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      • KCI등재SCIESCOPUS

        Prediction of concrete compressive strength using non-destructive test results

        Hamit,Erdal,Mürsel,Erdal,Osman,Şimşek,Halil,İbrahim,Erdal 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.4

        Concrete which is a composite material is one of the most important construction materials. Compressive strength is a commonly used parameter for the assessment of concrete quality. Accurate prediction of concrete compressive strength is an important issue. In this study, we utilized an experimental procedure for the assessment of concrete quality. Firstly, the concrete mix was prepared according to C 20 type concrete, and slump of fresh concrete was about 20 cm. After the placement of fresh concrete to formworks, compaction was achieved using a vibrating screed. After 28 day period, a total of 100 core samples having 75 mm diameter were extracted. On the core samples pulse velocity determination tests and compressive strength tests were performed. Besides, Windsor probe penetration tests and Schmidt hammer tests were also performed. After setting up the data set, twelve artificial intelligence (AI) models compared for predicting the concrete compressive strength. These models can be divided into three categories (i) Functions (i.e., Linear Regression, Simple Linear Regression, Multilayer Perceptron, Support Vector Regression), (ii) Lazy-Learning Algorithms (i.e., IBk Linear NN Search, KStar, Locally Weighted Learning) (iii) Tree- Based Learning Algorithms (i.e., Decision Stump, Model Trees Regression, Random Forest, Random Tree, Reduced Error Pruning Tree). Four evaluation processes, four validation implements (i.e., 10-fold cross validation, 5-fold cross validation, 10% split sample validation & 20% split sample validation) are used to examine the performance of predictive models. This study shows that machine learning regression techniques are promising tools for predicting compressive strength of concrete.

      • KCI등재SCOPUS

        Challenges and Some New Directions in Channel Coding

        Erdal,Arıkan,Najeeb,ul,Hassan,Michael,Lentmaier,Guido,Montorsi,Jossy,Sayir 한국통신학회 2015 Journal of communications and networks Vol.17 No.4

        Three areas of ongoing research in channel coding are surveyed, and recent developments are presented in each area: Spatially coupled low-density parity-check (LDPC) codes, nonbinary LDPC codes, and polar coding.

      • KCI등재

        On PC⋆-closed sets

        Erdal,Ekici,A.,Nur,Tunc 충청수학회 2016 충청수학회지 Vol.29 No.4

        '스콜라' 이용 시 소속기관이 구독 중이 아닌 경우, 오후 4시부터 익일 오전 7시까지 원문보기가 가능합니다.

        In this paper, the concept of PC⋆-closed sets is introduced. PC⋆-closed sets contain pre∗ I-open and pre∗ I-closed sets, RPCI and pre∗ I-closed sets, RPCI and weakly Irg-closed sets.

      • KCI등재

        Properties of Regular Set-connected Functions

        Erdal,Ekici 경북대학교 자연과학대학 수학과 2004 Kyungpook mathematical journal Vol.44 No.3

        In 1999, Dontchev, Ganster and Reilly introduced the notion of regular set-connected functions. In this paper, properties of regular set-connected functions are investigated and obtained.

      • KCI등재SCOPUS

        The Association between Subclinical Hypothyroidism and Epicardial Adipose Tissue Thickness

        Erdal,Belen,Aleks,Degirmencioglu,Ertugrul,Zencirci,Fatih,Fahri,Tipi,Özgür,Altun,Gültekin,Karakus,Ays¸en,Helvacı,Aycan,Esen,Zencirci,Ezgi,Kalaycıoglu 대한심장학회 2015 Korean Circulation Journal Vol.45 No.3

        Background and Objectives: Subclinical hypothyroidism (SH) is considered to be a potential risk factor for cardiovascular disease. Epicardial adipose tissue (EAT) thickness is also closely related to cardiovascular disorders. The aim of this study was to evaluate whether SH is associated with higher EAT thickness. Subjects and Methods: Fifty-one consecutive patients with SH and 51 healthy control subjects were prospectively enrolled into this trial. Thyroid hormone levels, lipid parameters, body mass index, waist and neck circumference, and EAT thickness measured by echocardiography were recorded in all subjects. Results: Mean EAT thickness was increased in the SH group compared to the control group (6.7±1.4 mm vs. 4.7±1.2 mm, p<0.001). EAT thickness was shown to be correlated with thyroid stimulating hormone level (r=0.303, p=0.002). Multivariate logistic regression analysis revealed that EAT thickness was independently associated with SH {odds ratio (OR): 3.87, 95% confidence interval (CI): 1.92–7.78, p< 0.001; OR: 3.80, 95% CI: 2.18–6.62, p<0.001}. Conclusion: Epicardial adipose tissue thickness is increased in patients with SH compared to control subjects, and this increase in EAT thickness may be associated with the potential cardiovascular adverse effects of SH.

      • KCI등재SCOPUS

        The comparative analysis of optimal designed web expanded beams via improved harmony search method

        Erdal,,Ferhat 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.4

        This study aims at comparing the optimum design of two common types open web expanded beams: with hexagonal openings, also called castellated beams and beams with circular openings referred to as cellular beams. The minimum weights of both beams are taken as the objective functions while the design constraints are respectively implemented from The Steel Construction Institute Publication Numbers 5 and 100. The design methods adopted in these publications are consistent with BS5950 parts. The formulation of the design problem considering the limitations of the above mentioned turns out to be a discrete programming problem. Improved harmony search algorithm is suggested to compare the optimum design of mentioned web-expanded beams to analysis the performance of both beams. The design algorithms based on the technique select the optimum Universal Beam sections, dimensional properties of hexagonal and circular holes and total number of openings along the beam as design variables.

      • KCI등재SCOPUS

        Effects of coloring procedures on zirconia/veneer ceramics bond strength

        Erdal,Eroglu,Pelin,Ozat,İlkin,Tuncel 대한치과보철학회 2014 The Journal of Advanced Prosthodontics Vol.6 No.6

        PURPOSE The most common failure seen in restorations with a zirconia core is total or layered delamination of the ceramic veneer. In the present study, the shear bond strengths between veneering ceramics and colored zirconia oxide core materials were evaluated. MATERIALS AND METHODS Zirconia discs (15 × 12 × 1.6 mm) were divided into 11 groups of 12 discs each. Groups were colored according to the Vita Classic scale: A3, B1, C4, D2, and D4. Each group was treated with the recommended shading time for 3 s, or with prolonged shading for 60 s, except for the control group. Samples were veneered with 3 mm thick and 3.5 mm in diameter translucent ceramic and subjected to shear test in a universal testing machine with a crosshead speed of 1 mm/min. One-way analysis of variance (ANOVA) and Tukey's HSD tests were used for comparisons of the groups having the same shading times. A paired t-test was used for groups of the same color (3 s/60 s). RESULTS Among the 11 groups investigated C4 (3 s) had the highest bond strength with a value of 36.40 MPa, while A3 (3 s) showed the lowest bond strength with a value of 29.47 MPa. CONCLUSION Coloring procedures can affect zirconia/ceramic bond strength. However, the results also showed that bond strengths of all the investigated groups were clinically acceptable.

      • KCI등재SCOPUS

        Effect of biofilm formation, and biocorrosion on denture base fractures

        Erdal,Cosgun,Simel,Ayyildiz,Gulay,Uzun,Alper,Ergin,Cem,Sahin 대한치과보철학회 2013 The Journal of Advanced Prosthodontics Vol.5 No.2

        PURPOSE The aim of this study was to investigate the destructive effects of biofilm formation and/or biocorrosive activity of 6 different oral microorganisms. MATERIALS AND METHODS Three different heat polymerized acrylic resins (Ivocap Plus, Lucitone 550, QC 20) were used to prepare three different types of samples. Type "A" samples with "V" type notch was used to measure the fracture strength, "B" type to evaluate the surfaces with scanning electron microscopy and "C" type for quantitative biofilm assay. Development and calculation of biofilm covered surfaces on denture base materials were accomplished by SEM and quantitative biofilm assay. According to normality assumptions ANOVA or Kruskal-Wallis was selected for statistical analysis (α=0.05). RESULTS Significant differences were obtained among the adhesion potential of 6 different microorganisms and there were significant differences among their adhesion onto 3 different denture base materials. Compared to the control groups after contamination with the microorganisms, the three point bending test values of denture base materials decreased significantly (P<.05); microorganisms diffused at least 52% of the denture base surface. The highest median quantitative biofilm value within all the denture base materials was obtained with P. aeruginosa on Lucitone 550. The type of denture base material did not alter the diffusion potential of the microorganisms significantly (P>.05). CONCLUSION All the tested microorganisms had destructive effect over the structure and composition of the denture base materials.

      • KCI등재

        Comparison of effects of the tacrolimus and cyclosporine A on the colon anastomosis recovery of rats

        Erdal,Uysal,Mehmet,Dokur 대한외과학회 2017 Annals of Surgical Treatment and Research Vol.92 No.6

        Purpose: This study aims to examine and compare the effects of immunosuppressant cyclosporine A (CsA) and tacrolimus (TAC) on colon anastomosis recovery. Methods: Forty rats were randomly divided into 4 groups. The 4 groups were determined as follows: control group; sham group, given %0.09 NaCl; TAC group, given 0.5 mg/kg/day tacrolimus; and CsA group, given 5 mg/kg/day CsA. A 6-cm midabdomen incision was performed on the rats. An incision of all layers on the right colon was performed. Then anastomosis was undertaken. Laparotomy was performed on the seventh day postoperation. The colon bursting pressures were evaluated, histopathological examinations were undertaken, and E-cadherin expression and tissue hydroxyproline levels were evaluated. Results: Statistically significant differences were observed among bursting pressures of the groups (P < 0.001). The value was significantly low in TAC and CsA groups when compared to control and sham groups (P < 0.05). The tissue hydroxyproline levels were significantly low in TAC group compared to control group (P = 0.03). Fibroblast density and neovascularization were significantly greater in the control group compared to the TAC group (P < 0.05). Levels of collagen had decreased significantly in TAC group compared to other groups (P < 0.05). Conclusion: Our study showed that TAC may have a negative effect of colon anastomosis recovery. The lowest anastomosis bursting pressure was detected in TAC group. Also, collagen, hydroxyproline, fibroblast, neovascularization and E-Cadherin levels were comparatively lower in TAC group. CsA did not cause any significant changes to tissue hydroxyproline, collagen, fibroblast, and E-Cadherin levels.

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