• Tribology and Lubricants
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• v.33 no.4
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• pp.153-167
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• 2017

The aim of this study is to find the change in trend in the eccentricities of two journal bearings supporting the crankshaft of a single cylinder engine and the degree of misalignment of the shaft. We analyze the change in oil film thickness considering the wear scar under mixed-elasto-hydrodynamic lubrication regime at potential wear regions. For this, we first calculate the central eccentricities of the two journal bearings by using the mobility method. Then we calculate the outer end eccentricity by using the geometry of the bearings. Further, the tilting angle and degree of misalignment of the shaft are calculated by using the eccentricities of the two bearings. We show that the eccentricity of bearing #1, on which higher load is applied, increases at the beginning of the start-up cycle and during the coast-down cycle. However, the eccentricity of bearing #2, on which lower load is applied, decreases at the beginning of the start-up cycle and increases during the coast-down cycle. From the results of the analysis of oil film thickness, we show that the mixed-elasto-hydrodynamic lubrication regime for a misaligned shaft is at the initial stages of the start-up cycle for both bearing #1 and #2 and at the final stage of the coast-down cycle for only bearing #1.

• Journal of Powder Materials
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• v.10 no.6
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• pp.383-389
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• 2003

As in other areas of materials technology, the tendency towards light weight constructions becomes more and more important also for powder metallurgy. The development is mainly driven by the automotive industry looking for mass reduction of vehicles as a major factor for fuel economy. Powder metallurgy has to offer a number of interesting areas including the development of sintered materials of light metals. PM aluminium alloys with improved properties are on the way to replace ferrous pars. For high temperature applications in the engine, titanium aluminide based materials offer a great potential, e.g. for exhaust valves. The PM route using elemental powders and reactions sintering is considered to be a cost effective way for net shape parts production. Furthermore it is expected that lower costs for titanium raw materials coming from metallurgical activities will offer new chances for sintered parts with titanium alloys. The field of cellular metals expands with the hollow sphere technique, that can provide materials of many metals and alloys with a great flexibility in structure modifications. These structures are expected to be used in improving the safety (crash absoption) and noise reduction in cars in the near future and offer great potential for many other applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.967-976
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• 2012

This study presents a model to minimize vibration and noise of powertrain mount on a compact car which has the application of Stop & Go performance, in order to reduce CO2 and achieve better fuel-efficiency in accordance with the environmental regulations in automotive industries. In the first step, we analyze the powertrain mount system of the automobile "A" and present variables about rubber stiffness applied on powertrain mount using the Taguchi method. In the next step, we verify the optimization of vibration and noise which meet Stop & Go performance using the AHP(Analytic Hierarchy Process) method on the proto products for each variable. Using this validation system on the initial stage of the powertrain mount design, it is expected that we can grasp vibration and noise problems caused by engine movements and control them effectively without engineering know-how about powertrain mount rubber stiffness.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.4002-4006
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• 2014

The automotive exhaust gases generated by the vehicles containing carbon monoxide, hydrocarbons and lead, is a large concern because of their harm to human health or the living environment. To reduce exhaust gas, it is important to develop a variety of techniques that are currently being used by elemental analysis to determine the optimal conditions. In this study, the anti-freeze coolant contained in the exhaust gas was examined, which can affect the emissions. The effects of the commercially available coolant from five domestic companies on the HC, NOx and $CO_2$ emissions were analyzed to determine the optimal amount of antifreeze. In addition, antifreeze products from the five companies were analyzed with respect to driving time of the cooling fan and the correlation of the NOx emission analysis. The temperature of the engine oil was matched using a manual gear of small passenger inspection standard speed $40{\pm}2Km/h$ so the vehicle could meet the specifications for inspection $90{\sim}93^{\circ}C$. The Company D fan operation time resulted in the shortest antifreeze, $CO_2$ and NOx emissions.

• Knowledge Management Research
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• v.17 no.2
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• pp.27-50
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• 2016

Korean manufacturing industry have recently faced the catch-up of China in the mass commodity product, such as automotive, display, and smart phone in terms of market as well as technology. Accordingly, discussion on the importance of achieving catch-up in complex product systems (CoPS) has been increasing as a new innovation engine for the industry. In order to achieve successful catch-up of CoPS, we explored emerging technologies of CoPS, which are featured by the characteristics of radical novelty, relatively fast growth and self-sustaining, through the study of emerging technologies of gas turbine for power generation. We found that emerging technologies of the gas turbine are technologies for combustion nozzle and composition of electrical machine for increasing power efficiency, washing technology for particulate matter, cast and material processing technology for enhancing durability from fatigue, cooling technologies from extremely high temperature, interconnection operation technology between renewable energy and the gas turbine for flexibility in power generation, and big data technology for remote monitoring and diagnosis of the gas turbine. We also found that those emerging technologies resulted in technological progress of the gas turbine by converging with other conventional technologies in the gas turbine. It indicates that emerging technologies in CoPS can be appeared on various technological knowledge fields and have complementary relationship with conventional technologies for technology progress of CoPS. It also implies that latecomers need to pursue integrated learning that includes emerging technologies as well as conventional technologies rather than independent learning related to emerging technologies for successful catch-up of CoPS. Our findings provide an important initial theoretical ground for investigating the emerging technologies and their characteristics in CoPS as well as recognizing knowledge management strategy for successful catch-up of latecomers. Our findings also contribute to the policy development of the CoPS from the perspective of innovation strategy and knowledge management.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1496-1502
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• 2012

The fuel pump mounted on the engine in the vehicle is consist of the outer and inter rotors, and which inhales fuel from the inlet port and supplies it to the outlet port. In this study, it is carried out the analysis and test of the fuel pump with rotors to evaluate its performance. It is analyzed the flow characteristics of the fuel pumps with numerical simulation in their inlet-outlet angles of 0, 15, 30 degree. After it is determined whether it has the best flow characteristics, its vibration characteristics is analyzed. The flow rate of a pump in the inlet-outlet angles of 0 degree is 191.0 LPH(Liter per hour) which is the largest. and its vibration is calculated to be 0.866 $^m/s^2$. In the results of vibration test, it is known that the vibration of the research pump is smaller than that of the existing one. And the natural frequencies of two pumps is nearly same. Therefore it is known that the performance of the research pump is superior.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.7
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• pp.759-765
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• 2012

This study investigates the effect of diesel combustion strategies on exhaust emissions and hydrocarbon species emissions for a 1.7 L common rail direct injection diesel engine at 1500 rpm and 3.9 bar BMEP. The first strategy is a method to adopt no EGR with a split injection composed of pilot and main injection (split injection). The second is to adopt a moderate EGR rate with main injection only (single-1). The third is to use a high level of EGR and main injection with rail pressure increase, $i.e.$ low-temperature diesel combustion (single-2). Split injection and single-1 showed a renowned phenomenon of a PM-NOx trade-off, whereas single-2 was observed of a PM-NOx trade-off to reduce PM and NOx simultaneously. HC speciation results show that the split injection produced the least amount of HC species, regardless of the carbon number bin, followed by single-1 and single-2. The ratios of methane, acetylene, and CO to THC increased as a combustion A/F ratio is richer due to reduced oxygen content in the vicinity of the combustion zone, thus enhancing pyrolysis.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.53-61
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• 2017

Turbocharger is a device for increasing the power of a vehicle engine. The control plate is the main component for fixing the vane of the turbocharger. Now, the control plate is made of austenite steel cutting after the casting process. It has excellent corrosion, heat resistance and mechanical characteristics of material. However, present the process is made by cutting after casting. when cutting is processed after casting, so materials, processing time, and processing energy are lost. Therefore, this study proposes a process to powder compact use of stainless steel Deklak2 and to minimize amount of cutting through net shape process. The mechanical properties of Deklak2 were verified by tensile test, hardness test and relative density measurement, and the governed equation was defined. Also, the curvature radius 1, 2 and the density, affects the shape, were selected as the design parameters, and the best process conditions was proposed through the Taguchi method and the evaluation of SN ratio. And then prototype molds were fabricated and compared with the results of the finite element analysis for the verification, and it was found that the tendency of relative density and dimension was coincided. Therefore, it was found that the amount of cutting can be minimized by only the net shape process after the sintering process and it can be applied to mass production.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1257-1263
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• 2010

The naval structure exposes to environmental vibration of shafted propeller propulsion and engine vibration. The shipboard equipments are developed compliance to MIL-STD-167-1A. For this purpose, vibration fatigue life of shipboard equipment for long lives should be estimate via an analytical approach and vibration test. In this paper, High cycle fatigue strength of cast aluminum alloy A356 using shipboard equipment was evaluated by 14 S-N method. The stress applied on the structure is evaluated by an analytical method(frequency response analysis with sinusoidal input and a fatigue evaluation) to simulate a MIL-STD-167-1A test. The frequency with the maximum equivalent stress is shown by Max. test frequency and the vibration fatigue life of shipboard equipment was estimated by Miner's rule.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.71-74
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• 2005

In manufacturing automotive parts, such as engine cradles, frame rails, subframes, cross-members, and other parts from circular tubes, pre-bending and pre-forming operations are often required prior to the subsequent tubular hydroforming process. During some pre-forming operations, the cross section of a bent circular tube is crushed into an oval-like shape to ensure proper geometry and sufficient clearance in the hydroforming dies. For such applications, the use of oval Instead of circular tubes could be an effective means of eliminating the pre-forming step. The oval tube could also be produced with less thinning and with less strain on the outside of the bend when controlled by a booster system without the use of mandrel. Hence, the understanding of the issues that occur in the bending of oval tubes is worthy of Investigation. This paper presents parametric studies on the bending of oval tubes without a mandrel. The finite element modeling technique is used to examine the deformation characteristics for both circular and oval tubes. In the simulations, the bending process parameters of bend radius, aspect ratio of the tube ovalness, and tube wall thickness are varied. Observations are made to obtain a hoop-buckle limit diagram in terms of a non-dimensional shape degradation factor. Suggestions based upon developed criteria are made on the acceptability of bend tubes suitable for hydroforming applications without the need ofa pre-forming step or the used of a mandrel.