• Journal of Communications and Networks
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• v.16 no.6
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• pp.583-591
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• 2014

In wireless communications, knowledge of the signal-to-noise ratio is required in diverse communication applications. In this paper, we derive the variance of the maximum likelihood estimator in the data-aided and non-data-aided schemes for determining the optimal shrinkage factor. The shrinkage factor is usually the constant that is multiplied by the unbiased estimate and it increases the bias slightly while considerably decreasing the variance so that the overall mean squared error decreases. The closed-form biased estimators for binary-phase-shift-keying and quadrature phase-shift-keying systems are then obtained. Simulation results show that the mean squared error of the proposed method is lower than that of the maximum likelihood method for low and moderate signal-to-noise ratio conditions.

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.103-109
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• 2007

The nonlinear characteristics of a suspension is directly related to the ride quality of a passenger car. In this study, the nonlinear characteristics of a spring and a damper of a passenger car is analyzed by dynamic experiments using the MTS single-axial testing machine. Also, a mathematical nonlinear dynamic model for the suspension is devised to estimate the ride quality using the K factor. And the effect on the variation of the parameters of the suspension is examined. The results showed that the dynamic viscosity of the oil in a damper was the parameter that most influeced the ride quality of a passenger car for the ride quality of a passenger car.

• Journal of the Korea Safety Management & Science
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• v.13 no.2
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• pp.115-127
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• 2011

The aim of this study was to develop a standard to estimate safety factors of corrugated fiberboard containers used for agricultural products. This study is limited to fresh agricultural products packaged in the corrugated fiberboard containers and further work needs to be done, but we believe the data and results obtained by this research will greatly help to set proper package design for boxes. Especially, safety factor would be practically helpful for researchers for future study and packaging users to save packaging costs.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.29-33
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• 2002

There are a lot of errors and little accuracy when calculating the grounding resistance with the transposition methods in the equivalent surface of hemisphere electrode. Therefore we should calculate the grounding resistance by using the mesh factor, In this paper, we would estimate the grounding value of mesh electrode with water tank model & estimation method using the reduced scale ratio of mesh electrode based on the theory of model electrode & proportional factor according to the reduced scale ratio. And also we have confirmed the accuracy of the empirical formula of model electrode by using the regression analysis.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1680-1681
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• 2007

This paper deals with RLS algorithm using Newton-Raphson method based adaptive forgetting factor for a passive telemetry RF sensor system in order to estimate the time variant parameter to be included in RF sensor model.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.04a
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• pp.319-324
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• 2006

In this paper, we propose Bayesian procedure for the multiple change points analysis in a sequence of fractions nonconforming. We first compute the Bayes factor for detecting the existence of no change, a single change or multiple changes. The Gibbs sampler with the Metropolis-Hastings subchain is run to estimate parameters of the change point model, once the number of change points is identified. Finally, we apply the results developed in this paper to both a real and simulated data.

• Journal of Applied Reliability
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• v.7 no.3
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• pp.127-136
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• 2007

The accelerated life tests(ALTs) and degradation characteristics of image intensifier assembly(KIT-7) under low illuminance and high temperature were investigated. The accelerated life tests were carried out at $5{\times}10^5\;fc-40^{\circ}C,\;10{\times}10^5\;fc-40^{\circ}C,\;5{\times}10^5\;fc-50^{\circ}C,\;10{\times}10^5\;fc-50^{\circ}C$ and relationship related to illuminance and temperature was used as an accelerated life test model. An ALTA program[6] was used to calculate an acceleration factor and the test of life distribution fit, and estimate three parameters of an life test model. To sum up, MTTF 10,000 h at $5{\times}10^{-5}\;fc-40^{\circ}C$ of image intensifier assembly was certificated.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.258-264
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• 2010

Most of fluid systems, such as P&ID in ships, power plants, and chemical plants, consist of various components. The components such as bends, tees, sudden-expansions, sudden-contractions, and orifices contribute to overall pressure loss of the system. The local pressure losses across such components are determined using a pressure loss coefficient, k-factor, in lumped parameter models. In many engineering problems Idelchik's k-factor models have been used to estimate them. The present work compares the k-factor based on CFD calculation against Idelchik's model in order to confirm whether a commercial CFD package can be used for pressure loss coefficient estimation of complex geometries. The results show that RSM is the best appropriate for evaluating pressure loss coefficient. Commercial CFD package can be used as a tool evaluating k-factor even though the accuracy is influenced by a turbulence model.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.5
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• pp.109-126
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• 2017

Universal soil loss equation (USLE) is used to estimate soil loss solely or employed in any hydrologic models. Since soil erosion has been an issue in South Korea for decades, the Ministry of Environment enacted a law to regulate soil erosion in 2012, which is the Notification of topsoil erosion status. The notification is composed of preliminary and field investigations, the preliminary investigation suggests to use USLE and provides USLE factors. However, the USLE factors provided in the notification was prepared at least 10 years ago, therefore it is limited to reflect recent climate changes. Moreover the current yearly USLE approach does not provide an opportunity to consider seasonal variation of soil erosion in South Korea. A GIS-based model was therefore applied to evaluate the yearly USLE approach in the notification. The GIS-based model employs USLE to estimate soil loss, providing an opportunity to estimate monthly soil loss with monthly USLE factor databases. Soil loss was compared in five watersheds, which were Geumgang, Hangang, Nakdonggang, Seomjingang, and Yeongsangang watersheds. The minimum difference was found at Seomjingang watershed, the yearly potential soil loss were 40.15 Mg/ha/yr by the notification approach and 34.42 Mg/ha/yr by the GIS-based model using monthly approach. And, the maximum difference was found at Nakdonggang watershed, the yearly potential soil loss were 27.01 Mg/ha/yr by the notification approach and 10.67 Mg/ha/yr by the GIS-based model using monthly approach. As a part of the study result, it was found that the potential soil loss can be overestimated in the notification approach.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.2
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• pp.120-126
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• 2005

We have proposed a characteristic method to estimate real composition when multi component oxide films are deposited by ALD. Final atomic concentration ratio was theoretically calculated from the film densities and growth rates for $HfO_2$ and $Al_2O_3$ using ALD processed HfxAhOz mms.W e have transformed initial source feeding ratio during deposition to fins] atomic ratio in $Hf_xAl_yO_z$ films through thickness factors ($R_{HFO_2}$ ami $R_{Al_2O_3}$) ami concentration factor(C) defined in our experiments. Initial source feeding ratio could be transformed into the thickness ratio by each thickness factor. Final atomic ratio was calculated from thickness ratio by concentration factor. It has been successfully confirmed that the predicted atomic ratio was in good agreement with the actual measured value by ICP-MS analysis.