• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.824-828
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• 2007

In this paper Statistical Energy Analysis has been considered to predict middle, high frequency air borne interior noise. PIM method is used for verification. Damping loss factor and coupling loss factor have been derived from the response(SPL) of sub systems when the power is applied. The airborne SEA model of vehicle is modeled through AutoSea2. Insulation material's absorption coefficient and transmission loss are acquired from closed form solution and experiment.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.846-847
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• 2011

This paper presents the study on analysis of single phase induction motor characteristics by equivalent circuit. For high efficiency of single phase induction motor, the motor parameters used for equivalent circuit analysis is important. The accuracy of equivalent circuit analysis of motor depends on the circuit parameters like saturation factor. Therefore this paper proposed the analysis method considering saturation factor. The saturation factor was calculated by iteration routine and numerical method. this proposed method was verified by FEM analysis results and dynamo test results of the prototype model.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.383-386
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• 2009

Contract power conversion factor which is applied to estimate contract power of industrial customers is an important standard to calculate transformer capacity. This paper shows a reasonable contract power conversion factor, that was made by the systematic and statistical way considering actual conditions, such as investigated contract power and peak power for the last 5 years of each customer for industrial customers as to AMR system. In this dissertation, it is necessary to analyze the key features and general trend from the investigated data. It made an analysis of the feature parameters, such as average, standard deviation, median, maximum. minimum and thus it was carried the linear and nonlinear regression analysis. Therefore, this paper compared characteristics for a contract power conversion factor which is applied to calculate contract power with characteristics for a regression model for customers which maximum utilization factor of transformer is more than 60%.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.103-106
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• 2007

This paper presents single-phase SRM drive system with single-stage high power factor and low torque ripple. Single-phase SRM has simple mechanical and electrical structure, robust and high speed operation characteristic. But conventional SRM drive with diode bridge rectifier and filter capacitor has a low power factor because of short charge time of capacitor. Therefore, this paper presents a novel single-phase SRM drive with single-stage structure circuit, which can improve the power factor and reduce peak torque ripple. A novel switching topology is presented base on mathematical analysis. The novel drive method is verified by simulations and experiments.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3219-3226
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• 1994

A model is constructed to evaluate the stress intensity factors for a center crack subjected to polynomial anti-symmetric loading in a layered material. A Fredholm integral equation is derived by Fourier integral transform method. The integral equation is numerically analyzed to evaluate the effects of the ratios of shear modulus, Poisson's ratio and crack length to layer thickness as well as the number of layers on the stress intensity factor. The stress intensity factors are approached to constant values as the number of layers increase and decrease as the polynomial power of the loading increase. In case of the E-glass/Epoxy composite, dimensionless stress intensity factor is affected by cracked-resin layer thickness.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.164.1-164.1
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• 2011

Previously, many researchers assessed nearshore wave energy in two ways. The first is a simulation with respect to the offshore wave time series to validate the wave buoy data and the wave model results, and the other is to simulate the representative waves of typical seasonal wave conditions. The former requires enormous computational time and effort. The latter yields inspection on the patterns for the spatial and temporal distribution of nearshore wave energy but tends to underestimates the amount of wave energy in the nearshore region owing to the correlation between the significant wave height and wave period. $\ddot{O}$zger et al. (2004) derived the stochastic wave energy formulation by introducing a correction factor explicitly in terms of the covariance of the wave energy and significant wave height. In this study, a correction factor was applied for the assessment of nearshore wave energy obtained by numerical simulation of wave transformation with respect to representative waves.

• Journal of Korean Institute of Industrial Engineers
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• v.36 no.2
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• pp.108-116
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• 2010

The maintenance of a deteriorating system is often imperfect. Previous studies have shown that the imperfect preventive maintenance (PM) can reduce the wear out and aging effects of deteriorating systems to a certain level between the conditions of as good as new and as bad as old. In this paper, we employ the concept of the improvement factor in investigating two optimal PM policies; failure limit policy and periodic PM policy. We redefine the improvement factor model as a function of the cost of PM, using this concept, we derive the conditions of optimal PM policies and formulate expressions to compute the expected cost rate. Based on this information, the determination of the maintenance policies which minimize the cost rate is examined. Numerical examples for the Weibull distribution case are also given.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.1
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• pp.61-67
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• 1999

A watershed terrain factor is known to the very important in studies of a stream and a watershed. We have obtained the terrain factor in map directly or we have generated it in a digitalized map. In this study, DTED (Digital Terrain Elevation Data) offering in DMA(Defense Mapping Agency) was used to create a stream and a watershed and to extract the terrain factor. As comparison of the terrain factors gererated in digitalized map with the terrain factors extracted in DTED, DTED could be used to extract a terrain factor for a watershed management.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.12
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• pp.93-100
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• 2013

This paper propose a method to design the rotor of synchronous reluctance motors(SynRM) for maximum torque and power factor by using DOE(design of experiment) with the design variables which are parameters of barriers and segments. In this process, there are problems that require lots of simulation time and number of simulations when calculating the both torque and power factor using the finite element method in order to find load angle, core loss per speed. In order to improve this problem, we calculate only value of flux linkage by finite element method, and can decrease analysis and the number of analysis time by applying steady state expression of the power factor and torque. Finally, in order to verify the characteristics of optimal model, we make prototype motor and compare with the conventional SynRM. In this experiment, we use the DC current decay test for calculating d-and q-axis inductance.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.267-272
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• 1995

The objective of this study is to investigate the effect of concrete strength on the stirrup effectiveness factor(K) of reinforced concrete beams with stirrup based on previous test results(a/d$\geq$2.5). In the procedure of the estimation of K, it was assumed that the ultimate shear strength for beams without stirrup is equal to the concrete contribution to shear strength for beam with stirrup. A model equation for calculation the stirrup of compressive strength of concrete. It was shown that the stirrup effective factor of compressive strength of concrete. It wah shown that the stirrup effective factor is greater than 1.0 up to compressive strength 85MPa. Therefore the current ACI Code equation for predicting the shear strength and the stirrup effectiveness factor of 1.0 is conservative for nomal and high stength concrete beams with stirrup.