This study examines the impact of students’ anxiety, due to online learning, in different learning environments: a synchronous (Zoom) and asynchronous learning environment (YouTube) to compare students’ conceptual understanding of electric circuits. Multiple linear regression and factor analyses were conducted to examine the factor of students’ anxiety and conceptual understanding. A sample of 99 vocational students participated in the study, including YouTube (n = 49) and Zoom (n = 50) groups. The DIRECT was used to diagnose test for conceptual understanding in the electric circuits, and OTAI was used to assess anxiety in online learning test. The OTAI consists of three factors: psychological, physiological, and online. The results showed that students’ anxiety, in some factors, affected their conceptual understanding of the electric circuits in both groups. However, there was a significant increase in conceptual understanding in both treatment groups. Although the students’ conceptual understanding had a slight increase, online learning has to improve to reduce the anxiety of learners.

This study used the Area Elimination Method (AEM) of transformer design with transformer characteristic simulation. The multidimensional variable of physical parameters such as magnetic density, current density, voltage and coil turn was performed. This method was used in designing the 8000 kVA 22,000–3300/1905 V oil-type large distribution transformer. The result from a design found that the objective function tries to reduce the material to be used, and less core steel, less conductors, less transformer oil or less transformer tanks may cause an increasing load loss or increasing temperature rise, but we have calculated the temperature in the winding and design the radiator fins at the same time. After designing the transformer with AEM and it being manufactured in the production process, the transformer was tested according to IEC standards. It was confirmed that the power loss tests with no load yielded lower power loss than the standard value. In addition, the transformer passed the satisfaction test and the results of this design were built and tested with IEC 60076 standards. The information from the design using the Area Elimination Method could be a guarantee of standardized accuracy for oil distribution transformers. This also saves time and increases design efficiency for transformer designers.

This research has developed a process for producing ZnO thin film from DEZn deposited onto a PET substrate with low-pressure, high-frequency Ar + O₂ plasma using a chemical vapor deposition technique. The aim is to study the film production conditions that affect electrical properties, optical properties, and thin film surfaces. This work highlights the use of plasma energy produced from a mixture of gases between Ar + O₂. Plasma production is stimulated by an RF power supply to deliver high chemical energy and push ZnO atoms from the cathode inside the reactor onto the substrate through surface chemical reactions. The results showed that increasing the RF power in plasma production affected the chemical reactions on the substrate surface of film formations. Film preparation at an RF power of 300 W will result in the thickest films. The film has a continuous columnar formation, and the surface has a granular structure. This results in the lowest electrical resistivity of 1.8 × 10⁻⁴ Ω. In addition, when fabricated into a DSSC device, the device tested the PCE value and showed the highest value at 5.68%. The reason is due to the very rough surface nature of the ZnO film, which increases the scattering and storage of sunlight, making cells more efficient. Therefore, the benefit of this research is that it will be a highly efficient prototype of thin film production technology using a chemical process that reduces production costs and can be used in the industrial development of solar cells.

This research has developed a process for producing ZnO thin film from DEZn deposited onto a PET substrate with low-pressure, high-frequency Ar + O2 plasma using a chemical vapor deposition technique. The aim is to study the film production conditions that affect electrical properties, optical properties, and thin film surfaces. This work highlights the use of plasma energy produced from a mixture of gases between Ar + O2. Plasma production is stimulated with an RF power supply to deliver high chemical energy and push ZnO atoms from the cathode inside the reactor onto the substrate through surface chemical reactions. The results showed that increasing the RF power in plasma production affected the chemical reactions on the substrate surface of film formation. The film preparation at RF power 300 W will give the thickest films. The film has a continuous columnar formation, and the surface has a granular structure. This results in the lowest electrical resistivity of 1.8 x 10-4 Ω-cm. In addition, when fabricated into a DSSC device, the device tested the PCE value and showed the highest value at 5.68%. This is due to the very rough surface nature of the ZnO film, which increases the scattering and storage of sunlight, making cells more efficient. Therefore, the benefit of this research is that it will be a highly efficient prototype of thin film production technology using a chemical process that reduces production costs and can be used in the industrial development of solar cells.

Dye-sensitized solar cells (DSSCs) are among the most widely studied thin-film solar cells because of their cost-effectiveness, low toxicity, and simple fabrication method. However, there is still much scope for replacing current DSSC materials due to their high cost, low volume, and lack of long-term stability. Accordingly, indium tin oxide (ITO)-nanorod films were fabricated by electron (E)-beam evaporation using the glancing angle deposition method in this study. Then, the ITO-nanorod was treated with oxygen plasma via a bias-magnetron radio-frequency (RF) sputtering process to improve the efficiency of DSSCs under a varying gas flow rate of 20, 40, 60, 80, and 100 sccm. The field emission scanning electron microscopy (FE-SEM) investigation of the ITO film structure revealed that the obtained nanorod structures have slightly different diameters. At the same time, an increase in the oxygen flow rate resulted in a rougher film surface structure. In this, the lower sheet resistance was received because of rougher morphology. When comparing the DSSCs efficiency (η) test results, we found that at a gas flow rate of 100 sccm, the highest efficiency value showed 9.5%. On the other hand, the ITO-nanorod without plasma treatment exhibited the lowest η. Hence, plasma technology can be practically applied to improve the η of DSSC devices. This study will be a prototype of a highly advanced solar cell manufacturing method for the solar cell industry.