• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.702-704
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• 2001

This paper investigates efficiency and power factor of Switched Reluctance Motor (SRM) using Finite Element Method considered driving circuit. The efficiency and power factor are calculated in Input terminal and Output terminal respectively. When calculating power factor, apparent power is obtained by effective voltage and current because SRM is operated by switching of driving circuit. Efficiency is calculated by mechanical output and active power. Finally, the characteristics of efficiency and power factor in three proposed models are compared due to the switching pattern.

• Proceedings of the Safety Management and Science Conference
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• 2008.11a
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• pp.189-199
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• 2008

It is good to use DEA method as it can measure the efficiency without depending on a specific function like cost function. The method also finds out the most efficient group among the sample groups and gives us a specific number. For example, it shows what kind of factor of inefficient group gives how much input and produces how much output. Originally DEA, which was developed by Charnes, Cooper and Rhodes, allows us not only to measure the relative efficiency of Decision Making Units(DMUs) of non-profit organizations whose success cannot be measured by a single bottom-line figure such as profit but also to integrate several variables, which have different measuring scale, into a single model. Therefore we can use physical scales and financial scales simultaneously in the same model without any transformation process. In this study, price and measurable performance indexes of vehicles are used as input and outputs respectively. The purpose of this study is to propose an effective approach for evaluating the relative efficiency of vehicles and to determine the vehicles have high performance efficiency compared to product cost.

• Korean Journal of Optics and Photonics
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• v.26 no.2
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• pp.98-102
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• 2015

The radiative quantum efficiency of a solid-state laser was measured by photoacoustic spectroscopy with a PZT as the detector. The radiative quantum efficiency was about 58.3 % for a laser-diode pumped Nd:S-VAP laser under lasing conditions. The measurement of radiative quantum efficiency was presented as an effective method for the optimization of a laser resonator.

• Journal of Information Technology Services
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• v.18 no.1
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• pp.79-90
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• 2019

Maximizing energy efficiency minimizes the energy consumption of computation, storage and communications required for IT services, resulting in economic and environmental benefits. Recent advancement of flash and next generation non-volatile memory technology and price decrease of those memories have led to the rise of so-called AFA (All-Flash Array) storage devices made of flash or next generation non-volatile memory. Currently, the AFA devices are rapidly replacing traditional storages in the high-performance servers due to their fast input/output characteristics. However, it is not well known how effective the energy efficiency of the AFA devices in the real world. This paper shows input/output performance and power consumption of the AFA devices measured on the Linux XFS file system via experiments and discusses energy efficiency of the AFA devices in the real world.

• Korean Journal of Community Nutrition
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• v.12 no.2
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• pp.178-188
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• 2007

This study was performed to suggest a new efficiency measurement indicator is necessary for evaluating management efficiency of food service operations in contract-managed foodservice companies, to distinguish efficient food service providers and inefficient ones by measuring comparative efficiency among food service operations, and to provide guidance for effective management through showing benchmarking targets for improving inefficient food service providers. The subjects of this study were the 93 B&I foodservice Operations of a domestic contract food service company. The analysis was conducted using CCR model in DEA model. A software, 'Frontier analyst', was used for the analysis. Based on the results derived from comparison of efficiency evaluation classified by providers with use of DEA, it was possible to identify efficient food providers and inefficient providers, and subsequently provide benchmarking guidelines for improvement of the inefficient groups. In analyzing the differences between the results of DEA efficiency evaluation by detailed operation status of food service providers, there was significant difference of efficiency outcomes in terms of contract types, while there was no significant difference in terms of business condition.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.351-356
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• 2004

This study aims to implement an empirical research about the efficiency of container Ports, and to suggest an effective strategy which can operate container Ports more well. This paper presents a new approach to the measurement of efficiency. Data envelopment analysis(DEA), as it is called, has particular applicability in the service sector. This study applies DEA to provide an efficiency measurement for fifty three container ports including Pusan Port. As a result, we suggest several ideas that can improve the efficiency of container terminals. They are as follows. Firstly, we discriminate between efficient and inefficient container ports and then present a method that can move to efficiency container terminal and a benchmarking port. Secondly, we evaluate the efficiency of Pusan port, and grasp the position at the present time, suggest an advanced direction in future.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.3
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• pp.430-440
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• 2022

Shipping companies are key components of the logistics industry, which is extremely significant in enhancing the country's comprehensive national power and promoting global trade development. In the context of the implementation of the new development pattern strategy in China and the impact of the global novel coronavirus (COVID-19), this paper takes 22 Chinese shipping listed companies as the research object and analyses the operational efficiency of them from 2011 to 2020 based on the Super-SBM DEA Model and Window DEA Model. Factors affecting the efficiency are further analyzed with the Tobit model. The research conclude that the operational efficiency of Chinese shipping companies as a whole shows a steady increase from 2011 to 2020. Although most of them are in a relatively ef ective operation state, fewer are absolutely effective companies. Besides efficiency among companies differs obviously, which indicates the potential of further improvement and promotion. What's more, factors such as current economic development level, enterprise size, human resources quality and enterprise turnover speed have significant positive correlation to the operation efficiency of Chinese shipping listed companies, which is significant to improve the operation efficiency of Chinese shipping companies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.4
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• pp.219-223
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• 2000

The evaluation of habitability to building vibration is conducted by the values of natural frequency, amplitude displacement, damping ratio. These values can be obtained from test or analytical results. Data acquisition through test may be possible in existing building, however, to estimate the serviceability of the building, it is necessary to evaluate those values at the stage of design. The natural frequency is important and basic factor for the evaluation of the serviceability. Calculation method of the effective stiffness in RC slab is proposed. To prove the efficiency of the proposed method, sample results of the analysis and the test are compared. These results proved that the effective width proposed to calculate the effective stiffness is proper to evaluate the natural frequency.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2106-2109
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• 2008

Nanofluids have been studied as possible alternatives for heat transfer fluids to improve the efficiency of heat exchangers. There are deviations of measured effective thermal conductivities between research-groups, and the mechanisms of the effective thermal conductivity enhancement of nanofluids are not confirmed yet. In this study, the effects of particle shape on the effective thermal conductivity enhancement are discussed and presented as a possible explanation of the deviations. The particle motion effect is found to be negligible for nanofluids of high aspect ratio cylindrical particles, which is believed to be important for nanofluids of spherical particles, while the percolation network formation and contact resistance play dominant roles in determining the effective thermal conductivity.

• Geotechnical Engineering
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• v.13 no.6
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• pp.123-138
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• 1997

Electroosmotic tests were performed on saturated marine clay specimens contaminated with lead to investigate the efficiency of the electrokinetic technique for removal of heavy metals from the cohesive soils. For this purpose, testing program included variable conditions such as the concentration of lead (500, 5, 000, 50, 000mg/kg), the level of electrical current (10, 50, 100 mA), operating duration (5, 15, 30days), and the application of three dirtferent chemicals for enhancement in efficiency. The pH of inflow and outflow, electroosmotic flow and electrical conductivity during the test, and the pH and the concentration of lead across the specimen after the test are presented. Test results came to the conclusion that the electrokinetic technique was very effective to remove heavy metals such as lead from the contaminated cohesive soil. Adding ecetic acid at the cathod to dissolve the procipitates of lead hydroxide as found to be effective for the enhancement of the efficiency in remediation.