Hasan Dağ

Dağ, Hasan

Name Variants

D., Hasan
Dağ, HASAN
DAĞ, HASAN
Hasan, Dag
HASAN DAĞ
Hasan DAĞ
DAĞ, Hasan
Daǧ H.
Hasan Dağ
Dağ, H.
Dağ,H.
D.,Hasan
Dağ, Hasan
Dag H.
Dag,H.
Dağ H.
Dag,Hasan
Dag, Hasan
H. Dağ
Da?, Hasan

Job Title

Prof. Dr.

Email Address

hasan.dag@khas.edu.tr

Main Affiliation

Management Information Systems

Scholarly Output

83

Articles

17

Citation Count

238

Supervised Theses

24 Scholarly Output Search Results

Now showing 1 - 10 of 38

Citation - Scopus: 0
Power consumption estimation using in-memory database computation
(Institute of Electrical and Electronics Engineers Inc., 2016) Dag,H.; Dağ, Hasan; Alamin,M.
In order to efficiently predict electricity consumption, we need to improve both the speed and the reliability of computational environment. Concerning the speed, we use in-memory database, which is taught to be the best solution that allows manipulating data many times faster than the hard disk. © 2016 IEEE.
Citation - WoS: 0
Parallel Implementation Of Iterative Rational Krylov Methods For Model Order Reduction
(IEEE, 2010) Yetkin, E. Fatih; Dağ, Hasan; Dağ, Hasan; Yetkin, Emrullah Fatih
Model order reduction (MOR) techniques are getting more important in large scale computational tasks like large scale electronic circuit simulations. In this paper we present some experimental work on multiprocessor systems for rational Krylov methods. These methods require huge memory and computational power especially in large scale simulations. Therefore these methods are fairly suitable for parallel computing.
Citation - Scopus: 5
Double Branch Outage Modeling and Its Solution Using Differential Evolution Method
(2011) Ceylan, Oğuzhan; Dağ, Hasan; Ozdemir, Aydogan; Ceylan, Oğuzhan; Dağ, Hasan
Power system operators need to check the system security by contingency analysis which requires power flow solutions repeatedly. AC power flow is computationally slow even for a moderately sized system. Thus fast and accurate outage models and approximated solutions have been developed. This paper adopts a single branch outage model to a double branch outage one. The final constrained optimization problem resulted from modeling is then solved by using differential evolution method. Simulation results for IEEE 30 and 118 bus test systems are presented and compared to those of full AC load flow in terms of solution accuracy. © 2011 IEEE.
Citation - WoS: 0
Power Consumption Estimation using In-Memory Database Computation
(Ieee, 2016) Dag, Hasan; Dağ, Hasan; Alamin, Mohamed
In order to efficiently predict electricity consumption, we need to improve both the speed and the reliability of computational environment. Concerning the speed, we use inmemory database, which is taught to be the best solution that allows manipulating data many times faster than the hard disk. For reliability, we use machine learning algorithms. Since the model performance and accuracy may vary depending on data each time, we test many algorithms and select the best one. In this study, we use SmartMeter Energy Consumption Data in London Households to predict electricity consumption using machine learning algorithms written in Python programming language and in-memory database computation package, Aerospike. The test results show that the best algorithm for our data set is Bagging algorithm. We also emphatically prove that R-squared may not always be a good test to choose the best algorithm.
Citation - WoS: 0
On the Selection of Interpolation Points for Rational Krylov Methods
(Springer-Verlag Berlin, 2012) Yetkin, E. Fatih; Dağ, Hasan; Dağ, Hasan; Yetkin, Emrullah Fatih
We suggest a simple and an efficient way of selecting a suitable set of interpolation points for the well-known rational Krylov based model order reduction techniques. To do this some sampling points from the frequency response of the transfer function are taken. These points correspond to the places where the sign of the numerical derivation of transfer function changes. The suggested method requires a set of linear system's solutions several times. But they can be computed concurrently by different processors in a parallel computing environment. Serial performance of the method is compared to the well-known H-2 optimal method for several benchmark examples. The method achieves acceptable accuracies (the same order of magnitude) compared to that of H-2 optimal methods and has a better performance than the common selection procedures such as linearly distributed points.
Citation - Scopus: 1
Heterosim: Heterogeneous Simulation Framework
(Association for Computing Machinery, 2009) Dursun, Taner; Dağ, Hasan; Dağ, Hasan
In order to arrange heterogeneous simulation executions it would be useful to have simulation tools that enable easy and fast creation of simulation sessions employing real-time software components beside simulation codes. Although there have been considerable amount of research activities in simulation community the current simulation tools are not sufficiently capable to support such a cooperation between components working in real-time and simulation-time. In this paper we propose a new approach for constructing hybrid simulations that leverages usage of simulation systems. We introduce HeteroSim a Java-based simulation system that can execute discrete event simulations by employing both simulation and real world software entities. This model is applicable to many software related areas such as scenario-based software testing and development of simulators. As a case study we are able to rely on this model in order to build simulations combining both the simulated elements of a High Performance Computing (HPC) system and already implemented elements of our Policy Based Management (PBM) framework so-called POLICE [1][2]. In this manner it may be possible to study the efficiency of POLICE on management of HPC systems.
Citation - Scopus: 6
Investigation of Cyber Situation Awareness Via Siem Tools: a Constructive Review
(Institute of Electrical and Electronics Engineers Inc., 2021) Ünal, U.; Dağ, Hasan; Kahya, C.N.; Kurtlutepe, Y.; Dağ, H.
Awareness, in the sense of security, builds the backbone of operations understanding the current and future cyber activities. Situation awareness has become the focal point of securing systems due to dynamic nature of cyber domain. Technological advancements cause the volatility to transform into upcoming challenges. Understanding those is the key to keep cyber Situation Awareness (SA) progression. Earlier studies define required steps to administer cyber SA. These steps (perceive, comprehend, project, and resolve) are also adapted to cyber domain. Rapid technological changes redefine the content of those and thus, it creates demands improving automated tools, which play as systematic factor in nurturing SA. As a system factor, SIEM tools can be basis for comprehending cyber domain. In this work, we investigate recent studies contributed mainly to SIEM (Security Information and Event Management) tool’s enhancement to evaluate current state and help predict upcoming challenges for maintaining awareness. We use various criteria in our investigation such as; architecture improvement, affected SIEM process, utilized CTI (Cyber Threat Intelligence) artefact, implementation area, and type of produced result. In doing so, we aim to impart upward trends on CSA (Cyber Situation Awareness) to academia and industry professionals. © 2021 IEEE
Citation - Scopus: 5
Power Flow Using Thread Programming
(2011) Dağ, Hasan; Dağ, Hasan; Soykan, Gürkan
Power flow problem which is one of the most important applications in power system is solved using OpenMP Application Program Interface (API) a thread based programming technique for the shared memory programming environments. The parallel implementation of power flow is tested on a shared memory machine with cache-coherent non-uniform memory access (ccNUMA) architecture. Results are presented for various power test systems. The thread programming based power flow program decreases the runtime substantially. OpenMP lets a user concentrate on his/her own work rather than the parallel programming details. OpenMP is a set of compiler directives and requires minimal knowledge regarding parallel programming. It can easily be used not only on the shared memory systems but also on the systems with hyper threading and multi-core technologies as well. Thus speeding up any kind of power system related study is now viable without having to have expensive parallel computers and extensive experience on theirs programming. Since todays' and future personal computers and servers will mostly be based on the multi-core technologies the proposed method is an alternative to hard-coded parallel programming. © 2011 IEEE.
Citation - WoS: 0
Citation - Scopus: 0
Comparison of Cost-Free Computational Tools for Teaching Physics
(IEEE, 2010) Er, Neslihan Fatma; Dağ, Hasan; Dağ, Hasan
It is widely accepted that it is quite difficult to engage today's students, from high schools to university, both in educational activities in class and "teaching" them physics due to their prejudices about the complexity of physics. The difficulty in capturing students' attention in class for a long time also plays a role in less effective teaching during learning activities. Research shows that students learn little from traditional lectures. According to constructivist learning theories, visual aids and hands-on activities play a major role in learning physics. In addition to laboratory work there are many computational tools for teaching physics, which help teachers and students in constructing a conceptual framework. With this in mind, this paper compares freeware and open source computational tools for teaching physics.
Citation - Scopus: 0
Post-outage state estimations for outage management
(IFAC Secretariat, 2011) Ceylan, Oğuzhan; Dağ, Hasan; Ozdemir, Aydogan; Ceylan, Oğuzhan; Dağ, Hasan
Real time outage information is required to the utility operators for outage management process. In addition to some basic information regarding the outage post-outage system status will help to improve the response to outages and management of system reliability. This paper presents particle swarm optimization based reactive power estimations for branch outages. Post outage voltage magnitudes and reactive power flows results for IEEE 14 and IEEE 30 bus systems are given. Simulation results show that post outage voltage magnitudes and reactive power flows can be computed with a reasonable accuracy. © 2011 IFAC.