• The Mathematical Education
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• v.40 no.2
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• pp.335-343
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• 2001

Algebra is important part of mathematics education. Recent days, many mathematics educators emphasize on real world situation. Form real situation, pupils make sense of concepts, and mathematize it by reflective thinking. After that they formalize the concepts in abstract. For example, operation in numbers develops these course. Operation in natural number is an arithmetic, but operation on real number is algebra. Transition from arithmetic to algebra has the cutting point in representing the concepts to mathematics sign system. In this note, we see the cognitive tendency of 10th grade about operation of real number, their cutting point of transition from arithmetic to algebra, and show some methods of helping pupils.

• Management & Information Systems Review
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• v.17
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• pp.107-133
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• 2005

The purpose of this study was to analyze a trend of profitability classified by characteristics of hospitals and to analyze related factors. The data for this study were derived from survey material conducted by the Korean Hospital Association on 33 hospitals in Korea between 1993 and 2002. Profitability was measured in the aspect of investment profit rate and operation profit rate with net profit to total assets, normal profit to total assets and operating margin to gross revenue as dependent variables. Independent variables were classified by general factors (ownership, number of beds, period of establishment, region), financial factors (total asset turnover, liabilities to total assets, current ratio, fixed ratio, inventories turnover, personnel costs per operation profit, material costs per operation profits), composition of manpower and facilities(personnel and area per beds), productivity index(the number of daily patients per medical doctor, the number of daily patients per nurse), the score of quality assurance activities. First, Concerning the specialists per beds or area per beds and profitability of hospitals there was not statistically significant. Second, Those hospitals having the most daily patients per nurse had significantly higher profitability than the others, but the number of daily patients per medical doctor had little effect on the profitability. Thirds, Those hospitals having a higher proportion total asset turnover tended to show significantly higher profitability compared to other hospitals, but the liabilities to total assets and liquidity ratio had a little difference to the profitability. Those hospitals having a higher proportion personnel costs per operation profit and material costs per operation profits tended to show significantly lower hospital profitability compared to other hospitals. Fourth, In regression analysis, hospital profitability had negative relationship with personnel costs per operation profit or material costs per operation profits. While it had positive relationship with total asset turnover, the number of daily patients per nurse. In conclusion, private hospitals had higher profitability than that of public hospitals. Though factors related to profitability of hospital were different according to ownership, it is important for securing appropriate profitability by operating appropriate number of nurse, raising total asset turnover, and reducing personnel costs, material costs per operation profits. This study can be used as a baseline data for planning of hospital management. But the study may be limited in that the results cannot be generalized due to its small sample size. However, this longitudinal observation of 33 hospitals over ten year period has significant merit alone.

• Journal of Educational Research in Mathematics
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• v.19 no.4
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• pp.513-530
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• 2009

In this paper, We analyse the contents of the national mathematical curriculum, the handbook of the curriculum, and elementary school mathematics textbook for the elementary school grade 1-2 focusing on 'number sense'. At first, we identify the meaning and the elements of number sense through analysing studies which are related to number sense. Number sense includes understanding the meaning of number, operation, and estimation, and the ability of applying numbers, operation and estimation on the context. Number sense consists of the elements of the contents and the elements of the processes. Secondly, with the elements of number sense which we have identified, we analyse the contents of the national mathematical curriculum, the handbook of the curriculum, and elementary school mathematics textbooks, and then criticize the contents. We find some problems as a result of the analysis : the range of number sense is unclear, the word 'number sense' is not used consistently, the elements used are limited, and the contents of the textbook are materialized inconsistently and poorly.

• Korean Journal of Child Studies
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• v.30 no.1
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• pp.109-125
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• 2009

This study examined the effects of estimation activities on children's operation and measurement abilities. Subjects were 60 five-year-old children. This experiment used the untreated control group design with pretest and posttest. Instruments used to collect data were the Number and Operation and Measurement tests part of the Test of Mathematics Ability for Young Children (TMAYC) developed by Hong, Lee and Chung (2006). ANCOVA was employed for statistical analysis. Results of the posttest showed that children in the experimental group scored significantly higher on children's operation and measurement abilities than the control group. Results imply that an estimation program can be an effective teaching model for improving children's operation and measurement abilities.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.249-263
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• 1997

This paper addresses the parts route selection and economic design in flexible manufactuirng system (FMS). Parts are processed through several stage workstations according to operation sequences. The machine of each workstation can do multiple operation functions. And the operation stage of a part can be processed in several workstations, which are non-identical in functional performance. The objective of this paper is to determine the processing routes of parts, number of machine at each workstation, number of vehicle and makespan time. Two models are suggested. One is assumed that the operation stage of parts can be processed at the only one among several available workstations. Other is assumed that the operation stage of parts is allowed to be processed at several workstations. Parts are transported by automated guided vehicles (AGVs). The decision criteria is to minimize the sum of processing cost, travel cost, setup cost and overhead cost. The formulation of models is represented. A solution algorithm is suggested, and a numerical example is shown.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.1047-1053
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• 2005

This study explored pattern of train operation between Seoul Cheonan after the introduction of KTX in 2004. Both number of trains and seat capacity per day have increased but maximum number of trains per specific hour hasn't changed much. Demand for train shows that it concentrated in a specific time, so number of trains during the peak hour should be increased. But, it is difficult due to line capacity, so increasing seat capacity per train might be an option. An increase in seat capacity should be considered the characteristics of each train lines.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.3
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• pp.312-319
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• 2004

The optimum dosage control is presumably the goal of every water treatment plant. However it is difficult to determine the dosage rate of coagulant, due to nonlinearity, multivariables and slow response characteristics, etc. To deal with this difficulty, the real number genetic-fuzzy system was used in determining the dosage rate of the coagulant. The genetic algorithms are excellently robust in complex optimization problems. Since it uses randomized operators and searches for the best chromosome without auxiliary informations from a population which consists of codings of parameter set. To apply this algorithms, we made the real number rule table and membership function from the actual operation data of the water treatment plant. We determined optimum dosages of coagulant(LAS) using the fuzzy operation and compared them with the dosage rate of the actual operation data.

• Journal of Veterinary Clinics
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• v.15 no.1
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• pp.124-130
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• 1998

This study was performed to evaluate the new surgical technique for debarking. Of the 8 mongrel dogs which underwent devocalization, 4 heads (group 1) received complete surgical removal of the vocal cords and another 4 heads (group 2) received fixation of vocal cords and vocal processes onto the thyroid cartilage. Volume of each dogs' voices was measured by a sound level meter(Function A) over 7 months at intervals of 10 days. All experimental animals'hematological values were measured before operation and postoperative at 2i 5 and 10 days. The changes of volume of dogs'voices and hematological values were analyzed by paired t-test. The volume in the dogs'voices in each group after operation was significantly lower than that before operation. At this results we detected that devocalizing effect was the same in each group. Postoperative volume of dogs'voices in group 1 had a tendency to increaser but group 2 had a tendency to decrease. The number of erythrocytes at 2 days after operation was significantly fewer than those before operation in group 1, but the group 2 did not have significant changes. The number of leukocytes at 2 days after operation significantly increased from those before operation in group 11 but the group 2 did not have significant changes. It was concluded that the new surgical technique, fixation of vocal cords and vocal processes onto the thyroid cartilages could be available for the devocalization of dogs and for the prevention of postoperative inflammation and blood loss.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.2
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• pp.37-44
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• 2012

This paper focuses on scheduling problems arising in the military. In planned artillery attack operations, a large number of threatening enemy targets should be destroyed to minimize fatal loss to the friendly forces. We consider a situation in which the number of available weapons is smaller than the number of targets. Therefore it is required to develop a new sequencing algorithm for the unplanned artillery attack operation. The objective is to minimize the total loss to the friendly forces from the targets, which is expressed as a function of the fire power potential, after artillery attack operations are finished. We develop an algorithm considering the fire power potential and the time required to destroy the targets. The algorithms suggested in this paper can be used in real artillery attack operations if they are modified slightly to cope with the practical situations.

• Journal of the Korean School Mathematics Society
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• v.8 no.4
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• pp.423-444
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• 2005

Despite the importance of number sense, computational skills have been emphasized in elementary mathematics curriculum. There is lack of research on number sense. Against this background, this study analyzed the way 137 sixth grade students coped with routine computation problems and with problems requiring number sense. Students performed better on the computation tasks than on the number sense tasks. With regard to the number sense tasks, many students had a tendency to implement direct computation rather than to use number sense appropriate to the given contexts. Students also had difficulties in making use of effective benchmarks or applying the knowledge of number and operation to various problem contexts. An implication is that students should explore multiple tasks requiring number sense as an integral part of their mathematics learning in order to develop number sense.