• Journal of Drive and Control
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• v.10 no.1
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• pp.7-13
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• 2013

Port size 80mm or above large-flow type solenoid valves are extensively used in dust collector and power plants. These multi-stage solenoid valve have few problem. first, multi-solenoid valves are almost depend on imports and there are weak in the brine environment and the low energy efficiency. Because these problem, increased the necessity of research on the development of large flow and high pressure type solenoid valves. In this study, describe the design method of multi-stage solenoid test bench and confirm the influence valve performance on several parameter such as diaphragm orifice diameter. At first, each part has modeled by AMESim simulation tool and combining them. This AMESim virtual multi-stage solenoid valve found influence valve performance on the valve parameter. Finally developed the multi-stage solenoid valve and verified that performance on experimental result.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.6
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• pp.114-119
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• 2004

For passenger vessels, twin shaft types in propulsion system is generally adopted to provide a high-speed performance in low draught due to restricted operating condition in harbors or water channels. Struts of twin open shaft type support the shafts, bearings, and propellers. Therefore, strut design is needed to consider not only hydrodynamic performance but also structural and noise/vibration performance, In this paper, considerations in strut design at the initial design stage have been discussed based on existing references, numerical calculations, and their comparisons. Also, the strut design of a RoPax ferry has been carried out at the initial design stage, for an example.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.5
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• pp.548-553
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• 2015

The conventional ejector-diffuser system makes use of high pressure primary stream to propel the secondary stream through pure shear action for the purposes of transport or compression of fluid. It has been widely used in many industrial applications such as seawater desalination, solar refrigeration, marine engineering, etc. The present study is performed numerically to study the performance of a two-stage ejector-diffuser system. The detailed flow phenomenon of the ejector-diffuser system has been critically predicted by means of the numerical approach using compressible Reynolds averaged Navier-Stokes (RANS) equations. The axi-symmetric supersonic ejector-diffuser flow has been solved by a fully implicit finite volume scheme with a two-equation k-omega turbulence model. The numerical results are validated with existing experimental data. Detailed flow physics and their contributions on ejector performance are detected to compare both single-stage and two-stage ejectors. The performance improvement on the ejector-diffuser system is discussed in terms of the mass flux ratio and the coefficient of power.

• Journal of the military operations research society of Korea
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• v.24 no.1
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• pp.176-188
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• 1998

In this paper, it is identified that the optimal level of each performance measures (service and inventory level) is not sensitive to an uncertain environment under JIT Kanban system designed by Moeeni. Moreover, it is proposed that the optimal design method considering multiple performance characteristics is the optimal level decision method according to the relative importance differences of each performance when there exist multiple performance characteristics. The result from the simulation analysis shows that the number of Kanban for stage 3 (final process) and stage 2 is increased at the service level. It is found that the expected loss is minimal when the cycle time decreases and the container size increases. However, the stage 1 is not affected by the number and cycle time of Kanban. It is thus important to consider carefully the cycle time and the container size of the Kanban to satisfy the demand in right time. In case of inventory level, the working inventory level decreases when the container size is decreased and the working inventory level also decreases slightly when the cycle time of the Kankban is increased in stage 1 and 2.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.556-562
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• 2007

In this paper we propose a new method which adjusts the collision resolution depending on busy status of the channel to improve performance of IEEE 802.11 DCF. This scheme reduces the number of collisions in wireless channel by decreasing the amount of movements of each station's backoff stage based on busy event count and the one stage backoff model. Through simulation, we compared the performance of our scheme with that of DCF, ADCF and SD.

• Advances in Computational Design
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• v.6 no.1
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• pp.43-53
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• 2021

Multi-stage pumps are the most popular pumps among various kinds of centrifugal pumps. Athorough review of different kinds of literature has led to the conclusion that there is a desperate need to increase the performance of the multi-stage centrifugal pump. Many investigators have put their efforts to increase the pump performance and also the work is being projected on various aspects of pump performance variables. To improve the multistage centrifugal pump performance by investigation, modification, and analysis many works of literature are available. For analysis, many researchers used the Navier-Stokes solver to create the three-dimensional unsteady turbulent flow numerical model with the standard k-ε turbulent equation. This paper mainly focuses on research related to the multi-stage centrifugal pump.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1964-1968
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• 2007

The river water heat source heat pump has the advantage in the performance compared to air source heat pump. Although its better performance, the large temperature difference between load and source makes system performance worse by nature. In this study, 2-stage compression is considered as the solution of this problem. Generally, heat pump is designed for maximum capacity rate, but it actually operates at part load condition in many cases. Therefore, an information on the part-load character is very important in view of the system overall performance. In this study, part-load performance tests of a R134a 2-stage compression heat pump were carried out over the river water and supply heating water temperature changes. The experimental results show that the system performance is influenced by the part load rates, river water temperature, load temperature, etc.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.679-680
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• 2013

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.224-229
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• 2009

A Study on the Stage Lighting Design by the Type of Performance Hall The purpose of this study is to inquire into the practice of lighting design which is changed by type of stage Proscenium Stage, Thrust Stage, Arena Stage, and Flexible Stage, which have originated from ancient Greek theatre and are still used in contemporary theatre. This studt takes a good at the practical application of lighting design to different types of stage, through which it is expected to improve the understanding of lighting as a part of performing arts and to develop the quality of stage arts. The way of lighting design by type of stage can be acstracted as the following. This is expected to be of a great help to stage arts as well as different lighting designs for each type of stage. The methodology of lighting design might have limits in its application to practice in the current war Id where theatre structures and lighting equipments are fast-developing and ever-changing. However, lighting design can develop based on the basic design concepts as the researches of all fields can develop by applying their basic theories.

• Knowledge Management Research
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• v.7 no.1
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• pp.49-63
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• 2006

The objective of the study is to verify the discriminatory power of technology innovation in predicting Early Stage Ventures' success or failure. To accomplish this objective, we test early stage ventures'(Firm's period is below 3 years)technology innovation and performance. The result of the study is expected to be useful in loan evaluation, investment decision, internal management decision making and business improvement. The results of study is as follows. First, Early Stage Ventures' technology innovation power is composed of 4 major indexes(technology, marketability, manufacturing infra and economic feasibility). Second, we find that thirty-seven minor indexes are significant ex-ante variable which are discriminating between firms' success and failure in Early Stage Ventures. Also thirty-seven minor indexes explain 57.2% of the total variance. This explainable power of these indexes is similar to that of the existing 58 index elements. Finally, we find that the most important technology innovation power of Early Stage Ventures' is economic feasibility.