Researcher:
Balım, Haldun

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Master Student

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Haldun

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Balım

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Balım, Haldun

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2018 - 201912020 - 20211

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    Automated diagnosis of keratoconus from corneal topography
    (Assoc Research Vision Ophthalmology Inc, 2021) N/A; N/A; N/A; Department of Industrial Engineering; N/A; Taş, Ayşe Yıldız; Hasanreisoğlu, Murat; Balım, Haldun; Gönen, Mehmet; Şahin, Afsun; Faculty Member; Faculty Member; Master Student; Faculty Member; Faculty Member; Department of Industrial Engineering; School of Medicine; School of Medicine; Graduate School of Sciences and Engineering; College of Engineering; School of Medicine; 200905; 182001; N/A; 237468; 171267
    Purpose: Although visual inspection of corneal topography maps by trained experts can be powerful, this method is inherently subjective. Quantitative classification methods that can detect and classify abnormal topographic patterns would be useful. An automated system was developed to differentiate keratoconus patterns from other conditions using computer-assisted videokeratoscopy. Methods: This system combined a classification tree with a linear discriminant function derived from discriminant analysis of eight indices obtained from TMS-1 videokeratoscope data. One hundred corneas with a variety of diagnoses (keratoconus, normal, keratoplasty, epikeratophakia, excimer laser photorefractive keratectomy, radial keratotomy, contact lens-induced warpage, and others) were used for training, and a validation set of 100 additional corneas was used to evaluate the results. Results: In the training set, all 22 cases of clinically diagnosed keratoconus were detected with three false-positive cases (sensitivity 100%, specificity 96%, and accuracy 97%). With the validation set, 25 out of 28 keratoconus cases were detected with one false-positive case, which was a transplanted cornea (sensitivity 89%, specificity 99%, and accuracy 96%). Conclusions: This system can be used as a screening procedure to distinguish clinical keratoconus from other corneal topographies. This quantitative classification method may also aid in refining the clinical interpretation of topographic maps.
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    In vitro validation of a self-driving aortic-turbine venous-assist device for fontan patients
    (Elsevier, 2018) Türköz, Rıza; Department of Mechanical Engineering; N/A; N/A; N/A; N/A; Department of Mechanical Engineering; Pekkan, Kerem; Aka, İbrahim Başar; Tutsak, Ece; Ermek, Erhan; Balım, Haldun; Lazoğlu, İsmail; Faculty Member; PhD Student; Master Student; Other; Master Student; Faculty Member; Department of Mechanical Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; Graduate School of Sciences and Engineering; College of Engineering; 161845; N/A; N/A; N/A; N/A; 179391
    Background: Palliative repair of single ventricle defects involve a series of open-heart surgeries where a single-ventricle (Fontan) circulation is established. As the patient ages, this paradoxical circulation gradually fails, because of its high venous pressure levels. Reversal of the Fontan paradox requires an extra subpulmonic energy that can be provided through mechanical assist devices. The objective of this study was to evaluate the hemodynamic performance of a totally implantable integrated aortic-turbine venous-assist (iATVA) system, which does not need an external drive power and maintains low venous pressure chronically, for the Fontan circulation. Methods: Blade designs of the co-rotating turbine and pump impellers were developed and 3 prototypes were manufactured. After verifying the single-ventricle physiology at a pulsatile in vitro circuit, the hemodynamic performance of the iATVA system was measured for pediatric and adult physiology, varying the aortic steal percentage and circuit configurations. The iATVA system was also tested at clinical off-design scenarios. Results: The prototype iATVA devices operate at approximately 800 revolutions per minute and extract up to 10% systemic blood from the aorta to use this hydrodynamic energy to drive a blood turbine, which in turn drives a mixed-flow venous pump passively. By transferring part of the available energy from the single-ventricle outlet to the venous side, the iATVA system is able to generate up to approximately 5 mm Hg venous recovery while supplying the entire caval flow. Conclusions: Our experiments show that a totally implantable iATVA system is feasible, which will eliminate the need for external power for Fontan mechanical venous assist and combat gradual postoperative venous remodeling and Fontan failure.