EFFECT OF FUEL INJECTION STRATEGIES ON THE COMBUSTION PROCESS IN A PFI BOOSTED SI ENGINE

S. S. MEROLA,P. SEMENTA,C. TORNATORE,B. M. VAGLIECO 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.5

A low-cost solution based on fuel injection strategies was investigated to optimize the combustion process in a boosted port fuel injection spark ignition (PFI SI) engine. The goal was to reduce the fuel consumption and pollutant emissions while maintaining performance. The effect of fuel injection was analyzed for the closed and open valve conditions, and the multiple injection strategies (MIS) based on double and triple fuel injection in the open-valve condition. The tests were performed on an optical accessible single-cylinder PFI SI engine equipped with an external boost device. The engine was operated at full load and with a stoichiometric ratio equivalent to that of commercial gasolines. Optical techniques based on 2D-digital imaging were used to follow the flame propagation from the flame kernel to late combustion phase. In particular, the diffusion-controlled flames near the valves and cylinder walls, due to fuel deposition, were studied. In these conditions, the presence of soot was measured by two-color pyrometry, and correlated with engine parameters and exhaust emissions measured by conventional methods. The open valve fuel injection strategies demonstrated better combustion process efficiency than the closed ones. They provided very low soot levels in the combustion chamber and engine exhaust, and a reduction in specific fuel consumption. The multiple injection strategies proved to be the best solution in terms of performance, soot concentration, and fuel consumption. A low-cost solution based on fuel injection strategies was investigated to optimize the combustion process in a boosted port fuel injection spark ignition (PFI SI) engine. The goal was to reduce the fuel consumption and pollutant emissions while maintaining performance. The effect of fuel injection was analyzed for the closed and open valve conditions, and the multiple injection strategies (MIS) based on double and triple fuel injection in the open-valve condition. The tests were performed on an optical accessible single-cylinder PFI SI engine equipped with an external boost device. The engine was operated at full load and with a stoichiometric ratio equivalent to that of commercial gasolines. Optical techniques based on 2D-digital imaging were used to follow the flame propagation from the flame kernel to late combustion phase. In particular, the diffusion-controlled flames near the valves and cylinder walls, due to fuel deposition, were studied. In these conditions, the presence of soot was measured by two-color pyrometry, and correlated with engine parameters and exhaust emissions measured by conventional methods. The open valve fuel injection strategies demonstrated better combustion process efficiency than the closed ones. They provided very low soot levels in the combustion chamber and engine exhaust, and a reduction in specific fuel consumption. The multiple injection strategies proved to be the best solution in terms of performance, soot concentration, and fuel consumption.

A Study of Operating the Engineering Accreditation System to Contribute to Improving Rate of Employment

손호재 한국공학교육학회 2016 공학교육연구 Vol.19 No.2

The employment rate of a college has long been one of the most important elements in college survival strategies. Employment rates may not be key to colleges’ survival in other countries, but they are fundamental to colleges in Korea as seen in the Korean government-led National Competency Standard (NCS), which has been underway since its introduction to colleges in Korea. Against this backdrop, if the engineering accreditation system can contribute to improving employment rate in this context, it can take root more quickly. The process conducive to improving employment rates can be classified as both direct and indirect methods. With dwindling school-age population having impacts on colleges and universities, the environment and the education directions of colleges have rapidly been shifting since the introduction of the NCS. Therefore, various survival strategies for colleges need to be developed. An indicator of employment rate of college graduates is among the most important things during this transition process. The Department of Mechanical Engineering at Koje College has consistently shown good records during the past 5 years by matching the accreditation schemes and employment strategies. The department will help put in place the engineering technology education accreditation system at the college through its various innovative and effective programs. To formulate a better employment strategy, it is needed to reflect and consolidate the engineering accreditation scheme into the existing employment policy of college. In short, this paper examines both the engineering accreditation scheme and the employment policy in ways that helps produce a coupling matrix structure. This study looks into the measures for improving employment rates by better adjusting the engineering education methods under the accreditation scheme.

공과대학생의 쓰기 효능감이 쓰기 메타인지전략과 쓰기 불안에 미치는 영향

황순희(Soonhee Hwang) 한국공학교육학회 2023 공학교육연구 Vol.26 No.2

This research aims to examine the role of writing self-efficacy in engineering students’ writing metacognitive strategies and writing apprehension. To achieve this purpose, first, the relationships among writing self-efficacy, writing metacognitive strategies and writing apprehension were investigated. Second, the effects of writing self-efficacy, as perceived by engineering students, on writing metacognitive strategies as well as writing apprehension were explored. A total of 173 engineering students from one university in Korea responded to survey based on a three-variables scale. The findings were that, firstly, positive correlations between writing self-efficacy and writing metacognitive strategies were identified in terms of sub-factors of those two variables. Secondly, negative correlations between writing apprehension and writing self-efficacy, and between writing apprehension and writing metacognitive strategies, were identified in terms of sub-factors of those variables. Thirdly, writing self-efficacy predicted engineering students’ writing metacognitive strategies’ sub-factors and writing apprehension. The practical implications of these findings are discussed herein, with particular attention on education for promotion of writing self-efficacy and reduction of writing apprehension.

국내 건설엔지니어링 업체의 대외경쟁력 저하원인 분석을 통한 해외 진출 활성화 방안

박환표,조문영,박상훈 한국건설관리학회 2004 한국건설관리학회 논문집 Vol.5 No.6

The construction engineering field is less than 3~5% of the gross construction cost, but engineering's role is very important because the performance of final facility is decided in the engineering stage.Nevertheless, before now government and private companies are more concentrated on construction works than making strategy to strengthen the competitiveness and technical development of investment in construction engineering sectors.Therefore this research have compared and analyzed the competitiveness of domestic construction engineering companies throughout analytic method 'SWOT' to those developing countries, which are potential big market objects, such as Russia, Libya and Indonesia. Such research was obtained through business trip & consultation with related specialists for the difficulties of domestic companies in advancing into overseas market.Moreover this research have analyzed the technical improvement of construction engineering companies and reason for competitiveness weaken by various aspects, it provides governmental and private plans to advance into overseas market. Especially, to strengthen domestic companies into advancing overseas market, it has suggested that tax & subsidy privileges, supporting plans for obtaining information of overseas and strategic cooperation with other organizations.

공학수업에서 학생들이 지각하는 교수전략과 학습전략 간의 관계

이성혜(Lee, Sunghye),최경애(Choi, Kyoung Ae) 한국공학교육학회 2018 공학교육연구 Vol.21 No.5

The purpose of this study was to investigate the relationship between instructional strategies applied to engineering courses and students learning strategies. As a result, students perceived that the application principle was the most applied and then the problem-centered principle was applied to engineering courses. In addition, the students showed that rehearsal strategies are the most used in courses. The most important instructional principle in this study was the problem-centered principle, and the higher the degree of application of problem-centered principle in engineering course, the students were likely to use more deep learning strategies such as elaboration and organization strategy, critical thinking strategy, and metacognitive strategy.

A Study of Operating the Engineering Accreditation System to Contribute to Improving Rate of Employment

Ho-Jae Son(손호재) 한국공학교육학회 2016 공학교육연구 Vol.19 No.2

The employment rate of a college has long been one of the most important elements in college survival strategies. Employment rates may not be key to colleges’ survival in other countries, but they are fundamental to colleges in Korea as seen in the Korean government-led National Competency Standard (NCS), which has been underway since its introduction to colleges in Korea. Against this backdrop, if the engineering accreditation system can contribute to improving employment rate in this context, it can take root more quickly. The process conducive to improving employment rates can be classified as both direct and indirect methods. With dwindling school-age population having impacts on colleges and universities, the environment and the education directions of colleges have rapidly been shifting since the introduction of the NCS. Therefore, various survival strategies for colleges need to be developed. An indicator of employment rate of college graduates is among the most important things during this transition process. The Department of Mechanical Engineering at Koje College has consistently shown good records during the past 5 years by matching the accreditation schemes and employment strategies. The department will help put in place the engineering technology education accreditation system at the college through its various innovative and effective programs. To formulate a better employment strategy, it is needed to reflect and consolidate the engineering accreditation scheme into the existing employment policy of college. In short, this paper examines both the engineering accreditation scheme and the employment policy in ways that helps produce a coupling matrix structure. This study looks into the measures for improving employment rates by better adjusting the engineering education methods under the accreditation scheme.

Current strategies for treatment of intervertebral disc degeneration: substitution and regeneration possibilities

Sebastião van Uden,Joana Silva-Correia,Joaquim Miguel Oliveira,Rui Luís Reis 한국생체재료학회 2017 생체재료학회지 Vol.21 No.4

Background: Intervertebral disc degeneration has an annual worldwide socioeconomic impact masked as low back pain of over 70 billion euros. This disease has a high prevalence over the working age class, which raises the socioeconomic impact over the years. Acute physical trauma or prolonged intervertebral disc mistreatment triggers a biochemical negative tendency of catabolic-anabolic balance that progress to a chronic degeneration disease. Current biomedical treatments are not only ineffective in the long-run, but can also cause degeneration to spread to adjacent intervertebral discs. Regenerative strategies are desperately needed in the clinics, such as: minimal invasive nucleus pulposus or annulus fibrosus treatments, total disc replacement, and cartilaginous endplates decalcification. Main body: Herein, it is reviewed the state-of-the-art of intervertebral disc regeneration strategies from the perspective of cells, scaffolds, or constructs, including both popular and unique tissue engineering approaches. The premises for cell type and origin selection or even absence of cells is being explored. Choice of several raw materials and scaffold fabrication methods are evaluated. Extensive studies have been developed for fully regeneration of the annulus fibrosus and nucleus pulposus, together or separately, with a long set of different rationales already reported. Recent works show promising biomaterials and processing methods applied to intervertebral disc substitutive or regenerative strategies. Facing the abundance of studies presented in the literature aiming intervertebral disc regeneration it is interesting to observe how cartilaginous endplates have been extensively neglected, being this a major source of nutrients and water supply for the whole disc. Conclusion: Several innovative avenues for tackling intervertebral disc degeneration are being reported – from acellular to cellular approaches, but the cartilaginous endplates regeneration strategies remain unaddressed. Interestingly, patientspecific approaches show great promise in respecting patient anatomy and thus allow quicker translation to the clinics in the near future.

Effects of engine loads on emission gases and particulate matter with morphological characteristics in a commonrail 4 cylinder diesel engin

노현구,이창식,최석천 한국연소학회 2010 한국연소학회지 Vol.15 No.3

The purpose of this paper is to investigate the effects of fuel injection strategy and engine load on the structure and emissions characteristics of a DI diesel engine with 1.6L of piston displacement. In order to analyze the particulate matter (PM) and exhaust emissions characteristics in a direct injection diesel engine, the quantity of PM and exhaust emissions (including HC, CO and NOX) were investigated under various injection strategies and engine loads. Two different injection strategies (one pilot/main injection and two pilots/main injection)was investigated under the various engine loads. A thermophoretic sampling method with a scanning electron microscope (SEM) were used to obtain the PM morphology (including primary particles, the size of the agglomerates,the number of agglomerates, the fractal dimension). The quantity of soot gradually increased with increasing engine load at both injection strategies. The primary particles in the PM agglomerates indicate that the average of the primary particle and radius of gyration increased as the engine load increased.

A Case Study on Architectural Engineering Design Using Action Learning

장명훈,최희복 한국건축시공학회 2013 한국건축시공학회지 Vol.13 No.1

Companies want universities to produce graduates with creativity and problem-solving skills, and for this reason universities have extended engineering design education, including in the field of architectural engineering. This paper investigates an engineering design class in the Department of Architectural Engineering, J University. The class was taught in 2010 and 2011using an Action Learning (AL) teaching-learning strategy. The students responded that the level of participation and satisfaction was high in the Action Learning classes, and role allocation or responsibility and communication of the project teams were very effective. But it was also found that as Action Learning is such a new method for students of engineering design, an orientation session that describes what to do and what to prepare should be given before the class starts.

Effects of Engine Loads on Exhaust Emissions and Particulate Matter with Morphological Characteristics in a Common Rail 4 Cylinder Diesel Engine

Hyun Gu Roh,Seuk Cheun Choi,Chang Sik Lee 한국연소학회 2010 한국연소학회지 Vol.15 No.3

The purpose of this paper is to investigate the effects of fuel injection strategy and engine load on the structure and emissions characteristics of a DI diesel engine with 1.6L of piston displacement. In order to analyze the particulate matter (PM) and exhaust emissions characteristics in a direct injection diesel engine, the quantity of PM and exhaust emissions (including HC, CO and NOX) were investigated under various injection strategies and engine loads. Two different injection strategies (one pilot/main injection and two pilots/main injection) was investigated under the various engine loads. A thermophoretic sampling method with a scanning electron microscope (SEM) were used to obtain the PM morphology (including primary particles, the size of the agglomerates, the number of agglomerates, the fractal dimension). The quantity of soot gradually increased with increasing engine load at both injection strategies. The primary particles in the PM agglomerates indicate that the average of the primary particle and radius of gyration increased as the engine load increased.