Özbey, Mehmet Furkan
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M. F. Ozbey
Özbey, Mehmet Furkan
Ö.,Mehmet Furkan
Mehmet Furkan, Ozbey
O., Mehmet Furkan
Ö., Mehmet Furkan
O.,Mehmet Furkan
M.F.Özbey
M.,Özbey
M., Ozbey
Mehmet Furkan, Özbey
Mehmet Furkan Özbey
Özbey,M.F.
Ozbey, Mehmet Furkan
Ozbey,M.F.
M. F. Özbey
Ozbey,Mehmet Furkan
M.F.Ozbey
Özbey, Mehmet Furkan
Ö.,Mehmet Furkan
Mehmet Furkan, Ozbey
O., Mehmet Furkan
Ö., Mehmet Furkan
O.,Mehmet Furkan
M.F.Özbey
M.,Özbey
M., Ozbey
Mehmet Furkan, Özbey
Mehmet Furkan Özbey
Özbey,M.F.
Ozbey, Mehmet Furkan
Ozbey,M.F.
M. F. Özbey
Ozbey,Mehmet Furkan
M.F.Ozbey
Job Title
Araştırma Görevlisi
Email Address
furkan.ozbey@atilim.edu.tr
Main Affiliation
Mechanical Engineering
Status
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Scholarly Output
13
Articles
11
Citation Count
57
Supervised Theses
1
13 results
Scholarly Output Search Results
Now showing 1 - 10 of 13
Master Thesis İç Ortamda Ortalama Radyan Sıcaklığını Elde Etmek için Farklı Yöntemlerin Doğruluğunun Karşılaştırılması(2021) Özbey, Mehmet Furkan; Turhan, Cihan; Lotfısadıgh, Bahram; Energy Systems Engineering; Mechanical EngineeringAmerikan Isıtma Soğutma ve Klima Mühendisleri Birliği (ASHRAE), ısıl konforu bir kişinin bulunduğu ortamdaki memnuniyetini ifade eden öznel ve zihinsel değerlendirme ile elde edilen zihin koşulları olarak tanımlanmıştır. Isıl konfor, geleneksel olarak Fanger'in Ortalama Tahmini Oy (PMV) / Memnuniyetsizliklerin Tahmini Yüzdesi (PPD) metodu ve kişilerin davranışlarını da içeren adaptif ısıl konfor metotları ile elde edilmektedir. Isıl konfor parametreleri kişisel parametreler (giysi değeri ve metabolizma hızı) ve çevresel parametreler (hava sıcaklığı, bağıl nem, hava hızı ve ortalama radyan sıcaklığı) olarak üzere iki farklı kategoride ele almaktadır. Bu parametreler arasında, Ortalama Radyan Sıcaklık ölçülmesinin ve hesaplanmasının karmaşık olmasından dolayı elde edilmesi zor bir faktördür. İç ortamlarda ortalama radyan sıcaklığı elde etme yaklaşımları hesaplama yöntemleri, ölçüm yöntemleri ve varsayımlar gibi farklı yöntemlere dayanmaktadır. Ancak hesaplama yöntemlerinin karmaşık olması ve ölçüm yöntemleri için kullanılacak ölçüm aletlerinin pahalı ve elde edilmesi zor araçlar olması araştırmacıları doğruluğu kesin olmayan varsayımlara yönlendirmektedir. Bu nedenle, bu çalışmanın amacı ortalama radyan sıcaklığın elde edilme yöntemlerinin ölçüm yöntemlerinden birisi olan ve bu çalışma için üretilen küre termometresini referans alıp diğer metotlar ile karşılaştırılarak tüm yöntemlerin doğruluğunu bulmaktır. Bu çalışmada Köppen- Geiger sınıflandırmasına göre Csb tipi iklim bölgesinde bulunan bir test odası seçilmiştir ve ortalama radyatif sıcaklığı elde etmek için kullanılan 2 farklı hesaplama yöntemi ve 8 farklı varsayım yerinde ölçümle referans metodu ile karşılaştırılmıştır. Sonuçlar, ortalama radyan sıcaklığı elde etmek için varsayımların veya hesaplama yöntemlerinin kullanılmasının, referans yönteme kıyasla %9,1'e varan bir hataya neden olduğunu ortaya koydu.Article Citation - WoS: 15Citation - Scopus: 16Sensitivity Analysis of the Effect of Current Mood States on the Thermal Sensation in Educational Buildings(Wiley-hindawi, 2022) Ozbey, Mehmet Furkan; Ceter, Aydin Ege; Orfioglu, Sevval; Alkan, Nese; Turhan, Cihan; Energy Systems Engineering; Mechanical Engineering; Department of PsychologyAdaptive thermal comfort is a model which considers behavioral and psychological adjustments apart from Fanger's Predicted Mean Vote (PMV)/Percentage of Dissatisfied (PPD) method. In the literature, the differences between the PMV/PPD method and adaptive thermal comfort were mainly considered in aspects of behavioral adjustments in an environment. Conversely, limited studies related to psychological adjustments were considered in detail for thermal comfort. This study purposes to investigate the effects of current mood state subscales on thermal sensation of the occupants for the first time in the literature. To this aim, the Profile of Mood States (POMS) questionnaire is used to determine the mood state of the occupants with six different subscales: Anger, Confusion, Vigor, Tension, Depression, and Fatigue. The experiments were conducted in a university study hall in Ankara, Turkey, which is in warm-summer Mediterranean climate (Csb) according to Koppen-Geiger Climate Classification. The distributions of each subscale were examined via Anderson Darling and Shapiro-Wilk tests accordingly given responses from the occupants. The sensitivity analysis was applied to the six subscales of the POMS with Monte Carlo simulation method by considering the distributions of each subscale. The results revealed that the current mood state has a crucial effect on the thermal sensation of the occupants. The subscales of the Depression and Vigor were found as the most vital ones among the six subscales. Only the pure effects of the Vigor and Depression would change the thermal sensation of the occupants 0.31 and 0.30, respectively. The Confusion was determined as the least effective subscale to the thermal sensation of the occupants. Moreover, with the combination of all the six subscales, the thermal sensation might change up to 1.32. Findings in this study would help researchers to develop the personalized thermal comfort systems.Article Citation - WoS: 11Citation - Scopus: 12A Novel Comfort Temperature Determination Model Based on Psychology of the Participants for Educational Buildings in a Temperate Climate Zone(Elsevier, 2023) Ozbey, Mehmet Furkan; Turhan, Cihan; Energy Systems Engineering; Mechanical EngineeringMaintaining thermal comfort in the educational buildings is vital due to the impacts on learning effectiveness of students. Therefore, development of a proper comfort temperature in educational buildings is a must. In naturally ventilated and mixed-mode buildings, the adaptive thermal comfort model, which considers additively psychological, and behavioural factors to the Fanger's PMV/PPD model, is commonly applied based on regression analyses. However, the psychological adjustments based on current mood state are very limited in these adaptive thermal comfort models. Therefore, this study focuses on the psychological adjustments in terms of Profile of Mood States in order to predict comfort temperature of students in a case building. The experiments are conducted in a university on a temperate climate zone for a long period-data including both heating and cooling seasons. In this study, the comfort temperatures for each student are determined via Griffith method for the case building. Moreover, the current mood states of students are assessed utilizing the Profile of Mood States survey, which are collected via a developed mobile application. As a conclusion, the relation between the current mood state of the students and comfort temperature are statistically investigated. The results show that a Griffith constant are found as 0.332/K and mean annual comfort temperature is found as 21.32 degrees C in the case building. Additionally, a significant difference is found in the comfort temperatures among the students who have more, or fewer concerns than typically reported. The novelty of the study is to present a comfort temperature determination model which considers human psychology as a starter study in the literature.Article Citation - WoS: 6Citation - Scopus: 5The Importance of the Calculation of Angle Factors To Determine the Mean Radiant Temperature in Temperate Climate Zone: a University Office Building Case(Sage Publications Ltd, 2022) Ozbey, Mehmet Furkan; Turhan, Cihan; Energy Systems Engineering; Mechanical EngineeringThermal comfort depends on four environmental (air velocity, relative humidity, air temperature, mean radiant temperature) and two personal (clothing insulation and metabolic rate) parameters. Among all parameters, the mean radiant temperature (t(r)) is the most problematic variable in thermal comfort studies due to its complexity. Measurement methods, calculation methods and assumptions are mostly used to obtain the t(r). Researchers mainly prefer to obtain the t(r) via measurement methods or assumptions due to their easiness compared to the calculation methods. Besides, some researchers use constant values of angle factors in calculation methods. However, using constant values is not proper for every indoor environment, and it causes wrong estimations in the t(r) and thus the thermal comfort. This paper gives the importance of calculation of angle factors, with an example of a university office building in temperate climate zone, according to the ISO 7726. The angle factors of the room were calculated for a seated occupant from the centre of gravity in three different locations and compared with the constant angle factors. The results indicate that a significant difference (MAPE of 1.02) was found in the t(r) values, which were obtained by calculation of constant values of angle factors.Article A Case Study on the Assumption of Mean Radiant Temperature Equals To Indoor Air Temperature in a Free-Running Building(2021) Özbey, Mehmet Furkan; Turhan, Cihan; Energy Systems Engineering; Mechanical EngineeringThermal comfort is basically affected by environmental (mean radiant temperature, indoor air temperature and relative humidity and air velocity) and personal parameters (clothing value and activity level). Mean Radiant Temperature is the most complicated parameter among all thermal comfort parameters due to the difficulty of measurement and calculation processes. Calculation methods are not preferred by the researchers because of the complexity of obtaining angle factors while the measurement methods require very expensive devices such as globe thermometers and radiometers. On the other hand, assumptions are commonly used in thermal comfort studies because of their simplicities. One of the most frequently used assumptions expresses the equality of mean radiant temperature to indoor air temperature. However, the accuracy of this assumption needs further experimental research in order to evaluate thermal comfort, especially in free-running buildings. To this aim, this study proposes to determine the accuracy of the assumption of mean radiant temperature equals to indoor air temperature in a free-running building where Adaptive Thermal Comfort approach is applied in summer condition. Environmental parameters are measured via objective sensors, while adaptive thermal comfort is assessed by a software program. The statistical results show that there are significant deviations between two parameters in summer conditions for a free-running building.Article Citation - WoS: 14Citation - Scopus: 15Effect of Pre-And Post-Exam Stress Levels on Thermal Sensation of Students(Elsevier Science Sa, 2021) Turhan, Cihan; Ozbey, Mehmet Furkan; Energy Systems Engineering; Mechanical EngineeringThe Predicted Mean Vote and Predicted Percentage of Dissatisfied (PMV/PPD) method is used worldwide to assess thermal comfort. The PMV/PPD method traditionally depends on four environmental parameters; air temperature, relative humidity, mean radiant temperature and air velocity, and two personal parameters; metabolic rate and clothing insulation. However, accurate modelling of thermal comfort requires consideration of psychological impacts, as well as associated physical responses to the environment. This paper investigates the effect of one of the psychological parameters; stress level on the thermal sensation of students for male and female which can be a sufficient limitation of the accuracy of thermal comfort/sensation models. Actual Thermal Sensation (ATS) and Profile of Mood States (POMS) are used to examine the effect of stress level on the thermal sensation. Pre-test-Post-test Control (PPC) experimental design is conducted on the students in a university, Ankara, Turkey, which has a Csb type climate zone according to Koppen-Geiger climate classification. First, students are split into two random groups; control and experimental groups. The students in experimental group are requested to attend exam while the students in control group read their favourite books. Then, students are subjected to pre-and post-exam surveys in order to understand the relationship between stress level and ATS. As a supportive analysis, Heart Rate (HR) and Skin Temperature (ST) are also included in the study as sympathetic responses of occupants to the thermal discomfort due to stress. Smart wristbands and infrared thermometers are used to measure Heart Rate and Skin Temperature of the students. Results showed that there is a difference between control group and experimental group before the exam (pre-test) except the ST of females. After the exam (post-test), there are no significant differences between two groups. (C) 2020 Elsevier B.V. All rights reserved.Article Citation - WoS: 13Citation - Scopus: 14A Comprehensive Comparison and Accuracy of Different Methods To Obtain Mean Radiant Temperature in Indoor Environment(Elsevier, 2022) Ozbey, Mehmet Furkan; Turhan, Cihan; Energy Systems Engineering; Mechanical EngineeringThermal comfort is defined as "the state of mind which expresses satisfaction with the thermal environment" by the American Society of Heating, Refrigerating and Air Conditioning Engineers in the standard of the ASHRAE55. Thermal comfort is affected by six main parameters which are split into two categories; personal (basic clothing insulation value and metabolic rate) and environmental (air temperature, relative humidity, air velocity, and mean radiant temperature) parameters. The mean radiant temperature is a problematic parameter in thermal comfort studies due to its complexity. The mean radiant temperature approaches are based on different techniques such as calculation methods, measurement methods, and assumptions. Although the assumptions are utilized by researchers to abstain complexity, their accuracies are uncertain. To this aim, this study purposes to find the accuracies of calculation and assumption methods by comparing with reference measurement method. An office building in a temperate climate zone is selected as a case study. Two calculation methods and eight assumptions on obtaining mean radiant temperature are compared via in-situ measurements. The results revealed that using assumptions or calculation methods to obtain the mean radiant temperature caused a significant error compared to the reference method and researchers should consider accuracies of these methods before utilizing them in their applications.Article Determination of Metabolic Rate From Physical Measurements of Heart Rate, Mean Skin Temperature and Carbon Dioxide Variation(Sakarya University, 2022) Özbey, M.F.; Çeter, A.E.; Turhan, C.; Energy Systems Engineering; Mechanical EngineeringThermal comfort depends on four environmental parameters such as air temperature, mean radiant temperature, air velocity and relative humidity and two personal parameters, including clothing insulation and metabolic rate. Environmental parameters can be measured via objective sensors. However, personal parameters can be merely estimated in most of the studies. Metabolic rate is one of the problematic personal parameters that affect the accuracy of thermal comfort models. International thermal comfort standards still use a conventional metabolic rate table which is tabulated according to different activity tasks. On the other hand, ISO 8996 underestimates metabolic rates, especially when the time of activity level is short and rest time is long. To this aim, this paper aims to determine metabolic rates from physical measurements of heart rate, mean skin temperature and carbon dioxide variation by means of nineteen sample activities. 21 male and 17 female subjects with different body mass indices, sex and age are used in the study. The occupants are subjected to different activity tasks while heart rate, skin temperature and carbon dioxide variation are measured via objective sensors. The results show that the metabolic rate can be estimated with a multivariable non-linear regression equation with high accuracy of 0.97. © 2022, Sakarya University. All rights reserved.Article Citation - WoS: 10Citation - Scopus: 11Integration of Psychological Parameters Into a Thermal Sensation Prediction Model for Intelligent Control of the Hvac Systems(Elsevier Science Sa, 2023) Turhan, Cihan; Ozbey, Mehmet Furkan; Lotfi, Bahram; Akkurt, Gulden Gokcen; Energy Systems Engineering; Mechanical Engineering; Department of Mechanical EngineeringConventional thermal comfort models take physiological parameters into account on thermal comfort models. On the other hand, psychological behaviors are also proven as a vital parameter which affects the thermal sensation. In the literature, limited studies which combine both physiological and psychological parameters on the thermal sensation models are exist. To this aim, this study develops a novel Thermal Sensation Prediction Model (TSPM) in order to control the HVAC system by considering both parameters. A data-driven TSPM, which includes Fuzzy Logic (FL) model, is developed and coded using Phyton language by the authors. Two physiological parameters (Mean Radiant Temperature and External Temperature) and one psychological parameter (Emotional Intensity Score (EIS) including Vigour, Depression, Tension with total of 32 subscales) are selected as inputs of the model. Besides the physiological parameters which are decided intentionally considering a manual ventilated building property, the most influencing three sub- psychological parameters on thermal sensation are also selected in the study. While the physiological parameters are measured via environmental data loggers, the psychological parameters are collected simultaneously by the Profile of Mood States questionnaire. A total of 1159 students are participated to the questionnaire at a university study hall between 15th of August 2021 and 15th of September 2022. The results showed that the novel model predicted Thermal Sensation Vote (TSV) with an accuracy of 0.92 of R2. The output of this study may help to develop an integrated Heating Ventilating and Air Conditioning (HVAC) system with Artificial Intelligence - enabled Emulators that also includes psychological parameters.Article Citation - WoS: 20Citation - Scopus: 20A Novel Data-Driven Model for the Effect of Mood State on Thermal Sensation(Mdpi, 2023) Turhan, Cihan; Ozbey, Mehmet Furkan; Ceter, Aydin Ege; Akkurt, Gulden Gokcen; Energy Systems Engineering; Mechanical EngineeringThermal comfort has an important role in human life, considering that people spend most of their lives in indoor environments. However, the necessity of ensuring the thermal comfort of these people presents an important problem, calculating the thermal comfort accurately. The assessment of thermal comfort has always been problematic, from past to present, and the studies conducted in this field have indicated that there is a gap between thermal comfort and thermal sensation. Although recent studies have shown an effort to take human psychology into account more extensively, these studies just focused on the physiological responses of the human body under psychological disturbances. On the other hand, the mood state of people is one of the most significant parameters of human psychology. Thus, this paper investigated the effect of occupants' mood states on thermal sensation; furthermore, it introduced a novel "Mood State Correction Factor" (MSCF) to the existing thermal comfort model. To this aim, experiments were conducted at a mixed-mode building in a university between 15 August 2021 and 15 August 2022. Actual Mean Vote (AMV) and Profile of Mood States (POMS) were used to examine the effect of mood state on thermal sensation. The outcomes of this study showed that in the mood states of very pessimistic and very optimistic, the occupants felt warmer than the calculated one and the MSCFs are calculated as -0.125 and -0.114 for the very pessimistic and very optimistic mood states, respectively. It is worth our time to note that the experiments in this study were conducted during the COVID-19 Global Pandemic and the results of this study could differ in different cultural backgrounds.
