• Structural Engineering and Mechanics
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• v.69 no.5
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• pp.567-577
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• 2019

Guyed steel lattice towers (or guyed masts) are widely used for supporting antennas for telecommunications and broadcasting. This paper presents a numerical study on the static and dynamic response of guyed towers. Three-dimensional nonlinear finite-element models are used to simulate the response. Through performing static pushover analyses and free-vibration (modal) analyses, the effect of different bracing configurations is investigated. In addition, seismic analyses are performed on towers of different heights to study the influence of earthquake excitation time-lag (or the earthquake travel distance between tower anchors) and antenna weight on the seismic response of guyed towers. The results show that the inclusion of time lag in the seismic analysis of guyed towers can influence shear and moment distribution along the height of the mast. Moreover, it is found that the lateral response is insensitive to bracing configurations. The results also show that, depending on the mast height, an increased antenna weight can reduce the tower maximum base shear while other response quantities, such as cables tension force are found to be insensitive to variation in the antenna weight.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.2
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• pp.227-245
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• 2013

Reliable strength assessment of the Liquefied Natural Gas (LNG) cargo containment system under the sloshing impact load is very difficult task due to the complexity of the physics involved in, both in terms of the hydrodynamics and structural mechanics. Out of all those complexities, the proper selection of the design sloshing load which is applied to the structural model of the LNG cargo containment system, is one of the most challenging one due to its inherent randomness as well as the statistical analysis which is tightly linked to the design sloshing load selection. In this study, the response based strength assessment procedure of LNG cargo containment system has been developed and proposed as an alternative design methodology. Sloshing pressure time history, measured from the model test, is decomposed into wavelet basis function targeting the minimization of the number of the basis function together with the maximization of the numerical efficiency. Then the response of the structure is obtained using the finite element method under each wavelet basis function of different scale. Finally, the response of the structure under entire sloshing impact time history is rapidly calculated by synthesizing the structural response under wavelet basis function. Through this analysis, more realistic response of the system under sloshing impact pressure can be obtained without missing the details of pressure time history such as rising pattern, oscillation due to air entrapment and decay pattern and so on. The strength assessment of the cargo containment system is then performed based on the statistical analysis of the stress peaks selected out of the obtained stress time history.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.130-142
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• 2019

For a preemptive strike against a Time Critical Target(TCT), such as Transporter-Erector-Launcher(TEL), the detection capability of capturing launch signals in the Area of Interest(AoI) is important. In this study, the characteristics of the revisit time and the response time of 6~48 small SAR constellation satellites were analyzed. In particular, the revisit time was analyzed for all regions of North Korea and specific regions, and the response time was classified into [Scenario 1] to identify fixed targets and [Scenario 2] to detect and identify moving targets. In particular, the response time analysis for the TCT detection mission operation in [scenario 2] was performed through optimization analysis of observation cumulative coverage for a specific area. Finally, the configuration of constellation satellites for optimal performance of the detection mission was estimated.

• Earthquakes and Structures
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• v.7 no.3
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• pp.349-365
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• 2014

The dynamic response of structures under extremely short duration dynamic loads is of great concern nowadays. This paper investigates structures' response as well as the associated structural damage to explosive loads considering and ignoring the supporting soil flexibility effect. In the analysis, buildings are modeled by two alternate approaches namely, (1) building with fixed supports, (2) building with supports accounting for soil-flexibility. A lumped parameter model with spring-dashpot elements is incorporated at the base of the building model to simulate the horizontal and rotational movements of supporting soil. The soil flexibility for various shear wave velocities has been considered in the investigation. In addition, the influence of variation of lateral natural periods of building models on the obtained response and peak response time-histories besides damage indices has also been investigated under blast loads with different peak over static pressures. The Dynamic response is obtained by solving the governing equations of motion of the considered building model using a developed Matlab code based on the finite element toolbox CALFEM. The predicted results expressed in time-domain by the building model incorporating SSI effect are compared with the corresponding model results ignoring soil flexibility effect. The results show that the effect of surrounding soil medium leads to significant changes in the obtained dynamic response of the considered systems and hence cannot be simply ignored in damage assessment and response time-histories of structures where it increases response and amplifies damage of structures subjected to blast loads. Moreover, the numerical results provide an understanding of level of damage of structure through the computed damage indices.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.9
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• pp.179-185
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• 2013

In this paper, the RTA-ERP(Response Time Aligned-Evoked Relative Potential) was modelled to analyze the effect of motor activation pattern in response to visual sensory stimuli. Simon effect was analysed using the amplitude response of RTA-ERP and measured response time. The 'odd number' experiments, which identify an odd number mixed with same numbers, was performed with 15 healthy adult participants(9 males and 6 females, whose mean age of 31) for 7 minutes for each participant. Throughout experimentation, we observed that the proposed RTA-ERP can compensate the timing variation due to different neural processing procedures in the brain, and shows enhanced LRP(Lateralized Readiness Potential) and Pe(Error Related Positivity). Regarding to 'congruence' and 'incongruence' testing patterns, the amplitude of RTA-ERP and the response time for the 'congruence' are $0.03{\mu}V$ larger, and 43 ms faster than those for the 'incongruence', respectively. The amplitude characteristics of RTA-ERP, obtained by synchronizing the onset times with respect to response time, corresponds more likely to that of P300 in the ERP pattern (the characteristics of the Simon effect).

• The KIPS Transactions:PartC
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• v.15C no.4
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• pp.321-328
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• 2008

In this paper, we analyze web response time depending on queue managements and transmission latencies in highly congested network situation. Under FIFO scheme, the response times are for three different sizes of queue are almost the same, but the response time increases as traffic intensity increases. The performance between different queue sizes shows more different in 90% and 98% traffic intensity than in 80% traffic intensity. Especially the difference becomes bigger in short latency case than long latency case. Under RED scheme, three differently tunned RED schemes do not impact on the response time when the size of queue is relatively large. When the queue size becomes smaller, the response time of the differently tunned RED schemes becomes different for short latency case while the response times are almost same for long latency case. When comparing FIFO and RED schemes under same size of queue, RED scheme shows less response time than that of FIFO for the long latency case in high traffic intensity.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.5
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• pp.190-196
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• 2002

In this paper, the response characteristics of CAN-based feedback control system are analyzed when message time delays through the network are considered. The message time delays are composed of computation time delay and communication time delay. The application layer of CAN communication is modeled mathematically to analyze two time delays, and the communication time delay is redefined under several assumption conditions. The CAN-based feedback control system is proposed as a target system that is the machining system with the three axes. The response characteristics of time delays in the proposed system are analyzed through computer simulations, and can be improved by the compensation using the PID tuning method to satisfy the design specifications of the system.

• Computers and Concrete
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• v.8 no.6
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• pp.693-715
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• 2011

The main object of this study is to evaluate the seismic response effects on a reinforced concrete building isolated by triple concave friction pendulum (TCFP) bearings. The site-response effects arise from the difference in the local soil conditions at the support points of the buildings. The local soil conditions are, therefore, considered as soft, medium and firm; separately. The results on the responses of the isolated building are compared with those of the non-isolated. The building model used in the time history analysis, which is a two-dimensional and eight-storey reinforced concrete building with and without the seismic isolation bearings and/or the local soil conditions, is composed of two-dimensional moment resisting frames for superstructure and of plane elements featuring plane-stress for substructure. The TCFP bearings for isolating the building are modelled as of a series arrangement of the three single concave friction pendulum (SCFP) bearings. In order to investigate the efficiency of both the seismic isolation bearings and the site-response effects on the buildings, the time history analyses are elaborately conducted. It is noted that the site-response effects are important for the isolated building constructed on soft, medium or firm type local foundation soil. The results of the analysis demonstrate that the site-response has significant effects on the response values of the structure-seismic isolation-foundation soil system.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.43-51
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• 1998

Most of fuel-injection system operated with mechanical methods are difficult to control the injection quantity and injection timing as well as injection rate exactly. Moreover high pressure injection scheme is never be realized with conventional one. On the other hand, serious air pollution can be lessened with injection system equipped with those functions. Therefore, electronically controlled Unit Injuctor(UI) appeared to satify above mentioned desires. However, it is still difficult that the most important part, especially solenoid valve, is analyzed precisely, because of the existence of complex combination of electromagnetics, electrics and dynamic problems. In this study, experimental and theoretical analysis are accomplished for understanding of solenoid valve characteristics and further its design. As the result, the follows are obtained 1) As the increase of wire diameter, the response time became shorter and optimal inductance existed in relative with the response time and wire diameter. 2) According to increasing input voltage, the traction force increased, otherwise the response time was shortened. 3) As the increase of armature stroke, the traction force decreased and the response time became longer.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.59.5-59
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• 2002

In this paper, we present a robust controller design method that can not only deal with the constant time delay plant but also an uncertain time delay one. For a constant time delay plant. The proposed DTC can independently adjust the set response and the disturbance response without any stability constraint. And in the uncertain time delay case, one can process the control design step with uncertainty norm bound. To verify real effectiveness, theoretical analysis and simulation results are given.