• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.101-102
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• 2014

Rising oil price and environmental problems are causing automotive industry to increase fuel efficiency. Improved fuel efficiency in gasoline engine was made possible by development of DISI gasoline engine. Since fuel is injected inside cylinder directly, in-cylinder temperature can be reduced than multi-port injection engine and this leads to increased compression ratio. However, engine performance is largely dependent on mixture formation process due to in-cylinder fuel injection. Especially for spray guided and air guided DISI gasoline engine, injection direction is important factor to mixture preparation. It is because interaction between intake flow and spray affect fuel-air mixture. Hence, in this study, mixture formation characteristics were analyzed by varying injection direction using KIVA 3V release2 code. Residual gas was considered for assuming combustion. Therefore, initial condition for in-cylinder temperature was set equal to the end state of exhaust stroke of combustion cycle. Since angle between intake air flow direction and spray direction affects fluid flow and evaporation field, mixture distribution was affected by fuel injection direction dominantly.

• 대한기계학회논문집B
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• 제37권3호
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• pp.221-228
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• 2013

분무유도식 DISI엔진의 성층연소운전조건에서 분무 및 화염특성에 대한 실험적 연구가 수행되었다. 연소가시화를 통하여 성층연소 DISI의 연소는 희박 예혼합 연소와 확산연소의 성격을 모두 가지고 있는 것으로 확인되었다. 분사시기에 따른 혼합기 형성특성이 연소의 특성을 결정하는 중요한 인자임을 관찰하였다. 분무와 혼합기 가시화를 통해 낮은 분위기압에서의 over-mixing, 높은 분위기압에서의 under-mixing이 발생하는 것을 확인하였으며 이러한 혼합기 형성과정의 결과에 따라 화염특성, 연소효율 등의 연소특성이 결정되는 것을 살펴볼 수 있었다. 또한, NOx, IMEP도 분사시기에 따른 경향성을 보였으며, 분사시기에 따른 연소상의 변화에 의한 영향임을 확인하였다.

• 대한기계학회논문집B
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• 제36권3호
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• pp.335-342
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• 2012

자동차배출가스는 이산화탄소($CO_2$)에 의한 지구온난화 및 탄화수소(HC)와 질소산화물($NO_x$)에 의한 오존 생성을 야기하는 등, 인체와 환경에 나쁜 영향을 미치기 때문에 이에 대한 관심이 증폭되고 있다. 가솔린 직접분사 (Gasoline Direct Injection; GDI)엔진은 디젤엔진과 같이 연소실내에 연료를 직접 공급하는 방식으로서 가솔린엔진의 취약점으로 지적되어 오던 높은 연료소비율 문제를 획기적으로 개선할 수 있는 기술로 평가되고 있다. 본 연구에서는 분무유도방식(Spray-guided type)의 GDI엔진을 이용하여 공기과잉률 2.0 이상의 초희박 연소를 통해 연료소비율을 개선하였다. 추가적인 연료소비율 개선 및 배출가스 저감을 위해 희박연소시 다단 분사전략과 Exhaust Gas Recirculation (EGR)을 적용하였다. 배출가스 수준과 운전성능을 평가하고 이를 배출가스 규제와 비교 검토함으로써 국내 관련기술 개발 방향 및 상용화 가능성에 대해 검토하고자 하였다.

• 한국자동차공학회논문집
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• 제20권4호
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• pp.39-45
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• 2012

Today gasoline engines for vehicular application are not only faced with stringent emission regulation but also with increasing requirements to better fuel economy, while guaranteeing power density. The spray-guided type gasoline direct injection (GDI) engine has an advantage of improved thermal efficiency and lower harmful emissions. Centrally mounted high pressure injector and adjacent spark plug allow stable lean combustion due to the flexible mixture stratification. In the present study, the performance and emissions characteristics of developed spray-guided type GDI combustion system were evaluated at various excess air ratio conditions. The specific fuel consumption and nitrogen oxides ($NO_x$) emissions were reduced due to the achievement of stable lean combustion under flammability limit. Multiple injection strategy was not helpful to improve fuel consumption while further reduction of $NO_x$ emissions was possible.

• 한국자동차공학회논문집
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• 제22권4호
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• pp.98-104
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• 2014

The technologies employing spray-guided type combustion system for ultra-lean combustion direct injection engine is focused as a promising technology for satisfying emission regulations and improving fuel economy. In the present study, control and design optimization of lean-burn LPG direct injection engine was carried out with control strategy and injection position changes. Inter-injection spark ignition strategy was applied and the effect of the strategy was assessed at relatively higher load operation condition than previous researches. In order to create richer mixture in the vicinity of spark plug electrode, relative distance between the dead-end of injector and the electrode of spark plug was changed.

• 대한치과마취과학회지
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• 제10권2호
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• pp.190-196
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• 2010

Difficult airway management including difficult intubation, difficult ventilation and difficult mask ventilation is a life threatening issue during anesthesia care. A 23-year-old woman with Treacher Collins syndrome was scheduled for distraction osteogenesis. She had hypoplasia of mandible and malar bone, bilateral deformities of auricles with partial deafness and antimongoloid slant of the palpebral fissures. A 56-year-old woman with mandibular hypoplasia due to childhood trauma was scheduled for distraction osteogenesis. She had a history of difficult intubation. We anticipated a difficult intubation and ventilation. Fiberoptic bronchoscopic guided awake intubation was selected for anesthesia induction. After intravenous injection of midazolam and remifentanil, 10% lidocaine pump spray on the pharyngolarynx with a direct laryngoscope and on the nasal canal. However fiberoptic bronchoscopic guided awake intubation was failed due to severe gag reflex. After intravenous injection of propofol and remifentanil using the target controlled infusion (TCI), mask ventilation was easily performed and, after intravenous injection of vecuronium, fiberoptic bronchoscopic guided intubation was easily performed using a wire reinforced endotracheal tube. The operation was completed successfully without any adverse events.

• 한국자동차공학회논문집
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• 제14권3호
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• pp.103-111
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• 2006

The spray behavior of direct-injection spark-ignition(DISI) engines is crucial for obtaining the required mixture distribution for optimal engine combustion. The spray characteristics of DISI engines are affected by many factors such as piston bowl shape, air flow, ambient temperature, injection pressure and fuel temperature. In this study, the effect of fuel temperature on the spray and combustion characteristics was partially investigated for the wall-guided system. The effect of fuel temperature on the fan spray characteristics was investigated in a steady flow rig embodied in a wind tunnel. The shadowgraphy and direct imaging methods were employed to visualize the spray development at different fuel temperatures. The microscopic characteristics of spray were investigated by the particle size measurements using a phase Doppler anemometry(PDA). The effect of injector temperature on the engine combustion characteristics during cold start and warming-up operating conditions was also investigated. Optical single cylinder DISI engine was used for the test, and the successive flame images captured by high speed camera, engine-out emissions and performance data have been analyzed. This could give the way of forming the stable mixture near the spark plug to achieve the stable combustion of DISI engine.

• Journal of Biosystems Engineering
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• 제24권3호
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• pp.209-216
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• 1999

A self-travelling sprayer was developed to avoid the exposure of an operator to agricultural chemicals and exhaust gas, to improve safety and to increase working efficiency during the application and transport work in the greenhouses. This system consists of self-travelling system and the control system for application and safety device. The auto-spray car is equipped with a liquid chemical tank of 80l capacity. The travelling system adopted mechanical steering system which link mechanism of front wheel is guided by guide rollers. The sprayer travels along the guiding pipe which is set on the furrow in the greenhouses. The sprayer stops automatically applying and traveling when the liquid chemical tank becomes empty or when the sprayer reach the turning point. The spray booms swings in a vertical plane. The control system of safety devices controls the automatic stop of the sprayer when there is an obstacle on the traveling path, or when the battery becomes discharged. The auto-spray car traveled smoothly and steadily along the guide pipe during traveling straightly and turning on the ground.

• 전기학회논문지
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• 제60권1호
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• pp.85-92
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• 2011

Main characteristic in railroad is the guided movement of the wheel by the track through a metal-to-metal contact, conferring to the rail vehicle a single degree of freedom. There are defects such as head check, shelling, corrugation, squats etc in surface of the rail by interface between the wheel and rail. These defects bring about reducing the life-cycle of rails and track components and increasing noises. In case of bad conditions, it is possible to happen to full-scale accident such as derailment. Recently, the track capacity has been increased for increasing speed and operation efficiency. So, maintenance and indirect cost have been increased. Currently, a coating method of rail construction is proposed by using the ceramics in Korea. Rails are used as the earth in electrical railroad systems. Currently traction return current is flowed through wheels of trains. In case of rails coated, problems are caused in the contact power between wheel and coating material of spray. In this paper, electric model is presented in the AT feeding method. In case of rails coated, electric model is presented. Also, standard resistance of the ceramic is demonstrated by contact power between wheel and coating material of spray.

• 대한기계학회논문집B
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• 제35권10호
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• pp.981-987
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• 2011

단기통 직접분사 가솔린엔진의 성층연소 조건에서 연소실험을 수행하였다. 각 분사압조건마다 실화가 발생하지 않는 성층연소가능 분사시기영역이 존재하였으며 이는 혼합기 형성과정의 분위기압에 따른 영향으로 판단하였다. 연소효율은 분사시기를 지각할수록 증가하며 32~28 CAD BTDC에서 최대값을 갖고 이후 감소하는 경향을 보였고 분사압이 높을수록 높은 연소효율이 나타났다. 이러한 연소효율의 경향은 IMEP와 다른 경향을 보였으며 그 이유는 높은 연소효율 조건에서 연소상이 진각되어 음의 일이 증가하였기 때문으로 판단된다. Smoke의 배출은 분사시기가 지각됨에 따라 증가하였으며 높은 분위기 압에서 국부적으로 농후한 영역이 증가하였기 때문으로 생각된다. NOx 배출도 분사시기를 지각함에 따라 감소하였으며 연소상의 지각으로 최대 연소실압력과 온도가 감소하였기 때문으로 생각된다.