• International Journal of Precision Engineering and Manufacturing
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• v.7 no.4
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• pp.23-27
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• 2006

Rubber is used in many industrial products, such as hoses, rubber belts, and oil seals. In particular, more than 200 rubber parts are used in automobiles. The design technology of these parts is largely dependent on field experience, which leads to lengthy and expensive developing procedures. However, with the help of recent developments in nonlinear computer analysis, new rubber products can be developed at low cost. In this study, rubber injection molding design variables, such as location and number of gates, were optimized using computer-aided engineering with the cross-WLF equation to produce CLIP rubber products made from ethylene propylene diene monomer(EPDM). The validity of the proposed design was evaluated by comparison with actual forming results.

• International Journal of Automotive Technology
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• v.7 no.2
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• pp.121-128
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• 2006

The interaction between adherent molecules and gas molecules was modeled in the molecular scale and simulated by the molecular dynamics method in order to understand evaporation and removal processes of adherent molecules on metallic surface using high temperature gas flow. Methanol molecules were chosen as adherent molecules to investigate effects of adhesion quantity and gas molecular collisions because the industrial oil has too complex structures of fatty acid. Effects of adherent quantity, gas temperature, surface temperature and adhesion strength for the evaporation rate of adherent molecules and the molecular removal mechanism were investigated and discussed in the present study. Evaporation and removal rates of adherent molecules from metallic surface calculated by the molecular dynamics method showed the similar dependence on the surface temperature shown in the experimental results.

• Ocean and Polar Research
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• v.29 no.4
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• pp.311-316
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• 2007

Ocean noise may be used for monitoring wind speed and rainfall rate on the sea surface, as well as for tracking whales' migration routes. In particular, low-frequency ocean noise has recently been of concern with relation to the behavior of marine mammals. Low-frequency ocean noise has been increasing over the past few decades due to increase of ship traffic and offshore oil industry activities. Mechanical noise such as flow noise and cable strumming noise may be induced if low-frequency ocean noise is measured by cabled traditional hydrophone in high current areas. To successfully measure low-frequency ocean noise in a shallow water environment with strong current, we developed a self-recording hydrophone. This paper describes the main configurations of the self-recording hydrophone and presents some results on measured data.

• 유공압시스템학회:학술대회논문집
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• 2010.06a
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• pp.25-32
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• 2010

A geortor type pump is widely used in lubrication and actuator systems. Especially the pump is an essential machine element of an automotive engine to feed lubrication oil and power source of automatic transmission. A gerotor is a planar mechanism consist of a pair of rotor and circular tooth of stator assembly which forms a closed space. However, related industries do not have necessary technology to design and optimize the pump and paid royalties of gerotor profile on an advanced company. Also, gerotor profiles with setting design parameter have not been sufficiently analyzed from a theoretical view. Therefore, it is very difficult for designer to decide the specifications of the gerotor profiles, and calculation and fluctuation of flow rate is not yet confirmed. In this study, theoretical analyses and optimal design of the gerotor profiles have been performed numerical method by mathematical base. An automated design system of the tooth profile has been developed through MATLAB GUI Program considering various design parameters.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.3
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• pp.166-176
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• 2003

Experiments have been conducted in order to make comparisons of a alternative refrigerant (R-410A) cycle characteristic with an existing refrigerant (R-22) cycle characteristic in terms of cooling capacity and coefficient of performance (COP). The parameters examined in the present work include air flow rate, indoor/outdoor air temperatures, and indoor relative humidity. These two refrigeration cycles share all components except compressor, accumulator, oil separator, and piping connecting them. The measurements were made using an air-enthalpy calorimeter. The experimental results show that the R-410A cycle has many advantages over indoor conditions while the R-22 cycle has better performance over outdoor conditions.

• Journal of the Korean Professional Engineers Association
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• v.15 no.1
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• pp.32-35
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• 1982

The sudden shock of repeated oil crisis and the subsequent violent increases in petroleum prices have given rise to an intensive worldwide effort to develop alternate sources of clean energy. Against this background, a great deal of attention has recently come to be focused on mini-scale hydroelectric power turbine generation. There is now a strong demand for the development of a hydroelectric generator suitable for generating power on a small scale and copable of overcoming the high per kilowatt cost of conventional one's then Francis turbine. Hence was accordingly developed the "Cross flowturbine generator" of 1000kw and less, which we call. This mimi-scale water turbine is reliably and easily handled and also can be economicaly manufactored in a range with effective head of over 3meter's a flow rate of minimum 30 liter per sec and an output of below 1000kw good's.kw good's.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.12a
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• pp.58-58
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• 2020

Xanthoceras sorbifolium Bunge (yellowhorn) is a woody tree in the soapberry family, Sapindaceae, native to northern China. This species has been identified as a major woody bioenergy plant for bio-diesel production because of high oil content in seed. But the flowers do not bear fruit well while the many flowers blooming. This study was performed to regenerate in vitro plantlet using adventitious shoot formation. To establish the protocol of plant regeneration, adventitious shoots formation rate in the culture of cotyledon of immature zygotic embryos was 68.6% in 1/2 MS medium with 0.5 mg l-1 BA and 3% sucrose (w/v). In the culture of cotyledons of mature zygotic embryos, induction of adventitious shoots was needed to contain high sucrose in pre-culture medium and the frequency of shoot induction was 64.4%. Multiple shoots were induced in 0.5 mg l-1 TDZ, and rooting of shoot was induced 4.0 mg l-1 IBA. Flow cytometry analysis revealed that all the regenerated plantlets were diploid.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.149-162
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• 2010

The most serious problem in oil stockpiles with artificial underground cavern is maintaining the stability of ground water system. In order to understand the ground water system around K-1 site, we determined the regional flow direction and level distribution of groundwater, and investigated the major geologic factors influencing their flow system. Reactivated surface along the contact between granite and gneiss, and fractures and faults along the long acidic dyke may contribute as important pathways for groundwater flow. Within K-1 site, groundwater level fluctuation is closely related to the rainfall events and injection from surface or influx water. In this project, the effect of groundwater pumping from the southern wells was examined. Based on equations relating water level drawdown to pumping rate at those wells, their pumped outflow of groundwater ranged from $80\;m^3$/day to less than $250\;m^3$/day. The modeling results with MODFLOW imply that the previous groundwater pumping at distance of 1.2 km may not affect the groundwater level variations of the K-1 site. However, continuous pumping work at quantity over $250\;m^3$/day in this area will be able to affect the groundwater system of the K-1 site, particularly along the acidic dyke.

• Korea-Australia Rheology Journal
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• v.21 no.4
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• pp.269-280
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• 2009

The drop formation dynamics of a shear thinning, elastic, yield stress ($\tau_o$) fluid (Carbopol 980 (poly(acrylic acid)) dispersions) in silicone oil has been investigated in a flow-focusing microfluidic channel. The rheological character of each solution investigated varied from Netwonian-like through to highly non-Newtonian and was varied by changing the degree of neutralization along the poly (acrylic acid) backbone. We have observed that the drop size of these non-Newtonian fluids (regardless of the degree of neutralisation) showed bimodal behaviour. At first we observed increases in drop size with increasing viscosity ratio (viscosity ratio=viscosity of dispersed phase (DP)/viscosity of continuous phase (CP)) at low flowrates of the continuous phases, and thereafter, decreasing drop sizes as the flow rate of the CP increases past a critical value. Only at the onset of pinching and during the high extensional deformation during pinch-off of a drop are any differences in the non-Newtonian characteristics of these fluids, that is extents of shear thinning, elasticity and yield stress ($\tau_o$), apparent. Changes in these break-off dynamics resulted in the observed differences in the number and size distribution of secondary drops during pinch-off for both fluid classes, Newtonian-like and non-Newtonian fluids. In the case of the Newtonian-like drops, a secondary drop was generated by the onset of necking and breakup at both ends of the filament, akin to end-pinching behavior. This pinch-off behavior was observed to be unaffected by changes in viscosity ratio, over the range explored. Meanwhile, in the case of the non-Newtonian solutions, discrete differences in behaviour were observed, believed to be attributable to each of the non-Newtonian properties of shear thinning, elasticity and yield stress. The presence of a yield stress ($\tau_o$), when coupled with slow flow rates or low viscosities of the CP, reduced the drop size compared to the Newtonian-like Carbopol dispersions of much lower viscosity. The presence of shear thinning resulted in a rapid necking event post onset, a decrease in primary droplet size and, in some cases, an increase in the rate of drop production. The presence of elasticity during the extensional flow imposed by the necking event allowed for the extended maintenance of the filament, as observed previously for dilute solutions of linear polymers during drop break-up.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.1
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• pp.73-84
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• 2003

A transient analysis on fuel temperatures in an aircraft was studied using the finite difference method. Numerical calculation was performed by an explicit method of modified Dufort-Frankel scheme. Among various missions, close air support mission was considered with 20% hot day ambient condition in subsonic region. The aircraft was assumed to be in turbulent flow. The fuel system model with additional fuel supplies and return concept was considered. As a result of this analysis, the fuel tank temperatures have increased with the increase of the additional fuel supplies. In contrast to tank temperatures, the fuel temperature at the engine inlet has decreased with the increase of additional fuel supplies except in some in-flight phases having high engine fuel flow. From this analysis, the fuel system with the additional fuel supplies and return concept has been shown to be an effective method to decrease the engine inlet fuel temperature. Also, it has been shown that fuel flow rate through fuel/oil heat exchanger is a key factor influencing fuel temperature.