• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.608-611
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• 2004

As the use of various electronic equipments has been increased recently according to industrialization and information network establishment, concern about electromagnetic wave exposed environment has also been increased. Therefore, this study aims to verify electromagnetic wave absorbing effects of inorganic paint that is made of carbon, electro-conductive materials with regard to its physical characteristics, its electromagnetic wave absorbing rate through a mock-up test for proving its effects in the indoor condition. The results are as follows: The results of running tests on electromagnetic wave absorbing inorganic paints for checking their requirements as painting material such as adherence degree, resistance to fine crack, resistance to washing, alkali-resistance, discoloration-resistance, etc. show that inorganic paints have the physical characteristics meeting the requirements for painting materials. In addition, it shows that the electromagnetic wave absorbing effect, in line with the number of paintings and the thickness of paintings, secures $75\~89\%$ of efficiency. And the mock-up test shows that the electromagnetic wave absorbing effect inside building is directly proportional to the distance from the source of electromagnetic wave such as electronic equipments.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.600-605
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• 2009

A general purpose viscous flow solver Ansys CFX is used to study a Savonius type wave energy converter in a 3D numerical viscous wave tank. This paper presents the results of a computational fluid dynamics (CFD) analysis of the effect of blade configuration on the performance of 3 bladed Savonius rotors for wave energy extraction. A piston-type wave generator was incorporated in the computational domain to generate the desired incident waves. A complete OWC system with a 3-bladed Savonius rotor was modeled in a three dimensional numerical wave tank and the hydrodynamic conversion efficiency was estimated. The flow over the rotors is assumed to be two-dimensional (2D), viscous, turbulent and unsteady. The CFX code is used with a solver of the coupled conservation equations of mass, momentum and energy, with an implicit time scheme and with the adoption of the hexahedral mesh and the moving mesh techniques in areas of moving surfaces. Turbulence is modeled with the k.e model. Simulations were carried out simultaneously for the rotor angle and the helical twist. The results indicate that the developed models are suitable to analyze the water flows both in the chamber and in the turbine. For the turbine, the numerical results of torque were compared for all the cases.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.325-328
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• 2005

EEFLs are mostly driven by sinusoidal wave driving method although EEFLs (External Electrode Fluorescent Lamps) are driven by both sinusoidal wave and square wave. The sinusoidal driving method reduces the cost and allows more power efficiency since this driving method can reduce the voltage stress of EEFL inverter switches and achieve the soft switching of the switches. And a transformer should be used in the inverter since the high voltage should be applied to the both ends of EEFL to turn on the lamp. However, the power loss mainly occurs at the transformer in the sinusoidal wave driving method. In order to remove the transformer which makes the power loss, a new method is presented. In this paper, the square wave is applied directly to the both ends of EEFL by a proposed two-stage inverter. Moreover, the luminance and power efficiency will be compared between the common sinusoidal wave driving method and square wave driving method.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.3
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• pp.74-81
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• 1996

The wave washer springs are widely used in non-return valves of fluid, especially in air check valves to confirm the rapid shut-off of valve propers. The stiffness of wave washer springs used in suction and exhaust valves of reciprocating air compressor play an important role on efficiency of the compressor. If the stiffness of the spring is too high, the pressure differences necessary to open the valves become high and the volumetric efficiency of cylinder decreasse. If the stiffness of the spring too low, the valve can not be closed rapidly and the inverse flow of air can take place. So, the optimum stiffness of valve spring is very important and it will be very helpful that the stiffness of wave washer springs to be used in suction and exhaust valves can be calculated in design stage of air compressor. In this paper the formula for calculating the spring constant of wave washer spring is introduced using bending and torsion theory of frames. The experiments are also carried out to measure the spring constants of several samples. It is proven that the calculated spring constants of wave washer springs are coincided well with measured values and that the formula presented in this paper for calculating the spring constants of wave washer spring is very useful for design of valves used in reciprocating air compressor.

• Fashion & Textile Research Journal
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• v.24 no.6
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• pp.775-781
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• 2022

As part of research to develop a permanent wave-reducing agent for hair, in the current study, 0.1%-1.0% of Polyquaternium-10 was added to a permanent reagent containing Nicotinoyl Dipeptide-23 to prepare the agent, which was tested on damaged hair. The pH change was relatively stable even after a date, but due to the hair's natural composition, 0.1%-0.6% of the Polyquaternium-10 concentration according to pH was suitable. The temperature safety experiment demonstrated it to be stable at a high temperature and at room temperature, but when a Polyquaternium-10 concentration of 0.9% or higher was added at 0℃, coagulation occurred. In terms of the force efficiency of permanent wave formation, wave efficiency lowered as the concentration increased: the longer the wave lasts, the lower the Polyquaternium-10 concentration. The permanent moisture content was found to be higher as the concentration of Polyquaternium-10 increased. Therefore, when Polyquaternium-10 is applied to the permanent wave-reducing agent, considering stability, permanent formation, durability, and moisture rate, the most suitable concentration was found to be that of Polyquaternium-10 in the cysteine-reducing agent. A novel finding from this study is that as the concentration of Polyquaternium-10 increases, the consistency of the permanent wave-reducing agent changes, shifting from a liquid to a viscous liquid formulation.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2922-2927
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• 2008

The test of engine performance using the engine dynamometer needs technical researchers and facilities. A variety of CAE analysis programs and DoE(Design of Experiments) are used to analyze data efficiently instead of tests. The study got data from simulations of WAVE that used to model the SI engine to identify performance of engine. DoE makes it possible to know effectiveness of factors for power, BSFC, volume efficiency and find optimum condition in each factor through minimizing number of experiments. CA50 has effect on power and BSFC as volume efficiency is related with cylinder liner temperature and heat coefficients. The final result in DoE could be identified of consistency above 98% after substituting the data to WAVE.

• Proceedings of the IEEK Conference
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• 2000.06d
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• pp.186-189
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• 2000

In this paper, the relation between the vibration and the sound radiated due to the piezoelectric ESWL (Extra-corporeal Shock Wave Lithotripter) is examined And the relation between the focus and the vibration of the objects is examined. The same experiments with the objects that can be breton are done and the relation between the vibration and the break efficiency of the phantom is experimentally investigated. These results show that the relativity between the power of the peak frequency and the break efficiency can be confirmed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.36 no.4
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• pp.138-148
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• 2024

Multi-resonance wave energy converter can generate efficient power generation by complexly utilizing the resonance phenomenon of waves even when waves propagate normally. As the wave is amplified by resonance, the power generation efficiency of the multi-resonance wave energy converter increases, and the shape of the resonance part needs to be optimized to maximize power generation efficiency. The multi-resonance wave energy converter amplifies waves in the seiche resonance part and the channel resonance part. In this study, CFD numerical experiments were performed under various conditions such as the length and location of the channel resonance part to analyze the sensitivity for each condition and derve the optimal shape of the channel resonance part.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.461-464
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• 2009

The characteristics of slow wave structure employed for backward wave oscillators expected to be a high power microwave source are studied analyytically. The slow wave structure is a sinusoidally corrugated wall waveguide. The waveguide is designed and fabricated by cast aluminun. The dispersion relation and transmitted characteristics for microwaves are measured in the air. There exist literatures on high efficiency of enhanced radiation from backward wave oscillators involving plasma studied experimentally.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.481-481
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• 2007

The characteristics of slow wave structure employed for backward wave oscillator expected to be a high power microwave source are studied analytically. The slow wave structure is a sinusodially corrugated wall waveguide. The waveguide is designed and transmitted characteristics for microwave are measured in the air. There exist literatures on high efficiency of enhansed radiation from backward wave oscillators involving plasmastudied experimentally another results.