• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.472-475
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• 1997

It is well known that pneumatic motors convert fluid power into mechanical power with a low efficiency. The Value of the efficiency depends on several factors, of which the most important are ; type of motor, speed, supply pressure, sie and geometry of the motor. This paper presents an analytical and experimental study of the performance of he vane type pneumatic motors. This investigation deals with all the pneumatic motors. This investigation deals with all the pneumatic motors. This investigation deals with all the major aspects of the air flow through a vane type pneumatic motor and pints out which are the main causes of the low efficiency of the motor, and therefore indicates which changes in a motor design an lead to optimum performance.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.4
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• pp.374-383
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• 2011

A numerical model based on a mode method coupling beams and a rectangular plate is proposed to estimate radiation characteristics of an edge-clamped rectangular plate. The radiation efficiency and radiation power in the audio frequency range including the critical frequency can be predicted. The proposed model is rather simple and straightforward and gives reliable results comparing to the previous studies. The estimated radiation characteristics are compared to those of the pinned condition plates and also to those based on the formulae proposed by Maidanik. The radiation efficiency of the clamped plate seems a little higher than that of the pinned plate in the frequency range of corner and edge modes. It is explicitly shown that the power as well as efficiency at high frequencies is not influenced by these edge boundary conditions.

• Journal of Agricultural Extension & Community Development
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• v.23 no.4
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• pp.441-448
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• 2016

The study aims to explore the problems of analysis unit when examining management performance and efficiency using DEA (Data Envelopment Analysis). Generally the DEA results depend on input, output, and analysis units. We used data from Park (2012) which analyze paddy farmers in Jeonnam province. Results show that data from farm household unit was well fitted to examine management efficiency, not data from per area unit. This study will be helpful for researchers and practitioners to understand proper analysis unit when using the DEA for enhancing farm competitiveness.

• IE interfaces
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• v.22 no.3
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• pp.192-204
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• 2009

Based on the characteristics of 'Korean electric power industry R&D programs', this study proposes a new performance evaluation framework where electric power industry related R&D projects are scrutinized. The abovementioned R&D programs have their own goals and especially they emphasize the effectiveness as well as the efficiency of each subordinate R&D project. Hence, in this framework, a performance evaluation procedure is established and then a mathematical model is developed according to the procedure. The model calculates performance evaluation indices for a set of R&D projects integrating the effectiveness with the efficiency of each R&D project. In a case study with an empirical dataset, statistical significance is tested on the integrated performance evaluation indices of R&D projects regarding organizational types and program categories considered.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.2
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• pp.354-360
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• 2004

It is well known that pneumatic actuators convert fluid power into mechanical power with a low efficiency. The pneumatic rotary actuators are used in not only marine winches. but also hoists, agitators, and excavators. The efficiency of pneumatic rotary actuators depends on several factors, such as type of actuator. speed, supply pressure. size and geometry of the actuator. This paper presents an analytical and experimental study of the performance of pneumatic rotary actuators. We investigate all the major aspects of the air flow through a pneumatic rotary actuator and points out the main causes of the low efficiency of the actuator. Therefore the design parameters which can lead to optimum performance are obtained.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.5
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• pp.773-781
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• 2004

This research was Performed to raise grade efficiency of Sturtevant type air classifier. to treat powder less than $74\mu\textrm{m}$ particle produced at the crushing process of the dry aggregates manufacturing system or concrete wastes recycling system. The experimental conditions were in the ranges. 0.85 to 5.15 $m^3$/s of primary air flow rate. 0.005 to 0.015 $m^3$/s of secondary air flow rate $30^{\circ}$ to $70^{\circ}$ of auxiliary blades angle. respectively. for 1.7~3.3 kg/min of the powder feed rate. It was found that the grade efficiency of the air classifier was increased as the baffle plate was attached at the expansion region. and the optimal operating conditions of the air flow rates and the blade angle were obtained. The fractional recovery curves from the experiments were well agreement with the theoretical one of Molerus model.

• Agricultural and Biosystems Engineering
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• v.2 no.1
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• pp.7-14
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• 2001

A rice mill plant with a capacity of 3 t/h was constructed with automated facilities at Chonnam National University. A simulation model was developed with SLAMSYSTEM for evaluation and improving the rice mill process. The developed model was validated in the views of hulling efficiency, milling efficiency, milled rice recovery, other materials produced, at bottlenecks in the processes. The results of hulling efficiency, milling efficiency, milled rice recovery in the simulation were, respectively, 81.1%, 89,5%, and 73.1%, while those of the actual mill plant were 81.5%, 90.2%, and 73.5%. The simulation results including the rates of other materials(chaff, bran, broken rice, stone, etc) produced in the processes were almost similar with those of the actual process. In the simulation the bottlenecks were found out in the process for separating brown rice and sorting colored rice. These phenomena also appeared in the actual process. It needed to increase the hourly capacities of the brown rice separator and the rice color sorter. As the developed model could well express the automated rice mill plant, it could be used for designing and improving rice mill plants.

• Special Issue of the Society of Naval Architects of Korea
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• 2005.06a
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• pp.198-205
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• 2005

Reduction of labor hour for cleaning up of the used abrasives after blasting. is attempted by improving the efficiency of abrasive recovery process in the protective coating of ship's block, For this purpose, the theoretical background for pneumatic transport technology in the abrasive recovery system as well as experimental evaluation on the effect of design parameters such as flow pattern, saltation velocity and pressure drop on the efficiency of the abrasive recovery system are employed . By optimizing the operating parameters such as the length and diameter of the suction hose, specification of recovery device and recovery mouth, a new method which can dramatically increase the efficiency of abrasive recovery system, is proposed.

• STI Policy Review
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• v.2 no.3
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• pp.35-44
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• 2011

Korea has rapidly increased R&D investment over the last few decades and the intensity of R&D investment is among the highest in the world; however, there are serious concerns about R&D performance and R&D efficiency. This study is to improve the economic assessment methodology regarding a feasibility study for national R&D programs that are thought to be one of the most prominent ways to enhance R&D efficiency. In order to improve the methodology of economic assessment, a few of important factors such as technical or market uncertainty, spillover effect, and R&D contribution ratio should be covered in the model. The focus of this article is technological and market uncertainty that has a close relation with strategic flexibility and utilization potential to increase the value of R&D programs. To improve the current linear and definitive R&D process, a new framework with strategic flexibility is suggested, in which the result of economic assessment that considers technological and market uncertainty is reflected in planning. That kind of feedback process is expected to enhance the value of the program/project as well as R&D efficiency.

• Journal of Magnetics
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• v.21 no.1
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• pp.125-132
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• 2016

High gradient magnetic separation (HGMS) is the most commonly used magnetic cell separation technique in biomedical science. However, parameters determining target cell capture efficiencies in HGMS are still not well understood. This limitation leads to loss of information and resources. The present study develops a bead-capture theory to predict capture efficiencies in HGMS. The theory is tested with CD3- and CD14-positive cells in combination with paramagnetic beads of different sizes and a generic immunomagnetic separation system. Data depict a linear relationship between normalized capture efficiency and the bead concentration. In addition, it is shown that key biological functions of target cells are not affected for all bead sizes and concentrations used. In summary, linear bead-capture theory predicts capture efficiency ($E_t$) in a highly significant manner.