• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.439-445
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• 2005

The tribological properties of ceramics are very important in the application to engineering ceramic parts such as seal rings, pump parts, meter parts, and so on. In this study, the effects of each other purity on the mechanical and tribological properties of alumina and zirconia ceramics were investigated. Sliding distance, sliding speed, contact load. friction coefficient, the amount of worn out material at a certain time, and the prepared composites were measured. Crystalline phases and microstructure were examined with XRD and SEM. We obtained the good properties of friction coefficient and wear resistance at the purity 99.7$\%$ of alumina. However, The purity 95$\%$ were great at the wear amount of worn out material.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.128-131
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• 2013

Energy losses through windows and doors are big problems in the construction industry. For glass only, it has takes the largest portion of mass from window assembly and it responsible for 24 ~ 45% of energy loss from total building energy loss. Insulating glass unit should maintain their basic functions during their working life in order to contribute positively for global warming issue. There have been many research works for improving insulating glass unit durability. But it is not easy job to fulfill the requirements because insulating glass units composed of many components. So, overall it is required to have right qualify control procedures starting from material selection to fabrication, shipping and installation to the customer site. In this report, we have reviewed the durability of insulating glass unit made from different grades of sealing materials based on globally accepted industry codes such as EN1279. ASTM E 2190 and Locally available code. KS L 2003. The result showed that there is a relationship between the mechanical properties of insulating glass 2nd sealant and the durability of the units.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.2
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• pp.241-248
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• 2013

In this study, bearings were developed for a high-power propulsion motor operating in inclined operation conditions through a simulation and similitude-experimental methods using commercial rotating machinery dynamics analysis software. The developed journal bearing is electrically insulated and has low thermal conductivity because each part is connected with 2-4 -mm-thick epoxy plates. To realize an appropriate oil thickness, an oil lift system is adopted, and a half separated structure is applied to ensure the feasibility of maintaining very heavy components. This study discusses some of the key design aspects of sleeve bearing design for high-torque and low-speed propulsion motor applications. Furthermore, the conditions of variable slope tests are examined to prevent oil leakage from the bearing lip seal on the test rig.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.1
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• pp.259-266
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• 1990

Leaks at the piston seal and the by-pass port of a small volume prover have relatively large influence on the proving accuracy in comparison with a conventional ball prover. The pulse interpolator, which is to increase the discrimination, is affected by the characteristic of the flowmeter signal. In this study, a small volume prover of the double cylinder type was designed in order to study the pulse interpolation error as well as the leak error. The basic volume of the prover determined by a water draw method was about 9.68L. Experimental results revealed that interpolation data attained by the repeated piston pass for turbine meters at a fixed flowrate may be treated effectively by applying a statistical method. It was possible to limit the pulse interpolation error less than .+-. 0.02% at the 95% confidence level. However, in the case of the bulk meter, if failed to achieve the required repeatability level because of the pulse characteristics. The basic volume change appeared to be independent of the piston velocity within the .+-. 0.05% of tolerance.

• Tribology and Lubricants
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• v.29 no.1
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• pp.13-18
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• 2013

Slider bearing is a widely used load-carrying element in the industry. While a large number of studies have investigated the effect of overall surface curvature, very few have considered sinusoidal surface. Recently, consideration of surface roughness/waviness or intentional wave design has been identified as an important issue in the manufacture of hard disk driver, mechanical seal, hydraulic machine, and etc. This study investigated the load-carrying capacity of a finite-width slider bearing with a wavy surface. Film thickness ratios, length-width ratio, ambient pressure, amplitude, and partial distribution were selected as the simulation parameters. The calculation results showed that the load-carrying capacity rapidly varied at small film thickness ratio, but the waviness near the area of minimum film thickness made much more influence with an increase in film thickness ratio. As the length-width ratio of bearing was increased, ambient pressure became more influential at small film thickness ratios. Furthermore a particular partial distribution of the wavy area led to higher load-carrying capacity than did the whole distribution. Consequently, the results of this study are expected to be of use in surface micro-machining of finite-width slider bearings.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.8
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• pp.743-750
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• 2016

Track rollers are the key parts that support the weight applied to the caterpillar track of construction machinery. The operating conditions of construction machinery are harsh; hence, the track rollers exposed to these conditions can experience failures such as oil leakage and breakdown of the machine, because of impacts during driving. The failure of track-rollers has a major effect on the operation of the construction machinery. Therefore, each manufacturer tries to evaluate the performance of their products by conducting a self-test. However, only the vertical loads applied to the track rollers are considered in most of the self-tests. This method has the problem of ignoring the horizontal loads that are applied to the track rollers while rotary driving, and hence it does not create the practical operating condition of the construction machinery. In this study, we have determined the experimental conditions that effectively consider the magnitudes of the vertical and horizontal loads. The results of simulations and experiments conducted to assess the influence of horizontal loads on the failure of track rollers are presented in this paper.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1613-1618
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• 2012

The wheel bearing is one of the important parts in a vehicle for translating power and bearing weight. When it is mounted on the knuckle by using bolts, the distortion of the outer ring including the seal mounting point and raceway occurs. In this study, a numerical analysis was performed to analyze the distortion of the outer ring by using a finite element method. The commercial software MSC.MARC was used for this purpose. Elastoplastic and contact analysis were carried out to compute the clamping behavior of the outer ring, bolts, and knuckle. Because the concavity on the flange of the outer ring affects the deformation, its effect was considered. To verify the reliability of this study, the roundness of the outer ring was measured. The experimental results were comparatively in agreement with the computational results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1083-1088
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• 2011

The effects of an impeller and floating ring seals on the performance of centrifugal pumps are investigated on the basis of their test results using water. The pumps are single-staged centrifugal pumps developed for 30-ton- and 75-ton-class liquid rocket engines, and are components of a turbopump that supplies propellants (liquid oxidizer and kerosene) to the combustion chamber. The exit width of the impellers and the numbers and exit angles of the impeller blades are found to have influences on the pump heads. In addition, the pumps have different efficiencies according to the gaps between the floating ring seals and the impellers, whereas the pump size seems to have less effect on the efficiency.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.1
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• pp.17-23
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• 2021

The membrane-type Liquefied Natural Gas (LNG) cargo tank is equipped with a double barrier to seal the LNG, of which the secondary barrier serves to prevent LNG leakage and mainly uses fiber-reinforced composite materials. However, the composite materials have thermal expansion anisotropy, which deteriorates shape distortion and mechanical performance due to repeated thermal loads caused by temperature changes between cryogenic and ambient during the unloading of LNG. Therefore, in this study, the longitudinal thermal expansion characteristics of the composite materials were obtained using a vertical thermo-mechanical analyzer, and the elastic modulus was obtained through the tensile test for each temperature to perform thermal load analysis for each direction. This is considered that it is useful to secure reliability from the viewpoint of the design of materials for a LNG cargo hold.

• Journal of the Korean Institute of Gas
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• v.26 no.6
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• pp.24-29
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• 2022

This paper is a purpose to Analyze and study the failure examples for a engine oil leakage of camshaft bearing seal, poor contact by computer connector fin damage and vaporizer inferiority on LPG automotive. The first example, when the researcher disassembled the cylinder head of engine to establish the cause for oil leakage, he confirmed the engine oil leakage by damaged between the engine intake camshaft bearing and seal part. The second example, the connector fin of power source line that control the starting of a car supplied with engine computer. As a result, it found the fact that the engine operation stopped because of cutting of the power source by connector fin damage. The third example, it verified the engine incongruity phe cutting of the power source by connector fin damage. The third example, it verified the engine incongruity phenomenon as thd gas didn't flow the vaporizer by foreign substance deposit. Finally, it supplied a small quantity gas from vaporizer to mix. As the computer controlling mix opening condition supplied a air as opening signal, the air and fuel became rarefied state. it knew that the engine didn't produce prpper power. Therefore, a car have to throughtly inspect not in order to arise the failure symptoms.