• Industrial Engineering and Management Systems
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• v.12 no.3
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• pp.264-273
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• 2013

Credit option is a policy that has been studied by many researchers in the area of supply chain management. This policy has been applied in practice to improve the profits of supply chain members. Usually, a credit option policy is proposed by the seller, and often under a symmetric information environment where members have complete information on each others' operations. In this paper, we investigate two scenarios: firstly, the seller offers a credit option to the buyer, and secondly, the buyer attempts to stretch the length of the credit period offered by the seller. The proposed model in both scenarios will be investigated under an asymmetric information structure where some information are private and are only known to the individual who has knowledge of this information. The interactions between buyer and seller will be modeled by non-cooperative Stackelberg games where the buyer and seller take turn as leader and follower. Among some of the numerical results obtained, the seller and buyer's profits obtained from symmetric information games are larger than those obtained from an asymmetric information game in both scenarios. Furthermore, both buyer and seller's profit in the second scenario are better than in the first scenario.

• Education of Primary School Mathematics
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• v.8 no.2 s.16
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• pp.69-96
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• 2004

The purpose of this study is to understand teaching and learning mathematics in elementary school classroom by considering mathematics as a kind of social practices and mathematics classroom as a kind of community of practice. The research questions of this study are as followings: 1) Which kinds of lesson organization reveal? 2) Which kinds of social participation structure reveal? 3) Which processes of making meaning reveal? This study was based on ethnomethodology. It was executed participation observations, interviews and surveys with teacher and 5 graders to collect the data related to the social practices formed their classroom. The social practices of mathematics classroom was analyzed from three aspects such as lesson organization, social participation structure and making meaning. The results from which we analyzed the social practices of the mathematics classroom are as followings. From the aspect of lessons organization, the teacher had a lot of power and authorities in the classroom and used them to elicitate students' responses. From the aspect of social participation structure, five SPSs(social participation structures) which revealed in Jo(1997)'s economics classrooms, were shown in this mathematics classroom, but there were a difference to the situations or frequencies which the SPSs appeared. From the aspect of making meaning, it was common that meanings are formed by the explanation of the teacher, but the teacher didn't deliver the mathematical meanings directly. She tried to interact with students to arrive shared meanings.

• School Mathematics
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• v.4 no.2
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• pp.261-282
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• 2002

This study intended to search for the way of NIE use as follows: 1) Setting up theoretical base about the way of NIE use to math loaming in primary school. 2) Analyzing the course mathematising through NIE use in math learning in practice. 3) Searching for the way of NIE use to aim at mathematising. As the result, this presented NIE model for mathematising according to the character of each step of the mathematising course. This paper says two things : The first, the way for using learning materials as reonstructing articles of newspapers to teach math learning 1) is searched for each information, scrapped to materialize. 2)is to extract the contents of NIE teaming available to the field and the unit of math curriculum. 3) searches for and applies the model for math NIE teaming. 4) makes up learning materials for each level using articles and presents the matters of deepening and supplement suitable for students. The second, the way for teaching math NIE with a view to helping students' mathematising during the course of teachers' math teaming. 1) reconstructs materials chosen by students' reality. 2) should offer students' communication and abundant context materials which mathematical model is possible. 3)needs to guide students to have motivation teaming so that they can mathematise their real matters by rediscovery 4) progresses mathematical activity using newspapers so that they can apply to new reality by applying informed Idea.

• School Mathematics
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• v.5 no.2
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• pp.209-221
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• 2003

This study focuses on the necessity of developing the material for teachers who are involved in diagnosing and prescribing students' mathematical errors. And it also intends to stimulate the related research of this area. For this, it tries to suggest the fundamental components-(1)types and frequencies of errors, (2) diagnostic test kit, (3)causes of errors, (4)ideas for prevention, (5)ideas for correction, (6)practice for settlement, and (7) performance test kit and frame of the teaching guide book for the teachers according to the general procedure of diagnosis and prescription. Finally it provides the concrete research areas for the future study.

• Journal of Educational Research in Mathematics
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• v.9 no.1
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• pp.151-165
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• 1999

In this study, I consider the meaning of activity as the source of mathematical knowledge. Mind-body dualism of Descartes which understands that knowledge precedes activity is somewhat overcomed by Ryle who understands that knowledge and activity are two sides of the same coin. But his discussion cannot offer the explanation about the foundation of rightness or the development of rules which can be expressed propriety of activity or rationality. Contrary to these views, Piaget solve this problem by the reasonability of 'the whole system of activity'. The theory of Dewey can be evaluated as an origin of activism of Piaget. Piaget considers knowledge as the system of activity itself, whereas Dewey considers knowledge as 'the result of activity'. This view of Dewey is related to the view of pragmatism which considers 'practice' is more important than 'theory'. The nature of 'activity' in this study has to be understanded as the interaction or the relation between the subject and the object. If we understand activity like this, we can explain that the whole structure of activity has the 'wholeness' that cannot be simply restored to the sum total of 'parts' and the new structure is a self-regulative transformation system which includes former structure continuously.

• Journal of Korean Society of Forest Science
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• v.96 no.4
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• pp.448-454
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• 2007

Mathematical models for predicting the ground and semi-ground skidding force have been developed. The skidding force is expressed as a function of log geometry, total weight and coefficient of skidding. The coefficient of skidding was determined under field tests. The validity of the model developed was examined by comparing the predicted and measured skidding forces. Calculated ground skidding force, using the model developed can be predicted well with that measured experimentally. The semi-ground skidding force calculated from the model, however, does not predict well due to its confined conditions experimentally.

• Honam Mathematical Journal
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• v.31 no.1
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• pp.109-124
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• 2009

Based on the observed data for Clarithromycin released, three commonly used inflow models: the power, the exponential, and the logarithmic models are considered. Among them, the power model is used most in practice for simplicity. Using the numerical parameter estimation techniques, the parameters appeared in the model equations are estimated. Through the numerical estimation results using the several experimental data sets, the exponential model turns out to be best among the three models. More specifically, the sum of squares of absolute errors and the sum of squares of relative errors for the exponential model are reduced by 80-95 % for the experimental data sets and 60-90 % for the noise added data sets compared with those for the power and logarithmic models. A typical experimental data set is used in this paper to show the estimation method and its numerical results. The proposed numerical method and its algorithm are designed for estimating the parameters appeared in the model differential equations for which the exact form of the solution is unknown in general. The methodology developed can be applied to more general cases such as the nonlinear ordinary differential equations or the partial differential equations.

• The Mathematical Education
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• v.40 no.2
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• pp.265-289
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• 2001

The elementary and middle school curriculum in Korea has been modified periodically to reach today's 7th national curriculum. Although the intent of each new curriculum was to improve education, lack of proper preparation for teachers and students has not made the new curriculums as effective as it could be. Goodlad et al.(1979) suggested that curriculum should encompass all practices including not only knowledge but all the elements of the curriculum and experiences of the student and teachers. The purpose of this paper is to investigate the actual practices of the current curriculum with focus on the use of instructional media in mathematics teaching and learning. A nationwide curriculum survey was carried out with the Goodlad's curriculum inquiry model as the framework. The result shows that elementary and secondary mathematics teachers used textbook manual (for teachers) and practice books most frequently for their class preparation. In addition to these, mathematics teachers also used manipulatives, visual aids, computers, internet, and calculators in a decreasing order. In general, many mathematics teachers did not use much instructional media in their classes and said that there are not enough effective instructional media to use. However, the teachers have positive attitude toward the educational media that they have used. In this study, we analyzed the survey data regarding educational tools, their use and effects to support the development of a new curriculum model in mathematics for a knowledge-based society.

• The Mathematical Education
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• v.53 no.1
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• pp.131-146
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• 2014

This study examines whether there is discrepancy between elementary and middle school mathematics teachers' beliefs and practices in constructed-response assessment and how their beliefs and practices are interrelated. Analyzing the responses of 212 elementary teachers and 189 middle school mathematics teachers to the questionnaire, we found that there is lack of consistency among elementary and middle school teachers' beliefs, practices, and expected benefits regarding constructed-response assessment. In addition, there was a weak correlation between each group of teachers' beliefs and expected benefits about constructed-response assessment. The results from this study imply that such inconsistency in elementary and middle school teachers' beliefs and practices regarding assessments may determine the effects of constructed-response assessment.

• The Mathematical Education
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• v.54 no.1
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• pp.1-11
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• 2015

The purpose of this study was to provide fundamental data and implication for forming desirable viewpoint of mathematics lesson critique and for improvement of expertise in lesson by compare and analyze the viewpoint of mathematics lesson critique of pre-service and in-service teachers. For the achievement of the purpose, The lesson critique materials of each 25 pre-service and in-service mathematics teachers were collected and arranged, and compare and analyze the viewpoint of mathematics lesson critique of pre-service and in-service teachers by using the standard for analyzing viewpoint of lesson critique composed of two categories, five main codes and 18 sub codes. The results of this study, both pre-service and in-service teachers have tendency for criticising lesson focusing on the practice rather than plan of lesson and both pre-service and in-service teachers showed evaluative reaction in most of critical statements and used positive ones rather than negative ones. The only pre-service teachers, though minor of them, showed non-evaluative reaction in criticising class and most of the statements were just description and explanation without any their own judgement for the scenes and activities of lessons and most of pre-service teachers have tendency to include reflection and introspection for their own class in lesson critique.