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Citation - WoS: 6
Citation - Scopus: 10
Male and Female Differences in the Use of Social Media for Learning Purposes
(Routledge Journals, Taylor & Francis Ltd, 2018) Akman, Ibrahim; Turhan, Cigdem
This study aims to explore the differences between male and female users' behaviour with regard to acceptance of social media for learning in higher educational institutions. For this purpose, a survey was conducted and the least square regression analysis approach was utilised to investigate the relationships among the constructs in the research model for male and female users from a general and ethical perspective, focusing on the reliability, performance and awareness factors. The findings from the analysis reveal that a significant degree of diversity is present in the factors represented by general reliability', ethical reliability', ethical performance', ethical awareness' and ethical intention'.
Citation - WoS: 27
Citation - Scopus: 31
Generalized Extreme Shock Models and Their Applications
(Taylor & Francis inc, 2020) Bozbulut, Ali Riza; Eryilmaz, Serkan
In the classical extreme shock model, the system fails due to a single catastrophic shock. In this paper, by assuming different arrival patterns of the shocks, two new types of extreme shock models are introduced. In these models, m possible sources may exert shocks on the system. Both models reduce to the classical extreme shock model when m = 1. Assuming phase-type distribution for times between successive shocks, we obtain survival functions and mean time to failure values of the system under new models. Two different optimization problems are also considered to determine the optimal number of sources.
Citation - WoS: 8
Citation - Scopus: 10
Computing Reliability Indices of a Wind Power System Via Markov Chain Modelling of Wind Speed
(Sage Publications Ltd, 2024) Eryilmaz, Serkan; Bulanik, Irem; Devrim, Yilser
Statistical modelling of wind speed is of great importance in the evaluation of wind farm performance and power production. Various models have been proposed in the literature depending on the corresponding time scale. For hourly observed wind speed data, the dependence among successive wind speed values is inevitable. Such a dependence has been well modelled by Markov chains. In this paper, the use of Markov chains for modelling wind speed data is discussed in the context of the previously proposed likelihood ratio test. The main steps for Markov chain based modelling methodology of wind speed are presented and the limiting distribution of the Markov chain is utilized to compute wind speed probabilities. The computational formulas for reliability indices of a wind farm consisting of a specified number of wind turbines are presented through the limiting distribution of a Markov chain. A case study that is based on real data set is also presented.
Citation - WoS: 13
Citation - Scopus: 14
On Mean Residual Life of Discrete Time Multi-State Systems
(Nctu-national Chiao Tung Univ Press, 2013) Eryilmaz, Serkan
The mean residual life function is an important characteristic in reliability and survival analysis. Although many papers have studied the mean residual life of binary systems, the study of this characteristic for multi-state systems is new. In this paper, we study mean residual life of discrete time multi-state systems that have M + 1 states of working efficiency. In particular, we consider two different definitions of mean residual life function and evaluate them assuming that the degradation in multi-state system follows a Markov process.
Citation - WoS: 19
Citation - Scopus: 21
Psychometric Properties of a Turkish Version of the Oral Health Impact Profile-14
(Wolters Kluwer Medknow Publications, 2017) Balci, N.; Alkan, N.; Gurgan, C. A.
Objectives: The purpose of this study was to analyze and evaluate a Turkish translation of the oral health impact profile-14 (OHIP-14) in a Turkish population to provide an objective standard for future studies. Methods: This cross-sectional research study consisted of three independent studies. Data were collected utilizing a personal interview and a review of periodontal records. This study was performed on 1205 subjects who were visiting for routine medical check-ups. The OHIP-14 was administered to measure oral health related to the quality of life, along with a questionnaire addressing demographic information, such as age, gender, and education. Results: The reliability coefficient (Cronbach's alpha) of the Turkish version OHIP-14-TR (OHIP-14-TR) was reported to be nearly perfect in all 3 parts of our study (alpha 1: 0.82; alpha 2: 0.76; alpha 3: 0.91); additionally, values were greater than the recommended 0.70 threshold. Spearman's correlation coefficients showed that both OHIP scores significantly correlated with periodontal parameters, serving as proof of convergent validity (P < 0.01, P < 0.001). The principal component analysis with varimax rotation revealed seven factors. The OHIP-14-TR was more than 95% comprehensible. Conclusion: The OHIP-14-TR is a reliable, valid, and comprehensible scale for measuring oral health-related quality of life in the Turkish population.
Citation - WoS: 7
Citation - Scopus: 8
Analysis of the Two-Unit Cold Standby Repairable System With Damage and Repair Time Dependency Via Matrix-Exponential Distributions
(Taylor & Francis Ltd, 2021) Kus, Coskun; Eryilmaz, Serkan
In this paper, two-unit standby repairable system is studied via matrix-exponential distributions. The system under concern consists of one active and one standby components, and fails if either a damage size upon the failure of the active component is larger than a repair limit or the repair time of the failed unit exceeds the lifetime of the active unit, whichever happens first. Under the assumption that the damage size and repair time are statistically dependent, the Laplace transform of the system's lifetime is obtained. The Laplace transform is shown to be rational under particular cases, and the reliability evaluation of the system is performed via well-known distributional properties of the matrix-exponential distributions. The problem of estimating the unknown parameters of the operation time and repair time distributions is also discussed based on system's lifetime data.
Citation - WoS: 4
Citation - Scopus: 4
Development and Psychometric Analysis of a Pediatric Oncology Nurses' Educational Needs Scale
(Wiley, 2023) Kudubes, Asli Akdeniz; Semerci, Remziye; Ozbay, Sevil Cinar; Ay, Ayse; Boztepe, Handan
Background/objectivesIt is important to determine the educational needs of pediatric oncology nurses in order to maximize and implement nursing care interventions. Therefore, this study aims to develop a valid and reliable measurement tool to determine pediatric oncology nurses' educational needs and examine its psychometric properties. Design/methodsThis methodological study was conducted with 215 pediatric oncology nurses in Turkey between December 2021 and July 2022. Data were collected with the "Nurse Information Form" and "Pediatric Oncology Nurses' Educational Needs Scale." IBM SPSS 21.0 and IBM AMOS 25.0 software programs were used for data analysis, and descriptive statistics were used to analyze numeric variables. Exploration and confirmatory factor analyses were performed to determine the scale's factorial structure. ResultsThe factorial analysis was used to test the structural validity of the scale. A five-factor structure consisting of 42 items was developed. The Cronbach's alpha coefficient for "Illness" was .978, "Chemotherapy and Side Effect" was .978, "Another Therapy and Side Effect" was .974, "Palliative Care" was .967, "Supportive Care" was .985, and the total score was .990. Fit indices resulting from the study were chi(2)/SD: 3.961, root mean square error of approximation (RMSEA): 0.072, goodness-of-fit index (GFI): 0.95, comparative-of-fit index (CFI): 0.96, and normed fit index (NFI): 0.95. ConclusionThe Pediatric Oncology Nurses' Educational Needs Scale is a valid and reliable scale for pediatric oncology nurses to determine their educational needs.
Citation - WoS: 12
Citation - Scopus: 14
The Markov Discrete Time Δ-Shock Reliability Model and a Waiting Time Problem
(Wiley, 2022) Chadjiconstantinidis, Stathis; Eryilmaz, Serkan
delta-shock model is one of the widely studied shock models in reliability theory and applied probability. In this model, the system fails due to the arrivals of two consecutive shocks which are too close to each other. That is, the system breaks down when the time between two successive shocks falls below a fixed threshold delta. In the literature, the delta-shock model has been mostly studied by assuming that the time between shocks have continuous distribution. In the present paper, the discrete time version of the model is considered. In particular, a proper waiting time random variable is defined based on a sequence of two-state Markov dependent binary trials and the problem of finding the distribution of the system's lifetime is linked with the distribution of the waiting time random variable, and we study the joint as well as the marginal distributions of the lifetime, the number of shocks and the number of failures associated with these binary trials.
Citation - WoS: 7
Citation - Scopus: 9
Reliability-Based Evaluation of Hybrid Wind-Solar Energy System
(Sage Publications Ltd, 2021) Devrim, Yilser; Eryilmaz, Serkan
In this article, a hybrid system that consists of a specified number of wind turbines and solar modules is considered. In particular, the system is modeled using weightedk-out-of-nsystem which is also known as a threshold system in reliability literature. The system under concern consists ofn1identical wind turbines andn2identical solar modules, and each turbine and module can be in one of two states as working or failed. The probability that the entire hybrid system withn=n1+n2components produces power at minimum levelkis computed and evaluated. The importance of single-wind turbine and solar module is also calculated to measure which renewable energy component is more critical and important. Extensive numerical results that are based on real data set are presented to illustrate the model.
Citation - WoS: 26
Citation - Scopus: 28
Reliability Assessment for Discrete Time Shock Models Via Phase-Type Distributions
(Wiley, 2021) Eryilmaz, Serkan; Kan, Cihangir
In this paper, particular shock models are studied for the case when the times between successive shocks and the magnitudes of shocks have discrete phase-type distributions. The well-known shock models such as delta shock model, extreme shock model, and the mixed shock model which is obtained by combining delta and extreme shock models are considered. The probability generating function and recursive equation for the distribution of the system's lifetime are obtained for the cases when the interarrival times between shocks and the magnitudes of shocks are independent and when they are dependent. System reliability is computed for particular interarrival distributions such as geometric, negative Binomial and generalized geometric distributions.

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