• Tunnel and Underground Space
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• v.14 no.6 s.53
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• pp.411-422
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• 2004

Sinkhole subsidence occurs over abandoned mine workings and can be detrimental to human lives, damage to properties and other surface structures. In this study, simulation of sinkhole development process is performed using special finite element procedure. Especially, creation of mine voids due to roof falls and generation of goaf from broken rocks are simulated using active-passive-active finite elements. An active or solid element can be made passive or void once the tensile failure criterion is satisfied in the specified sinkhole formation zone. Upon completion of sinkhole development process, these passive elements in again be made active to simulate goal region. Several finite element models are analyzed to evaluate the relationships between sinkhole formation with width of gallery. depth of mine, roof condition and bulking factor of roof rocks. This study demonstrates that the concept of passive elements in numerical analysis can be used effectively for analyzing sinkhole formation or roof fall phenomenon in general.

• Smart Structures and Systems
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• v.15 no.3
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• pp.831-846
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• 2015

Magneto-Rheological (MR) dampers are being used increasingly because of their adaptability to control algorithms and reliability of passive systems. In this paper, an extensive investigation on performance of MR dampers in semi-active and passive modes has been carried out. It is observed that the overall energy dissipation by MR dampers in passive-on modes is higher than that in semi-active modes for most of the competitive semi-active controllers. Based on the energy dissipation pattern, a novel semi-active controller, termed as "Simple Passive Semi-Active Controller", has been proposed for MR dampers. This controller can be emulated by a simple passive hardware proposed in this paper. The proposed concept of controller "hardware emulation" is innovative and can also be implemented for other semi-active devices for control algorithms of certain form. The effectiveness and reliability of the proposed controller has been investigated extensively through numerical simulations. It has been demonstrated that the proposed controller is competitive to or more effective than other widely used / investigated semi-active controllers.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.5
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• pp.517-524
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• 2015

In this paper, we propose a new target tracking filter architecture using active and passive sensors in underwater environment. A passive sensor for target tracking needs a bearing measurement of target. And target tracking filter for using passive sensor has the observability problem. On the other hand, an active sensor does not have the problem associated with system observability problem because an active sensor uses bearing and range measurement. In this paper, the tracking filter algorithm that could be used in the active and passive sensor system is proposed to analyze maneuvering target and to improve target tracking performance. The proposed tracking filter algorithm is tested by a series of computer simulation runs and the results are analyzed and compared with existing algorithm.

• Structural Engineering and Mechanics
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• v.30 no.1
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• pp.1-20
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• 2008

The dynamic characteristics of the passive, semi-active, and active tuned-liquidcolumn dampers (or TLCDs) are studied in this paper. The design of the latter two are based on the first one. A water-head difference (or simply named as water head in this paper) of a passive TLCD is pre-set to form the so-called semi-active one in this paper. The pre-set of water head is released at a proper time instant during an earthquake excitation in order to enhance the vibration reduction of a structure. Two propellers are installed along a shaft inside and at the center of a passive TLCD to form an active one. These two propellers are driven by a servo-motor controlled by a computer to provide the control force. The seismic responses of a five-story shear building with a passive, semiactive, and active TLCDs are computed for demonstration and discussion. The responses of this building with a tuned mass damper (or TMD) are also included for comparison. The small-scale shaking-table experiments of a pendulum-like system with a passive or active TLCD to harmonic and seismic excitations are conducted for verification.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.286-286
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• 2009

A small PEM fuel cell has two different stack configurations such as active and passive stacks. The active stack has a distintion of high power density although it makes system complex by using alr blower and related BOPs resulting in large system volume. On the contrary, passive stack has an advantage of compact system because it doesn't need air supplying devices although it reveals relatively low stack power density. In this study we fabricated two 10W PEMFC stacks with different stack configurations, active and passive stacks, and tested their performance and stability. The active stack consists of 13cells with an active area of $5cm^2$. The passive stack has 12cells with an active area of $16cm^2$. When we compared the stack performance of those stacks, the active stack showed higher power density compared to the passive stack, particularly at high voltage regions. However, at low voltage and high current regions, the passive stack performance was comparable to the active stack. The stack stability was largely dependent on the fuel humidity, particularly for active stack. At low humidity conditions, the active stack performance was decreased continuously and the cell voltage distribution was not uniform showing seriously low cell voltage at center cells mainly due to the cell drying. The passive stack showed relatively stable behavior at low humidity and the stack performance was largely dependent on the atmospheric conditions.

• Korean Journal of Child Studies
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• v.28 no.6
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• pp.233-247
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• 2007

The relation of children's stress-coping styles to Risk of Internet Gaming Addiction(RIGA) was examined in 662 4th, 5th and 6th grade subjects. Results showed that active coping styles were negatively but aggressive and passive/avoidant coping styles were positively related to RIGA. In male students, coping styles of "active" and "passive/avoidant", "aggressive" influenced RIGA factors of "maladaptive behaviors" and "negative emotional experience". In female students, coping styles of seeking social support related positively to RIGA; coping styles of "active", "passive/avoidant", and "aggressive" influenced "maladaptive behaviors", "negative emotional experience", and coping styles of "active" and "passive/avoidant", "seeking social support" influenced "low academic attitude", RIGA factors, respectively. Coping styles of "active", "passive/avoidant", "aggressive", and "seeking-social-support" influenced "psychological absorption and fixation".

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1673-1678
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• 2005

This paper addresses both theoretical and experimental studies of the stability of haptic interfaces during the simulation of virtual Coulomb friction. The first objective of this paper is to present an analysis of how friction affects stability in terms of the describing function method and the absolute stability theory. Two different feedback methods are introduced and are used to evaluate the analysis: an active force feedback, using a motor, and a passive force feedback, using controllable brake. The second objective of this paper is to present a comparison of the theoretical and experimental results. The results indicate that the sustained oscillations due to the limit cycle occur when simulating friction with an active force feedback. In contrast, a passive force feedback can simulate virtual friction without the occurrence of instability. In conclusion, a hybrid active/passive force feedback is proposed to simulate a highly realistic friction display.

• PNF and Movement
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• v.20 no.2
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• pp.215-222
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• 2022

Purpose: The purpose of this study was to compare the effects of passive scapular upward rotation and posterior tilt and active scapular posterior tilt on the muscle activity of the upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA). Methods: Fifteen healthy subjects performed general arm elevation, arm elevation with passive scapular upward rotation and posterior tilt, and arm elevation with active scapular posterior tilt. For active scapular posterior tilt, the subjects were trained in this movement using visual biofeedback and a motion sensor. During each arm elevation condition, electromyography was used to measure the muscle activity of the UT, LT, and SA. The measured data were analyzed using a one-way repeated ANOVA. Results: LT muscle activity was significantly increased during arm elevation with active scapular posterior tilt compared to both general arm elevation and arm elevation with passive scapular upward rotation and posterior tilt (p < 0.05). SA muscle activity was greater during arm elevation with passive scapular upward rotation and posterior tilt than during general arm elevation (p < 0.05). There was no significant change in UT muscle activity among the tested arm elevation conditions (p > 0.05). Conclusion: Performing arm elevation with active scapular posterior tilt and performing arm elevation with passive scapular upward rotation and posterior tilt may be useful strategies for increasing muscle activation of the LT and SA, respectively.

• The Journal of Information Systems
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• v.27 no.3
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• pp.81-102
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• 2018

Purpose The purpose of this study is to investigate the reason why smartphone users do not use mobile banking based on Status Quo Bias and to find out whether there is a difference between passive resistance and active resistance. Design/methodology/approach This study made a design of the research model based on Status Quo Bias. SPSS 23.0 and SmartPLS 2.0 were used for the analysis. Multiple group analysis was performed to identify differences between groups. Findings According to the empirical analysis result, this study confirmed that inertia and perceived risk affected smartphone users who do not use mobile banking. According to the type of resistance, the active resistance group(64.2%) was more than the passive resistance group(35.8%), and it was confirmed that there was a difference in the reasons for not using mobile banking between passive and active resistance group. That is, the greatest difference between passive and active resistance groups was found to be perceived risk, which is an assessment of risk.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.179-183
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• 2001

Vibration isolation of mechanical systems, in general is achieved through either passive or active vibration control system. Although passive vibration isolators offer simple and reliable means to protect mechanical system from vibration environment, passive vibration isolator has inherent performance limitation. Whereas, active vibration isolator provide significantly superior vibration-isolation performance. Recently, many studied and applications are carried out in this field. In this study, vibration-isolation characteristics of active vibration control system using electromagnetic force actuator are investigated. Some control algorithms. Optimal Feedforward are used for active vibration isolation. Form the experimental results of each control algorithms, active vibration isolation characteristics are investigated.