• 한국추진공학회지
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• 제15권5호
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• pp.35-47
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• 2011

추력 및 혼합비 조절을 목적으로 제작된 유량조절밸브를 AMESim(4.3.0) 시뮬레이터를 통해 모델링 을 수행했다. BLDC 모터(Brushless D.C. motor)를 이용하는 유량밸브의 조절을 위하여 속도조절기법을 제안했으며, 실험을 통해 그 성능을 보였다. BLDC 모터의 속도제어 기법을 이용하는 조절밸브는 P제어 보다 시스템 활용 시 용이하고, 유량조절 실험결과를 통해 시스템에 적용 가능성을 시사했다. 플런 저 형상에 따라 유량 조절 특성을 평가했고, 두 개의 조절밸브를 이용하는 혼합비 조절의 경우 동일한 플런저 형상을 적용하는 것이 적절했다. 혼합비 조절 시 섭동 폭을 줄이기 위해 밸브 플런저의 형상을 수정한 결과 0.5%로 감소했다.

• 한국안전학회지
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• 제37권1호
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• pp.1-11
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• 2022

This numerical study investigates the effects of the size of the natural smoke vent area (10% and 1% of the floor area) and the location of the fire source (i.e., at the side and center of the stage) on the temperature distribution in the compartment and velocity distribution and mass flow rate of flow through a natural smoke vent for a reduced-scale model of a theater stage. Then, the mass flow rate of outflow through the natural smoke vent in the event of a fire for a real-scale theater stage was examined. The case with the larger natural smoke vent area and central fire source location showed lower temperature distributions and higher mass flow rates of outflow and inflow than the case with the smaller natural smoke vent area and side fire source location. The trends of the temperature distributions were closely related to those of the mass flow rates for the outflow and inflow. Additionally, the case with the larger natural smoke vent area and central fire source location exhibited the most non-uniform flow velocity distribution in all cases tested. A bidirectional flow, in which the outflow and inflow occur simultaneously, was observed through the natural smoke vent. In the event of a fire situation in a real-scale theater stage, it was predicted that the case with the larger natural smoke vent area and central fire source location would have a mass flow rate of outflow that is 43.53 times higher than that of the case with the smaller natural smoke vent area and side fire source location. The present results indicate that the natural smoke vent location should be determined by considering the location in a theater stage where a fire can occur.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.627-630
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• 2002

A methodology based on factorial design and Motto Carlo methods is developed and implemented for incorporating uncertainties within a multiphase subsurface flow and transport simulation system. Due to uncertainties in intrinsic permeability and longitudinal dispersivity, the predicted output is also uncertain based on the well-developed multiphase compositional simulator. The simulation results reveal that the uncertainties in input parameters pose considerable influences on the predicted output, and the mean and variance of permeability will have significant impacts on the modeling output. The proposed method offers an effective tool for evaluating uncertainty in multiphase flow simulation system.

• 설비공학논문집
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• 제9권2호
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• pp.180-188
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• 1997

The theoretical analysis and experiment with simulator were performed to obtain the temperature distributions in radiant heating panel and heat supply from hot water to heating space for the purpose of the development of comfortable living space from a point of view of the improvement of air quality and the enhancement of system efficiency. The relations of various parameters, such as pipe pitch, room temperature as well as flow rate and temperature of hot water and so on, with the rate of heat supplied, mean temperature and maximum temperature difference at panel surface were discussed. The effects of these parameters were also verified on the thermal performance of heating panel using the relations which could be used for the optimal design and operation of the radiant heating panel.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.344-352
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• 2006

Evacuation performance, starting transient, and plume blowback at diffuser breakdown of a straight cylindrical supersonic exhaust diffuser with no externally supplied secondary flow are investigated. Pressure records in the transitional periods are measured by a small-scale cold-gas simulator. Flow-fields evolving in the diffuser-type ejector are solved by preconditioned Favre-averaged Navier-Stokes equations with a low-Reynolds number $k-{\varepsilon}$ turbulence model edited for turbulence compressibility effects. The present RANS method is properly validated with measured static wall pressure distributions and evacuation level at steady operation as well as the pressure records during the transition regime.

• 전자공학회논문지B
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• 제31B권10호
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• pp.53-66
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• 1994

In this paper, a fuzzy expert system is developed for fault diagnoisis of a drum-type boiler system in fossil power plants. The develped fuzzy espert system is composed of knowledge base, fuzzification module, knowledge base process module, knowledge base management module, inference module, and linguistic approximation module. The main objective of the fuzzy expert system is to check the states of the system including the drum level and detect faults such as the feedwater flow sensor fault, feedwater flow control valve fault, and water wall bube rupture. The fuzzy expert system diagnoses faults using process values, manipulated values, and knowledge base which is built via interviews and questionaries with the experts on the plant operations. Finally, the validity of the developed fuzzy expert system is shown via experiments using the digital simulator for boiler system is Seoul Power Plant Unit 4.

• 대한의용생체공학회:의공학회지
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• 제20권6호
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• pp.531-537
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• 1999

본 연구에서는 FFT와 파라메트릭 방법에 의한 혈류 추정방법을 연구하고 디지털 신호처리 프로세서를 이용하여 레이저 도플러 혈률계를 구현하였다. 레이저 도플러 혈류계는 피부의 모세혈류의 흐름을 측정할수 있는 장비로서 다양한 분야에 활용이 가능하다. 구현된시스템은 TI사의 TMS320C32 DSP를 사용하였으며, 전력 스펙트럼의 모멘트값을 이용하여 혈류를 추정하였다. 혈류 추정 값은 매 0.5초마다 그래픽 사용자 인터페이스를 통해서 표시하도록 하였다. 시스템의 성능을 평가하기 위해서 혈류 시뮬레이터에 흐르는 혈류를 계단함수, 삼각함수, 사인함수로 제어하여 그 결과를 비교하였으며 인체 부위에 따른 혈류를 측정하였다. 실험결과 구현된시스템의 혈류 추정성 및 재현성이 보장되고있음을 확인할수 있었다.

• 한국자동차공학회논문집
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• 제9권4호
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• pp.10-17
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• 2001

The performance of a radiator is generally determined using a wind tunnel, in which the air velocity is uniform. However, when it is installed in a car, the distribution of the air velocity becomes nonuniform due to front-end openings, cross members, and horns etc., resulting in lower performance. In this study, several underhood flow simulations have been first performed to get flow rates and velocity distributions over the radiator. Secondly heat release rates are calculated by both a performance curve and a radiator model. Finally, using an engine cooling system simulator, radiator-top-tank temperature is predicted and the variations of heat release rate and radiator-top-tank temperature with nonuniformity of air velocity distributions are analyzed. The results show that the current engine cooling model successfully accounts for the nonuniformity effects that should be considered for higher accuracy in predicting engine cooling performance.

• 산업공학
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• 제7권3호
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• pp.171-180
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• 1994

Defined is a Multi-level Parallel Machine Flow-Shop (MPMFS) which reflects some real world manufacturing situations. Just-In-Time (JIT) philosophy is applied to the MPMFS scheduling in order to achieve lowering work-in-process inventory level as well as meeting due dates. A schedule generating simulator is developed. The latest start time of each operation is determined by a backward simulation followed by another forward simulation to analyze the schedule feasibility and actual inventory level. Reasonable schedules are available through adjusting some parameters for allowance factors such as set-up times of machines and other environmental changes. The SLAMSYSTEM under Window is employed for this processing with some input/output data handling processes devised under DOS.

• International Journal of Precision Engineering and Manufacturing
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• 제6권4호
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• pp.55-59
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• 2005

This paper presents a feasibility study whether Shida's constitutive equation being widely used for plain carbon steel in steel manufacturing industry can be extended to alloy steels with a due carbon equivalent model. T,he constitutive relation of the alloy steels (SAE9254, AISI52100 and AISI4140) is measured using hot deformation simulator (GLEEBLE 3500C) at high temperatures ($800^{\circ}C{\~}1000^{\circ}C$) within strain rates of $0.05{\~}40\;s^{-1}$. It has been found the predicted flow stress behavior (constitutive relation) of AISI52100 steel is in agreement with the measured one. On the other hand, the measured flow stress behavior of SAE9254 and AISI4140 steel partly concords with the predicted one when material experiences relatively high strain rate ($10{\~}40\;s^{-1}$) deformation at low temperature ($800^{\circ}C$). It can be deduced that, for AISI52100 steel, Shida's equation with the carbon equivalent model can be applicable directly to the roughing and intermediate finishing stand in hot rolling process for calculating the roll force and torque.