• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.957-966
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• 2020

This paper presents the virtual mass method to implement the prediction of total resistance for ice-going ship in floe ice region based on the combined method of CFD and DEM. Two ways of floe ice distribution are adopted for the analysis and comparison. The synthetic ice model test has been conducted to determine the optimal virtual mass coefficients for the two different floe ice distributions. Moreover, the further verification and prediction are developed in different ice conditions. The results show that, the fixed and random distributions in numerical method can simulate the interaction of ship and ice vividly, the trend of total resistance varying with the speed and ice concentration obtained by the numerical simulation is consistent with the model test. The random distribution of floe ice has higher similarity and better accuracy than fixed distribution.

• Journal of the Korea Institute of Building Construction
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• v.5 no.1 s.15
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• pp.53-61
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• 2005

The purpose of this study presents useful data on the choice or development of floor covering from slip viewpoint by examining closely the impact of the changes in sliding experiments due to the wear of floor covering by walk. The result of wear practical test per ten thousand walks enforces some kind of popular floor covering and measure of coefficient of slip resistance as follows: (1) When surface of floor covering is in the state of wet, the degree of wear doesn't affect greatly in slip. (2) When surface of floor covering is in dry and clean state, most floor coverings have the tendency to lower the coefficient of slip resistance with the amount of walk on it. (3) Change in the tendency of slip resistance by wear appeared mainly due to the differences in the state of floor covering and organic floor covering appeared to have great reduction of coefficient of slip resistance than the inorganic ones. (4) According to the result of investigation on changes in tendency of coefficient of slip resistance due to the increase in the number of walk and if two hundred thousand walks were done, regardless of surface shape or kind of site, etc, the safety of floor covering, in slip viewpoint, greatly reduces.

• Electrical & Electronic Materials
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• v.8 no.5
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• pp.626-632
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• 1995

In this paper, The effect of the impedances in SNOSFET's memory devices has been developed. The effect of source and drain impedances measured by means of two bias resistances - field effect bias resistance by inner region, external bias resistance. The effect of the impedances by source and drain resistance shows the dependence of the function of voltages applied to the gate. It shows the differences of change in source drain voltage by means of low conductance state and high conductance state. It shows the delay of threshold voltages. The delay time of low conductance state and high conductance state by the impedances effect shows 3[.mu.sec] and 1[.mu.sec] respectively.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.07a
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• pp.35-52
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• 1999

This paper addresses on new codes of practice, limit state design; load resistance factored design and Eurocode 7, which have recently been adopted by foundation engineers in North America and European Communities. A brief description of the limit state design concepts and some introductions to Australia and Sweden national code for pile foundation are made on behalf of pile capacity determination. Also, simple closed form solution for rational resistance factor when resistance is log-normally distributed, has been derived for pile foundation.

• Geomechanics and Engineering
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• v.15 no.3
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• pp.879-888
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• 2018

Probability-based design codes have been developed to sufficiently confirm the safety level of structures. One of the most acceptable probability-based approaches is Load Resistance Factor Design (LRFD), which measures the safety level of the structures in terms of the reliability index. The main contribution of this paper is to calibrate the load and resistance factors of the design code for tunnels. The load and resistance factors are calculated using the available statistical models and probability-based procedures. The major steps include selection of representative structures, consideration of the limit state functions, calculation of reliability for the selected structures, selection of the target reliability index and calculation of load factors and resistance factors. The load and resistance models are reviewed. Statistical models of resistance (load carrying capacity) are summarized for strength limit state in bending, shear and compression. The reliability indices are calculated for several segments of a selected circular tunnel designed according to the tunnel manual report (Tunnel Manual). The novelty of this paper is the selection of the target reliability. In doing so, the uniform spectrum of reliability indices is proposed based on the probability paper. The final recommendation is proposed based on the closeness to the target reliability index.

• Corrosion Science and Technology
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• v.10 no.4
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• pp.125-130
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• 2011

This study was performed to improve the corrosion resistance and the stability of passive film on copper tube by potentiostatic polarization method in synthetic tap water. Formation of passive film was carried out by anodic potentiostatic polarization at various passivation potentials and passivation times in 0.1 M NaOH solution. Stability of passive film and corrosion resistance was evaluated by self-activation time, ${\tau}_0$ from passive state to active state on open-circuit state in 0.1 M NaOH solution. Addition of polyphosphate in NaOH solution prolonged the self-activation time and improved the corrosion resistance, and the addition of 5 ppm polyphosphate was most effective. It was also observed that better corrosion resistance was obtained by potentiostatic polarization at 1.0 V (vs. SCE) than at any other passivation potentials. Passivated copper tube showed perfect corrosion resistance for the immersion test in synthetic tap water showing that the anodic potentiostatic polarization treatment in 0.1 M NaOH with 5 ppm polyphosphate solution would be effective in improving the corrosion resistance and preventing the blue water problem.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1332-1342
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• 2014

This paper proposes a novel test circuit for SiC transistors. On-state resistance under practical application conditions is an important characteristic for the device reliability and conduction efficiency of SiC transistors. In order to measure the on-state resistance in practical applications, high voltage is needed, and high current is also necessary to ignite performance for the devices. A soft-switching circuit based on synchronous buck topology is developed in this paper. To provide high-voltage and high-current stresses for the devices without additional spikes and oscillations, a resonant circuit has been introduced. Using the novel circuit technology, soft-switching can be successfully realized for all the switches. Furthermore, in order to achieve accurate measurement of on-state resistance under switching operations, an active clamp circuit is employed. Operation principle and design analysis of the circuit are discussed. The dynamic measurement method is illustrated in detail. Simulation and experiments were carried out to verify the feasibility of the circuit. A special test circuit has been developed and built. Experimental results confirm that the proposed circuit gives a good insight of the devices performance in real applications.

• Steel and Composite Structures
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• v.47 no.1
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• pp.103-117
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• 2023

This paper presents an investigation on the shear resistance of corrugated web steel beams (CWBs) with a circular web opening. A total of five specimens with different diameters of web openings were designed and tested with vertical load applied on the top flange at mid-span. The ultimate strengths, failure modes, and load versus middle displacement curves were obtained from the tests. Following the tests, numerical models of the CWBs were developed and validated against the test results. The influence of the web plate thickness, steel grade, opening diameter, and location on the shear strength of the CWBs was extensively investigated. An XGBoost machine learning model for shear resistance prediction was trained based on 256 CWB samples. The XGBoost model with optimal hyperparameters showed excellent accuracy and exceeded the accuracy of the available design equations. The effects of geometric parameters and material properties on the shear resistance were evaluated using the SHAP method.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.50-52
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• 2006

This paper Proposes a new method of on-line estimation for rotor resistance of the induction motor in the indirect vector controlled drive, using artificial neural network (ANN). The back propagation algorithm is used for training of the neural networks. The error between the desired state variable of an induction motor and actual state variable of a neural network model is back propagated to adjust the weight of a neural network model, so that the actual state variable tracks the desired value. The performance of rotor resistance estimator and torque and flux responses of drive, together with these estimators, are investigated variations rotor resistance from their nominal values. The rotor resistance are estimated analytically, using the proposed ANN in a vector controlled induction motor drive.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.5
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• pp.503-507
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• 2014

The on-state resistance ($R_{ON}$) instability of standard complementary metal-oxide-semiconductor (CMOS) antifuse cells has been observed for the first time by using acceleration factors: stress current and ambient temperature. If the program current is limited, the $R_{ON}$ increases as time passes during read operation.