• Proceedings of the KSME Conference
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• 2004.04a
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• pp.531-536
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• 2004

In-arm type hydropeumatic suspension unit(ISU) is an equipment of armed tracked vehicle to absorb impact load and vibration from the irregular ground. During the operation of ISU, main piston moves forward and backward and oil flowing through damper transmits the external impact load to floating piston. Heat is generated in ISU by the oil pressure drop through the damper orifice and the friction between cylinder wall and two pistons. On the other hand, internal heat dissipatis outside via heat convection. Occurrence of high temperature can deteriorate durability of major components and basic function of ISU. And, it can cause fatal problem in the ISU life time and the sealing performance of piston rings. As well, the spring constant change of nitrogen gas that is caused by the temperature rise exerts the negative effect to the vehicle stability. Therefore, in this paper, we analyze the heat transfer analysis of the entire ISU unit, by finite element method, with the outside flow velocities 8m/s and 10m/s.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.8
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• pp.812-818
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• 2009

A MOV(Main Oxidizer shutoff Valve) controls the flow rate of liquid oxygen into the rocket combustor by opening and shutting operations piloted by a pneumatic force. In order to improve the effective design for sealing parts of poppet and piston assemblies, the poppet assembly has been designed to be just contacted with the piston assembly. However, to avoid a gap at the poppet/piston contact surface and to evaluate the MOV operating performance, an analyze on the force balance during the closing motion have been performed. For the accuracy of the analysis, the friction forces and the hydraulic forces have been respectively obtained by experiments and CFD analysis. Through the analysis, some important design parameters such as the spring constant, poppet friction and orifice size in the force balance have been introduced and the required operation performance of the MOV has been proved feasible.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.5
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• pp.7-13
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• 2010

Main starting valve is one of the main parts in the control system of diesel engines, purposed for starting main engines. It is composed of ball valve, check valve, actuator, etc. The design axioms provide a general framework for design methodology. Two axioms are independence axiom and information axiom. These axioms can be applied to all design process in a general way. The first axiom is introduced to analyze and evaluate the design of a main starting valve. The design parameters(DPS) are determined sequentially by considering the independence axiom. For the structural design of a main starting valve, the strength is calculated by using finite element method. In addition, the strength of its actuator piston is evaluated.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.56-61
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• 2020

Fuel economy has always been a major issue in the automobile industry, especially owing to the associated environmental concerns. It is widely known that only 5-20% of the energy generated by automobiles running on internal combustion engine engines is used as power, while the rest is consumed because of friction between components. The main components of the reciprocating piston type compressor used in vehicles, such as the shaft, swash plate, piston, and cylinder, cause severe energy loss owing to frictional contact between each other. The wear contact between the main shaft and the other components is particularly severe. Most quality issues arise owing to the sticking phenomenon that occurs between these parts. In this study, a coating solution to reduce friction is prepared by mixing adhesive solid lubricant, organic binder-polyadimide, inorganic binder (Binder), and graphite in four different ratios, and the best combination is determined.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.6
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• pp.167-177
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• 2003

In this study, a mathematical nonlinear dynamic model is introduced to predict the damping force of automotive shock absorber. And 11 design parameters were proposed for the sensitivity analysis of damping force. Design parameters consist of 5 piston valve design parameters, 5 body valve design parameters and 1 initial pressure of reservoir chamber air. All of these design parameters are main design parameters of shock absorber in the procedure of shock absorber design. The simulation results of this paper offer qualitative information of damping force variation according to variation of design parameters. Therefore, simulation results of this paper can be usefully use in the design procedure of shock absorber

• Journal of Power System Engineering
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• v.22 no.6
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• pp.80-86
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• 2018

A damper is a hydraulic device designed to absorb or eliminate shock impulses which is acting on the sprung mass of car body. It converts the kinetic energy of the shock into another form of energy, typically heat. The main mechanism for providing damping is by shearing the hydraulic fluid as it flows through restrictions. Since the damping mechanism depends on the flow restrictions, these restrictions are very important in damper design. Damper engineers often try several combinations of valve shims, piston orifices and bleed orifices before finding the best combination for a particular setup on a car. Therefore, the ability to tune a damper properly without testing is of great interest in damper design. For this reason, many previous researches have been done on modeling and simulation of the damper. This paper explains a genetic algorithm method to find the optimal parameters for the design objective and the simulation results agree well with the targeted damping characteristics.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.7
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• pp.105-113
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• 2022

In this study, a variable displacement swash plate pump supplying high-pressure hydraulic oil to control the hydraulic system of a marine engine was developed. A structural analysis was performed on the main parts of the pump to ensure the structural safety in the design. Using a pump testing equipment, performance characteristics such as no-load flow rate, load flow rate, flow rate according to the swivel angle change, flow rate with lubrication orifice, and response time according to the swivel motion were tested. Consequently, the pump was confirmed to satisfy the required specifications.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.4
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• pp.380-386
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• 2019

In this paper, in order to compare the mixing ratio according to the feeding method, the input error of the main material and the sub material was measured and analyzed for 100 cycles using raw material having the same viscosity. As a result of the piston pump method, the input error of main material and sub material varied greatly from 0g to 3g, and the maximum error ratio was 10.3%. In the dual-screw rotation method, the input error varied from 0.01g to 0,4g, and the maximum error ratio was 0.41%, and almost no input error occurred. As the process cycle increased, it was found that the feed was almost uniform. The dual-screw rotary two-component mixing system was used to measure and analyze the inputs of the main and sub materials for 100 using three types of liquid silicones with different viscosities of the raw materials. As a result, the average error was 0.75g and the error rate was less than 1% regardless of the viscosity of the applied raw materials. When rae materials having the same viscosity were used, the average error ratio of the piston pump method was 4.09%.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.10-13
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• 2010

The flow field in road tunnel is influenced by some facts such as piston effect of vehicle's move, operation of ventilation facilities, natural wind and buoyancy effect of fire plume. Among those, jet fan is one of main ventilation facilities especially in longitudinal ventilation system of tunnel. In this study to analyze tunnel flow induced by operation of jet fan, numerical simulation has been carried out. The velocity distributions and streamlines in tunnel are examined to consider the three-dimensional characteristics of tunnel flow caused by jet fan.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.4
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• pp.36-42
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• 1996

Analysis of heat transfer on small-size Diesel engine is required for the development of high performance and efficiency engine. This basic study aims to establish heat transfer technique for marine Diesel engine. The main results from this study are as follows : 1) Overall engine heat transfer correlation of Re-Nu. 2) Radiant heat flux as fraction of total heat flux over the load range of several different Diesel engine. 3) Characteristics of heating curves on piston, cylinder liner and head. 4) Surface heat flux versus injection timing.