• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.4
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• pp.9-17
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• 1994

Effect of Newtonian and non-Newtonian oils on minimum ol film thickness in engine journal bearing were investigated at various oil viscosities. The influence of oil viscosity and engine operating conditions on minimum oil film thickness of main bearing and con-rod bearing was examined. Minimum oil film thickness for Newtonian oils increased uniformly with kinematic viscosity. But the correlation between kinematic viscosity and minimum oil film thickness was very poor for non-Newtonian oils. According to the straight-line regression analysis for non-Newtonian oils, high temperature high shear viscosity at 1 $1{\times}10^6Sec^{-1}$, $150^{\circ}C$ increase the coefficient of determination from 0.41 to 0.77. Con-rod bearing showed better correlation between minimum oil film thickness and engine operating conditions than main bearing.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.54-59
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• 2004

A measure for good products manufactured by grinding process is the surface roughness that is affected by a lot of operating parameters such as types of abrasive, grain size, bond material, wheel speed, table speed, depth of cut, hardness of workpiece and stiffness of grinding machine. In this study, an application of the design of experiments was tried for evaluating the effect of operating parameters on the surface roughness. The workpiece was a high speed tool steel(SKH51) and the surface grinding was conducted. In order to obtain the best surface roughness within constraints of the working range, the optimal grinding conditions were selected. The usefulness of this method was evaluated by the statistical strategy.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1183-1191
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• 2000

Operating conditions for reduction of membrane fouling in treatment of dissolved organic matter by UF membrane process were investigated by pilot-scale plant using various operating conditions. As inlet pressure increased, increament of transmembrane pressure and flux decline were faster. The reason was due to the increase in adsorption of dissolved organic matter and the development of cake layer compression on the membrane surface. When efficient pressure (the difference of pressure between backwash and transmembrane pressures) was high, small amount of pollutant was retained on the membrane surface. When backwash was frequently conducted, low concentration of pollutant was maintained in recycling water. Therefore, backwash could be efficiently conducted with high efficient pressure and high frequency. Fouling rate was correlated with backwash and inlet pressures, recovery rate and cumulative permeated volume. Among the operating parameters backwash pressure was most closely related to fouling rate and inlet pressure was next to backwash pressure. It seems that the fouling was strongly related to pressure which leads to the cake layer compression and adsorption of dissolved organic matter.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.04a
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• pp.145-147
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• 1999

• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1376-1386
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• 2016

This study investigated the loading rate effect on the fracture resistance under cyclic loading conditions to understand clearly the fracture behavior of piping materials under seismic conditions. J-R fracture toughness tests were conducted under monotonic and cyclic loading conditions at various displacement rates at room temperature and the operating temperature of nuclear power plants (i.e., $316^{\circ}C$). SA508 Gr.1a low-alloy steel and SA312 TP316 stainless steel piping materials were used for the tests. The fracture resistance under a reversible cyclic load was considerably lower than that under monotonic load regardless of test temperature, material, and loading rate. Under both cyclic and monotonic loading conditions, the fracture behavior of SA312 TP316 stainless steel was independent of the loading rate at both room temperature and $316^{\circ}C$. For SA508 Gr.1a lowalloy steel, the loading rate effect on the fracture behavior was appreciable at $316^{\circ}C$ under cyclic and monotonic loading conditions. However, the loading rate effect diminished when the cyclic load ratio of the load (R) was -1. Thus, it was recognized that the fracture behavior of piping materials, including seismic loading characteristics, can be evaluated when tested under a cyclic load of R = -1 at a quasistatic loading rate.

• Wind and Structures
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• v.32 no.5
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• pp.501-508
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• 2021

The turbine industry demands a reliable design with affordable cost. As technological advances begin to support turbines of huge sizes, and the increasing importance of wind turbines from day to day make design safety conditions more important. Wind turbines are exposed to environmental conditions that can affect their installation, durability, and operation. International Electrotechnical Commission (IEC) 61400-1 design load cases consist of analyses involving wind turbine operating conditions. This design load cases (DLC) is important for determining fatigue loads (i.e., forces and moments) that occur as a result of expected conditions throughout the life of the machine. With the help of FAST (Fatigue, Aerodynamics, Structures, and Turbulence), an open source software, the NREL 5MW land base wind turbine model was used. IEC 61400-1 wind turbine design standard procedures assessed turbine behavior and fatigue damage to the tower base of dynamic loads in different design conditions. Real characteristic wind speed distribution and multi-directional effect specific to the site were taken into consideration. The effect of these conditions on the economic service life of the turbine has been studied.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.4
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• pp.92-102
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• 2001

The effect of ethanol-blending on the performances of the MPI gasoline engine was examined. The experiments were carried out for the stoichiometric conditions under MBT spark timing over various operating conditions. The blending rate of ethanol were determined as 10 to 30 percent according to the analysis of the properties of blended fuels. The engine with ethanol-blended fuels showed improved performances such as brake torque, brake power, brake thermal efficiency and exhaust emissions compared with those of pure gasoline over most operating conditions. Though the brake specific fuel consumption was increased by ethanol-blending due to their lower heating values, the increasing rates of the brake specific fuel consumption were limited to the half of the blending rates owing to the increase in the thermal efficiency.

• Journal of Energy Engineering
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• v.22 no.2
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• pp.205-210
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• 2013

Cycle-to-cycle variation has long been recognized as limiting the range of operating conditions of spark ignition engines, in particular, under lean and highly diluted operation conditions. At a part load, some of the cycles tend to knock, while others may have incomplete combustion by the time the exhaust valve opens. An experimental study has been performed in order to evaluate the relative contribution of several relevant parameters on the cyclic variability in spark ignition engines. In general, the stability of engine operation is improved with fuel injector according to the optimal injection timing, but the stability of engine operation at idle is not improved compared with a practical gasoline engine. In this study, we investigated the relationship of the effect of operating conditions for the stability at low speed and load.

• Journal of the military operations research society of Korea
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• v.23 no.1
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• pp.76-87
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• 1997

This paper deals with reliability and MTTF analysis of a non-repairable man-machine system operating under different weather conditions. The system consists of a hardware(machine) and a two-operator standby subsystem such as the air combat maneuvering of fighters with dual seat. The failure times for the subsystems follow the exponential distribution with constant parameter. By considering not only the effect on hardware component but also the weather conditions and human performance factors such as the operator's errors, a Markov model is presented as a method for evaluating the system reliability of time continuous operation tasks. Laplace transforms of the various state probabilities have been derived and then reliability of the system, at any time t, has been computed by inversion process. MTTF has also been computed.

• Journal of Biosystems Engineering
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• v.30 no.3 s.110
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• pp.166-171
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• 2005

A prototype peeling device with rotating cutter blades was designed to peel altari radish skin. With the designed blades, the maximum peeling depth increased as the cutter clearance increased but the effect of the peeling speed was not significant. The optimal operating conditions for peeling was; the peeling speed was at 0.19m/s when peeled 2.5 blades/sec and the maximum peeling depth was 1.5mm, the minimum peeling depth was 0.5mm, and the leaf rotating speed was 12 rpm, respectively. In the peeling test fur the optimum operation conditions, with a auxiliary rolling device could adjust the rotational speed of the root uniformly, the altari radishes under 70mm diameter were peeled perfectly.