• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.3
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• pp.238-242
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• 2003

Reclaimed tidal areas for rice cultivation are irrigated with salt mixed water when there is severe drought. Therefore, we identified the critical concentration of saline water for rice growth on a reclaimed saline soil in Korea. The experiment was conducted at the Kyehwado substation of the National Honam Agricultural Experiment Station (NHAES) during 2001-2002. Two experimental fields with 0.1-0.2% for low soil salinity and 0.3-0.4% for medium soil salinity levels were used. The experiment involved four levels of salt solution mixed with sea water (at 0.1, 0.3, 0.5, 0.7%) compared with a control using tap water in a split-plot design with three replicates. Saline solution was applied only two times at seedling stage (10 DAT and 25 DAT) for 5 days. Gyehwabyeo and dongjinbyeo, japonica rice varieties, were used in this experiment. Plant height and number of tillers sharply decreased in the 0.5% saline water in low soil salinity level and 0.1% in medium soil salinity level. For yield components, panicle number per unit area and percentage of ripened grain dramatically decreased in the 0.5% saline water in low soil salinity and 0.1% in medium soil salinity level. But 1,000-grain weight of brown rice decreased sharply in the 0.5% saline water in low soil salinity and 0.3% in medium soil salinity, indicating that this component was not much affected unlike other yield components. Milled rice yield decreased significantly with saline water level in both low and medium soil salinity. In the 0.7% low saline soil, the yield index was only 36% compared with the control. In medium soil salinity, even the control plot showed only 62% yield index compared with the control in the low soil salinity treatment. Results indicated that the critical concentration of saline water for rice growth in terms of economical income of rice production was 0.5% in low soil salinity and tap water in medium soil salinity.

• Korean Journal of Weed Science
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• v.4 no.2
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• pp.130-134
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• 1984

This experiment was conducted to know critical sowing depth and emergence day under different sowing depth at Crop Experiment Station, Suweon, in 1982. Tested weed species were Sagittaria pygnaea, Eleocharis kuroguwai, Cyperus serotinus and Potamageton distinetus, sowing depth of weeds were 5cm, 10cm, 15cm, 20cm and 25cm Critical emergence sowing depth of S. pygnaea, E. kuroguwai was 15cmand C. serotinus was 20cm sowing depth while P. distintus was 25cm sowing depth. Average emergence days under 5cm sowing depth for E. kurogwai, S. pygmaea, P. distintus and C. serotinus was 27.8 days, 14.1 days, 13.6 days and 7.3 days. While, relationships between sowing depth and day to emergence was positively correlated. Gernination percent of weeds under Critical emergence sowing depth, S. pygmaea, E. kurogwai and, P. distinctus was 57%, 67%, 80%, but C. serotinu.s was all died.

• Journal of Science Education
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• v.44 no.2
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• pp.225-239
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• 2020

This study aims to analyze the characteristics of reflective thoughts of students during experiments in general physics experiments. The participants were 32 college students, they submitted 10 experiment reports including answers to questions for reflective thinking. The results were as follows: First, students show reflective thinking broadly in the experiment, levels were followed by practical reflection, technical reflection, and critical reflection. Also, they actively accepted the knowledge related to experiments, but were passive in connecting new knowledge and experiences obtained through the experiments or forming new questions. Second, the reflective thinking of students show high correlation with experiments related to prior knowledge or the easy-to-understand process. Third, through the qualitative analysis of open-ended questions, it was confirmed that technical reflection occurs in individual evaluation, practical reflection in group evaluation, and practical reflection and critical reflection in improvement proposal. While the students' reflective thinking were superficial or mainly functional, however, they recursively examined the learning contents and the experimental process concurrently.

• Plant Resources
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• v.5 no.2
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• pp.155-160
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• 2002

The heading date is known to be controlled by two kinds of genetic constituent, photosensitivity and basic vegetable phase. For the latter, the effect of temperature in early growth period is critical to determine the shortness of vegetative growth periods in plant's life. A phytotron experiment on 55 rice cultivars, consisting of two ecotypes of rices, indica and japonica, was conducted at high and low temperature treatments at early growth stage to investigate the possible role of plant growth stimulus by high temperature to associate with shortening of heading date. The high temperature during the early growth stage stimulated the rice growth as measured by plant height with much difference of the growth response between indica and japonica. The conclusive finding that these growth stimulus in early growth stage was highly correlated with the acceleration of heading is, more or less, correlated with the heading of the late growth stage although we could not conclude the genes for early plant growth stimulus by high temperature is the same genes as the genes for accelerating of heading in the late growth stage of plants.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.14-18
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• 2020

Korea Atomic Energy Research Institute (KAERI) has carried out various neutronics experiments in the commissioning stage of the Jordan Research and Training Reactor (JRTR), and this paper introduces the results of first criticality prediction and experiment for the JRTR. The Monte Carlo Code for Advanced Reactor Design and analysis (McCARD) with the ENDF/B-VII.0 nuclear library was used for prediction calculations in the process of the first criticality approach, which was performed to provide reference for the first criticality experiment. In the experiment, fuel loading was carried out by measuring the inverse multiplication factor (1/M) to predict the number of fuel assemblies at the first criticality, and the first critical was reached on April 25, 2016. Comparing the first criticality prediction and experiment, the calculated and measured CAR (Control Absorber Rod) heights for the first criticality were 575 mm and 570.5 mm, respectively, that is, the difference between the two results was approximately 5 mm. From this result, it was confirmed that JRTR manufacturing and various experiments had successfully progressed as designed.

• The Journal of the Korea Contents Association
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• v.18 no.4
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• pp.406-415
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• 2018

The purpose of this study was to analyze the effectiveness of Capstone Design Program on creative leadership, problem solving ability and critical thinking of nursing students. The subjects of 18 experiment groups taking course in nursing capstone design of U university in P city and 20 control group of K university in G city. Data were collected before and after nursing capstone design class using self-reported questionnaire. Students Creative leadership and problem solving ability showed significant showed improvements after the Capstone Design Program. Creative leadership, Problem solving ability and critical thinking was positively correlated and then Problem solving abilities appeared to be higher improved critical thinking. Therefore, it is recommended that sufficient repetitive practice is to be made in order to improve Creative Leadership, Problem solving ability and critical thinking.

• Nuclear Engineering and Technology
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• v.52 no.4
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• pp.755-763
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• 2020

The critical flow phenomenon has been studied because of its significant effect for design basis accidents in nuclear power plants. Transition points from thermal non-equilibrium to equilibrium are different according to the geometric effect on the critical flow. This study evaluates the uncertainty parameters of the critical flow model for analysis of DBA (Design Basis Accident) with the MARS-KS (Multi-dimensional Analysis for Reactor Safety-KINS Standard) code used as an independent regulatory assessment. The uncertainty of the critical flow model is represented by three parameters including the thermal non-equilibrium factor, discharge coefficient, and length to diameter (L/D) ratio, and their ranges are determined using large-scale Marviken test data. The uncertainty range of the thermal non-equilibrium factor is updated by the MCDA (Model Calibration through Data Assimilation) method. The updated uncertainty range is confirmed using an LBLOCA (Large Break Loss of Coolant Accident) experiment in the LOFT (Loss of Fluid Test) facility. The uncertainty ranges are also used to calculate an LBLOCA of the APR (Advanced Power Reactor) 1400 NPP (Nuclear Power Plants), focusing on the effect of the PCT (Peak Cladding Temperature). The results reveal that break flow is strongly dependent on the degree of the thermal non-equilibrium state in a ruptured pipe with a small L/D ratio. Moreover, this study provides the method to handle the thermal non-equilibrium factor, discharge coefficient, and length to diameter (L/D) ratio in the system code.

• Journal of The Korean Association For Science Education
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• v.9 no.1
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• pp.75-89
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• 1989

Secondary schools in Korea have been faced with several critical problems with regard to science education. Among them one of the most fundamental problems is associated with laboratory-based science education. There fore as a part of research project for the improvement of science education in secondary schools, this study had its abjectives to inquire into the following areas related to laboratory experiment. ${\circ}$Survey and analysis of theoretical backgrounds for science teaching focused on laboratory experiments. ${\circ}$Status survey of experiment-based science teaching in high schools. ${\circ}$Development of model for improving experiment-based science teaching. In order to fulfill these objectives this study used methods of eiterature review, survey, and interviews. The major finding are as follows : ${\circ}$Some topic for laboratory experiments as oppeared in the textbooks are not appropriate in the light of sience curricular operations in high schools. ${\circ}$In some schools equipments and facilities of school laboratories are for from sufficiency. ${\circ}$Laboratory experiments are not financially supportel for ideal science teach in both middle schools and high schools. These are not on exhaustive list of findings from this study More finding and teaching model for improvement of science education are also described in this paper.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.2
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• pp.136-144
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• 2009

This paper focuses on the attempt to manual application for optimization structural scale of stone and Gabion at the closing gap of sea dike. The manual was developed through hydraulic model experiment that measured the critical velocity of sill-crest, bottom protection and dam-face at the final closure of Saemangeum sea dike, and through the comparison and verification of critical velocity for each scale calculated by existing empirical formula. Also, the critical velocity when rocks are used together with gabion is measured to add to the manual, which is an initial attempt that had not been executed before. The manual proposes the appropriate structural scale according to the measured critical velocity per day during the final closure period of Saemangeum sea dike, and its application was appraised highly after the completion of the final closing.

• Journal of The Korean Association For Science Education
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• v.33 no.7
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• pp.1259-1272
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• 2013

The purpose of this study was to investigate the effects of Science Writing Heuristic (SWH) laboratory class on the creative thinking and critical thinking of middle school students. Science writing heuristic programs were developed based on SWH strategies developed by Keys et al (1999). This study was conducted on 63 students from two classes as the comparative group and 63 students from two other classes as the experimental group. The cognitive level of the group as a homogeneous group was similar, and the program was applied to a total of 18 periods based on nine topics from March to July 2011. Evaluation instruments used in pre-test and post-test were the creative and critical thinking tests. To consider the score for creative and critical thinking. the SPSS 20.0 program was used. The study made use of technical statistics and ANCOVA. The result of this study showed that creative problem solving skills were improved by SWH in laboratory class. Therefore, persistent presentation of SWH teaching strategies and developing various experiment topics are required.