• Tribology and Lubricants
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• v.19 no.3
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• pp.151-158
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• 2003

In metal cutting at the tool-chip interface, friction generates considerable amount of heat. Thus, the knowledge of wear properties of cutting tool material in high temperature has been as one of important factors in need of clarification. The authors presented the wear properties of 5%Co-5%V-1%Nb high speed steel, fabricated by powder metallurgy, in room temperature in previous articles. The objective of this paper is to clarify the effects of temperature on its wear properties. Wear tests in sliding conditions under various temperatures have been conducted using the pin-on-disc type wear test machine. The results indicate that the wear properties of 5%Co-5%V-1%Nb high speed steel in high temperature as well as in room temperature are excellent. It may be deduced that the oxide layer formed on worn surface at high temperature is stable enough to prevent wear due to the high temperature strength of its matrix.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.201-210
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• 2000

The noncontacting groove end face seal is one of various approaches to sealing gases with a single seal. Gas pumped into groove maintains operating gap and lubricates between primary ring and mating ring. So it removes heat and decreases face wear. In this paper, K-type and T-type grooved seals have been analyzed numerically using the finite element method. It explains the effects of groove shapes in gas seals along rotating speeds with a temperature gradient, face distortion, stress and so on. The calculated FEM results show the operating gap and rotating speed are strongly related to the leakages of a gas seal and that T-type groove seal shows a good thermal performance compared to K-type groove seal.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.986-993
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• 2011

The role of brake is safely to transport passenger & cargo and stop vehicles at emergency in railway vehicle. Brake system reduces the speed by control command of electricity or air. mechanical methods to perform brake are disk brake & tread brake. This study targeted development of highly efficient sintered alloy brake shoe in railway vehicle whose high frictional coefficient, wear resistance, compatibility of the existing tread brake shoe & minimization of wheel's thermal damage and performed development of friction material's formulation, analysis of pressure distribution in wheel tread & brake shoe, optimum form design through analysis of heat flow.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.4
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• pp.297-304
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• 1989

Development of a more satisfactory program of computing the performance on a multi-tube evaporator with continuous plate fins is attempted in this study. The fluid flow involving a change of phase make the flow properties and fluid friction factor of refrigerants, the heat transfer coefficients of refrigerant and air sides vary significantly. Taking such variations into account, a useful program is developed to predict the steady state performance of a multi-tube evaporator. The program was applied to an evaporator which has outside diameter of 10.05mm, inside diameter of 9.35mm, length of 5.4m and two rows arraied staggered. Then the variations of refrigerant quality, temperature, pressure, velocity, enthalpy, specific volume and air temperature, tube temperature were discussed. Satisfactory results were presented that the degree of superheat at the outlet side was $4.4^{\circ}C$ and the air temperature drop between the inlet and outlet of the air conditioner was $10^{\circ}C$.

• Journal of Aerospace System Engineering
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• v.4 no.2
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• pp.16-20
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• 2010

In General, the hydraulic system of T-50 Advanced Trainer is applied to flight control system, wheel & Brake system and fuel system for aircraft operation. The hydraulic system is operation with pressure of 3000psi. and many mechanical parts which is operated by hydraulic system has been stressed in incomplete environment same as heat and friction. for example, Oil leakage had occurred in the shutoff valve of FFP used in a certain period of time. After study, The crack progressed by fatigue due to the irregular hydraulic pressure and vibration has been identified as the reason of oil leakage. This paper presents life cycle extension plans of FFP shutoff valve by configuration improvements of shutoff valve and FFP hydraulic motor.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.25-29
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• 2008

In automotive disc brake system, friction heat is not uniformly distributed due to various reasons such as thermal expansion and imperfections in geometry. It is well known that thermoelastic distortion due to fictional heating affects the contact pressure distribution and can lead to thermoelastic instability, where the contact load is concentrated in one or more small regions on the brake disc surface. These regions then take very high temperatures and passage of hot spots moving under the brake pads can cause low frequency vibration called brake judder. This paper presents the FEM(finite element method) result for the temperature distribution of ventilated disc brake. A steady state two-dimensional model of disc brake system predicts the surface temperatures during a multi-stop driving schedule.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.5
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• pp.1037-1049
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• 2001

Considerable interest has evolved in the flow of non-Newtonian fluids in channels of noncircular cross section in compact heat exchanges. Analytical solution was developed for prediction of the flow rate and maximum velocity in steady laminar flow of any incompressible, time-independent non-Newtonian fluids in straight closed and open channels of arbitrary, but axially unchanging cross section. The geometric parameters and function of shear describing the behavior of the fluid model were evaluated for fluid flow among a bundle of rods arranged in triangular and square array. Numerical values of dimensionless maximum velocities, mean velocities, pressure-drop-flow parameters and friction factors were evaluated as a function of porosity and pitch-to-radius ratio.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.528-535
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• 2002

In order to achieve high precision machine tools, the research for performance enhancement of feed drive systems is required. Development of the high speed feed drive system has been a major issue for the past few decades in machine tool industries. The reduction of the tool change time as well as rapid travel time can enhance the productivity. However, the high speed feed drive system generates more heat in nature, which leads thermal expansion that has adverse effects on the accuracy of machined parts. Stick-slip friction has a great influence on the contouring accuracy of CNC machine tools. In this paper table levitation system has been developed for the stick-slip in a feed drive systems. And also, the driving position is set near the center of the main slideway. From the results, it is confirmed that yaw error and straightness can be improved.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.206-208
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• 2002

Metalworking fluids (MWFs) are fluids used during machining and grinding to prolong the life of the tool , carry away debris, and protect the surfaces of work pieces. These fluids reduce friction between the cutting tool and the work surface, reduce wear and galling, Protect surface characteristics, reduce surface adhesion or welding and carry away generated heat. Workers can be exposed to MWFs by inhaling aerosols (mists) and by skin contact with the fluid. Skin contact occurs by dipping the hands into the fluid, splashes, or handling workpieces coated with the fluids. The amount of mist generated (and the result ins level of exposure) depends on many factors. To reduce the potential health risks associated with occupational exposures to MWFs, it is required to establish optimum MWFs supply method and condition with minimum Quantity in all over the mechanical machining field including high speed type heavy cult ing process.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.3
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• pp.32-37
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• 2002

In this paper soybean flour to weak heat the soybean pulverizing is a nutritive qualities on the demolition by friction fever. in the soybean moisture and protein albumen, it is get tangled the present of soybean to pulverizing of the hesitate to do difficult. full fat activated soybean flour is the same as lipoxygenase a low temperature by handling to ferment of the not demolition is not method. electron wave the drying soybean with far-infrared to using soybean powder of good powder manufacturing method of development industry a people to health contribution