• Journal of the Korean School Mathematics Society
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• v.4 no.1
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• pp.115-124
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• 2001

This research is focused on the development of Math teaching and/or learning materials in which the students are centered, not teachers, and which can, in turn, activate and reinforce the students' extra curricular Math activitie The findings I came to have through my research can be summarized as follows: 1. Math teaching and/or learning materials developed based on the students' interactions in the Math extra-curricular activities helped students to learn Math better and to be more interested in Math. 2. There was a positive attitude change toward Math on the side of the students after being introduced in and exposed to Math through the above mentioned Math teaching and/or learning materials. 3. There was a positive attitude change toward Math on the side of the students after being taught Math using the above mentioned Math teaching and/or learning materials. The suggestions I came to have through my research are as follows: 1. There need to be more consistent efforts in developing the Math teaching and/or learning materials which can be used in the Math extra-curricular activities. 2. There need to be more consistent efforts in developing Math teaching paradigms which can be used in Math extra-curricular activities. 3. There need to be more consistent efforts in developing the Math teaching and/or learning materials which can be used in the Math class as well as in Math extra-curricular activities. 4. There need to be more consistent efforts in developing the Math teaching and/or learning materials which are more grade-, unit-, and category-conscious.

• The Mathematical Education
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• v.40 no.1
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• pp.53-66
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• 2001

The purpose of this work is to activate mathematics class in the extra curricular activity under the 7th curriculum. For that purpose, we investigate the current management of the extra curricular activity in the secondary school mathematics, and analysis the result. We suggest the main counterplan to activate mathematics class of extra curricular activity as following; (1) Develope teaching materials and programs for mathematics class. (2) Get the mathematics laboratory.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.255-258
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• 2003

In this study, to develop a flash-less die for forming of shoe-outsole, experiments and forming analysis were carried out. In order to reduce the extra-materials, of feet method and mass distribution method are used in the preform design. To improve the accuracy of contact surface of dies, the contact status of dies are measured by using the pressure film. The vertical pressing die structure and the guide-gutter system have been developed for the discharge of extra-materials and re-pressing. By the investigation, flash of shoe-outsole was considerably reduced.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.103-108
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• 2005

In this study, to develop a flash-less mold for forming of shoe-outsole, experiments and forming analysis were carried out. In order to reduce the extra-materials, offset method and mass distribution method are used in the preform design. The vertical mold structure pressing the preform was introduced to produce a flash-less shoe-sole. To measure the contact status of parting surface of mold, the pressure film has been used. The guide-gutter system and the continuous pressing mold have been developed for the discharge of extra-materials and re-pressing. By the investigation, flash of shoe-outsole was considerably reduced.

• Journal of Korean Elementary Science Education
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• v.21 no.1
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• pp.25-41
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• 2002

The Korean National curriculum is divided into the curriculum, discretion, and extra curriculum activity. Extra curriculum among them consists of fie grounds, that is, a self-governing, adjusting, developing, service and exercise activity. The content of developing activity among them includes academic literary arts, in that the developing activity related to science. The developing activity connected with science can be a good chance which students can have deepened learning besides a regular course. In addition, effective management in science class can play an important role to cultivate scientific sense and to raise scientific talent. The study finds out how the management connected with science-related extra-curricula activity in science is actually going on. The study carries out a questionnaire with 40 teachers and interviews 5 teachers as well who are in charge of science-related extra-curricula activity connected with science. As a result, on the side of students, ① systematic introduction course in science is not given to them, ② the course is operating without considering students interests and levels, so it causes the problems of developing their potential ability and extension. On the side of teachers, ① they organize the science department based on school's situation and policy. ② they disregard teachers' roles and interests. ③ the science department's program is operating improvisedly rather than systematically, ④ the evaluation is done formally is found out. I have come to know that to manage a desirable science-related extra-curricula activity connected with science needs to have sufficient, detailed materials and experts from outside.

• Transactions of Materials Processing
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• v.12 no.8
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• pp.730-737
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• 2003

Extensive studies have been conducted for reducing the residual stresses and birefringence in injection-molded optical disk substrate Flow-induced and thermally-induced stresses and birefringence have been found as two main sources during injection molding process. However, high speed rotation also induces extra stresses and birefringence in real operation of disk drives. In the present paper rotation-induced in-plane birefringence has been measured and presented for CD and DVD substrates at different radial position. About 10 - 15 nm of extra retardation in one pass has been measured up to 4,800 rpm. The distribution of extra rotation-induced birefringence will be valuable data for designing an optimal optical disk substrate. Finally, experimental results were compared with the extra stresses calculated from simple formulation.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.393-394
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• 2006

Highly compressible Ni-Mo steels are attractive materials for PM due to high sinter density and ease of processing. Extra-fine Ni admixed PM steels have demonstrated improved mechanical properties and rolling contact fatigue resistance due to a more uniform microstructure and increased Ni diffusion during sintering. Sinter densities of single press single sinter XF Ni-Mo steels can approach $7.5\;g/cm^3$ at moderate compaction pressures. Leaner alloys based on extra-fine Ni powder are possible depending on the performance requirements of the PM steel part. Extra-fine Ni steels are particularly attractive for the growing market of high performance PM gears and sprockets.

• Restorative Dentistry and Endodontics
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• v.37 no.3
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• pp.136-141
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• 2012

Objectives: The maintenance of the healthy periodontal ligament cells of the root surface of donor tooth and intimate surface contact between the donor tooth and the recipient bone are the key factors for successful tooth transplantation. In order to achieve these purposes, a duplicated donor tooth model can be utilized to reduce the extra-oral time using the computer-aided rapid prototyping (CARP) technique. Materials and Methods: Briefly, a three-dimensional digital imaging and communication in medicine (DICOM) image with the real dimensions of the donor tooth was obtained from a computed tomography (CT), and a life-sized resin tooth model was fabricated. Dimensional errors between real tooth, 3D CT image model and CARP model were calculated. And extra-oral time was recorded during the autotransplantation of the teeth. Results: The average extra-oral time was 7 min 25 sec with the range of immediate to 25 min in cases which extra-oral root canal treatments were not performed while it was 9 min 15 sec when extra-oral root canal treatments were performed. The average radiographic distance between the root surface and the alveolar bone was 1.17 mm and 1.35 mm at mesial cervix and apex; they were 0.98 mm and 1.26 mm at the distal cervix and apex. When the dimensional errors between real tooth, 3D CT image model and CARP model were measured in cadavers, the average of absolute error was 0.291 mm between real teeth and CARP model. Conclusions: These data indicate that CARP may be of value in minimizing the extra-oral time and the gap between the donor tooth and the recipient alveolar bone in tooth transplantation.

• Korean Journal of Materials Research
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• v.14 no.12
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• pp.863-869
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• 2004

The purpose of this research is to investigate the mechanical property and ductile-brittle transition temperature of Ti-Nb-P added extra low carbon interstitial free steel having a tensile strength of 440 MPa. The mechanical property and transition temperature of hot rolled steel sheets were more influenced by the coiling temperature rather than by the small amount of alloying element. Further, at the same composition, the property of the specimen coiled at low temperature was superior to that obtained at higher coiling temperature. The fracture surface of 0.005C-0.2Si-1.43Mn steel coiled at $630^{\circ}C$ showed a ductile fracture mode at $-100^{\circ}C$, but coiling at $670^{\circ}C$ showed a transgranular brittle fracture mode at $-90^{\circ}C$. The galvannealed 0.006C-0.07Si-1.33Mn steel sheet annealed at $810^{\circ}C$ has tensile strength and elongation of 442.8 MPa and $36.6\%$, respectively. The transition temperature of galvannealed 0.006C-0.07Si-1.33Mn steel sheet was increased with a drawing ratio, and the transition temperature of the galvannealed 0.006C-0.07Si-1.33Mn steel was $-60^{\circ}C$ at a drawing ratio of 1.8

• Journal of Korean Foot and Ankle Society
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• v.6 no.1
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• pp.7-14
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• 2002

Purpose: We investigate the characteristic morphologic features and suggest proper treatment of postaxial polydactyly of the foot Materials and Methods: We analysed 37 cases of postaxial polydactyly. Mean post operative follow up period was 2 years 10 months. We analysed them according to morphological, radiological and operative findings. Patients were classified into extra 5th toe polydactyly and extra 6th toe polydactyly based on the abnormal extradigit, and subdivided into joint origin type, bone origin type and floating type based on duplication pattern. Results: 23 cases were extra 5th toe polydactyly and 14 cases were extra 6th toe polydactyly. Most common types were metatarsophalangeal joint origin type of extra 6th toe polydactyly. Compared with extra 5th toe polydactyly, extra 6th toe polydactyly originated from more proximal part and had not syndactylism. Conclusion: As the duplication level was more distal, degree of syndactylism and nail union was more severe. In case of syndactyly between 5th and 6th toe, abnormal extradigit was 5th toe.