• Wind and Structures
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• v.30 no.4
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• pp.379-392
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• 2020

The paper presents a Life-Cycle Cost-based optimization framework for wind-excited tall buildings equipped with Tuned Mass Dampers (TMDs). The objective is to minimize the Life-Cycle Cost that comprises initial costs of the structure, the control system and costs related to repair, maintenance and downtime over the building's lifetime. The integrated optimization of structural sections and mass ratio of the TMDs is carried out, leading to a set of Pareto optimal solutions. The main advantage of the proposed methodology is that, differently from the traditional optimal design approach, it allows to perform the unified design of both the structure and the control system in a Life Cycle Cost Analysis framework. The procedure quantifies wind-induced losses, related to structural and nonstructural damage, considering the stochastic nature of the loads (wind velocity and direction), the specificity of the structural modeling (e.g., non-shear-type vibration modes and torsional effects) and the presence of the TMDs. Both serviceability and ultimate limit states related to the structure and the TMDs' damage are adopted for the computation of repair costs. The application to a case study tall building allows to demonstrate the efficiency of the procedure for the integrated design of the structure and the control system.

• Journal of Oral Medicine and Pain
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• v.48 no.3
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• pp.75-80
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• 2023

Temporomandibular disorders (TMDs) are a group of musculoskeletal disorders that encompass symptoms caused by abnormalities of the craniofacial structures of the temporomandibular joint (TMJ), muscles involved in the masticatory system, and other related tissues or structures. Although TMDs can occur at any age, research on the prevalence, epidemiology, and treatment strategies of TMDs has been conducted in all age groups, but primarily in adults. Unlike adults, children and adolescents are in a period of cognitive and physical development. Because of this growth potential, children respond better to TMD treatment than adults do. However, clinicians must remember that chronic pain and growth abnormalities can occur if the patient's symptoms and signs are not accurately diagnosed and treated. This article reviews the growth and development of the craniofacial region, including the TMJ, and discusses considerations when diagnosing and treating TMDs in children and adolescents.

• Imaging Science in Dentistry
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• v.45 no.1
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• pp.1-5
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• 2015

Purpose: Lateral pterygoid muscle (LPM) plays an important role in jaw movement and has been implicated in Temporomandibular disorders (TMDs). Migraine has been described as a common symptom in patients with TMDs and may be related to muscle hyperactivity. This study aimed to compare LPM volume in individuals with and without migraine, using segmentation of the LPM in magnetic resonance (MR) imaging of the TMJ. Materials and Methods: Twenty patients with migraine and 20 volunteers without migraine underwent a clinical examination of the TMJ, according to the Research Diagnostic Criteria for TMDs. MR imaging was performed and the LPM was segmented using the ITK-SNAP 1.4.1 software, which calculates the volume of each segmented structure in voxels per cubic millimeter. The chi-squared test and the Fisher's exact test were used to relate the TMD variables obtained from the MR images and clinical examinations to the presence of migraine. Logistic binary regression was used to determine the importance of each factor for predicting the presence of a migraine headache. Results: Patients with TMDs and migraine tended to have hypertrophy of the LPM (58.7%). In addition, abnormal mandibular movements (61.2%) and disc displacement (70.0%) were found to be the most common signs in patients with TMDs and migraine. Conclusion: In patients with TMDs and simultaneous migraine, the LPM tends to be hypertrophic. LPM segmentation on MR imaging may be an alternative method to study this muscle in such patients because the hypertrophic LPM is not always palpable.

• Earthquakes and Structures
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• v.9 no.1
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• pp.73-91
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• 2015

The effectiveness of tuned mass dampers (TMDs) in reducing the seismic response of civil structures is still a debated issue. The few studies regarding TMDs on inelastic structures indicate that they would perform well under moderate earthquake loading, when the structure remains linear or weakly nonlinear, while tending to fail under severe ground shaking, when the structure experiences strong nonlinearities. TMD seismic efficiency should be therefore rationally assessed by considering to which extent moderate and severe earthquakes respectively contribute to the expected cost of damages and losses over the lifespan of the structure. In this paper, a method for evaluating, in a life-cycle cost (LCC) perspective, the seismic effectiveness of TMDs on inelastic building structures is presented and exemplified on the SAC LA 9-storey steel moment-resisting frame benchmark building. Results show that the LCC concept may provide an appropriate alternative to traditional performance criteria for the evaluation of the effectiveness of TMDs and that TMD installation on typical existing middle-rise buildings in high seismic hazard regions may significantly reduce building lifetime cost despite the poor control performance observed under the most severe seismic events.

• Wind and Structures
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• v.14 no.2
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• pp.113-131
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• 2011

Excessive wind-induced motion in tall buildings can cause discomfort, affect health, and disrupt the daily activities of the occupants of a building. Dynamic vibration absorbers such as the tuned mass dampers (TMDs) can be used to reduce the wind-induced motion below a specified tolerable serviceability limit state (SLS) criterion. This study investigates whether the same probability of not exceeding specified wind-induced motion levels can be achieved by torsionally sensitive structures without/with linear/nonlinear TMDs subjected to partially correlated wind forces, if they are designed to just meet the same SLS criterion. For the analyses, different structures and the uncertainty in the response, wind load and perception of motion is considered. Numerical results indicate that for structures that are designed or retrofitted without or with optimum linear TMDs and satisfying the same SLS criterion, their probability of exceeding the considered criterion is very consistent, if the inherent correlation between the wind forces is considered in design. However, this consistency deteriorates if nonlinear TMDs are employed. Furthermore, if the correlation is ignored in the design, in many cases a slightly unconservative design, as compared to the designed by considering correlation, is achieved.

• Smart Structures and Systems
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• v.18 no.4
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• pp.683-705
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• 2016

A semi-active algorithm for edgewise vibration control of the spar-type floating offshore wind turbine (SFOWT) blades, nacelle and spar platform is developed in this paper. A tuned mass damper (TMD) is placed in each blade, in the nacelle and on the spar to control the vibrations for these components. A Short Time Fourier Transform algorithm is used for semi-active control of the TMDs. The mathematical formulation of the integrated SFOWT-TMDs system is derived by using Euler-Lagrangian equations. The theoretical model derived is a time-varying system considering the aerodynamic properties of the blade, variable mass and stiffness per unit length, gravity, the interactions among the blades, nacelle, spar, mooring system and the TMDs, the hydrodynamic effects, the restoring moment and the buoyancy force. The aerodynamic loads on the nacelle and the spar due to their coupling with the blades are also considered. The effectiveness of the semi-active TMDs is investigated in the numerical examples where the mooring cable tension, rotor speed and the blade stiffness are varying over time. Except for excessively large strokes of the nacelle TMD, the semi-active algorithm is considerably more effective than the passive one in all cases and its effectiveness is restricted by the low-frequency nature of the nacelle and the spar responses.

• Wind and Structures
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• v.2 no.3
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• pp.151-171
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• 1999

In its 90 years of life, the Tuned Mass Damper have found application in many fields of engineering as a vibration reducing device. The evolution of the theory of TMDs is briefly outlined in the paper. A generalised mathematical linear model for the analysis of the response of line-like structures with TMDs is presented. The system matrices of the system including the TMDs are written in the state space as a function of the mean wind speed. The stability of the system can be analysed and the Power Spectral Density Function of any response parameter calculated, taking into account an arbitrary number of modes of vibration as well as an arbitrary number of TMDs, for any given PSDF of the excitation. The procedure can be used to optimise the number, position and mechanical properties of the damping devices, with respect to any response parameter. Due to the stationarity of the excitation, the method is well suited to structures subjected to the wind action. In particular the procedure allows the calculation of the onset galloping wind speed and the response to buffeting, and a linearisation of the aeroelastic behaviour allows its use also for the evaluation of the response to vortex shedding. Finally three examples illustrate the suggested procedure.

• Coupled systems mechanics
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• v.6 no.3
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• pp.229-249
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• 2017

A new technique to mitigate irregular buildings with soil structure interaction (SSI) effect subjected to critical seismic waves is presented. The L-shape in plan irregular building for various reasons was selected, subjected to seismic a load which is a big problem for structural design especially without separation gap. The L-shape in plan building with different dimensions was chosen to study, with different rectangularity ratios and various soil kinds, to show the effect of the irregular building on the seismic response. A 3D building subjected to critical earthquake was analyzed by structural analysis program (SAP2000) fixed and with SSI (three types of soils were analyzed, soft, medium and hard soils) to find their effect on top displacement, base shear, and base torsion. The straining actions were appointed and the treatment of the effect of irregular shape under critical earthquake was made by using tuned mass damper (TMD) with different configurations with SSI and without. The study improve the success of using TMDs to mitigate the effect of critical earthquake on irregular building for both cases of study as fixed base and raft foundation (SSI) with different TMDs parameters and configurations. Torsion occurs when the L-shape in plan building subjected to earthquake which may be caused harmful damage. TMDs parameters which give the most effective efficiency in the earthquake duration must be defined, that will mitigate these effects. The parameters of TMDs were studied with structure for different rectangularity ratios and soil types, with different TMD configurations. Nonlinear time history analysis is carried out by SAP2000 with El Centro earthquake wave. The numerical results of the parametric study help in understanding the seismic behavior of L-shape in plan building with TMDs mitigation system.

• Journal of Oral Medicine and Pain
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• v.43 no.4
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• pp.125-130
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• 2018

Purpose: The etiology of temporomandibular disorders (TMDs) is complex and multifactorial including trauma, anatomical, pathophysiological, social and psychological factors. Psychological factors can induce or sustain TMDs in various ways. And psychological problems, such as anxiety and depression can be occurred due to TMDs. Therefore, evaluation of psychological factors in patients with TMDs is important. Although disc displacement (DD) is crucial in clinical situation, most of studies have focused on the relationship of psychosocial factors and myofascial pain. And also, Subtypes of DD can cause different degrees of discomfort, it is necessary to evaluate the psychological states of the patients according to the subtype. The Hospital Anxiety Depression Scale (HADS) is one of the self-report questionnaire to evaluate the psychological factors. HADS-Anxiety (HADS-A) and HADS-Depression (HADS-D) are assessed through 14 questions. The purpose of this study was to evaluate anxiety and depression assessed by HADS in patients diagnosed with subtypes of DD according to diagnostic criteria for TMDs. Methods: Four hundred thirty nine patients were diagnosed as one of the subtypes of DD. One hundred fourty nine subjects with no symptoms were set as control groups. All of them answered the HADS for Koreans. The cut-off score for anxiety and depression was set a score of 8. The chi-square test was performed to evaluate association between DD and anxiety/depression. Results: There was a significant difference in HADS-D between five groups (p<0.01). However, there was no significant difference in HADS-A. All the DD groups showed a significant difference in HADS-D compared with the control group except the DD without reduction without limited opening group. The DD without reduction with limited opening group showed the highest rates in HADS-D (40.4%). Conclusions: Based on the above results, it is necessary to consider the depression in treatment of the patients with DDs.

• Journal of the korean academy of Pediatric Dentistry
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• v.51 no.2
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• pp.185-196
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• 2024

Temporomandibular joint disorders (TMDs) can occur at any age, including childhood and adolescence, and pain-related TMDs can affect growth and quality of life. In the present study, recent trends in the diagnosis and treatment of TMDs in children and adolescents were analyzed over a 10-year period. Using 10 years of data from the Health Insurance Review and Assessment Service (HIRA) and Jeonbuk National University (JBNU) Dental Hospital, patients between 0 and 19 years of age diagnosed with K07.6 (temporomandibular joint disorders) were analyzed by 5-year bins. Both datasets indicated a higher prevalence in females (1.2-fold in HIRA, 1.5-fold in JBNU) and in ages 15 to 19 years (72.1% in HIRA, 74.7% in JBNU). HIRA reported a 42.3% increase in prevalence per 100,000 people, from 651.4 in 2011 to 927.0 in 2020. JBNU reported K07.66 (masticatory muscle disorders) as the most common diagnosis in subjects under 10 years of age and K07.60 (internal derangement of temporomandibular joint) in those over 10 years of age. In addition, both were treated mainly by a combination of physical therapy and medication, and the treatment rate increased in accordance with age. Because TMDs can affect various structures in the orofacial region and cause pain that tends to differ with age, an early and specific diagnosis appropriate for age is important for treatment. Therefore, pediatric dentists need to promptly recognize TMDs in children and adolescents and consult with specialists as the prevalence increases.