• Journal of The Korean Association of Information Education
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• v.25 no.6
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• pp.917-925
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• 2021

This study aims to specify a constructivism-based instructional method using a modular data analysis tool. The value and meaning of a modular data analysis tool have been examined to be applied in the national curriculum for artificial intelligence education and the process of cultivating problem-solving ability based on computational thinking. The modular data analysis tool visually expresses the cognitive thinking process that forms the schema in equilibrating through assimilation and adjustment. Artificial intelligence education has features that embody abstract knowledge and structure the data analysis module through the represented schema as a BlackBox implemented as an algorithm. Therefore, the value of the modular data analysis tool could be examined because it has the advantage of connecting the conceptual and implicit schema.

• Advances in aircraft and spacecraft science
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• v.9 no.5
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• pp.449-462
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• 2022

Space-telescopes placed in the Sun-Earth second Lagrange point (L2) observe the sky following a scan strategy that is usually based on a spin-precession motion. Knowing which regions of the sky will be more observed by the instrument is important for the science operations and the instrument calibration. Computing sky observation parameters numerically (discretizing time and the sky) can consume large amounts of time and computational resources, especially when high resolution isrequired.This problem becomesmore critical if quantities are evaluated at detector level instead of considering the instrument entire Field of View (FoV). In previous studies, the authors have derived analytic solutions for quantities that characterize the observation of each point in the sky in terms of observation time according to the scan strategy parameters and the instrument FoV. Analytic solutions allow to obtain results faster than using numerical methods as well as capture detailed characteristics which can be overseen due to discretization limitations. The original approach is based on the analytic expression of the instrument trace over the sky. Such equations are implicit and thusrequiresthe use of numeric solversto compute the quantities.In this work, a new and simpler approach for computing one ofsuch quantities(mean observation time) is presented.The quantity is first computed for pure spin motion and then the effect of the spin axis precession is incorporated under the assumption that the precession motion is slow compared to the spin motion.In this sense, this new approach further simplifies the analytic approach, sparing the use of numeric solvers, which reduces the complexity of the implementation and the computing time.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2230-2245
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• 2023

KANT (KAIST Advanced Nuclear Tachygraphy) is a PWR core simulator recently developed at Korea Advance Institute of Science and Technology, which solves three-dimensional steady-state and transient multigroup neutron diffusion equations under Cartesian geometries alongside the incorporation of thermal-hydraulics feedback effect for multi-physics calculation. It utilizes the standard Nodal Expansion Method (NEM) accelerated with various Coarse Mesh Finite Difference (CMFD) methods for neutronics calculation. For thermal-hydraulics (TH) calculation, a single-phase flow model and a one-dimensional cylindrical fuel rod heat conduction model are employed. The time-dependent neutronics and TH calculations are numerically solved through an implicit Euler scheme, where a detailed coupling strategy is presented in this paper alongside a description of nodal equivalence, macroscopic depletion, and pin power reconstruction. For validation of the steady, transient, and depletion calculation with pin power reconstruction capacity of KANT, solutions for various benchmark problems are presented. The IAEA 3-D PWR and 4-group KOEBERG problems were considered for the steady-state reactor benchmark problem. For transient calculations, LMW (Lagenbuch, Maurer and Werner) LWR and NEACRP 3-D PWR benchmarks were solved, where the latter problem includes thermal-hydraulics feedback. For macroscopic depletion with pin power reconstruction, a small PWR problem modified with KAIST benchmark model was solved. For validation of the multi-physics analysis capability of KANT concerning large-sized PWRs, the BEAVRS Cycle1 benchmark has been considered. It was found that KANT solutions are accurate and consistent compared to other published works.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1075-1083
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• 2000

The prediction of the inelastic behavior of the structure is an essential part of reliability assessment procedure, because most of the failures are induced by the inelastic deformation, such as creep and plastic deformation. During decades, there has been much progress in understanding of the inelastic behavior of the materials and a lot of inelastic constitutive equations have been developed. These equations consist of the definition of inelastic strain and the evolution of the state variables introduced to quantify the irreversible processes occurred in the material. With respect to the definition of the inelastic strain, the inelastic constitutive models can be categorized into elastoplastic model, unified viscoplastic model and separated viscoplastic model and the different integration methods have been applied to each category. In the present investigation, the generalized integration method applicable for various types of constitutive equations is developed and implemented into ABAQUS by means of UMAT subroutine. The solution of the non-linear system of algebraic equations arising from time discretization with the generalized midpoint rule is determined using line-search technique in combination with Newton method. The strategy to control the time increment for the improvement of the accuracy of the numerical integration is proposed. Several numerical examples are considered to demonstrate the efficiency and applicability of the present method. The prediction of the inelastic behavior of the structure is an essential part of reliability assessment procedure, because most of the failures are induced by the inelastic deformation, such as creep and plastic deformation. During decades, there has been much progress in understanding of the inelastic behavior of the materials and a lot of inelastic constitutive equations have been developed. These equations consist of the definition of inelastic strain and the evolution of the state variables introduced to quantify the irreversible processes occurred in the material. With respect to the definition of the inelastic strain, the inelastic constitutive models can be categorized into elastoplastic model, unified viscoplastic model and separated viscoplastic model and the different integration methods have been applied to each category. In the present investigation, the generalized integration method applicable for various types of constitutive equations is developed and implemented into ABAQUS by means of UMAT subroutine. The solution of the non-linear system of algebraic equations arising from time discretization with the generalized midpoint rule is determined using line-search technique in combination with Newton method. The strategy to control the time increment for the improvement of the accuracy of the numerical integration is proposed. Several numerical examples are considered to demonstrate the efficiency and applicability of the present method.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.75-87
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• 2007

Groundwater recharge rates were estimated and compared in a headwater catchment at the Gwangneung Supersite using three different methods: water-table fluctuation (WTF), mass balance, and hydrograph separation techniques. Data were obtained during the rainy season from June to September 2005. Two different WTF methods estimated the groundwater recharge rate as 25.9% and 23.6%. The mass balance calculation of chloride ions indicated recharge rates of 13.4% on average. Baseflow separation using chloride ion as a tracer from six storm hydrographs produced a 14.0% net baseflow rate on average. Because of the implicit assumption of a long-term steady state without storage change, recharge rates calculated by mass balance and hydrograph separation were smaller than those done with WTF methods, which include the amount of increased storage due to the water-level rise. Subsequently, the WTF method is superior to others in the estimation of groundwater recharge rate to comprehend the dynamic characteristics of the hydrologic cycle.

• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.1
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• pp.8-23
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• 1997

Steady and unsteady numerical simulations are conducted for the comparison with the experiments performed to investigate the ram accelerator flow field by using an expansion tube facility in Stanford University. Wavier-Stokes equations for chemically reacting flows are analyzed by fully implicit and time accurate numerical methods with Jachimowski's detailed chemistry model for hydrogen-air combustion involving 9 species and 19 reaction steps. Although the steady state numerical simulation shows a good agreement with the experimental schlieren and OH PLIF images for the case of $2H_2$＋$O_2$＋$17N_2$ fails in reproducing the combustion region behind the shock intersection point shown in the case of $2H_2$＋$O_2$＋$12N_2$ mixture. Therefore, an unsteady numerical simulation is conducted for this case and the result shows all the detailed flow stabilization process. From the result of unsteady numerical simulation, the experimental result seems to be an instantaneous state during the flow stabilization process. The combustion behind the shock intersection point is the result of a normal detonation formed by the intersection of strong oblique shocks that exist at early stage of the stabilization process. At final stage, the combustion region behind the shock intersection point disappears and the steady state result is retained. The time required for stabilization of the reacting flow in the model ram accelerator is found to be very long in comparison with the experimental test time.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.287-294
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• 2016

The whole design process drawing outputs from design planning is based on designers' intuitive ideas and differences in technical ability. However, every design professional agrees to the fact that such design process is filled with individuals' implicit acts or inherent intuition rather than following directions in a certain defined frame. If the design process based on such intuition and experience can start from the rational and scientific process, it would be possible to move more systematic design process to the next step. This study aims to examine what system of thinking are used by designers to conduct the design information process, by using the protocol analysis which is the representative qualitative study method of cognitive science, on designers' cognitive behaviors like the contents of the design sketch process which is the initial step of the kitchenware development process, in order to understand professionals' and non-professionals' design application direction. Thus, the scope of this paper would be limited to "the initial protocol analysis on kitchenware" and "encoding of the analysis on thinking" in the qualitative study that can be the most basic to understand the design cognitive science. As a procedure to solve this study question, it aimed to seek for the product development flow and the educational effect by considering the preceding researches and also re-interpreting cognitive thinking in systematic methods.

• Quality Improvement in Health Care
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• v.1 no.1
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• pp.96-108
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• 1994

Background: An appropriate use of hospital beds can improve productivity of hospital significantly. The authors' previous study revealed that approximately one third of Korean hospital bed days and one sixth of admissions were inappropriately used, when it was measured by Appropriateness Evaluation Protocol(AEP) and Delay Tool modified into Korean situation by the authors. This study aims to evaluate applicability of the instruments in a new hospital. More specifically the study aims to measure appropriateness of the instruments used by newly trained nurse reviewers at a new hospital setting. Methods: In order to evaluate applicability of these instruments, agreement rates of the scores recorded by newly trained nurse reviewers with by skilled nurse reviewer and also compared with the scores recorded by physician's implicit decision were assessed. Agreement rates were derived from concurrent application of AEP and Delay Tool to 52 admissions and 104 patient days from internal medicine, pediatrics, and general surgery of one university hospital. Overall agreement rate, specific nonacute agreement rate, and kappa statistics were used to indicate level of agreement. Results: Overall agreement rates on appropriateness between newly trained nurse reviewers and skilled nurse reviewer were 100% in admission and 98% in bed days. Overall agreement rates on reason for inappropriateness between newly trained nurse reviewers and skilled nurse reviewer were 96% in admission and 91% in bed days. Overall agreement rates between newly trained nurse reviewers and physician reviewer were 86% in admission and 87% in bed days. Conclusion: Results indicated that AEP and Delay Tool were applicable to a new hospital in detecting inappropriate utilization of beds and reasoning of the inappropriateness. These instruments could contribute to enhance efficiency of hospital use, through continuous monitoring of level of inappropriate hospital use at national or individual hospital level.

• The Journal of the Korea Contents Association
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• v.18 no.5
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• pp.545-553
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• 2018

As the share of leisure culture increases these days, expectations are rising for the high quality of culture while increasing interest in leisure and tourism. The percentage of the population going on weekend trips to broaden the horizons of elementary, middle and high school students has continued to rise in proportion to the expectations for cultural enjoyment. We expect that visitors' weekend family activities will include relaxing, playing and educational purposes. Recent educational programs have moved from the past where only children were allowed to be onsite, to a shared style in which parents can engage in educational activities, potentially leading to the implicit involvement of family ties and family elasticity. The effects of education are not expressed by the period that ends in a single moment of experience, but by the continuity of training and experience. The same holds true for family affinity, communication and empathy. Providing opportunities for family experience and education is a national responsibility for broken family and restoring solidarity with the growing number of single-person households. Furthermore, it is a duty of museums and galleries today, and it is necessary to come up with methods to enhance family solidarity and family affinity. In particular, it is imperative to develop and provide educational programs for educational purposes at the Education Museum, and to develop " education for family " at the social level. This paper aims to analyze the results of all family participating education programs provided by family education programs at the Education Museum through family surveys and interviews, and to enhance the activation of family types education programs more actively.

• Journal of Korean Society of Steel Construction
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• v.23 no.5
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• pp.535-546
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• 2011

In this paper, semi-rigid elasto-plastic post-buckling analysis of a space frame was performed using various explicit arc-length methods. Various explicit arc-length methodsand a large-deformation and small-strain elasto-plastic 3D space frame element with semi-rigid connections and plastic hinges were developed. This element can be appliedto both explicit and implicit numerical algorithms. In this study, the Dynamic Relaxation method was adopted in the predictor and corrector processesto formulate an explicit arc-length algorithm. The developed "explicit-predictor" or "explicit-corrector" were used in the elasto-plastic post-buckling analysis. The Eulerian equations for a beam-column with finite rotation, which considers the bowing effects, were adopted for the elastic system and extended to theinelastic system with a plastic hinge concept. The derived tangent stiffness matrix was asymmetrical due to the finite rotation. The joint connection elements were introduced for semi-rigidity using a static condensation technique. Semi-rigid elasto-plastic post-buckling analyses were carried out to demonstrate the potential of the developed explicit arc-length method and advanced space frame element in terms of accuracy and efficiency.