• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.982-989
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• 2009

Parallel Kinematic Mechanism (PKM) is a device to perform the various motion in three-dimensional space and it calls for six degree of freedom. For example, Parallel Kinematic Mechanism is applied to machine tools, medical equipments, MEMS, virtual reality devices and flight motion simulators. Recently, many companies have tried to develop new Parallel Kinematic Mechanism in order to improve the cycle time and the precisional tolerance. Parallel Kinematic Mechanism uses general universal joint and spherical joint, but such joints have accumulated tolerance problems. Therefore, it causes position control problem and dramatically life time reduction. This paper focused on the rolling element to improve sliding precision in new sliding ball joint development. Before the final design and production, it was confirmed that new sliding ball joint held a higher load and a good geometrical structure. FEM analysis showed a favorable agreement with tensile and compressive testing results by universal testing machine. In conclusions, a new sliding ball joint has been developed to solve a problem of accumulated tolerance and verified using tensile and compressive testing as well as FEM analysis.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.4
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• pp.50-55
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• 1998

Mould level control system for continuous casting process involves stick-slip friction in the sliding gate , time-delay, non-linearity, and certain uncertainties such as friction force variations between molten steel and the inner wall of mould. In this paper, sliding mode control technique was used to solve these complex control problem. The controller is then designed and implemented onto the continuous casting process. Testing result shows that sliding mode controller can decrease the fluctuating magnitude of the mould level and is superior to the existing PID controller.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.608-613
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• 1997

This study discusses the developmentof hydraulic rotary actuator design technology for industriol machinery and earthmoving equipment. The lubrication and wear analysis of sliding components of the machinery are very important parameters to sterngth the design technique. The analysis and were test are performed for the selected materials of the above mentioned coupled sliding members using the experimental results. One can selsct the better combination of sliding components.

• Tribology and Lubricants
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• v.9 no.1
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• pp.38-44
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• 1993

The present study was undertaken to investigate the dry wear characteristics of die steel STD 11 for cold molding. The wear test was experimentally carried out under different conditions using a wear device, which was made in laboratory, and in which annular surfaces of wear testing specimens wear rubbed in dry sliding condition with varying the sliding speed, contact pressure, and sliding distance. The wear loss by variation of sliding speed was much in 0.3 m/sec and less in higher speed range above its sliding speed according to formation of the boundary lubrication film. The critical sliding speed with maximum value of the specific wear rate switched over to lower speed side according. as contact pressure increased. The critical sliding distance was increased with decrease in oxidation reaction velocity. The depth below subsurface showing maximum hardness (Hv) came out at the position, $60 \mu m$, of the maximum shear stress due to strain hardening.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3404-3412
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• 1994

The present study was undertaken to investigate the dry wear process and wear mechanism of the alumina ceramics in the purity variation which are used for the mechanical seal, roll, liner and dies. The wear test was carried out under different experimental condition using the wear testing device and in which the annular surface rubbed on dry sliding condition various sliding speed, contact pressure and sliding distance. In case of alumina purity 95%, there was speed range which wear loss increased rapidly owing to enlargement of heat impact force and temperature rise of wear surface. According as the alumina purity increased, wear loss decreased but alumina purity 85% with much void and defect had the most wear loss than any other alumina purity. The friction coefficient of sliding initial stage of wear curves has a large value but according to increase of sliding distance, it decreased owing to drop of the shear strength of wear surfaces.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.540-547
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• 2001

This study has evaluated the wear behavior of PTA (Plasma Transferred Arc) Inconel 625 and Stellite 6 overlays on Nimonic 80A substrate. Nimonic 80A alloy was also included for comparison. In order to evaluate the wear performance, three-body abrasive wear test and pin-on-disk dry sliding wear test were performed. Microstructural development during the solidification of deposits is also discussed. Wear test results show that the wear rate of Stellite 6 deposit is lower than that of Inconel 625 deposit and Nimonic 80A. The sliding wear resistance of overlay deposits follows a similar trend to the abrasive wear resistance, but for Nimonic 80A. The main wear mechanisms were abrasive wear for Inconel 625 deposit, adhesive wear and delamination for Stellite 6 deposit in pin-on-disk dry sliding wear test and ploughing in three-body abrasive wear test. Cross sectional examinations of the worn surface of pin specimens after pin-on-disk dry sliding wear test implies that the plastic deformation near worn surface has occurred during the wear testing.

• 연구논문집
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• s.28
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• pp.101-110
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• 1998

This study discusses the developement of hydraulic rotary actuator design technology for industrial machinery and earthmoving equipment. The lubrication and wear analysis of sliding components of the machinery are very important parameters to strength the design technique. The analysis and wear test are performed for the selected materials of the above mentioned coupled sliding members. The can be used to select the better combinations of sliding components.

• Tribology and Lubricants
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• v.11 no.4
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• pp.13-20
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• 1995

The present study was undertaken to investigate the purity variation of the alumina ceramics on the water lubrication mechanism. The annular surface of wear testing specimens of the alumina ceramics with different alumina purity against STB2 was rubbed in the distilled water under various sliding speed, contact pressure and sliding distance. The friction coefficient decreased lowered with formation of corrosion products due to the tribochemical reation as the sliding speed and contact load was increased. With increased sliding speed, the lower purity of 85 percent contribute largely to even degree of the friction surface, even it have about $\mu$ of 0.3 degree by the influence of a pore and impurities SiO$_{2}$. The friction surface of ceramics protacted by oxide was transfer from STB2.

• Wind and Structures
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• v.38 no.3
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• pp.171-191
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• 2024

Wind Driven Rain (WDR) poses a significant threat to the building environment, especially in hurricane prone regions by causing interior and content damage during tropical storms and hurricanes. The damage due to rain intrusion depends on the total amount of water that enters the building; however, owing to the use of inadequate empirical methods, the amount of water intrusion is difficult to estimate accurately. Hence, the need to achieve full-scale testing capable of realistically simulating rain intrusion is widely recognized. This paper presents results of a full-scale experimental simulation at the NHERI Wall of Wind Experimental Facility (WOW EF) aimed at obtaining realistic rain characteristics as experienced by structures during tropical storms and hurricanes. A full-scale simulation of rain in strong winds would allow testing WDR intrusion through typical building components. A study of rain intrusion through a sliding glass door is presented, which accounted for the effects of multiple wind directions, test durations and wind speeds; configurations with and without shuttering systems were also considered. The study showed that significant levels of water intrusion can occur during conditions well below current design levels. The knowledge gained through this work may enhance risk modeling pertaining to loss estimates due to WDR intrusion in buildings, and it may help quantify the potential reduction of losses due to the additional protection from shuttering systems on sliding glass doors during winds.

• Journal of the Korean Society for Heat Treatment
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• v.11 no.3
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• pp.159-167
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• 1998

In this study, friction-wear test was carried out on the carburized layer depth of a mechanical structure steel SNCM carburized with RX and LPG for 7hrs at $930^{\circ}C$ and also the wear properties of wear loss, wear rate, coefficient of friction, friction force and friction temperature were investigated. The wear properties for carburized layer of SNCM were tested on dry condition at the room temperature by the thrust load of 49~245N range at sliding speed of 0.2m/sec and the sliding speed of 0.2~1.0m/sec range at thrust load of 98N. Wear loss on the depth of carburizing layer was increased with increasing of thrust load and sliding speed, and with decreasing of hardness. The condition of worn surfaces were showed mild wear at less than the thrust load of 98N and sliding speed of 0.6m/sec but were showed severe wear at more than 98N and 0.6m/sec. The friction load and temperature were increased with increasing of thrust load but with increasing sliding speed was appeared minimum at 0.6m/sec. With increasing thrust load the wear rate was increased and the coefficient of friction was decreased, but with increasing sliding speed the wear rate and the coefficient of friction were decreased in 0.2~0.6m/sec and increased in 0.6~1.0m/sec, therefore 0.6m/sec in this testing is a transition velocity.