• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.65-70
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• 2008

The capacity spectrum method (CSM) is a deterministic seismic analysis approach wherein the expected seismic response of a structure is established as the intersection of the demand and capacity curves. Recently, there are a few studies about a probabilistic CSM where uncertainties in design factors such as material properties, loads, and ground motion are being considered. However, researches show that soil-structure interaction also affects the seismic responses of structures. Thus, their uncertainties should also be taken into account. Therefore, this paper presents a probabilistic approach of using the CSM for seismic analysis considering uncertainties in soil properties. For application, a reinforced concrete bridge column structure is employed as a test model. Considering the randomness of the various design parameters, the structure's probability of failure is obtained. Monte Carlo importance sampling is used as the tool to assess the structure's reliability when subjected to earthquakes. In this study, probabilistic CSM with and without consideration of soil uncertainties are compared and analyzed. Results show that the analysis considering soil structure interaction yields to a greater probability of failure, and thus can lead to a more conservative structural design.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.3
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• pp.18-24
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• 2003

The resonator using two layer microstrip structure was proposed and the bandpass filter was designed using this resonator in this paper. The proposed resonator structure is constructed by placing a U-shape of resonator in the first layer and then placing a broadside coupling strip in the second layer just above of the U-shape of resonator's edge part. Because these structure has various design parameters than general single layer coupled line structure, filter design is more flexible. In this paper, the narrow band filter was designed using multi-layer structure that had been applied to broadband filter because it's high coupling nature. The filter was designed to have 4MHz center frequency and 3 % fractional bandwidth, and finally confirmed that can be realizable narrow band filter by using multi-layer structure through fabrication and measurement.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1995-2003
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• 2014

Power semiconductor devices have been the major backbone for high-power electronic devices. One of important parameters in view of power semiconductor devices often characterize with a high breakdown voltage. Therefore, many efforts have been made, since the development of the Insulated Gate Bipolar Transistor (IGBT), toward having higher level of breakdown voltage, whereby the typical design thereof is focused on the structure using the field ring. In this study, in an attempt to make up more optimized field-ring structure, the characteristics of the field ring were investigated with the use of theoretical arithmetic model and methodologically the design of experiments (DOE). In addition, the IGBT having the field-ring structure was designed via simulation based on the finding from the above, the result of which was also analyzed. Lastly, the current study described the trench field-ring structure taking advantages of trench-etching process having the improved field-ring structure, not as simple as the conventional one. As a result of the simulation, it was found that the improved trench field-ring structure leads to more desirable voltage divider than relying on the conventional field-ring structure.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.2
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• pp.31-38
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• 2010

Bus manufacturers have tested and studied the dynamic collapse behavior of a bus body structure in rollover since UN ECE established ECE Regulation 66 to provide the requirement for the strength of bus structure. In spite of the costly cycles of practical tests, however, it is still a hard task to meet the rollover regulation by means of local reinforcements in the bus structure. Therefore it is necessary to develop a well designed strategy for the rollover strength implemented in the early stage of vehicle development. In this study, the suitable development method for each design stage from a component to complete body structure was considered to make a well-established development process of a bus body structure for rollover safety. For the efficient approach of the concept design stage, a numerical model based on the plastic hinge theory was used instead of detailed shell models. After setting up the concept design for the component size and geometry, the shell model was used to confirm and optimize the whole structure composition. The process developed in this study was practically used as an effective method to predict the rollover behavior of a new bus body structure.

• International Journal of Highway Engineering
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• v.19 no.4
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• pp.27-36
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• 2017

PURPOSES : The purpose of this study is to perform a reliability analysis of the proposed wind load combination which governs the design of support structures of subsidiary road facilities, and to evaluate whether the target reliability of the design is satisfied. METHODS : The statistical estimation method is applied and the design period of the support structure is used to obtain the statistical property of the wind load. In addition, the statistical properties of the strength of support structures are obtained from a literature review and simulation study. Actual support structures are designed by the proposed load combination and are used as the examples to examine if the target reliability is obtained. RESULTS : The result of the reliability analysis performed by using the statistical properties of load and resistance for the support structure in this study indicates that the proposed wind load combination satisfied the target reliability index of the design. Also, the convenience of the design is achieved by adopting the same design wind velocity given in the bridge design code by applying the wind velocity ratio defined for the design period of the support structure. CONCLUSIONS : It is presented that the design using the wind load combination proposed in this study achieved the target reliability index and the design wind load for different design periods can be conveniently defined by applying the velocity ratio proposed in this study.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.1-4
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• 2002

The present study aims to design a multiplayer microstrip antenna with composite sandwich construction and to estimate structural behavior of this multiplayer structure for the next generation of structural surface technology. This is termed Surface-Antenna-Structure indicating that structural surface becomes antenna. Constituent materials were selected considering electrical properties as well as mechanical properties. For the antenna performance, antenna elements inserted into structural layers were designed for satellite communication at a resonant frequency of 12.5 GHz and final demonstration article was $16\times16$ array antenna. From electrical measurements it was shown that antenna performances were in good agreement with design requirements. Structural analysis showed this antenna structure was well designed for the mechanical rigidity. All constituent materials were characterized independently. The SAS concept is the first serious attempt at integration for both antenna and composite engineers and promises innovative future communication technology.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.5
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• pp.63-72
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• 2001

In this paper, to satisfy the safety and economy immediately, we assume the center of lateral load in case the dynamic motion of the torsionally unbalanced structure is transformed into the static lateral load using modal analysis and proposes a method to control the design eccentricity in order to make the center of lateral load coincide with the center of strength. And when the structure is designed by proposed method, it is shown that the structure designed by proposed method does not demand excessive additional ductility in comparison with the structure designed by provisions of other seismic building code.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.416-420
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• 2004

Recently, the importance of vibration reduction at the local structure such as tank, deck which attached machinery and compass deck, has continuously increased by owner and shipbuilder. Because crews are afflicted with them and severe vibration problems affect on the crack of structure. This study conducted optimum design to get a stiffener size of local structure to reducing the vibration level and dec leasing the weight of structure in ship. Random tabu search method (R-Tabu) has fast converging time and can search variables size domains for nonlinear problems. This paper used Nastran external call type independence optimization method which makes using a solver module from Nastran.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.343-346
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• 2003

A new structure to design low pass filters (LPFs) is presented rho proposed structure has the etched shape of Quad-Spiral DGS(Defected Ground Structure) on microstrip transmission lines. By extracting the equivalent circuit elements of unit Quad-Spiral DGS, LPFs are designed easily. The equivalent circuit of Quad-Spiral DGS consists of a step impedance resonator and lumped elements. The proposed LPF provided steep rejection characteristics with 5-poles. Experimental results show excellent agreements with circuit simulation results in wide band and the validity of our circuit modeling for LPF design. The result shows another possibility of Quad Spiral DGS for microwave devices.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.848-849
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• 2015

This paper presents the structure design for optimizing output power density and efficiency to develop a spoke-type interior permanent magnet synchronous generator (IPMSG). To obtain the optimal structure, the combination of response surface method (RSM) and 2-D finite element analysis can solve the problem effectively for reducing the volume of permanent magnets (PMs) and maximizing the ratio between power density and efficiency. The effectiveness of this proposed structure design is verified by the simulation and experiment according to the comparison of the electromagnetic characteristics between the initial and modified structure.