• 대한기계학회논문집B
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• 제30권6호
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• pp.553-559
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• 2006

Most diesel injector, which is currently used in high-pressure common rail fuel injection system of diesel engine, is driven by the solenoid coil energy for its needle movement. The main disadvantage of this solenoid-driven injector is a high power consumption, high power loss through solenoid coil and relatively fixed needle response's problem. In this study, a prototype piezo-driven injector, as a new injector mechanism driven by piezoelectric energy based on the concept of inverse piezo-electric effect, has been designed and fabricated to know the effect of piezo-driven injection processes on the diesel spray structure and internal nozzle flow. Firstly we investigated the spray characteristics in a constant volume chamber pressurized by nitrogen gas using the back diffusion light illumination method for high-speed temporal photography and also analyzed the inside nozzle flow by a fully transient simulation with cavitation model using VOF(volume of fraction) method. The numerical calculation has been performed to simulate the cavitating flow of 3-dimensional real size single hole nozzle along the injection duration. Results were compared between a conventional solenoid-driven injector and piezo-driven injector, both equipped with the same micro-sac multi-hole injection nozzle. The experimental results show that the piezo-driven injector has short injection delay and a faster spray development and produces higher injection velocity than the solenoid-driven injector. And the predicted simulation results with the degree of cavitation's generation inside nozzle for faster needle response In a piezo-driven injector were reflected to spray development in agreement with the experimental spray images.

• 에너지공학
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• 제24권1호
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• pp.132-136
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• 2015

바이오디젤은 재생가능한 친환경적인 연료로서 화석연료의 대체에너지로 수송분야에서 각광받고 있다. 따라서 바이오디젤의 사용량은 향후 꾸준히 증가할 것으로 보이며, 이에 대한 연구가 필요하다. 따라서 본 연구에서는 순수 디젤 대비 바이오디젤이 질량기준으로 0%, 5%, 20%, 50%, 100% 혼합된 연료를 사용하여 분무 및 연소실험을 진행하고, 분무각, 평균 입경, 열발생율 등의 특성을 도출하였다. 실험 결과, 바이오디젤의 혼합률이 증가할수록 연료의 점도 및 밀도가 증가하여 분무각과 특정 위치에서의 평균 입경이 작아지는 것을 확인할 수 있었으며, 바이오디젤의 함산소 특성으로 인해 초기 연소가 촉진되며, 이로 인해 연소 종료 시점이 앞당겨 지는 것을 볼 수 있었다.

• 한국항만경제학회지
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• 제25권4호
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• pp.131-146
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• 2009

본 논문은 부산항의 항만환경 변화에 따른 북항과 신항의 철도물동량을 분석하고자 연구를 수행하였으며 특히 신항만 건설과 신항만 배후철도 건설계획에 따라 예상되어지는 철송물동량을 예측하고자 하였다. 이를 위해 우선 부산항의 물동량 예측에 대한 국토해양부 및 KMI, KDI의 물동량 예측을 근거로 신항과 북항의 시설능력 및 예측 물동량 배분의 비중을 구하고 이를 현재 북항의 수출입 물동량의 철송물동량 비중을 근거로 신항과 북항의 철송 물동량을 예측하였다. 현재 부산항의 수출입 물동량 대비 철도운송율은 발송(수입) 10.68%, 도착(수출) 12.10%로 분석되었으며 신항과 비교적 유사한 신선대터미널의 경우에는, 수출입 물동량에 대한 철도운송 비율이 발송(수입) 12.11%, 도착(수출) 13.98%로 부산항 전체 물동량 대비 철도물동량에 비해 상대적으로 높게 나타나고 있다. 또한 KDI의 전국무역항 항만기본계획(2008)에 따르면 국내화물 운송수단별 운송분담율 중, 철도운송의 경우 2009년 기준으로 전체운송화물의 15.5%를 점유하는 것으로 예측하고 있는 바, 이를 적용한다면 부산항에서의 철도운송량은 더욱 증가할 것으로 예상된다. 아울러 신항만의 철도운송시설 건설계획과 철도운송 효율성을 제고시키면 철도운송 분담율을 더욱 제고시킬 수 있을 것으로 예측되었다. 아울러 현재까지는 구체화되지 않은 친환경을 위한 모달시프트 정책의 추진이 가시화되면 실질적인 철도물동량은 더욱 증가할 것이다. 신항만은 철송장의 건설로 해상과 철도운송 연계의 편리성이 확보되나 북측컨테이너 철송장의 경우에는 철도운영자와 철송장 운영자의 이원화로 원활한 철도운송의 장애요인으로 작용할 것으로 예측되는 바, 남측컨테이너철송장은 철도운영자와 철송장운영자를 통합하여 운영할 필요가 있다. 북항의 경우에는 신선대역의 역할이 중시되며 철도공사의 열차장대화에 맞는 시설의 확보와 부산진역 기능의 보완 기능 확보도 동시에 추진되어야 할 것이다. 아울러 철도로의 모달시프트에 대한 환경친화적인 정책적 지원방안의 강구도 필요하다.

• 에너지공학
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• 제23권3호
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• pp.181-185
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• 2014

본 논문은 카놀라 바이오디젤 혼합연료를 승용디젤엔진에 적용하였을 때 나타나는 연소 및 배기배출물 특성에 관한 연구이다. 본 연구에서는 카놀라 바이오디젤을 20%, 40%를 ULSD 80%, 60%와 체적비로 혼합한 혼합연료를 사용하여 ULSD 결과 데이터와 비교하였다. 엔진 회전속도, 엔진부하, 연료분사압력 변화를 실험변수로 사용하였으며. 카놀라 바이오 디젤의 혼합비가 증가 할수록 NOx 배출량은 증가하였지만, Soot 배출량은 감소하는 결과를 나타내었다. 또한 Soot 배출량은 낮은 연료분사압력에서 높은 배출량을 보였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.439-445
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• 2003

Since 1960s. container shipping volume has increased dramatically and continuous on a trend of rapid growth, and so the number of containers handled at the port increases. In order to improve yard crane operating efficiency, the precise position measurement of the yard crane is important. This paper describes the method to measure the absolute position of yard crane using the output pulse of an encoder and infrared sensors. The crane position is calculated by counting the output pulse of an incremental encoder, which is mounted on the wheel in the crane. By the way, the wheel slippage on rail may cause some errors in crane position information obtained from encoder pulses, and the errors in the crane position information are compensated with infrared sensors. The performance of proposed method is verified on experimental results with the simulator of yard crane, the size of which is about 1/10 with the real crane.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.58-64
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• 2003

Dimethyl Ether(DME) has been considered as one of the most attractive alternative fuels for compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has to be modified due to the physical properties of DME. Experimental study of DME and conventional diesel spray employing a common-rail type fuel injection system with a 5-hole sac type injector was performed in a constant volume vessel pressurized by nitrogen gas. Spray cone angles and penetrations of the DME spray were characterized and compared with those of diesel. For evaluation of the evaporating characteristics of the DME, shadowgraphy technique employing an Ar-ion laser and an ICCD camera was adopted. Tip of the DME spray was formed in mushroom-like shape at atmospheric chamber pressure, which disappeared in higher chamber pressure. Spray tip penetration and spray cone angle of the DME became similar to those of diesel under 3MPa of chamber pressure. Higher injection pressure provided wider vapor phase area while it decreased with higher chamber pressure condition.

• 한국연소학회지
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• 제16권4호
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• pp.1-7
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• 2011

The purpose of this study was to analyze the effect of pilot injection strategy on the combustion and emissions characteristics in a four cylinder common-rail direct injection diesel engine fueled with biodiesel(soybean oil) blend. The tested fuel was mixed of 20% biodiesel and 80% ULSD(Ultra low sulfur diesel) by volume ratio. The experiments were performed under two load conditions, and results were compared with those of single injection. The experimental results showed that the ignition delay of BD20 was shorter than compared to that of ULSD in the case of low load condition. Also, the fuel consumption of BD20 was more higher than that of ULSD. Fuel consumption by applied pilot injection strategy were generally decreased compared with that of single injection. In the case of pilot injection, the exhaust emissions such as CO and HC emissions were decreased compared to the single injection.

• 한국분무공학회지
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• 제18권2호
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• pp.73-80
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• 2013

The purpose of this study was compared the spray, combustion and emissions (NOx, CO, HC, smoke) characteristics of a typical fuel (100% Diesel, DME) and Diesel-DME blended fuel in a Constant Volume Chamber (CVC) and a single-cylinder DI diesel engine. Spray characteristics were investigated under various ambient and fuel injection pressures when the Diesel-DME blended ratio is varied. The parameters of spray sturdy were spray shape, penetration length, and spray angle. Common types of injectors having seven holes and made by Bosch were used. As of use, the typical fuel (100% Diesel, DME) and the blended fuel by mixture ratio 95:5, 90:10 (Diesel:DME) were used. The Injection pressure was fixed by 70.1MPa, when the ambient Pressure was varied 0.1, 2.6 and 5.1 MPa. The combustion experiments was conducted with single cylinder engine equipped with common rail injection system. injection pressure is 70 MPa. The amount of injected fuels is adjusted to obtain the fixed input calorie value as 972.2 J/cycle in order to compare with the fuel conditions.

• 한국생산제조학회지
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• 제24권2호
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• pp.203-210
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• 2015

This paper investigates the failure of a car with a 2.5-liter CRDi engine of the Hyundai Company. The failure is caused by intermittent poor acceleration while driving. To analyze the cause, we investigated the air intake volume, the fuel injection, and the air-fuel ratio, which were determined to be normal. The brake switch signal error was discovered while analyzing the function that limits the output of the engine. While investigating the cause, we discovered the corrosion of the pins on the connector of the brake switch. We determined that it was generated by soapy water flowing in the solar film. Therefore, the cause of the failure was the brake switch signal errors. Additionally, we determined that ECM was the normal fail-safe mode that implemented the override device for safety during normal acceleration. Based on these results, further solar film experiments must be conducted to fully elucidate the causes.

• 한국분무공학회지
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• 제19권1호
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• pp.9-14
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• 2014

Performance of DI diesel engine with high-pressure fuel injection equipment is directly related to its emission characteristics and fuel consumption. So, the electro-hydraulic injector for the common-rail injection system should be designed to meet the precise high fuel delivery control capability. Currently, most high pressure injector in use has a needle driven by the solenoid coil energy or the piezo actuator controlled by charge-discharge of output pulse current. In this study, macroscopic spray approaching method was applied under constant volume chamber to research the performance of three different injectors : solenoid, indirect-acting piezo and direct-acting piezo type for CR direct-injection. LED back illumination for Mie scattering was applied on the liquid spray visible of direct-acting piezo injector, including hydraulic-servo type solenoid and piezo-driven injectors. As main results, we found that a direct-acting piezo injector had better a spray tip penetration than hydraulic-servo injectors in spray visualization.