• Journal of Welding and Joining
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• 제22권4호
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• pp.43-49
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• 2004

Conventional method for electrode force application in resistance spot welding(RSW) processes is to use pneumatic cylinder. However, due to its inherent problems in pneumatic power system such as compressibility of air and poor transient response characteristics, new electrode force system with servo control are recently introduced in RSW machine. This machine is called “servogun”. The purpose of this study is to evaluate performance of servogun in case of spot welding of aluminum alloy. Aluminum alloy(A5052) sheets are spot welded using pneumatic gun and servogun. Both results are compared by means of macro cross-section etching test and tensile shear strength test. Numerous previous research have reported nugget with many voids and cracks are not uncommon defects in spot welds with aluminum alloy. The experimental results show similar defects in case of pneumatic gun. In contrast, use of servogun considerably reduced generation of voids and cracks. In case of step-wise increased forging force at the end of welding cycle with servogun, crack-free and void-free nuggets have been observed. The performance of servogun has been also verified by series of tensile shear test. Higher strength values have been achieved with servogun in comparison to that of pneumatic gun.

• 전력전자학회논문지
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• 제8권5호
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• pp.397-406
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• 2003

저항 스폿 용접은 자동 용접라인 등에서 널리 사용된다. 최근에는, 대량으로 생산하는 산업현장에서 좀 더 정교한 품질 제어가 필요하게 되었고 마이크로프로세서를 채용한 제어의 다양한 적용으로 높은 생산성과 더 나은 용접품질을 얻을 수 있게 되었다. 본 연구에서는 인버터 타입 파우어 소스와 용접 서보건을 개발하였다. 그 결과, 기존의 공압건에 비해 몇 가지 장점을 갖게 되었는데 그 중의 하나는 용접공정 중에 정밀한 가압력 제어가 가능하게 되었다. 또한, 작업시간도 줄고 경비도 절감되는 부가 효과를 얻을 수 있다고 판단된다.

• 한국공작기계학회논문집
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• 제17권2호
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• pp.90-96
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• 2008

A pneumatic system was proposed to evaluate displacement accuracy of the pneumatic actuator without external load and to analyze capability of integration of the proposed valve system. The proposed pneumatic system consisted of a combination of pneumatic valves, two proximity sensors, and a programmable logic controller(PLC). The position controller is based on the PLC controller connected with the proximity sensors. Displacement accuracy of the pneumatic cylinder stroke was tested by varying air pressures of the supply and discharge-side and strokes of the pneumatic cylinder. The displacement accuracy of the pneumatic cylinder stroke increased as the supply and discharge side of air pressure increased at the stroke length of 133mm. Also the displacement accuracy increased as the stroke length increased with a fixed supply and discharge side of air pressure of the pneumatic cylinder as 3.5 and $4.5kg/cm^2$, respectively. The most accurate displacement of the pneumatic cylinder(i.e., standard deviation of 0.01 mm) was obtained at the supply and discharge side of air pressure of 4.0 and $5.0kg/cm^2$, respectively, and strokes of 170 and 190 mm among arbitrarily selected supply and discharge side air pressures and strokes.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.599-602
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• 1999

In this paper, we attempt to control the pressure between two specimens using a servo gun in the resistance spot welding process. Servo guns have some advantages over pneumatic guns in that the fast response, the precise position control, and the accurate torque control are assured by virtue of the servo motor control. To demonstrate the practical significance of our results, we present some experimental results..

• 한국산학기술학회논문지
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• 제15권8호
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• pp.4742-4748
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• 2014

전북 익산시 R회사에서 기 개발된 세미오토 클러치는 수동클러치 차량의 기어 변속시 클러치 페달을 밟아야하는 불편함을 해소하고자 만들어진 장치로써 클러치 페달을 밟지 않고, 운전자가 기어봉에 위치한 스위치 조작만으로도 클러치 동작을 제어할 수 있다. 차량의 변속과정에서 클러치 동작을 제어하기 위해 센서를 설치하여 차량정보를 수집하여 제어하였다. 그러나, 센서 기반의 제어기는 열악한 운전조건에서 고장 원인이 되고 있으며, 차량에 설치하고 보수하는 과정에서 시간소요가 과다하여 많은 불편을 가지고 있었다. 이를 위해 본 연구에서는 차량의 ECU와 CAN통신을 통해 차량의 주행정보를 수집하여 제어하고, 공압 액추에이터로 클러치를 동작시키는 세미오토 클러치를 개발하였다. 개발된 공압 액추에이터의 정상적인 동작을 위해서는 최소 3bar이상이 요구되었다.

• 한국산학기술학회논문지
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• 제13권3호
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• pp.1325-1329
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• 2012

본 논문은 실내 사격 전용 총기의 개발, 고속의 레이저 인식 알고리즘 개발을 통하여 다양한 그래픽 컨텐츠와 연동할 수 있는 실내용 스크린 사격 시스템을 제안한다. 내구성이 강하며 공압 솔래노이드 밸브 제어와 비가시 레이저를 전용 총기에 적용하였으며, 비가시 레이저를 고속으로 인식하여 그래픽 엔진와 상호작용하는 방법을 개발하여 실내용 스크린 사격 시스템을 상용화 하고자 한다.

• 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.

• Journal of Trauma and Injury
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• 제26권1호
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• pp.26-29
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• 2013

We describe the case of a 56-year-old man who had been shot by a pneumatic nail gun in the chest during work. He had removed the nail by himself immediately at the accident field. He visited to the emergency department of a local hospital and, after a simple dressing and simple history had been taken, he was referred to our emergency department for penetrating thoracic injury. Immediately, Transthoracic echocardiography were done and showed moderate hemopericardium. Patient had been hydrated and transported to the operating room. After cardiac wound repaired by midsternotomy, the patient was discharged on the 13th postoperative day without complications except mild mitral valve regurgitation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.473-478
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• 2005

Active suspension system improves ride quality with optimized suspension force, generated by electric, hydrolic or pneumatic power and controlled by micro-processor under various operation condition of train, while Semi-Active susepsion system provides optimized and controlled characteristics of suspensions such as damping coefficient without external energy. The benefits fo Semi-Active suspension are no required power source and to be made compact with lower cost. Train with narrow gauge could be more unstable than one for normal or wide gauge, and it could be more vibrated than others one by external force such as aerodynamic force and track irregularity. So, the reduced ride quality could be improved with appling with Semi-active suspension system. In this report, the Semi-Active suspension system for narrow gauge train shall be proposed and to prepare the Roller Rig test of this train, integration of system, development of control algorithm and confirmation of its performance with simulation tool would be taken.

• Structural Engineering and Mechanics
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• 제60권5호
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• pp.829-849
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• 2016

In this paper, experimental as well as numerical analysis of Glass Fiber Reinforced Polymer (GFRP) laminated composite has been presented under ballistic impact with varying projectile nose shapes (conical, ogival and spherical) and incidence velocities. The experimental impact tests on GFRP composite plate reinforced with woven glass fiber ($0^{\circ}/90^{\circ}$)s are performed by using pneumatic gun. A three dimensional finite element model is developed in AUTODYN hydro code to validate the experimental results and to study the ballistic perforation characteristic of the target with different parametric variations. The influence of projectile nose shapes, plate thickness and incidence velocity on the variation of residual velocity, ballistic limit, contact force-time histories, energy absorption, damage pattern and damage area in the composite target have been studied. The material characterization of GFRP composite is carried out as required for the progressive damage analysis of composite. The numerical results from the present FE model in terms of residual velocity, absorbed energy, damage pattern and damage area are having close agreement with the results from the experimental impact tests.