• Journal of Advanced Marine Engineering and Technology
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• 제33권8호
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• pp.1152-1161
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• 2009

신조선 선박에서 시운전 중 주 추진 시스템의 동력을 측정하는 방법은 스트레인 게이지를 이용하여 축의 변형률로부터 얻어지는 직접적인 방법과 기계적인 또는 전기적인 픽업을 이용하여 계측한 실린더연소압력으로부터 환산된 면적에 의한 간접적인 방법으로 구분할 수 있다. 이러한 동력은 장주기로 선박의 여러 가지 해상 운동에 의해서 그리고 단주기로는 축계의 비틀림, 축계 배치 및 횡진동의 영향에 의해서 변동한다. 본 논문에서는 축동력측정과 평가를 위하여 통계적인 해석법을 소개하고 있고, 저속2행정디젤엔진과 감속기를 포함 중속 4행정 디젤엔진 모델에 의해서 이들이 확인되고 있다.

• 대한기계학회논문집B
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• 제34권4호
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• pp.443-448
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• 2010

가스발생기 사이클 액체로켓엔진에서 추진제의 공급압력 변화에 대한 성능 즉, 연소압, 터빈 파워, 엔진 혼합비, 가스발생기 연소가스의 온도 변화를 제시하였다. 로켓엔진의 주요 13개 시스템 레벨 변수를 이용하여 엔진 성능을 수치적으로 계산한다. 산화제 공급압이 증가하면 연소압과 터빈 파워는 증가하며 연료 공급압이 증가하면 연소압과 터빈 파워가 감소한다. 연료 유량 증가에 따라 감소된 가스 발생기의 혼합비는 연소가스 온도를 감소시키며 터빈 구동매질로서의 연소가스 물성을 저하시킨다. 연료 유량 증가에 따라 감소된 터빈 파워는 엔진 추력에 직접 영향을 미치는 주연소기의 연소압을 감소 시킨다.

• 한국가스학회지
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• 제14권1호
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• pp.15-20
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• 2010

최근 들어 유럽 및 미국을 중심으로 각광받고 있는 가스화 열병합 설비는 석탄이나 바이오매스, 폐기물로부터 지역의 전기 및 냉난방 에너지를 공급하는 중소형 규모의 에너지 시스템으로서 시장적 측면이나 기술적 측면에서 그 활용 가능성이 매우 밝은 것으로 예견되고 있다. 가스화로부터 얻어지는 합성가스는 일반적으로 가스엔진, 스털링 엔진, 마이크로 가스터빈 및 중소형 가스터빈 등이 원동기 연료로 사용될 수 있다. 그러나 가스화를 통한 합성가스는 일반적으로 LPG, CNG와 같은 고발열량 가스연료에 비해 발열량이 낮고, 반응성 및 화염속도도 매우 큰 차이를 보인다. 본 연구는 저발열량의 합성가스연료를 이용한 고효율 전소엔진 개발의 전 단계로서 60kW급 디젤혼소엔진을 개발하였다. 저발열량의 합성가스를 모사하기 위해 CNG에 질소를 희석한 연료를 사용하였으며, 디젤 연료 분사를 제어하기 위한 인젝터 드라이버 및 ECU를 적용하였다.

• 한국수소및신에너지학회논문집
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• 제22권3호
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• pp.386-401
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• 2011

Mathematical models for various steps in coal gasification reactions were developed and applied to investigate the effects of operation parameters on dynamic behavior of gasification process. Chemical reactions considered in these models were pyrolysis, volatile combustion, water shift reaction, steam-methane reformation, and char gasification. Kinetics of heterogeneous reactions between char and gaseous agents was based on Random pore model. Momentum balance and Stokes' law were used to estimate the residence time of solid particles (char) in an up-flow reactor. The effects of operation parameters on syngas composition, reaction temperature, carbon conversion were verified. Parameters considered here for this purpose were $O_2$-to-coal mass ratio, pressure of reactor, composition of coal, diameter of char particle. On the basis of these parametric studies some quantitative parameter-response relationships were established from both dynamic and steady-state point of view. Without depending on steady state approximation, the present model can describe both transient and long-time limit behavior of the gasification system and accordingly serve as a proto-type dynamic simulator of coal gasification process. Incorporation of heat transfer through heterogenous boundaries, slag formation and steam generation is under progress and additional refinement of mathematical models to reflect the actual design of commercial gasifiers will be made in the near futureK.

• 환경영향평가
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• 제14권4호
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• pp.227-235
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• 2005

Source contribution for VOCs collected in Seoul metropolitan area was conducted using PAMs (Photochemical assessment monitoring system) data and CMB(Chemical Mass Balance) model8.0, in order to estimate spatial and temporal variations of VOCs source contribution in that area, and also to compare with corresponding emission inventory. VOCs data used in model calculation were collected at 6 different sites of PAMs(Seokmori, Guwoldong, Simgokdong, Bulgwangdong, Jeongdong and Yangpyeong) and 22 out of 56 VOCs species were analyzed from June 2002 to march 2003 and used for CMB model estimation. The result showed that vehicle exhaust, coating and energy combustion were important sources of VOCs in Seoul metropolitan area, averaging 32.6%, 25.5% and 25.1%, respectively. In this study as well as other references, it was revealed that vehicle exhaust is the main contributor of urban area VOCs, but there is remarkable contrast between emission inventory and model estimation. Vehicle exhaust portion is seriously underestimated while coating is usually overestimated in emission estimates, compared to CMB results. Therefore, it is considered to assert and confirm the uncertainty of emission estimates and clarify the distinction between two other source apportionment methods.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2014년도 춘계학술대회 및 임시총회
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• pp.43-43
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• 2014

White rot fungi have been useful source of enzymes for the degradation of environmental pollutants including polycyclic aromatic hydrocarbons (PAHs) and synthetic dyes. PAHs are widespread organic compounds present in fossil fuels and are routinely generated by incomplete fuel combustion. PAHs are some of the major toxic pollutants of water and soil environments. Synthetic dyes are major water-pollutants, which are toxic to organisms in water environments and interfere photosynthesis of water plants. Removal of PAHs and synthetic dyes has been of interests in the environmental science especially in the environmental microbiology. Mushrooms are fungal groups that function as primary degraders of wood polyphenolic lignin. The ligninolytic enzymes produced by mushroom, including manganese peroxidase, lignin peroxidase, and laccase, mediate the oxidative degradation of lignin. The catalytic power of these enzymes in the degradation of aromatic ring compounds has been sought for the degradation of various organic compounds. In this project, we have screened 60 wild mushroom strains for their degradation activity against two representative PAHs, naphthalene and anthracene, and five aromatic dyes, including alizarin red S, crystal violet, malachite green, methylene blue, rose bengal. The degradation of PAHs was measured by GC while the decolorization of dyes was measured by both UV spectrophotometer and HPLC. As results, 9 wild mushroom strains showed high activity in degradation of PAHs and textile dyes. We also describe the secretive enzyme activities, the transcription levels, and cloning of target genes. In conjunction with this, activities of degradative enzymes, including laccase, lignin peroxidase, and Mn peroxidase, were measured in the liquid medium in the presence of PAHs and dyes. Our results showed that the laccase activity was directed correlated with the degradation, indicating that the main enzyme acts on PAHs and dyes is the laccase. The laccase activity was further simulated by the addition of $Cu^{2+}$ ion. Detailed studies of the enzyme system should be sought for future applications.

• 설비공학논문집
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• 제8권4호
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• pp.463-472
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• 1996

Experiments were carried out to study the operation characteristics of a regenerator with a thermo-syphon pump and a surface-flame burner for a lithium bromide (LiBr)-water absorption heat pump. A cylindrical-shape metal-fiber burner and commercial grade propane were used. The emission of carbon monoxide and nitric oxide was measured by a combustion gas analyzer. Ther regeneration rate of water vapor as a refrigerant was measured. It could be as a reference value showing the performance of the regenerator. The circulation rate of the LiBr-water solution was also measured from both the tanks for the weak-and the strong-solution. Using a refractometer, the LiBr concetration in the solution was calculated from the measured refractory index of the solution. Temperature of the solution and the condensed water was recorded at several points in the experimental apparatus with thermocouples, using a personal computer. This data collecting system for measuring temperature was calibrated with a set of standard thermometers. The generating rate of water vapor as refrigerant increased linearly with heat supplied. It was about 4.0g/s with the heat supplied at a rate of 16,500kcal/h. The circulation rate of LiBr solution also increases with the heat supplied. The difference in LiBr concentrations between the weak and the strong solution was in the range of 1 to 5% when the concentration of the strong solution was about 60%. It was dependent upon both the heat supplied and the circulation rate of the solution. The initial concentration and the level of the LiBr solution in the regenerator were measured and recorded before experiments. The effect of them on the generating rate of water vapor and the circulation rate of the solution was also studied. The generating rate of water vapor was not strongly dependent upon both the level of the LiBr solution and the initial LiBr concentration. However, the concentration difference of the solution increases with the initial level of the LiBr solution.

• 한국추진공학회지
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• 제8권3호
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• pp.10-16
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• 2004

원통 다발형 그레인의 연소시험 결과 저주파 불안정 현상이 나타났다. 그 원인은 원통 그레인 내면의 압력과 외면의 압력차(압력 비평형)가 주원인임을 알 수 있었으며, 그레인 반경방향으로 홀을 뚫어 그레인 내면에 상승된 압력을 외면으로 빠르게 확산되도록 하여 안정된 연소현상을 얻을 수 있었다. 그러나 고온 조건에서도 안정된 연소 현상을 얻기 위하여 직경 3mm 흘 7개를 뚫게 됨에 따라 가스발생량의 증가가 많이 둔화되어 격자를 사용하는 방법을 연구하게 되었다. 격자를 사용함으로써 큰 와류(large vorticity)를 소멸시켜 그레인에 홀을 뚫지 않고도 안정된 연소를 얻을 수 있었으며 가스 발생량도 점진적으로 증가시킬 수 있었다. 가로${\times}$세로 격자는 5${\times}$5, 그레인은 격자에 고정시키지 않을 때 가장 좋은 결과를 얻을 수 있었다.

• 한국기계가공학회지
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• 제19권9호
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• pp.116-121
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• 2020

In recent times, fuel economy enhancement and environmental regulation compliance have become the main topics of interest in the automobile industry. Electric vehicles are desirable alternatives to the existing cars that employ internal combustion engines. Specifically, electric vehicles are equipped with inverters, motors, and a gearbox instead of engines and transmission mechanisms. The gearbox is a key component, used to transmit power from the electric motor to the wheel. Therefore, the design of the gearbox is critical. However, most engineers design gears based only on their experience because no standards pertaining to the design factor exist, other than those for the gear ratios. To overcome this problem, the structural stabilities must be examined considering the design factors of the gears. In this study, we considered the module and number of teeth as the main factors. The constraints corresponded to the final gear ratio and fixed distance between each axle of the shafts. Moreover, a structural analysis was conducted, and the variation trend of the maximum equivalent stress against changes in the gear module and number of teeth was examined. By performing such an analysis, the structural stability in the design of a gear system could be effectively investigated.

• 대한기계학회논문집B
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• 제36권10호
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• pp.971-977
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• 2012

고압 인젝터의 성능은 디젤 연소엔진의 동력, 배출물, 연료소모와 직접적인 관계가 있다. 본 논문에서는 솔레노이드 코일과 피에조 세라믹으로 구동되는 커먼레일 디젤 분사용 인젝터의 응답 특성을 AMESim 코드를 사용하여 상대 비교 연구를 수행하였다. 따라서 연료압력, 분공경을 주요 해석변수로 설정하였다. 본 연구를 수행한 결과, 솔레노이드 구동 인젝터에 비해 피에조 구동 인젝터가 상대적으로 더 빠른 응답성과 더 높은 제어성을 가짐을 알 수 있었으며, 특히 다단분사 적용시, 이런 결과가 매우 효과적임을 확인할 수 있었다.