Browsing by Author "Sariyer, Görkem"
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Book Part Citation - Scopus: 2An (s S) inventory optimization problem: A case study for a hospital(IGI Global, 2019) Gizem Sağol; Gorkem Sariyer; Banu Yetkin Yetkin Ekren; Mustafa Gökalp Ataman; Ataman, Mustafa Gökalp; Sariyer, Görkem; Sağol, Gizem; Ekren, Banu YetkinInventory management is one essential lever to use the resources efficiently. However managing inventories in hospitals is a challenging task because of the several issues: a high service level of medical supplies is required under the unpredictable demand medical products constitute a significant portion of the overall costs and the management of these supplies requires considerable effort to check the levels to track usage and to distribute them. Therefore it is pertinence to apply operations research tools to cope with the managerial issues of the hospital inventory system. In this chapter the authors implement an (s S) inventory model by using simulation in a case study of a hospital in Izmir Turkey. They aim to analyze the unpredictable nature of demand of medical supplies in this hospital and its implications on the developed inventory policy. © 2022 Elsevier B.V. All rights reserved.Article Citation - WoS: 6Citation - Scopus: 6Child Abuse and Neglect Among Children Who Drop Out of School: A Study in Izmir- Turkey(ROUTLEDGE JOURNALS TAYLOR & FRANCIS LTD, 2016) Zeynep Sofuoglu; Gorkem Sariyer; Fulya Aydin; Sinem Cankardas; Birsu Kandemirci; Sariyer, Görkem; Aydin, Fulya; Cankardeş, Sinem; Cankardas, Sinem; Sofuoğlu, Zeynep; Kandemirci, BirsuChild abuse and neglect (CAN) and dropping out of school have long been recognized as pervasive social problems globally and Turkey is no exception. This study aims to explore the prevalence and incidence of CAN in children who drop out of school of Turkey using the ISPCAN Child abuse Screening Tool Children's Version which is an appropriate tool for multinational comparisons. Data from a convenience sample of children who drop out of school age 11 13 and 16 from Izmir were collected either by interviews or by self-completion. The results show that compared to children who do not drop out of school children who drop out of school have higher rates of psychological and physical abuse and neglect within the family. This study not only highlights the need for preventive laws for CAN and dropping out of school but also points to direction for future research.Article Çin Finansal Piyasalarında Covid-19 Ateşi: Döviz Piyasası ve Hisse Senedi Piyasası Arasındaki Etkileşim(2022) serpil kahraman; görkem sariyer; Kahraman, Serpil; Sariyer, GörkemCOVID-19 pandemisinin ekonomiler üzerindeki etkileri farklı olsa da finansal piyasalar benzer bir yol izlemiştir. Finansal ekonomi yaklaşımları eklenmeyen bir dış şok neticesinde ülkelerin öncelikle finans piyasalarının etkileneceğini ortaya koymaktadır. Bu doğrultuda dışsal bir etkide ilk aşamada gelişmekte olan ülkelerin borsaları veya döviz kuru piyasası etkilenmekte ikinci aşamada ise bu etki diğer piyasaya sıçramaktadır. Çalışma pandemi öncesi ve pandemi sonrası dönemleri karşılaştırarak pandeminin Çin borsası ve döviz piyasası üzerindeki ön etkisini COVID-19 verileri ve ilgili istatistikler (günlük yeni vaka sayısı yeni ölüm oranları) Pearson korelasyon testi uygulayarak araştırmaktadır. Ayrıca SSEC index ve CNY döviz kurlarının günlük dağılımları karşılaştırmaları olarak box plotlar ile gösterilmiştir. Zira ilk etkilenen piyasanın belirlenmesi piyasalardaki yüksek volatilitenin ve risk unsurunun giderilmesi anlamında politika yapıcılara yol gösterici olacaktır. Sonuçlar iki piyasa arasında önemli bir etkileşim olduğunu ve her iki piyasanın da rastgele davranmadığını göstermektedir. Bu bağlantı rastgele bir yürüyüşe (random walk) karşı makroekonomik politikaları belirlemek için oldukça önemlidir. Para politikası müdahalelerinin finansal piyasaların etkinliğini artırmada olumlu etkisinin olup olmadığı makalenin temel araştırma sorusudur. Araştırmaların bulgularına göre her ne kadar hisse senedi fiyatları rastgele yürüyüşe göre hareket etse de Etkin Piyasa Hipotezinin dayandığı gibi bilgiye dayalı bir fiyat hareketi olduğu görülmektedir. İzleyen süreçte belirsizliğin nispeten azalması ve kötümser beklentiler nedeniyle Çin para piyasasının artık yükseliş eğiliminde olduğu söylenebilir.Book Part Fighting Against COVID-19: The Role of Consolidated Fiscal Policies and Transparency in Data Sharing(Springer Nature, 2023) Gorkem Sariyer; Ece Acar; Sariyer, Görkem; Acar, EceWith COVID-19 the importance of integrity and transparency in health systems was once again highlighted all over the world. All countries took many fiscal and non-fiscal precautions to fight against this pandemic trying to protect the functionality of health systems and to minimize the damage to the public by keeping the spread of the pandemic under control. In addition to non-fiscal responses like curfews travel bans social distance closure of public areas isolation etc. countries also made fiscal responses by allocating budgets only to combat the pandemic. Fiscal responses were also split into two categories: the entire budget allocated for the fight against the pandemic and the budget allocated only to health issues. The budgets under both categories were announced by many counties at the beginning of each quarter starting from October 2020 January 2021 and April 2021. However from the global context it was observed that there were very serious differences between the fiscal responses namely financial support provided by the countries. Also while some countries did not share any data in this area it was also observed that some of the other countries did not take any fiscal responses. In this study which will be developed by examining the data of many countries in depth and comparatively we aim to analyze the success of countries that share their data in a transparent regular way in managing the COVID-19 pandemic. This study highlights not only the consolidated fiscal policies but also the integrity and transparency in data sharing policies of health systems to fight with this pandemic and to decrease the possible risk in economies arising from this pandemic in the long run. © 2024 Elsevier B.V. All rights reserved.Book Part Citation - Scopus: 2Modeling and Forecasting the Daily Number of Emergency Department Visits Using Hybrid Models(IGI Global, 2020) Gorkem Sariyer; Ceren Öcal; Öcal, Ceren; Sariyer, GörkemIn this study linear regression and neural network-based hybrid models are developed for modelling the daily ED visits. Month and week of the year day of the week and period of the day are used as input variables of the linear regression model. Generated forecasts and the residuals are further processed through a multilayer perceptron model to improve the performance of forecasting. To obtain forecasts for daily number of patient visits aggregation is used where the obtained periodical forecasts are summed up. By comparing the performances of models in generating periodical and dailyforecasts this chapter not only shows that hybrid model improves the forecasting performance significantly but also aggregation fits well in practice. © 2022 Elsevier B.V. All rights reserved.Article Pricing in M/M/1 queues when cost of waiting in queue differs from cost of waiting in service(2017) görkem sariyer; Sariyer, GörkemService providers can adjust the entrance price to the state of the demand in real life service systems where the customers' decision to receive the service is based on this price state of demand and other system parameters. We analyzed service provider's short and long term pricing problems in unobservable M/M/1queues having the rational customers where for customers the unit cost of waiting in the queue is higher than unit cost of waiting in the service. We showed that waiting in the queue has a clear negative effect on customers' utilities hence the service provider's price values. We also showed that in the short term monopolistic pricing is optimal for congested systems with high server utilization levels whereas in the long term market capturing pricing is more profitableArticle Throughput Analysis of Transfer Lines in Transient State: Using Exact Analytical Methods(2018) Mehmet Cemali DİNÇER; görkem sariyer; Sariyer, Görkem; Dinçer, Mehmet CemaliTransfer line is a serial arrangement of machines where buffers are used to separate two consecutive machines. This special type of production systems have high production volumes. In the design and operation of transfer lines throughput analysis is essential. Considering the transient state of the systems this paper presents theoretical analysis for throughput rate of transfer lines. For the short transfer lines having a unique machine and two machines we derive throughput rate expected value and variance functions. We use these functions in performance evaluation of production systems. Besides these formulations can be used while analyzing longer transfer lines which can easily be decomposed into smaller sub-systemsArticle TÜRK ANA METAL SANAYİ FİNANSAL PERFORMANS DEĞERLENDİRMESİ: AHP VE TOPSIS UYGULAMASI(2021) Ece Acar; görkem sariyer; Sariyer, Görkem; Acar, EceFinansal performans şirketlerin hem finansal hem de finansal olmayan politikalarının sonuçlarını yansıtarakkaynakların etkin kullanımını ve riskliliklerini değerlendirir. Bu nedenle rekabetçi iş dünyasında finansalperformans değerlendirmesi çok önemlidir. Çelik ve demir endüstrisi hem makine hem de emek yoğun birendüstridir ve buna bağlı olarak bu endüstri firmaları oldukça rekabetçi bir ortamda faaliyet göstermektedir.Dolayısıyla bu çalışmanın amacı Türk demir-çelik sektörünün finansal performansını değerlendirmektir. Buamaç doğrultusunda Borsa İstanbul'da 2017 yılı içinde işlem gören 17 ana metal sanayi firmasının finansaloranları hesaplanmaktadır. Çalışmada likidite verimlilik kârlılık ve sermaye yapısı oranları finansalperformansın ana ölçütü olarak kabul edilmiştir. Analitik Hiyerarşik Süreç (AHP) kullanılarak bu kriterler veher birinin ilgili alt kriterleri değerlendirmiş ve ağırlıklandırılmıştır. Ardından TOPSIS aracılığı ile bu ağırlıklar 17firmayı sıralamak için kullanılmıştır. Elde edilen sıralama 2017 yılında şirketlerin kapanış fiyatlarına göresıralama ile karşılaştırılmış ve 15 şirkette (%88.235) iki sıralamanın çok yakın sonuçlar verdiği görülmüştür. Bunedenle AHP ve TOPSIS'in birleştirilmesinin finansal performans değerlendirmesinde kullanılabileceğisonucuna varılmıştır.Article Citation - WoS: 12Citation - Scopus: 15Use of data mining techniques to classify length of stay of emergency department patients(INDEX COPERNICUS INT, 2019) Gorkem Sariyer; Ceren Ocal Tasar; Gizem Ersoy Cepe; Sariyer, Görkem; Tasar, Ceren Ocal; Cepe, Gizem Ersoy; Öcal Taşar, CerenEmergency departments (EDs) are the largest departments of hospitals which encounter high variety of cases as well as high level of patient volumes. Thus an efficient classification of those patients at the time of their registration is very important for the operations planning and management. Using secondary data from the ED of an urban hospital we examine the significance of factors while classifying patients according to their length of stay. Random Forest Classification and Regression Tree Logistic Regression (LR) and Multilayer Perceptron (MLP) were adopted in the data set of July 2016 and these algorithms were tested in data set of August 2016. Besides adopting and testing the algorithms on the whole data set patients in these sets were grouped into 21 based on the similarities in their diagnoses and the algorithms were also performed in these subgroups. Performances of the classifiers were evaluated based on the sensitivity specificity and accuracy. It was observed that sensitivity specificity and accuracy values of the classifiers were similar where LR and MLP had somehow higher values. In addition the average performance of the classifying patients within the subgroups outperformed the classifying based on the whole data set for each of the classifiers.Book Part Citation - Scopus: 1Utilizing mHealth applications in emergency medical services of Turkey(Springer International Publishing, 2018) Gorkem Sariyer; Mustafa Gökalp Ataman; Ataman, Mustafa Gokalp; Sariyer, Görkem[No abstract available]
