• Journal of Magnetics
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• v.18 no.2
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• pp.207-211
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• 2013

In a coaxial magnetic gear, bridges connecting separate pole pieces are useful for fabrication and also improve mechanical reliability. However, they have a negative influence on electromagnetic performance parameters such as transmission torque and iron loss. This paper investigates the effect of stationary pole pieces connected by bridges on the electromechanical characteristics. The bridge type and thickness are the main parameters influencing the performance of a coaxial magnetic gear. The inner, center, and outer bridge types each show the best performance in terms of different characteristics. However, for any bridge type, an increase in the bridge thickness reduces the overall electromagnetic performance, except for the torque ripple, and improves the overall mechanical performance, including the deformation, von Mises stress, and natural frequency of the stationary part.

• KIEAE Journal
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• v.6 no.2
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• pp.59-66
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• 2006

Green Roof Systems are embossed that realize ecological architecture as a substantially alternative plan. So, a Purpose of the study is seeking to optimize expectation effect through the Green Roof System. we set possible object and propose the prototype on the basis of the existing Green roof System technologies. We visualize a proposed Prototype apply various materials and methods. and we analyse the effects of Green Roof System upon our City climate with use energy efficiency comparison the Green roof system with the Concrete Rooftop. We'll Provide the low data for The prospects of City climate improvement through the a ripple effect on Green Roof System and for activation of Green Roof Technology.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.330-335
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• 2013

This paper performs two kinds of Field-Oriented Control (FOC) for dual three phase permanent magnet synchronous motor (DTP-PMSM).The first is based on vector space decomposition to study the effect of current harmonics on electromechanical energy conversion. And the second presents the coupling relations between two sets of windings using two d-q transformation. And then this paper has deeply studied the differences between these two strategies, the different effect on the control of harmonic current and the reason for these differences. MATLAB-based Simulation studies of a 3KW DTP-PMSM are carried out to verify the analysis of differences between the two FOC strategies.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.9
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• pp.454-459
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• 2003

Conventional integral-slot design in permanent magnet(PM) motor tends to have a high cogging torque and large end turns, which contribute to copper losses. The fractional-slot design is effective compared to integral-slot design in the cogging torque and electromotive force(EMF) waveform. The effectiveness of fractional slot can be maximized by selecting optimal pole to slot ratio. This paper presents the effect of pole to slot ratio on the cogging torque and EMF waveform in the PM motor with fractional-slot. The effectiveness of the proposed designs has been confirmed by comparing waveform of EMF. cogging torque and torque ripple between conventional and new models.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.40-42
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• 1998

Magnetization distribution in the ring magnet for BLDC motor is generally nonuniform because the structure of mutipole magnetizer is not symmetry and the air gap is not uniform. In this paper, the effect of the nonuniform magnetization on characteristics of the motor such as torque ripple, unbalanced force and current is examined. Time stepped finite element method is used for electromagnetic field analysis.

• Journal of Food Hygiene and Safety
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• v.27 no.3
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• pp.203-208
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• 2012

In the present study, we collected the information of the 18 major food safety incidents and conducted a delphi survey with 10 experts to analyze the effect of difference between terms used in reporting of the major food safety incidents on risk communication. In the result of the analysis of information from the major food safety incidents, discord of terms used from government, local government, media and consumer groups had a tremendous effect on the socioeconomic losses and caused the expansion of the incidents. The survey with 10 experts showed that there was a high correlation between the difference in ripple effect of reporting terms and the difference in reporting terms. A correlation coefficient was 0.865. Therefore, ripple effect of incidents was significantly affected by reporting terms and we concluded that standardization of term is necessary in reporting of the food safety incidents. These results can be used as a basic material for successful risk communication among the government, enterprises and consumers.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.3
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• pp.246-251
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• 2012

This paper proposes a new position compensation method for misaligned Hall-effect sensors of BLDCM(Brushless DC Motor). If the Hall-effect sensors are installed at wrong position, the exact rotor position cannot be obtained. Therefore, when the BLDCM is controlled with this wrong position, the torque ripple can be increased and the average torque also decreases. The back-EMF of BLDCM can be obtained by using the voltage equation and by multiplying the back-EMF constant and rotor speed. At a constant speed, the estimated back-EMF by using the multiplication of the back-EMF constant and rotor speed is constant, but the estimated back-EMF from the voltage equation decreases at the commutation point because the line-to-line back-EMF of two conducting phases is start to decrease at this point. Therefore, by using the difference between these two estimated back-EMFs, the commutation point of the phase current can be determined and position compensation can be carried out. The proposed position correction method doesn't require additional hardware circuit and can be easily implemented. The validity of the proposed position compensation method is verified through several experiments.

• Journal of Korea Technology Innovation Society
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• v.14 no.4
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• pp.889-914
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• 2011

This paper is to review assessment indicator on priorities for budget allocation of the national R&D program. In priority setting of programs for the budget allocation process of the national R&D program using the Analytical Hierarchy Process (AHP), the survey result on the major influencing factors is as follows: the significance of components of evaluation for the priority of the national R&D programs in budget allocation was as following order: "accomplishment and ripple effect of the project," "basis and driving force for the promotion of project," "feasibility of project goals," and the "possibility of overlapping and linkage among projects". The importance of the final evaluation indicator was as following order: "clarity and possibility for accomplishment of business objectives," "ripple effects in terms of science and technology", "ripple effects in terms of the economy and overall society" and "appropriate correspondence with mid- to long-term plans" (the importance for these four indicators was over 10%) while the importance of "overlapping" and "appropriateness of budget size" indicators which fell below 5% were considered to be relatively less important. there is a need for a clear criteria and conceptions of evaluation indicators for budget allocation of national R&D programs.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.5
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• pp.462-473
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• 1999

This paper addresses the current measurement issue of all digital field oriented control of ac motors. The p paper focuses on the effect of low-pass filter and also on the sampling of the fundamental component of the m motor current. The low-pass filter, which suppresses the switching noise of the motor current, introduces v variable phase delay according to the current ripple frequency. It is shown that the current sampling error c consists of the fundamental component and high frL'quency ripple components. In this paper, the dependency of t this current sampling e$\pi$or on the reference voltage vector is investigated analytically and a sampling technique i is proposed to minimize the error. The work is based on the three phase symmetry pulse width modulation l inverter driving an induction machine. With this technique, the bandwidth of current regulator can be extended t to the limit given by the switching frequency of the inverter and more precise torque regulation is possible.

• Environmental and Resource Economics Review
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• v.23 no.4
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• pp.689-718
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• 2014

This study analyzes the ripple effects on the national economy of the flood damage using a perfect foresight dynamic CGE model for 2010 as the base year in case that the flood damage reduces the capital of the relevant industrial sectors. The analysis is limited to the items of physical damage such as agricultural land, ships and public facilities, for which statistical data can be obtained. As flood damage scenarios we adopt the minimum, maximum and average value of flood damage's historical data over the period 1991~2010 for each item. The results show that the largest production decline happens to the industry of fishing and transport and the next largest to the agricultural and forestry industry. The GDP reduction in the base year turns out to be from 0.001 to 0.057 percent compared to the benchmark and 11 percent compared to the exogenous shock to capital stock. Dynamically, the GDP gradually decreases until the year of 2030, which shows the long-lasting impact on the national economy of flood damage via the chanel of the capital damage.