• Journal of Advanced Marine Engineering and Technology
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• 제35권5호
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• pp.566-575
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• 2011

LPG 연료공급방식은 배출가스를 저감시킬 수 있는 유용한 시스템으로 연구가 지속적으로 진행되고 있다. LPG는 경유와 휘발유보다 높은 증기압과 낮은 점도와 표면장력을 유지하므로 고무류와 화학 반응에 따른 연료펌프의 기계적인 손상으로 내구성이 저하되고 있는 실정이다. 본 연구에서는 이러한 문제점을 해결하기 위해 LPLi 시스템에서 유지보수의 편리함과 가격경쟁을 위해 개발된 외장형 펌프를 사용하여 LPG 연료의 조성 및 온도에 따른 특성을 평가하고자 실험을 하였다. 그 결과로서, 내장형 펌프와 외장형 펌프의 성능차이는 거의 없으며 프로판 함유율이 높고, 연료온도가 높아짐에 따라 유량은 많아지나 펌프효율은 거의 차이가 없었다. 또한 LPG 자동차 연료공급장치의 특성상 연료조성 및 온도변화에 따른 차압도 거의 일정하게 나타내었다.

• 대한기계학회논문집B
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• 제27권11호
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• pp.1548-1562
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• 2003

This paper is the first of several companion papers which compare the methods of Air-fuel ratio determination. There are many methods which calculate Air-Fuel ratio from exhaust emission. Most of them are based on the simple chemical equations, which use balance of atom, and the error of the calculation is negligible as far as the instrumentation accuracy is guaranteed. They assume homogeneous mixture and complete combustion to the extent of oxygen availability. Because of these simple assumptions, they cannot offer the information about the fuel distribution state and the malfunction of instrument. For these limitations, Eltinge offered new one based on stricter mathematical model. This result coincides with the others very well and gives more information about the mixture state and instrumentation. Consequently this might be a general solution for Air-fuel ratio determination and exhaust composition. The objects of the calculation, however, were not commercial fuels except gasoline and the compensation method of unburned hydrocarbon was not appropriate to recent analyzer. Moreover he did not consider the fuel which contains oxygen, such as methanol, ethanol and blend of gasoline-alcohol. In this paper, Eltinge chart is expanded to the arbitrary fuel composition as the reference exhaust compositions for the purpose of further discussions about Air-fuel ratio determination methods and the charts fur gasoline, diesel, methanol, M85, liquefied petroleum gas(LPG), natural gas(NG), propane, butane are illustrated.

• 한국항공우주학회지
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• 제32권4호
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• pp.61-66
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• 2004

본 논문은 액체 로켓 엔진 연소기에 사용하는 분사기의 연소 안정성 평가를 위한 모델 시험 방법을 서술하고자 한다. 액체 로켓 엔진 연소실에서 발생하는 연소 조건을 모사하기 위해서 로켓 엔진 연소기에 적용되는 실물 크기 분사기를 이용하여, 기체상태의 산소와 메탄과 프로판의 혼합기체를 모의 추진제로 사용한 모델 연소 시험을 수행하였다. 본 모델 시험의 주요 가정은 추진제의 혼합 과정이 실제 엔진 연소기에서 발생하는 연소 불안정에 가장 큰 영향을 미치는 인자로 간주하는 것이다. 본 시험에서는 단일 F-OO-F 형태의 충돌형 분사기가 한쪽 끝이 열린 원통형 모델 연소기와 더불어 사용되었다. 기상 연소 조건에서 발생하는 동압 특성은 운전 조건에 따라 상대적인 음향 감쇠 특성을 보인다. 이러한 시험 결과를 통해 구해질 수 있는 운전 조건에 따른 음향 감쇠 특성 지도를 이용하여 여러 후보 분사기 중에 가장 안정적인 분사기를 선택할 수 있게 된다.

• 한국응용과학기술학회지
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• 제13권3호
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• pp.61-71
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• 1996

In acid-catalyzed acetal cyclization of long aliphatic aldehydes($R=n-C_7H_{15}$ ; $n-C_9H_{19}$ ; $n-C_{11}H_{23}$) with 1,1,1-tris(hydroxymethyl)propane, 2-alkyl-5-hydroxymethyl-5-ethyl-1,3-dioxanes were obtained. The final products, sodium 2-alkyl-5-(sulfonatedpropylethermethyl)-5-ethyl-1,3-propanesultion in the presence of sodium hydride. These compounds were a new group of destructible surfactants which were readily hydrolyzed and oxidized in natural water reservoirs. Physical properties of these new compounds involved some surface properties such as Krafft point(Kp), critical micelle concentration(cmc), surface tension of aqueous solutions near cmc(${\gamma}_{min}$), foaming power, emulsion power and hydrolysis properties were determined. The destructible surfactants containing 1,3-dioxane ring were synthesized to about $85{\pm}5.5%$ yield. The cmc values of the compounds by ring method were assumed to $0.5{\sim}5.0{\times}10^{-3}mol/L$ range and surface tensions at cmc were $29.5{\sim}33.0dyne/cm$ respectively at $25^{\circ}C$. The foaming power and foam stability were $170{\sim}230mm$ and $52{\sim}135mm$ respectively at $1{\times}10^{-2}mol/L$, foam was occurred rarely below $1{\times}10^{-3}mol/L$. The emulsion property of liquid paraffin was better than that of soybean oil. For hydrolysis property with ph and time, these compounds were decomposed within about 200minutes at $ph1{\sim}2$. Hopefully these compounds are expected to be a good O/W emulsifier that have decomposability in acid and may be used in the process which do not need foaming.

• 한국응용과학기술학회지
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• 제28권4호
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• pp.508-516
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• 2011

Hydrotreated biodiesel(HBD) is paraffinic bio-based liquid, with the chemical structure $C_nH_{2n+2}$, originating from vegetable oil(the process can also be applied to animal fat). The oil or fat is treated in a number of process, the most important being hydrogenation, in order to create a bio-based liquid diesel fuel. During the hydrogenation, oxygen is removed from the triglyceride and converted into water. Propane is formed as a by product and can be combusted and used for energy production. HBD can be used in conventional diesel engines, pure or blended with conventional diesel, due to its similar physical properties to diesel. This study reports the quality characteristics with chemical and physical properties as an alternative diesel fuel. Especially, HBD showed higher cetane value and number than FAME, and it is consisted of $C_{15}$ - $C_{18}$ n-paraffinic compounds. We also describes quality characteristics of HBD blends(2, 5, 10, 20, 30, 40, 50 vol%) in automotive diesel. HBD blends(max. 20 vol%) were the limit by the Korean specification due to poor low temperature characteristics.

• 한국안전학회지
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• 제33권3호
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• pp.39-45
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• 2018

The occupational safety and health act defines how to evaluate the explosion hazardous areas according to KS (Korean Industrial Standards). Current KS have to follow IEC (International Electrotechnical Commission) 60079-10-1 1st edition and there has been no change since 2008. And its 2nd edition has been revised in 2015. In this study, IEC 1st Ed. (IEC 60079-10-1 1st edition) is compared with IEC 2nd edition. Total 112 case studies including four materials (methane, propane, benzene, methanol) are selected to test and explosion hazardous ranges evaluated by IEC 1st and 2nd Ed. are analyzed according to various leakage pressures and hole sizes. In order to verify the results calculated by them, PHAST, which is one of the most representative consequence analysis programs, is employed. As a result, it can be concluded that there are many differences between IEC 1st and 2nd Ed. due to the discharge and the ventilation parameters. As comparing with PHAST, it is confirmed that IEC 1st provides more conservative values than PHAST. Even if IEC 2nd Ed. provides more conservative for gases, this fails to provide more conservative values for liquids. Therefore, it is worth to note that a large value between the explosion hazardous ranges value calculated by the IEC 1st Ed. and 2nd Ed. should be selected until further investigation and analysis is made. Morevover, the full consideration for IEC 2nd Ed. have to be needed.

• 조명전기설비학회논문지
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• 제27권8호
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• pp.83-89
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• 2013

In this paper, discharge characteristics of air in the vertical arrangement of three rods(dome-shaped, cylinder-shaped, and needle-shaped rod) and plane gap having propane flame on the plane electrode are examined under the application of a.c. and d.c. high-voltages. As the result of the experiment, flashover voltages in the presence of the flame are substantially lowered than those in the absence of flame, and relative a.c. flashover voltages in the dome-shaped, cylinder-shaped, and needle-shaped rod gaps are found 32.5%, 32.1%, and 26.4% respectively. The polarity effects with the d.c. voltages are shown, and flashover voltages in negative polarity are much lowered than those in positive one. The negative flashover voltages in the dome-shaped and cylinder-shaped gaps are found 18.3% and 18.7% respectively, but the positive ones are found 53.5% and 43.2% respectively. In the needle-shaped rod gaps, meanwhile, the flame is extinguished by corona wind, and the quenching voltages are found 28.4% under the application of a.c. voltages. The ion winds of corona and the reduction of air density are the main factors of flashover reduction owing to the flame in the case of a.c. voltages, but the electrifications of the positive ion by thermal ionization besides the above factors are remarkably found in the case of d.c. voltages.

• 한국철도학회논문집
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• 제11권1호
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• pp.7-12
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• 2008

본 연구에서는 경사각에 다른 임계속도 변화를 파악하기 위하여 축소모형 실험을 수행하였다. Froude 상사를 사용하여 1/20 축소모델 시험을 수행하였고, 화원은 메탄올, 아세톤, 헵탄을 연료로하여 Akinson과 Wu가 사용한 가스버너가 아닌 배연속도에 따라 달라지는 정사각형 풀을 사용하였으며, 터널의 각도는 $0^{\circ}$, $2^{\circ}$, $4^{\circ}$, $6^{\circ}$, $8^{\circ}$에 관하여 실험을 수행하였다. 발열량과 온도는 로드셀과 K-type 열전대를 사용하여 측정하였다. 실험결과 발열량 변화를 고려하지 않은 Atkinson과 Wu의 실험결과 보다 배연속도에 따른 발열량이 변화하는 풀화재를 사용한 경우가 더 큰 기울기 값을 얻었다. 따라서 배연속도는 화원의 연소율 변화에 직접적으로 영향을 미치기 때문에 경사터널화재 발생시 연소율의 변화에 따른 임계속도의 영향을 고려하는 것이 중요하다.

• 멤브레인
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• 제25권1호
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• pp.42-47
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• 2015

PEBAX[poly(ether-block-amide)]에 NaY zeolite를 첨가하여 PEBAX-NaY zeolite 복합막을 제조하고 제조한 복합막에 대한 $C_3H_6$와 $C_3H_8$의 투과도와 선택도($C_3H_6/C_3H_8$)에 대하여 조사하였다. SEM관찰에 의하면 PEBAX-NaY zeolite 복합막 내에 NaY zeolite는 $0.5{\sim}2.5{\mu}m$의 덩어리 상태로 분산되어 있었다. TGA측정에 의하면 PEBAX에 NaY zeolite가 첨가되면 첨가된 NaY zeolite 양만큼의 질량 변화를 알 수 있었다. 기체투과 실험에 의하면 PEBAX-NaY zeolite 복합막 내의 NaY zeolite함량이 증가할수록 $C_3H_6$와 $C_3H_8$의 투과도는 감소하였고, $C_3H_6$의 투과도는 $C_3H_8$의 투과도보다는 크게 나타났으며, 기체선택도($C_3H_6/C_3H_8$)는 감소하는 경향을 나타내었다.

• 대한화학회지
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• 제23권4호
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• pp.259-266
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• 1979

수용액상에 존재하는 2,2-비스(4-히드록시페닐)프로판, 황화비스(4-히드록시페닐) 및 비스(4-히드록시페닐)술폰의 음이온과 니트로벤젠속에 존재하는 1,6-디브르모헥산을 브롬화테트라부틸 암모늄을 상이동 촉매로 사용하여 반응시켜 새로운 폴리에테르를 합성하였다. 중합속도는 교반속도와 촉매량에 의존하였으나 어느정도 이상에서는 영향을 받지 않았다. 분배실험으로 부터 친수성 음이온이 촉매에 의하여 니트로벤젠 층으로 상이동함을 확증하였으며 일부 중합체의 본성점성도 (0.09∼0.16), 수평균분자량 (2400∼4800) 및 열안정성등을 조사하였다. 이와같은 중합 메카니즘은 소위 interfacial polymerization의 메카니즘과 다르며, 이를 구별하기 위하여 "상이동 중합''(phase transfer polymerization) 이란 용어를 사용할 것을 제안한다.