• 한국기계가공학회지
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• 제17권3호
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• pp.65-70
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• 2018

M152, used for aircraft engine compressor cases, causes many problems in the cutting process due to its high hardness and high toughness. Characterized by a concave cylindrical center, aircraft engine compressor cases are thin but have multiple side holes to connect with internal parts. Thus, deformation occurs despite the jig sustaining the inside. The object of this study was to lessen the deformation arising from drilling by improving the drilling jig for aircraft engine compressor cases. To this end, an aircraft engine compressor case modeled with SolidWorks was analyzed with ANSYS under real conditions. Then, to secure reliability, the analyzed deformation was compared with the actual deformation. Based on the results, the effects of the improved drilling jig for aircraft engine compressor cases were verified.

• Tribology and Lubricants
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• 제17권6호
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• pp.447-452
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• 2001

In development process of engine lubrication system, many failure cases are related with aeration problem. Therefore, it is very important to clarify the aeration in the engine oil circuit system. As of today, many factors have been introduced as the major cause in the engine oil aeration. However, still many test data related with those are required to clearly understand it. In this paper the aeration measurement system and calculation method are introduced. And also using this system we measured engine oil aeration for various cases. From these results some conclusions are reduced.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.171-176
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• 2000

In development process of engine lubrication system, many failure cases are related with aeration problem. Therefore, it is very important to clarify the aeration in the engine oil circuit system. As of today, many factors have been introduced as the major cause in the engine oil aeration. However, still many test data related with those are required to clearly understand it. In this paper the aeration measurement system and calculation method are introduced. And also using this system we measured engine oil aeration fur various cases. From these results some conclusions are reduced.

• 수산해양교육연구
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• 제27권6호
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• pp.1734-1744
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• 2015

Majority of marine accidents that occur on fishing vessels are engine accidents. This comprises more than 26 % of the total annual fishing vessel marine accident cases. Large numbers of engine accidents happen in the cooling water system, which are mostly caused by negligence on regular check-up and repair. Notably, small-sized ships have higher engine accidents occurrence rate compared to medium-and large-sized ships. Based on the Report of the Korea Ship Safety Technology Authority, engine accident cases reached 3,032 out of the total 3,081 cases. This study researches on the differences between the small-sized ship pilot, an operator of a vessel engine of less than 200 tons, and a 6th level marine engineer, in terms of the relationship between management forms and what causes the marine accidents in association with the cooling water system. It also studies and analyzes the differences in frequency of the accident occurrence between the two groups. ${\chi}^2$ qualification was imposed through the SPSS statistical analysis program and it got qualified at the significance level of 5%. The research shall be utilized as one of the base line data for the reduction of marine accidents.

• 항공우주시스템공학회지
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• 제6권1호
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• pp.13-18
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• 2012

This paper presents a structural health monitoring method of aircraft reciprocating engine using Principal Component Analysis (PCA) which analyzes vibration expressed by Averaged Normalized Power Spectral Density (ANPSD). Because ANPSD of the rotating shaft is sensitive to the rotating speed, this paper proposes to use a post-processing method of ANPSD is used to reduce the sensitivity. The PCA extracts compressed information from the post-processed ANPSDs and the information means the difference between current and normal cases of the engine. The experimental results demonstrate the feasibility and effectiveness of the proposed method to detect abnormal cases of the engine.

• Environmental Engineering Research
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• 제14권2호
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• pp.95-101
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• 2009

Natural gas is a promising alternative fuel of internal combustion engines. In this paper, the combustion and emission characteristics were investigated on a natural gas engine at two different fuel injection timings during the intake stroke. The results show that fuel injection timing affects combustion processes. The optimum spark timing (MBT) achieving the maximum indicated mean effective pressure (IMEP) is related to fuel injection timing and air fuel ratio. At MBT spark timing, late fuel injection timing delays ignition timing and prolongs combustion duration in most cases. But fuel injection timing has little effect on IMEP at fixed lambdas. The coefficient of variation (COV) of IMEP is dependent on air fuel ratio, throttle positions and fuel injection timings at MBT spark timing. The COV of IMEP increases with lambda in most cases. Late fuel injection timings can reduce the COV of IMEP at part loads. Moreover, engine-out CO and total hydrocarbon (THC) emissions can be reduced at late fuel injection timing.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.61-64
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• 2017

한국형발사체에 적용되는 액체로켓엔진은 가스발생기 개방형 엔진 사이클을 채택한다. 가스발생기에서 연소 불안정이 발생하면 연소 성능이 변하고 진동, 소음 등의 문제점을 야기하거나 하드웨어의 손상을 초래할 수 있다. 본 연구에서는 액체로켓엔진의 가스발생기를 개발하면서 나타난 연소불안정 경험 사례를 소개하고자 한다.

• 센서학회지
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• 제31권1호
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• pp.51-56
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• 2022

In this study an efficient method for detecting and monitoring engine misfiring, focusing on minute speed changes in the crankshaft is proposed., Its validity is verified using various misfiring cases. Typically, the crankshaft speed fluctuates around the normal value depending on the engine misfiring status. Even a minute speed change in the crankshaft can be estimated by measuring the rotation time of each tooth of the 118-tooth flywheel attached to the crankshaft with a 2-MHz timer. Therefore, a speed pattern for an in-line six-cylinder engine consists of 236 tooth rotation speeds corresponding to the two rotations of the crankshaft, in which all the cylinders complete four-stroke cycle. FFT analysis can reduce the number of components of a speed pattern from 236 to just four major components: - fundamental frequency_(f), 2f, 3f, 6f., - This makes the comparison of the misfiring cases simpler and faster. In the experiment, five engine status cases (one normal firing and, four misfiring cases) were simulated. While the 6f component was the largest for the normal case, the f component increased as misfiring occurred one, two apart, and two consecutive times. The 3D FFT pattern comprising the ratio of f, 2f, and 3f, 6f showed that the distance between the misfiring and normal states was larger

• 한국자동차공학회논문집
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• 제18권5호
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• pp.56-61
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• 2010

This paper presents dynamic clearance verification considering engine movement for vehicle engine room package and validates through physical vehicle test. Traditionally, static clearance guide has been used for engine room package, but it's only 2-dimension criteria that results in requiring unnecessary space and it's not possible to conduct engine movement with real driving conditions. Thus, the dynamic DMU considers engine movement based on 28 load cases that are Roll Data analyzed by CAE for maximum engine movement and visualizes part-to-part dynamic clearance into virtual space. The dynamic DMU enables to develop compact engine room package without unnecessary space. The result of comparison between simulation and physical test has 0.892 correlation coefficient.

• International Journal of Automotive Technology
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• 제2권3호
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• pp.93-101
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• 2001

Distribution of fuel-air mixture has a strong influence on performance and emissions of a compressed natural gas (CNG) engine. In this paper, parametric study is performed by KIVA-3V to investigate fuel-air mixture with respect to injection timing, cycle equivalence ratio and engine speed. With open-valve injection intensive mixing during intake and compression stroke results in relatively homogeneous mixture in the cylinder. Sequential induction of fuel-air mixture and fresh air results in stratification in the cylinder among the test cases at closed-valve injection. There is close similarity in the calculated distributions of the mixture in the cylinder with different cycle equivalence ratios and engine speeds. The results are compared against pressure traces and flame images obtained in a single cylinder engine converted from a 11L six-cylinder heavy duty diesel engine.