• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.12
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• pp.1129-1132
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• 2005

The purpose of this reserch is to establish the new design technology for microwave Coplanar structure. The components in microwave circuit are classified to transmission devices, EM devices, and quasi-TEM devices. After design of these devices, we analyzed these CPWs electromagnetically using FDTD method, and suggested optimum CPW structure. In oder to realize a CPW module up to 30 GHz-100 GHz band, we research on a technology of 3-dimensional microwave CPW, and GaAs substrate with Si layer for ohmic loss. As a result this research, we suppressed the leakage, resonance, coupling, and radiation of CPW EMI, and improved resonance quality of CPW.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.2
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• pp.135-142
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• 2008

Experimental studies on the aerodynamic coupling effect on natural frequencies, critical speed and flutter instability of rotating disks are investigated in this paper. The theoretical analysis uses a fluid-structure model where the aerodynamic effects are represented in terms of elastic, lift and damping and stiffness components. The experiments performed using a vacuum chamber and ASMO/DVD disks rotating in vacuum, open and enclosure in several gaps with stationary wall give three main results. One is that the aerodynamic effect by the surrounding air reduces the natural frequencies and critical speeds of the vibration modes. The second is that natural frequency of disks rotating in open air is larger than that in enclosure. Finally, it is shown that the disk vibration is reduced as the gap between the disk and the rigid wall decreases.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.808-813
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• 2003

Maintaining agility and responsiveness m designing and manufacturing activities are the key issues for manufacturing companies to cope with global competition. Distributed design and control systems are regarded as an efficient solution for agility and responsiveness. However, distributed nature of a manufacturing system complicates production activities such as design, simulation, scheduling, and execution control. Especially, existing simulation systems have limited external integration capabilities, which make it difficult to implement complex control mechanisms for the distributed manufacturing systems. Moreover, integration and coupling of heterogeneous components and models are commonly required for the simulation of complex distributed systems. In this paper, a collaborative and adaptive simulation architecture is proposed as an open framework for simulation and analysis of the distributed manufacturing enterprises. By incorporating agents with their distributed characteristics of autonomy, intelligence, and goal-driven behavior, the proposed agent-based simulation architecture can be easily adapted to support the agile and distributed manufacturing systems. The architecture supports the coordination and cooperation relations, and provides a communication middleware among the participants in simulation.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.26-27
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• 2006

Characteristics of spatial structure of particle clusters are investigated by using the flow field data obtained from three-dimensional numerical simulations. Eulerian/Lagrangian approach with two-way coupling is applied and individual particle-particle collisions are taken into account by using the hard-sphere model. More than 16 million particles are traced in the maximum case. The results show that the cluster is consisted from the multiple-spatial scale components while the low wave-number, hence the large-scale structure, is dominant. Three-dimensional structure reconstructed from the low-pass filtered data enables us to investigate the essential dynamics of particle clusters in detail.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.385.2-385
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• 2002

Hermetic rotary compressor is one of the most important components for air conditioning system since it has a great effect on both the performance and the noise and vibration of the system. Noise and vibration of rotary compressor is occurred due to gas pulsation during compression process and unbalanced dynamic force. In order to reduce noise and vibration, it is necessary to identify sources of noise and vibration and effectively control them. (omitted)

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.9
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• pp.98-105
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• 1995

Recent microwave IC's reach to the extent of high operating frequencies at which bonding wires limit their performance as dominant parasitic components. Double bonding wires separated by an internal angle have been firstly characterized using the Method of Moments with the incorporation of the ohmic resistance calculated by the phenomenological loss equivalence method. For a 30$^{\circ}$ internal angle, the calculated total reactance is 45% less than that of a single bonding wire due to the negative mutual coupling effect. The radiation effect has been observed decreasing the mutual inductance, whereas for parallel bonding wires it greatly increases the mutual inductance. This calculation results can be widely used for designing and packaging of high frequency and high density MMIC's and OEIC's.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.235-242
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• 2000

The most important technology to improve crashworthiness of high speed trains is to design their front structures to absorb crash energy easily. In this paper, crashworthy designs of the front structures in KTX and KHST are compared by numerical simulation under SNCF accident scenario. Furthermore, to evaluate their crashworthiness tinder a typical real situation, the power cars are simulated for the accident collided against a deformable dump truck of 15 tons at 110 kph. The front structure of KHST, finally designed, shows a good crashworthy characteristics. Finally, the impact strength of coupling components is evaluated by analyzing a consist of the front three KHST units under scenario of train-to-train collision at 30 kph.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.170-174
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• 2006

In this paper electromagnetic topology (EMT) is used to analyze the lumped components on printed circuit boards (PCBs). It is difficult to obtain desirable results about the electromagnetic coupling problems by using a numerical or an experimental method on complex systems. The EMT can be considered as a helpful method to the analysis of electromagnetic interference / electromagnetic compatibility (EMI/EMC) problems in the complex system. To verify the validity of this method, three types of the PCBs mounting a simple circuit are fabricated and experimented.

• Ocean Systems Engineering
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• v.8 no.3
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• pp.281-312
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• 2018

Characteristics of a turbulence wind model control the magnitude and frequency distribution of wind loading on floating offshore wind turbines (FOWTs), and an in-depth understanding of how wind spectral characteristics affect the responses, and ultimately the design cost of system components, is in shortage in the offshore wind industry. Wind spectrum models as well as turbulence intensity curves recommended by the International Electrotechnical Commission (IEC) have characteristics derived from land-based sites, and have been widely adopted in offshore wind projects (in the absence of site-specific offshore data) without sufficient assessment of design implications. In this paper, effects of wind spectra and turbulence intensities on the strength or extreme responses of a 5 MW floating offshore wind turbine are investigated. The impact of different wind spectral parameters on the extreme blade loads, nacelle accelerations, towertop motions, towerbase loads, platform motions and accelerations, and mooring line tensions are presented and discussed. Results highlight the need to consider the appropriateness of a wind spectral model implemented in the strength design of FOWT structures.

• Journal of applied mathematics & informatics
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• v.27 no.5_6
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• pp.1343-1359
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• 2009

In this paper, we implement a relatively new analytical technique by combining the traditional variational iteration method and the decomposition method which is called as the variational decomposition method (VDM) for solving the sixth-order boundary value problems. The proposed technique is in fact the modification of variatioanal iteration method by coupling it with the so-called Adomian's polynomials. The analytical results of the equations have been obtained in terms of convergent series with easily computable components. Comparisons are made to verify the reliability and accuracy of the proposed algorithm. Several examples are given to check the efficiency of the proposed algorithm. We have also considered an example where the VDM is not reliable.