• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.229-235
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• 2021

The ability of entrepreneurs to arrange working capital is the key to maximizing the profitability of small- and medium-sized enterprises and the wealth of entrepreneurs. The study investigates the correlation between entrepreneurs' working capital management and the profitability of SMEs listed on six Gulf Cooperation Council (GCC) stock exchanges between 2019 and 2020. The secondary data is collected from the financial statements of SMEs listed on the six GCC stock exchanges. Actual sample for the research study was a total of 136 small- and medium-sized enterprises selected using purposive sampling methods. Four research models were considered in this analysis, all ending up affecting gross profits. The selected entrepreneurial SMEs were listed on six different Gulf Cooperation Council stock exchanges during 2019-2020. The fixed financial assets ratio, financial debt ratio, and company size are used as control variables and data were analyzed using multiple regression. The research results demonstrate that there is a statistically significant negative correlation between profitability measured by gross profit and cash cycle and the components of the cash cycle (including days of accounts receivable and days of inventory). The study further reveals that there is no significant correlation between gross profit and days of accounts payable.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.853-858
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• 2000

The working fluid from the combustor to the turbine stage of a gas turbine makes various boundary layer thickness. Since the inlet boundary layer thickness is one of the important factors that affect the turbine efficiency. It is necessary to investigate secondary flow and loss with various boundary layer thickness conditions. In the present study, the effect of various inlet boundary layer thickness on secondary flow and loss and the proper height of the boundary layer fences for various boundary layer thickness were investigated. Measurements of secondary flow velocity and total pressure loss within and downstream of the passage were taken under 5 boundary layer thickness conditions, 16, 36, 52, 69, 110mm. It was found that total pressure loss and secondary flow areas were increased with increase of thickness but they were maintained almost at the same position. At the fellowing research about the boundary layer fences, 1/6, 1/3, 1/2 of each inlet boundary layer thickness and 12mm were used as the fence heights. As a result, it was observed that the proper height of the fences was generally constant since the passage vortex remained almost at the same position. Therefore once the geometry of a cascade is decided, the location of the Passage vortex and the proper fence height are appeared to be determined at the same time. When the inlet boundary layer thickness is relatively small, the loss caused by the proper fence becomes bigger than endwall loss so that it dominates secondary loss. In these cases the proper fence hight is decided not by the cascade geometry but by the inlet boundary layer thickness as previous investigations.

• Communications of Mathematical Education
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• v.32 no.1
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• pp.59-77
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• 2018

This study aims to investigate reflections of secondary pre-service mathematics teachers and their changes through practicing as assistant teacher in mathematics classrooms. For the purpose of this study, research questions are addressed on the reflections and their changes. During the 2015 Spring semester, secondary pre-service mathematics teachers took a course related to working as assistant teachers in regular mathematics lessons in a middle school. This study selected cases of two pre-service teachers. The data such as reports on their practices and final meeting report with teachers were collected during the semester. The results showed that the secondary pre-service mathematics teachers reflected teachers, students, mathematics contents, and themselves in their reports. In addition, each participant showed different contents of reflections. This difference implied that secondary pre-service mathematics teachers could have different reflections according to the types of lessons that they participated in.

• Journal of Korean Clinical Nursing Research
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• v.26 no.3
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• pp.285-295
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• 2020

Purpose: The purpose of this study was to develop and validate a education nurse specialist-led educational satisfaction scale for nurses working at comprehensive nursing care service wards. Methods: A methodological study was conducted. A total of 237 nurses working at comprehensive nursing care service wards in a general hospital participated in this study. The scale was developed through literature reviews, in-depth interview, development of preliminary items, verification of content validity, development of secondary items, evaluation of construct validity, and extraction of final items. Analysis included exploratory factor analysis, pearson's analysis, and reliability analysis using cronbach's α. Results: The education nurse specialist-led educational satisfaction scale for nurses working at comprehensive nursing care service ward consisted of 21 items. Two factors (critical thinking disposition and clinical competency) were identified which explained 63.5% of the total variance. Cronbach's α of each factors were >.95. Conclusion: The results suggested that the education nurse specialist-led educational satisfaction scale for nurses working at comprehensive nursing care service wards demonstrated acceptable validity and reliability. Items of the instrument can assess the level of satisfaction with regards to education led by education nurse specialist among nurses working at comprehensive nursing care service wards.

• Journal of Power Electronics
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• v.18 no.4
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• pp.1190-1200
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• 2018

A current sourced bi-directional wireless power transfer (WPT) system is proposed to solve the problems that exist in the bi-directional WPT for vehicle-to-grid (V2G) systems. These problems include the fact that these systems are not safe enough, the output power is limited and the control methods are complicated. Firstly, the proposed system adopts two different compensation and control methods on both the primary and secondary sides. Secondly, based on an AC impedance analysis, the working principle is analyzed and the parameter configuration method with frequency stability is given. In order to output a constant voltage, a bi-directional DC/DC circuit and a controllable rectifier bridge are adopted, which are based on the "constant primary current, constant secondary voltage" control strategy. Finally, the effectiveness and feasibility of the proposed methods are verified by experimental results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.10
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• pp.993-1001
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• 2001

Experimental investigation on the performance of dual-evaporator refrigeration system with an ejector has been carried out. In this study, a hydrofluorocarbon (HFC) refrigerant R134a is chosen as a working fluid. The condenser and two-evaporators are made as concentric double pipes with counter-flow type heat exchangers. Experiments were performed by changing the inlet and outlet temperatures of secondary fluids entering condenser, high-pressure evaporator and low-pressure evaporator at test conditions keeping a constant compressor speed. When the external conditions (inlet temperatures of secondary fluid entering condenser and one evaporator) are fixed, results show that coefficient of performance (COP) increases as the inlet temperature of the other evaporator rises. It is also shown that the COP decreases as the mass flaw rate ratio of suction fluid to motive fluid increases. The COP of dual-evaporator refrigeration system with an ejector is superior to that of a single-evaporator vapor compression system by 3 to 6%.

• International Journal of Air-Conditioning and Refrigeration
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• v.10 no.4
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• pp.201-210
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• 2002

Experimental investigation on the performance of dual-evaporator refrigeration system with an ejector has been carried out. In this study, a hydrofluorocarbon (HFC) refrigerant R134a is chosen as a working fluid. The condenser and two-evaporators are made as concentric double pipes with counter-flow type heat exchangers. Experiments were peformed by changing the inlet and outlet temperatures of secondary fluids entering condenser, high-pressure evaporator and low-pressure evaporator at test conditions keeping a constant compressor speed. When the external conditions (inlet temperatures of secondary fluid entering condenser and one of the evaporators) are fixed, results show that coefficient of performance (COP) increases as the inlet temperature of the other evaporator rises. It is also shown that the COP decreases as the mass flow rate ratio of suction fluid to motive fluid increases. The COP of dual-evapo-rator refrigeration system with an ejector is superior to that of a single-evaporator vapor compression system by 3 to 6%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.571-574
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• 2000

In this study, Tin oxide thin film for secondary battery was deposited on Pt/Ti/Si(100). It was fabricated by r.f. reactive sputtering with Tin metal target. At constant power (130W), pressure (Base 5$\times$10$^{-6}$ Torr, working 5$\times$10$^{-3}$ Torr) and at room temperature, it was fabricated by Ar/O2 gas ratio. After deposition, we got AFM & SEM to investigated surface of thin films and had XRD to find crystalline of thin films. Charge/discharge characteristics were carried out in 1M LiPF$_{6}$ , EC:DMC = 1:1 liquid electrolyte using lithium metal at room temperature.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2366-2372
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• 2023

Are borate and silicate glasses suitable for working as shieling materials against fast neutrons? To correctly answer the above question, some silicate, and borate-based glasses were fabricated and irradiated with various doses of fast neutrons varied between 1.73 and 12.10 MGy. The color and hardness of the fabricated glasses were affected by the fast neutron fluence where the transparent glasses turned colored as well as the hardness of the fabricated glasses was decreased. The gamma-ray spectrometric analysis shows a high activity concentration produced in the barium borate glasses due to the formation of radioisotopes Ba-131 and Ba-133 reaches to 5.92E+05 Bq and 4.25E+03 Bq, respectively for sample Cd-5 Batch 3. Additionally, the gamma-ray spectrometric analysis for the sodium silicate glasses shows low activity concentrations emitted from isotopes formed due to the activation of Y₂O₃-associated impurities. These activities are low compared to that emitted by barium borate-based glasses.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.9
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• pp.1058-1065
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• 2004

In the present study, characteristics of steady state laminar flows of a straight duct connected to a 180$^{\circ}$ curved duct were examined in the entrance region through experimental and numerical analyses. For the analysis, the governing equations of laminar flows in the Cartesian coordinate system were applied. Flow characteristics such as velocity profiles, and secondary flows were investigated numerically and experimentally in a square cross-sectional straight duct by the PIV system and a CFD code(STAR CD). For the PIV measurement, working fluid produced from mosquito coils smoke. The experimental data were obtained at 9 points dividing the test sections by 400 mm. Experimental and numerical results can be summarized as follows. Critical Reynolds number, Recr which indicates transition from laminar steady flow to transition steady flow was 2,150. As Reynolds number, Re, was increased, dimensionless velocity profiles at the outer wall were increased due to the effect of the centrifugal force and the secondary flows. The intensity of a secondary flow became stronger at the inner wall rather than the outer wall regardless of Reynolds number.