Extended Cubic B-Spline Solution of the Advection-Diffusion Equation

Dursun Irk,Idris Dag,Mustafa Tombul 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.4

The collocation method based on the extended B-spline functions as trial functions is set up to find numerical solutions of the advection-diffusion equation numerically. The transport of the pollution is simulated by way of using solutions of the advectiondiffusion equation. Comparative results of use of both B-spline and extended B-spline in the collocation method are illustrated. It is concluded that a suitable selection of the free parameter of extended B-spline is shown to provide less error for the numerical solutions of the advection-diffusion equation with some boundary and initial conditions.

Effect of stress-strain curve changing with equal channel angular pressing on ultimate strength of ship hull stiffened panels

Dursun Murat Sekban,Hasan Olmez 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.78 No.4

Similar to other structures, ultimate strength values showing the maximum load that the structure can resist without damaging has great importance on ships. Therefore, increasing the ultimate strength values will be an important benefit for the structure. Low carbon steels used in ships due to their low cost and good weldability. Improving the ultimate strength values without interfering with the chemical composition to prevent of the weldability properties of these steels would be very beneficial for ships. Grain refinement via severe plastic deformation (SPD) is an essential strengthening mechanism without changing the chemical composition of metallic materials. Among SPD methods, equal channel angular pressing (ECAP) is one of the most commonly used one due to its capacity for achieving bulk ultrafine-grained (UFG) materials. When the literature is examined, it is seen that there is no study about ultimate strength calculation in ships after ECAP. Therefore, the mean purpose of this study is to apply ECAP to a shipbuilding low carbon steel to be able to achieve mechanical properties and investigate the alteration of ship hull girder grillage system’s ultimate strength via finite element analysis approach. A fine-grained (FG) microstructure with a mean grain size of 6 μm (initial grain size was 25 μm) was after ECAP. This microstructural evolution brought about a considerable increase in strength values. Both yield and tensile strength values increased from 280 MPa and 425 MPa to about 420 MPa and 785 MPa, respectively. This improvement in the strength values reflected a finite element method to determine the ultimate strength of ship hull girder grillage system. As a result of calculations, it was reached significantly higher ultimate strength values (237,876 MPa) compared the non-processed situation (192,986 MPa) on ship hull girder grillage system.

ON SPACELIKE ROTATIONAL SURFACES WITH POINTWISE 1-TYPE GAUSS MAP

Dursun, Ugur Korean Mathematical Society 2015 대한수학회보 Vol.52 No.1

In this paper, we study a class of spacelike rotational surfaces in the Minkowski 4-space $\mathbb{E}^4_1$ with meridian curves lying in 2-dimensional spacelike planes and having pointwise 1-type Gauss map. We obtain all such surfaces with pointwise 1-type Gauss map of the first kind. Then we prove that the spacelike rotational surface with flat normal bundle and pointwise 1-type Gauss map of the second kind is an open part of a spacelike 2-plane in $\mathbb{E}^4_1$.

Rotordynamic Coefficients in Staggered Labyrinth Seals

Dursun Eser,Yilmaz Dereli 대한기계학회 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.5

In this paper, the flow properties of staggered labyrinth seals are investigated. Leakage flowrates and pressure distributions are calculated for this seal. Then the dynamic stiffness and damping coefficients are calculated. The results are compared to the results of the some other papers.<br/>

Maximal Hypersurfaces of (m + 2)-Dimensional Lorentzian Space Forms

Dursun, Ugur Department of Mathematics 2008 Kyungpook mathematical journal Vol.48 No.1

We determine maximal space-like hypersurfaces which are the images of subbundles of the normal bundle of m-dimensional totally geodesic space-like submanifolds of an (m + 2)-dimensional Lorentzian space form $\tilde{M}_1^{m+2}$(c) under the normal exponential map. Then we construct examples of maximal space-like hypersurfaces of $\tilde{M}_1^{m+2}$(c).

Responses of the phenolic compounds of Zea mays under heavy metal stress

Dursun Kisa,Mahfuz Elmastas,Lokman Öztürk,Ömer Kayır 한국응용생명화학회 2016 Applied Biological Chemistry (Appl Biol Chem) Vol.59 No.6

Heavy metal toxicity is one of the major abiotic stresses caused by physiological and biochemical changes. Plants have evolved various phytochemical defense mechanisms to cope with this abiotic stress conditions. Phenolic compounds are one of the stress responses and have multiple roles in respect to adaptation of plants to the environment. In the present study, we aimed to evaluate the differential accumulation of various phenolics with HPLC in the leaves of corn exposed to increasing heavy metal doses in the plant growth medium. The application of Cd, Cu, and Pb increased the total phenolics in all treatments compared to control groups. Chlorogenic acid and rutin were the main phenolic compounds in respect to quantifying. However, the contents of caffeic acid, ferulic acid, and vanillic acid were comparatively lower than chlorogenic acid and rutin in all samples. The content of chlorogenic acid significantly increased and rutin slightly increased in the treatment of the heavy metals. The levels of caffeic acid and ferulic acid significantly decreased in all exposures of heavy metals compared to control groups. The content of vanillic acid changed according to heavy metal types and doses in the leaves of corn, and the low doses of Pb and Cd increased the level of vanillic acid. We show that there is a positive correlation with the total phenolic content and chlorogenic acid when the corn is exposed to Pb. Moreover, there are negative correlations between total phenolic compound and caffeic acid, ferulic acid in the application of Cu and Cd.

Diversity pedagogical content knowledge: a new conceptual framework and assessment across different teacher education programmes

Dursun Hakan,Claes Ellen,Agirdag Orhan 한국다문화교육학회 2021 Multicultural Education Review Vol.13 No.4

Previous work on multicultural teaching competence has mainly focused on teachers’ beliefs and attitudes towards ethnocultural diversity. Little attention has been paid to examine the nature of teachers’ ethnocultural diversity knowledge. Drawing upon Shulman’s model of pedagogical content knowledge, this study presents a novel theoretical framework and a performance-based assessment for examining teachers’ ethnocultural diversity knowledge. We collected data from 819 preservice teachers across six teacher education programmes in Belgium, Flanders. Our findings indicate that student teachers in Flanders have limited and low levels of cultural diversity knowledge and there is a significant variation between the mean scores of teacher education programmes. We conclude by arguing that teacher education institutions should make meaningful reforms to develop student teachers’ knowledge base regarding ethnocultural diversity.

Arrhythmogenic Noncompaction Cardiomyopathy: Is There an Echocardiographic Phenotypic Overlap of Two Distinct Cardiomyopathies?

Dursun Aras,Ozcan Ozeke,Serkan Cay,Firat Ozcan,Kazım Baser,Umuttan Dogan,Murat Unlu,Burcu Demirkan,Omac Tufekcioglu,Serkan Topaloglu 한국심초음파학회 2015 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.23 No.3

The clinical diagnosis of right ventricular (RV) cardiomyopathies is often challenging. It is difficult to differentiate the isolatedleft ventricular (LV) noncompaction cardiomyopathy (NC) from biventricular NC or from coexisting arrhythmogenic ventricularcardiomyopathy (AC). There are currently few established morphologic criteria for the diagnosis other than RV dilation andpresence of excessive regional trabeculation. The gross and microscopic changes suggest pathological similarities between, orcoexistence of, RV-NC and AC. Therefore, the term arrhythmogenic right ventricular cardiomyopathy is somewhat misleading asisolated LV or biventricular involvement may be present and thus a broader term such as AC should be preferred. We describe anunusual case of AC associated with a NC in a 27-year-old man who had a history of permanent pacemaker 7 years ago due tosecond-degree atrioventricular block.

A Rosacea Case Involving One Side of the Face Accompanied by Demodex Infestation: Unilateral Rosacea Fulminans

( Dursun Turkmen ) 대한피부과학회 2019 Annals of Dermatology Vol.31 No.1

터키인 학습자를 위한 의미범주에 따른 한국어 감정표현 어휘 난이도 위계화

Essiz Dursun 이화어문학회 2019 이화어문논집 Vol.48 No.-

This study aims to determine the hierarchy of difficulty level of Korean emotion words in relation to its meaning for Turkish learners. The first step in this study was to select the right words for Turkish learners of Korean. Word selection methods were introduced, and an appropriate method was chosen for the study. After selecting the method, 59 Korean emotion words were chosen and compared with Turkish emotion words which can be minimal equivalents of the Korean emotion words. During the process of comparison, 40 to 50 sentences were used for each Korean emotion word. As a result of the comparison, Korean emotion words were classified into the three dimensions of Lado’s theory of difficulty levels: ‘correspondence’, ‘differentiation’, and ‘new category’; with each category referring to a level of difficulty. There were 37 words in ‘correspondence’ which are level one words that are easy to acquire, 13 words in ‘differentiation’ which are level two words and therefore more difficult to acquire than the words in level one, and 9 words in ‘new category’ which are level three words and considered the most difficult in this classification. In these three dimensions, emotion words equivalent for Korean emotion words were introduced by describing the similarities and differences between the two languages. Finally, some extra tasks were suggested for future studies. 본 연구는 터키인 한국어 학습자를 위하여 한국어 감정표현 어휘를 두 언어 간 의미관계에 의하여 난이도를 위계화하는 데 목적을 두고 있다. 이를 위하여 선행 연구에서 제시된 감정표현 어휘 목록을 통해 한국어교육에서 사용이 유용한 감정표현 어휘 58개를 선정하였다. 어휘 선정과정이 끝난 후 이들 어휘가 감정의 의미만으로 등장하는 맥락 40~50개를 선별하여 터키어에서 해당되는 단어와 의미를 대조분석하였다. 이어서 분석 결과를 바탕으로 각 한국어 감정표현 어휘에 해당하는 터키어 감정표현 어휘의 의미가 어느 정도 일치하는지 분석한 후 라도(Lado)의 어려움의 단계 중 적합한 단계로 분류하였다. 서로 의미가 비슷하고, 의미를 전달하는 데 문제를 발생시키지 않는 한국어 감정표현 어휘를 ‘대응 범주’에, 터키어에서 단어 하나로 표현이 가능한 반면 한국어에서 여러 단어로 표현이 가능한 어휘를 ‘차별화 범주’에, 터키어에서 대응이 없거나 의미전달이 맥락상 임의적으로 이루어지는 어휘들을 ‘새로운 범주’에 포함하였다. 따라서 ‘대응 범주’는 난이도가 낮고, ‘차별화 범주’는 난이도가 중간이며. ‘새로운 범주’는 난이도가 높은 어휘들로 결정하였다. 결론에서 본 연구의 후속 연구로서의 과제 두 가지를 소개하였다.