• Nuclear Engineering and Technology
• /
• v.48 no.3
• /
• pp.711-718
• /
• 2016

Steady-state operation of a fusion power plant requires external current drive to minimize the power requirements, and a high fraction of bootstrap current is required. One of the external sources for current drive is lower hybrid current drive, which has been widely applied in many tokamaks. Here, using lower hybrid simulation code, we calculate electron distribution function, electron currents and phase velocity changes for two options of demonstration reactor at the launched lower hybrid wave frequency 5 GHz. Two plasma scenarios pertaining to two different demonstration reactor options, known as pulsed (Option 1) and steady-state (Option 2) models, have been analyzed. We perceive that electron currents have major peaks near the edge of plasma for both options but with higher efficiency for Option 1, although we have access to wider, more peripheral regions for Option 2. Regarding the electron distribution function, major perturbations are at positive velocities for both options for flux surface 16 and at negative velocities for both options for flux surface 64.

• Journal of Environmental Science International
• /
• v.25 no.1
• /
• pp.67-83
• /
• 2016

In order to improve the prediction of the regional air quality modeling in the Seoul metropolitan area, a sensitivity analysis using two PBL and microphysics (MP) options of the WRF model was performed during four seasons. The results from four sets of the simulation experiments (EXPs) showed that meteorological variables (especially wind field) were highly sensitive to the choice of PBL options (YSU or MYJ) and no significant differences were found depending on MP options (WDM6 or Morrison) regardless of specific time periods, i.e. day and night, during four seasons. Consequently, the EXPs being composed of YSU PBL option were identified to produce better results for meteorological elements (especially wind field) regardless of seasons. On the other hand, the accuracy of all simulations for summer and winter was somewhat lower than those for spring and autumn and the effect according to physics options was highly volatile by geographical characteristics of the observation site.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.16 no.4
• /
• pp.431-439
• /
• 2018

Less mature nuclear reactor technologies are characterized by a greater uncertainty due to insufficient detailed design information, operational data, cost information, etc., but the expected performance characteristics of less mature options are usually more attractive in comparison with more mature ones. The greater uncertainty is, the higher economic risks associated with the project realization will be. Within a comparative evaluation of less and more mature nuclear reactor technologies, it is necessary to apply economic risk measures to balance judgments regarding the economic performance of less and more mature options. Assessments of any risk metrics involve calculating different characteristics of probability distributions of associated economic performance indicators and applying the Monte-Carlo method. This paper considers the applicability of statistical risk measures for different economic performance indicators within a trial case study on a comparative evaluation of less and more mature unspecified LWRs. The presented case study demonstrates the main trends associated with the incorporation of economic risk metrics into a comparative evaluation of less and more mature nuclear reactor technologies.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2009.01a
• /
• pp.834-837
• /
• 2009

Augmented Reality (AR) is a useful technology for various industrial systems. This paper suggests a new playground system which uses markerless AR technology. We developed a virtual playground system that can learn physics and kinematics from the physical play of people. The virtual playground is a space in which real scenes and CG are mixed. As for the CG objects, physics of the real world is used. This is realized by a physics engine. Therefore it is necessary to analyze information from cameras, so that CG reflects the real world. Various games options are possible using real world images and physics simulation in the virtual playground. We think that the system is effective for education. Because CG behaves according to physics simulation, users can learn physics and kinematics from the system. We think that the system can take its place in the field of education through entertainment.

• Nuclear Engineering and Technology
• /
• v.52 no.4
• /
• pp.689-699
• /
• 2020

In this work, new multi-recycling options of TRU nuclides using PWR fuel assemblies comprised of MOX and FCM (Fully Ceramic Micro Encapsulated) fuels are suggested and neutronically analyzed. These options do not use a fully recycling of TRU but a partial recycling where TRUs from MOX fuels are recycled while the ones from FCM fuels are not recycled due to their high consumption rate resulted from high burnup. In particular, additional external TRU feed in MOX fuels for each cycle was considered to significantly increase the TRU consumption rate and the finally selected option is to use external TRU and enriched uranium feed as a makeup for the heavy metal consumption in MOX fuels. This hybrid external feeding of TRU and enriched uranium in MOX fuel was shown to be very effective in significantly increasing TRU consumption rate, maintaining long cycle length, and achieving negative void reactivity worth during recycling.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.1744-1749
• /
• 2006

Line-scan SLS of thin Si films permits the attainment of low-defect-density Si films with a directionally solidified microstructure. This paper deals with: (1) identifying and examining the structural defects that are found in the resultant material, (2) how the spatial variations in the type and density of the observed defects may potentially affect the overall uniformity of the resulting devices, and (3) some technical options that may be applied in order to potentially alleviate the situation.

• Nuclear Engineering and Technology
• /
• v.54 no.7
• /
• pp.2650-2659
• /
• 2022

The dense granular flow spallation target is a new target concept proposed for an Accelerator-Driven Sub-critical (ADS) system. In this paper, the beam-target configurations of a tungsten granular flow target for the ADS with a thermal power of 1 GW is explored. The beam profile options using different scanning methods are discussed. The critical geometry parameters are adjusted to investigate the performance of the granular target from the aspects of neutron efficiency, stability and temperature distribution in target medium. To figure out how the target under accident conditions would behave, different clogging conditions are induced in the simulation. The dynamic processes are analyzed and some important parameters such as abnormal temperature rise and beam cutoff time window are obtained. The response of the sub-critical reactor to a clogging accident is also investigated. It is indicated that the monitoring of the granular flow by the neutron detectors in the sub-critical core will be effective.

• Nuclear Engineering and Technology
• /
• v.38 no.3
• /
• pp.225-230
• /
• 2006

With the advent of inexpensive computing power over the past two decades, applications of Monte Carlo radiation transport techniques have proliferated dramatically. At Los Alamos, the Monte Carlo codes MCNP5 and MCNPX are used routinely on personal computer platforms for radiation shielding analysis and dosimetry calculations. These codes feature a rich palette of variance reduction (VR) techniques. The motivation of VR is to exchange user efficiency for computational efficiency. It has been said that a few hours of user time often reduces computational time by several orders of magnitude. Unfortunately, user time can stretch into the many hours as most VR techniques require significant user experience and intervention for proper optimization. It is the purpose of this paper to outline VR strategies, tested in practice, optimized for several common radiation shielding tasks, with the hope of reducing user setup time for similar problems. A strategy is defined in this context to mean a collection of MCNP radiation transport physics options and VR techniques that work synergistically to optimize a particular shielding task. Examples are offered in the areas of source definition, skyshine, streaming, and transmission.

• 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.29 no.5
• /
• pp.541-551
• /
• 2009

This study aimed to investigate the effect of pre-service science teachers' experiences in nuclear physics research on their understanding of scientific inquiry process and career planning. The thirty-week URP (Undergraduate Research Participation) program was designed with the participation of six pre-service science teachers. Data sources included in-depth interviews with the individual teachers, group discussions, participant observations with field notes over the weeks, journals and lab logs, etc. Results indicated that the teachers perceived the complex and repetitive nature of the science research process, the importance of scientists' creativity and collaboration, etc. Their typical impressions of scientists has also more or less changed. In addition, the teachers had opportunities to confirm their aptitude in physics and to explore their career options in physics-related fields.