Ex) Article Title, Author, Keywords
Ex) Article Title, Author, Keywords
Abstract : In this study, we used a 3D printer, vacuum forming, and soft molding methods to fabricate a lens array. We printed the first prototype of the lens array using a 3D printer. Then, we used vacuum forming to smooth the surface of the prototype with a melted plastic sheet. Subsequently, the smoothed prototype was used to create a soft mold using polydimethylsiloxane. We poured thermal epoxy into a soft mold and allowed it to harden, forming transparent epoxy lens arrays. The fabricated lens array produced good images of objects and exhibited excellent lens performance. Furthermore, the focal length of the lens arrays was varied by adjusting the radius of curvature of the prototype. The proposed fabrication approach offers the potential for students to create their lenses and practice optical theory.
Abstract : A service provider must understand the unique characteristics of the users to recommend appropriate products. Factors such as personality, social class, and hobbies can be used to identify the user and improve recommendations. This information can be obtained through direct questioning or analyzing user-generated content such as blog posts. This study uses a large language model and transfer learning to extract specific information, such as taste and knowledge, from text. The author’s characteristics are then embedded using a recurrent neural network and a triplet loss metric learning methodology to distinguish between users. Qualitative insights into their similarities were then obtained from analyzing the label distribution in the embedding space.
Abstract : Potassium silicate solution (PSS) added with Y3Al5O12:Ce3+(YAG:Ce3+) phosphors was synthesized by using a solid-state reaction method. The crystal structure, morphology, and luminescence properties of the phosphors were measured for various PSS concentrations. The X-ray diffraction pattern of the phosphors shows that the addition of PSS promotes the formation of a garnet structure at lower temperature than commercial YAG phosphors. FE-SEM images show that the addition of PSS promotes the growth of particle size and aggregation. With the addition of 10 wt.% of PSS, the PL spectra show that the emission intensity at 533 nm is 20% higher than the normal phosphor. In determining the performance of PSS-added YAG:Ce3+ phosphors, white LEDs were fabricated by combining blue LEDs and phosphors. The phosphor exhibited lower color temperature because of the enhancement of yellow emission. Result shows that PSS can be applied as a flux, which decreases the synthesis temperature of YAG phosphors.
Abstract : For this qualitative study, we conducted an in-depth analysis of unexpected situations that occur in sixth-grade electric circuit lessons in a South Korean elementary school, the causes of these situations, and factors affecting the teacher’s responses. We performed a detailed observation of electric circuit lessons taught by an experienced teacher and carried out pre-lesson and post-lesson interviews. The causes of unexpected situations were found to be students’ neglect of electrical components, poor quality electrical components, images in the textbook, and real-life examples and analogies used by the teacher. The situations considered unexpected by the teacher included an electric circuit that did not light up, incorrect experimental results, and student questions regarding the teacher’s real-life examples. The teacher handled these unexpected situations by explaining that electrical components are consumables, giving real-life examples, providing opportunities for inquiry, and limiting textbook use. These responses originated from the teacher’s belief that science teaching should be student-centered and inquiry-based, and needs to emphasize the relationship between science and real-life experience. The study offers implications for science education in general and the teaching of electric circuits, which presents significant difficulties for elementary school teachers.
Abstract : This paper proposes two methods for calculating current ﬂow through an electric bulb, which is a nonlinear electric device: the graphical method and the optimal auxiliary function method. The currents ﬂowing through an electric bulb of 2.5 V − 0.3 A with room temperature resistance R0 = 1.3 Ω according to the terminal voltages of it are calculated via the methods and are compared with the measured currents. Compared with the measured currents, the currents calculated via the graphical method have error rates below 5.95%, and the currents calculated via the optimal auxiliary function method have error rates below 2.44% in the operating region of the electric bulb. These low error rates demonstrate the validity and practicality of the two methods.
YeonJung PARK, Joonghoe DHO*
New Phys.: Sae Mulli 2021; 71(5): 450-456
Jongwon PARK, Insun LEE*
New Phys.: Sae Mulli 2021; 71(5): 476-489
Chang-Duk KIM*, Younjung JO, Nguyen Tam Nguyen TRUONG
New Phys.: Sae Mulli 2021; 71(5): 422-426