• Communications for Statistical Applications and Methods
• /
• v.15 no.5
• /
• pp.727-735
• /
• 2008

Consider a clinical trial in which the main end-point is survival. Suppose after the start of the study an intermediate event occurs which may be influenced by a covariate(or treatment). In many clinical studies the occurrence of an intermediate event may change the survival distribution. This investigation develops two-stage model which, in the first stage, models the effect of covariate on the intermediate event and models the relationship between survival time and covariate as well as the intermediate event. In this paper, the two-stage model is presented in order to model intermediate event and a test based on this model is also provided. A numerical simulations are carried out to evaluate its overall significance level.

• International Journal of Costume and Fashion
• /
• v.16 no.1
• /
• pp.55-70
• /
• 2016

The existing research on sustainability in the apparel industry provides no clear consensus on the definition of sustainability for the apparel brands and how sustainability of apparel brands as it is perceived by consumers can be measured. To fill this gap in research, the present study proposes and tests a confirmatory model of sustainability for apparel brands based on the three pillars of sustainability (i.e., economic, environmental, social sustainability) theorized in the Triple Bottom Line model. A survey of 754 U.S. consumers provided data for empirical testing. The results support the three-dimensional factor structure of sustainability for apparel brands and reveal that a second-order sustainability exerts a significant impact on both brand image and brand trust. The findings provide theoretical implications for researchers and practical managerial suggestions for marketers.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.4
• /
• pp.655-664
• /
• 2009

This paper, Part 1, describes the effective dual-input PSS parameter design procedure for the IEEE Type PSS2A against the Dangjin 612 MVA thermal plant's EX2000 excitation system. The suggested tuning technique used the model-based PSS tuning method and consisted of three steps: 1) generation system modeling; 2) determination of PSS2A model parameters using linear, time-domain transient and 3-phase simultaneous analyses, and 3) field testing and verification, which are described in Part 2. The effective PSS2A model parameters of EX2000 system in the Dangjin T/P #4 were designed according to the suggested procedure, and verified by using three analyses.

• Journal of Korean Society for Quality Management
• /
• v.36 no.1
• /
• pp.89-95
• /
• 2008

In this paper, we propose a software reliability growth model based on the superposition cause in the software system, which is isolated by the executed test cases in software testing. In particular, our model assumes an imperfect debugging environment in which new faults are introduced in the fault-correction process, and is formulated as a nonhomogeneous Poisson process(NHPP). Further, it is applied to fault-detection data, the results of software reliability assessment are shown, and comparison of goodness-of-fit with the existing software reliability growth model is performed.

• Journal of Welding and Joining
• /
• v.17 no.6
• /
• pp.100-107
• /
• 1999

In this paper, we deal with the speckle noise reduction and parameter estimation of ultrasonic NDT(non-destructive test) signals obtained during weld inspection of piping. The overall approach consists of three major steps, namely, speckle noise analysis, proposition of wavelet domain AR(autoregressive) model and flaw detection by proposed model parameter. The data are first processed whereby signals obtained using vertical and angle beam transducer. Correlation properties of speckle noise are then analyzed using multiresolution analysis in wavelet domain. The parameter estimation curve obtained using the proposed model is classified a flaw in weld region where is contaminated by severe speckle noise and also clear flaw signal is obtained through CA-CFAR threshold estimator that is a nonlinear post-processing method for removing the noise from reconstructed ultrasonic signal.

• Korean System Dynamics Review
• /
• v.15 no.3
• /
• pp.105-141
• /
• 2014

Human Resource Planning and Management(HRPM) is to make organization efficiently and effectively. Based on Promotion and Aging Chain Model, a revised personnel management prediction simulation is established in terms of mid- and long-term organizational changes, annual budget and personnel strategy including a promotion, aging and laying off for the best personnel architecture in organization. Also, the model is possible to find a solution for increasing the organizational capacity. An empirical application to quasi-governmental organization proceeded to testing and validating the model.

• International Commerce and Information Review
• /
• v.8 no.1
• /
• pp.33-50
• /
• 2006

This research develops, and empirically test a model for explaining/predicting the Determinants and Satisfaction of Portal Cite in Internet Initiation Page. Also this paper describes a theoretical model for investigating the service quality satisfaction in the Internet Initiation Page. This research is the first to empirical test the causal relationships in determinants of Portal Cite. The model of the satisfaction for Portal Cite are tested here using data from 224 samples. Based on the research model, a comprehensive set of hypotheses is formulated and a methodology for testing them is outlined. some of the hypotheses are tested empirically to demonstrate the applicability of the theoretical model. In examining the relationships of the determinants factors, satisfaction show in significantly by Convenience, Information Provided, Entertainments, Interaction but that show in not significantly by the Trustworthiness, In addition, Portal Cite in Internet Initiation Page shows indirect effect between customer satisfaction and referral.

• Smart Structures and Systems
• /
• v.15 no.2
• /
• pp.395-408
• /
• 2015

This study aims to propose a Bayesian approach to consider changes in temperature and vehicle weight as environmental and operational factors for vibration-based long-term bridge health monitoring. The Bayesian approach consists of three steps: step 1 is to identify damage-sensitive features from coefficients of the auto-regressive model utilizing bridge accelerations; step 2 is to perform a regression analysis of the damage-sensitive features to consider environmental and operational changes by means of the Bayesian regression; and step 3 is to make a decision on the bridge health condition based on residuals, differences between the observed and predicted damage-sensitive features, utilizing 95% confidence interval and the Bayesian hypothesis testing. Feasibility of the proposed approach is examined utilizing monitoring data on an in-service bridge recorded over a one-year period. Observations through the study demonstrated that the Bayesian regression considering environmental and operational changes led to more accurate results than that without considering environmental and operational changes. The Bayesian hypothesis testing utilizing data from the healthy bridge, the damage probability of the bridge was judged as no damage.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.37 no.2
• /
• pp.75-83
• /
• 2017

In this paper, we investigate the capacity of the lock-in infrared thermography technique for the evaluation of non-uniform top layers of a silicon carbide coating with a nickel based superalloy sample. The method utilized a multilayer heat transfer model to analyze the surface temperature response. The modelling of the sample was done in ANSYS. The sample consists of three layers, namely, the metal substrate, bond coat and top coat. A sinusoidal heating at different excitation frequencies was imposed upon the top layer of the sample according to the experimental procedures. The thermal response of the excited surface was recorded, and the phase angle image was computed by Fourier transform using the image processing software, MATLAB and Thermofit Pro. The correlation between the coating thickness and phase angle was established for each excitation frequency. The most appropriate excitation frequency was found to be 0.05 Hz. The method demonstrated potential in the evaluation of coating thickness and it was successfully applied to measure the non-uniform top layers ranging from 0.05 mm to 1 mm with an accuracy of 0.000002 mm to 0.045 mm.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.8
• /
• pp.1989-2009
• /
• 2013

How to discover router vulnerabilities effectively and automatically is a critical problem to ensure network and information security. Previous research on router security is mostly about the technology of exploiting known flaws of routers. Fuzzing is a famous automated vulnerability finding technology; however, traditional Fuzzing tools are designed for testing network applications or other software. These tools are not or partly not suitable for testing routers. This paper designs a framework of discovering router protocol vulnerabilities, and proposes a mathematical model Two-stage Fuzzing Test Cases Generator(TFTCG) that improves previous methods to generate test cases. We have developed a tool called RPFuzzer based on TFTCG. RPFuzzer monitors routers by sending normal packets, keeping watch on CPU utilization and checking system logs, which can detect DoS, router reboot and so on. RPFuzzer' debugger based on modified Dynamips, which can record register values when an exception occurs. Finally, we experiment on the SNMP protocol, find 8 vulnerabilities, of which there are five unreleased vulnerabilities. The experiment has proved the effectiveness of RPFuzzer.