• Journal of the KSME
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• v.20 no.1
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• pp.21-30
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• 1980

기관의 흡기에 배기의 일부를 혼입하는 배기재순환 (Exhaust Gas Recirculation, 약해서 EGR)은 배기중의 NOx 농도를 저하시키는 효과가 있기 때문에 자동차용 기관의 배기정화를 위한 유효한 수단의 하나로 생각된다. 배기가스의 공해성분인 CO, HC NOx 중에서 CO, HC는 실용적인 처 리방법이 각각 여러종류 개발되어 있지만 NOx를 기관으로부터 배출한 후의 단계에서 처리하는 실용적인 방법은 매우 어렵다, 따라서 이와 같은 단계에 있어서는 EGR를 유효하게 이용하는 것이 NOx 저감대책의 지름길이라 할 수 있다. 그러나 EGR를 시행하는 경우, 신기의 흡입량은 EGR에 의하여 제한을 받아 감소하므로 신기의 감소분만큼 출력이 저하하는 것을 막을 도리는 없다. 따라서 장래 대부분의 자동차용기관이 EGR시스템을 정착하게 되면 동력성능을 저하시 키지 않기 위하여 EGR에 상당하는 실린더용적의 증가를 하거나, 어떠한 대책이 필요할 것이다. 그러므로 저자는 장래 EGR시스템을 장착하게될 경우를 고려하는 기관에 EGR을 시해하는 경우, 기관사이클, 연소 및 배기성분 운전 Paramater와 EGR의 관계등에 대하여 기술하고저 한다.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.3
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• pp.33-41
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• 1995

본 연구는 터보 과급기 부착 디젤 기관의 급가속 운전시 기관과 과급기의 과도 응답 성능을 규명하고 이를 개선하기 위한 실험을 수행하였다. 과도 응답 성능 구명은 일정한 회전 속도로 정상 운전중인 기관의 연료 펌프 랙을 10%에서 40%까지 일정 시간동안 급가속하였을 경우에 대하여 수행하였으며, 이때의 과급기 응답 지연 현상을 개선하기 위한 실험은 급가속과 동시에 압축기 출구의 흡기메니폴드 내에 일정한 압력의 공기를 추가 분사하는 방법을 이용하였다. 그리고 공기 분사 압력, 공기분사 기간, 가속률, 가속 시간 등이 압축기 출구의 압력과 온도, 터빈 입구의 압력과 온도, 실린더 압력, 기관과 과급기 회전 속도 등의 응답 성능에 미치는 영향을 가속전 정상 상태의 기관 회전 속도와 적용부하의 변화에 따라 시간의 함수로 나타내었다.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1981.05a
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• pp.4.2-4
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• 1981

The auther experienced a case of difficult decannulation in a 52-day-old male infant, in which decannulation was performed at one and half years after tracheostomy. Tracheostomy was performed for the maintenance of airway due to severe dyspnea, cyanosis, retraction of suprasternal notch and epigastrium during the inspiration with acute laryngotracheobronchitis. The patient became gradually adjusted to the continual cannula corking training along with growing process over the period of 18 months.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3315-3325
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• 1994

To study the variation of charging efficiency in the engine intake, the method to change the natural frequency of intake system using the intake control valve was studied and it has been used in actual engine to increase the intake air. In this paper, the method of characteristics was used to analyze the non-steady state and compared with the experimental data of the 6-cylinder diesel engine showing the effectiveness of the method theoretically.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2001.11a
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• pp.26-26
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• 2001

소형항공기용 IO-540 왕복엔진을 대상으로 추진기관의 성능에 미치는 배압 특성을 조사하기 위해서 지상 성능시험을 수행하였다. 본 시험은 6가지 배기조건에 대해서 엔진의 배압과 흡기압력, 토크, 그리고 프로펠러의 정지추력을 측정하였다. 엔진의 배압은 대체로 머플러를 장착할 경우와 배기관 끝단이 상대적으로 직경이 작고 길이가 길수록 증가하였다. 배압 특성은 특히 엔진의 회전속도가 고속 영역으로 갈수록 프로펠러 추력에 변화를 나타냈으며 전반적으로 추진기관 성능에 미세한 영향을 미치는 것으로 나타났다.

• Journal of Power System Engineering
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• v.10 no.1
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• pp.12-18
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• 2006

A three-degree of freedom model of intake system was contrived and investigated in various ways for the purpose of the amelioration of the volumetric efficiency in a low and transient engine speed for a multi cylinder diesel engine. The basic concept beyond this model started from the theory that each degree of freedom model has volumetric efficiency peak as many as its number of the degree of freedom. The volumetric efficiency affects significantly to the engine performance; torque characteristics, fuel economy and emission level. For commercial vehicles and stationary engines, the engine is designed so as to produce their best performance near the normal engine speeds, thus the low engine speed area has a tendency of poor volumetric efficiency. The aim of this study was highlighted on the amelioration of volumetric efficiency of low engine speed area in a multi cylinder diesel engine matched with an additional Helmholtz resonator. By the use of VIS(variable induction system) volumetric efficiency at low engine speed range was significantly improved. The availability of control by combination of VIS and CIS(conventional induction system) will be proposed as a variable induction system that would be an appropriate model for amelioration of the volumetric efficiency at low engine speed.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3311-3316
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• 2007

To analyze the influence of valve overlap period on a backfire occurrence, the single cylinder research engine with MCVVT(Mechanical Continuous Variable Valve Timing) system is developed and backfire limit equivalence ratio defined as fuel-air ratio equivalence ratio at which backfire occurs is examined according to various valve overlap period. The MCVVT is the system to control valve overlap period by mechanical device. It is estimated that the lower valve overlap period has the higher backfire limit equivalence ratio though the same energy is supplied. When the valve overlap period is changed from 30$^{circ}$ CA to 0$^{circ}$ CA, backfire limit equivalence ratio is increased 74%, approximately. It means that valve overlap period is concern in backfire occurrence, and may be one of the methods for controlling back fire occurred in a $H_2$ engine.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.4
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• pp.374-381
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• 2007

In order to verify the feasibility of expansion of back-fire limit equivalence ratio in the hydrogen-fueled engine with external mixture, the characteristics of performance and combustion are experimentally analyzed with change of intake/exhaust valve timings under the fixed valve overlap period of $0^{\circ}$ CA(non-valve overlap period). These characteristics are also tested for the change of exhaust valve closing timing while intake valve opening timing is fixed to clear the main cause of back-fire occurrence. As the results, the less valve overlap period center is retarded, the more back-fire limit equivalence ratio increases and back-fire does not occurred after TDC. In addition, it was shown that the control of back-fire is dependent on intake valve opening timing than valve overlap period.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.2
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• pp.136-141
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• 2013

In order to achieve simultaneously the ultra-low NOx, the high power and the high efficiency in a hydrogen-fueled engine with SI and the external mixture, the effects of low temperature combustion, performance and exhaust are compared and analyzed by the application of the lean boosting. As the results, the decrease rate of the high temperature in the hydrogen is less decreased than the other fuels by high constant-volume specific heat. However, when the conditions of 1.7bar and ${\Phi}=0.33$ are reached by the lean boosting, the maximum gas temperature of hydrogen is decreased under the temperature of NOx formation and it is possible to stabilize combustion below 2% of COVimep. Also, at that condition, it is feasible to achieve simultaneously NOx-free and the power of gasoline level. Therefore, it is found that the lean boosting is useful in the hydrogen-fueled engine.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.12
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• pp.1756-1762
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• 2002

To effectively meet current regulations on the exhaust emissions of diesel engine required to control the deterioration of air pollution in the whole world, this study is to investigate the effects of water induction through the air intake system on the characteristics of combustion and exhaust emissions in IDI diesel engine. A method fur supplying water through the air intake system to reduce the exhaust emissions has been considered with other methods such as water introduction in the form of water-in-fuel emulsion or water injection directly into the combustion chamber, but it has not been studied about the effects of water on the combustion concepts and the characteristics of exhaust emissions in detail until now. In this study, the formation of NOx was significantly suppressed by decreasing the gas peak temperature during the initial combustion process because the water play a role as a heat sink during evaporating in the combustion chamber, but the smoke was slightly increased by increasing water amount.