• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.701-706
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• 2002

Typically, dimensions of the power circuit depend on magnetic components, heat sink, and smoothing capacitor, etc. For the miniaturization of the power circuit, one of the solutions is that bulky magnetic transformer in previously used is replaced by a piezoelectric transformer. Therefore, since many systems are attempted to apply the piezoelectric transformers, a new piezoelectric material is tending to be developed continuously. In this paper, an analysis of neon tube inverters with piezoelectric transformers are presented by Pspice modeling. Simulation results show that it is possible to apply a piezoelectric transformer to neon tube inverters with high conversion efficiency

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.95-97
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• 2012

Recycled aggregate (RA) produced from demolished concrete waste can bring about several problems on concrete performance, when it is used as aggregate for new concrete. Because RA generally has lower quality than natural aggregate due to the residual cement paste attached on RA and various impurities. It is also very difficult to ensure that the quality of RA remains consistent, because generally RA is produced variously. Thus, in concrete recycling, it is extremely important to estimate the risk of the impurities which could affect performances of recycled aggregate concrete (RAC) focusing on the material flow of concrete waste and its recycling. This study suggests an evaluation result to expect the possibility of impurity mixing in RA production procedure. and suggests a risk evaluation model to expect the changes of RAC performances based on conventional data in Japan.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.107-110
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• 2004

Application of aluminum alloy has been increasing for most of industry area because aluminum has a good mechanical properties and castability, especially automotive field for weight reduction. But, Furnace industry is sluggish. The purpose of this study is numerical analysis of aluminum holding furnace for reasonableness estimation when we design for new model of furnace. The numerical simulation involving fluid flow of inside air and heat transfer to fireproof material is presented in order to improve the understanding of aluminum furnace. First of all, we are carried out numerically for the two dimensional inside convection and surface radiation heat transfer in a square enclosure. Subsequently, we are established the analysis method of aluminum furnace considering natural convective heat transfer

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.8-13
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• 2000

In this paper, a new adaptive cross-coupling control (CCC) method with an improved contour error model is proposed to maintain contouring precision in high-speed nonlinear contour machining. The proposed method utilizes variable controller gains based on the instantaneous curvature of a contour and the feedrate command. In addition, a real-time federate adaptation scheme is included in the proposed CCC to regulate cutting force. The proposed method is evaluated and compared with the conventional CCC for nonlinear contouring motion through computer simulations. The simulation results show that the proposed CCC improves the contouring accuracy and regulates cutting force more effectively than the existing method.

• Transactions of Materials Processing
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• v.1 no.1
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• pp.52-65
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• 1992

In this study a new simplified three-dimensional numerical method and the associated computer program have been developed to simulate the non-axisymmetric extrusion processes. The two-dimensional rigid-plastic finite element method under the generalized plane-strain condition is combined with the slab method. To define the die geometry for a non-axisymmetric extrusion. area mapping technique was used. Streamlined die surface was used to minimize the total extrusion pressure. Extrusion of square, hexagonal and 'T' section from round billet have been simulated and experimented with a model material. The computed results were in good agreement with the experiments in cross-sectional grid distortion. Computational results will be valuable for designing tool geometries and corresponding processes.

• Journal of Information Science Theory and Practice
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• v.1 no.2
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• pp.84-92
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• 2013

In this study, the properties of the object types required to describe the relationship among research data resources, which may be generated during the life cycle of the research, are derived. The properties of Fedora Commons and DSpace, which are open source software used for resource management, and schema properties published in DataCite were analyzed. Based on relation names of Fedora Commons, nine new relation names were derived. Thirty-eight object type properties consolidating the target properties of the analysis were derived. The result of this study can be used as basic material for crosswalk research studies of object type relation terms to ensure interoperability among the systems.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1441-1446
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• 2008

Seoul Metro Line 9 (SML9) is the first subway line that private capital invests in Korea. SML9 will cross Seoul, linking the Gimpo Airport to the Gangnam district (25.5km) opening in the first half of 2009. SML9 has a new model in Korea constructed by metropolitan government and private company and operated by specialized public transportation service provider. SML9 is confronted with tough environment of stagnated public transportation and strong competitor, Olympic city expressway. And SML9 is under pressure for showing high efficiency as non-governmental organization from both customers and government. Consequently SML9 must lead the maximum efficiency by using its material and human resource. It is necessary that SML9 raise a competitive power and display its ability in active collaboration with relative organization and company. Hereupon, I propose renovation plans from viewpoint of operation field of SML9, (1) efficient train scheduling regime focusing on the combination of express and local train (2) close connection of other mean of transportation and (3) effective connection convention with Airport Railroad (AREX) as the line connected directly.

• Corrosion Science and Technology
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• v.9 no.4
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• pp.159-163
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• 2010

Precise coating weight control is very important issue on quality and minimizing operating costs on continuous galvanizing line. These days, many steel making companies are having a new understanding of cost importance by rise raw material prices and customer's requirement for cost reduction. Dongbu steel also meets these situations and decided to develop the technologies. Dongbu Steel developed Integrated coating weight control system jointly with Objective Control Ltd. and installed 2CGL and 4CGL. Several technological functions were developed and realized to achieve true hands-off operation and maximum cost benefit by combining model-based preset and dynamic prediction models. We also installed it on 1 CGL on April, 2008. This paper will present the interface, functions and application result of the integrated coating weight control system including Zn saving and coating weight uniformity.

• Journal of Astronomy and Space Sciences
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• v.5 no.2
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• pp.81-96
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• 1988

We have made new models for mass-losing OH/IR stars to explain the properties of the dust shells around them using more accurate information about the material in the shell and the physical precesses including pulsations. We have applied our dust opacity which has been deduced from observations and experimental data to various density distributions, calculated the model emergent spectra, and compared with observations. Contrary to previous suggestions, we could fit observations fairly well using density distribution $\rho\propto r^{-2}$, which is physically plausible, with proper choice of opacities. The time scales for dust formation, growth, and movement are calculated to be compared with pulsation periods. The change of the emergent spectrum depending on the phase of pulsation can be explained fairly well by changing dust condensation radius(for fixed dust condensation temperature) in step with the change in stellar luminosity. The effects of stellar wind models and pulsation models on dust shells with attention to emergent spectra are discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.362-367
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• 2003

A new mechanical-electrical hybrid passive dam ping treatment is proposed to improve the performance of structural vibration control. The proposed hybrid passive damping system consists of a constrained layer damping treatment and a shunt circuit. In a passive mechanical constrained layer damping, a viscoelastic material damping layer is used to control the structural vibration modes in high frequency range. The passive electrical damping is designed for targeting the vibration amplitude in the low frequency range. The governing equations of motion are derived through the Hamilton's principle. The obtained mathematical model is validated experimentally. The presented theoretical and experimental techniques provide invaluable tools for controlling the multiple modes of a vibrating structure over a wide frequency band.