• International journal of advanced smart convergence
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• v.1 no.2
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• pp.16-19
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• 2012

A modified 4-coil magnetic resonance wireless power transfer (MRWPT) system is proposed. Four coils based on 2-coil system with additional two matching coils were used in this topology. When Tx-Rx distance is changed, the input impedance is changed. However, it can be adjusted by coil parameters of matching coils to maintain impedance matching for maximum efficiency. The equivalent circuit of MRWPT system was analyzed for both transmission function and optimum coupling coefficient of the matching coils. By using four spiral resonant coils, these design considerations was experimentally verified. The measured data agreed well with the calculated data and the transmission function of the proposed system was more efficient than that of conventional 2-coil system.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.200-207
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• 2001

This paper introduces a methodology of seismic fragility analysis and discusses the basic input variables, focusing on the conservatism and variability of reference response spectrum. The procedures to consider the composite modal damping in the seismic fragility analysis is presented and its effects on the seismic capacity of structure is evaluated through an example analysis of the nuclear power plant structure which has typical composite modal damping characteristics. Two seismic fragility analyses were performed to obtain the seismic capacities which evaluated by considering the composite modal damping and the single damping characteristics. The results showed that the seismic fragility analysis without considering the different values of composite modal damping may considerably overestimate the seismic capacity of coupled structures.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.2
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• pp.95-104
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• 2004

Leaks in underground pipelines can cause social, environmental and economical problems. One of relevant countermeasures against leaks is to find and repair of leak points of the pipes. Leak noise is a good source to identify the location of leak points of the pipelines. Although there have been several methods to detect the leak location with leak noise, such as listening rods, hydrophones or ground microphones, they have not been so efficient tools. In this paper, accelermeters aroused to detect leak locations which could provide an easier and more efficient method. Filtering, signal processing and algorithm of raw input data from sensors for the detection of leak location are described. A 120m-long and a 70m-long experimental pipeline systems are installed and the results with the systems show that the algorithm with the accelerometers offers accurate pinpointing for leaks location detection. Theoretical analysis of sound wave propagation speed of water in underground pipes, which is critically important in leak locating, is also described.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.260-264
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• 2003

It is possible to design the high performance, integration and low cost radio frequency components by using LTCC(Low Temperature Cofired Ceramic) technology. But there is a critical point to design the spiral inductor because of crosstalk effects. of the crosstalk effect of the spiral inductor are investigated using full-wave analysis of the FEM(Finite Element Method) in this paper. The results show that input power of the spiral inductor are coupled from 0.1% to 10% above 3GHz. Therefore, we should consider the crosstalk effects when we design the LTCC.

• Coupled systems mechanics
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• v.5 no.4
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• pp.371-393
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• 2016

We propose a heat jet approach for a two-dimensional square lattice with nearest neighbouring harmonic interaction. First, we design a two-way matching boundary condition that linearly relates the displacement and velocity at atoms near the boundary, and a suitable input in terms of given incoming wave modes. Then a phonon representation for finite temperature lattice motion is adopted. The proposed approach is simple and compact. Numerical tests validate the effectiveness of the boundary condition in reflection suppression for outgoing waves. It maintains target temperature for the lattice, with expected kinetic energy distribution and heat flux. Moreover, its linear nature facilitates reliable finite temperature atomic simulations with a correct description for non-thermal motions.

• 연구논문집
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• s.25
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• pp.67-76
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• 1995

A grid generation algorithm associated with turbomachinery cascade flow fields has been developed. The present grid generation system consists of four separate modules. The system input is made of the results of the preliminary design, i.e., flow-path, aerodynamic conditions along the spanwise direction, and the blade profile data. The grid generation method generates a series of two-dimensional grids in the blade-to-blade passage to build up the three-¬dimensional grid, The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The resultant grids generated from each module of the system are used as the preprocessor for the performance prediction of the turbomachinery blade using Naveir-Stokes method in addition to the blade surface modelling for CAD data. For purposes of illustration, the grid generation system is applied to several complex geometries inculding a turbine rotor with and without a tip flow grid. Application to the blade design of the LP compressor was demonstrated to be very reliable and practical in support of design activities. This customized system are coupled strongly with the design procedure and reduces the man-hours required to predict the aerodynamic performance of the turbomachinery cascades using the CFD technique.

• 한국전산유체공학회:학술대회논문집
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• 1997.10a
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• pp.38-42
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• 1997

A multiblock grid generation has been applied to a Navier-Stokes design procedure of a axial-flow compressors. A multiblock structure simplifies the creation of structured H-grids about complex turbomachinery geometries and facilitate the creation of a grid in the tip flow region. The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The input module is made of the results of the preliminary design, i.e., flow-path, aerodynamic conditions along the spanwise direction, and the blade profile data. The final grids generated from each module of the system are used as the preprocessor for the performance prediction of the sectional blade, the blade-stacking process and the three-dimensional flow simulation inside the blade passage. Application to the blade design of the LP compressor was demonstrated to be very reliable and practical in support of design activities. This customized system are coupled strongly with the design procedure of the turbomachinery cascades using the Navier-Stokes technique.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.5
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• pp.834-840
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• 2001

A real time multibody vehicle dynamics model has been developed and implemented using a subsystem synthesis method based on recursive formulation. To verify real time simulation capability the developed model has been applied to HMMWV(High Mobility Multipurpose Wheeled Vehicle) with steering system. For the kinematically driven steering system, the coupled front suspension-steering subsystem can be decoupled into two SLA suspension subsystems, which improves the efficiency of simulation. To investigate theoretical efficiency, operational counting method has been also employed to compare the proposed model with the conventional recursive dynamics model. Various simulations such as unsymmetric bump run, step steering(J-turn) and sine steering input test have been carried out to verify the real time feasibility of the proposed model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.369-373
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• 2001

In this paper, we proposes the steps adopted to construct the neural network model for GMAW welds. Conventional, automated process generally involves sophisticated sensing and control techniques applied to various processing parameters. Welding parameters are influenced by numerous factors, such as welding current, arc voltage, torch travel speed, electrode condition and shielding gas type and flow rate etc. In traditional work, the structural mathematical models have been used to represent this relationship. Contrary to the traditional model method, neural network models are based on non-parametric modeling techniques. For the welding process modeling, the non-linearity at well as the coupled input characteristics makes it apparent that the neural network is probably the most suitable candidate for this task. Finally, a suitable proposal to improve the construction of the model has also been presented in the paper.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.381-381
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• 2000

This paper describes the path planning method in an unknown environment for an autonomous mobile robot equipped with CCD(Charge-Coupled Device) camera. The mobile robot moves along the guideline. The CCD camera is useful to detect the existence of a guideline. The wavelet transform is used to find the edge of guideline. Using wavelet transform, we can make an image processing more easily and rapidly. We make a fuzzy control rule using image data then make a decision the position and the navigation of the mobile robot. The center value that indicates the center of guideline is the input of fuzzy logic controller and the steering angle of the mobile robot is the fuzzy output. Some actual experiments for the mobile robot applied fuzzy control show that the mobile robot effectively moves to target position.