• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.942-945
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• 2002

A garter spring, which is a long. special, close-coiled extension spring with its ends joined to form a ring, is used in connection between vacuum circuit breaker and bus bar in switchgear. To carry short-time current and resist welding at the contact surface in the connection, the garter spring must transmits an uniform contact force to the contact surface through the contact chips arranged in the circumference of bus bar. In this paper, the system for measurement of the contact force by the garter spring is developed. Using the developed measurement system, the design of the connection structure including the garter spring is reviewed to obtain the uniform contact forces in all of contact chips.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.2
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• pp.187-192
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• 2009

A snap ring is a kind of metal spring with open ends which can be installed into a groove to prevent lateral movement. In this study a nonlinear finite element analysis model is developed to simulate the fastening process of a snap ring connecting the constant velocity joint and the transmission. Insert load, disengage load and breakage are three important issues. They are analyzed using the developed model. The load histories of simulations are similar to those of tests and the differences of maximum load are around 10%. Bending of the entire ring and unfolding of the end section are major contributors of the fastening load. The load variations caused by the angular position of spline tooth are about 50%. Breakage is highly sensitive to the position of a snap ring.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.242-245
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• 2003

A garter spring, which is a long, special, close-coiled extension spring with its ends joined to form a ring, is used in tulip contactor between vacuum circuit breaker and bus bar in switchgear. To carry short-time current and resist welding at the contact surface in the tulip contactor, the garter spring must transmits an uniform contact force to the contact surface through the contact chips arranged in the circumference of bus bar. In this paper, the system for measurement of the contact force by the garter spring is developed. Using the developed measurement system, the design of the connection structure including the garter spring is reviewed to obtain the uniform contact forces in all of contact chips.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.387-394
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• 2000

Theoretical and experimental study is conducted on the contact pressure distribution of a radial tire in motion under various camber angles. Tire construction is modelled by a spring bedded elastic ring, consisted of sidewall springs and a composite belt ring. The contact area is assumed to be a trapezoidal shape varying with camber angles and weighted load. The basic equation in a quasi-static form is derived for the deformation of a running belt with a constant velocity by the aid of Lagrange-Euler transformation. Galerkin's method and stepwise calculation are applied for solving the basic equation and the mechanical boundary condition along both sides of the contact belt part subjected to shearing forces transmitted from the sidewall spring. Experimental results on the contact pressure, measured by pressure sensors embedded in the surface of the drum tester, correspond well with the calculated ones for the test tire under various camber angles, running velocities and weighted loads. These results indicate that a buckling phenomenon of the contact belt in the widthwise direction occurs due to the effect of camber angle.

• Journal of the Korea Society for Simulation
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• v.32 no.4
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• pp.1-10
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• 2023

This study examines the response when the shock by underwater explosion is transmitted to a vertical launch air-vehicle mounted on a ship using modeling and simulation, and is about a plan to increase method shock resistance to protect the air vehicle. In order to obtain an accurate mathematical model, a dynamic characteristic test was performed on similar equipment, and through this, the mathematical model could be supplemented. And, using the supplemented mathematical model, the air vehicle simulated the shock response by the underwater explosion specified in the BV043 standard. As a result of the first simulation, it was confirmed that air vehicle could not withstand shock, and air vehicle protection method using a ring spring type shock absorber was studied. In addition to the basic shape of abosber, it was confirmed that the ring spring absober can be used to increase the impact resistance of a shipborn vertical launch vehicle by performing simulations for each case by changing deseign varables.

• Tribology and Lubricants
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• v.12 no.4
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• pp.7-12
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• 1996

Present study was undertaken to investigate the leakage and friction of self-lubricating piston seal rings. A crank-piston type gas leakage test set-up was constructed. The piston rings were made of PTFE-polyimide composite. The free gap configurations of the seal rings were butt and step types. Eccentric tension rings were used to give the seal rings prepressure between the seal rings and cylinder wall. Two sizes of the tension rings were installed to investigate their effect on the gas leakage and friction of the seal rings. The results showed that step type seal rings are superior than the butt types. High tension spring rings resulted in low leakage and high friction loss. In order to reduce the gas leakage and friction loss of the piston seal rings, there should be compromise between the number of ring stages and prepressure of the tension rings.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.190-195
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• 1998

This paper reports on the theoretical and expetimental study of the vane and cam ring motions in a variable displacement vane pump which is already used widely in various industrial and automotive applications. Dynamic equations of vane and cam ring motion and flow continuity equations are derived and then solved simultaneously using the numerical method. Vane detachment cause the pressure tipples, noise, wear in cam ring, and decrease the volumetric efficiency. Consequently, Vane detachment occurs due to excess compression in the pumping chamber, and it can be reduced by adjustment of design parmeters.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.3
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• pp.36-45
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• 2010

To analyze the relationship between climatic factors (monthly mean temperature and total precipitation) and tree-ring growths of Quercus mongolica Fischer (Mongolian oak) with different topographic sites in Mt. Worak, more than 10 trees were selected from each of seven stands. Two cores from each tree were measured for ring width. After crossdating, each ring-width series was double standardized by fitting first a negative exponential or straight regression line and secondly a 60-year cubic spline. Seven stands were categorized in two groups using cluster analysis for tree-ring index patterns. Cluster I (four stands) was located in higher elevation (550-812 m) with aspects of east, west and northwest, and cluster II (three stands) was located in rather lower election (330-628 m) with aspects of north and northwest. The aspects of two clusters were not significantly different. Response-function analysis showed a significant positive response to March precipitation for both clusters. It indicates that moisture supply during early spring season is important to radial growth because the cambial growths of ring-porous species, such as Mongolian oak, start before leaf growth. Cluster II showed a positive response to the precipitation of middle and late growing season, too.

• Journal of the Korean Wood Science and Technology
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• v.50 no.2
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• pp.81-92
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• 2022

To analyze the relationship between climatic factors (mean monthly temperature and total precipitation) and tree-ring growths of Pinus densiflora S. et Z. from National Parks (according to region) of the Korea, 20 trees were sampled from 13 National Parks. Only trees that were successfully cross-dated were used for dendrochronological analysis, and at least 11 trees were included. The tree-ring chronology of Mt. Bukhan (covering the shortest period of 1917 - 2016 [100 years]) was assessed, as well as that of Mt. Seorak (covering the longest period of 1687 - 2017 [331 years]). After cross-dating, each ring width series was double-standardized by first fitting a logarithmic curve and then a 50-year cubic spline. The relationships between climate and tree-ring growth were calculated with response function analysis. The results show a significant positive correlation between a given year's February-March temperature, May precipitation levels, and tree-ring growth. It indicates that a higher temperature in early spring and precipitation before cambium activity are important for radial growths of Pinus densiflora in the Korea.

• Journal of Conservation Science
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• v.38 no.2
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• pp.87-95
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• 2022

This aimed to species identification and tree-ring dating of wooden elements used in the Myeongjeong-gate of the Changgyeong-palace, Seoul, Korea. Of the 79 wooden elements evaluated, 78 were confirmed to be hard pines and one belonged to Abies spp.. Cores of the wooden elements were collected using a drill for tree-ring dating, and ring-width plots of individual samples were constructed using the TSAP software. The tree-ring dating results for the outermost ring of 58 hard pine wooden elements revealed the following felling dates: early spring of 1604-late fall of 1615, late fall of 1706-early spring of 1707, and late fall of 1828-late fall of 1834. The obtained felling dates of the 1600s and 1800s were found to be consistent with those in the construction and repair records of the Annals of Joseon Dynasty, Gwanghaegun's Diary and Changgyeonggung Yeonggeondogam Uigwe. However, the obtained felling dates of the 1700s were not consistent with those in the construction and repair records. Therefore, additional confirmation of repairs that were not included in the records was possible using tree-ring dating.