• 한국전산유체공학회:학술대회논문집
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• 1999.05a
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• pp.177-185
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• 1999

The airfoil design optimization procedures based on the Navier-Stokes equations were developed, This procedure enables more realistic and practical transonic airfoil designs. The modified Hicks-Henne functions were used to generate the shape of airfoils. Five Hick-Henne functions were used to design upper surface of airfoil only. To enhance the ability of Hick-Henne function to generate various airfoil shape with limited number of functions, the positions of control points were adjusted through optimization procedure. The design procedure was applied to the single-point design for the drag minimization problem with lift and area constraints. The result shows the capability of the procedure to generate much realistic airfoils with very small drag-creep in the low transonic regime. This is mainly due to the viscosity effect of Navier-Stokes flow analysis. However, in the higher transonic range tile drag-creep appears. The multi-point design is shown to be an effective way to avoid the drag-creep and improve off-design performance which is very similar in the Euler design.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.5-9
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• 1989

In this paper, while 2-or 3-phase induction motor is driven with balance and no noise driving at dynamic and steady state condition. Single-phase induction motor is driven with pulsating torque except specific driving point. So we analyze the reason of producing pulsating torque with the view of unsymmetring concept. These results are applied to the design of high efficincy, high quality single-phase induction motor.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.47-50
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• 2001

Nowadays ARM7 core is used in many fields such as PDA systems because of the low power and low cost. It is a general-purpose processor, designed for both efficient digital signal processing and controller operations. But the advent of the wireless communication creates a need for high computational performance for signal processing. And then This paper has been designed a floating-point multiplier compatible to IEEE-754 single precision format for ARMTTDMI performance improvement.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1118-1124
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• 2023

Experimental study on the fluidelastic instability (FEI) of a curved tube bundle in single phase downward cross flow is investigated for the design qualification and analysis input preparation of helical coiled steam generator tubing. A 6×9 normal square curved tube array with equal and different vertical/horizontal pitch-to-diameter ratio was under-tested up to 6 m/s in term of gap flow velocity to measure the critical velocity for FEI. The critical velocity for FEI was measured at the turning point from the vibration amplitude plot along the gap flow velocity. Our test results were compared with straight tube results and published data in the design guideline. The applicability of the current design guidelines to a curved tube bundle is also assessed. We found that introducing frequency difference in a curved tube array increases the critical velocity for fluidelastic instability.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.41-43
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• 2005

The single-phase SRM(switched reluctance motor) has only one inductance variation and the positive torque is not generated in all section. So, the single-phase SRM can be started by itself if the rotor is placed at the positive slope of inductance variation by the starting device. In the previous study, equation of the magnetic force of the starting device at the acting point is derived. This paper describes the calculation of the magnetic force at the acting point by making an experiments.

• Journal of Magnetics
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• v.18 no.2
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• pp.117-124
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• 2013

Single-phase, brushless DC (BLDC) motors have unequal air-gaps to eliminate the dead-point where the developed torque is zero. Unfortunately, these unequal air-gaps can deteriorate the motor characteristics in the cogging torque. This paper proposes a novel design for a single-phase BLDC motor with an asymmetric notch to solve this problem. In the design method, the asymmetric notches were placed on the stator pole face, which affects the change in permanent magnet shape or the residual flux density of the permanent magnet. Parametric analysis was performed to determine the optimal size and position of the asymmetric notch to reduce the cogging torque. Finite element analysis (FEA) was used to calculate the cogging torque. A more than 28% lower cogging torque compared to the initial model with no notch was achieved.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.699-704
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• 2007

In this paper, optimized model was designed for the starting characteristic of the Single-Phase Line-Start Permanent Magnet Synchronous Motor by using the Design of Experiment. A field pole angle, thickness and distance from center axis of permanent magnet were selected as design factor. We executed the transient state characteristic analysis of 8 test models. The transient state characteristic analysis was executed by using the 2 dimensional Finite Element Method and the Time Difference Method. We checked the fact that the selected design factor affected starting characteristic of the Line-Start Permanent Magnet Synchronous Motor. Depend on this result we found the optimized design point by using the response optimization.

• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.218-223
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• 2008

A new Pareto-optimal design algorithm, requiring least computational work, is proposed for a single phase AC solenoid actuator with multi-design-objectives: maximizing holding force and minimizing eddy current loss simultaneously. In the algorithm, the design space is successively reduced by a suitable factor, as iteration repeats, with the center of pseudo-optimal point. At each iteration, the objective functions are approximated to a simple second-order response surface with the CCD sampling points generated within the reduced design space, and Pareto-optimal solutions are obtained by applying($1+{\lambda}$) evolution strategy with the fitness values of Pareto strength.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.430-439
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• 2004

This paper describes a design of 8192/2048-point FFT/IFFT processor (CFFT8k2k), which performs multi-carrier modulation/demodulation in OFDM-based DVB-T receiver. Since a large size FFT requires a large buffer memory, two design techniques are considered to achieve memory-efficient implementation of 8192-point FFT/IFFT. A hybrid structure, which is composed of radix-4 single-path delay feedback (R4SDF) and radix-4 single-path delay commutator (R4SDC), reduces its memory by 20% compared to R4SDC structure. In addition, a memory reduction of about 24% is achieved by a novel two-step convergent block floating-point scaling. As a result, it requires only 57% of memory used in conventional design, reducing chip area and power consumption. The CFFT8k2k core is designed in Verilog-HDL, and has about 102,000 Bates, RAM of 292k bits, and ROM of 39k bits. Using gate-level netlist with SDF which is synthesized using a $0.25-{\um}m$ CMOS library, timing simulation show that it can safely operate with 50-MHz clock at 2.5-V supply, resulting that a 8192-point FFT/IFFT can be computed every 164-${\mu}\textrm{s}$. The functionality of the core is fully verified by FPGA implementation, and the average SQNR of 60-㏈ is achieved.

• Journal of The Korea Institute of Healthcare Architecture
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• v.21 no.2
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• pp.17-24
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• 2015

Purpose: This study examines distance from nurse station to bed according to composition of single bedroom. Methods: This study has two groups of target sample ward planes. The first group has diverse patients bedroom. The other group is 36 single bedrooms and 2 3-bedrooms. The guideline of distance measurement was instituted for consistency. This study has 3 main concepts of the guideline. 1) The distance is shortcut from NS to bed. 2) The traffic line is center line between walls and center of door. 3) The start point is center of NS and the end point is bed. Results: The result of this study can be summarized into two points. The first one is that single bedroom has good privacy and longer distance from NS to bed. The second one is that weak point of single bedroom was asked ward operating system and architectural planning like as patients room, bed per unit, location of NS and plan type. Implications: Consideration Should be taken into account for the effective bedroom composition and allocation in ward. This Stuy hopefully serve as a stepping stone for the standard design of space program in ward planning.