• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2006년도 제27회 추계학술대회논문집
• /
• pp.339-343
• /
• 2006

호주의 HyShot Center와의 공동연구를 통한 모델 스크램제트 엔진의 지상시험 수행을 위해 홉입구의 설계를 수행하였다. 본 흡입구는 연소기로 고온, 저속의 유동을 공급하는 방향으로 설계되었으며 Korkegi 관계식에 따라 충격파 결집구간을 분리함으로써 유동 박리현상을 차단하였다. 또한 Kantrowitz 관계식에 근거하여 자발시동이 가능하도록 흡입구 측면의 트임구간을 설정하였다.

• 디지털융복합연구
• /
• 제17권11호
• /
• pp.207-213
• /
• 2019

대부분의 차량에 적용되어 있는 연료차단(fuel-cut) 관성주행은 변속기어 체결 상태에서 가속페달을 방치할 때 자동으로 작동하게 된다. 이 때 연료분사가 일시적으로 중단되므로 연비 향상 효과가 상당하다. 본 연구에서는 GPS를 이용하여 측정된 차속, 가속도, 도로구배 등의 신호를 바탕으로 하는 연료차단 관성주행 감지법을 제안하였다. 관성 주행시 작용하는 주행저항력에 의해 계산되는 가속도값과 GPS에서 실시간으로 측정되는 가속도값을 비교하는 방식이다. 실도로 주행 데이터를 측정하여 이 감지법을 평가한 결과 약 80% 수준의 정확도를 얻을 수 있었다. 도로구배가 다소 큰 12km 정도의 국도를 16분 동안 주행하면서 측정한 약 9,600개의 속도, 가속도, 도로구배 및 연료소모량 데이터에 감지법을 적용하여 얻은 결과이다. 인젝터 분사파형 분석을 위한 배선작업 등이 불필요하여 간단하게 연료차단여부를 판정할 수 있는 장점이 있다. 다만, 속도, 가속도 및 도로구배의 변화율이 연료소모량의 변화율에 비해 훨씬 크게 나타나기 때문에 감지법의 오차도 다소 증가하는 것을 알 수 있었다.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년도 춘계학술대회논문집
• /
• pp.345-348
• /
• 2008

The computer-aided performance simulation can reduce periods for development of products and cut down on the cost comparing with former trial-and-error procedures. This study has developed a simulation program for a vehicle thermal management system integrating an engine cooling system and an air conditioning system considering interactions and arrangement of air side heat exchangers such as power steering oil cooler, air-cooled transmission oil cooler, condenser, and radiator. The program may be also used for the system performance analysis according to the configuration of the engine coolant side heat exchangers such as water-cooled transmission oil cooler, EGR cooler, and heater core. Experiments utilizing an environmental wind tunnel has been conducted to assess the performance of the system according to the arrangement of air side heat exchangers. Some modification of the coolant loop layout can enhance the heat core performance up to 7% according to the results of the simulations.

• 한국자동차공학회논문집
• /
• 제12권1호
• /
• pp.74-82
• /
• 2004

Planar laser-induced fluorescence(PLIF) has been widely used to obtain two dimensional fuel distribution. Acetone PLIF is chosen because fluorescence signal from acetone as a fluorescent tracer is less sensitive to oxygen quenching than other dopants. Acetone PLIF is applied to measure quantitative air excess ratio distribution in an engine fueled with LPG. Acetone is excited by KrF excimer laser (248nm) and its fluorescence image is acquired by ICCD camera with a cut-off filter to suppress Mie scattering from the laser light. For the purpose of quantifying PLIF signal, an image processing method including the correction of laser sheet beam profile is suggested. Raw images are divided by each intensity of laser energy and profile of laser sheet beam. Inhomogeneous fluorescence images scaled with the reference data, which is taken by a calibration process, are converted to air excess ratio distribution. This investigation shows instantaneous quantitative measurement of planar air excess ratio distribution for gaseous fuel.

• Journal of Advanced Marine Engineering and Technology
• /
• 제8권1호
• /
• pp.17-36
• /
• 1984

Since 1973, the competition on the development of fuel saving type internal combustion engines has become severe by the two times oil shock, and new type engines are reported every several months. Whenever these new type engines are developed, new designs are required and they will be offered in the market after performing the endurance test for a long time. But the engine market is faced with a heavy burden of finance, as the developing of a new engine requires tremendous expenses. For this reason, the computer simulation method has been lately developed to cope with it. The computer simulation method can be available to perform the reasonable research works by the theoretical analysis before carrying out practical experiments. With these processes, the developing expenses are cut down and the period of development is curtailed. The object of this study is the development of simulation computer program for the small naturally aspirated four-stroke diesel engine which is intended to product by the original design of our country. The process of simulation is firstly investigated for the ideal engine cycle, and secondly for the real engine cycle. In the ideal engine cycle, each step of the cycle is simulated by the energy balance according to the first law of thermodynamics, and then the engine performance is calculated. In the real cycle imulation program, the injection rate, the preparation rate and the combustion rate of fuel and the heat transfer through the wall of combustion chamber are considered. In this case, the injection rate is supposed as constant through the crank angle interval of injection and the combustion rate is calculated by the Whitehouse-Way equation and the heat transfer is calculated by the Annand's equation. The simulated values are compared with measured values of the YANMAR NS90(C) engine and Mitsubishi 4D30 engine, and the following conclusions are drawn. 1. The heat loss by the exhaust gas is well agree with each other in the lower load, but the measured value is greater than the calculated value in the higher load. The maximum error rate is about 15% in the full load. 2. The calculated quantity of heat transfer to the cooling water is greater than the measured value. The maximum error rate is about 11.8%. 3. The mean effective pressure, the fuel consumption, the power and the torque are well agree with each other. The maximum error is occurred in the fuel consumption, and its error rate is about 7%. From the above remarks, it may be concluded that the prediction of the engine performance is possibly by using the developed program, although the program needs to reform by adding the simulation of intake and exhaust process and assumping more reliable mechanical efficiency, volumetric efficiency, preparation rate and combustion rate.

• 한국자동차공학회논문집
• /
• 제8권1호
• /
• pp.85-91
• /
• 2000

Oxygen sensors taken from the aftertreatment systems of 4 vehicles which had been aged in domestic filed were examined for aging pattern using a idle engine bench. The sensors were then cut into each layers along their components and characterized for poisoning, surface area and morphology. This study shows that amplitude and mean value of aged sensors are seriously affected by high temperature and oil components of exhaust gas.

• 수산해양교육연구
• /
• 제4권2호
• /
• pp.101-108
• /
• 1992

This study is some parts, the contents on "Course of Power Machinery and of Automated-Ship Operation", of the results of the sixth curriculum, revision study for the fisheries high schools and merchant marine high schools. In this study, it was suggested that the existing name "the Course of Marine Engine" is revised to "the Course of Power Machinery" and "the Course of Automated-Ship Operation" is newly established. The purpose of the revision of the name to "the Course of Power Machinery" is to give the course a more flexible curriculum which enables the course to bring up not only sea duty marine engineers but also shore duty power engineers. Also, the purpose of the new establishment of "the Course of Automated-Ship Operation" is to bring up automated-ship operators. The necessities for automated-ship operator is derived from the process of ship automation to reduce the number of crew to cut down the expenses. The revised parts of the organization of the professional subjects exclusively related to "the Course of Power Machinery" and "the Course of Automated-Ship Operation" are summarised as follows; (l) The Automated-Ship are newly added. (2) The Sea Training, the Fisheries Law are Disused. (3) The Introduction to Ship, the Introduction to Marine Engine and the Introduction to Marine Communication are merged into the Introduction to Ship. (4) The name of the Marine Engine, the Shipping Business are revised to the Heat Engine, the Introduction to Shipping respectively. (5) M compulsory professional subjects, the Introduction to Fisheries is suggested for the fisheries high schools and the Introduction to Shipping is suggested for the merchant marine high schools.

• Journal of Advanced Marine Engineering and Technology
• /
• 제29권2호
• /
• pp.185-193
• /
• 2005

The present study composed a diesel-atkinson cycle of high expansion as a method of achieving high efficiency in diesel cycle engines. It also interpreted the cycle engine thermodynamically analysis to determine the possibility of the improvement of thermal efficiency and clarified the characteristics of several factors . According to the result of theoretical analysis, heat efficiency was highest when expansion-compression ratio Reど:1. In addition. diesel engines with high apparent compression ratio had higher expansion-compression ratio than otto engines and consequently their effect of high expansion was high. which in turn enhanced thermal efficiency. When the atkinson cycle was implemented in a real diesel engine by applying the miller cycle through the variation of the closing time of the intake valve, the effective compression ratio and the quantify of intake air decreased and as a result, the effect of high expansion was not observed. Accordingly. the atkinson cycle can be implemented when the quantity of intake air is compensated by supercharge and the effective compression ratio is maintained at its initial level through the reduction of the clearance volume. In this case. heat efficiency increased by $4.1\%$ at the same expansion-compression ratio when the apparent compression ratio was 20 and the fuel cut off ratio was 2. As explained above, when the atkinson cycle was used for diesel cycle. heat efficiency was improved. In order to realize high expansion through retarding the intake value closing time, the engine needs to be equipped with variable valve timing equipment, variable compression ratio equipment and supercharged Pressure equipment. Then a diesel-atkinson cycle engine is realized.

• 전기전자학회논문지
• /
• 제17권4호
• /
• pp.525-530
• /
• 2013

워크플로우의 표준인 BPEL은 프로그래밍 언어에 대한 이해도가 낮은 도메인 전문가도 손쉽게 비즈니스 흐름을 작성할 수 있다. 하지만 특정 도메인에서는 BPEL 문법에 없는 새로운 기능이 요구된다. BPEL 엔진이 새로운 기능을 처리하기 위해서는 새로운 BPEL 엔진을 개발하거나 기존의 BPEL 엔진에 기능을 추가해야 하는데 이는 비용이 많이 필요하다. 본 논문에서는 XML 스키마를 확장하여 XAS4B 문서를 제안하고 관점지향 프로그래밍 기법을 이용하여 BPEL 엔진에 새로운 기능을 추가하는 방법을 보인다. 관점지향 프로그래밍 기법은 직조를 이용하여 핵심관심사의 수정없이 횡단관심사를 추가할 수 있다. 본 연구에서는 기존의 BPEL 엔진으로 B2J (BPEL to JAVA)를 사용하는데 이 엔진은 BPEL 문서를 JAVA 프로그램으로 변환하고 이를 실행한다. 본 시스템은 B2J 엔진이 생성한 JAVA 프로그램을 핵심관심사로 새로운 기능을 처리하는 프로그램을 횡단관심사로 두 프로그램을 직조하여 BPEL 흐름에 새로운 기능의 흐름을 추가한다. 제안하는 방법은 BPEL의 새로운 기능을 추상적으로 제공하여 한 번 개발된 새로운 기능을 도메인 전문가가 재사용하기 손쉽다.

• 산업경영시스템학회지
• /
• 제44권3호
• /
• pp.86-97
• /
• 2021

As mechatronic systems have various, complex functions and require high performance, automatic fault detection is necessary for secure operation in manufacturing processes. For conducting automatic and real-time fault detection in modern mechatronic systems, multiple sensor signals are collected by internet of things technologies. Since traditional statistical control charts or machine learning approaches show significant results with unified and solid density models under normal operating states but they have limitations with scattered signal models under normal states, many pattern extraction and matching approaches have been paid attention. Signal discretization-based pattern extraction methods are one of popular signal analyses, which reduce the size of the given datasets as much as possible as well as highlight significant and inherent signal behaviors. Since general pattern extraction methods are usually conducted with a fixed size of time segmentation, they can easily cut off significant behaviors, and consequently the performance of the extracted fault patterns will be reduced. In this regard, adjustable time segmentation is proposed to extract much meaningful fault patterns in multiple sensor signals. By considering inflection points of signals, we determine the optimal cut-points of time segments in each sensor signal. In addition, to clarify the inflection points, we apply Savitzky-golay filter to the original datasets. To validate and verify the performance of the proposed segmentation, the dataset collected from an aircraft engine (provided by NASA prognostics center) is used to fault pattern extraction. As a result, the proposed adjustable time segmentation shows better performance in fault pattern extraction.