• 드라이브 ㆍ 컨트롤
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• 제9권2호
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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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• 제20권3호
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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.

• 한국자동차공학회논문집
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• 제22권2호
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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.

• 한국산학기술학회논문지
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• 제20권12호
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• pp.125-130
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• 2019

가스스프링은 그 사용 목적에 따라 다양한 설계가 가능하여 많은 분야에서 사용되고 있고 그 사용량도 계속하여 증가하고 있다. 본 연구에서는 가스스프링을 압축할 경우 반발력을 감소시키고 피스톤이 복귀할 때 저속으로 복귀할 수 있도록 설계된, 오리피스 홀을 갖는 피스톤의 가스스프링 실린더 내부에서의 거동을 전산유체해석을 이용하여 예측해 보았다. 해석결과 가스스프링 내의 초기 가스압을 일정 수준 이상으로 증가시키면 피스톤의 복귀속도가 시간에 따라 감소하지 않고 일정하게 유지됨을 알 수 있었다. 오리피스 홀 사이즈가 피스톤 복귀속도에 미치는 영향을 해석을 통해 알아보았다. 오리피스 홀 사이즈를 줄이게 되면 피스톤 양단의 압력 차가 증가하여 피스톤 전진속도가 감소하게 되고 보다 등속으로 운동하게 됨을 알 수 있었다. 마지막으로 피스톤의 속도가 일정하다는 가정에서 초기 가스압에 따른 피스톤의 복귀속도를 이론적인 방법으로 도출하였고, 여러 초기 가스압에 대한 해석 결과와 비교하였다. 비교결과 이론적으로 도출한 해와 해석결과로부터 얻어진 결과 값이 거의 일치함을 알 수 있었다.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1997년도 춘계학술대회논문집
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.799-800
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• 2007

• 대순사상논총
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• 제48집
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• pp.199-237
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• 2024

동학교는 김주희가 세운 동학계 신종교단이다. 동학교가사에 나타난 사상의 요체는 용어의 빈도수와 읊어진 구절의 내용을 고려하여 '도로 선천(先天)'사상이라고 볼 수 있다. 동학의 시운관(時運觀)이 '다시 개벽(開闢)'사상이라면, 동학교의 시운관은 '도로 선천(先天)'사상이다. 동학교에서는 선천이라는 용어를 특히 강조했고, 역학(易學)을 활용하여 노래했으며, '음양의 마주 봄'으로 개벽의 상황을 읊었다. 동학교에서는 후천의 운수마저 다한 다음에야 비로소 '도로 선천'이 이루어지리라고 강조한다. 이 '도로 선천'의 운수가 회복되면 목덕(木德)으로 상징되는 '봄<춘(春)>'이 다시 돌아올 것이라고 노래한다. 동학교에서는 새로운 운수(運數)의 전개를 '역(易)의 회복'으로 설명한다. 새로운 질서와 규범이 전개될 새 세상을 '도로 선천'으로 부르는데, 이때가 되면 '도덕세계'가 이루어져 도덕 문명이 전개될 것이라고 주장한다. '도로 선천'을 회복하는 운수가 바로 천도(天道)가 회복되는 일과 같다고도 노래한다. '도로 선천'사상의 특성은 첫째, 복고적 체계를 지향한다. 둘째, 과거지향적 사상이다. 셋째, '도로'는 '근원으로 돌아가자.', '근본을 회복하자.'라는 실제의 행동을 유발하고 권유하는 생각이다. 동학교의 '도로 선천'사상은 당대의 여러 신종교와는 다르게 선천(先天)에 대해 독창적인 관념과 인식을 부여했으며, 새로운 해석의 틀을 제시했다. 선천을 폐기해야만 할 낡은 시대로 규정했던 일에서 벗어나 지향해야 할 새 시대로 이해했다. 따라서 동학교의 '도로 선천'사상은 동양 전통의 과거로의 회귀와 복귀를 추구하던 일을 계승한 사상의 하나로 재평가되어야 하겠다. 하지만 '도로 선천'사상에 구체적 방법론이 매우 부족하다는 점은 단점으로 지적될 수 있다. 그리고 동학교의 '도로 선천'사상에는 윤리의식이나 도덕적 덕목이 부족하며, 정작 선천(先天)에 대한 설명이 부족하다. 따라서 동학교의 '도로 선천'사상은 선언적 구호에 그친 감이 있다.

• 한국기계가공학회지
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• 제9권2호
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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.

• 한국환경복원기술학회지
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• 제13권3호
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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.

• 한국정밀공학회지
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• 제29권3호
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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.