• Journal of Welding and Joining
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• v.26 no.2
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• pp.85-91
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• 2008

In general, the quality of a welding process tends to vary with depending on the work environment or external disturbances. Hence, in order to achieve the desirable quality of welding, we should have the optimal welding condition that is not significantly affected by these changes in the environment or external disturbances. In this study, we used a dual response surface method in consideration of both the mean output variables and the standard deviation in order to optimize the V-groove arc welding process. The input variables for GMA welding process with the dual response surface are welding voltage, welding current and welding speed. The output variables are the welding quality function using the shape factor of bead geometry. First, we performed welding experiment on the interested area according to the central composite design. From the results obtained, we derived the regression model on the mean and standard deviation between the input and output variables of the welding process and then obtained the dual response surface. Finally, using the grid search method, we obtained the input variables that minimize the object function which led to the optimal V-groove arc welding process.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.12
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• pp.7-12
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• 2008

In this paper, a highly efficiency power amplifier is presented for multi-band antenna system. The class F power amplifier operating in dual-band designed with one LDMOSFET. An operating frequency of power amplifier is 900 MHz and 2.14 GHz respectively Matching networks and harmonic control circuits of amplifier are designed by using the unit cell of composite right/left-handed(CRLH) transmission line(TL) realized with lumped elements. The CRLH TL can lead to metamaterial transmission line with the dual-band holing capability. The dual-band operation of the CRLH TL is achieved by the frequency offset and the nonlinear phase slope of the CRLH TL for the matching network of the power amplifier. Because the control of all harmonic components for high efficiency is very difficult, we have controled only the second- and third-harmonics to obtain the high efficiency with the CRLH TL. Also, the proposed power amplifier has been realized by using the harmonic control circuit for not only the output matching network, but also the input matching network for better efficiency.

• Earthquakes and Structures
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• v.12 no.3
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• pp.263-270
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• 2017

In this study, two geometrically identical multi-storey steel buildings with different lateral load resisting systems are structurally analyzed under same earthquake conditions and they are compared with respect to their construction costs of their structural systems. One of the systems is a steel structure with eccentrically steel braced frames. The other one is a RC wall-steel frame system, that is a steel framed structure in combination with a reinforced concrete core and shear walls of minimum thickness that the national code allows. As earthquake resisting systems, steel braced frames and reinforced concrete shear walls, for both cases are located on identical places in either building. Floors of both buildings will be of reinforced concrete slabs of same thickness resting on composite beams. The façades are assumed to be covered identically with light-weight aluminum cladding with insulation. Purpose of use for both buildings is an office building of eight stories. When two systems are structurally analyzed by FEM (finite element method) and dimensionally compared, the dual one comes up with almost 34% less cost of construction with respect to their structural systems. This in turn means that, by using a dual system in earthquake zones such as Turkey, for multi-storey steel buildings with RC floors, more economical solutions can be achieved. In addition, slender steel columns and beams will add to that and consequently more space in rooms is achieved.

• Journal of Advanced Navigation Technology
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• v.17 no.2
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• pp.196-201
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• 2013

In this paper, a dual-mode balanced filter with symmetric coupled composite right/left-handed transmission line is introduced. Unlike the other symmetric structure, this configuration has the ability to operate under both common- and differential-mode excitation. These properties are achievable through providing physical short circuit by means of ground vias at the center of each unit-cell along the symmetry plane of the structure. Because the CRLH unit-cells are operated under both common- and differential-mode excitation, we implemented a balanced filter using these properties. To validity these features, a five-cell four port coupled CRLH-TL is simulated, fabricated and measured and the obtained performances agree with the simulation results under both common- and differential-mode excitation.

• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.357-363
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• 2021

We developed a chemiresistive anion sensor using highly conductive carbon nanotube fibers (CNTFs) functionalized with anion receptors. Mechanically robust CNTFs were prepared via wet-spinning utilizing the nematic liquid crystal properties of CNTs in chlorosulfonic acid (CSA). For anion detection, polymeric receptors composed of dual-hydrogen bond donors, including thiourea 1, squaramide 2, and croconamide 3, were prepared and bonded non-covalently on the surface of the CNTFs. The binding affinities of the anion receptors were studied using UV-vis titrations. The results revealed that squaramide 2 exhibited the highest binding affinity toward AcO^-, followed by thiourea 1 and croconamide 3. This trend was consistent with the chemiresistive sensing responses toward AcO^- using functional CNTFs. Selective anion sensing properties were observed that CNTFs functionalized with squaramide 2 exhibited a response of 1.08% toward 33.33 mM AcO^-, while negligible responses (<0.1%) were observed for other anions such as Cl^-, Br^-, and NO₃^-. The improved response was attributed to the internal charge transfer of dual-hydrogen bond donors owing to the deprotonation of the receptor upon the addition of AcO^-.

• Steel and Composite Structures
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• v.14 no.6
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• pp.621-636
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• 2013

Response modification factor is one of the seismic design parameters to consider nonlinear performance of building structures during strong earthquake, in conformity with the point that many seismic design codes led to reduce the loads. In the present paper it's tried to evaluate the response modification factors of dual moment resistant frame with buckling restrained braced (BRB). Since, the response modification factor depends on ductility and overstrength; the nonlinear static analysis, nonlinear dynamic analysis and linear dynamic analysis have been done on building models including multi-floors and different brace configurations (chevron V, invert V, diagonal and X bracing). The response modification factor for each of the BRBF dual systems has been determined separately, and the tentative value of 10.47 has been suggested for allowable stress design method. It is also included that the ductility, overstrength and response modification factors for all of the models were decreased when the height of the building was increased.

• Journal of IKEEE
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• v.22 no.4
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• pp.1050-1055
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• 2018

In this paper, we analyzed the sensitivity of matching elements for the dual-band operation of a power amplifier with composite right/left-handed (CRLH) transmission lines. Metamaterial theory enables CRLH transmission to support arbitrary impedance matching at dual frequencies. In general, at sub-GHz range, the CRLH matching networks are commonly implemented with lumped elements, which are prone to manufacturing distribution. In order to reduce the effect from the distribution of element values in design, we suggest a method to analyze the sensitivity of matching elements from the performance aspect of power amplifiers. Based on the analysis, a 40dBm dual-band power amplifier operating at 0.7GHz and 1.5GHz is designed.

• Steel and Composite Structures
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• v.38 no.4
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• pp.355-363
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• 2021

The present paper attempts to investigate the propagation of plane waves in an isotropic elastic medium under the effect of initial stress and temperature-dependent properties. The modulus of elasticity is taken as a linear function of the reference temperature. The formulation is applied under the thermoelasticity theory with dual-phase-lag; the normal mode analysis is used to obtain the expressions for the displacement components, the temperature, the stress, and the strain components. Numerical results for the field quantities are given in the physical domain and illustrated graphically. Comparisons are made with the results predicted by different theories (Lord-Shulman theory, the classical coupled theory of thermoelasticity and the dual-phase-lag model) in the absence and presence of the initial stress as well as the case where the modulus of elasticity is independent of temperature.

• Steel and Composite Structures
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• v.44 no.1
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• pp.105-117
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• 2022

Impact resistance efficiency of the newly designed sandwich beam with a laterally arched core as bio-inspired by the woodpecker is numerically investigated. The principal components of the beam comprise a dual-core system sandwiched by the top and bottom laminated CFRP skins. Different materials, including hot melt adhesive, high-density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS), epoxy resin (EPON862), aluminum (Al6061), and mild carbon steel (AISI1018), are considered for the side-arched core layer of the beam for impact efficiency assessment. The aluminum honeycomb takes the role of the second core. Contact force, stress, damage formation, and impact energy for beams equipped with different materials are examined. A diversity in performance superiority is noticed in each of these indicators for different core materials. Therefore, for overall performance appraisal, the impact resistance efficiency index, which covers several chief impact performance parameters, of each sandwich beam is computed and compared. The impact resistance efficiency index of the structure equipped with the AISI1018 core is found to be the highest, about 3-10 times greater than other specimens, thus demonstrating its efficacy as the optimal material for the bio-inspired dual-core sandwich beam system.

• Steel and Composite Structures
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• v.37 no.4
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• pp.447-462
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• 2020

In this paper, a simplified seismic design method for low-rise dual frame-steel plate shear wall (SPSW) structures is proposed in the framework of performance-based seismic design. The dynamic response of a low-rise structure is mainly dominated by the first-mode and the structural system can be simplified to an equivalent single degree-of-freedom (SDOF) oscillator. The dual frame-SPSW structure was decomposed into a frame system and a SPSW system and they were simplified to an equivalent F-SDOF (SDOF for frame) oscillator and an equivalent S-SDOF (SDOF for SPSW) oscillator, respectively. The analytical models of F-SDOF and S-SDOF oscillators were constructed based on the OpenSees platform. The equivalent SDOF oscillator (D-SDOF, dual SDOF) for the frame-SPSW system was developed by combining the F-SDOF and S-SDOF oscillators in parallel. By employing the lateral force resistance coefficients and seismic demands of D-SDOF oscillator, the design approach of SPSW systems was developed. A 7-story frame-SPSW system was adopted to verify the feasibility and demonstrate the design process of the simplified method. The results also show the seismic demands derived by the equivalent dual SDOF oscillator have a good consistence with that by the frame-SPSW structure.