• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1846-1851
• /
• 2003

Approximate optimization has become popular in engineering field such as MDO and Crash analysis which is time consuming. To accomplish efficient approximate optimization, accuracy of approximate model is very important. As surrogate model, Kriging have been widely used approximating highly nonlinear system . Because Kriging employs interpolation method, it is adequate for deterministic computer simulation. Because there are no random errors and measurement errors in deterministic computer simulation, instead of classical DOE ,space filling experiment design which fills uniformly design space should be applied. In this work, various space filling designs such as maximin distance design, maximum entropy design are reviewed. And new design improving maximum entropy design is suggested and compared.

• Journal of the Korean Data and Information Science Society
• /
• v.16 no.1
• /
• pp.41-50
• /
• 2005

The various methods have been studied to develop discriminant model for pregnancy induced hypertension(PIH) as high risk pregnant. In this study, we adapt the approximate entropy which is the non-linear chaotic measuring method. Then, we develop a system to discriminant PIH pregnant using QUEST with S-PLUS.

• Communications for Statistical Applications and Methods
• /
• v.27 no.4
• /
• pp.469-486
• /
• 2020

Entropy is an important term in statistical mechanics that was originally defined in the second law of thermodynamics. In this paper, we consider the maximum likelihood estimation (MLE), maximum product spacings estimation (MPSE) and Bayesian estimation of the entropy of an inverse Weibull distribution (InW) under a generalized type I progressive hybrid censoring scheme (GePH). The MLE and MPSE of the entropy cannot be obtained in closed form; therefore, we propose using the Newton-Raphson algorithm to solve it. Further, the Bayesian estimators for the entropy of InW based on squared error loss function (SqL), precautionary loss function (PrL), general entropy loss function (GeL) and linex loss function (LiL) are derived. In addition, we derive the Lindley's approximate method (LiA) of the Bayesian estimates. Monte Carlo simulations are conducted to compare the results among MLE, MPSE, and Bayesian estimators. A real data set based on the GePH is also analyzed for illustrative purposes.

• Journal of the Korean Data and Information Science Society
• /
• v.13 no.2
• /
• pp.77-85
• /
• 2002

The statistical testing methods have been widely recognized to determine the plain and cipher texts. In fact, the randomness for a sequence from an encryption algorithm is necessary to guarantee security and reliance of cipher algorithm. Thus, the statistical randomness tests are used to discover cipher text. In this paper, we would provide the critical value for an approximate entropy test by estimating the nonlinear regression equation when the number of sequence and the level of significance are given. Thus, we can discern plan and cipher text for real problem with given number of sequence and the level of significance. Also, we confirm the fitness of the estimated critical values from the rate of success for plain or cipher text.

• 한국데이터정보과학회:학술대회논문집
• /
• 2004.04a
• /
• pp.141-149
• /
• 2004

The various methods have been studied to develop discriminant model for Pregnancy Induced Hypertension(PIH) as high risk pregnant. In this study, we adapt the approximate entropy which is the non-linear chaotic measuring method. Then, we develop the system to discriminant PIH pregnant using QUEST with S-PLUS.

• Communications for Statistical Applications and Methods
• /
• v.13 no.1
• /
• pp.73-88
• /
• 2006

In this paper, we construct data-base for fetal heart rate (FHR) data and develop the FHR Monitering system to diagnose fetus, HYFM-III. For diagnostic system, a few statistical decision making mechanism are adopted, such as approximate entropy, neural networks, and logistic discrimination. Since FHR data is very chaotic, we mostly adopt nonlinear statistical methods. On the basis of this system, we expect to develop expert system for early detection of abnormal fetus.

• Journal of the Korean Data and Information Science Society
• /
• v.28 no.3
• /
• pp.659-668
• /
• 2017

The inverse Weibull distribution (IWD) can be readily applied to a wide range of situations including applications in medicines, reliability and ecology. It is generally known that the lifetimes of test items may not be recorded exactly. In this paper, therefore, we consider the maximum likelihood estimation (MLE) and Bayes estimation of the entropy of a IWD under generalized progressive hybrid censoring (GPHC) scheme. It is observed that the MLE of the entropy cannot be obtained in closed form, so we have to solve two non-linear equations simultaneously. Further, the Bayes estimators for the entropy of IWD based on squared error loss function (SELF), precautionary loss function (PLF), and linex loss function (LLF) are derived. Since the Bayes estimators cannot be obtained in closed form, we derive the Bayes estimates by revoking the Tierney and Kadane approximate method. We carried out Monte Carlo simulations to compare the classical and Bayes estimators. In addition, two real data sets based on GPHC scheme have been also analysed for illustrative purposes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.760-763
• /
• 2007

We studied how linear and nonlinear heart rate dynamics differ between normal fetuses and uncomplicated small-forgestational age (SGA) fetuses, aged 32-40 weeks' gestation. We analyzed each fetal heart rate time series for 20 min and quantified the complexity (nonlinear dynamics) of each fetal heart rate (FHR) time series by approximate entropy (ApEn) and correlation dimension (CD). The linear dynamics were analyzed by canonical correlation analysis (CCA). The ApEn and CD of the uncomplicated SGA fetuses were significantly lower than that of the normal fetuses in all three gestational periods (32-34, 35-37, 38-40 weeks). Canonical correlation ensemble in SGA fetuses is slightly higher than normal ones in all three gestational periods, especially at 35-37 weeks. Irregularity and complexity of the heart rate dynamics of SGA fetuses are lower than that of normal ones. Also, canonical ensemble in SGA fetuses is higher than in normal ones, suggesting that the FHR control system has multiple complex interactions. Along with the clear difference between the two groups' non-linear chaotic dynamics in FHR patterns, we clarified the hidden subtle differences in linearity (e.g. canonical ensemble). The decrease in non-linear dynamics may contribute to the increase in linear dynamics. The present statistical methodology can be readily and routinely utilized in Obstetrics and Gynecologic fields.

• Korean Journal of Applied Biomechanics
• /
• v.26 no.3
• /
• pp.257-264
• /
• 2016

Objective: The purpose of this study was to determine the periodicity of shank-foot segment coupling and free torque before and after fatigue induced by prolonged running. Method: Fifteen young healthy male participants with a rear-foot strike ran on instrumented dual-belt treadmills at 70% of their maximum oxygen uptake for 65 min. Kinematic and ground reaction force data were collected for 20 continuous strides at 5 and 65 min (considered the fatigued condition). The approximate entropy tool was applied to assess the periodicity of the shank internal-external rotation, foot inversion-eversion, shank-foot segment coupling, and free torque for the two running conditions. Results: The periodicity of all studied parameters, except foot inversion-eversion, decreased after 65 min of running (fatigued condition) for 80% of the participants in this study. Furthermore, 60% of the participants showed similarities in the change of periodicity pattern in shank internal-external rotation, coupling, and free torque. Conclusion: The findings indicated that the foot inversion-eversion motion may pose a higher risk of injury than the shank internal-external rotation, coupling, and free torque in the fatigued condition during prolonged running.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.15 no.5
• /
• pp.69-74
• /
• 2015

In this paper the patterns of information system is reduced so that control rules can guarantee fast response of queries in database. Generally an information system includes many kinds of necessary and unnecessary attribute. In particular, inconsistent information system is less likely to acquire the accuracy of response. Hence we are interested in the simple and understandable rules that can represent useful patterns by means of rough entropy and Bayesian posterior probability. We propose an algorithm which can reduce control rules to a minimum without inadequate patterns such that the implication between condition attributes and decision attributes is measured through the framework of rough entropy. Subsequently the validation of the proposed algorithm is showed through test information system of new employees appointment.