• 한국표면공학회지
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• 제27권3호
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• pp.149-157
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• 1994

The formation of spangles on a hot dip galvanized sheet steel by spray cooling the molten zinc coating with air, water and 2.0wt% $NH_4H_2PO_4$ solution has been studied performing laboratory experiments, and their coating properties have been evaluated. Minimized spangles were easily formed by mist spraying the solution for 1 second at the low nozzle spray pressure onto the molten zinc at 420~$422^{\circ}C$ because the solute $NH_4H_2PO_4$ in the sprayed solution imparted a highly rapid cooling effect to the coating through its endothermic de-composition reactions and because the decomposed products acted as numerous nucleation sites for the mini-mized spangles on the coating. Good surface appearances sand sound coating properties were obtained on this coating. Only regular spangles were formed on the coating by the forced convective air cooling. At the high nozzle spray pressure, zero spangles were formed on the coating by the pure water spray cooling. However, the coating had a dull and rough surface with craters sand cracks.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.146-148
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• 2003

SrZrO$_3$ resistive oxide barriers on Ag sheathed Bi2223 monocore tapes were prepared by the sol-gel and dip coating method to reduce AC coupling loss. The performance of the dip-coated SrZrO$_3$ thin films was evaluated in terms of bond strength and surface microstructure by varying the amount of PVP (polyvinylpyrrolidone) binder. Although bond strength and coating thickness increased as the PVP content rose, surface microcracking was more severe for the specimen containing higher content of PVP binder. It suggests that coating thickness and microcracking of the SrZrO$_3$ films on Bi2223 tapes was governed primarily by the amount of PVP binder.

• 한국전기전자재료학회논문지
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• 제21권4호
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• pp.341-347
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• 2008

Laminated LTCC components of high integrity, fabricated by thick film process, are applied to industrial field of IT technology along with miniaturization trend of electronic devices. Dispersion states were examined by several evaluation methods with MLS-22, which is one of commercial LTCC powders, to achieve optimal dispersion as basis for stable LTCC fabrication process. Slurry viscosity, surface roughness of dip-coated slide glass, sedimentaion of slurry, and SEM observation of dried surface were utilized with respective amount change of various commercial dispersants. Among these commercial dispersants, optimal dispersion state was obtained with 0.4 wt% of BYK-111, from the results of various evaluation methods.

• 디지털산업정보학회논문지
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• 제5권4호
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• pp.127-137
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• 2009

This paper is proposed that in-output Digital module is acquired a vibration signal of a rotating machinery by Data Acquisition System. The module is designed to get ride of nose through low pass filter on the vibration signal from sensors and set the gain value for being able to sampling AC to DC, and also the sampled data by sampler and the conversed data by DIP/FPGA is supplied to the analyzer for analysis at a software tool. The DIP(Digital Signal Processor) of the Digital input/output Board makes Average voltage, Peak to Peak voltage, RMS(Root Mean Square) and Gap voltage, also FFT(Fast Fourier Transform) for rotating vibration diagnosis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1360-1363
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• 1994

Epoxy resin insulator have good electrical properties (high electric strength, high resistivity, low dielectric loss) in addition to high mechanical strength, small dimensions and design versatility. Polymer insulator, however, are subjected to aging processes, caused by the surrounding atmosphere, which may lead to degradation of their properties. This paper describes the results of a important study on the artificial pollution test, Weather-Ometer properties and rotating wheel dip test of high voltage different aging insulators which are the most important factors for outdoor uses. Also, the objects of this paper are to (a)result of insulator under dry(wet) flashover voltage, (b)artificial pollution test of salt spay, (c)Accelerated aging test of Weather-Ometer, (d) wet and dry flashover voltage under rotating wheel dip test.

• 한국표면공학회지
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• 제31권2호
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• pp.101-108
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• 1998

The effect of oxidation-reduction heating conditions on coating adherence of hot-dip galvanized steel containing silicon has beeninvestigated. The presence of a stbke sillicon oxide formed on the steel surface has been shown to be very detrimenal to proper wetting by liquid zinc. When the steel has more than the critical sillicon content neeled to from a stable external oxide, the use of oxidation-reduction method has been found successful in obtaining a good quality, coated product with excellence adhreence. This can be explained by the formation of an iron oxide. The iron oxrtion of the scale is reduced, leaving the stable oxides dispersed in a fresh metallic iron surface layer. This reduced iron surface is easily wetted by the liquid zinc and excellent adherence is obtained.

• The Korean Journal of Ceramics
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• 제1권4호
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• pp.219-223
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• 1995

Ceramic membranes of the supported $TiO_2-CeO_2$ were prepared by dip-coating method on an $\alpha-Al_2O_3$ porous substrate. The mean pore diameter of an alumina support was 0.125 um. The mean particle diameter of $TiO_2-CeO_2$ top layer varied with firing temperature and ranged from 20 to 85 nm. The thermal stability of the composite membranes was studied from their surface microstructure after calcination at $600-900^{\circ}C$. The supported $TiO_2-CeO_2$ composite membranes exhibited much higher heat resistance than the $TiO_2$ membrane.

• 한국세라믹학회지
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• 제34권7호
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• pp.747-757
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• 1997

ZSM-5 zeolite composite membranes have been synthesized from a silica sol solution containing TPABr as an organic template by the dip-coating and the pressurized-coating hydrothermal treatment techniques. The CO2 separation efficiency of synthesized composite membranes was also investigated. The permeation mechanism of CO2 through ZSM-5 membranses was the surface diffusion, and that of N2, O2, and He gases was Knudsen diffusion or activated diffusion depending on the synthetic method of membranes and the measurement temperature. The CO2/N2 separation factor of the membrane prepared by the dip-coating hydrothermal treatment was 2.5 at about 12$0^{\circ}C$, while the ZSM-5 composite membrane synthesized by the pressurized-coating hydrothermal treatment technique showed the CO2/N2 separation factor of 9.0 at room temperature higher than that ever reported in the literature.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.354-355
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• 2018

Flywheel energy storage system (FESS) operates motor or generator by utilizing the stored kinetic energy in the rotating mass. Thus, the FESS can support the frequency control of the power system. However, the FESS is disabled when the rotor speed reaches to its minium value. Thus, the second frequency dip occurs in the power system. This paper proposes the frequency control scheme of FESS based on a variable gain depending on the rotor speed and frequency deviation. The proposed scheme prevents the second frequency dip because the variable gain decreases depending on the stored in the FESS. The performance of the proposed scheme is investigated for the IEEE 14-bus system.

• Corrosion Science and Technology
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• 제9권2호
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• pp.67-73
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• 2010

Niobium microalloying is effective in hot-rolled and cold-rolled steels by providing a fine-grained microstructure resulting in increased strength. To optimize the strengthening effect, alloy design and hot-rolling conditions have to be adapted. As a key issue the dissolution and precipitation characteristics of Nb are discussed in particular with regard to the run-out table conditions. It is then considered how the hot-rolled microstructure and the solute state of Nb interact with the hot-dip galvanizing cycle. The adjusted conditions allow controlling the morphology and distribution of phases in the cold-rolled annealed material. Additional precipitation hardening can be achieved as well. The derived options can be readily applied to produce conventional HSLA and IF high strength steels as well as to modern multiphase steels. It will be explained how important application properties such as strength, elongation, bendability, weldability and delayed cracking resistance can be influenced in a controlled and favorable way. Examples of practical relevance and experience are given.