• 터널과지하공간
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• 제24권6호
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• pp.464-472
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• 2014

환기제어 시설을 설치하지 않고 모든 공간을 개방한 형태의 대단면 주방식 채굴 작업장에 설치하는 국부선풍기의 운전에 따른 기류유동형태는 재순환을 포함하고 있어 복잡하고 정량화가 어렵고 환기효율 또한 매우 낮은 편이다. 본 논문에서는 국부선풍기의 운전에 따라 하류편의 기류 운동에너지 증가 및 정압강하 현상인 벤츄리(venturi) 효과로 인접갱도로부터 기류가 유입되어 기류 유동방향으로 환기량이 증가하는 현상을 선풍기 종류 및 설치방법 별로 CFD분석하였다. 분석대상 선풍기는 축류선풍기 1종류 및 프로펠러 선풍기 2종류이며 축류선풍기 중심점 설치 위치를 1.0, 1.5, 2.0m로 변경함에 따른 벤츄리 효과의 차이를 분석하였다. 연구결과는 공기질 개선을 통한 작업환경 관리를 위한 국부 환기의 경제성 및 효율성을 제고하는데 기여할 것으로 기대된다.

• 한국유체기계학회 논문집
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• 제11권5호
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• pp.44-49
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• 2008

As the alternative energy, renewable energy should have been developing by many techniques, in order to substitute the fossil fuel which will be disappeared in the near future. One of the small hydropower generator, main concept of tubular turbine is based on using the different water pressure levels in pipe lines, energy which was initially wasted by using a reducing valve at the end of the pipeline, is collected by turbine in the hydro power generator. A propeller shaped hydro turbine has been used in order to use this renewable pressure energy in order to acquire basic design data of tubular type hydraulic turbine, output power, head, efficiency characteristics due to the guide vane opening angle are examined in detail. First, it ensures the reliance of CFD by that of compared with experiment data. After all, the results of performance characteristics of the CFD and experiment show to confirm the data that power, head and efficiency of less than 4%, 2% and 5% respectively. Moreover influences of pressure, tangential and axial velocity distributions on turbine performance are investigated.

• Ocean Systems Engineering
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• 제10권4호
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• pp.359-371
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• 2020

The performance of a multi-level overtopping wave energy converter (OWEC) has been numerically and experimentally investigated in a two-dimensional wave tank in order to study the effects of opening width of additional reservoirs. The device is a fixed OWEC consisting of an inclined ramp together with several reservoirs at different levels. A particle-based numerical simulation utilizing the Lattice Boltzmann Method (LBM) is used to simulate the flow behavior around the OWEC. Additionally, an experimental model is also built and tested in a small wave flume in order to validate the numerical results. A comparison in energy captured performance between single-level and multi-level devices has been proposed using the hydraulic efficiency. The enhancement of power capture performance is accomplished by increasing an overtopping flow rate captured by the extra reservoirs. However, a noticeably large opening of the extra reservoirs can result in a reduction in the power efficiency. The overtopping flow behavior into the reservoirs is also presented and discussed. Moreover, the results of hydrodynamic performance are compared with a similar study, of which a similar tendency is achieved. Nevertheless, the LBM simulations consume less computational time in both pre-processing and calculating phases.

• 한국자동차공학회논문집
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• 제18권1호
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• pp.93-98
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• 2010

An object of this study is to confirm the opening amount of the throttle valve that is begun the temperature separation of vortex tube for various engine speed and load condition in a common rail diesel engine. The vortex tube located at downstream of the exhaust manifold is a device separating the incoming exhaust gas to hot and cold stream. To find optimum separation efficiency of vortex tube, the opening amount of throttle valve has been investigated for various engine speed and load conditions. Engine speed was found that the influence of engine speed was dominant compared with that of engine load. As engine speed was increased, the throttle opening amount starting temperature separation was reduced.

• 한국수소및신에너지학회논문집
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• 제21권2호
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• pp.98-103
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• 2010

In order to develop two-stroke free-piston hydrogen engine to obtain high thermal efficiency and low emission, backfire occurrence have to be prevented. In this research, backfire characteristics are analyzed as functions of the intake valve opening timing and compression chamber pressure under piston by using RICEM (Rapid Intake Compression Expansion Machine) that has reverse uni-flow scavenging. As the result, reverse uni-flow scavenging is advantage about back fire. but, it exists suitable intake valve opening timing and its timing become known that equivalence ratio 1 retard until the piston rises. Also, To rise chamber pressure of lower piston, this does not cause backfire occurs in equivalent ratio 0.6 observed back fire. Therefore, 2cycle hydrogen fueled free-piston engine is undesirable scavenging compression by compressing the piston.

• 교육시설
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• 제16권1호
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• pp.59-68
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• 2009

In the knowledge-base 21st century, schools are required functions as a place of education for student as well as a place of life-long education for community. Therefore schools are needed to be open and to be multiple. The purpose of this study is to analysis of open-facilities to community of twenty elementary schools in Busan and to suggest a design guideline for open -facilities of school plan at the base of this analysis. The main contents of this study are as follows: 1) Study for general ideals and necessity of opening school facilities to community. 2) Establish the study objects of the opening facilities by existing studies and a questionnaire. 3) Focused on twenty elementary schools in Busan, analysis of the characteristics of opening facilities in terms of the using efficiency, that is, the approachability, the recognition and the territoriality. 4) At the base of 1) 2) 3), results are as follows: $\circ$ In consideration of approachability, the block plan of the open-facilities should be designed at making a circulation system without interruption of the student's educational area. $\circ$ In consideration of recognition, the form and detail of external and internal of the open-facilities should be designed at making distinction with the student's educational area. $\circ$ In consideration of territoriality, the zone of the open-facilities should be designed at composing exclusive hall, staircase and sanitation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1969-1974
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• 2004

The performance of small cyclone is analysed by an experiment for the purpose of developing a bag-less vacuum cleaner. For the high collection efficiency and low pressure loss cyclone, the effect of cyclone inlet feature must be well understood. Four types of the helical inlet are considered to compare with the normal tangential inlet, and also various inlet velocities are used to each inlet type. Based on the reference dimension, each type of inlet shows the changes of the grade efficiency and pressure loss which determine the cyclone quality. The results show that the helical inlet has the smaller cut-size but bigger pressure loss than the tangential inlet. And the degree of opening area influences factors of cyclone performance. As the inlet velocity is increased, the cut-size becomes smaller and the pressure loss becomes bigger of each cyclone. Further studies are required to understand the optimized helical inlet of cyclone.

• 설비공학논문집
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• 제27권8호
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• pp.440-447
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• 2015

In the shipbuilding process, the confined work spaces of the ship are formed continuously; the ventilation method can therefore be limited to dilution ventilation due to the complex structure and limited opening of the confined space. Also, it is difficult to evaluate air-quality using measurement and an adequate ventilation method. CFD simulation methods are typically used in analyzing ventilation efficiency in these cases. In this study, a method is suggested to analyze the air quality of the complex enclosures in shipbuilding using CFD. Especially, among the conventional indices, the ventilation efficiency scales or indices, the supply air contribution (SVE4), and the age of the air (SVE3) (fit for the confined and complex enclosure) were applied.

• 한국컴퓨터정보학회논문지
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• 제22권9호
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• pp.25-32
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• 2017

In this paper, we propose the softwareization of broadcasting system. Recently, the topic of industry is the fourth industrial revolution. The fourth industrial revolution is evolving from physical to virtualization. The Industrial Revolution is based on IT technology. Artificial Intelligence (AI), Big Data, and the Internet of Things, which are famous for Alpha Go, are based on software. Among IT, software is the main driver of industrial terrain change. The systemization of software on the basis of cloud environment is proceeding rapidly. System development through softwarization can reduce time to market lead time, hardware cost reduction and manual operation compared to existing hardware system. By developing and implementing broadcasting system such as IPTV based on cloud, lead time for opening service compared to existing hardware system can be shortened by more than 90% and investment cost can be saved by about 40%. In addition, the area of the system can be reduced by 50%. In addition, efficiency can be improved between infrastructures, shortening of trouble handling and ease of maintenance. Finally, we can improve customer experience through rapid service opening.

• 한국항만학회지
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• 제14권1호
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• pp.27-35
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• 2000

In Pusan Harbour, new port development projects are implemented such as the Extended Terminal adjacent to the Gamman Terminal, Pusan New Port, the Navy $\bigcirc$$\bigcirc$ piers, etc. which will require new marine traffic environments in the Passage I of Pusan Harbour. Specially, the turning basin of the Extended Terminal adjacent to the Gamman Terminal has been designed to overlay the Passage I of Pusan Harbour, which will interrupt the inbound traffic flow and the results will be worried to decrease the efficiency of port operation. Therefore, this paper will be aimed to evaluate the traffic congestion in the Pusan Passage I due to the opening of new ports within Pusan Harbour in 2006 and 2011 by using computer simulation based the queueing theory.