• Nuclear Engineering and Technology
• /
• 제48권3호
• /
• 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.

• 한국환경과학회지
• /
• 제25권1호
• /
• 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.

• 방사성폐기물학회지
• /
• 제16권4호
• /
• 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.

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 2009년도 IWAIT
• /
• 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
• /
• 제52권4호
• /
• 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
• /
• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
• /
• 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
• /
• 제54권7호
• /
• 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
• /
• 제38권3호
• /
• 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.

• 과학교육연구지
• /
• 제37권2호
• /
• pp.374-388
• /
• 2013

이 연구에서는 교사 양성을 위한 전공 교육과정에 관하여 물리교육과 재학생의 인식을 조사하고 개선 방안을 탐색하고자 하였다. 이를 위하여 한 사범대학의 물리교육과에 재학 중인 3학년 15명, 4학년 13명을 대상으로 설문을 실시하였다. 응답자 중 24명(86 %)이 고등학교에서 물리 I을 이수하였고, 22명(79%)은 대학수학능력시험에서 물리 I과목에 응시하였다. 설문 결과에 따르면 본인에게 현재 가장 필요한 영역으로 고등학교 물리 수준의 이해(36%), 일반물리학 수준의 이해(29 %) 등이 많이 선택되었다. 또 가장 필요한 신설 강좌로 응답자의 61 %(17명)가 고등학교 물리 수준의 강좌를 지목하였다. 아울러 일반물리학에 대한 학습이 필요하다는 점에 있어 비교적 일관된 의견을 보였다. 구체적으로 살펴보면 재학생들은 연습 문제 풀이가 어렵고 이해가 부족하여, 일반물리학 학습 과정에서 어려움을 겪는다고 응답하였다. 일반물리학 강좌의 개선 방안으로는 핵심 개념 이해를 위한 충분한 설명을 가장 우선시하였다. 이처럼 설문에 참여한 예비 교사들은 대체로 고교 물리 및 일반물리학의 이해를 도와줄 수 있는 방향으로 대학의 전공 교육과정이 개정되기를 희망하였다. 다만 고등학교에서 물리 II를 이수한 학생과 전혀 이수하지 않은 학생 사이에 의견 차이가 있었다. 새 교육과정의 적용 및 대학수학능력시험의 선택 과목 축소 등에 따라 향후 고등학교에서 물리를 이수하고 물리교육과에 입학하는 학생이 더욱 줄어들 것으로 예상되기 때문에, 학습 수요를 고려하여 전공 교육과정을 개정하는 방안을 다각적으로 검토할 필요가 있다.

• 한국과학교육학회지
• /
• 제29권5호
• /
• pp.541-551
• /
• 2009

본 연구에서는 6명의 예비 과학교사들이 30주간 핵물리 관련 URP 프로그램에 참여하면서 어떠한 경험을 하며 이러한 경험이 그들의 과학 지식 및 과학 탐구 과정, 과학자에 대한 인식, 그리고 그들이 자신의 진로를 탐색하는 데 어떠한 영향을 주는지에 대해 알아보았다. 참여 학생들에 대한 심층적 이해를 위해, 실험과정 및 토의과정에의 참여 관찰 및 필드노트, 개별 심층 면담 및 그룹면담, 연구일지 등이 주요 자료로 수집되었다. 연구 결과, 참여 학생들은 과학이론이 생성되기까지의 과정에서 드러나는 특성들, 즉 계속적인 반복의 과정으로 시간과 인내를 요구하며, 창의성과 공동 연구의 중요성 등을 인식하게 되었다. 또한 전형적인 과학자의 이미지에 대해 다소 변화된 부분이 있었다. 뿐만 아니라 그들은 URP 프로그램 참여를 통해 물리학에 대해 더욱 관심을 갖게 됨과 동시에 물리학에 대한 자신의 적성을 확인하는 기회를 갖게 되었다.