• Korean Journal of Human Ecology
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• v.18 no.3
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• pp.583-595
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• 2009

The study was to see if the perceptions of pre-service kindergarten teacher toward the education of children's fundamental habit would show different characteristics based on their school type, education learning experience, and practicum experience. Subjects were 200 students majoring in early childhood education who were attending 3-year colleges and 4-year universities in Jellabuk-do and Daejeon. Preceding researches were referenced to develop questionnaire for the research method. The collected data was analyzed through t-test and Chi-square test. The followings are results: First, the interest in education showed significant difference in school type, but not significant difference in education learning experience and practicum experience. Second, the recognition in educational goal showed significant difference in practicum experience, but not significant difference in school type and education learning experience. the educational content showed significant difference in education learning experience, but not in school type and practicum experience. the recognition in educational principal showed significant difference in school type, but not significant difference in education learning experience and practicum experience. the recognition in educational method showed no significant difference in school type, education learning experience and practicum experience. Third, the recognition in educational hardship toward teaching showed significant difference in school type, education learning experience and practicum experience. The results of study would provide the righteous cognitive establishment of children's fundamental habit education and serve the appropriate guidelines being professor for our perspective kindergarten teachers. Also, they would be utilized as basic information to plan the direction of children's fundamental habit education to develop the program of children's life guidance.

• Journal of Biosystems Engineering
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• v.25 no.6
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• pp.489-496
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• 2000

This study was conducted in order to find an ideal working fluid kind and a proper filling amount in the heat pipe as well as an inclined angle of heat pipe when they are placed to recover exhaust gas heat in the hot air heater. Followings are the findings of this research. 1. Of the four different working fluids-gasoline kerosene distilled water and acetone-acetone filled heat pipe showed the best performance giving out more homogeneous temperature profile on the radiating part than the kerosene and gasoline heat pipe an carrying out heat transmitting function better than the distilled water heat pipe by 10~2$0^{\circ}C$ higher on the radiating part. Acetone would be a good choice for recycling of exhaust gas heat in the hot air heater. 2. Of the filling amount of working fluid inside the heat pipes dry-out situations possible caused by insufficient filling were found in the filling amount of 5, 7.5 and 10% heat pipes as heat supply rate increases gradually in the range of 50 to 15kJ/sec. but no dry-out and stabilized heat transmitting performance occurred in the heat pipes of 12.5 and 15% filling at the same heat supply rate. It recommends that filling amount shall exceed 12.5% at least with the working fluids of this experiment. 3. The test revealed that the heat transmitting performance of heat pipe was more affected by filling amount rather than inclined angle.

• Journal of the Korean Institute of Educational Facilities
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• v.21 no.3
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• pp.29-36
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• 2014

Properties of school foundation are divided into fundamental property for education and fundamental property for profit. As school sites and teachers used for educational and study activities of students, fundamental property for education includes practice sites, farms and support research attached facilities in addition to school facilities. According to the Clause 1 of Article 4 of the University Foundation and Management Regulation and the Attached Table 2 of the Same Regulation, dormitory is classified as property for education(non-profit). In other words, there is no need to create profit for dormitory management. It is supposed that there are little regional differences in construction cost of dormitory with general specifications. In this case, boarding fees of university dormitories should make no difference. This study analyzed boarding fees, depending on regional factors(Seoul, Gyeonggi-do, metropolitan cities and provinces), and depending on foundation subjects(national public university and private university), classes(four-year university and college) and principal schools-branch schools. The result of One-Way ANOVA showed that Seoul showed the highest average boarding fee and it was followed by Gyeonggi-do, metropolitan cities and provinces. Also, the average boarding fees of private universities and four-year universities were higher than national public universities and than colleges, respectively. In addition, branch school's boarding fee was higher than principal school's. Additionally, this study extracted a model using the hedonic model to see how various characteristics such as region, foundation subject and class influence the boarding fee. This study would serve as fundamental research on the boarding fee. Thus far, there have been difficulties in obtaining accurate data and analyzing boarding fees, since there is no open data about dormitories and it isn't mandatory to open it, but it is anticipated that this would be used as fundamental research for estimating and analyzing boarding fees of many universities in the future.

• Toxicological Research
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• v.35 no.3
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• pp.215-224
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• 2019

As various populations are rapidly becoming an aging society worldwide and interest in health issues has increased, demand for functional foods including herbal products has increased markedly to maintain a healthy state which has led to safety issues about their intake as an inevitable result. The objective of this study was to identify the safety profile of a Korean red ginseng and Salvia plebeia R. Br. extract mixture (KGC-03-PS) which is a valuable ingredient that can be used as a functional food. In the present study, the subacute oral toxicity and bacterial reverse mutagenicity of KGC-03-PS were evaluated. Sprague Dawley rats were administered KGC-03-PS orally for 28 days by gavage. Daily KGC-03-PS dose concentrations were 0, 500, 1,000, or 2,000 mg/kg body weight (bw) per day. Bacterial reverse mutation test with KGC-03-PS dose levels ranging from 312.5 to $5,000{\mu}g/plate$ was carried out by OECD test guideline No. 471. Five bacterial strains (Salmonella typhimurium TA98, TA100, TA1535, TA1537, and Escherichia coli WP2) were tested in the presence or absence of metabolic activation by plate incorporation method. There were no toxicological effects related with test substance in the clinical evaluation of subacute oral toxicity test including clinical signs, body weight, and food consumption. Moreover, no toxicological changes related to KGC-03-PS were observed in the hematological and serum biochemical characteristics as well as in the pathological examinations, which included organ weight measurements and in the gross- or histopathological findings. KGC-03-PS did not induce an increase in the number of revertant colonies in all bacterial strains of the bacterial reverse mutation test. The no-observed-adverse-effect level of KGC-03-PS is greater than 2,000 mg/kg bw/day, and KGC-03-PS did not induce genotoxicity related to bacterial reverse mutations under the conditions used in this study.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.36-48
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• 2022

As a valid numerical method to obtain a high-resolution result of a flow field, computational fluid dynamics (CFD) have been widely used to study coolant flow and heat transfer characteristics in fuel rod bundles. However, the time-consuming, iterative calculation of Navier-Stokes equations makes CFD unsuitable for the scenarios that require efficient simulation such as sensitivity analysis and uncertainty quantification. To solve this problem, a reduced-order model (ROM) based on proper orthogonal decomposition (POD) and machine learning (ML) is proposed to simulate the flow field efficiently. Firstly, a validated CFD model to output the flow field data set of the rod bundle is established. Secondly, based on the POD method, the modes and corresponding coefficients of the flow field were extracted. Then, an deep feed-forward neural network, due to its efficiency in approximating arbitrary functions and its ability to handle high-dimensional and strong nonlinear problems, is selected to build a model that maps the non-linear relationship between the mode coefficients and the boundary conditions. A trained surrogate model for modes coefficients prediction is obtained after a certain number of training iterations. Finally, the flow field is reconstructed by combining the product of the POD basis and coefficients. Based on the test dataset, an evaluation of the ROM is carried out. The evaluation results show that the proposed POD-ROM accurately describe the flow status of the fluid field in rod bundles with high resolution in only a few milliseconds.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.148-163
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• 2021

Timely fault identification is important for safe and reliable operation of the electric valve system. Many research works have utilized different data-driven approach for fault diagnosis in complex systems. However, they do not consider specific characteristics of critical control components such as electric valves. This work presents an integrated shallow-deep fault diagnostic model, developed based on signals extracted from DN50 electric valve. First, the local optimal issue of particle swarm optimization algorithm is solved by optimizing the weight search capability, the particle speed, and position update strategy. Then, to develop a shallow diagnostic model, the modified particle swarm algorithm is combined with support vector machine to form a hybrid improved particle swarm-support vector machine (IPs-SVM). To decouple the influence of the background noise, the wavelet packet transform method is used to reconstruct the vibration signal. Thereafter, the IPs-SVM is used to classify phase imbalance and damaged valve faults, and the performance was evaluated against other models developed using the conventional SVM and particle swarm optimized SVM. Secondly, three different deep belief network (DBN) models are developed, using different acoustic signal structures: raw signal, wavelet transformed signal and time-series (sequential) signal. The models are developed to estimate internal leakage sizes in the electric valve. The predictive performance of the DBN and the evaluation results of the proposed IPs-SVM are also presented in this paper.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1534-1539
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• 2004

The objective of this study is to simulate the etching characteristics with oscillation angle for the optimization of etching system. The etching characteristics were analyzed under different etching conditions. The spray characteristics were measured by Phase Doppler Anemometer (PDA). The correlation between the spray characteristics and the etching characteristics was investigated and used for fundamental data to simulate the etching characteristics with oscillation angle. The smaller coefficient of variation, the more uniform etching characteristic distribution became. It was found that numerical predictions of etching factor generally agreed well with the measured results with distance from nozzle tip. Oscillation leads to decrease of etching factor and increase of uniformity.

• Steel and Composite Structures
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• v.37 no.4
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• pp.391-404
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• 2020

Human-induced vibration could present a serious serviceability problem for large-span and/or lightweight floors using the high-strength material. This paper presents the results of heel-drop, jumping, and walking tests on a large-span composite steel rebar truss-reinforced concrete (CSBTRC) floor. The effects of human activities on the floor vibration behavior were investigated considering the parameters of peak acceleration, root-mean-square acceleration, maximum transient vibration value (MTVV), fundamental frequency, and damping ratio. The measured field test data were validated with the finite element and theoretical analysis results. A comprehensive comparison between the test results and current design codes was carried out. Based on the classical plate theory, a rational and simplified formula for determining the fundamental frequency for the CSBTRC floor is derived. Secondly, appropriate coefficients (β_rp) correlating the MTVV with peak acceleration are suggested for heel-drop, jumping, and walking excitations. Lastly, the linear oscillator model (LOM) is adopted to establish the governing equations for the human-structure interaction (HSI). The dynamic characteristics of the LOM (sprung mass, equivalent stiffness, and equivalent damping ratio) are determined by comparing the theoretical and experimental acceleration responses. The HSI effect will increase the acceleration response.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.7
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• pp.17-22
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• 2006

Potential application topics of KOMPSAT-3 image in the field of precision agriculture are suggested. The topics can be categorized as fundamental and applied ones that have contents of static and dynamic characteristics respectively. As fundamental topics, precision information of agriculture that is related to farmland and its crop attributes, precision information of rural infrastructure that is related to rural village and its facilities, precision information of stream environment that is related to rural water resources and its facilities, and precision information of eco-environment that is especially related to riparian ecology and environmental status are included. As applied topics, precision rural water resources that has thematic contents of continuous and event-based runoff, spatial and temporal soil moisture and evapotranspiration, precision agricultural watershed environment that has the contents of spatial and temporal soil loss, sediment and pollutants transport, and precision temporal and spatial crop growth that has the contents of temporal crop texture, spectral reflectance, leaf area index, spatial crop protein information.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.4
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• pp.401-410
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• 2008

The natural frequency of a beam plays an important role in not only vibration analysis but also understanding its dynamic characteristics. It is complicated to analyse the natural frequency of a stepped beam with discontinuously varying section. Approximate analysis methods such as Rayleigh-Ritz method, FEM, etc. are frequently used for the vibration analysis of stepped beams. In such a case, accuracy of these methods depends upon the number of partitioned elements, the number of the iterations in calculation and the assumed mode shape. This study presents an approximate analysis method for the fundamental natural frequency analysis of stepped cantilever beam, using equivalent beam transformation technique. Validity and usefulness are verified by comparing the proposed method with FEM for several example problems.