• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.447-456
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• 1995

As a part of electro-mechanical totally implantable artificial heart (TIAH) program, a transcut- aneous energy transmission system has been developed. By mutual magnetic induction between the first coil on the skin and the subcutaneously implanted second coil, the system transfers elctrical power through the skin. This research aimed at minimizing the size of the implanted part as well as maximizing the transfer efficiency. Using class I amplifier, we achieved above 75% power transfer efficiency at average 40W power transfer level which is required for normal TIAH operation. In vivo performance of the developed system and bio-compatibility of the material used in Implanted parts were evaluated through animal experiments.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.8
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• pp.547-555
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• 2008

The effects of paper properties such as density, air permeability, water vapor transmission rate on the thermal performance of plate-type enthalpy exchanger were experimentally investigated. Papers having different properties were made from the same pulp by calendering or refining. Enthalpy exchanger samples were made from the papers, and were tested according to the standard test procedure (KS B 6879). Effective efficiencies were obtained, which accounted for the air leakage between supply and exhaust streams. Results showed that paper density affected the sensible heat transfer of the samples. Sensible heat transfer increased with density of the paper. It was also shown that effective efficiency of latent heat transfer was approximately the same independent of the samples, which suggests that papers made of the same pulp show similar water vapor transmission characteristics independent of the degree of calendering or refining. Best performance was obtained for the sample having highest paper density and moderate water vapor transmission ratio.

• The Journal of Korean Physical Therapy
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• v.12 no.1
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• pp.163-172
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• 2000

The purpose of this study was to provide experimental evidence and theoretical background for the applicability of bilateral transfer paradigm to the rehabilitation programs for children with hemiplegic cerebral palsy. Children with hemiplegia, which means unilateral motor disabilities, display abnormal motor and postural patterns of the affected side due to hemiparesis, spasticity, and sensory disorders, resulting in a decreased motor abilities of the affected side compared to unaffected side. Accordingly, they tend to rely on the unaffected limb for everyday activities, which further deteriorates the functions of the affected side by causing associated reaction, abnormal postural patterns, and hypertonus. Rehabilitation programs developed for children with hemiplegic cerebral palsy include neurodevelopmental treatment, application of cast or splint to unaffected limb, neuromuscular electrical stimulation, and task oriented model. These programs, however, have several drawbacks, such as discontinuity in treatment effect and psychological hatred to the force use of the affected side. In order to solve these problems and enhance the efficiency of the rehabilitation programs, it is required to maximize the use of the affected side without hatred. Characteristics of the control system, such as temporal coupling and spatial assimilation between limbs and neural crosstalk at different levels of central motor pathway, suggest that the bilateral transfer paradigm may enhance the efficiency of the rehabilitation programs for children with hemiplegic cerebral palsy.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.25-26
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• 2015

Inductive Power Transfer (IPT) method becomes more and more popular for the Electric Vehicle (EV) battery charger due to its convenience and safety in comparison with plugged-in charger. In recent years, Lithium batteries are increasingly used in EVs and Constant Current/Constant Voltage (CC/CV) charge needs to be adopted for the high efficiency charge. However, it is not easy to design the IPT Battery Charger which can charge the battery with CC/CV charge under the wide range of load variation due to the wide range of variation in its operating frequency. This paper propose a new design and control method which makes it possible to implement the CC/CV mode charge with minimum frequency variation (less than 1kHz) during all over the charge process. A 6.6kW prototype charge has been implemented and 96.1% efficiency was achieved with 20cm air gap between the coils.

• Journal of Power Electronics
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• v.19 no.1
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• pp.211-219
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• 2019

In magnetically coupled resonant (MCR) wireless power transfer (WPT) systems, the introduction of additional intermediate coils is an effective means of improving transmission characteristics, including output power and transmission efficiency, when the transmission distance is increased. However, the position of intermediate coils in practice influences system performance significantly. In this research, a three-coil MCR WPT system is adopted as an exemplification for determining how the spatial position of coils affects transmission characteristics. With use of the fundamental harmonic analysis method, an equivalent circuit model of the system is built to reveal the relationship between the output power, the transmission efficiency, and the spatial scales, including the axial, lateral, and angular misalignments of the intermediate and receiving coils. Three cases of transmission characteristics versus different spatial scales are evaluated. Results indicate that the system can achieve relatively stable transmission characteristics with deliberate adjustments in the position of the intermediate and receiving coils. A prototype of the three-coil MCR WPT system is built and analyzed, and the experimental results are consistent with those of the theoretical analysis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.1
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• pp.36-45
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• 2010

In this paper, we propose a new design method to design a wireless power transfer system using loop antennas for consumer electronics. This method can simply design a wireless power transfer system only using measurements of coupling coefficients and simple equations of equivalent circuit model about loop antennas without complicated electromagnetic analysis. Using the proposed design method, a wireless power transfer system with a pair of loop antennas operating at the frequency of 13.56 MHz, which have a dimension of $50{\times}50\;cm^2$, is designed and implemented. The input return loss, coupling coefficient, efficiency, and input impedance variation with respect to a distance between loop antennas were measured. The proposed design method provides good agreements between measured and predicted results. Also, the wireless power transfer system with impedance matching circuits designed by the proposed design method shows two times higher efficiency characteristics than the case with the general $50\;{\Omega}$ impedance matching circuits. Therefore, we verified that our design method could be an effective tool to design a wireless power transfer system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.5
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• pp.1035-1041
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• 2017

In magnetic resonance-based wireless power transfer (WPT) systems, frequency splitting phenomenon, in which power transfer efficiency (PTE) decreases seriously as resonators are close to each other, is the problem that we should address for reliable power transfer in short distance. In this paper, we present WPT systems using an equivalent circuit model and analyze PTE and marginal coupling coefficient ($k_{split}$) where the frequency splitting occurs. In addition, we perform circuit-level simulations using Advanced Design System, and show that the achievable PTE is different for the structures of resonators when k>$k_{split}$. We confirm that higher PTE can be ensured as k increases in the case of identical resonators, while PTE is degraded as k increases in the case of non-identical resonators. Therefore, in short distance, in which k>$k_{split}$, it is more efficient for achieving reliable PTE to use identical resonators rather than non-identical resonators.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.2
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• pp.31-40
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• 2017

In this paper, we compared the efficiencies of national R&D investments between NT (Nanotechnology) areas in terms of papers, patents, and commercializations, and found ways to improve the efficiencies of national R&D investments for each NT area. This is in response to huge R&D investments government has made recently in NT areas. Here, we collected data on investments, papers, patents, and commercializations for the R&D projects in NT areas through National Science & Technology Information Service. Based on the data, we analyzed the investment and performances (papers, patents, and commercializations) for each NT area, calculated the efficiency for each NT area, and compared the efficiencies between NT areas. Next, using cluster analysis, we identified several NT areas with similar characteristics in terms of paper efficiency, patent efficiency and commercialization efficiency. Finally, we derived implications for the efficiency enhancement for each grouping. The cluster analysis showed that there could be two groups, one being low in terms of technological outcome (papers and patents) efficiencies and high in terms of commercialization efficiencies, while the other being high in terms of technological outcome (papers and patents) efficiencies and low in terms of commercialization efficiencies. Therefore, the strategy for one group calls for support for technology transfer or technology introduction from other R&D performers and grant of guidance for improving R&D performers' commercialization ability to other R&D performers while the strategy for the other group calls for R&D support for transfer of technology to other R&D performers, activation of technology transfer and support for commercialization of R&D performers.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1421-1430
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• 2022

The computation of the solid angle and the detector efficiency is considering to be one of the most important factors during the measuring process for the radioactivity, especially the cylindrical γ-ray NaI(Tl) detectors nowadays have applications in several fields such as industry, hazardous for health, the gamma-ray radiation detectors grow to be the main essential instruments in radiation protection sector. In the present work, a generic numerical simulation method (NSM) for calculating the efficiency of the γ-ray spectrometry setup is established. The formulas are suitable for any type of source-to-detector shape and can be valuable to determine the full-energy peak and the total efficiencies and P/T ratio of cylindrical γ-ray NaI(Tl) detector setup concerning the truncated conical radioactive source. This methodology is based on estimate the path length of γ-ray radiation inside the detector active medium, inside the source itself, and the self-attenuation correction factors, which typically use to correct the sample attenuation of the original geometry source. The calculations can be completed in general by using extra reasonable and complicate analytical and numerical techniques than the standard models; especially the effective solid angle, and the detector efficiency have to be calculated in case of the truncated conical radioactive source studied condition. Moreover, the (NSM) can be used for the straight calculations of the γ-ray detector efficiency after the computation of improvement that need in the case of γ-γ coincidence summing (CS). The (NSM) confirmation of the development created by the efficiency transfer method has been achieved by comparing the results of the measuring truncated conical radioactive source with certified nuclide activities with the γ-ray NaI(Tl) detector, and a good agreement was obtained after corrections of (CS). The methodology can be unlimited to find the theoretical efficiencies and modifications equivalent to any geometry by essential sufficiently the physical selective considered situation.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2285-2290
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• 2007

The main objective of this study is to analyze the heat transfer characteristics in the electric melting furnace. Local temperatures are measured at various location in the furnace using the B-type thermocouples. In this paper, the numerical simulation was performed using the ANSYS software, and compared with experimental data. Mathematical heat transfer model for the prediction of temperature distribution has been developed by considering the thermal radiation among heating element, crucible and insulating materials. The results show that the temperature distributions predicted by the numerical simulation agree with experimental results comparatively.