• 대한전기학회논문지:시스템및제어부문D
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• 제52권5호
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• pp.193-193
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• 2003

This Paper analyses several model-order reduction methods and then proposes an improved n model and a new delay calculation method to be used in analyzing RC-class interconnects, which does not involve moment calculation processes. The proposed delay calculation method has been derived by combining the unproved $\pi$ model, the concept of effective capacitance and Elmore delay. This method has an advantage in that it can be applied in the calculation of end-to-end delay as well as incremental delay.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권5호
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• pp.193-200
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• 2003

This Paper analyses several model-order reduction methods and then proposes an improved n model and a new delay calculation method to be used in analyzing RC-class interconnects, which does not involve moment calculation processes. The proposed delay calculation method has been derived by combining the unproved $\pi$ model, the concept of effective capacitance and Elmore delay. This method has an advantage in that it can be applied in the calculation of end-to-end delay as well as incremental delay.

• Coupled systems mechanics
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• 제12권6호
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• pp.519-530
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• 2023

This paper presents a mathematical model suitable for the calculation of laminated glass, i.e. glass plates combined with an interlayer material. The model is based on a beam differential equation for each glass plate and a separate differential equation for the slip in the interlayer. In addition to slip, the model takes into account prestressing force in the interlayer. It is possible to combine the two contributions arbitrarily, which is important because the glass sheet fabrication process changes the stiffness of the interlayer in ways that are not easily predictable and could introduce prestressing of varying magnitude. The model is suitable for reformulation into an inverse procedure for calculation of the relevant parameters. Model consisting of a system of differential-algebraic equations, proved too stiff for cases with the thin interlayer. This novel approach covers the full range of possible stiffnesses of layered glass sheets, i.e., from zero to infinite stiffness of the interlayer. The comparison of numerical and experimental results contributes to the validation of the model.

• 한국컴퓨터정보학회논문지
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• 제26권12호
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• pp.11-18
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• 2021

본 논문에서는 함포 사격 정확도를 향상시키기 위해 표적 위치 예측과 사격 오차 도출에서의 딥러닝 알고리즘 적용 가능성을 연구하였다. 표적 위치 예측 시 딥러닝 알고리즘의 하나인 LSTM 모델과 RN 구조를 적용했을 때 좀 더 정밀한 표적 위치를 예측할 수 있다는 가능성을 확인하고 모델을 설계하였다. 사격 오차 도출 시 사격제원 계산에 영향을 끼치는 요소들을 데이터 셋으로 관리하며, GAN을 사용하여 데이터 셋을 생성 후 강화 학습을 진행하여 사격 오차를 줄일 수 있는 모델을 설계하였다. 2가지 모델을 결합하여 사격 정확도를 향상시키기 위한 딥러닝 기반의 사격제원 계산 모델을 설계하였다.

• Wind and Structures
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• 제38권6호
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• pp.445-459
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• 2024

To model the aeroelasticity in vortex-induced vibrations (VIV) of slender tubular towers, this paper presents an approach where the aerodynamic damping distribution along the height of the structure is calculated not only as a function of the normalized lateral oscillation but also considering the local incoming wind velocity ratio to the critical velocity (velocity ratio). The three-dimensionality of aerodynamic damping depending on the tower's displacement and the velocity ratio has been observed in recent studies. A contour map model of aerodynamic damping is generated based on the forced vibration tests. A sectional calculation procedure based on the spectral method is developed by defining the aerodynamic damping locally at each increment of height. The proposed contour map model of aerodynamic damping and the sectional calculation procedure are validated with full-scale measurement data sets of a rotorless wind turbine tower, where good agreement between the prediction and measured values is obtained. The prediction of cross-wind response of the wind turbine tower is performed over a range of wind speeds which allows the estimation of resulting fatigue damage. The proposed model gives more realistic prediction in comparison to the approach included in current standards.

• 한국의학물리학회지:의학물리
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• 제31권3호
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• pp.54-62
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• 2020

Dose calculation algorithms play an important role in radiation therapy and are even the basis for optimizing treatment plans, an important feature in the development of complex treatment technologies such as intensity-modulated radiation therapy. We reviewed the past and current status of dose calculation algorithms used in the treatment planning system for radiation therapy. The radiation-calculating dose calculation algorithm can be broadly classified into three main groups based on the mechanisms used: (1) factor-based, (2) model-based, and (3) principle-based. Factor-based algorithms are a type of empirical dose calculation that interpolates or extrapolates the dose in some basic measurements. Model-based algorithms, represented by the pencil beam convolution, analytical anisotropic, and collapse cone convolution algorithms, use a simplified physical process by using a convolution equation that convolutes the primary photon energy fluence with a kernel. Model-based algorithms allowing side scattering when beams are transmitted to the heterogeneous media provide more precise dose calculation results than correction-based algorithms. Principle-based algorithms, represented by Monte Carlo dose calculations, simulate all real physical processes involving beam particles during transportation; therefore, dose calculations are accurate but time consuming. For approximately 70 years, through the development of dose calculation algorithms and computing technology, the accuracy of dose calculation seems close to our clinical needs. Next-generation dose calculation algorithms are expected to include biologically equivalent doses or biologically effective doses, and doctors expect to be able to use them to improve the quality of treatment in the near future.

• Journal of Hydrospace Technology
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• 제1권1호
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• pp.41-56
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• 1995

Flew control devices, such as flow liners, are frequently introduced in a cavitation tunnel in order to reduce the tunnel blockage effect, when a three-dimensional wake distribution is simulated using a complete ship model or a dummy model. In order to estimate the tunnel wall effect and to evaluate the effect of flow liners on the simulated wake distribution, a surface panel method is adopted for the calculation of the flow around a ship model and flow liners installed in a rectangular test section off cavitation tunnel. Calculation results on the Sydney Express ship model show that the tunnel wall effect on the hull surface pressure distribution is negligible for less than 5% blockage and can be appreciable for more than 20% blockage. The flow liners accelerate the flow near the afterbody of the ship model, so that the pressure gradient there becomes more favorable and accordingly the boundary layer thickness would be reduced. Since the resulting wake distribution is assumed to resemble the full scale wake, flow liners can also be used to simulate an estimated full scale wake without modifying the ship model. Boundary taper calculation should be incorporated in order to correlate the calculated wake distribution with the measured one.

• Journal of Magnetics
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• 제19권4호
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• pp.378-384
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• 2014

Optimization design and robust design are significant measures for improving the performance and reliability of electromagnetic devices (EMDs, specifically refer to relays, contactors in this paper). However, the implementation of the above-mentioned design requires substantial calculation; consequently, on the premise of guaranteeing precision, how to improve the calculation speed is a problem that needs to be solved. This paper proposes a new method for establishing an approximate model for the EMD. It builds a relationship between the input and output of the EMD with different coil voltages and air gaps, by using a user-defined interpolating function. The coefficient of the fitting function is determined based on a quantum particle swarm optimization (QPSO) method. The effectiveness of the method proposed in this paper is verified by the electromagnetic force calculation results of an electromagnetic relay with permanent magnet.

• 한국재난관리표준학회지
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• 제1권3호
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• pp.83-91
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• 2008

최근 많은 건설정보가 전자문서로 기록되고 있다. 그러나 현재 실무에서 작성되고 있는 설계문서는 재난관리를 위한 정보의 공유나 교환에 적합하지 않다. 본 연구는 사회기반시설물의 구조계산서 정보를 체계적으로 저장 및 관리할 수 있도록 지원하기 위한 XML Schema 기반의 문서모델을 구축하는 방법을 제시하였다. 또한 구조계산서에 기술된 다양한 양식의 서술방식을 표현하기 위한 5가지의 기본 자료형을 개발하였다. 제시된 방법을 이용하여 강교량 구조계산서의 시범 문서모델을 구축하였으며, 이를 통해 제시된 방법이 구조계산서의 문서모델을 구축하는데에 효과적으로 사용가능 함을 확인할 수 있었다.

• 한국기계가공학회지
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• 제16권5호
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• pp.19-24
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• 2017

In this research, a practical stiffness calculation method is developed and applied for modifying the height of the headstock, turret, and tailstock of a CNC lathe to enlarge the turntable diameter. The casting structure is assumed to be a rigid body and the linear motion element to be an elastic spring to simplify the turret stiffness calculation model. The stiffness of the sliding guide and ball screw of the original lathe is measured with a push tester and LVDT sensor, and the turret stiffness of the modified lathe is predicted and compared with experimental results to verify the model. The measured stiffness of the original turret is $0.17kN/{\mu}m$ and that of the modified turret is $0.11kN/{\mu}m$, i.e., an 18% difference from the predicted result. The verified stiffness calculation model can be used to develop another modified lathe.