• Journal of Korean Elementary Science Education
• /
• v.26 no.2
• /
• pp.141-148
• /
• 2007

This study proposed task-based teaming strategies as a means of fulfilling the demands and goals of the 7th national science curriculum. Task-based learning is based on the use of a series of activities whereby a teacher presents students with tasks related to daily lift and the students solve the tasks by themselves using various methods and thought processes and then present and discuss their results with each other. The tasks are selected from the 6-grade science textbook, are reconstructed and are then given to the classes. The tasks include whole class activities as well as individual activities related to the interests, abilities, and concerns of the students. The purpose of this study was to verify the effects of task-based learning classes on the science process skills and the scientific attitudes of elementary school students, when applied to 6th grade students. For this, the task-based learning activities were applied to an experimental group and expository teaching was applied to the comparison group. Both groups were given a pre-post test on science process skills and scientific attitudes. The results indicate that task-based loaming is very effective in the development of science process skills and scientific attitudes.

• Journal of Educational Research in Mathematics
• /
• v.18 no.3
• /
• pp.335-352
• /
• 2008

The purpose of this research was to investigate the descriptive evaluation method that focuses on the problem solving process of the student. The goal was to evaluate the students' understanding of the subject rather than the students' ability to find the final answer. The descriptive evaluation is being suggested as a way of examining the thought process of the student by performing a structured analysis of the problem solving process. Today, there are not enough descriptive evaluation resources available for teachers to effectively carry out this alternative assessment method in the elementary school mathematics curriculum. This research is a case study on the development of resources for descriptive evaluation in grade 4 mathematics. We designed the development process for descriptive evaluation and its rubric for all 8 units of the 4-Na level of mathematics in the elementary school curriculum. Three descriptive problems were developed for each of the 8 units for a total of 24 problems. The rubric consisted of three areas of assessment, 1) understanding of the problem, 2) problem solving, and 3) mathematical communication. The problems were first pilot tested in two 4th grade classes. Modified problems were then tested in a different 4th grade classroom. The study showed that the three defined areas of evaluation framework (problem understanding, problem solving and mathematical communication) were measurable and analyzable using the developed grading rubric. We then conclude that he descriptive evaluation could be used as an effective tool for improving teacher performance in elementary school mathematics.

• Korean Chemical Engineering Research
• /
• v.57 no.5
• /
• pp.743-748
• /
• 2019

This study focuses on the simulation of wet flue gas desulfurization process for improving the production of gypsum by the utilization of low-grade limestone. At present, high-grade limestone with a $CaCO_3$ content of 94% is used for producing merchantable gypsum. In modeling process, a lot of reactions are considered to develop model. First, the limestone dissolution is simulated by RSTOIC model. Second, SOx absorption and crystallization is used by RCSTR model. Finally the gypsum is separated by using SEPERATORS model. Modeling steps make it easy to reflect further side reactions and physical disturbances. In optimization condition, constraints are set to 93% purity of gypsum, 94% desulfurization efficiency, and total use of limestone at 3710 kg/hr. Under these constraints, the mass flow of low-grade limestone was maximized. As a result, the maximum blending quantity of low-grade limestone for 2,100 kg of high-grade limestone that satisfies constraints is about 1,610 kg.

• Resources Recycling
• /
• v.32 no.2
• /
• pp.3-11
• /
• 2023

The aim of this study was to develop a physical treatment method for obtaining iron concentrate with a grade higher than 60% from slag generated in the Waelz Kiln (WK) process. The size of the WK slag used in this work was several millimeters, with T-Fe and ZnO contents of 40.24% and 1.03%, respectively. The slag samples were pulverized in a laboratory rod mill for various grinding times, followed by a magnetic separation test under a low magnetic intensity of 0.05 T initially. The results showed that the highest iron grade was obtained from samples with a grinding time of 10 min. Additionally, for a grinding time of 20 min, the highest grade and recovery ratios were achieved at a magnetic intensity of 0.8 T. Based on these findings, the optimal physical treatment process proposed in this study resulted in iron concentrates with a grade of 61.34% and an enrichment ratio of 1.52.

• Journal of the Korean Chemical Society
• /
• v.48 no.4
• /
• pp.414-426
• /
• 2004

This study analysed inquiry process and activities of the inquiry area in the chemistry field of middle school science textbooks by the inquiry elements based on the 7th science curriculum. The purpose of this study is to grasp a degree of reflecting the 7th science curriculum in the 9th grade science textbooks, and to find out educational implications for the various inquiry learning. Overall, for the analysis of inquiry elements, basic inquiry elements except classification were well reflected on the middle school science textbooks in 9th grade. However, for the integrated inquiry elements, interpreting data occupies almost half of them. This phenomenon is shown in the analysis of inquiry process and inquiry activities, as well. Especially, project and field trip introduced in the 7th science curriculum are hardly found in the textbooks. 9th grade is classified as an upper grade in the 7th science curriculum in terms of inquiry level. Integrated inquiry elements and inquiry activity types, however, are not thoroughly reflected in the 9th grade science textbooks. It is desirable that a variety of inquiry learning of 9th grade be implemented by reconstructing inquiry area based on the results of this study. Hence the degree and ratio of utilizing the integrated inquiry elements and inquiry activity types to the inquiry area of science textbook in 9th grade should be studied.

• Journal of Korean Elementary Science Education
• /
• v.20 no.1
• /
• pp.45-57
• /
• 2001

The purpose of this study is to guide and apply gettable and accessible materials around everyday life into classroom instruction, and to find out their effects on student academic achievement. In order to achieve it, this study was tried to develop and guide available materials around life in teaming activities, to provide a preliminary assignment that could apply the available materials, and to compare its academic achievement to one from field trip loaming. For the hypothesis testing, first, the experimental and comparing classes were selected based on the results of basic learning diagnostic evaluation, which conducted by the researcher being served as a full-time science teacher of the third and sixth grade of K elementary school in Kwangju for 2 years. Secondly, the instructional use of the available materials around life was applied to the experimental class. Also, the instructional use of the existing materials was applied to the comparing class. Finally, for the testing of the effects on academic achievement, the posterio test was implemented after conducting the experimental instruction in knowledge·understanding, inquiry process, and attitude domains classified by the unit characteristics. Using SPSS/WIN program the t-test was performed in order to compare the differences between the two groups. Major findings were as follows: 1) In the achievement test of knowledge·understanding domain, there were no significant differences at the 5％ level between the experimental and comparing classes. It could be difficult to say, therefore, that the instructional use of the available materials around life was more effective than the instructional use of the existing materials. However, it had some effects on differences between the third grade final achievement test and sixth grade experimental class. 2) In the achievement test of inquiry process domain, there were some significant differences in that the sixth grade experimental class was higher than the third grade out-of classroom experience unit. It was indicated that the instructional use of the available materials around life had some effects on improving the students' inquiry ability 3) In achievement test of attitude domain, there were some significant differences. It was shown that the self-evaluation test of the sixth grade experimental class unit was higher than that of the third grade out-of classroom experience unit; Especially, the learning activities in the experimental class were more active, and the experimental practice ability was improved. It was presented that the instructional use of the available materials around life had some effects on the students' academic achievement in attitude domain. It was concluded from this study that the instructional use of the available materials around life was less effective on Knowledge understanding domain, but was effective on improving their scientific inquiry ability and interest on science education.

• Journal of Welding and Joining
• /
• v.29 no.1
• /
• pp.65-73
• /
• 2011

Microstructural characteristics of two high strength (600 MPa & 800 MPa) weld metals produced by flux-cored arc welding process (FCAW) were evaluated. The 600 MPa grade weld metal was consisted of 75% acicular ferrite and 25% ferrite which was formed at relatively high temperature (grain boundary ferrite, widmanstatten ferrite, polygonal ferrite). However, the 800 MPa grade weld metal was composed of about 85% acicular ferrite and 15% low temperature forming phases (bainite, martensite). The prior austenite grain size of 800 MPa grade weld metal was decreased by solute drag force. The compositions and sizes of inclusions which are the dominant factors for the formation of acicular ferrite were analyzed by a transmission electron microscopy (TEM). In both 600 MPa and 800MPa grade weld metals, the inclusions were mainly consisted of Ti-oxide and Mn-oxide, and the average size of inclusions was $0.7{\mu}m$. The 800 MPa grade weld metal exhibited higher tensile strength and similar toughness compared with the 600 MPa grade weld metal. This result is mainly due to a higher fraction of low temperature products and a lower fraction of grain boundary ferrite in the 800 MPa grade weld metal.

• BMB Reports
• /
• v.46 no.5
• /
• pp.244-251
• /
• 2013

Lignocellulosic materials are commonly used in bio-$H_2$ production for the sustainable energy resource development as they are abundant, cheap, renewable and highly biodegradable. In the process of the bio-$H_2$ production, the pretreated lignocellulosic materials are firstly converted to monosaccharides by enzymolysis and then to $H_2$ by fermentation. Since the structures of lignocellulosic materials are rather complex, the hydrolysates vary with the used materials. Even using the same lignocellulosic materials, the hydrolysates also change with different pretreatment methods. It has been shown that the appropriate hydrolysate compositions can dramatically improve the biological activities and bio-$H_2$ production performances. Over the past decades, hydrolysis with respect to different lignocellulosic materials and pretreatments has been widely investigated. Besides, effects of the hydrolysates on the biohydrogen yields have also been examined. In this review, recent studies on hydrolysis as well as their effects on the biohydrogen production performance are summarized.

• Journal of Nutrition and Health
• /
• v.21 no.5
• /
• pp.333-347
• /
• 1988

The purpose of the present study was to investigate the relationship between nutrient status, and bone mineral state which influenced by aging process. The subjects were 196 people over 65 years old(male 72, female124). The present dietary intake was estimated by the 24-hr, recall method, and individual dietary history concerning consumption of meat, fish and dairy products was obtained by questionaires. The syndrome of senility including seniliy was evaluated according to "Cornell Medical Index". The five subjects who showed 'Good' grade in bone senility, and five subjects who showed 'Risk' and 'Danger' grade were selected and their spine and femur bone density was measured by "Dual Photon Absorptiometry". The bone density measurement showed that the subjects with 'Good' grade in bone senility had bone density above that of normal person, and their nutrient status were satisfactory, whereas the subjects with 'Risk' and 'Danger' grade in bone senility had severe osteoporotic pattern, and their nutrient status were very poor. The food consumption score showed that the subject with higher intake of meat rather than milk had good grade in bone senility (p<0.05). Therefore, past meats consumption can be considered to be a significant factor in the present bone status. The nutrient intakes appeared to be significant factors in bone status in male, whereas there was little effect of nutrients intakes in female. Therefore, the risk of osteoporosis can increase as syndrome of bone senility and nutrient intakes were worse, and its is possible to evaluate bone status and predict osteoporosis simply from informations concerning syndrome of bone senility and nutrient intakes in old population over 65.

• Journal of the Korean Ceramic Society
• /
• v.47 no.6
• /
• pp.618-622
• /
• 2010

Cost-effective purification methods of silicon were carried out in order to replace the conventional Siemens method for solar grade silicon. Firstly, acid leaching which is a hydrometallurgical process was preceded with grinded silicon powders of metallurgical grade (~99% purity) to remove metallic impurities. Then, plasma treatments were performed with the leached silicon powders of 99.94% purity by argon plasma at 30 kW power under atmospheric pressure. Plasma treatment was specifically efficient for removing Zr, Y, and P but not for Al and B. Another purification step by EB treatment was also studied for the 99.92% silicon lump which resulted in the fast removal of boron and aluminum. That means the two methods are effective alternative tools for removing the doping elements like boron and phosphor.