffness of TMD.

• Structural Engineering and Mechanics
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• 제61권4호
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• pp.453-461
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• 2017

This paper presents the series multiple tuned mass dampers (STMDs) to suppress the resonant vibrations of railway bridges under the passage of high-speed trains (HSTs). A STMD device consisting of two spring-mass-damper units connected each other in series is installed on the bridge. In solution, bridge is modeled as a simply-supported Euler-Bernoulli beam with constant cross-section, and vehicle is simulated as a series of moving forces with constant speed. By the assumed mode method, the governing equations of motion of the beam-TMD device coupled system traversed by a moving train are obtained. The optimum values for the parameters of the STMD device are obtained for the criterion based on the minimization of the maximum dynamic displacement of the beam at its midspan. Single TMD and multiple TMDs in parallel are also considered for demonstration of the STMD device's performance. The results show that STMDs are effective in bridge vibration suppression and robust to parameters' change in the main system and the absorber itself.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1992년도 봄 학술발표회 논문집
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• pp.26-29
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• 1992

Modern tall buildings are subject to wind induced oscillations. Those oscillations can cause discomfort to the occupants. To control these motions, tuned mass dampers have been used. In this paper, component node synthesis, based on Lagrange multipliers formulation. is applied to the along-wind motion of tall buildings with multiple tuned mass dampers. Spectral densities of accelerations of top floor are compared by changing the numbers and locations of tuned mass dampers. It is found that multiple tuned mass dampers can be more effective than single tuned mass damper in reducing the acceleration response.

• 한국공간구조학회논문집
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• 제15권2호
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• pp.105-112
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• 2015

A shared tuned mass damper (STMD) was proposed in previous research for reduction of dynamic responses of the adjacent buildings subjected to earthquake loads. A single STMD can provide similar control performance in comparison with two traditional TMDs. In previous research, a passive damper was used to connect the STMD with adjacent buildings. In this study, a smart magnetorheological (MR) damper was used instead of a passive damper to compose an adaptive smart STMD (ASTMD). Control performance of the ASTMD was investigated by numerical analyses. For this purpose, two 8-story buildings were used as example structures. Multi-input multi-output (MIMO) fuzzy logic controller (FLC) was used to control the command voltages sent to two MR dampers. The MIMO FLC was optimized by a multi-objective genetic algorithm. Numerical analyses showed that the ASTMD can effectively control dynamic responses of adjacent buildings subjected to earthquake excitations in comparison with a passive STMD.