• Korean Journal of Optics and Photonics
• /
• v.13 no.5
• /
• pp.449-454
• /
• 2002

We have studied the effects of incoherent pumping on EIA at the transition between the $F_g=2$ ground state and the $F_e=3$ excited state in $^{85}Rb\;D_1$-line. Generally, the studies about EIA have been done in the cycling transition, where the population has no loss to other states. In the case of EIA by using the $^{85}Rb\;D_1$ transition line, the population is transferred to the other hyperfine state due to optical pumping. We incoherently pumped the atoms from $F_g=3\;to\;F_g=2$ with the pumping beam, which is resonant at the transition from $F_g=3\;to\;F_g=2$. We were able to observe the effects of incoherent pumping depending on the power and the polarization of the pumping beam.

• Journal of Astronomy and Space Sciences
• /
• v.7 no.1
• /
• pp.1-10
• /
• 1990

The thermodynamic distribution of the vibrational states of ozone coupled with anharmonic predissociation produces an unusual isotopomeric pattern of oxygen molecules. The model presented here explains the experimental data obtained from the electric discharge of oxygen gas to produce ozone condensed on a quartz at 77K.

• Journal of Science Education
• /
• v.37 no.2
• /
• pp.374-388
• /
• 2013

The purpose of this study was to investigate pre-service physics teachers' perceptions on the physics education major curriculum. We surveyed 15 junior, and 13 senior college students of physics education major in an university in southern part of Korea. Among them, 24 participants(86 %) took the physics 1 course in high school and 22 participants(79 %) chose the physics 1 in their Korea Scholastic Aptitude Test. The responses showed that the most necessary part in pre-service students' learning was the understanding of high school level physics(36 %), and the understanding of introductory level physics(29 %). In the wish list of courses to be open, high school level physics course was ranked first among seven options by 61 % of respondents. Also, there was some concurrence among respondents in opinion of the necessity for understanding introductory physics. Students felt difficulties in understanding it especially owing to the lack of problem solving skill and comprehension. They added that the sufficient explanation of core concepts should be the first action in the innovative plan. Most participants of pre-service physics teachers hoped to have the revised major curriculum which could help their understanding of high school level or introductory level of physics. However, there was a gap of opinions between the group of students with completion of the high school physics 1 & 2 course and those with non-completion of them. The approach of changing major curriculum with consideration of learners' needs was recommended because the number of students with completion of the high school physics course would probably be decreasing rapidly under these circumstances such as the application of new national curriculum, the reduction of the number of the elective courses in Korea Scholastic Aptitude Test and so on.

• Journal of The Korean Association For Science Education
• /
• v.31 no.5
• /
• pp.801-814
• /
• 2011

The purposes of this study were to understand what is physics teachers' perceptions of idealization and to explore their teaching experiences about idealization in their physics classes. In order to achieve these research purpose, we conducted in-depth interviews with ten Korean physics teachers. The interview data was transcribed and analyzed interpretively. The results are as follows: (1) Physics teachers are not familiar with the term of 'idealization' but they understand the meaning of idealization and ideal condition. (2) Physics teachers understand the necessity of explicit mentions of idealization and ideal conditions in physics classes. (3) Physic teachers adapt conceptions of idealization and ideal condition into their lectures, experimental classes and evaluation strategies. Thus, the results of this study can provide theocratical understanding of idealization. It will help develop teacher education programs and physics teaching strategies. This research also suggested follow-up research questions about idealization in the physics education field.

• Journal of The Korean Association For Science Education
• /
• v.32 no.8
• /
• pp.1295-1317
• /
• 2012

There has been disagreement on the importance of definitions in science education. Yager (1983) believes that one crisis in science education was due to the considerable emphasis upon the learning of definitions. Hobson (2004) disagrees with physics textbooks that do not provide general definition on energy. Some textbooks explain that "there is no completely satisfactory definition of energy" or they can only "struggle to define it." In general, imprecise definitions in textbooks (Bauman, 1992) and inaccuracies in definition provided by teachers (Galili & Lehavi, 2006) may cause alternative conceptions. Besides, there are at least four challenges in defining physical concepts: precision, circularity, context and completeness in knowledge. These definitional problems that have been discussed in The Feynman Lectures, may impede the learning of physical concepts. A meta-study approach is employed to examine about five hundreds journal papers that may discuss definitions in physics, problems in defining physical concepts and how they may result in alternative conceptions. These journal papers are mainly selected from journals such as American Journal of Physics, International Journal of Science Education, Journal of Research in Science Teaching, Physics Education, The Physics Teachers, and so on. There are also comparisons of definitions with definitions from textbooks, Dictionaries of Physics, and English Dictionaries. To understand the nature of alternative conception, Lee et al. (2010) have suggested a theoretical framework to describe the learning issues by synthesizing cognitive psychology and science education approaches. Taking it a step further, this study incorporates the challenges in semantics and epistemology, proposes that there are at least four variants of alternative conceptions. We may coin the term, 'alternative definitions', to refer to the commonly available definitions, which have these four problems in defining physics concepts. Based on this study, alternative definitions may result in at least four variants of alternative conceptions. Note that these four definitional problems or challenges in definitions cannot be easily resolved. Educators should be cognizant of the four variants of alternative conceptions which can arise from alternative definitions. The concepts of alternative definitions can be useful and possibly generalized to science education and beyond.

• Journal of Engineering Education Research
• /
• v.16 no.2
• /
• pp.50-57
• /
• 2013

The study to improve engineering students' performance in studying physics lacked despite of the importance of studying physics in engineering education. The cognitive belief and the motivational belief in studying physics had a strong effect on studying physics. The purpose of this study was to seek the educational way through comparing professors' expectations with students' beliefs about the cognitive belief and the motivational belief in studying physics. The cognitive belief in studying physics was considered as variables like 'knowledge', 'learning' and 'relation'. The motivational belief in studying physics was considered as variables like 'expectancy' and 'value'. It was the 'expectancy' that was the most different dimension between professors' expectations and students' beliefs. It means that students have little confidence in their abilities to study physics, though professors expect their students to be confident. Professor who teaches physics to engineering students recognize these differences, need to have interest in affective domains of beliefs to teach. In addition, there is need to teaching and learning strategies that can lead engineering students' beliefs about ability to perform the task, the purpose, importance, interesting for physics.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2008.12a
• /
• pp.112.2-112.2
• /
• 2008

• Nuclear Engineering and Technology
• /
• v.51 no.1
• /
• pp.190-197
• /
• 2019

W-K-TiC alloys with different titanium carbide concentrations (0.05, 0.1, 0.25, 0.5, 1, 2) wt.% were fabricated through Mechanical Alloying and Spark Plasma Sintering. The effects of the addition of nano-scaled TiC particles on the relative density, Vickers micro-hardness, microstructure, crystal information, thermal shock resistance, and tensile strength were investigated. It is revealed that the doped TiC nano-particles located at the grain boundaries. The relative density and Vickers micro-hardness of W-K-TiC alloys was enhanced with TiC addition and the highest Vickers micro-hardness is 731.55. As the TiC addition increased from 0.05 to 2 wt%, the room-temperature tensile strength raised from 141 to 353 MPa. The grain size of the W-K-TiC alloys decreased sharply from $2.56{\mu}m$ to 330 nm with the enhanced TiC doping. The resistance to thermal shock damage of W-K-TiC alloys was improved slightly with the increased TiC addition.

• Journal of The Korean Association For Science Education
• /
• v.18 no.2
• /
• pp.245-256
• /
• 1998

In this study, we discussed about the implications of the idealization, which take an important role in physics, to the physics education. First, understanding of the idealization help the physics learning itself. This is because that various types of idealizations are included in the physics terms and concepts, derivation processes of physics laws and formulas, and explanation of natural phenomena and problem solving activities. Second, understanding of the idealization can help the application of the physics world to the real world. That is, by understanding the extent and the limit of idealization used in physics world, physics students can understand the discrepancies between the real world and the physics world. And also, by modifying or eliminating the idealization, students can extend the extent of understanding about how predictions based on the idealization used in the physics world will change. To do this, we suggested the application of computer simulation program in physics laboratories. Third, idealization take an important role in the inquiry learning for students' originality. The activities of identifying or controlling the variables, as one of the principal factors of scientific inquiry, need the appropriate establishment of the ideal conditions. And to analyze the limiting case or practice the thought experiments for understanding the impossible situation in the real world, ideal conditions also are needed. This study discussed above three aspects with various concrete examples and, with Park et al.'s study (Park et al., 1998), present the theoretical basis for the study of students' and teachers' understanding the idealization.

• Nuclear Engineering and Technology
• /
• v.53 no.1
• /
• pp.164-171
• /
• 2021

The europium sorption on Tamusu clay was investigated by batch sorption experiments and spectroscopic study under the condition of strong ionic strength. The results demonstrated that europium sorption on Tamusu clay increased rapidly with pH value, but decreased with the ionic strength of solution increased. The europium sorption also increased in the presence of humic acid, especially at low pH value. The sorption could be fitted by Freundlich isotherm model and the europium sorption on clay was spontaneous and endothermic reaction. Besides, the result indicates that ion exchange was the main process at low pH value, while inner-sphere surface complexation dominated the sorption process at high pH value. The Backscatter electron scanning/Energy Dispersive Spectrometer(BSE/EDS) and the effect of Na for europium sorption results further suggested that europium sorption on Tamusu clay mainly competed with Na at low pH value. Overall, the results in this research were of significance to understand the sorption behavior of europium on the geological media under high ionic strength.