• Journal of Biosystems Engineering
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• 제37권5호
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• pp.287-295
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• 2012

Purpose: Some of the most representative approaches are to apply next generation technologies to save energy consumption, fully automated control system to appropriately maintain environmental conditions, and autonomous assistance system to reduce labor load and ensure operator's safety. Nevertheless, improvement of upcoming method for soil cultured greenhouse has not been sufficiently achieved. Geometrical complexity of ground in protected crop cultivation might be one of the most dominant factors in design of autonomous vehicle. While there is a practical solution fairly enough to promise an accurate travelling, such as autonomous sprayer guided by rail or induction coil, for various reasons including the limitation of producer's budget, the previously developed sprayer has not been widely distributed to market. Methods: In this study, we developed an autonomous sprayer considering travelling performance on geometrical complexity of ground in soil cultured greenhouse. To maintain a stable travelling and to acquire a real time feedback, common wire with 80 mm thick and body frame and sprayer boom. To evaluate performance of the prototype, tracking performance, climbing performance and spraying boom's uniform leveling performance were individually evaluated by corresponding experimental tests. Results: The autonomous guidance system was proved to be sufficiently suitable for accurate linear traveling with RMS as lower than approximately 10 cm from designated path. Also the prototype could climb $10^{\circ}$ of ground's slope angle with 40 kg of water weight. Uniform leveling of spraying boom was successfully performed within $0.5^{\circ}$ of sprayer boom's slope. Conclusions: Considering more complex pathways and coarse ground conditions, evaluations and improvements of the prototype should be performed for promising reliability to commercialization.

• 동력기계공학회지
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• 제20권2호
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• pp.51-57
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• 2016

Non-esterified biodiesel fuel is cheaper than esterified that because of a simple manufacturing process that only consists of filtering. Applicability of this on diesel engine with electronic control system was accomplished, then optimization adopting a fractional factorial design and response surface methodology was carried out at 25% and 50% of engine load in this study. Pressure of common rail and injection timing mainly effected on responses as specific fuel oil consumption and nitrogen oxides regardless of engine load. Estimations were 310.3 g/kWh of specific fuel oil consumption and 237 ppm of nitrogen oxides at 25% load, and 233.2 g/kWh of specific fuel oil consumption and 730 ppm of nitrogen oxides at 50% load. Tests to verify these estimations were accomplished and as the results, specific fuel oil consumption was 300.4 g/kWh and NOx was 277 ppm at 25% load and 236.8 g/kWh and 573 ppm at 50% load.

• 에너지공학
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• 제16권3호
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• pp.120-127
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• 2007

본 연구의 목적은 디젤연소장의 분위기조건에 따라 다성분 혼합연료의 질량분률이 분무착화 및 연소특성에 미치는 영향을 실험적으로 고찰하는데 있다. 착화 및 연소특성은 화학발광계측법 및 직접촬영법을 이용하여 분석되었다. 실험은 광계측기를 사용하여 RCEM에서 이루어졌으며, 이소옥탄, 노말 도데칸, 노말 헥사데칸으로 혼합한 다성분연료는 커먼레일 인젝터의 전자제어에 의해 RCEM의 연소실 내로 분사된다. 실험조건은 분사압력 42, 72, 112 MPa과 분위기온도 700, 800, 900 K로 하였다. 그 결과로서 착화지연은 고세탄가성분에 의존하고, 분위기온도가 낮을 경우 저비점성분 혼합비율의 증가에 따라 휘도영역이 현저하게 낮아지며, 열발생률이 증가하면서 확산연소기간을 단축시킨다.

• 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.

• 한국자동차공학회논문집
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• 제19권6호
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• pp.140-147
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• 2011

The injection nozzle of an electro-hydraulic injector for the common rail Diesel fuel injection system is being opened and closed by movement of a injector's needle which is balanced by pressure at the nozzle seat and at the needle control chamber, at the opposite end of the needle. In this study, the slenoid actuator was considered as a prime movers in high pressure Diesel injector. Namely a solenoid-driven Diesel injector with different driving current types, as a general method driven by solenoid coil energy, has been applied with a purpose to develop the analysis model of the solenoid actuator to predict the dynamics characteristics of the hydraulic component (injector) by using the AMESim code. Aimed at simulating the hydraulic behavior of the solenoid-driven injector, the circuit model has been developed as a unified approach to mechanical modeling in this study. As this analytic results, we know the suction force and first order time lag for driving force can be endowed in solenoid-driven injector in controlling the injection rate. Also it can predict that the input current wave exerted on solenoid coil is the dominant factor which affects on the initial needle behavior of solenoid-driven injector than the hydraulic force generated by the constant injection pressure.

• 한국자동차공학회논문집
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• 제19권6호
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• pp.17-22
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• 2011

This study is to investigate the effect of the cetane number in ultra low sulfur diesel fuel on combustion characteristics and exhaust emissions at 1500 rpm and 2.6bar BMEP in low-temperature diesel combustion with 1.9L common rail direct injection diesel engine. Low-temperature diesel combustion was achieved by adopting external high EGR rate with the strategic injection control without modification of engine components. Test fuels are ultra low sulfur diesel fuel (sulfur less than 12 ppm) with two cetane numbers (CN), i.e., CN30 and CN55. For the CN30 fuel, as a start of injection (SOI) timing is retarded, the duration of an ignition delay was decreased while still longer than $20^{\circ}CA$ for all the SOI timings. In the meanwhile, the CN55 fuel showed that an ignition delay was monotonically extended as an SOI timing is retarded but much shorter than that of the CN30 fuel. The duration of combustion for both fuels was increased as an SOI timing is retarded. For the SOI timing for the minimum BSFC, the CN30 produced nearly zero PM much less than the CN55, while keeping the level of NOx and the fuel consumption similar to the CN55 fuel. However, the CN30 produced more THC and CO than the CN55 fuel, which may come from the longer ignition delay of CN30 to make fuel and air over-mixed.

• 한국자동차공학회논문집
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• 제20권2호
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• pp.123-134
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• 2012

A typical cooling system of an engine relies on a water pump that circulates the coolant through the system. The pump is typically driven by the crankshaft through a mechanical link with engine starting. In order to reduce the friction and warm-up time of an engine, the clutch-type water pump (CWP) was applied in 2.0 liter diesel vehicle. The clutch-type water pump can force cooling water to supply into an engine by the operation of an electromagnetic clutch equipped as the inner part of pump system. The onset of CWP is decided by temperature of cooling water and engine oil. And, the control logic for an optimal operation of the clutch-type water pump was developed and applied in engine and vehicle tests. In this study, the warm-up time was measured with the conventional water pump and clutch-type water pump in engine tests. And the emission and the fuel consumption were evaluated under NEDC mode in vehicle tests. Also, tests were carried out for the various temperature conditions starting the operation of CWP. From the results of the study, the application of CWP can improve the fuel consumption and $CO_2$ reduction by about 3%.

• 한국정보통신학회논문지
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• 제16권11호
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• pp.2446-2452
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• 2012

국내외의 배출가스 규제 강화에 부합하기위하여, 사용자 의도에 따른 연료 분사시기와 분사량 조절이 가능한 커먼레일 ECU를 제어할 수 있는 알고리즘 개발의 필요에 따라서 본 논문에서는 커먼레일 엔진 전용 ECU에 적용할 수 있는 노킹 판별 및 엔진 밸런스 보정이 가능한 노킹 진단 알고리즘을 구현하여 시뮬레이터로 개발하였다. 또한 운전자가 직접 차량을 진단하는 운전자 중심의 진단 서비스를 제공하고자 시뮬레이터의 결과를 OBD-II 표준에 의거하는 차량 위주의 진단기로 개발하고자 한다. 이를 위해 자동차 고장진단 신호 및 센서 출력 신호를 송수신하는 유선 시스템과 무선 시스템인 블루투스 모듈을 이용하여 실시간 통신이 제공될 수 있는 OBD-II 진단기 S/W 설계방안을 제안함으로써 차량의 연비향상 및 유해가스 저감을 통한 엔진의 효율성 향상을 실현하도록 한다.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.14-21
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• 2011

In diesel engines, accurate EGR control is important due to its effect on nitrogen oxide and particulate matter emissions. Conventional EGR control system comprises a PI feedback controller for tracking target air mass flow and a feedforward controller for fast response. Physically, the EGR flow is affected by EGR valve lift and thermodynamic properties of the EGR path, such as pressures and temperatures. However, the conventional feedforward control output is indirectly derived from engine operating conditions, such as engine rotational speed and fuel injection quantity. Accordingly, the conventional feedforward control action counteracts the feedback controller in certain operating conditions. In order to improve this disadvantage, in this study, we proposed feedforward EGR control algorithm based on a physical model of the EGR system. The proposed EGR control strategy was validated with a 3.0 liter common rail direct injection diesel engine equipped with a DC motor type EGR valve.

• 한국자동차공학회논문집
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• 제17권1호
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• pp.105-113
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• 2009

The performance of a direct-injection type diesel engine often depends on the strength of swirl or squish, shape of combustion chamber, the number of nozzle holes, etc. This is of course because the combustion in the cylinder was affected by the mixture formation process. In this paper, combustion process of biodiesel fuel was studied by employing the piston which has several grooves with inclined plane on the piston crown to generate swirl during the compression stroke in the cylinder in order to improve the atomization of high viscosity fuel such as biodiesel fuel and toroidal type piston generally used in high speed diesel engine. To take a photograph of flame, single cylinder, four stroke diesel engine was remodeled into two stroke visible engine and high speed video camera was used. The results obtained are summarized as follows; (1) In the case of toroidal piston, when biodiesel fuel was supplied to plunger type injection system which has very low injection pressure as compared with common-rail injection system, the flame propagation speed was slowed and the maximum combustion pressure became lower. These phenomena became further aggravated as the fuel viscosity gets higher. (2) In the case of swirl groove piston, early stage of combustion such as rapid ignition timing and flame propagation was activated by intensifying the air flow in the cylinder. (3) Combustion process of biodiesel fuel was improved by the reason mentioned in paragraph (2) above. Consequently, the swirl grooves would also function to improve the combustion of high viscosity fuel.