• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.5
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• pp.626-634
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• 2018

These days, widespread use of sensitive loads and distributed generators makes static transfer switch (STS) an essential component in power circuits to achieve a good power quality for AC Grids. In case of a short-circuit fault, previous STS cannot break the fault current. However, the proposed STS has the capability of breaking it quickly as a circuit breaker. Also if there are power quality problems such as Sag/Swell, the proposed STS can quickly transfers the load to the good quality source. Furthermore it is proved that the transfer time of the proposed STS is within one half of period of 3-phase source frequency regardless of the type of load. It is anticipated that the proposed STS may be utilized to realize many stable and reliable AC grid systems.

• Journal of Institute of Convergence Technology
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• v.3 no.1
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• pp.1-8
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• 2013

High-precision surface actuator, in which in-plane motion is realized by not two-dimensional actuator superposing linear actuators but integrated planar actuator, has been developed to cope with the severe target performance like precise motion with large envelope. It is very difficult to accomplish the performance with the traditional actuating principle. So, various methods have been tried to break through the problem. This paper discusses some meaningful trials performed in the Nano Measurement and Precision Motion Control Lab. of Korea National University of Transportation.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.11
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• pp.55-63
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• 2003

In this study, an experimental research of grinding characteristics using super-abrasives for surface carburized and heat treated SCM415 materials, which were usually used to make a linear motion guide block and were comparatively hard-to-machine materials, was carried out. In order to conduct a high efficiency and a accuracy grinding of such materials, grinding processes using CBN (Cubic boron nitride) and 38P grinding wheels have been attempted on a surface grinding machine. The grindability according to each grinding conditions was evaluated by means of a grinding force, a surface roughness and a residual stress. The experimental methods and results were presented in this paper. And also, from a proposed truing method the CBN wheels that combined a copper and a break truer gave a full scope to the wheel's performance.

• Journal of Technology Innovation
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• v.12 no.1
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• pp.287-304
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• 2004

Since there are various types of technologies in the steel manufacturing industry, steel manufacturers need to adopt the most suitable technology Pricing method contingent on the technology type. Steel manufacturing technologies could be categorized as three groups. First, product and process technologies can enhance sales and contribute revenue increase, DCF method could be recommended. Second, maintenance and quality management technologies are mainly embodied in people, human resource profitability method is more suitable. Third, break-through technologies have great uncertainty in terms of commercialization and commercial success, therefore cost saving method is more reasonable. Finally, a sample case is suggested applying above technology pricing model to a steel manufacturer.

• Archives of design research
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• v.19 no.3 s.65
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• pp.71-92
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• 2006

People have their own cultural backgrounds and experiences in terms of visual perceptional thinking so that they could misunderstand the cultural symbols, trademarks, Brand Identities, and trade characters, especially, animal trademarks. Sometimes Easterners and Westerners seem to not comprehend the different meanings of the cultural symbols. The signs of twelve Chinese zodiac animals are the typical symbol of the Asian mythology. What I wanted to focus on emphasizing the different views and perspective of an animal trademark is according to the Chinese Zodiac between Eastern and Western cultures. Generally, multiple symbolisms are difficult to comprehend, because they are created by individual ideas and incorporate several mythologies and histories. How do Westerners interpret the implied meaning of Eastern animals in general? How are they going to understand the Eastern animal logos or marks accurately? How can we solve the problem to make people understand their different meanings? There were some confusing pictorial images in the area of the design field when a designer creates an animal mark for globalization and localization. Creating of hybrid symbol is the best way to break the communication barriers with people all around the world.

• Atmosphere
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• v.23 no.1
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• pp.33-37
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• 2013

In meteorology, exploitation of Kalman filter as a data assimilation system is virtually impossible due to simultaneous requirements of adjoint model and large computer resource. The other substitute of utilizing ensemble Kalman filter is only affordable by compensating an enormous usage of computing resource. Furthermore, the latter employs ensemble integration sets for evolving the background error covariance matrix by compensating the dynamical feature of the temporal evolution of weather conditions. We propose a new implementation method that works without the adjoint model by utilizing the explicit expression of the background error covariance matrix in backward evolution. It will also break a barrier in the evolution of the covariance matrix. The method may be applied with a slight modification to the real time assimilation or the retrospective analysis.

• 한국연소학회:학술대회논문집
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• 2002.06a
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• pp.3-10
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• 2002

In this work, numerical parametric studies on spray combustion have been conducted. In simulation of turbulence, RNG ${\kappa}-{\varepsilon}model$ is adopted. Initial spray distribution is specified by Rosin-Rammler distribution function. Eddy break-up model is adopted as a combustion model. The parameters considered are inlet air temperature, swirl number, and SMD. With higher inlet air temperature, the axial velocities are increased and penetration of primary jet is stronger than that of lower inlet air temperature and temperature at the exit of combustor is more uniform. Combustion efficiency is improved with high inlet air temperature. The effect of swirl number on flow field is not significant. It affect only recirculation zone. So temperature at upstream of combustor is influenced. Combustion efficiency deteriorate as SMD of fuel spray increase.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.81-91
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• 1999

Fuel characteristics of sewage sludge as required for the fluidized bed incinerators have been evaluated. Sewage sludge is basically a solid fuel with high percentage of moisture. Moisture content of the fuel directly affects the heating value of the fuel and the exhaust gas composition. When the sludge of transported into the incinerator, sludge cake is subject to the mixing, break-up and heat-up. Fluidization process would enhance these physical processes. The sludge fuel could then undergo the moisture evaporation and devolatilization process. Subsequent oxidation of volatiles as well as the remaining char would then follow. Sludge samples are characterized with high percentage of volatiles out of total combustibles. Quantitative understanding of above listed subprocesses would certainly help in the utilization of fluidized bed incinerators. A limited set of fuel characterization tests including calorimetric analysis, proximate analysis, elemental analysis and thermogravimetric analysis were conducted for the selected sludge samples. The measurement reasults of sludge samples were reported along with some published data. Limited experience in the actual incinerator plant is also presented.

• Journal of the Korean Applied Science and Technology
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• v.21 no.3
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• pp.259-266
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• 2004

Film properties of monodispersed model composite latexes with particle size of 190 nm, which consist of n-butyl acrylate as a soft phase monomer and methyl methacrylate as a hard phase monomer with different morphology was examined. Five different types of model latexes were used in this study such as random copolymer particle, soft-core/hard-shell particle, hard-core/soft-shell particle, gradient type particle, and mixed type particle. Tensile strength and tensile elongation at break of final films were evaluated. Those properties can be interpreted in terms of PBA/PMMA phase ratio and their morphology. The interfacial adhesion strength was also evaluated using $180^{\circ}$ peel strength measurement and cross hatch cutting test.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.295-300
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• 1999

In Wireless ATM Networks, the mobility management of that is used currently have been studying variously. In this paper, we show the properties of location registration, update, and handoff control mechanism of these first. And then, for frequent handoff occurring condition under minimized cellular environment by degrees, we did comparison and analysis focucing on handoff delay, call-blocking rate and call-dropping rate with communication break-time and velocity variation.