• Structural Engineering and Mechanics
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• 제69권3호
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• pp.347-359
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• 2019

This paper aims to evaluate the behavior of Dorim-Goh bridge in Seoul, Korea, under static and dynamic loads effects by ambient trucks. The prestressed concrete (PSC) girders and reinforcement concrete (RC) slab of the bridge are evaluated and assessed. A short period monitoring system is designed which comprises displacement, strain and accelerometer sensors to measure the bridge performance under static and dynamic trucks loads. The statistical analysis is used to assess the static behavior of the bridge and the wavelet analysis and probabilistic using Weibull distribution are used to evaluate the frequency and reliability of the dynamic behavior of the bridge. The results show that the bridge is safe under static and dynamic loading cases. In the static evaluation, the measured neutral axis position of the girders is deviated within 5% from its theoretical position. The dynamic amplification factor of the bridge girder and slab are lower than the design value of that factor. The Weibull shape parameters are decreased, it which means that the bridge performance decreases under dynamic loads effect. The bridge girder and slab's frequencies are higher than the design values and constant under different truck speeds.

• Geomechanics and Engineering
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• 제29권1호
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• pp.65-77
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• 2022

Determination of strength properties of intact rock using artificial cores has been considered in recent years. In this study, some relationships for estimating the static properties of dolomudstone cores of the Asmari reservoir were presented using artificial cores prepared from cuttings of two wells, southwest of Iran. For this purpose, first natural cuttings (NC) and 33 cores including dolomite limestone (dolomudstone), anhydrite and anhydrite dolomite were prepared between depths of 1714 and 2208 meters. Petrographic, physical, mechanical and dynamic tests were performed on cores, NC and artificial cuttings (AC) which was prepared from the residuals of dolomudstone cores. For preparing the artificial cores, the average porosity of the dolomudstone cores was considered and determined using four methods. Artificial and natural cuttings were classified as dolomite limestone and dolomite limestone to calcareous dolomite, respectively. Using ordinary Portland cement (OPC), water, AC and NC artificial cores were prepared. Results of evaluating the proposed relationships using statistical criteria showed that the static properties of the artificial cores can be used to predict the static properties of the dolomudstone cores.

• Steel and Composite Structures
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• 제48권4호
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• pp.419-428
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• 2023

In this paper, dynamic and static bending of ball modelled by nanocomposite microbeam by nanoparticles seeing agglomeration is presented. The structural damping is considered by Kelvin-Voigt model. The agglomeration effects are assumed using Mori-Tanaka model. The football ball is modeled by third order shear deformation theory (TSDT). The motion equations are derived by principle of Hamilton's and energy method assuming size effects on the basis of Eringen theory. Using differential quadrature method (DQM) and Newmark method, the static and dynamic deflections of the structure are obtained. The effects of agglomeration and CNTs volume percent, damping of structure, nonlocal parameter, length and thickness of micro-beam are presented on the static and dynamic deflections of the nanocomposite structure. Results show that with increasing CNTs volume percent, the maximum dimensionless dynamic deflection is reduced about 17%. In addition, assuming CNTs agglomeration increases the dimensionless dynamic deflection about 14%. It is also found that with increasing the CNTs volume percent from 0 to 0.15, the static deflection is decreased about 3 times due to the enhance in the stiffness of the structure. In addition, with enhancing the nonlocal parameters, the dynamic deflection is increased about 3.1 times.

• Journal of Energy Engineering
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• 제23권3호
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• pp.231-234
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• 2014

The crankshaft is a complex component, and as such, the influence of its geometric parameters on stresses seen under service loads is not well understood. The objectives of this work is to investigate the effects of a wide range of geometric parameters on stresses in crankshafts, to find correlation between results and to formulate simple methods of predicting peak stress levels: It is intended to achieve this by use of fatigue method. Analyses are carried out in 2D and 3D, making use of symmetry as far as possible. Variations in stresses are plotted over a wide range for each of the parameters. The analysis methods give accurate results for stress analysis of crankshafts and offer several advantages over traditional experimental techniques; they are ideally suited to parametric analyses, can be carried out relatively quickly, results are repeatable because boundary conditions can be exactly defined, and the cost of analysis is significantly reduced.The analysis is carried out in ANSYS for crankshaft along for single cylinder camless engine.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1357-1368
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• 2017

The lack of controllability over the wind causes fluctuations in the output power of the wind generators (WGs) located at the wind farms. Distribution Static Compensator (DSTATCOM) equipped with Battery Energy Storage System (BESS) can significantly smooth these fluctuations by injecting or absorbing appropriate amount of active power, thus, controlling the power flow of WGs. But because of the component aging and thermal drift, its harmonic filter parameters vary, resulting in performance degradation. In this paper, Quantitative Feedback Theory (QFT) is used as a robust control scheme in order to deactivate the effects of filter parameters variations on the wind power generation power smoothing performance. The proposed robust control strategy of the DSTATCOM is successfully applied to a microgrid, including WGs. The simulation results obviously show that the proposed control technique can effectively smooth the fluctuations in the wind turbines' (WT) output power caused by wind speed variations; taking into account the filter parameters variations (structural parameter uncertainties).

• Journal of the Institute of Electronics Engineers of Korea SD
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• 제49권4호
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• pp.1-6
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• 2012

This paper presents the extraction and analysis of small-signal parameters of tunneling field-effect transistors (TFETs) by using TCAD device simulation. The channel lengths ($L_G$) of the simulated devices varies from 50 nm to 100 nm. The parameter extraction for TFETs have been performed by quasi-static small-signal model of conventional MOSFETs. The small-signal parameters of TFETs with different channel lengths were extracted according to gate bias voltage. The $L_G$-dependency of the effective gate resistance, transconductance, source-drain conductance, and gate capacitance are different with those of conventional MOSFET. The $f_T$ of TFETs is inverely proportional not to $L_G{^2}$ but to $L_G$.

• Advances in aircraft and spacecraft science
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• 제9권2호
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• pp.119-130
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• 2022

Supersonic projectiles like rockets, missiles, or aircraft find various applications in the field of defense. The shape of the wings is mainly designed as wedge shape or delta wings for supersonic vehicles. The study of supersonic flows over the wedges and flat plate delta wings around the large scale of incidence angle is considered in the supersonic projectile. In the present paper, the prime attention is to study the pressure at the nose of the plane wedge over the various Mach number and the various angles of incidence. Ghosh piston theory is used to obtain the pressure distribution analytically, and the results are compared with CFD analysis results. The wedge angle and Mach number are the parameters considered for the research work. The range of wedge angle is 50 to 250, and Mach number is 1.5 to 4.0 are considered for the current research work. The analytical results show excellent agreement with the CFD results. The results show that both the parameters wedge angle and Mach number are influential parameters to vary the static pressure. The static pressure increases with an increase in Mach number and wedge angle.

• Journal of the Institute of Electronics Engineers of Korea SD
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• 제49권5호
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• pp.30-36
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• 2012

A new BIST(Built-In Self-Test) scheme to test ADC(Analog-to-Digital Converter) with a transition detector is proposed. The proposed BIST is able to replaces histogram method, the most popular approach in static testing of ADC. With a ramp signal as an input test stimulus, the proposed BIST calculates ADC's static parameters such as offset, gain, INL(Integral Non-Linearity) and DNL(Differential Non-Linearity). The three detectors in the proposed BIST can deal with a transient zone problem, a phenomenon due to random noise in real test environments and are cost efficient at various acceptable ranges determined as a test spec. The simulation results validate that our method performs accurate static test and show the reduction of the hardware overhead.

• Physical Therapy Korea
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• 제28권3호
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• pp.200-207
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• 2021

Background: Postural control deficit is a major characteristic in patients with chronic ankle instability (CAI). Elastic ankle tapings are commonly used to facilitate postural control in patients with CAI as well as prevent relapse of a lateral ankle sprain. However, equivocal evidence exists concerning the effect of elastic ankle taping on postural control. Objects: This study aimed to evaluate the effects of elastic ankle tapings using kinesio taping (KT) and dynamic taping (DT) on static and dynamic postural control in patients with CAI. Methods: Fifteen subjects with CAI were participated in this study. The participants performed tests under three conditions (barefoot, KT, and DT). Static postural control was evaluated using the one-leg standing test (OLST) and dynamic postural control using the modified Star Excursion Balance Test (mSEBT). One-way repeated-measures analysis of variance was used to compare center of pressure (CoP) data and normalized mSEBT reach distances among the three conditions (with α = 0.05). Results: The CoP parameters (path length, ellipse area, and mean velocity) of the OLST significantly decreased on applying KT and DT compared with those when barefoot. The normalized reach distances in the anteromedial (AM), medial (M), and posteromedial (PM) directions of the mSEBT significantly increased with DT compared to that in the control condition. Further, the higher reach distances with KT compared with those in the control condition were obtained in the M and PM directions of the mSEBT. No significant differences were identified in any of the OLST and SEBT parameters between the two different taping applications. Conclusion: KT and DT improved static postural control during the OLST compared with the control condition. Moreover, these tapes improved dynamic postural control during the mSEBT compared to the control. Therefore, elastic ankle tapings are useful prophylactic devices for the prevention and treatment of ankle sprain in people with CAI.

• Journal of Korea Entertainment Industry Association
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• 제14권6호
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• pp.221-230
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• 2020

The purpose of this study was to investigate the effect of resistance exercise with vibration stimulation methods on static balance and gait parameters in experienced back pain adults. This study was Three group pretest-posttest design. A total of 30 experienced back pain adults voluntarily participated in the study. Subjects were randomly assigned to the resistance exercise with 8 Hz vibration stimulation(n=10), resistance exercise with 30 Hz vibration stimulation(n=10), and lumbar stabilization exercise groups(n=10). The static balance and the gait parameters, as such stance phase, swing phase, stride length and cadence, were measured using balance measuring equipment and gait analysis treadmill at before and after 6 week. Intervention of each group were performed, three times a week for 6 weeks, and 30 minutes a day. The effect of intervention on static balance, stance phase, swing phase, stride length and cadence were significantly differences after 6 weeks in each group(p<.05). In the comparison of the effects between the groups, static balance and stance phase were significantly difference after 6 weeks(p<.05), but in the swing phase, stride length and cadence, there were no significant differences. As a result, it is considered that resistance exercise with vibration stimulation improved leg muscle strength by a mechanism causing muscle contraction, and the strengthened leg muscle enhanced had a positive effect on balance ability. And improved balance ability was considered a more positive effect on walking ability by allowing the body to stably control posture while moving.