• 한국추진공학회지
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• 제10권2호
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• pp.23-30
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• 2006

수십 msec의 단시간에 큰 추력을 발생시키는 임펄스모타의 무게를 가볍게 하기 위하여 금속재와 복합재를 조합하여 수만 psia의 초고압을 지탱하는 압력용기의 설계이론을 개발하였고, 탄소성 구조해석을 통하여 이론식의 타당성을 입증하였다. 임펄스모타의 연소관을 이론식으로 설계하고 제작하여 유압시험과 지상연소시험을 실시하였다. 실험결과의 파열압력은 설계식과 구조해석 결과로 예측한 값과 유사한 값을 보였다. 본 논문의 설계이론을 통하여 설계단계에서 가볍고도 충분한 안전율을 갖는 고압용기를 간단히 설계할 수 있게 되었다.

• 한국환경과학회지
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• 제19권7호
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• pp.861-869
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• 2010

The present study aims to evaluate the characteristics of atmospheric polycyclic aromatic hydrocarbons (PAHs) pollution in roadside and residential areas of two Korean metropolitan cities (Seoul and Incheon) and a background area (Seokmolee). This purpose was established by analyzing temporal and spacial concentration distribution of total and 7 individual PAHs, which were extracted from ambient particulate matters, and by utilizing a multivariate statistical method (principal component analysis, PCA) for the qualitative determination of potential PAH sources. Target PAHs included benzo(a)anthracene (BaA), benzo(a)pyrene (BaP), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF), chrysene (Chr), dibenzo(a,h)anthracene (DahA), and indeno(1,2,3-cd)pyrene (IcdP). For all surveyed sites, the concentrations of total PAHs were higher in winter season than in other seasons. However, the concentrations of individual PAHs varied with surveyed sites. In both residential and roadside sites of Seoul and Incheon, BbF revealed the highest atmospheric levels. For all 7 target PAHs, the ambient concentrations were higher in Seoul and Incheon than in a background area (Seokmolee). In both residential and roadside areas, the concentrations of 4 target PAHs (BaA, BbF, BkF, DahA) were higher in Incheon than in Seoul. However, both the residential and roadside Chr concentrations were comparable in Seoul and Incheon. In addition, the residential IcdP concentrations were higher in Incheon than in Seoul, whereas the roadside concentrations were higher in Seoul. The roadside and residential BaP concentrations exhibited the reverse result to the IcdP concentrations. An PCA analysis suggested that atmospheric PAHs in both residential and roadside areas would be due to combined effects of several potential sources such as gasoline- and diesel-fueled vehicles, coal/oil combustion, and waste incineration.

• 한국유체기계학회 논문집
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• 제13권1호
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• pp.9-16
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• 2010

In the power generation industry, various efforts are needed to cope with tightening regulation on carbon dioxide emission. Integrated gasification combined cycle (IGCC) is a relatively environmentally friendly power generation method using coal. Moreover, pre-combustion $CO_2$ capture is possible in the IGCC system. Therefore, much effort is being made to develop advanced IGCC systems. However, removal of $CO_2$ prior to the gas turbine may affect the system performance and operation because the fuel flow, which is supplied to the gas turbine, is reduced in comparison with normal IGCC plants. This study predicts, through a parametric analysis, system performances of both an IGCC plant using normal syngas and a plant with $CO_2$ capture. Performance characteristics are compared and influence of $CO_2$ capture is discussed. By removing $CO_2$ from the syngas, the heating value of the fuel increases, and thus the required fuel flow to the gas turbine is reduced. The resulting reduction in turbine flow lowers the compressor pressure ratio, which alleviates the compressor surge problem. The performance of the bottoming cycle is not influenced much.

• 한국해양공학회지
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• 제22권3호
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• pp.82-88
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• 2008

The diesel engine of the merchant ship has been aperated in severe environments more and more, because the temperature of the exhaust gas of a combustion chamber is getting higher and higher with increasing use of heavy oil of law quality, due to the significant increase in the price of oil in recent some years. As a result, the degree of wear and corrosion between exhaust valve and seat ring is more serious compared to other engine parts. Thus the repair welding of exhaust valve and seat ring is a unique method to prolong the life of the exhaust valve, from an economical point of view. In this study, the corrosion property of both weld metal and base metal was investigated using electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram, and polarization resistance in 5% H2SO4 solution. The test specimen was a part of an exhaust valve stem being welded as the base metal, using various welding methods. In all cases, the corrosion resistance as well as hardness of the weld metal zone was superior to the base metal. In particular, plasma welding showed relatively good properties for both corrosion resistance and hardness, compared to other welding methods. In the case of DC SMAW (Shielded metal arc welding), corrosion resistance of the weld metal zone was better than that of the base metal, although its hardness was almost same as the base metal.

• 한국수소및신에너지학회논문집
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• 제23권3호
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• pp.285-292
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• 2012

The integrated gasification combined cycle (IGCC) system is well known for its high efficiency compared with that of other coal fueled power generation system. IGCC offers substantial advantages over pulverized coal combustion when carbon capture and storage (CCS) is required. Commercial plants employ different types of quenching system to meet the purpose of the system. Depending on that, the downstream units of IGCC can be modeled using different operating conditions and units. In case with $CO_2$ separation and capture, the gasifier product must be converted to hydrogen-rich syngas using Water Gas Shift (WGS) reaction. In most WGS processes, the water gas shift reactor is the biggest and heaviest component because the reaction is relatively slow compared to the other reactions and is inhibited at higher temperatures by thermodynamics. In this study, tehchno-econimic assessments were found according to the quench types and operating conditions in the WGS system. These results can improve the efficiency and reduce the cost of coal gasification.

• 한국건축시공학회지
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• 제20권1호
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• pp.27-34
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• 2020

건설 산업에서 시멘트 제조 시 발생하는 탄산가스로 인해 순환자원의 재활용 연구가 활발히 진행되고 있는 추세이다. 산업부산물 중 순환유동층 연소방식의 로내 탈황과정에서 생성되는 고칼슘 플라이애시의 경우 CaO 및 CaSO₄의 비율이 높다. 이를 고려하여 본 연구에서는 고로슬래그 미분말에 자극제로서 고칼슘 플라이애시를 혼입 하여 시멘트 대체제로 이용하고자 하였다. 그 결과, HCFA의 치환비율은 15% 이하로 하는 것이 적정할 것이라 판단되며, OPC 보다는 내구성 및 강도가 상대적으로 낮게 도출되었으나 친환경 건축 재료로서 충분히 활용 가능할 것으로 사료된다.

• 청정기술
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• 제20권4호
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• pp.359-366
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• 2014

연소전 $CO_2$ 흡수제인 PKM1-SU와 원유의 접촉분해 촉매인 FCC (fluid catalytic cracking)입자의 고온, 고압 조건 마모 실험을 수행하였다. 지름 15.1 cm, 높이 120 cm에 스파저 튜브(sparger tube, 1 mm 오리피스)를 장착한 원통형 기포유동층반응기를 이용하여, 다양한 온도조건($0{\sim}400^{\circ}C$), 압력조건(0~20 bar)에서 입자마모 실험을 수행하였다. BET, 광학현미경, 입도분석기 등을 이용하여 실험 전, 후 입자를 분석 하였다. 또한 기존의 마모도 측정 방법인 ASTM D5757-95방법을 이용하여 층물질의 높이(4.4~10.2 cm) 및 수분 주입이 입자 마모에 미치는 영향에 대하여 확인하였다.

• 설비공학논문집
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• 제19권3호
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• pp.235-244
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• 2007

In the case of the fire outburst within a partitioned space, it can disappear inside it through smoldering process if the fire cannot obtain sufficient imflammability. On the contrary, if it obtains it, the fire is not restricted within the room, spreading to the higher levels beyond outside windows and the compartment room. The method to prevent the fire spread through windows is considered to build a balcony or equip with sprinkler facilities. This case study is to identify which effects and controlibility a balcony brings about on the spread of fire through a full scale model experiment. In order to understand the effects of fire spread on the upper levels of the room on fire by changing the length of balcony, the temperature was measured, radiant heat was investigated, and products of combustion were analyzed. The result showed that when fire occured, longer length of the balcony, which linked to the outside wall of the apartments, led to the blocking of the fire spread, lower level of radiant heat, and significantly less transfer of toxic gases, and the driving force of the outburst of flame was identified as the attractive force due to the turbulence of uncombusted gases, which exist on the upper level of the outbursting flame.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.734-741
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• 2004

Boundary layer ingestion in airframe-integrated scramjet engines causes engine stall (“engine un start” hereafter) and restricts engine performance. To improve the unstart characteristics in engines, boundary layer bleed and a two-staged injection of fuel were examined in Mach 4 and Mach 6 engine tests. A boundary layer bleed system consisting of a porous plate, an air coolers, a metering orifice and an ON/OFF valve, was designed for each of the engines. First, a method to determine bleed rate requirements was developed. Porous plates were designed to suck air out of the Mach 4 engine at a rate of 200 g/s and out of the Mach 6 engine at a rate of 30 g/s. Air coolers were then optimized based on the bleed airflow rates. The exhaust air temperature could be cooled below 600 K in the porous plates and the compact air coolers. The Mach 4 engine tests showed that a small bleed rate of 3% doubled the engine operating range and thrust. With the assistance of two-staged fuel injection of H2, the engine operating range was extended to Ф0.95 and the maximum thrust was tripled to 2560 N. The Mach 6 tests showed that a bleed of 30 g/s (0.6% of captured air in the engine) extended the start limit from Ф0.48 to Ф1 to deliver a maximum thrust of 2460 N.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.1135-1139
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• 2017

화염 내 화학종의 공간적 분포는 화염의 구조 및 연소 특성을 이해하는데 중요한 지표가 되며, 그 계측을 위해 발광분광법 (Optical emission spectroscopy)은 간단하고 비침투적인 진단 방식으로 인해 널리 활용되고 있다. 본 연구에서는 측정 line-of-sight 방향의 공간 분해 계측 목적으로 개발된 발광분광기를 이용한 로켓 플룸 내 화학종 (OH radical) 분포 계측의 가능성을 제시하였다. 발광분광기의 측정 신호로부터 바닥 상태의 화학종 농도를 예측하기 위해 화염 내 열적 여기와 화학적 여기 기작을 고려하였으며, 열적으로 여기된 종에 대해서 열적 평형 상태를 가정하였다. 또한 발광분광기의 공간 분해 성능 및 공간에 따른 수광 특성을 보정하기 위한 방법론을 제시하였다.