• International Journal of Fluid Machinery and Systems
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• v.9 no.3
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• pp.205-212
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• 2016

The performance of a prototype pump converted from that of its model pump shows an increase in efficiency brought about by a decrease in friction loss. As the friction force working on impeller blades causes partial peripheral motion on the outlet flow from the impeller, the increase in the prototype's efficiency causes also a decrease in its input power. This paper discusses results of analyses on the behavior of the theoretical head or input power of a prototype pump. The equation of friction-drag coefficient for a flat plate was applied for the analysis of hydraulic loss in impeller blade passages. It was revealed that the friction-drag of a flat plate could be, to a certain degree, substituted for the friction drag of impeller blades, i.e. as a means for analyzing the relationship between a prototype pump's efficiency increase and input power decrease.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2227-2232
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• 2003

For a reasonable analysis of grade efficiency of cyclone separator, in-line measurements of particle size and particle concentration are needed. The purpose of this study is to define the correlation of measurement data and to measure grade efficiency and pressure drop. The authors adapted that the grade efficiency could be calculated directly from the counted particle numbers. The problem of collection efficiency calculation was different from counting rate of aerosol counters under the same conditions. It is important factor to use the rate of the particle counters to obtain reliable results. Therefore, the authors should use and calculate compensation factor considering sensitivity of aerosol counters, gas velocity and concentration affect higher 30% than originally measured grade efficiency. As the pressure drop and grade efficiency increase, as flow rate increase and then also pressure drop and grade efficiency increase.

• Asia-Pacific Journal of Business
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• v.12 no.2
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• pp.1-24
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• 2021

Purpose - We aim to verify whether CSM activities increase investment efficiency, and to verify whether the influence of CSM activities on investment efficiency is discriminatory depending on whether or not they belong to chaebol. Design/methodology/approach - Using 4,701 Korean firm-year observations over the 2011-2017 period, we used multiple regression analysis. CSM is measured by the evaluation score of the Korea Corporate Governance Service (KCGS). Findings - Our study confirms that CSM is a significantly positive relationship with investment efficiency. This shows that, as a result of CSM, the increased earnings quality acts as an incentive to increase investment efficiency. Next, in analysis of a dataset into two groups (a chaebol, non-chaebol), the results show that the relationship between CSM and investment efficiency differs among detailed indicator activities depending on whether or not they belong to chaebol. Research implications or Originality - It is significant that this study focused on and analyzed CSM as a determinant of investment efficiency, and examined the effects of whether or not it belongs to chaebol in the relationship between CSM and investment efficiency. Our results, which suggested that CSM can increase investment efficiency, are expected to provide important implications not only for managers but also for investors and supervisors.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.4
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• pp.187-191
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• 2004

In this work, we used the PCID simulator for simulation of solar cell and examined the effect of front-back surface recombination velocity, minority carrier diffusion length, junction depth and emitter sheet-resistance. As the effect of base thickness, the efficiency decreased by the increase in series resistance with the increase of the thickness and found decrease in efficiency by decrease of the current as the effect of the recombination. Also, as the effect of base resistivity, the efficiency increased somewhat with the decrease in resistivity, but when the resistivity exceeded certain value, the efficiency decreased as a increase in the recombination ratio. The optimum efficiency was obtained at the resistivity 0.5 $\Omega$-cm, and thickness $100\mu\textrm{m}$. We have successfully achieved 10.8% and 13.7% efficiency large area($103mm{\times}103mm$) mono-crystalline silicon solar cells without and with PECVD silicon nitride antireflection coating.

• Industry Promotion Research
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• v.8 no.4
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• pp.257-266
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• 2023

The research focuses on the provincial universities in the western region of China and investigates the research level of 12 provincial universities from 2017 to 2021, considering both static efficiency and dynamic efficiency. The static efficiency is examined using Data Envelopment Analysis (DEA), while the dynamic efficiency is analyzed using the Malmquist model. The analysis results are as follows: the scientific research efficiency of universities in the 12 western provinces is generally not high. Against the background of the "Double First-Class" construction, the overall efficiency of scientific research in universities is showing an increasing trend. The main reason for the increase in scientific research efficiency is the increase in scale efficiency in recent years. The total factor productivity (TFP) of research activities is influenced by the technology progress index and exhibits a pattern of initial increase, followed by a decline, and then an increase again. Research conclusion: Western colleges and universities should reasonably allocate resources for scientific research activities, perfect scientific research mechanisms, improve management standards, promote scientific innovation and corresponding achievements, and ultimately raise the scientific and technological level in western China.

• Korean Journal of Soil Science and Fertilizer
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• v.7 no.3
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• pp.147-154
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• 1974

Relationship among grain yield (Y) nitrogen efficiency (E) and nitrogen uptake amount (N) was investigated using the data from Korea and Japan in order to find out the way of increase nitrogen efficiency. The relationship between E and N could be grouped in various classes. In each class the equation. Y=EN=(b-aN)N, is valid where b is a theoretical maximum of E and a is the E/N at theoretial maximum yield. Present technique for high yield in the rice research seems to achieve 56.8 of nitrogen efficiency with 15.5kg of nitrogen uptake. Future target appears to be 63 of efficiency with 17kg of nitrogen uptake at which some farmers in Japan might reach already. It seems that the increase of nitrogen uptake for high yield is restricted without increase of nitrogen efficiency. The increase of efficiency and uptake amount of soil nitrogen seems essential to increase total nitrogen efficiency.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.6
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• pp.744-751
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• 2007

Wet scrubber is widely used to remove toxic gaseous contaminants in various industries such as semi-conductor industry, display manufacturing industry and so on. In this study, to optimize a packed bed scrubber as one of typical wet scrubber size while keeping its performance, four different packing materials were investigated at different air flow rates, liquid-gas ratios and pH values. Ammonia, hydrochloric acid and hydrofluoric acid were used as test gases to characterize the scrubber performance. Gas removal efficiency increased as the packing size decreased, which resulted in the increase of specific surface area. The increase of air flow rate led to the decrease of gas removal efficiency, while the increase of liquid-gas ratio led to the increase of gas removal efficiency. For the case of $NH_3$ gas, lower pH, and for the cases of HCl and HF, higher pH contributed to higher gas removal efficiency. Gas removal efficiency of a wet scrubber increased in the order of HCl < $NH_3$ < HF according to its water solubility.

• Journal of Urban Science
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• v.8 no.2
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• pp.13-18
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• 2019

Using self-made coil dielectric barrier discharge reactor, the removal efficiency of ethyl acetate under simulated experimental parameters such as initial concentration of waste gas, total flow rate, relative humidity and voltage was investigated. The results show that the degradation rate of ethyl acetate increases with the increase of output voltage. When other conditions remain unchanged, the degradation rate decreases with the increase of initial concentration of ethyl acetate; with the increase of total flow rate, the degradation rate of ethyl acetate decreases; with the increase of relative humidity, the degradation rate first increases and then decreases, and when the relative humidity is 64%, the degradation efficiency is the highest.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.6
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• pp.2697-2710
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• 2018

Owing to the development of Internet of Things (IoT), the fifth-generation (5G) wireless communication is going to foresee a substantial increase of mobile traffic demand. Energy efficiency and spectral efficiency are the challenges in a 5G network. Non-orthogonal multiple access (NOMA) is a promising technique to increase the system efficiency by adaptive power control (PC) in a 5G network. This paper proposes an efficient PC scheme based on evolutionary game theory (EGT) model for uplink power-domain NOMA system. The proposed PC scheme allows users to adaptively adjusts their transmit power level in order to improve their payoffs or throughput which results in an increase of the system efficiency. In order to separate the user signals, a successive interference cancellation (SIC) receiver installed at the base station (BS) site. The simulation results demonstrate that the proposed EGT-based PC scheme outperforms the traditional game theory-based PC schemes and orthogonal multiple access (OMA) in terms of energy efficiency and spectral efficiency.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.391-392
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• 2016

A phase shedding control algorithm to increase efficiency of 3-Phase interleaved boost converter is proposed. Conventional interleaved converter has low efficiency under the light load condition. In this paper, the number of phase is controlled in accordance with the load condition to increase the light load efficiency. The validity of proposed phase control algorithm is verified by simulation results based on measured efficiency.