• Proceedings of the Technology Innovation Conference
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• 2002.02a
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• pp.59-89
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• 2002

The rapid diffusion of information and telecommunication (IT) technologies during the recent decennia produced fundamental changes in the economic activity at a global level, resulting in what became coined as the "new economy". However, empirical evidence on the contribution of IT equipment to growth and productivity is at best mixed, with the more or less consistent results on the positive link between the two relating to the United States in the 1990-s. Although the empirical literature on the link between IT investment and economic performance employs a wide variety of methodologies, the overwhelming majority of the studies appears to be employing the assumption of linearity of the IT-performance relationship and predominantly explores the direct nature thereof. In this study we relax both these assumptions and find that the indirect, or aggregate productive efficiency, effects of IT investment are as important as are the direct ones The estimated non-linear nature of the indirect relationship between IT investment intensity and productive efficiency accommodates the concepts of critical mass and complementary (infrastructure) capital offered in the literature. Our key finding is that the world economy′s average level of IT investment intensity remained below the estimated critical mass. Since in this study we developed a methodology that allows one to explicitly measure the critical mass of IT investment intensity, its individual estimation at a country or industrialsector level may help evaluate the extent to which IT investment activity has to be encouraged or discouraged.

• International Journal of High-Rise Buildings
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• v.12 no.2
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• pp.145-152
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• 2023

Typical floor systems in contemporary tall buildings consist of reinforced concrete or composite metal deck over framing members and account for a majority of the structural weight of the building. The use of high-density materials, such as reinforced concrete and steel, increases the weight of floor systems, reducing the system's overall efficiency. With the introduction of high-performance materials, mainly mass timber products, and fiber-reinforced composites, in the construction industry, designers and engineers have multiple options to choose from when selecting structural materials. This paper discusses the application of mass timber and carbon fiber composites as structural materials in floor systems of tall buildings. The research focused on a comparative analysis of the structural system efficiency for five different design options for tall building floor systems. Finite Element Analysis (FEA) method was adopted to develop a simulation framework, and parametric structural models were simulated to evaluate the structural performance under specific loading conditions. Simulation results revealed the advantages of lightweight structural materials to improve system efficiency and reduce material consumption. The impact of mechanical properties of materials, loading conditions, and issues related to fire engineering and construction were briefly discussed, and future research topics were identified in conclusion.

• Food Science of Animal Resources
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• v.42 no.1
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• pp.1-17
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• 2022

Lipids are one of the major macronutrients essential for adequate growth and maintenance of human health. Their structure is not only complex but also diverse, which makes systematic and holistic analyses challenging; consequently, little is known regarding the relationship between phenotype and mechanism of action. In recent years, rapid advancements have been made in the fields of lipidomics and bioinformatics. In comparison with traditional approaches, mass spectrometry-based lipidomics can rapidly identify as well as quantify >1,000 lipid species at the same time, facilitating comprehensive, robust analyses of lipids in tissues, cells, and body fluids. Accordingly, lipidomics is now being widely applied in various fields, particularly food and nutrition science. In this review, we discuss lipid classification, extraction techniques, and detection and analysis using lipidomics. We also cover how lipidomics is being used to assess food obtained from livestock and poultry. The information included herein should serve as a reference to determine how to characterize lipids in animal food samples, enhancing our understanding of the application of lipidomics in the field in animal husbandry.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.95-101
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• 2004

An experimental investigation was conducted to investigate the effects of the equivalence ratio and air mass flux on the combustion efficiency in a solid fuel ramjet used fuel grains which were highly loaded with boron carbide. Combustion efficiency increased with increasing equivalence ratio (grain length), and decreasing air mass flux. Higher inlet air temperature produced higher combustion efficiencies, apparently the result of enhanced combustion of the larger boron particles those burn in a diffusion controlled regime. Short grains which considered primarily of the recirculation region produced larger particles and lower combustion efficiencies. The result of the normalized combustion efficiency increased with inlet air temperatures coincident with the result of the Brayton cycle thermal and the total efficiency relating to the heat input.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.1
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• pp.26-33
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• 2003

Recess is a geometrical configuration shape that the exit surface of an inner injector is located at a certain length inward from that of an outer injector. It is known to have the characteristics that it can augment mixing efficiency and flame stabilization through internal mixing of propellant in it. So, various experiments, such as backlit stroboscopic photography, phase Doppler particle analyzer(PDPA) and mechanical patternator, were performed at several recess lengths to grasp its effect on the spray characteristics of spray angle, breakup length, atomization and' mixing. Recess length was normalized to dimensionless recess number and two principal mechanisms of impingement and swirl recovery were introduced to explain its influence on the spray characteristics. The effect of recess on SMD doesn't appear significantly near the recess number where mixing efficiency attains to the maximum, whereas mass distribution and mixing efficiency are changed considerably. Thus, it can be inferred that a certain optimum recess number exists, where mixing efficiency becomes the maximum.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.7
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• pp.89-96
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• 2021

In this study, a mini hydro cyclone was designed and manufactured to achieve an inlet flow rate of 2 L/min in the experiment, which was conducted using alumina powder with a specific gravity of 3.97. This hydro cyclone was studied for using in steam and water analysis system (SWAS) of thermal power plant and was manufactured by 3D printing. Numerical analysis was performed with Solidworks Flow Simulation, utilizing the reynolds stress method (RSM) of fluid multiphase flow analysis models. Experimental and numerical analysis were performed under the three conditions of inlet velocity 2.0, 4.0, and 6.0 m/s. The separation efficiency was over 80% at all inlet velocity conditions. At the inlet velocity 4m/s, the separation efficiency was the best, and it was confirmed that the efficiency was more than 90%.

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1541-1544
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• 2002

The concentration of B in steels is important due to its influence on mechanical properties of steel such as hardenability, hot workability, and creep resistance. An analytical method has been developed to determine B in steel samples by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). National Institute of Standard and Technology Standard Reference Material (NIST SRM) 348a was analyzed to validate the analytical method. The steel sample was digested in a centrifuge bottle with addition of aqua regia and $^{10}B$ spike isotope. Sample pH was then adjusted to higher than 10 to precipitate most matrix elements such as Fe, Cr, and Ni. After centrifugation, the supernatant solution was passed through a cation exchange column to enhance the matrix separation efficiency. B recovery efficiency was about 37%, while matrix removal efficiency was higher than 99.9% for major matrix elements. The isotope dilution method was used for quantification and the determined B concentration was in good agreement with the certified value.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1206-1209
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• 2007

Both PM-OLEDs and AM-OLEDs are now in production. However, manufacturers are still concerned about life-time, voltage drift, operating voltage and efficiency in order to develop larger displays. Most material suppliers seem to be focussing on emitters and the benefits of introducing suitable charge transporters have been largely unexplored. OLED-T has developed a novel organic electron injector (Trade Name: EI-101) which evaporates at a very low temperature of $300^{\circ}C$ as opposed to the conventional LiF which requires $580^{\circ}C$. EI-101 has been found to increase the lifetime by up to 12%, reduce the voltage drift by up to 61% and increase the efficiency by up to 15%. The material can be handled in air and in situ Q-mass spectroscopy on extended thermal evaporation has confirmed its high stability for use in mass production.

• Journal of Environmental Science International
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• v.6 no.4
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• pp.391-397
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• 1997

The study was carried out to demonstrate the superiority of used packing in view of energy saving and efficiency of mass transfer, comparing with conventional packing. The results are as follows : 1. Owing to low Pressure drop under high load. 25mm NSW-ring, pp. can cause energy saving 2. The unique magnitudes of used packing are as follows $C_G$=5.78, m=0.67, n=0.46 3. Used packing can make high efficiency including energy saving because of low pres sure drop per the number of transfer unit. To rate the characteristic of packing, It should be carried out that the measurement of pressure drop per packing height and per the number of transfer unfit. This study demonstrated the superiority of used packing by carring out above experiment and could be used as basic reference for design and predicting efficiency of packing tower which is tilled with same packing.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.5
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• pp.597-603
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• 2016

In this paper a comparative thermodynamics analysis is carried out for organic Rankine cycle (ORC) and ammonia-water Rankine cycle (AWRC) utilizing low-grade heat sources. Effects of the working fluid, ammonia concentration, and turbine inlet pressure are systematically investigated on the system performance such as mass flow rate, pressure ratio, turbine-exit volume flow, and net power production as well as the thermal efficiency. Results show that ORC with a proper working fluid shows higher thermal efficiency than AWRC, however, AWRC shows lower mass flow rate of working fluid and lower pressure ratio of expander than ORC.