• 한국연소학회지
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• 제5권1호
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• pp.99-108
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• 2000

Regenerative burner is a product of new combustion technology for realizing higher thermal efficiency and lower emissions, moreover utilizing very high preheated air temperature up to $1,000^{\circ}C$. In this study the experimental study was carried out to find out a combustion characteristics breaking the old combustion concept. From the variation of configuration of gas nozzle and hot test on the temperature distribution and NOx, CO, it was found out that the performance of regenerative burner was better than that of existing burner, mainly due to the effect of internal gas recirculation.

• 한국자동차공학회논문집
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• 제17권3호
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• pp.142-148
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• 2009

The direct injection(DI) diesel engine has become a prime candidate for future transportation needs because of its high thermal efficiency. However, nitrogen oxides(NOx) increase in the local high temperature regions and particulate matter (PM) increases in the diffusion flame region within diesel combustion. Therefore, the demand for developing a suitable after treatment device has been increased. NOx absorbing catalysts are based on the concept of NOx storage and release making it possible to reduce NOx emission in net oxidizing gas conditions. This De-NOx system, called the LNT(Lean NOx Trap) catalyst, absorbs NOx in lean exhaust gas conditions and release it in rich conditions. This technology can give high NOx conversion efficiency, but the right amount of reducing agent should be supplied into the catalytic converter at the right time. In this research, a performance characteristics of LNT with a hydrogen enriched gas as a reductant was examined and strategies of controlling the injection and rich exhaust gas condition were studied. The NOx reduction efficiency is closely connected to the injection timing and duration of reductant. LNT can reduce NOx efficiently with only 1 % fuel penalty.

• 한국가스학회지
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• 제11권4호
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• pp.12-16
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• 2007

천연가스 자동차에 탑재되어 있는 연료압력 레귤레이터는 연료분사시스템의 압력을 일정하게 유지하는 역할을 한다. 연료압력의 정확한 제어는 천연가스 자동차가 가지고 있는 높은 효율성과 청정성을 십분 활용하기 위해서 반드시 필요한 사항이다. 본 연구에서는 천연가스 레귤레이터의 성능을 정확하게 평가할 수 있는 고압실험장치를 구축하였으며, 이 장치를 이용하여 두 가지 방식의 천연가스 레귤레이터를 평가하고 상호 비교를 하였다. 레귤레이터 밸브시스템의 설계에 따라 여러 가지 레귤레이터 성능 특성 중 동적응답과 Creep특성이 영향을 많이 받는 것으로 나타났으며, 레귤레이터 입구 압력이 높을 경우 출구 가스의 온도가 급격히 감소하는 것으로 나타남으로써 아이싱문제를 효과적으로 방지할 수 있는 방안이 마련되어야 함을 확인할 수 있었다.

• 한국생산제조학회지
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• 제20권2호
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• pp.151-156
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• 2011

This study examined the casting analysis of fuel pressure regulator of LPI vehicles. We aims to predict all the phenomenon accompanied by flow and solidification in die casting, and maximize productivity and quality through optimal casting design. As a result of comparing Types A and B of casting design, it was found that the number of overflow affected flow, flowspeed and solidification temperature. And there was a minute difference between solidification temperatures at thick section of the spare parts. Solidification began at temperatures of $624^{\circ}C{\sim}630^{\circ}C$ but after the casting was completed, temperatures at the center of the parts were $600^{\circ}C{\sim}614^{\circ}C$ Temperature of molten metal showed optimal flow at temperature of $680^{\circ}C$. It began to solidity around at $650^{\circ}C$ and to be cooled between $580^{\circ}C{\sim}550^{\circ}C$ in high speed. When the process was analysed through a computer simulation, it was found that hardness of regulators manufactured through Type B of overflow was above $H_R60$.

• 대한기계학회논문집B
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• 제30권8호
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• pp.788-795
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• 2006

From the view of the environmental protection against the use of fossil fuels, the great of efforts have been exerted to find an effective method which is not only pollutant reduction but also high thermal efficiency. Reburning is a useful technology in reducing nitric oxide through injection of a secondary hydrocarbon fuel. In this paper, an experimental study has been conducted to evaluate the hybrid effects of reburning and selective non-catalytic reaction (SNCR) on $NO_x/CO$ reduction from oxygen-enriched LPG flame. Experiments were performed in flames stabilized by a co-flow swirl burner, which was mounted at the bottom of the furnace. Tests were conducted using LPG gas as main fuel and also as reburn fuel. The paper reported data on flue gas emissions, temperature distribution in furnace and various heat fluxes at the wall for a wide range of experimental conditions. Overall temperature in the furnace, heat fluxes to the wall and $NO_x$ generation were observed to increase by oxygen-enriched combustion, but due to its hybrid effects of reburning and SNCR, $NOx/CO$ concentration in the downstream has considerably decreased.

• Tribology and Lubricants
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• 제33권1호
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• pp.23-30
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• 2017

The electric controlled marine diesel engine has fuel pump generating the high pressurized fuel for fuel injection to combustion chamber via a common rail. Fuel pump consists of a cam-roller system. Journal bearing installed between a roller and a cam-roller pin is subjected to fluctuating heavy and instant loads by cam lift. First, Kinematic analysis is carried out to predict bearing loads during one cycle acting on the journal bearing. Second, flexible multi-body dynamic analysis and transient elasto-hydrodynamic(EHD) lubrication analysis for journal bearing considering elastic deformation of cam-roller pin, roller and bearing are conducted using AVL EXCITE/PU software to predict lubrication performance. The clearance ratio and journal groove shape providing lubrication oil are important parameter in bearing design having good performance and can be changed easier than other design parameters such as diameter, width, oil supply pressure and bearing material grade. Generally, journal bearing performance is represented by the minimum oil film thickness(MOFT) and peak oil film pressure(POFP). As well as the traditional design parameters(MOFT, POFP), in this study, temperature rise of lubrication oil is also evaluated through the side leakage flow of supplied oil. By the evaluating MOFT, POFP and temperature rise, the optimum bearing clearance ratio is decided.

• Journal of Advanced Marine Engineering and Technology
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• 제34권8호
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• pp.1050-1056
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• 2010

디젤기관은 공기만을 흡입 압축한 후에 연료를 분사하여 연소하기 때문에 높은 압축비가 가능하다. 높은 압축비에 의한 고효율의 장점과 연료의 직접분사에 의한 매연미립자의 배출 및 질소산화물의 배출이 많은 단점을 갖고 있다. 이러한 문제점을 해결하기 위하여 많은 연구들이 진행되었으며 수소를 흡기중에 공급하는 기술도 연구되고 있다. 본 논문에서는 미량의 수소를 연소실에 공급하여 엔진성능에 미치는 영향을 평가하였다. 토크와 엔진속도를 100%, 75%, 50%, 25%, 0%와 700rpm, 1000rpm, 1500rpm, 2000rpm로 구분하여 실험하였다. 실험결과 질소산화물이 약간 증가하였지만 연료소비율, 스모크와 일산화탄소 배출은 감소하였다. 수소의 첨가는 저부하 영역에서는 효과가 거의 없었지만 고부하 영역에서 큰 효과가 있었다.

• 한국수소및신에너지학회논문집
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• 제31권2호
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• pp.169-176
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• 2020

There is a growing interest in hydrogen energy utilization since an alternative energy development has been demanded due to the depletion of fossil fuels. Hydrogen is produced by the reforming reaction of natural gas and biogas, and the electrolysis of water. An solid oxide electrolyte cell (SOEC) is reversible system that generates hydrogen by electrolyzing the superheated steam or producing the electricity from a fuel cell by hydrogen. If the water can be converted into steam by waste heat from other processes it is more efficient for high-temperature electrolysis to convert steam directly. The reasons are based upon the more favorable thermodynamic and electrochemical kinetic conditions for the reaction. In the present study, steam at over 180℃ and 3.4 bars generated from a boiler were converted into superheated steam at over 700℃ and 3 bars using a cylindrical steam superheater as well as the waste heat of the exhaust gas at 900℃ from a solid refuse fuel combustor. Superheated steam at over 700℃ was then supplied to a high-temperature SOEC to increase the hydrogen production efficiency of water electrolysis. Computational fluid dynamics (CFD) analysis was conducted on the effects of the number of 90° elbow connector for piping, insulation types and insulation layers of pipe on the exit temperature using a commercial Fluent simulator. For two pre-heater injection method of steam inlet and ceramic wool insulation of 100 mm thickness, the highest inlet temperature of SOEC was 744℃ at 5.9 bar.

• 에너지공학
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• 제24권4호
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• pp.140-145
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• 2015

본 연구는 경유를 2차 분사연료로 사용하는 HC-SCR 후처리장치에서 2차 분사연료의 바이오디젤 함량 변화(BD0, BD10, BD25)에 다른 NOx 변환특성을 분석하였다. 시험조건은 HC-SCR 장치의 특성, 2차 분사연료의 distillation 등을 고려하여 장치 전단온도는 $290^{\circ}C$, $320^{\circ}C$, $350^{\circ}C$로 설정하였으며, 공간속도는 55,000(1/h)으로 고정하고 연료분사량을 조절하였다. Distillation 시험결과, T90은 약 $350^{\circ}C$로 동일한 수준이었으며 바이오디젤 함량이 증가할수록 $350^{\circ}C$보다 낮은 조건에서 증발량이 감소한다는 결과를 얻었다. 2차 분사연료에 혼합된 바이오디젤 함량이 증가할수록 NOx 저감효율은 감소하는 것을 확인하였으며 저온조건($290^{\circ}C$)보다 고온조건($320^{\circ}C$, $350^{\circ}C$)에서 NOx 저감율의 차이가 더 크게 발생했다. 이러한 결과는 바이오디젤의 열악한 증발특성(Distillation)과 높은 분자량인 것으로 추측된다.

• 대한기계학회논문집
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• 제12권4호
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• pp.847-864
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• 1988

본 연구에서는 연료분출에 박리가 있는 경우와 없는 경우 각각에 대하여 화염 대 근처의 국부가속 현상이 박리에 의하여 어떻게 영향을 받는가를 실험적으로 규명하 고, 나아가서 종래에 행해져 왔던 관련 연구 결과를 재검토할려고 한다.