E-ISSN: 2148-9386
Journal of ETA Maritime Science - JEMS Maritime Sci: 9 (4)
Volume: 9  Issue: 4 - 2021
1.Full Issue

Pages I - II

2.Research Environment After COVID-19
Selçuk Nas
doi: 10.4274/jems.2021.60783  Page 221
Abstract |Full Text PDF

3.Effect of Business Operation Period on the Relationship Between Knowledge Management Applications and Ship Performance
Murat Yorulmaz, Ahmet Karabacak
doi: 10.4274/jems.2021.66049  Pages 222 - 232
This study aims to examine the effect of knowledge management (KM) on the cargo performance (CP) and navigational performance (NP) of ships and to determine whether the business operation period of the firm has a moderating effect in this relationship by means of KM applications used in businesses operating in international markets. This work also investigates the impact of the business operation period on the ship’s CP and NP. Data were obtained by administering a questionnaire to 451 employees who work in a total of 67 ship businesses operating in Turkey and analyzed using SPSS 22 Hayes (2019) Process macro (v3.4) and AMOS 22 programs. Findings indicated that the KM applied in ship businesses has a positive effect on both performances of ships, explaining about 17% and 13% of the change in their navigation performance and CP, respectively. This study concluded with suggestions to the managers of ship businesses on how to render their KM applications more efficiently and effectively.

4.Container Ship Investment Analysis Using Picture Fuzzy Present Worth Analysis
Eda Boltürk
doi: 10.4274/jems.2021.89156  Pages 233 - 242
Investment analysis plays an important role in today’s global engineering projects. The present worth analysis is an important investment analysis tool and method in engineering economics. These analyses are performed by humans, and human thoughts are hesitant. Fuzzy sets are frequently used in the literature to eliminate ambiguities in human thoughts. In 1965, Zadeh proposed fuzzy logic as a method of obtaining improved solutions to problems. Since then, fuzzy logic has extended to include hesitant fuzzy sets, q-rung fuzzy sets, Pythagorean fuzzy sets, picture fuzzy sets, type-2 fuzzy sets, Fermatean fuzzy sets, and Spherical fuzzy sets. As can be seen in the literature, present worth analysis has also been extended to its fuzzy versions, such as hesitant present worth analysis and spherical fuzzy present worth analysis. In this study, picture fuzzy present worth analysis is proposed as a new extension of present worth analysis that uses picture fuzzy sets in to create an alternative usage in investment analysis. The introduced method is presented step by step, and a sensitivity analysis is presented with risky parameters in the present worth analysis. Furthermore, the proposed method is compared with spherical fuzzy and classic crisp present worth analysis. The proposed method is used in container ship investment analysis, and future suggestions are provided in the conclusion section.

5.Developing a Scale to Measure the Institutionalization Level of Maritime Family Businesses
Barış Demir, Leyla Tavacıoğlu
doi: 10.4274/jems.2021.16680  Pages 243 - 255
Institutionalization is an important strategy that can help family businesses survive in developing market conditions. Measuring the institutionalization level of companies can improve the understanding of current corporate governance statuses and reveal institutionalization problems. Here, we developed a scale to measure the institutionalization level of maritime family businesses. Data obtained by questionnaires from 193 office employees in 177 Turkish family-owned ship management companies were analyzed by exploratory factor analysis and confirmatory factor analysis via structural equation modeling in the SPSS 23.0 and AMOS 23.0 statistical programs as quantitative methods. Following rigorous scale development procedures, a scale was developed consisting of 14 items and three dimensions. The three dimensions are effective organizational structure, internal audit, and transfer of authority. Based on the results, the scale was determined to be reliable and valid. Finally, the implications of the study were discussed and suggestions were given for additional studies.

6.Effects of Power Distance on Organizational Commitment: A Study on Maritime Faculty Students
Umut Yıldırım, Arda Toygar, Ahmet Lutfi Tunçel
doi: 10.4274/jems.2021.24650  Pages 256 - 265
This study investigates the effect of power distance on the organizational commitment of maritime faculty students. The hypotheses developed in this context were analyzed using the structural equation modeling method based on data collected from 406 participants. The results from one-dimensional (1D) evaluation indicated that organizational power distance had a positive impact on the organizational commitment levels of maritime faculty students. However, there are several studies in the literature that show that this effect may lead to inconsistent results in 1D examination. These conflicting results necessitate a multidimensional analysis of the research. Evaluation of the sub-dimensions included in the study revealed that: (1) acceptance of power had positive effects on calculative and moral commitment, (2) justification of power on moral commitment, and (3) acquiescence of power on calculative, alienative, and moral commitment.

7.Experimental and Numerical Investigation of the Effects of Different Draft and Wave Frequency Combinations on the Performance of a Fixed OWC Wave Energy Converter
Deniz Öztürk, Mehmet Ozan Şerifoğlu
doi: 10.4274/jems.2021.82712  Pages 266 - 273
The oscillating water column (OWC) device is a versatile type of wave energy converter, which is one of the promising and popular systems in the use of sustainable supplies of energy. The present research aims to investigate the hydrodynamic performance of a cylindrical OWC device within several approaches, thereby observing the effects of varying wave heights and vertical positions on the flow inside the device. A series of experiments and numerical analyses were performed on a fixed OWC device with an open orifice for three different drafts (0.25, 0.40, and 0.55 m) and regular waves with frequencies ranging between 0.4 Hz and 1.2 Hz. Present results were compared with the results derived from the analytical calculations. The trends observed in the analytical solutions in a response amplitude operator for the heave motion of the internal water free surface with the wave frequency variation for all drafts were consistent with the numerical and experimental results. The findings reveal that the maximum water displacement inside the OWC increases as the draft increases, and the optimal frequency at which this value appears decreases.

8.The Coupling Effect on Torsional and Longitudinal Vibrations of Marine Propulsion Shaft System
Akile Neşe Halilbeşe, Osman Azmi Özsoysal
doi: 10.4274/jems.2021.68094  Pages 274 - 282
The propulsion shaft system is one of the essential parts of the ships due to its reliability and stabilization directly affecting the safety in operation. The propulsion system transmits the torque generated by the engine to the propeller via the main shaft. During its navigation, torsional, longitudinal, and transversal vibrations inevitably occur, and precautions must be taken during the design stage to prevent system damage and reduce power transmission efficiency. In this article, three dissimilar models numerically generated by the lumpedmass method are used to investigate the harmonic conclusions of forced coupled torsional and longitudinal vibrations of the system. Numerical results correlated with the experimental results at rotational speed and load acting onto the propulsion shaft system. A further finding is to create a third method upon discussing the facts revealed by analyzing the advantages and disadvantages of the models, especially considering differences between the first two models.

9.Frequency-Domain Ship Motion Code with Python Programming Language
Seyyit Nafiz Arslan, Atakan Yavuz, Ferdi Çakıcı
doi: 10.4274/jems.2021.48303  Pages 283 - 291
In this study, a frequency-domain seakeeping code is established. A container ship was selected as an example to demonstrate the outputs of the code in different headings, ranging from the beam to head waves. Tasai’s method is used to obtain two-dimensional hydrodynamic added mass and damping coefficients. For different loading conditions, the damping values for the roll motion can be obtained using Ikeda’s method. Froude Krylov and Diffraction terms for pitch and heave motions are computed using the head seas approximation. A user-friendly interface is designed for presenting frequency-domain analyses. Vertical motions, vertical accelerations, and some derived motion characteristics, such as deck wetness, slamming, and absolute vertical accelerations are plotted as transfer functions. The entire procedure is implemented using Python code.

10.Post GMC’21 Conference
Osman Turan
doi: 10.4274/jems.2021.51423  Pages 292 - 293
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11.Reviewer Index

Page E1
Abstract |Full Text PDF

12.Author Index

Page E2
Abstract |Full Text PDF

13.Subject Index

Pages E3 - E4
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