• Journal of Drive and Control
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• v.9 no.2
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• pp.8-14
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• 2012

Electro-hydraulic spring return actuator(ESRA) is utilized for air conditioning facilities in a nuclear power plant. It features self-contained, hydraulic power that is integrally coupled to a single acting hydraulic cylinder and provides efficient and precise linear control of valves as well as return of the actuator to the de-energized position upon loss of power. In this paper, the algebraic equations of ESRA at steady-state have been developed for the analysis of static characteristics that includes control pressure and valve displacement of pressure reducing valve, flow force on flapper as well as its displacement over the entire operating range. Also, the effect of external load on piston deviation is investigated in terms of linear system analysis. The results of static characteristics show the unique feature of force balance mechanism and can be applied to the stable self-controlled mechanical system design of ESAR.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.3
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• pp.74-81
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• 1996

The wave washer springs are widely used in non-return valves of fluid, especially in air check valves to confirm the rapid shut-off of valve propers. The stiffness of wave washer springs used in suction and exhaust valves of reciprocating air compressor play an important role on efficiency of the compressor. If the stiffness of the spring is too high, the pressure differences necessary to open the valves become high and the volumetric efficiency of cylinder decreasse. If the stiffness of the spring too low, the valve can not be closed rapidly and the inverse flow of air can take place. So, the optimum stiffness of valve spring is very important and it will be very helpful that the stiffness of wave washer springs to be used in suction and exhaust valves can be calculated in design stage of air compressor. In this paper the formula for calculating the spring constant of wave washer spring is introduced using bending and torsion theory of frames. The experiments are also carried out to measure the spring constants of several samples. It is proven that the calculated spring constants of wave washer springs are coincided well with measured values and that the formula presented in this paper for calculating the spring constants of wave washer spring is very useful for design of valves used in reciprocating air compressor.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.148-155
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• 2014

Most truck fires breaking out on the expressway are directly damaged by fire destruction of truck and freight and many of them cause indirect damage such as serious traffic holdups. This study analyzed the fire causes and their liability of the 25-ton truck fire breaking out during expressway driving. This truck fire was caused by manufacturing defect of return spring of a braking system. The fire liability rested with a maker(manufacturer) rather than a truck owner or a driver and the maker also bore fire liability based on the Product Liability Law.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.125-130
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• 2019

A gas-spring has been used in many areas and its use is increasing because it can be designed for a range of purposes. In this study, the behavior of a piston with an orifice hole inside the gas-spring cylinder was predicted using computational fluid dynamics (CFD). The piston was designed to reduce the reaction force if the gas-spring is compressed and to move at a low speed when it is returned. The analysis showed that if the initial gas pressure in the gas-spring is increased to a certain level, the speed of the piston would not decrease with time but will remain constant. The effects of orifice hall size on the piston return speed were investigated. Reducing the size of the orifice hole will increase the pressure difference on both sides of the piston, reduce the piston speed, and make it more constant. On the assumption of a constant speed of the piston, a theoretical solution to the return speed of the piston was derived according to the initial gas pressure, and the results for several initial gas pressures were compared with those of CFD. Comparison studies showed similar results for both methods.

• Proceedings of the ESK Conference
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• 1997.04a
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• pp.145-149
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• 1997

General joystick using spring only has a vibration when operaor drops the joystick. If it is used as input of motorized wheelchair, its system have a serious problem which operator fall into dangerous situation. Therefore, In this paper proposed non-vibration joustick which control a motorized wheelchair. Non-vibration joystick was designed which return to origin point when operator drops joystick by mistake. Reflected force of non- vibration joystick is defined as addition displacement and variation rate. And each parameter has elasticity of spring and viscosity of DC servo motor. Through simulation for virtual environment, we found two coefficient to return origin point smoothly when a disabled person drops the joystick. In case of larger elastic coefficient of spring than viscous coefficient, we confirmed the result has the equal vibration of general joystick (under-damping). In opposite case, joystick returned to origin point with excessive force. As a application of non-vibration joystick, we experimented wall-following controlling. In this trial, we corroborated that joystick follows smoothly around the corridors.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.799-800
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• 2007

• Journal of the Daesoon Academy of Sciences
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• v.48
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• pp.199-237
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• 2024

Donghak-gyo, the Teaching of Eastern Learning, is a new religious order founded by Kim Ju-hee, centered around the Donghak (Eastern Learning) lineage. The core thought conveyed in the lyrics of Donghak-gyo songs (gasa) can be identified as the concept of 'Return to the Former World (先天),' considering the frequency of the term and the content of the recited verses. The view of time and destiny (時運觀) held by Eastern Learning emphasizes the concept of 'Another Great Opening.' Donghak-gyo's perspective on time and destiny is further rooted in the concept of 'Return to the Former World.' Donghak-gyo particularly emphasizes the term 'Former World,' and incorporates the Study of Changes (易學) into their songs. They recite verses that depict the situation of the Great Opening as an interaction between yin and yang. In Donghak-gyo, it is emphatically asserted that the completion of the Later World's destiny leads to the achievement of the 'Return to the Former World.' It is sung that with the restoration of destiny associated with the 'Return to the Former World,' the symbolic 'Spring (春)' represented by the virtue of Wood (木德) will return. Donghak-gyo describes the unfolding of a new cycle of destiny (運數) as the 'restoration of Changes (易).' When this occurs, they refer to the emerging new world, characterized by a new order and norms, as the 'Return to the Former World,' asserting that a 'moral world' will be established, leading to the development of a moral civilization. It is also sung that the restoration of the destiny associated with the Return to the Former World is akin to the restoration of the Heavenly Dao (天道). The characteristics of the concept of the Return to the Former World are threefold: firstly, it advocates a nostalgic system; secondly, it is a backward-looking thought; and thirdly, the idea of 'cyclical repetition' encourages tangible actions such as 'returning to the origin' or 'restoring fundamentals.' The concept of Return to the Former World in Donghak-gyo, unlike many new religions of those days, provided a unique conceptualization and understanding of the Former World and presented a new framework for interpretation. It moved away from the notion of discarding the Former World as a relic of an outdated era, and instead interpreted it as a new era to be embraced. Therefore, the concept of 'Return to the Former World' in Donghak-gyo should be re-assessed as one of the ideologies that inherits the pursuit of returning to and restoring the past in Eastern traditions. However, it can be criticized for lacking a concrete methodology with regards to the 'Return to the Former World.' Additionally, it is noted for deficiencies in ethical consciousness and moral virtues. Furthermore, its explanation about the Former World come across as insufficient. Thus, the concept of the 'Return to the Former World' in Donghak-gyo seems to be characterized more by declarative slogans than substantive content.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.2
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• pp.6-11
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• 2010

For the purpose of reducing the energy consumption in the house heating, the various devices have been developed. One of these is to control the flow in the heat pipe and the flow control valve using shape memory alloy(SMA) spring is proposed in our study. The proposed house heating system is to save the gas consumption and the remote control system is designed for the convenience of using the proposed valve. The developed valve consists of SMA spring, disk, return spring, and regulation handle. The regulation handle is for supplying the additional hot water and is controlled by remote-control-motor. In order to design the remote control system, the Zigbee wireless communication protocol is used. The performance of the proposed valve structure is shown through the experimental result.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.3
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• pp.63-72
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• 2010

This study was conducted to investigate the current status and the improvement plans of the ecosystem conservation fund return projects. In 2007, there was a reformation of the ecosystem conservation fund system but the fund return projects were not vitalized up until now. In this study, 35 of ongoing and finished fund return projects were investigated on their types, sites, costs, local governments, and time required to return the fund. Through the on-site survey of 9 finished projects (4 biotope, 2 corridor and 3 natural conservation facility projects), construction and management conditions were investigated. The main findings are as follows: Among the five fund return types, 17 cases were biotope restoration projects, 4 cases were ecological corridor projects, and 1 case was a nature replacement project. In the case of project sites, there were 14 cases near schools and public facilities, 8 cases near rivers or streams, and 2 cases near ponds or wetlands. For the construction costs, there were 19 cases (65% of all the projects) that cost less than 300 million won. In terms of the involvement of the local government, most of the fund return projects were concentrated in Gyeonggi province and Ulsan city, and there were some local governments outside of these regions that did not carry out any return projects at all. Lastly, in the case of fund return time required, 35% of the fund returns were completed within 5 months, but the overall average fund return time was 9.8 months. In respond to the above study results, the improvement plans to encourage fund return projects are as follows: To diversify return types and sites, piloting and modeling projects for the representative types and sites should be preceded. To emerge from customary small-scaled projects, incentives to encourage large-scale and ecological networking projects should be considered. In addition, in order to write up business plans for the fund return projects, long-term investigations of at least 2 seasons from spring to fall are necessary. Finally, for the continuous management and maintenance of the ecological fund return sites, easier way for the citizens to actively participate in the projects should be incorporated.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.3
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• pp.324-333
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• 2012

The conventional medium and large caliber gun, in general, utilize the hydro-pneumatic recoil mechanism to control the firing impulse and to return to the battery position. However, this kind of mechanism may cause the problems like the leakages and the property changes in oil and gas due to the temperature variations between low and high temperatures. Accordingly, the friction spring mechanism has recently been researched as an alternative system. The friction spring mechanism consists of a set of closed inner and outer rings with the concentric tapered contact surfaces assembled in the columnar form, and can only be used under the compression load. When the spring column is axially loaded, the tapered surfaces become overlapped, causing the outer rings to expand while the inner rings are being contracted in diameter allowing an axial displacement. Because of friction between tapered contact surfaces, much higher spring stiffness is obtained on the stroke at the increase in load than the stroke at the decrease. In this paper, the dynamic equations regarding the friction spring system and the design approach have been investigated. It is also tried for a dynamic model representing the recoil motion and the friction spring forces. And the model has been proved from firing test using a gun system with friction springs. All the results show that the recoil mechanism using friction springs can substitute for the classic hydro-pneumatic recoil system.