• Proceedings of the Korean Nuclear Society Conference
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• 1999.10a
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• pp.67.1-67
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• 1999

• Journal of Biomedical Engineering Research
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• v.28 no.6
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• pp.803-810
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• 2007

Although synthetic aperture focusing techniques can improve the spatial resolution of ultrasound imaging, they have not been employed in a commercial product because they require a real-time N-channel beamformer with a tremendously increased hardware complexity for simultaneous beamforming along M multiple lines. In this paper, a hardware-efficient beamformer architecture for synthetic aperture focusing is presented. In contrast to the straightforward design using NM delay calculators, the proposed method utilizes only M delay calculators by sharing the same values among the focusing delays which should be calculated at the same time between the N channels for all imaging points along the M scan lines. In general, synthetic aperture beamforming requires M 2-port memories. In the proposed beamformer, the input data for each channel is first upsampled with a 4-fold interpolator and each polyphase component of the interpolator output is stored into a 2-port memory separately, requiring 4M 2-port memories for each channel. By properly limiting the area formed with the synthetic aperture focusing, the input memory buffer can be implemented with only 4 2-port memories and one short multi-port memory.

• Journal of Educational Research in Mathematics
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• v.15 no.2
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• pp.215-232
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• 2005

Computer algebra system (CAS) calculators are becoming increasingly common in schools and universities. While Hey offer quite sophisticated mathematical capability to teachers and students, it is not clear at present how they may best be employed. In particular their integration into students' learning and problem-solving remains an issue. In this paper we address this issue through the lens of a study that considered the introduction of the TI-89 CAS calculator to students about to enter university. We describe a number of different aspects of the partnership they formed with the calculator as they began the process of instrumentation of the CAS in their learning.

• Research in Mathematical Education
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• v.4 no.2
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• pp.79-93
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• 2000

The purpose of this article is to introduce the gifted education of mathematics in Korea. We first discuss what is going on in Korea for mathematics education for gifted students. The curriculums for the institutes for gifted education are mentioned. Some focus of this article is proposing some teaching materials that are actively utilizing many basic concents of cryptography and super-string theory, along with careful use of calculators and computers. Many of the materials haven been designed with problem-posing approach on through invoking the cognitive conflict.

• Research in Mathematical Education
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• v.1 no.1
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• pp.43-59
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• 1997

Now in Korea, the 7th curriculum reform is underway. The main difference of the seventh curriculum compared with former curricula is that it puts much emphasis on individual difference. It is a "differentiated" curriculum. The basic directions of the 7th mathematics curriculum are as follows: 1. Offer various mathematical subjects for "Selective Educational Period" (Grades 11 and 12). 2. 30% reduction of mathematical contents. 3. The reconciliation of domain names of school mathematics. 4. The use of computers and calculators in mathematics classrooms.

• The Mathematical Education
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• v.43 no.1
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• pp.1-12
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• 2004

We have studied the issues of the current math war in America. Traditionalists and the reformers have been arguing about the curriculums, teaching methods, use of calculators, basic skills, and assessment methods in K-12 mathematics. They both have strengths and weaknesses depending on the situation have contributed for the development of mathematics education. Instead of choosing between traditionalists and the reformist sides, we suggest to adopt an eclectic view point i.e., rigor and creativity, memorization and understanding that may seem at odds with each other are quite compatible and mutually reinforcing. Also teacher's deep knowledge in mathematics is extremely important as his/her knowledge in pedagogy.

• School Mathematics
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• v.10 no.2
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• pp.297-317
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• 2008

This study was designed to gain insight to adopt CAS into secondary level algebra education in Korea. Most inactive usage of calculators in math and most negative effects of calculators on their achievements of Korean students were shown in International studies such as TIMSS-R. A comparative study was carried out with consideration of mathematical backgrounds and technological environments. 8 Korean students and 26 US students in Grade 11 were participated in this study. Subjects' Problem solving process and their strategies of CAS usage in classical Box-problem with CAS were analyzed. CAS helped modeling by providing symbolic manipulation commands and graphs with students' mathematical knowledge. Results indicates that CAS requires shifts focus in algebraic contents: recognition of decimal & algebraic presentations of numbers; linking various presentations, etc. The extent of instrumentation effects on the selection of problem solving strategies among Korea and US students. Instrumentation

• Communications of Mathematical Education
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• v.24 no.3
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• pp.611-626
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• 2010

The purpose of this study is to explore the composite properties of linear functions using CAS calculators. The meaning and processes in which technological tools such as CAS calculators generated to instrument are reviewed. Other theoretical topic is the design of an exploring model of observing-conjecturing-reasoning and proving using CAS on experimental mathematics. Based on these background, the researchers analyzed the properties of the family of composite functions of linear functions. From analysis, instrumental capacity of CAS such as graphing, table generation and symbolic manipulation is a meaningful tool for this exploration. The result of this study identified that CAS as a mediator of mathematical activity takes part of major role of changing new ways of teaching and learning school mathematics.

• The Journal of Korean Association of Computer Education
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• v.5 no.3
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• pp.79-87
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• 2002

Theorema system is built on top of Mathematica to automate deductive reasoning processes as the combination of computer algebra system and deductive system. Theorema system that was developed at RISC in Austria provides three modes based on rewriting techniques; computation, problem solving and proving. This paper shows how the computation mode of Theorema can simulate Derive part for TI-92 graphic calculators to produce TI-92 manuals. Moreover, it also describes how such manuals can be converted to web-based learning materials via Java servlet.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.2
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• pp.27-34
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• 2010

The PERT is one form of probabilistic network and can have many critical paths in the concept of each work has dispersed complete time. Here we propose two operators to estimate the probabilistic complete time about serial and parallel connections, and in each junction node, probability of critical path is estimated by new operator. Then we compare the estimated results with robability of critical path with deterministic CPM and Monte Carlo simulation (MCS). Our results show that all paths in PERT can be critical path, and proposed operators are efficient and accurate probabilistic calculators compare MCS result.