• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.101-106
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• 1999

Fiber reinforced plastic composites is widely used to make be lightening of aircraft and automotive owing to having high specific strength and specific modulus. And it is very important to know a charge shape in order to have good products in the compression molding. In particular, the product such as a bumper beam is composed of the random and unidirectional composite mats. Its deformation and charge shape are very different by stack type of random and unidirectional mats. In this paper, the characteristics of flow fronts such as a bulging phenomenon for step-type random/unidirectional composite mats and slip parameters are studied numerically. And the effects of viscosity ratio and stack type on the mold filling parameters are also discussed.

• Journal of applied mathematics & informatics
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• 제16권1_2호
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• pp.307-321
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• 2004

In this paper, the unsteady Stokes problem is considered and also the pressure-correction method for the problem is described. At a fixed time level, we reduce the problem to two symmetric positive definite problems which depend on a time step parameter. Linear systems that arise from the problems are large, sparse, symmetric, positive definite and ill-conditioned as the time step tends to zero. Preconditioned problems based on an additive Schwarz method for solving the symmetric positive definite problems are derived and preconditioners are defined implicitly. It will be shown that the rate of convergence is independent of the mesh parameters as well as the time step size.

• Journal of Power Electronics
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• 제18권3호
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• pp.651-661
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• 2018

This paper suggests a new non-isolated high voltage gain DC-DC converter with two switches. The proposed two-switch converter has the following characteristics: a high voltage gain, a continuous input current with a small ripple, a reduction in the size of the inductor, and a simple circuit with only a few elements. A theoretical analysis, guidelines for parameter selection, and a comparison with conventional non-isolated high step-up converters are presented. A prototype of 250 W is set up to demonstrate the correctness of the proposed converter. Results obtained from simulations and experiments are presented.

• 전기의세계
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• 제26권1호
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• pp.87-90
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• 1977

Various simulation techniques were developed in the modeling of biological system during the last decades. Mostly analog and hybrid simulation techniques have been used. The authors chose the Digital Analog Simulation (DAS) technique by using the MIMIC language to simulate the saccadic eye movement system performances on the digital computer. There have been various models presented by many investigators after Young & Stark's sampled-data model. The eye movement model chosen by the authors is Robinson's model III which shows the parallel information processing characteristics clearly to the double-step input stimuli. In the process of simulation, the parameter and constants used were based on the neurophysiological data of the human and animals. The analog model blocks were converted to the corresponding MIMIC block diagrams and programmed into the MIMIC statements. The program was run on the CDC Cyber 72-14 computer. The essential input stimulus was double-step of 5 and 10 degrees, and target durations chosen were 50,100 and 150 msec. The results obtained by the DAS technqiue were in good agreement with analog simulation carried out by other investigators as well as with the experimental human saccadic eye movement responses to double-step target movements.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.500-500
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• 2000

In this paper, we deal wit,11 a simple tim varying feedforward compensator in order to decrease the amount of undershoots and overshoots on the step response. This compensator makes the step type input be a ramp input with saturation for 0 $\leq$ t < $\alpha$. It will be shown that the system with the feedforward compensator has small amount of undershoot and overshoot at the price of rise time. Also, provided the system properly stable, the influence of the design parameter $\alpha$ on the step response of the system with the feedforward compensator is investigated in the current paper.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.309-309
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• 2000

The main objective of this study is to understand the regeneration step of the PTSA(Pressure and thermal swing adsorption) process below the atmospheric pressure by rigorous dynamic simulation. This target process is to recover toluene using activated carbon as an adsorbent. To do this, the dynamic simulations for the regeneration step are performed at 360, 490, 590mmHg and at high temperature after the simulation of the adsorption step at latm and 298K. A mathematical model was developed to simulate the column dynamics of the adsorption systems. This model is based on non-equilibrium, non-isothermal and non-adiabatic conditions, and axial dispersion and heat conduction are also considered. Heat transfer resistances are considered in gas-solid, gas-column wall and column wall-outside air. The LDF(Linear Driving Force) approximation model describes the mass transfer rate between the gas and solid phase. This study shows that the recovery of toluene by PTSA is more preferable than that by general TSA.

• Journal of Power Electronics
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• 제16권3호
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• pp.915-924
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• 2016

A digital self-sustained phase shift modulation (DSSPSM) strategy that allows for good soft switching and dynamic response performance in the presence of step variations is presented in this paper. The working principle, soft switching characteristics, and voltage gain formulae of a LLC converter with DSSPSM have been provided separately. Furthermore, the method for realizing DSSPSM is proposed. Specifically, some key components of the proposed DSSPSM are carefully investigated, including a parameter variation analysis, the start-up process, and the zero-crossing capture of the resonant current. The simulation and experiment results verify the feasibility of the proposed control method. It is observed that the zero voltage switching of the switches and the zero current switching of the rectifier diodes can be easily realized in presence of step load variations.

• Journal of the Korean Data and Information Science Society
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• 제20권3호
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• pp.601-614
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• 2009

This paper derives noninformative priors for scale parameter of exponential distribution when the data are collected in multiple step stress accelerated life tests. We nd the objective priors for this model and show that the reference prior satisfies first order matching criterion. Also, we show that there exists no second order matching prior. Some simulation results are given and using artificial data, we perform Bayesian analysis for proposed priors.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제11B권2호
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• pp.28-33
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• 2001

The subject of this study is to improve the position performance of the linear motion for hybrid type Linear Pulse Motor (HLPM). Generally, there are two applicable methods to ensure precise position control ; a good processing method. This paper is suggested an electrical 125 microstep driving method so as to achieves the excellent control performance, besides the small mechanical manufacture of teeth pitch. The compensation method of digital PI control is apply to step response of stable position control, step error, vibration suppression and the approach to high stability, and the Ziegler-Nichols tuning method is applied to the proper design of control parameter. The proposed control method has been verified by simulation results of the suitable gain and phase margin of bode plot, and from experiment result of step response.

• 한국전자파학회논문지
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• 제18권11호
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• pp.1318-1326
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• 2007

본 논문에서는 waffle-iron 도파관 여파기의 실용적인 설계 방법을 기술하였다. 설계 과정은 두 단계로 이루어진다. 첫 단계로는 waffle-iron 구조의 단일 window에 대해 EM S/W tool를 이용하여 S-파라미터를 구하고, ABCD 파라미터로 변환하여 K-인버터를 계산하고, 두 번째 단계는 분포 정수 원형 여파기와 일치되게 window의 크기를 최적화한다. 설계 방법을 검증하기 위해 위성통신용 Ka 대역 여파기를 설계하고 제작하였다. 측정 결과는 계산 결과와 비교하여 양호하게 일치하였다.