• Tribology and Lubricants
• /
• v.31 no.5
• /
• pp.205-212
• /
• 2015

In this research, effects of profile changes of stem section of the plunger on the lubrication characteristics of a fuel injection pump (FIP) were evaluated by hydrodynamic lubrication analysis. The clearance between plunger and barrel was divided into two regions, head and stem. The head was not involved in preventing a decrease of fuel oil pressure. So, research efforts were focused on both edges of the plunger’s stem. The two -dimensional Reynolds equation was used to evaluate lubrication characteristics with variations in viscosity, clearance and profile for a laminar, incompressible, unsteady-state flow. Moreover, the equilibrium equation of moment and forces in the vertical and horizontal directions were used to determine the motion of the plunger. The equations were discretized using the finite difference method. Lubrication characteristics of the FIP were investigated by comparing the dimensionless minimum film thickness, or film parameter, which is the ratio of minimum film thickness to surface roughness. Through numerical analyses, we showed that the profile of the lower edge of the stem had no effect on lubrication characteristics, but the profile of the upper edge had a significant influence on lubrication characteristics. In addition, changes in the profile were more effective in improving lubrication characteristics under low viscosity conditions.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2002.10a
• /
• pp.293.2-293
• /
• 2002

• Transactions of Materials Processing
• /
• v.15 no.3 s.84
• /
• pp.226-231
• /
• 2006

The fuel injector is a pa.1 that controls the fuel supply of automotive engine. The housing of the fuel injector supports the rod, the needle valve and the solenoid. In this study, the rigid-plastic FE-analysis by using the design of experiments (DOE) and the response surface methodology (RSM) has been performed to produce the product reducing the under-fill and the maximum effective strain. From the results of DOE, the stem of counter punch and the face angle of punch at the $1^{st}$ process, and the stem of punch at the $2^{nd}$ process were determined as the significant design variables far each response such as the upper under-fill, lower under-fill and the maximum effective strain. From the results of RSM, the optimal values of the design variables have been also determined by simultaneously considering the responses.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.59 no.5
• /
• pp.17-23
• /
• 2017

In South Korea, 25 % of annual agricultural residues (11.64 million tons) are unused. The hydrophilicity, low lower heating value (LHV), and low energy density of agricultural residues can be obstacles for efficient usage. Torrefaction, a low temperature pyrolysis process, can be a solution to overcome these disadvantage of agricultural residues. In this study, agricultural residues such as bean stem, pepper stem, perilla stem, sorghum stem, acorn shell, and ginkgo shell are torrefied at 200, 230, and $250^{\circ}C$ and evaluated energy properties, respectively. The torrefaction can increase the LHV and energy density rate of agricultural residues from 3,331~4,444 kcal/kg to 4,166~5,830 kcal/kg and 20~30 %, respectively.

• Tribology and Lubricants
• /
• v.31 no.6
• /
• pp.245-250
• /
• 2015

This study investigates the lubrication characteristics of fuel injection pumps with reference to different fuel oils. Medium-speed diesel engines use fuel oils with various viscosities, such as heavy fuel oil (HFO, which is a high-viscosity fuel oil) and light diesel oil (LDO, which is a low-viscosity fuel oil). When fuel oil with a low viscosity is used, both fuel oil and lubricating oil lubricate the system. Thus, the lubrication of the fuel injection pump is in a multi-viscosity condition when the fuel oil in use changes. We suggest three cases of multi-viscosity models, and divide the fuel injection pump into three lubrication sections: a, the new oil section; b, the mixed oil section; and c, the used oil section. This study compares the lubrication characteristics with variation of the multi-viscosity model, clearance. The volume of Section b does not affect the lubrication characteristics. The lubrication characteristics of the fuel injection pump are poor when high-viscosity fuel oil transfers to low-viscosity fuel oil. This occurs because the viscosity in the new oil section (i.e., Section a) dominates the lubrication characteristics of the fuel injection pump. However, the lubricant oil supply in the used oil section (i.e., Section c) can improve the lubrication characteristics in this condition. Moreover, the clearances of the stem and head significantly influence the lubrication characteristics when the fuel oil changes.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.3
• /
• pp.275-285
• /
• 2003

A visualization study on the effect of forcing amplitude in tone-excited jet diffusion flames has been conducted. Visualization techniques are employed using optical schemes. which are a light scattering photography. Flame stability curve is attained according to Reynolds number and forcing amplitude at a fuel tube resonant frequency. Flame behavior is globally grouped into two from attached flame to blown-out flame according to forcing amplitude: one sticks the tradition flame behavior which has been observed in general jet diffusion flames and the other shows a variety of flame modes such as the flame of a feeble forcing amplitude where traditionally well-organized vortex motion evolves, a fat flame. an elongated flame. and an in-burning flame. Particular attention is focused on an elongation flame. which is associated with a turnabout phenomenon of vortex motion and on a reversal of the direction of vortex roll-up. It is found that the flame length with forcing amplitude is the direct outcome of the evolution process of the formed inner flow structure. Especially the negative part of the acoustic cycle under the influence of a strong negative pressure gradient causes the shapes of the fuel stem and fuel branch part and even the direction of vortex roll-up to dramatically change.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.53 no.2
• /
• pp.61-65
• /
• 2011

Biomass is considered to be a major potential fuel and renewable resource for the future. In fact, there is high potential to produce the large amount of energy from biomass around the world. In this study, to obtain basic data for practical application of agricultural and forest by-products as fuel of heating system in agriculture, agricultural and forest biomass resources were surveyed, the pelletizer with capacity of $50\;kg{\cdot}h^{-1}$ was designed and manufactured and pellets were made by the pelletizer. High heating value, ash content, etc. of pellets made of agricultural and forest by-products were estimated. Straw of rice was the largest agricultural biomass in 2009 and the total amount of rice straw converted into energy of $299{\times}10^3$ TOE. And in 2009, amount of forest by-product converted into energy of $9,579{\times}10^3$ TOE. High heating values of pellets made of stem and seed of rape, stem of oat, rice straw and rice husk were 16,034, 16,026, 16,089, 15,650, $15,044\;kJ{\cdot}kg^{-1}$ respectively. High heating values of pellets made of agricultural by-products were average 83.6% compared to that of wood pellet. Average bulk density of pellets made of stem and seed of rape, stem of oat, rice straw and rice husk was $1,400\;kg{\cdot}m^{-3}$ ($1.4\;g{\cdot}cm^{-3}$). Ash contents of the pellets were 6.6, 7, 6.2, 5.5, 33% respectively. Rice husk pellet produced the largest ash content compared to other kinds of pellets.

• Journal of Biosystems Engineering
• /
• v.35 no.1
• /
• pp.37-45
• /
• 2010

Since SRC (Short-term Rotation Coppice) such as poplar and willow can be harvested in three years, they are known to be a potential forest biomass as fuel for a power plant. The production system including transplanting and harvesting is, however, necessary to be mechanized because such a biomass should be handled in a massive volumetric size. A pull-type stem-cutting transplanter was developed in the research as the first step to realize the production of SRC. A needle-like transplanting device pushes a stem-cutting into the prepared soil bed by a pneumatic cylinder, and another device firms soil around a stem-cutting transplanted. Since this is an intermittent operation, it was necessary to develop a zero horizontal velocity mechanism which enabled only the transplanting needle part to continue a zero horizontal movement relative to the ground during the transplanting operation even when the tractor kept moving forward. The 2-row transplanter can transplant stem-cuttings at the rate of 6.5 seconds per row without missing a single attempt. The planting depth and distance were well maintained and controlled. Their CVs were between 2.1~3.4% and 0.87~1.7% for the depth and the distance, respectively. Although, the transplanted stem-cuttings tended to lean outward from the back-view and forward from the side view, they were planted within the range of $3^{\circ}$ from the upright position.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2012.05a
• /
• pp.71.2-71.2
• /
• 2012

There are rising demands for developing more efficient energy materials to stem the depletion of fossil fuels, which have prompted significant research efforts on proton exchange fuel cells (PEFCs) and lithium ion batteries (LIBs). To date, both PEFCs and LIBs are being widely developed to power small electronics, however, their utilization to medium-large sized electric power resources such as vehicle and stationary energy storage systems still appears distant. These technologies increasingly rely upon polymer electrolyte membranes (PEMs) that transport ions from the anode to the cathode to balance the flow of electrons in an external circuit, and therefore play a central role in determining the efficiency of the devices; as ion transport is a kinetic bottleneck compared to electrical conductivity, enormous efforts have been devoted to improving the transport properties of PEMs. In present study, we carried out an in-depth analysis of the morphology effects on transport properties of PEMs. How parameters such as self-assembled nanostructures, domain sizes, and domain orientations affect conductivities of PEMs will be presented.

• Journal of Korean Society of Forest Science
• /
• v.101 no.2
• /
• pp.244-250
• /
• 2012

The objective of this study was to analyze the above-ground biomass and crown fuel characteristics of Pinus densiflora stands in Yangyang, Gangwon province. A total of thirteen representative trees were destructively sampled in Yangyang region. The results showed that the stem density ($g{\cdot}cm^{-3}$) was 0.347~0.409, whereas the above-ground biomass expansion factors ranged from 1.251~1.419. In terms of crown fuel biomass, the above-ground biomass was $161.6Mg{\cdot}ha^{-1}$ while the stem biomass, branch biomass and needle biomass were $126.4Mg{\cdot}ha^{-1}$, $29.3Mg{\cdot}ha^{-1}$ and $5.9Mg{\cdot}ha^{-1}$, respectively. Needles and twigs with less than 1 cm diameter accounted 45.2% of the total crown fuel load. The available crown bulk density, which was calculated by dividing the crown fuel load to the crown volume, was $0.178kg{\cdot}m^{-3}$. The results of this study on the biomass and carbon stocks estimation of the Pinus densiflora together with the crown fire hazard assessment based on crown fuel loads are very significant information for the forest managers.