• Smart Structures and Systems
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• v.25 no.5
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• pp.515-530
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• 2020

A new type of pure torsional yielding damper made from steel pipe is proposed and introduced. The damper uses a special mechanism to apply force and therefore applies pure torsion in the damper. Uniform distribution of the shear stress caused by pure torsion resulting in widespread yielding along pipe and consequently dissipating a large amount of energy. The behavior of the damper is investigated analytically and the governing relations are derived. To examine the performance of the proposed damper, four types of the damper are experimentally tested. The results of the tests show the behavior of the system as stable and satisfactory. The behavior characteristics include initial stiffness, yielding load, yielding deformation, and dissipated energy in a cycle of hysteretic behavior. The tests results were compared with the numerical analysis and the derived analytical relations outputs. The comparison shows an acceptable and precise approximation by the analytical outputs for estimation of the proposed damper behavior. Therefore, the relations may be applied to design the braced frame system equipped by the pure torsional yielding damper. An analytical model based on analytical relationships was developed and verified. This model can be used to simulate cyclic behavior of the proposed damper in the dynamic analysis of the structures equipped with the proposed damper. A numerical study was conducted on the performance of an assumed frame with/without proposed damper. Dynamic analysis of the assumed frames for seven earthquake records demonstrate that, equipping moment-resisting frames with the proposed dampers decreases the maximum story drift of these frames with an average reduction of about 50%.

• Journal of the Korean Wood Science and Technology
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• v.36 no.4
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• pp.102-108
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• 2008

At the University of Maine, a hemicellulose pre-extraction technology is now being investigated to improve pulp yields, reduce the organic and inorganic load for liquor recovery, and create a feed stream for the generation of new biomaterials. It is important to understand the composition of unextracted wood, extracted wood, and pulping extracts in the design of an economically viable pilot-scale ethanol plant. For analysis of wood pulp composition, the total analytical mass balance closure was 100.6, 100.3, and 81.6% for unextracted chips, extracted chips, and pulping extracts from HPLC-H column analysis. Meanwhile, the total analytical mass balance from the HPLC-P column was 97.8, 86.3, and 80.7%, respectively. This slight variability between H- and P-column results for analytical mass balance may be within the experimental error of the measurement. The data generated by this analysis are important to further design work in commercializing this process.

• Journal of Korean Institute of Industrial Engineers
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• v.35 no.1
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• pp.51-57
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• 2009

There are a variety of users and devices in a context-aware computing environment. In this environment, the service provided to a user may be the composition of diverse services rather than one independent service. Before user's devices provide the composite service to the user, they should perceive user's needs by gathering related information segments from other surrounding devices and/or sensors. We consider a context-aware computing environment providing composite and adapted service to users and propose an information processing model that characterizes the device where the collected data should be processed through services and/or applications. Based on this model, we provide an analytical tool to obtain some performance measures of the context-aware computing environment.

• Computers and Concrete
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• v.17 no.2
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• pp.227-240
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• 2016

An analytical study was conducted to investigate the effect of the shape and spacing of modified inclined studs used as shear connector between concrete and steel plate on the cyclic behavior of steel plate concrete (SC) shear wall. 9 different analysis cases were adopted to determine the optimized shape and spacing of stud. As the results, the skeleton curves were obtained from the load-displacement hysteresis curves, and the ultimate and yielding strengths were increased as the spacing of studs decrease. In addition, the strength of inclined studs is shown to be bigger compared to that of conventional studs. The damping ratios increased as the decrease of stiffness ratio. Finally, with decreasing the spacing distance of studs, the cumulative dissipated energy was increased and the seismic performance was improved.

• Structural Engineering and Mechanics
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• v.43 no.3
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• pp.287-309
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• 2012

Precast segmental bridge columns (PSBC) are alternatives for monolithic cast-in-situ concrete columns in bridge substructures, with fast construction speed and structural durability. The analytical tool for common use is demonstrated applicable for seismic performance prediction of PSBCs through experiment conducted earlier. Then the analytical program was used for parameter optimization of PSBC configurations under reversal cyclic loading. Shear strength by pushover analysis was compared with theoretical prediction. Moreover, seismic response of PSBC with energy dissipation (ED) bars was compared with its no ED bar counterpart under three history ground acceleration records. The investigation shows that appropriate ED bar and post-tensioned tendon arrangement is important for higher lateral bearing capacity and good ductility performance of PSBCs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.4
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• pp.1077-1088
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• 1996

In this paper, we propose a new method to analyze the performance degradation by timing jitters in the receivers of intensity modulation/direct detection digital optical communication systems where pulse-shaping filters are used to minimize intersymbol interference. The results obtained from the proposed analytical method show that conventional analytical methods underestimate the influence of timing jitters on the receiver performance. Using the proposed anlaytical method, we derive an analytic equation for approximated power penalty due to timing itters and obtain an exact power penalty by numerical analyses. Assuming Gaussian or uniform probability density function for timing jitters, we also show that assumption of Gaussian distribution for timing jitters yields more performance degration than that of uniform distribution.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.4
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• pp.329-333
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• 2003

In this paper we analyze the performance of the low latency pre-registration handoff method of mobile IP by computer simulation. Packet losses and delays are evaluated in terms of system utilization. Foreign agents that participate in the handoff process can be modeled as queues representing input and output ports. Therefore, we propose an analytical model of pre-registration handoff by using open queueing network model. Simulation results are shown for validating analytical estimates.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.48-54
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• 2012

In this paper, quantitative and systematic procedures for establishing Key Performance Indicators (KPI's) of R&D departments are presented. The proposed methodology is composed of 4 steps : 1) identification of critical success factors, 2) identification of potential KPI's, 3) determination of KPI's and 4) monitoring and execution. A Strategy Map has been presented to better align KPI's with a company's competitive strategies. Also, Analytical Hierarchy Planning (AHP) is used to determine weights of KPI's and Data Envelopment Analysis (DEA) is used to analyze the effectiveness of R&D departments. To demonstrate its validity of the proposed method, it has been applied to the R&D divisions of a semiconductor company.

• Journal of Communications and Networks
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• v.13 no.2
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• pp.142-148
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• 2011

Because currently available wireless technologies are not appropriate for wireless body area networks (WBANs), the IEEE 802.15.6 standard was introduced by the IEEE 802.15.6 Task Group to satisfy all the requirements for a monitoring system that operates on, in, or around the human body. In this work, we develop an analytical model for evaluating the performance of an IEEE 802.15.6-based WBAN under saturation condition and a noisy channel. We employ a three-dimensional Markov chain to model the backoff procedure as specified in the standard. Probability generating functions (PGFs) are used to compute the performance descriptors of the network. The results obtained from the analytical model are validated by simulation results. Our results indicate that under saturation condition, the medium is accessed by the highest user priority nodes at the vast majority of time while the other nodes are starving.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.603-610
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• 2008

In this paper, analytical methods for calculating the average probability of bit error of direct sequence pulse amplitude modulation ultra wideband (DS-PAM UWB) system and time hopping pulse position modulation ultra wideband (TH-PPM UWB) system are given. For the multi-user DS-PAM UWB system, the bipolar pulse amplitude modulation is used in order to achieve better performance. As we know, more attention is paid to the TH-PPM UWB systems recently. In this paper. we first introduce the accurate BER calculation methods of the multi-user DS-PAM UWB and TH-PPM UWB systems and then give the performance analysis over the ideal AWGN channel and a correlation receiver. Furthermore, we also introduce their applications in image transmission and data transmission and give the simulation results. The analytical method yields simple and exact formulas relating the performance to the system parameters.