• Journal of Power Electronics
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• v.10 no.6
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• pp.709-716
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• 2010

MDPS (motor driven power steering) systems have been widely used in vehicles due to their improved fuel efficiency and steering performance when compared to conventional hydraulic steering. However, the reduction of torque ripples and material cost are important issues. A low resolution position sensor for MDPS is one of the candidates for reducing the material costs. However, it may increases the torque ripple due to the current harmonics caused by low resolution encoder signals. In this paper, the torque ripple caused by the quantized rotor position of the low resolution encoder is analyzed. To reduce the torque ripples caused by the quantization of the encoder signals, the rotor position and the speed are estimated by measuring the frequency of the encoder signals. In addition, the compensating q-axis current is added to the current command so that the 6th order torque harmonic is attenuated. The reduction of torque ripples by applying the estimated rotor position and the compensated q-axis current is verified through experimental results.

• Journal of Korea Planning Association
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• v.53 no.6
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• pp.101-116
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• 2018

Paying an attention to the issue of energy poverty of low-income households and ensuing regressivity of energy consumption, this study empirically analyzes the effects of both household and housing characteristics on heating energy consumption in an integrated way and identifies their causal structure based on the 2016 Korea Housing Survey data provided by the Korean government. Multiple regression analysis shows that household income and deteriorated level of housing, such as age and degree of cracks have positive effects and floor area of housing has a negative effect on the heating energy consumption per unit area of housing (HECPUH). Path analyses further reveal that the direct effect of household income on HECPUH is offset by the indirect effects that are mediated by deteriorated level and floor area of housing, making the total effect statistically insignificant. As a result, there is no significant difference in HECPUH across all income strata, implying that low-income (high-income) households pay more (less) heating costs relative to their income level, since they reside in the houses with relatively low (high) energy efficiency. To deal with this regressive causal structure of energy consumption, a policy option is recommended to improve energy efficiency of low-income housing through the government assistance in its maintenance and repair.

• Journal of Broadcast Engineering
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• v.28 no.1
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• pp.21-30
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• 2023

Computer-generated holography requires much more computation costs and memory space rather than image processing. We implemented the diffraction calculation with low-precision and mixed-precision floating point numbers and compared the processing time and quality of the hologram with various precision. We compared diffraction quality with double, single and bfloat16 precision. bfloat16 shows 5.94x and 1.52x times faster performance than double precision and single precision. Also, bfloat16 shows lower PSNR and SSIM and higher MSE than other precision. However, there is no significant effect on reconstructed images. These results show low precision, like bfloat16, can be utilized for computer-generated holography.

• Progress in Superconductivity and Cryogenics
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• v.25 no.3
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• pp.13-17
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• 2023

Magnetic separation technology for small paramagnetic particles has been desired for the volume reduction of contaminated soil from the Fukushima nuclear power plant accident and for the separation of scale and crud from nuclear power plants. However, the magnetic separation for paramagnetic particles requires a superconducting high gradient magnetic separation system applied, hence expanding the bore diameter of the magnets is necessary for mass processing and the initial and running costs would be enormous. The use of high magnetic fields makes safe onsite operation difficult, and there is an industrial need to increase the magnetic separation efficiency for paramagnetic particles in as low a magnetic field as possible. Therefore, we have been developing a magnetic separation system combined with a selection tube, which can separate small paramagnetic particles in a low magnetic field. In the previous technique we developed, a certain range of particle size was classified, and the classified particles were captured by magnetic separation. In this new approach, the fluid control method has been improved in order to the selectively classify particles of various diameters by using a multi-stage selection tube. The soil classification using a multi-stage selection tube was studied by calculation and experiment, and good results were obtained. In this paper, we report the effectiveness of the multi-stage selection tube was examined.

• Journal of the Korean Society of Radiology
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• v.8 no.3
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• pp.97-103
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• 2014

Decommission of medical cyclotron give rise to a lot of low-level radioactive waste and costs. Decommissioning cost should be reasonably calculated according to the decommissioning activities and installed components of facilities. In this paper, we investigated the experience on the cyclotron relocation from SNUH(Seoul National University Hospital) to SKKU(Sungkyunkwan University) and analyzed radioactive waste management costs by applying the disposal scenarios. Also considerations for decommissioning cost estimation are reviewed. The results could be utilized as a basic data for establishment on the methodology of decommissioning cost estimation and evaluation.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.11
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• pp.1629-1636
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• 2011

Global pork markets are becoming more competitive, riding the wind of the bilateral free trade agreement. China is the world's largest pork producer with nearly 50% of the world's total production. China's fast growing economy has provided its people with higher purchasing power, resulting in a rapid expansion of the Chinese swine industry over the past decades. Worldwide, China consumes the greatest amount of pork and it is believed that this trend will continue. Japan is the world's largest pork importing country, even though it also produces a lot of pork. The Japanese swine industry encounters weighty obstacles in production costs and environmental limitations which result in reduced domestic supply and creates the situation in which Japan has to import a significant amount of pork for their consumption. South Korea is also a large buyer of pork, with a status greatly influenced by the struggle that the country has faced with Foot and Mouth Disease (FMD) which occurred in 2000, 2002 and 2010. High production costs, low production efficiency, and forced culling following the FMD outbreak resulted in the loss of many hog farming households in the country, reducing supply of domestic pork in the face of continued demand. Overall, pork production in these economically important countries can greatly impact the industry globally. The goal of this review paper is to describe pork production in China, Japan, and South Korea and discuss these countries' role in global pork export markets.

• The Korean Journal of Community Living Science
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• v.28 no.3
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• pp.429-446
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• 2017

The current study aims to identify factors associated with private tutoring of college students in Korea. For this purpose, this study used the Korean Education and Employment Panel survey, which contains items regarding whether or not college students receive private tutoring as well as the monthly costs of private lessons. The current study focuses on private English lessons due to the very low response rates of other types of private tutoring. For the analysis, the 5th wave of KEEP collected in 2008 was selected, and a Heckman selection model was employed, including three categories of variables: individual, school, and parent/household factors. The results have revealed that for the selection model (receiving private English tutoring or not), having received private lessons in high school, gender, and level of satisfaction regarding the respondent's current university were significant. In terms of the outcome model (cost for private English tutoring in college), university admission type (rolling vs. regular), living with parents, school type (4-yr university vs. others), being in debt to cover private lesson fees in high school, and monthly household income had significant effects. This article also discusses the results and implications for future research and policy makers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.2
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• pp.637-658
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• 2015

The development of multimedia applications has followed the development of high-speed networks. By improving the performance of mobile devices, it is possible to provide high-transfer-speed broadband and seamless mobile multicasting services between indoor and outdoor environments. Multicasting services support efficient group communications. However, mobile multicasting services have two constraints: tunnel convergence and handoff latency. In order to solve these problems, many protocols and handoff methods have been studied. In this paper, we propose inter local mobility anchor (inter-LMA) optimized handoff model for mobile multicasting services in proxy mobility IPv6 based (PMIPv6-based) networks. The proposed model removes the tunnel convergence issue and reduces the router processing costs. Further, it the proposed model allows for the execution of fast handoff operations with adaptive transmission mechanisms. In addition, the proposed scheme exhibits low packet delivery costs and handoff latency in comparison with existing schemes and ensures fast handoff when moving the inter-LMA domain.

• KDI Journal of Economic Policy
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• v.25 no.1
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• pp.3-54
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• 2003

This paper studies the effects of the special surcharge on deposits, proposed as a plan to finance the costs of restructuring Korean corporate and financial sectors. Specifically, the study analyzes the change in the autonomous behavior of economic agents in terms of cost transfer and substitution effects. Given the result that the growth rate of deposits does not respond to the change of interest rates so much as that of loans, financial institutions have more incentive to transfer the costs incurred by the special surcharge to depositors. This paper also reports that the portfolio of households show a noteworthy feature that insured deposits have a relatively small portion in terms of total assets for high-asset class households, whereas most assets for low-asset class households are subject to the special surcharge.

• International Journal of Internet, Broadcasting and Communication
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• v.9 no.2
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• pp.1-10
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• 2017

The high costs of electric vehicle supply equipment (EVSE) and installation are currently a stumbling block to the proliferation of electric vehicles (EVs). The cost-effective solutions are needed to support the expansion of charging infrastructure. In this paper, we develope EV charging system based on the big data analysis of the power consumption patterns. The developed EV charging system is consisted of the smart EV outlet, gateways, powergates, the big data management system, and mobile applications. The smart EV outlet is designed to low costs of equipment and installation by replacing the existing 220V outlet. We can connect the smart EV outlet to household appliances. Z-wave technology is used in the smart EV outlet to provide the EV power usage to users using Apps. The smart EV outlet provides 220V EV charging and therefore, we can restore vehicle driving range during overnight and work hours.