• 대한기계학회논문집
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• 제19권11호
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• pp.3054-3062
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• 1995

Recently, the improvement of fuel economy and the reduction of exhaust smoke and NOx have been successfully achieved by supplying diesel engines with emulsified diesel oil with water particles. In the present paper, the difference between the combustion of injected emulsified fuel and that of diesel oil spray is clarified by means of taking high-speed and color photographs of the flames in the engine cylinder. As the results, the two kinds of fuels show different combustion behavior each other in the growth of initial flame and in the termination of combustion process in the cylinder. Then, suitable combustion chamber design for the use of emulsified fuel is discussed on the basis of experimental data for various distribution of spray in different kinds of piston cavities. Some methods of clearing troubles caused by emulsified fuel injection are also discussed on the basis of performance tests with a remodeling test engine.

• 한국건설순환자원학회논문집
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• 제9권3호
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• pp.330-337
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• 2021

3D 프린팅의 기술발전으로 대형물 제작이 가능하게 되면서 이를 건축물에 적용하기 위한 연구가 활발하게 진행되고 있다. 건축물에서는 구조재와 비구조재로 구분되고 비구조재는 비정형 구조물 및 내·외장패널에 적용하기 유리하다. 3D 프린팅 재료는 기본적으로 시멘트 모르타르의 압출과 적층이 가능해야하므로 시멘트 혼화용 폴리머 와 경량재료의 사용이 필수적이다. 본 연구는 3D 프린팅 적용을 위해 시멘트 모르타르에 EVA 재유화형 분말수지를 사용하였다. 경량재료 혼입 폴리머 시멘트 모르타르의 난연특성을 평가하기 위해 골재로는 규사8호와 경량재료로 경량골재, 중공글라스를 사용하여 난연 및 불연성능을 평가하였다. 연구결과, 규사8호 및 경량골재를 사용한 시험체가 충분한 난연 및 불연성능을 보였다. EVA 재유화형 분말수지를 혼입할 경우 5% 이하로 적용하여 사용하는 것이 유리하다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1655-1657
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• 2004

The electrical fire frequently happens through carelessness of a vinyl and rubber cords such as a poor contact, a mechanical stress and so on. Electrical fire occupies the greater part(about 30%) of all fires in Korea. In this paper, we compared to the fire dispersive patterns of vinyl and rubber cords according to the external flame in the wall-model. The fire progress and dispersive patterns were measured by a high speed imaging system(HG-100K, REDLAKE, USA). From the results, short-circuit of the vinyl cords are easy to happen than the rubber cords by the external flame. The pattern of fire was progressed a flashover, scattering and disconnection. The fire progress on the vinyl cord is not observed because the ignition energy decreases. However, the fire was progressed continuously on the rubber cord.

• 한국자동차공학회논문집
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• 제6권1호
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• pp.80-89
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• 1998

The residual gas in an spark-ignition engine is one of important factors on emissions and performance such as combustion stability. With high residual gas fractions, flame speed and maximum combustion temperature are decreased and these are deeply related with combustion stability especially at idle and NOx emission at relatively high engine load. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating load. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating parameters. In the present study, the quantitative measurement technique of residual gas fraction was studied by using Fast Response Flame Ionization Detector(FRFID). The measuring technique and model for estimation of residual gas fraction were reported in this paper. By the assuming that the raw signal from FRFID saturates with the same slope for firing and misfiring cycle, in-cylinder hydrocarbon(HC) concentration can be estimated. Residual gas fraction can be obtained from the in-cylinder HC concentration measured at firing and motoring condition. The developed measurement and calibration procedure were applied to the limited engine operating and design condition such as intake manifold pressure and valve overlap. The results show relevant trends by comparing those from previous studies.

• 한국항행학회논문지
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• 제20권3호
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• pp.190-195
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• 2016

본 논문에서는 무인항공기용 소형 터보제트엔진에 대해 압축기 서지현상 및 화염소실을 방지하면서 과도응답 특성을 개선하는 제어기를 설계하였다. 터보제트 엔진의 가 감속 시 서지현상과 flame-out 현상을 방지하기 위해 연료 유량 제어 입력을 Fuzzy-PID 제어기로 생성하고 신속하고 안전하게 원하는 속도로 수렴할 수 있도록 제어기 설계한다. LabVIEW을 이용한 시뮬레이션을 통해 PID와의 응답특성 비교 분석 및 신속하고 안전하게 원하는 속도로 수렴하는 제어 성능을 확인하였다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.215-218
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• 2012

In this study, syngas laminar burning velocities with various hydrogen contents were studied using both experimental measurements and kinetic simulations. The laminar burning velocities were measured by the angle method of Bunsen flame configuration and the numerical calculations including burning velocities were made using CHEMKIN Package with USC-Mech II. A large range of syngas mixture compositions such as 10:90%, 25:75%, 50:50%, 75:25% and equivalence ratio from lean condition of 0.5 to rich condition of 5.0 have been conducted. The experimental results of burning velocity were in good agreement with previous other research data and numerical simulation. Also, it was shown that the experimental measurements of laminar burning velocity linearly increased with the increasing of $H_2$ content although the flame speed of hydrogen is faster about ten times than carbon monoxide. This phenomenon is attributed to the rapid production of the hydrogen related radicals such as H and OH at the early stage of combustion, which is confirmed the linear increasing of radical concentrations on kinetic simulation.

• Journal of Advanced Marine Engineering and Technology
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• 제34권8호
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• pp.1084-1093
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• 2010

화염 전파 특성을 나타내는 G 방정식에 기초한 Sub-grid Scale연소 모델을 이용하여 보염기 주위의 난류 예혼합 연소 해석에 관한 대 와동 모사를 수행하였다. Dynamic SGS 모델이 G방정식에 도입되었으며, 삼각형의 보염기 배면의 예혼합 연소 유동에 의해 검증되었다. 해석결과는 실험결과와의 비교를 통해 속도와 온도분포를 잘 예측하고 있음을 확인하였다.

• 한국분무공학회지
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• 제14권4호
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• pp.171-177
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• 2009

This study proposes a new stratified charge system for low emission and ultra lean burn. In order to examine combustion characteristics of the new system, sparkplug with a hole at positive pole and a common CNG injector for injecting fuel were used in this study as injector-type spark plug. The new stratified charge system injects fuel of extremely small quantities and ignites mixture around sparkplug gap. Also, the system was fitted in a visualized constant volume chamber. Then, for analysis of the combustion characteristics, we examined combustion pressure, lean inflammable limit, and visualized combustion flame according to equivalence ratio by comparison with homogeneous charge (HC) method and the new stratified charge (SC) method. As results of this study, in the case of using this system, the propagation speed of initial flame was increased and total combustion period was reduced in the ultra lean burn in the same equivalence ratio. These phenomena occurred clearly under the conditions of lean equivalence ratio. Furthermore, the lean inflammable limit of mixture was extended by using the injector-type spark plug.

• 대한화학회지
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• 제29권3호
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• pp.220-225
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• 1985

불꽃 원자 흡수 분광법의 Micro Sampling Technique을 이용하여 염의 농도가 높고, 양이 제한된 시료중에 미량으로 함유된 Cu, Zn 및 Fe의 분석을 시도하였다. 최적기간 및 분석조건을 조사한 결과 측정시간 0.3초, 시료부피 100${\mu}l$, 시료의 흡입속도 7.5ml/min, 연료와 산화기체의 혼합비 2.0 및 버어너 높이는 Cu일때 6.0mm, Zn 및 Fe는 8.0mm이었다. 이 방법을 일반적인 불꽃 방법과 비교하여 보면 시료의 전처리 과정이 필요없이 간단하고, 비교적 정밀성과 정확성이 있으며, 특히 100${\mu}l$정도로 양이 제한된 시료와 약 20% 정도로 염의 농도가 높은 시료의 경우도 버어너 틈새가 막히지 않고 안정한 불꽃에서 분석이 가능하였다.

• 한국연소학회지
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• 제16권2호
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• pp.23-32
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• 2011

To investigate cell formation in hydrocarbon/hydrogen/carbon monoxide-air premixed flames, the outward propagation and cellular instabilities were experimentally studied in a constant pressure combustion chamber at room temperature and elevated pressures. Unstretched laminar burning velocities and Markstein lengths of the mixtures were obtained by analyzing high-speed schlieren images. In this study, hydrodynamic and diffusional- thermal instabilities were evaluated to examine their effects on flame instabilities. The experimentally-measured unstretched laminar burning velocities were compared to numerical predictions using the PREMIX code. Effective Lewis numbers of premixed flames with methane addition decreased for all of the cases; meanwhile, effective Lewis numbers with propane addition increased for lean and stoichiometric conditions and increased for rich and stoichiometric cases for hydrogen-enriched flames. With the addition of propane, the propensity for cell formation significantly was diminished, whereas cellular instabilities for hydrogen-enriched flames were promoted. However, similar behavior of cellularity was obtained with the addition of methane to the reactant mixtures.