• Journal of Biomedical Engineering Research
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• v.16 no.3
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• pp.301-308
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• 1995

A high-precision pre-amplifier is designed for general use in EEG measurement system. It consists of signal generator, signal amplifier with a impedance converter, shield driver, body driver, differential amplifier, and isolation amplifier. The combination of minimum use of inaccurate passive components and the appropriate matching of each monolithic amplifiers results in good noise behavior, low leakage current, high CMRR, high input impedance, and high IMRR. The performance of EEG pre-amplifier has been verified by showing the typical EEG pattevn of a nomad person through the clinical experiments.

• Progress in Superconductivity
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• v.5 no.2
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• pp.124-127
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• 2004

Many of research efforts have been focused on the improvement of critical current density (Jc) of silver-sheathed Bi-2223 tapes far practical applications. In this study, the transformation of Bi-2212 phase was investigated, which was transformed to orthorhombic from tetragonal through pre-annealing during powder packing and drawing process. The relationship between hardness of Bi-2212 orthorhombic phase and workability of Bi-2223/Ag tape was investigated. Bi-2223 superconducting wires with 55 filaments were fabricated by stacking and drawing process with different heat-treatment histories. Before rolling process, round wires were pre-annealing at 76$0^{\circ}C$ and in a low oxygen partial pressure. We confirmed that pre-annealing step was to transform to Bi-2212 orthorhombic structure from Bi-2212 tetragonal structure and to reduce the formation of second phases. However the breakages were created at Ag-alloy clad during rolling for pre-annealed Bi-22231Ag tapes. Several pre-annealing scenarios were introduced to reduce the breakages during rolling process. Microstructure and critical current density of pre-annealed Bi-2223 superconducting tapes were investigated. We could achieve proper pre-annealing conditions for Ag-alloy clad Bi-2223 superconducting tapes.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.10 no.1
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• pp.1-10
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• 2007

Outcome of liver transplantation for children with end liver disease has been improved markedly during last two decades. Improvement of immunosuppressive agent and its strategy to use in children, development of innovative surgical technique, and better understanding of the course of liver transplantation attributed to better outcome of pediatric liver transplantation. Therefore this review article will focus on the problems which can occur during pre- and post-transplantation period, current strategy to use immunosuppressive agent for the better understanding of pediatrician who is not involved in transplantation but takes care of the children pre- and postoperatively.

• Korean Journal of Computational Design and Engineering
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• v.18 no.6
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• pp.407-416
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• 2013

Acting an important risk management tool for main contractors, pre-qualification has served a key marketing tool for subcontractors in various industries. Current industrial environment has required the time intensive pre-qualification ability to small and medium-size subcontractors as a matter of competitive business. In order to support the subcontractors, this paper proposes a database model for pre-qualification management system (PQMS) that automates the pre-qualification process by using information technologies. The modeling process consists of specifications for its requirements, functional modules, and a database model for the PQMS.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.205-208
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• 2009

The purpose of this study is to apply the process model of the pre-design stage to CPLM(Construction Project Life-cycle Management). Life-cycle consists of 4 stage; Pre-design, Design, Construction, Maintenance. Each stage has organic relations between front and rear stage. Therefore it is important to manage and use the information data of each stage. But these data are not carried to the next stage smoothly, especially at the pre-design stage. It is even vague to define the process of the pre-design stage. To carry and share the information well, this study defines Pre-design stage process and CPLM at first, VA-Cityplanner which is the development system of the pre-design process model is applied to CPLM for the smooth current of the data between participants.

• Journal of Electrical Engineering and Technology
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• v.7 no.5
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• pp.778-783
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• 2012

The synthetic short-circuit making test to adequately stress the circuit breaker has been specified as the mandatory test duty in the IEC 62271-100. The purpose of this test is to give the maximum pre-arcing energy during making operation. And this requires the making operation with symmetrical short-circuit current that is established when the breakdown between contact gap occurs near the crest of the applied voltage. Also, if the interrupting chamber of circuit breakers is designed as the type of common enclosure or the operation is made by the gang operated mechanism that three-phase contacts are operated by one common mechanism, three-phase synthetic making test is basically required. Therefore, several testing laboratories have developed and proposed their own test circuits to properly evaluate the breaker performance. With these technical backgrounds, we have developed the new alternative three-phase making circuit.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.152-155
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• 2009

In high power application, PFC(Power Factor Correction) pre-regulators are generally required. PFC pre-regulators could achieve unity power factor, reduce line input current harmonics and utilize full line power. Interleaving PFC converters could reduce input ripple current, output capacitor ripple current and inductor size. With this closed loop interleaving method, both two phase converters are working at the boundary between continuous and discontinuous mode and accurate 180 degree phase shift is achieved. Implementation of this strategy could be easily integrated to the control chip. Finally, experimental results of a two-phase interleaved boost PFC are presented to verify the discussed features.

• Journal of Korean Elementary Science Education
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• v.36 no.1
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• pp.85-94
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• 2017

The purpose of this study was to investigate the perspectives of pre-service elementary teachers on science education of future by using Draw-A-Science-Teacher-Test Checklist and open-ended questionnaire. The subjects of this study were 136 pre-service elementary teachers. The results of the research are as follows. The pre-service teachers thought that the physical environment reflecting the latest science and technology for science education will be developed in the future. However, few respondents indicated that student-centered equipment or a free and creative classroom environment would be provided. Second, they predicted that there would be changes in teacher's activities due to the introduction of advanced facilities and equipment, but most of the other teachers' activities were thought to be similar to those of current teachers. Third, the pre-service elementary teachers thought that a variety of new technologies would be used in science education and science teachers would mainly teach high-technology, IT technology, science knowledge, and newly discovered science concepts. In addition, we found that pre-service elementary teachers' images were more 'teacher-centered' than 'student-centered'. These results show that pre-service elementary teachers are expected to utilize the latest science and technology actively in science education in 2030 and that it will lead to changes in the physical environment, teachers' activities, education contents, and teaching and learning methods. In addition, they viewed acquisition of science concept as an important goal of science education in the future and had different points of view from the current science education curriculum and scholars' emphasis on educational research for the future.

• Journal of The Korean Society of Integrative Medicine
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• v.6 no.2
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• pp.117-123
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• 2018

Purpose : The purpose of this study was to investigate the effect of increased brain activity on the muscle endurance and the effect of brain activation through the combination of transcranial direct current stimulation and aerobic exercise on elderly woman. Methods : To investigate the effect of the muscle endurance on right leg, muscle endurance was evaluated by measuring the surface EMG of the muscles of the rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius muscle. Results : There was a significant difference in the pre and post comparisons of muscle endurance on rectus femoris, biceps femoris, tibialis anterior muscle (p<.05). Difference of Combination of transcranial direct current stimulation and aerobic exercise group median frequency was smaller than control group (p<.05). There was not a significant difference in the pre and post comparisons of muscle endurance on biceps femoris, and gastrocnemius muscle. Difference of Combination of transcranial direct current stimulation and aerobic exercise group median frequency was showed a similar pattern. Conclusion : Through these results, It was found that increasing the brain activity by the transcranial direct current stimulation improves the exercise capacity on the elderly women. Combination of transcranial direct current stimulation and aerobic exercise maybe applied as an effective treatment for improving muscular endurance.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.81-85
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• 2015

The organic/inorganic hybrid photovoltaic devices have been studied using Poly(3-hexylthiophene-2,5-diyl) (P3HT) : [6, 6]-Phenyl C61 butyric acid methyl ester (PCBM) and GaN. We traced the effect of short circuit current density with different annealing method under the various concentration and ratio of P3HT:PCBM. During the pre-annealing course, the heat treatments were performed each time at low temperature after the organic layer coated and the samples were heated at high temperature through one or two steps under the post-annealing process. It revealed that the samples with post-annealing process had higher values of short circuit current density than the other samples upon pre-annealing. And the interesting high short circuit current density features were observed at 1:1 mixing ratio and 1wt% of P3HT:PCBM.