• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.7 s.250
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• pp.638-645
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• 2006

Recently, we reported that significant ion loss occurred prior to its detection in the conventional single particles mass spectrometry and more seriously the loss is ion-kinetic-energy-dependent. These lead to significant error in the measured chemical composition of nanoparticles. Here we attempted to design a novel ion optics that is capable of 100% detection of ions generated from single nanoparticle. Using a commercial software SIMION, we simulated the trajectories of ions launched at different speeds inside the previous single particle mass spectrometer We tested how affect changes in shape of repelling plate, adding Einzel lens, substitution of tube electrode between extraction and acceleration grids. As a results, we could find a best design by assembling the trials in the present condition.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.277-282
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• 1989

Xanthan gum is a biopolymer produced by Xanthomonas campestris. In xanthan gum fermentation, the fermentation broth changes to highly viscous non-Newtonian fluid as xanthan gum concentration increases. Maximum xanthan gum concentration is limited by high viscosity of the broth since mass transfers of nutrient and oxygen are inhibited. Int this study the mass transfer effects were investigated in batch and fed-batch fermentations at various agitation speeds and by separate oxygen transfer experiments. Xanthan gum production rate was observed to be largely dependent on oxygen transfer coefficient; while cell growth rate was not affected highly by this factor.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.271-278
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• 2020

The investigation into a full-scale 27 m high, by 6 m wide, thermosyphon loop. The simulation model is based on a one-dimensional axially-symmetrical control volume approach, where the loop is divided into a series of discreet control volumes. The three conservation equations, namely, mass, momentum and energy, were applied to these control volumes and solved with an explicit numerical method. The flow is assumed to be quasi-static, implying that the mass-flow rate changes over time. However, at any instant in time the mass-flow rate is constant around the loop. The boussinesq approximation was invoked, and a reasonable correlation between the experimental and theoretical results was obtained. Experimental results are presented and the flow regimes of the working fluid inside the loop identified. The results indicate that a series of such thermosyphon loops can be used as a cavity cooling system and that the one-dimensional theoretical model can predict the internal temperature and mass-flow rate of the thermosyphon loop.

• Korean Management Science Review
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• v.16 no.2
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• pp.1-11
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• 1999

A well-designed location strategy is an integral and important part of corporate strategy for retail firms. The last five years witnessed major changes in retailing industry. A growing city population, rising income levels. and the emergence of suburb areas presented ratailers with new challenges. Mass discount merchandisers and supermarkets expanded rapidly, spreading from Seoul into smaller cities. The rapid increase of mass discount stores raised new concerns and gave rise to the need from a systematic approach to location analysis. In this paper, we present the mathematical background and characteristics of DEA(Data Envelopment Analysis) model, and give a short case study where we apply the DEA model to compute the relative efficiency of 11 Korean mass discount merchandisers. Interpretation of the result is also provided.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.85-88
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• 2002

Until recently, there have been fundamental changes in many fields of industries. Especially, the mass-production is being changed into mass-customization. In order to construct a 3D e-catalog system far the utilization of mass-customization, there are several matters to consider. Setting realistic 3D image should be effective fur providing the customers with the product information with reality and raising their interest. This study explains the whole process to convert CAD data formed from the production activities into VRML data used in virtual reality environment. Examples are given and discussed to validate the proposed activity.

• International Journal of High-Rise Buildings
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• v.9 no.1
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• pp.87-93
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• 2020

Professionals who work in the realm of tall building design and construction are well aware that high-rises are the best solution for accommodating growing urban populations. Until recently, few would have thought to include tall wood buildings as part of that solution, but there is growing awareness that tall mass timber structures can help satisfy the need for density while addressing the need-equally urgent-for a more sustainable built environment. This paper examines the trend toward tall wood buildings in the United States, including their history and international influences, market drivers, structural performance, and economic viability, as well as building code changes that allow wood structures up to 18 stories. It highlights examples of mass timber projects, with an emphasis on benefits that impact return on investment.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.96-98
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• 2003

Many of research efforts have been focused on the improvement of critical current density Jc of silver-sheathed Bi-2223 tapes for practical applications of material. Bi-2223 superconducting wires with 55 filaments were fabricated by stacking, drawing process with different heat-treatment histories. After rolling process, Bi-2223 tapes were heat-treatment at 780~826$^{\circ}C$ with variable mass flow rate of mixed gas. In this study, the effect of changes in the variable mass flow rate of mixed gas during the heat treatment of Bi-2223/Ag tapes has been investigated. Distinct differences were observed in the Bi-2223 phase and critical current as flow rate of mixed gas. We could achieve proper conditions of mass flow rate of mixed gas for Ag-alloy clad Bi-2223 superconducting tapes.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.84.3-84.3
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• 2019

We investigate 3D radiation-hydrodynamics (RHD) for surface convection of the solar-type low-mass stars (M = 0.8, 0.9, and 1.0 Msun). The outer convection zone (CZ) of low-mass stars is an extremely turbulent region composed of partly ionized compressible gases at high temperature. Particularly, the super-adiabatic layer (SAL), the top of the CZ is the transition region where the transport of energy changes drastically from convection to radiation. In order to accurately describe physical processes, a realistic treatment of radiation should be considered as well as convection. As a starting model, the initial stratification in the outer envelope calculated using the solar calibrations in the context of the standard stellar theory. When the numerical fluid becomes thermally relaxed, the thermodynamic structure of the steady-state turbulent flow was explicitly collected. In this presentation, we compared thermodynamic properties of turbulent convection of the solar-type low-mass stars.

• Journal of Digital Convergence
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• v.10 no.6
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• pp.111-131
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• 2012

Mass Customization combines the advantages of mass production and customization. Mass customization has been praised as an innovative approach that would result in changes in business paradigm. However, there is no consensus on the concept of mass customization, but only a generally accepted framework exists to explain successful practices. Prior cases in mass customization are those of the small-medium sized or Internet-based companies. We in this paper explore the mass customization cases of market-leading manufacturers. Although those traditional organizations may be not for swift change, the cases of those companies are important because they target mass markets. Lampel and Mintzberg[35] proposed a continuum of strategies ranging from pure standardization to pure customization. This study investigates mass customization strategies of three companies. In this paper, the cases of cosmetics and sports shoe can be described as tailored customization, and the household appliances case can be classified as customized standardization. These three cases are compared with each other from the customers' decoupling point. Findings and implications of this research are discussed.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2004.11a
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• pp.421-422
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• 2004