Motivation to Lead and Shared Leadership in Teams

Zeynep Giraylar(Zeynep Giraylar ),Kyoosang Choi(Kyoosang Choi) 한국자료분석학회 2023 Journal of the Korean Data Analysis Society Vol.25 No.1

More companies have started to adopt a model of self-managed team as their primary work design. As work environments get more complex, an appointed leader alone cannot fulfill all the necessary leadership responsibilities of a team. In this manner, the shared leadership within a team is of great importance for today's work environments. The primary purpose of the present study was to examine an antecedent of shared leadership. Focusing on leadership motivation, this study investigated how team members’ motivation to lead affects shared leadership of the team. This study also examined the effects of shared leadership on team performance using an objective team performance measure, which little previous studies have investigated. Data were obtained from 57 teams consisting of 3 to 5 members. They performed a computer-based business strategy game. Findings showed that the teams consisting of members with a high level of motivation to lead scores were positively related to shared leadership and shared leadership significantly predicted team performance. Theoretical and practical implications of this study are also discussed.

Influence of modeling agents on the surface properties of an esthetic nano-hybrid composite

Kutuk, Zeynep Bilge,Erden, Ecem,Aksahin, Damla Lara,Durak, Zeynep Elif,Dulda, Alp Can The Korean Academy of Conservative Dentistry 2020 Restorative Dentistry & Endodontics Vol.45 No.1

Objective: The aim of this study was to evaluate the influence of different modeling agents on the surface microhardness (Vickers hardness number; VHN), roughness (Ra), and color change (ΔE) of a nano-hybrid composite with or without exposure to discoloration by coffee. Materials and Methods: Sixty-four cylinder-shaped nano-hybrid composite specimens were prepared using a Teflon mold. The specimens' surfaces were prepared according to the following groups: group 1, no modeling agent; group 2, Modeling Liquid; group 3, a universal adhesive (G-Premio Bond); and group 4, the first step of a 2-step self-adhesive system (OptiBond XTR). Specimens were randomly allocated into 2 groups (n = 8) according to the storage medium (distilled water or coffee). VHN, Ra, and ΔE were measured at 24 hours, 1 week, and 6 weeks. The Kruskal-Wallis test followed by the Bonferroni correction for pairwise comparisons was used for statistical analysis (α = 0.05). Results: Storage time did not influence the VHN of the nano-hybrid composite in any group (p > 0.05). OptiBond XTR Primer application affected the VHN negatively in all investigated storage medium and time conditions (p < 0.05). Modeling Liquid application yielded improved Ra values for the specimens stored in coffee at each time point (p < 0.05). Modeling Liquid application was associated with the lowest ΔE values in all investigated storage medium and time conditions (p < 0.05). Conclusion: Different types of modeling agents could affect the surface properties and discoloration of nano-hybrid composites.

Influence of modeling agents on the surface properties of an esthetic nano-hybrid composite

Kutuk Zeynep Bilge,Erden Ecem,Aksahin Damla Lara,Durak Zeynep Elif,Dulda Alp Can 대한치과보존학회 2020 Restorative Dentistry & Endodontics Vol.45 No.2

Objective: The aim of this study was to evaluate the influence of different modeling agents on the surface microhardness (Vickers hardness number; VHN), roughness (Ra), and color change (ΔE) of a nano-hybrid composite with or without exposure to discoloration by coffee. Materials and Methods: Sixty-four cylinder-shaped nano-hybrid composite specimens were prepared using a Teflon mold. The specimens' surfaces were prepared according to the following groups: group 1, no modeling agent; group 2, Modeling Liquid; group 3, a universal adhesive (G-Premio Bond); and group 4, the first step of a 2-step self-adhesive system (OptiBond XTR). Specimens were randomly allocated into 2 groups (n = 8) according to the storage medium (distilled water or coffee). VHN, Ra, and ΔE were measured at 24 hours, 1 week, and 6 weeks. The Kruskal-Wallis test followed by the Bonferroni correction for pairwise comparisons was used for statistical analysis (α = 0.05). Results: Storage time did not influence the VHN of the nano-hybrid composite in any group (p > 0.05). OptiBond XTR Primer application affected the VHN negatively in all investigated storage medium and time conditions (p < 0.05). Modeling Liquid application yielded improved Ra values for the specimens stored in coffee at each time point (p < 0.05). Modeling Liquid application was associated with the lowest ΔE values in all investigated storage medium and time conditions (p < 0.05). Conclusion: Different types of modeling agents could affect the surface properties and discoloration of nano-hybrid composites.

Design, Synthesis and Characterization of a pH-Sensitive DS/GM Hydrogel

Zeynep Özenir,Celile Demirbilek,Cemile Özdemir Dinç 한국고분자학회 2015 Macromolecular Research Vol.23 No.11

Dextran sulfate/glycidyl methacrylate (DS/GM) hydrogels were synthesized by intermolecular side-chain reaction of DS hydroxyl groups with monomeric crosslinking agent, GM in aqueous solutions at 75 oC in the basic medium in this study. The optimum conditions of effective crosslinking for DS/GM system were determined with changing amounts of crosslinker and initiator (benzoyl peroxide, BPO). The swelling abilities of the hydrogels were explained with determining of certain structural parameters for the hydrogel such as equilibrium water content, percentages of gellation, and swelling ratio. pH dependent swelling behaviors of hydrogels were investigated and swelling ability at basic medium was higher than that at acidic medium. Surface morphologies of DS and its hydrogels were examined by scanning electron microscope (SEM) and they compared. Structures and thermal stabilities of DS/ GM hydrogels were characterized by infrared (FTIR), thermal gravimetric analysis (TGA), differential thermal analysis (DTA), and Differential Scanning Calorimeter (DSC); effect of GM on crosslinking was investigated. The viscosities of DS/GM reaction products were recorded continuously as a function of time with rotary viscometer and gellation points of binary system reaction between DS and GM were determined via observed viscosity numbers, changes during reaction.

Medical and Dietary Therapy for Kidney Stone Prevention

Zeynep Gul,Manoj Monga 대한비뇨의학회 2014 Investigative and Clinical Urology Vol.55 No.12

The prevalence of kidney stone disease is increasing, and newer research is finding thatstones are associated with several serious morbidities. These facts suggest that emphasisneeds to be placed not only on stone treatment but also stone prevention. However, there is a relative dearth of information on dietary and medical therapiesto treat and avoid nephrolithiasis. In addition, studies have shown that there are manymisconceptions among both the general community and physicians about how stonesshould be managed. This article is meant to serve as a review of the current literatureon dietary and drug therapies for stone prevention.

A novel approach for olive leaf extraction through ultrasound technology : Response surface methodology versus artificial neural networks

Zeynep Ilbay,Selin Sahin,Kemal Büyükkabasakal 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.9

Response surface methodology (RSM) and artificial neural network (ANN) were used to evaluate the ultra-sound-assisted extraction (UAE) of polyphenols from olive leaves. To investigate the effects of independent parameterson total phenolic content (TPC) in olive leaves, pH (3-11), extraction time (20-60 min), temperature (30-60 oC) andsolid/solvent ratio (500 mg/10-20 mL) were selected. RSM and ANN approaches were applied to determine the bestpossible combinations of these parameters. Box-Behnken design model was chosen for designing the experimentalconditions through RSM. The second-order polynomial models gave a satisfactory description of the experimental data. Experimental parameters and responses were used to train the multilayer feed-forward networks with MATLAB. ANNproved to have higher prediction accuracy than that of RSM.

Analyses of the Structural and the Temperature-Dependent Magnetic Properties of Pine Resin and Pine Bark from the Oltu/Erzurum Region in Turkey

Zeynep Aygun,Necmi Yarbasi 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.7

In the present paper, our aim is to investigate the structural, compositional and temperaturedependent magnetic properties of pine resin and pine bark obtained from a yellow pine forest situated in Oltu/Erzurum, a tertiary depositional area, located on the central area of the Northeast Anatolian Fault Zone. With the purpose of understand the regional effects on pine resin and pine bark obtained from a yellow pine forest, electron paramagnetic resonance spectroscopy is used to determine paramagnetic features at different temperatures (room temperature, 65 ℃, 75 ℃ and 85℃). An X-ray diffraction experiment is performed to obtain the crystalline nature of the resin and the bark. Also, scanning electron microscopy and energy dispersive spectroscopy methods are preferred for analyzing the surface morphology and the elemental composition of the samples, respectively.

Mathematics teacher quality: its distribution and relationship with student achievement in Turkey

Zeynep Ebrar Yetkiner Özel 서울대학교 교육연구소 2013 Asia Pacific Education Review Vol.14 No.2

A main purpose of the present study was to investigate the distribution of qualified mathematics teachers in relation to students’ socioeconomic status (SES), as measured by parental education, among Turkish middle schools. Further, relationships between mathematics teacher quality indicators and students’ mathematics achievement were explored. Data from the 2007 Trends in International Mathematics and Science Study were used. Relationships between mathematics teacher quality and students’ mathematics achievement were investigated using hierarchical linear modeling. The current study identified SES-related inequities in access to qualified mathematics teachers in Turkey. Low-SES students were more likely to be taught by mathematics teachers who had less than 3 years of experience or who did not hold a degree in mathematics or mathematics education. On the other hand, years of experience and a degree in mathematics or mathematics education were found to be substantially related to Turkish eighth-grade students’ mathematics achievement. Low-SES students’ mathematics teachers were also more likely to report a lack of confidence in their preparation to teach various mathematics contents.

The effect of fiber reinforcement on behavior of Concrete-Filled Steel Tube Section (CFST) under transverse impact: Experimentally and numerically

Zeynep Yaman 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.82 No.2

This study presents an experimental and numerically study about the effects of fiber reinforcement ratio on the behavior of concrete-filled steel tubes (CFST) under dynamic impact loading. In literature have examined the behavior of GFRP and FRP wrapped strengthened CFST elements impact loads. However, since the direction of potential impact force isn't too exact, there is always the probability of not being matched the impact force of the area where the reinforced. Therefore, instead of the fiber textile wrapping method which strengthens only a particular area of CFST element, we used fiber-added concrete-filled elements which allow strengthening the whole element. Thus, the effect of fiber-addition in concrete on the behavior of CFST elements under impact loads was examined. To do so, six simply supported CFST beams were constructed with none fiber, 2% fiber and 10% fiber reinforcement ratio on the concrete part of the CFST beam. CFST beams were examined under two different impact loads (75 kg and 225 kg). The impactors hit the beam from a 2000 mm free fall during the experimental study. Numerical models of the specimens were created using ABAQUS finite element software and validated with experimental data. The obtained results such as; mid-span displacement, acceleration, failure modes and energies from experimental and numerical studies were compared and discussed. Furthermore, the Von Misses stress distribution of the CFST beams with different ratio of fiber reinforcements were investigated numerically. To sum up, there is an optimum amount limit of the fiber reinforcement on CFST beams. Up to this limit, the fiber reinforcement increases the structural performances of the beam, beyond that limit the fiber reinforcement decreases the performances of the CFST beam under transverse impact loadings.

Comparative Spectroscopic Characterization of Cultivated Agricultural Soils Situated in Volcanic Centers in the Eastern Part of Turkey

Zeynep Aygun 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.2

In this study, we aimed to investigate the characteristics of the cultivated agricultural lands located in volcanic regions in the Eastern part of Turkey. East Anatolian Volcanic Province has two well-known volcanic centers: S\"uphan and Nemrut. Samples used in this research were collected from the fields in Bitlis, G\"uroymak, Tatvan, Ahlat and Adilcevaz, which are situated in the foothills of the Nemrut and the S\"uphan volcanic mountains. In order to analyze and compare the structural and magnetic properties of these soil samples, which can show regional features, we used several spectroscopic techniques (electron paramagnetic resonance, X-ray diffraction, Fourier-transform infrared spectrophotometer, scanning electron microscopy, and energy dispersive spectroscopy). The obtained magnetic, structural and elemental results are discussed in detail in terms of whether the samples of these volcanic agricultural areas have different or similar characteristics.