• International Journal of Railway
• /
• 제1권3호
• /
• pp.94-98
• /
• 2008

Static inverters are essential devices onboard of rolling stock. State-of-the-art static inverters have an impact on both rail infrastructure and vehicle maintenance due to their new topology with new features. The paper describes two important aspects as examples of new features available in state-of-the-art static inverters: active input current control and the effects on the rail infrastructure as well as the detection of the state of charge and the state of health of batteries to simplify vehicle maintenance.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2005년도 학술발표회 논문집
• /
• pp.153-160
• /
• 2005

A new nonlinear static analysis method, Effective Modal Pushover Analysis (EMPA) which can evaluate earthquake responses such as story drift and plastic rotation of plastic hinges addressing higher mode effects was developed. Unlike existing nonlinear static procedure based on properties of fundamental vibration mode, the EMPA performs nonlinear static analysis using multiple effective modes constructed by direct combination of natural vibration modes. Therefore higher mode effects can be efficiently considered. In the present study, procedures of the EPMA evaluating inelastic earthquake responese were established and the results were verified by nonlinear time history analysis. The EMPA can be applied to seismic evaluation of high-rise buildings and irregular buildings where higher mode effects become conspicuous.

• Wind and Structures
• /
• 제31권5호
• /
• pp.459-472
• /
• 2020

This study focused on the non-synoptic, tornado-like wind-induced effects on flexible horizontal structures that are extremely sensitive to winds. More specifically, the nonuniform, intensive vertical wind-velocity and transient natures of tornado events and their effects on the global behavior of a long-span bridge were investigated. In addition to the static part in the modeling of tornado-like wind-induced loads, the motion-induced effects were modeled using the semi-empirical model with a two-dimensional (2-D) indicial response function. Both nonlinear wind-induced static analysis and linear aeroelastic analysis in the time domain were conducted based on a 3-D finite-element model to investigate the bridge performance under the most unfavorable tornado pattern considering wind-structure interactions. The results from the present study highlighted the important effects due to abovementioned tornado natures (i.e., nonuniform, intensive vertical wind-velocity and transient features) on the long-span bridge, and hence may facilitate more appropriate wind design of flexible horizontal structures in the tornado-prone areas.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제51권8호
• /
• pp.413-424
• /
• 2002

Recently, in the linear motion system, high performances are required In dynamic characteristics. Vector control method is capable of instantaneous thrust control can meet these high performance requirements. Linear induction motor(LIM) have static and dynamic end effects due to its finite core length, so that per-phase impedances are asymmetric and an air gap flux distribution is distorted. These points of the d-q axis equivalent circuit model considering both end effects is more complicated. This paper proposes the d-q axis equivalent circuit and the vector control method considering both static and dynamic end effects of the LIM. As a result, it is shown that the results of the equivalent circuit method(ECM) have a good agreement with those of the finite element method(FEM).

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 제4회 영호남학술대회 논문집
• /
• pp.19-24
• /
• 2002

Static electricity is an everyday phenomenon. There can be few of us who have not experienced a static shock after sliding across a car seat. Other static nuisance effects include the cling of some fabrics to the body, the sticking of a plastic document cover, or the attraction of dust to a TV or computer screen. However, static electricity has been a serious industrial problem. The age of electronics brought with it new problems associated with static electricity and electrostatic discharge. And, as electronic devices became faster and smaller, their sensitivity to ESD increased. In this work, We are study on the control technique of electo-static discharges using semiconductor circuits. Our circuits are prevented well to electrostatic shock or damages from triboelectric charging in cars everyday life.

• The Journal of Korean Physical Therapy
• /
• 제29권3호
• /
• pp.142-144
• /
• 2017

Purpose: Few studies have addressed the effect of diurnal circadian rhythms on postural stability, and thus the aim of the present study was to examine circadian effects on static and dynamic postural stability in young adults. Methods: Twenty-four subjects (9 men, 11 women: age=$22.20{\pm}1.77$, height=$167.20{\pm}10.47$, weight=$59.85{\pm}10.66$) from a university community volunteered for this study. Static and dynamic balance testing, which recorded using a Good Balance system (Good Balance, Metitur Ltd, Finland) was conducted at 9:00, 13:00, and 17:00 hours on two consecutive days, and the sequencing of static and dynamic balance tests were randomized. Results were analyzed using the non-parametric one-way repeated Friedman test in SPSS version 18.0 (SPSS Inc., Chicago, IL, USA), and variable found to be significant were subjected to Wilcoxon post hoc testing. Results: Static and dynamic balance showed significant difference at the three times assessments (test at 9:00, 13:00, and 17:00) during circadian. In the post hoc test of static (anteroposterior distance, mediolateral distance and COP (center of pressure) velocity) and dynamic balance (performance time), 13:00 was the longer and faster than 9:00. Conclusion: These results indicated that control of postural balance is influenced by diurnal circadian rhythms, and confirm that control of postural balance is more effective and better performance in the 09:00 hours than 13:00 hours or 17:00 hours.

• Geomechanics and Engineering
• /
• 제1권1호
• /
• pp.1-15
• /
• 2009

Many aspects of the behavior of sands are affected by the content of non-plastic fine particles and these various aspects should be included in a constitutive model for the soil behavior. The fines content affects maximum and minimum void ratios, compressibility, shear strength, and static liquefaction under undrained conditions. Twenty-eight undrained triaxial compression tests were performed on mixtures of sand and fine particles with fines contents of 0, 10, 20, 30, 50, 75, and 100% to study the effects of fines on void ratio, compressibility, and the occurrence of static liquefaction. The experiments were performed at low consolidation pressures at which liquefaction may occur in near-surface, natural deposits. The presence of fines creates a particle structure in the soil that is highly compressible, enhancing the potential for liquefaction, and the fines also alter the basic stress-strain and volume change behavior, which should be modeled to predict the occurrence of static liquefaction in the field. The void ratio at which liquefaction occurs for each sand/fines mixture was determined, and the variation of compressibility with void ratio was determined for each mixture. This allowed a relation to be determined between fines content, void ratio, compressibility, and the occurrence of static liquefaction. Such relations may vary from sand to sand, but the present results are believed to indicate the trend in such relations.

• The Journal of Korean Physical Therapy
• /
• 제31권5호
• /
• pp.328-332
• /
• 2019

Purpose: This study examined the effects of transcranial direct current stimulation (tDCS) on the static balance ability of patients with back pain. Methods: The subjects comprised of 30 males and females in their 20s, who were divided into two groups with and without tDCS. The balance posture ratio score was calculated to determine the changes in balance ability before and after the application of tDCS using balance equipment. A paired t-test was conducted to determine the changes over time, and an independent t-test was performed to determine the changes between the groups. The significance level was set to ${\alpha}=0.05$. Results: A significant difference in the changes in the static balance ability of CTDCSG between before and after applying tDCS was observed while the subjects' eyes were open (p<0.05). A comparison between the groups after the experiments revealed significantly increased changes in CTDCSG compared to STDCSE (p<0.05). The changes in static balance ability were not significant when the subjects' eyes were closed (p>0.05). Conclusion: The application of tDCS positively changed the static balance ability of patients with back pain. The results of this study showed that tDCS could be used as an intervention to increase the static balance ability of patients with back pain in the clinical field. The study results could be used further as foundational data for future studies on tDCS.

• 한국생산제조학회지
• /
• 제19권6호
• /
• pp.797-803
• /
• 2010

A method has been developed to tune the static stiffness at a rotation joint considering the whole machine tool system by interactive use of finite element method and experiment. This paper describes the procedure of this method and shows the results. The method uses the static experiment on measurement model which is set-up so that the effects of uncertain factors can be excluded. For FEM simulation, the rotation joint model is simplified using only spindle, bearing and spring. At the rotation joint, the damping coefficient is ignored, The spindle and bearing is connected by only spring. By static experiment, 500 N is forced to the front and behind portion of spindle and the deformation is measured by capacitive sensor. The deformation by FEM simulation is extracted with changing the static stiffness from the initial static stiffness considering only rotation joint. The tuning static stiffness is obtained by exploring the static stiffness directly trusting the deformation from the static experiment. Finally, the general tuning method of the static stiffness of machine tool joint is proposed using the force stream and the modal analysis of machine tool.

• 대한물리의학회지
• /
• 제15권3호
• /
• pp.89-98
• /
• 2020

PURPOSE: This study investigated the effects of unilateral static stretching on the flexibility and symmetry of the lower leg, and temporal gait variables in gait asymmetry people. METHODS: Twenty gait asymmetry people were divided into a unilateral static stretching group (USG, n = 10) and control group (CON, n = 10). The USG performed unilateral static stretching for 60 minutes, three times a week, and eight weeks. The flexibility of the lower leg (SR), and symmetry (BR), and temporal gait variables (Step length; SL, gait speed; GS) were measured before, after four and eight weeks of unilateral static stretching. Moreover, SI (symmetry index; SI) was calculated from the measured SL value. Statistical analyses were conducted using one-way ANOVA and two-way ANOVA with repeated measures, a paired t-test, and multiple comparisons according to Scheffe. RESULTS: SR and BR in the dominant and non-dominant side, and GS were increased significantly at USG after eight-weeks compared to before unilateral static stretching (p < .05). The difference in BR in the dominant and non-dominant side, and step length (SI) decreased significantly at USG after eight-weeks compared to before unilateral static stretching (p < .05). CONCLUSION: Unilateral static stretching improves the flexibility and symmetry of the lower leg, and temporal gait variables in gait asymmetry people.