• 대한기계학회논문집B
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• 제29권5호
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• pp.554-560
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• 2005

A new method to improve the efficiency of a hydrogen fuel cell system was introduced by using variable sonic/supersonic ejectors. To obtain the variable area ratio of the nozzle throat to ejector throat which controls the mass flow rate of the suction flow, the ejectors used a movable cylinder inserted into a conventional ejector-diffuser system. Experiments were carried out to understand the flow characteristics inside the variable ejector system. The secondary mass flow rates of subsonic and supersonic ejectors were examined by varying the operating pressure ratio and area ratio. The results showed that the variable sonic/supersonic ejectors could control the recirculation ratio by changing the throat area ratio, and also showed that the recirculation ratio increased fur the variable sonic ejector and decreased for the variable supersonic ejector, as the throat area ratio increases.

• Journal of Advanced Marine Engineering and Technology
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• 제18권1호
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• pp.73-80
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• 1994

The water ejector is a low pressure high flow rate volumetric pump. It utilize the energy of a low mass flow, high velocity stream to induce a large mass flow, low velocity stream. In addition, it has a very good resistances to cavitation compared to the other type of pumps, and the maintenance cost is practically nil. There has been enormous energy loss to supply the upper part water of dam which has large potential energy as mere irrigation water in domestic multipurpose dam. The new type of energy saving system which developed through the present study can economizes over 950,000 kWh per year by mixing the upper part water of dam with the waste water by the large water ejector. This paper estimates the economical efficiency of the new type of irrigation water pumping system, and further more, represents the change of performance characteristics of large water ejector, which was adapted to this system, according to the fluctuation of upper water level that seasonally changes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.752-755
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• 2003

Injection molding is the one of the most important processes for mass production of plastic parts. Usually Injection molds for mass production are constituted to multi-cavity runner system to manufacture the more parts at a time. To uniformly fill to each cavity, multi-cavity molds are designed to geometrically balanced runner system. However. in practice this is not the case. The previous studies by Beaumount at.[2] reported that filling imbalance occurred by thermal unbalance on the mold and viscosity variation of resins and so on. In this study, we conducted experiments in order to know the causes or filling imbalance for 3 plate type mold with 8 cavities. We presented a new so called 4BF mold(4plate Type Balanced Filling Mold) to improve filling balance. We conducted a experimental injection molding to verify a efficiency of the 4BF mold. In the results of the experiment, We could confirmed the possibility of the 4BF mold.

• 상하수도학회지
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• 제18권3호
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• pp.385-391
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• 2004

This paper examines the applicability of DAF-system to the domestic sewers for the effective CSOs treatment. The procedures for the experiment include mainly two steps. One is to analyse the water qualities and settling test of the CSOs and the other focuses on general characteristics of the CSOs such as the removal efficiency of pollutant, the distribution of particle size and mass balance of DAF-system. The result of this study show that the application of DAF-system is more effective and economical than the existing treatment systems because it has two removal mechanisms of sedimentation and flotation simultaneously.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.270-274
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• 1996

Until recently pre & post-processing of finite element model has been heavily relied on expensive graphic peripheral devices. But today, with the aid of inexpensive microcomputers, very effective pre & postprocessor graphics has been developed. In this study, Pre & Post processor(MASSPRE, MASSPOST) of prediction analysis of thermal stress in mass concrete structure is developed. The developed pre & post processors are raise to the efficiency in making input data for the main program and analysis of the results produced by the main program. This MASSPOST presents a stress contour graph, volume slice, time-temperature history graph, time-stress history graph, etc.

• 한국안전학회지
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• 제32권5호
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• pp.47-53
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• 2017

In this study, we propose a new control system that effectively utilizes the interaction effect of control force through the connection of stiffness member for seismic performance enhancement of two adjacent structures equipped with active tuned mass damper (ATMD). The efficiency of the proposed control system is verified by comparing with the existing independent control system through the numerical simulations of the 10th- and 12th-story buildings. From the numerical results, it is confirmed that the proposed method can show similar or better control performance even with more economical control capacity than the existing independent control system. Another advantage is that the existing system does not exhibit the adaptive control performance in emergency of failure of one control device, whereas the proposed system can achieve successful adaptive control performance by economically and efficiently utilizing the interacting control effect through the connection member.

• 한국기계가공학회지
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• 제3권3호
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• pp.32-38
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• 2004

Recently, the system of high speed milling(HSM) is widely used for reducing the operation time and maximizing efficiency of work. The most research of high speed milling system is still leaves much to be desired. Specially the research of mass pocket high speed processing with high precision is the first and probably the last. So this paper showed mass pocket processing of high precision with a duralumin and then confirmed a cause of inferior goods through the CAD/CAM pattern simulation and experimentation. And this paper showed high speed processing system reduce the rate of inferior from this optimal pattern.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.3-9
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• 2004

The machining parts must be produced within the specification of drawing and those will be able to meet function and efficiency. At that time. it is necessary not only precision machine or machining technique but also the measurement technique is very important. So. the improvement of precise measurement technique is to be joined together at once with improvement of product technique. Finally. he quality and value of the parts are decided by precision measurement. This paper aims to study on he measurement uncertainty when the machined parts are inspected with 3-dimensional coordinate measuring machine. The objectives are to remove an error of measurement and to improve quality and productivity of the mass products.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.187-192
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• 2000

The textile which is rotated in the tumbler dryer is dried by the heated air. the energy consumption for drying textile depends on various parameters. The objective of this study is to save the energy and the drying time. One of the various methods for energy saving is EGR(exhaust gas recirculation). We set the drying equipment for this study and perform the experimental study with the changes of the recirculation rate, the input power, and the air mass flow rate. We found the optimal drying conditions.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 추계학술대회
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• pp.96-98
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• 2000

Column experiments were peformed to evaluate the efficiency of surfactant flushing for remediation of non-aqueous phase liquid (NAPL) in the soil under controlled conditions. In column experiment less than 0.1 % of the original mass of tetrachloroethylene (PCE), remained in the column after 15 pore volumes of 1% sorbitan monooleate solution were passed through columns. To determine the influence of soil parameters that may affect the remediation process, column tests were repeated with different values of grain size, application rate, surfactant type, surfactant concentration, and solution viscosity (polymer mixed with surfactant). Experimental works suggest that surfactant flushing has a great potential to rapidly remove mass from NAPL in the soil.