• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1371-1379
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• 2003

The effects of change in injection pressure on spray structure in high temperature and pressure field have been investigated. The analysis of liquid and vapor phases of injected fuel is important for emissions control of diesel engines. Therefore, this work examines the evaporating spray structure using a constant volume vessel. The injection pressure is selected as the experimental parameter, is changed from 22 MPa to 112 MPa using a high pressure injection system (ECD-U2). Also, we conducted simulation study by modified KIVA-II code. The results of simulation study are compared with experimental results. The images of liquid and vapor phase for free spray were simultaneously taken by exciplex fluorescence method. As experimental results, the vapor concentration of injected fuel is leaner due to the increase of atomization in the case of the high injection pressure than in that of the low injection pressure. The calculated results obtained by modified KIVA-II code show good agreements with experimental results.

• 한국분무공학회지
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• 제13권2호
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• pp.65-72
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• 2008

It is recognized that alternative fuel such as dimethyl ether (DME) has better combustion polluting characteristics than diesel fuel, even though the cetane number of DME is almost the same as that of diesel. Characteristics of DME spray were observed experimentally under various ambient conditions using a constant volume chamber and a common-rail injection system. N-dodecane and LPG fuel sprays were also observed under same conditions of DME spray. Using spray images from backlight scattering and Mie scattering, characteristics of fuel sprays such as penetration and spray volume were visualized and quantitatively measured. The measurements showed that the penetration of early period decreased remarkably, because evaporation of alternative fuels became prosperous by the influence of flash boiling phenomenon under the condition of the low temperature and pressure compared with n-dodecane. The penetration of DME and LPG spray received the influence of temperature more largely in comparison with low density, because the specific surface area increased by atomizing in high density.

• 한국분무공학회지
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• 제22권3호
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• pp.116-121
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• 2017

Pre-combustion chamber type indirect diesel engines have different combustion characteristics compared with those of common rail direct injection engine. The CONVERGE, specific engine CFD program, was used to simulate hollow cone spray model and combustion. The air-fuel mixture flow propagating from pre-combustion chamber to cylinder was concentrated at top half and center of the pre-combustion chamber throat. Stronger mixture flow was formed at smaller and longer throat cases. As a result, thermal efficiency and fuel consumption were improved for modified throat shape and the soot emission was also reduced.

• 한국철도학회논문집
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• 제9권4호
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• pp.425-431
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• 2006

There are two kinds of police authorities in Korean railway industry, that is, the Special Judicial Police and the Local Subway Police. The existence of two separate entities for common objective of railway security has given rise to problems including inefficiency in performance and lack of customers-focused police service and synergic effects. The purpose of this study is to search for solutions to rail crimes that allows for rapid spatial movements since they take place on fast moving trains.

• 한국산업융합학회 논문집
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• 제19권3호
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• pp.154-159
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• 2016

Recently it has been focused that the automobile engine has developed in a strong upward tendency for the use of the high viscosity and poorer quality fuels in achieving the high performance, fuel economy, and emission reduction. Therefore it is not easy to solve the problems between low specific fuel consumption, and exhaust emission control at automotive engine In this study, it is designed and used the test bed which is installed with fuel injector controller. In addition to equipped engine using CRDI by controlling the injection timing with modulator, it has tested and analyzed the engine cycle variation characteristics, as it is varied that they are the operating parameters: fuel injected quantity, injection timing, engine speed and scavenging pressure.

• 한국산업융합학회 논문집
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• 제21권2호
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• pp.45-51
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• 2018

Compression ignition diesel engine can reduce carbon emission than gasoline engine in case of high efficiency, output and durability. So, compression ignition diesel engine is used in various fields such as automobiles, industries and so on. Due to reducing of emission exhaust by Developing of injection and combustion type of diesel engine, emission of pollution substance is developed compared the past. Moreover, its efficiency and reduce of carbon emission is better than gasoline engine and it is used in power source of industries, transports and others because of its high efficiency and durability nowadays. In this study, we experiment by making and designing of compression ignition diesel engine witch has air-cooling, 2 cylinder and 2 strokes.

• 동력기계공학회지
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• 제12권5호
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• pp.14-19
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• 2008

In order to meet stringent future emission regulations, especially to reduce Particulate Matter (PM) and NOX, stoichiometric diesel combustion technology with a piezo group-hole nozzle injector is being researched for reduction harmful emissions. A new nozzle layout, namely a group-hole nozzle, which has one group of small orifices with a wide spray included angle was investigated to improve the efficiency of stoichiometric diesel combustion. From this point of view, the group-hole nozzle suggested by Dense Co. is an attractive candidate method applicable to stoichiometric diesel combustion. The group-hole nozzle concept is to reduce the injector nozzle hole diameters without sacrificing spray penetration by closely locating two holes. Experimental studies have proven that the spray from group-hole nozzles have similar spray penetration to that of a single hole with equivalent overall nozzle hole area, but the spray drop sizes (SMD) are reduced, aiding vaporization and mixing.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1284-1292
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• 2015

As visual surveillance systems become more and more common in human lives, approaches based on these systems to solve security problems in practice are boosted, especially in railway applications. In this paper, we first propose a robust snag detection algorithm and then present a railway security system by using a combination of multiple sensors and the vision based snag detection algorithm. The system aims safety at several repeatedly occurred situations including slope protection, inspection of the falling-object from bridges, and the detection of snags and foreign objects on the rail. Experiments demonstrate that the snag detection is relatively robust and the system could guarantee the security of the railway through these real-time protections and detections.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 춘계학술대회
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• pp.321-324
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• 2013

디젤엔진에서 노킹 현상은 엔진의 성능 및 수명에 직접적인 영향을 주는 중요한 인자이며, 엔진 밸런스 또한 엔진 출력 및 내구성에 직접적인 영향을 미치는 중요한 인자이다. 따라서 노킹 진단 및 엔진 밸런스 보정 알고리즘을 적용하여 ECU를 최적화 하고자 한다. 또한 OBD-II 표준을 사용하여 차량 위주의 진단기를 개발하여 운전자 중심의 진단 서비스를 제공하며, 자동차 고장진단 신호 및 센서 출력 신호를 실시간 통신이 제공 될 수 있게 한다. 이를 위해 자동차 고장진단 신호 및 센서출력 신호를 유선시스템과 무선 시스템인 블루투스 모듈을 이용하여 실시간 통신이 제공 될 수 있는 OBD-II 진단기 S/W를 설계 및 구현하였다.

• 한국분무공학회지
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• 제19권3호
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• pp.123-129
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• 2014

A diesel spray overall SMD (Sauter mean diameter) in a spray chamber was simulated with CFD by varying the compression ratio in the spray chamber from 18:1 to 100:1. The gas densities of the spray chambers for the compression ratios of 18:1 and 100:1 were 17.97 and $74.8kg/m^3$, respectively. Standard KIVA-3V code was used for the CFD simulation. Various fuel injection patterns such as single injection, pilot injection and split injection were used for the CFD simulation. Fuel injection pressures for the simulated diesel sprays are 90 and 120 MPa. As the compression ratio increases, the CFD simulated SMD was decreased, which was generally in agreement with previous experimental studies.