• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1049-1052
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• 1998

A new simplified circuit model for the switching noise analysis of the complicated multi-layer IC package is developed. The current flowing mechanism on the ground and power planes of the package is simplified by using the dependent current soures and partial plane circuit model. The methodology is very cost-efficient as well as accurate. It is demonstrated that the nosie based on the simplified circuit model has an excellent agreement with that of the complicated full circuit model. However, the simplified model takes only 5 minutes for the switching noise simulation, while the full circuit model takes more than 4 hours.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.1 no.1
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• pp.20-27
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• 1990

This paper presents an efficient method to estimate the induced current by the external electromagnetic wave when the line system is composed of cascaded transmission lines. To solve this phenomena, we apply the state variable method to the nonhomogeneous differential equation. This new method is the way of transferring the sources at a different point by the Ch- aracteristics of the transition matrix. Using this method, we investigate the characteristics of the induced power of the transmission line above the perfectly conducting ground plane.

• Journal of the Earthquake Engineering Society of Korea
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• v.25 no.3
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• pp.111-119
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• 2021

A shear wall is a structural member designed to effectively resist in-plane lateral forces, such as strong winds and earthquakes. Due to its efficiency and stability, shear walls are often installed in residential buildings and essential facilities such as nuclear power plants. In this research, to predict the results of the shaking table test of the three-story shear wall RC structure hosted by the Korea Atomic Energy Research Institute, three types of numerical modeling techniques are proposed: Preliminary, Calibrated 1, and Calibrated 2 models, in order of improvement. For the proposed models, an earthquake of the 2016 Gyeongju, South Korea (peak ground acceleration of 0.28 g) and its amplified earthquake (peak ground acceleration of 0.50 g) are input. The response spectra of the measuring points are obtained by numerical analysis. Good agreement is observed in the comparisons between the experiment results and the simulation conducted on the finally adopted numerical model, Calibrated 2. In the process of improving the model, this paper investigates the influences of the mode shape, material properties, and boundary conditions on the structure's seismic behavior.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2052-2058
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• 2009

As the operating frequency of digital system increases and voltage swing decreases, an accurate and high speed analysis of PCB board becomes very important. Transmission matrix method, which use the multiple products of unit column matrix, is the highest speedy method in PCB board analysis. In this paper a new method to reduce the calculation time of PCB board impedances is proposed. First, in this method the eigenvalue and eigenvectors of the transmission matrix for unit column of PCB are calculated and the transmission matrix for the unit column is transformed using similarity transform to reduce the number of multiplication on the matrix elements. This method using the similarity transform can reduce the calculation time greatly comparing the previous method. The proposed method is applied to the 1.3 inch by 1.9 inch board and shows about 10 times reduction of calculation time. This method can be applied to the PCB design which needs a lots of repetitive calculation of board impedances.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.5
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• pp.439-446
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• 2016

The characteristics of bearingless main rotor of helicopter are investigated through non-rotating tests and rotating tests. The stiffness and natural frequencies of rotor blades, flexbeam, and torque tube which are core components of baearingless rotor are measured to obtain input material properties for rotor analysis. The functional test on ground for assembly of one hub with damper, snubber, and no blade is carried out to check interfaces between components, kinematics of components, and pitch motion ranges under applied loads including centrifugal load. The 4-bladed bearingless rotor with 5.82m of rotor radius is tested on the whirl tower with rotation plane of 9.65m height. The thrust and power are measured to obtain hover performance and the frequencies and dampings of the rotor are obtained by excitation of cyclic pitch by hydraulic actuators.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.25-32
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• 2021

In this study, it proposes a mode converter that is relatively easy to implement and can shorten the transmission line length of the final combining port and it was fabricated and tested by applying it to an 8-way spatial combiner. The proposed mode converter converts the signal converted from the doorknob-shaped circular disk connected to the ground into the TM₀₁ mode by opening it in the circular waveguide. The 8-way waveguide spatial combiner is designed and implemented so that 8 signals input from the H-plane are combined in a circular waveguide at the center, and the final combining mode is TM₀₁. The test results confirmed excellent performance with an insertion loss of less than 0.4dB and a combining efficiency of 95% or more. In addition, it was confirmed that it is suitable for high output by calculating the breakdown voltage and discharge threshold power of the new mode conversion structure through electric field analysis. The results confirmed through this study are expected to be applicable to high-power, high-efficiency SSPA in various fields in the future.

• Korean Journal of Remote Sensing
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• v.35 no.6_1
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• pp.933-944
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• 2019

This study analyzes the tide deformation of land boundary regions on the east (Region A) and west (Region B) sides of the Ross Ice Shelf in Antarctica using Double-Differential Interferometric Synthetic Aperture Radar (DDInSAR). A total of seven Sentinel-1A SAR images acquired in 2015-2016 were used to estimate the accuracy of tide prediction model and Young's modulus of ice shelf. First, we compared the Ross Sea Height-based Tidal Inverse (Ross_Inv) model, which is a representative tide prediction model for the Antarctic Ross Sea, with the tide deformation of the ice shelf extracted from the DDInSAR image. The accuracy was analyzed as 3.86 cm in the east region of Ross Ice Shelf and it was confirmed that the inverse barometric pressure effect must be corrected in the tide model. However, in the east, it is confirmed that the tide model may be inaccurate because a large error occurs even after correction of the atmospheric effect. In addition, the Young's modulus of the ice was calculated on the basis of the one-dimensional elastic beam model showing the correlation between the width of the hinge zone where the tide strain occurs and the ice thickness. For this purpose, the grounding line is defined as the line where the displacement caused by the tide appears in the DDInSAR image, and the hinge line is defined as the line to have the local maximum/minimum deformation, and the hinge zone as the area between the two lines. According to the one-dimensional elastic beam model assuming a semi-infinite plane, the width of the hinge region is directly proportional to the 0.75 power of the ice thickness. The width of the hinge zone was measured in the area where the ground line and the hinge line were close to the straight line shown in DDInSAR. The linear regression analysis with the 0.75 power of BEDMAP2 ice thickness estimated the Young's modulus of 1.77±0.73 GPa in the east and west of the Ross Ice Shelf. In this way, more accurate Young's modulus can be estimated by accumulating Sentinel-1 images in the future.