• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.97-104
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• 2005

The seismic behavior of framed structure with Chevron-type bucking restrained braces were investigated and their behavior factors were evaluated following the procedure proposed in ATC-19 & ATC-34. Two types of structures, building frame systems and dual systems, with 4, 8, 12, and 16 stories were designed per the IBC 2000, the AISC LRFD and the AISC/SEAOC Recommended Provisions for BRBF. Nonlinear static pushover analyses were carried out to observe the plastic hinge formation and to identify the loads and the displacements at the yield and the ultimate states. Time history analyses were also carried out to compute the permanent displacement md the dissipated hysteretic energy. According to the analysis results, the response modification factors of model structures fumed out to be larger than what is proposed in the provision in low story structures, and a little smaller in medium-story structures. The dual systems, even though designed with smaller seismic load, showed superior static and dynamic performances.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1700-1706
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• 2016

In this paper, a dual-stator, spoke-type linear vernier machine (DSSLVM) for wave energy extraction application was proposed. This machine is capable of producing a competitively high thrust force and force density at a low operation speed in direct drive systems. The operation principal and working of the proposed DSSLVM were studied. The stator core height is adjusted to improve the overall force density of the proposed machine while reducing the force ripple. To evaluate the advantages of the proposed DSSLVM, the main performance was compared with that of a recently developed linear primary permanent magnet vernier machine (LPPMVM). The proposed machine exhibited greater thrust force and force density, an improved power factor and lower force ripple with the same permanent magnet (PM) volume compared to the LPPMVM.

• International Journal of Automotive Technology
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• v.8 no.6
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• pp.675-685
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• 2007

A single cylinder SI engine with a VVA system is modeled by the coupling of a commercial 1D simulation package and an additional combustion model and validated by comparison with experimental data. A number of simulations are carried out to investigate the effects of five different VVA systems on the performance and fuel efficiency of the baseline engine. Finally, the simulation model is applied to an extensive computational study to map out the strategies to operate the engines with dual CVVT and dual CVVT-2 step VVL systems in a fuel-efficient manner.

• Industrial Engineering and Management Systems
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• v.7 no.3
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• pp.197-203
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• 2008

Many quality engineering practitioners continue to have a considerable interest in implementing the concept of response surface methodology to real situations. Recently, dual response surface approach is extensively studied and recognized as a powerful tool for robust design. However, existing methods do not consider the information provided by customers and design engineers. In this regard, this article proposes a flexible optimization model that incorporates that information via desirability function modeling. The optimization scheme and its modeling flexibility are demonstrated through an illustrative example by comparing the proposed model with existing ones.

• Journal of Aerospace System Engineering
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• v.4 no.1
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• pp.19-22
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• 2010

The accuracy and integrity of global navigation satellite systems (GNSS) can be improved by using GNSS augmentation systems. Large ionospheric spatial gradient, during ionosphere storm, is a major threat for using GNSS augmentation systems by increasing the spatial decorrelation between a reference system and users. Ionosphere decorrelation behavior can be analyzed by using dual frequency GPS data. GNSS receivers have their own biases, called inter-frequency bias (IFB) between dual(P1 and P2) frequencies and they must be accurately estimated before computing ionosphere delays. GPS network data in Korea is used to compute each receiver's IFB, and their estimation accuracy and variability are analyzed. IFB estimation methodology to apply for ionosphere gradient analysis is discussed.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.330-335
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• 2013

This paper performs two kinds of Field-Oriented Control (FOC) for dual three phase permanent magnet synchronous motor (DTP-PMSM).The first is based on vector space decomposition to study the effect of current harmonics on electromechanical energy conversion. And the second presents the coupling relations between two sets of windings using two d-q transformation. And then this paper has deeply studied the differences between these two strategies, the different effect on the control of harmonic current and the reason for these differences. MATLAB-based Simulation studies of a 3KW DTP-PMSM are carried out to verify the analysis of differences between the two FOC strategies.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.8
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• pp.55-62
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• 2012

The development of memory design and process technology enabled the production of high density memory. As the weight of embedded memory within aggregate Systems-On-Chips(SoC) gradually increases to 80-90% of the number of total transistors, the importance of testing embedded dual-port memories in SoC increases. This paper proposes a new micro-code based programmable memory Built-In Self-Test(PMBIST) architecture for dual-port memories that support test various test algorithms. In addition, various test algorithms including March based algorithms and dual-port memory test algorithms are efficiently programmed through the proposed algorithm instruction set. This PMBIST has an optimized hardware overhead, since test algorithm can be implemented with the minimum bits by the optimized algorithm instructions.

• Tribology and Lubricants
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• v.33 no.3
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• pp.85-91
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• 2017

This work studies the flow behaviors in the gap between the friction pad and separator in wet-clutch systems. The fluid volume of the lubricant is modeled using the entire system of wet-clutch pack of a dual clutch transmission that has larger outer radius of odd gear shifts and smaller inner radius of even gear shifts. Flow behaviors in the gap of the clutch pad are computed using the gear shift modes that consider the real relative velocities between the friction pad and separator. Flow behaviors in the gap of the disengaged clutch pad are mainly investigated for the wet-clutch system, whereas the engaged clutch pad is modeled with no fluid rate through the contacting surfaces. The developed hydrodynamic fluid pressures and velocity fields in the clutch pad gap are computed to obtain the relevant information for managing flow rates in wet-clutch packs under dual operating conditions during gear shifts. These hydrodynamic pressures and velocity fields are compared on the basis of each gear level and gap location, which is necessary to determine the effects of groove patterns on the friction pad. Shear stresses in the gap locations are also computed on the basis of the gear level for the inner and outer clutch pads. The computed results are compared and used for the design of cooling capacity against frictional heat generation in wet-clutch pack systems.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1609-1618
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• 2015

DC microgrids are considered as prospective systems because of their easy connection of distributed energy resources (DERs) and electric vehicles (EVs), reduction of conversion loss between dc output sources and loads, lack of reactive power issues, etc. These features make them very suitable for future industrial and commercial buildings' power systems. In addition, the bipolar-type dc system structure is more popular, because it provides two voltage levels for different power converters and loads. To keep voltage balanced in such a dc system, a bidirectional dual buck-boost voltage balancer with direct coupling is introduced based on P-cell and N-cell concepts. This results in greatly enhanced system reliability thanks to no shoot-through problems and lower switching losses with the help of power MOSFETs. In order to increase system efficiency and reliability, a novel burst-mode control strategy is proposed for the dual buck-boost voltage balancer. The basic operating principle, the current relations, and a small-signal model of the voltage balancer are analyzed under the burst-mode control scheme in detail. Finally, simulation experiments are performed and a laboratory unit with a 5kW unbalanced ability is constructed to verify the viability of the bidirectional dual buck-boost voltage balancer under the proposed burst-mode control scheme in low-voltage bipolar-type dc microgrids.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.311-317
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• 2016

Many services have been developed that are based on smart devices, and security between devices is emphasized. A beacon on the current IoT(Internet of Things) services has been utilized in the commercial field and is being applied to the services of the home IoT. On the other hand, the beacon is weak to security using Bluetooth-based services. Therefore, it is important to strengthen the security of the beacon. This paper proposes a dual security technique that can enhance the security of beacon-based services. The dual security architecture and security process is proposed based on beacon and authentication service. In addition, mobile application was developed and validated based on the beacon for proving the suitability of the proposed technique. The experimental method for verification are the authentication failure case, such as 1st authentication fail, and authentication success case, such as 1st authentication success and 2nd authentication success. The components of the verification experiments consists of two beacons (matched with Beacon ID, mismatched with Beacon ID), one mobile device and authentication application. This was tested to verify the compatibility of the dual security architecture and 1st/2nd authentication process.