• Tribology and Lubricants
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• 제15권1호
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• pp.24-28
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• 1999

This paper describes a new pivoting technique to improve bearing performance in pivoted pad thrust bearings. This new technique adjusts the pivot line in a line pivoted pad thrust bearing to be parallel to the trailing edge of a sector shaped pad. Bearing performance factors such as load carrying capacity, frictional torque and flow rate are numerically investigated for conventional point-pivoted and line-pivoted pads and for the new parallel-line pivoting technique. It is shown that the load carving capacity can be maximized with the new technique.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.95-96
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• 2011

• 한국군사과학기술학회지
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• 제14권1호
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• pp.39-48
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• 2011

This study describes a range sensitivity of a canard controlled missile. An investigation was conducted into the relative importance of aerodynamic parameters on a guided missile. Also this study was analyzed by quantifying their effects on the missile range. To analyze the range sensitivity of a guided missile, a trajectory analysis program of a guided missile was developed. The range sensitivity analysis was conducted on a thrust, weight, drag and lift. The result of the range sensitivity analysis shows that the design parameters with the greatest effect on the missile range are thrust, drag, weight, and lift, in descending order of importance. The thrust on range extension is quite obvious to extend a range of a guided missile. In particular, the drag exhibited greater range sensitivity than lift at a guided flight. The result also shows that missile range could be maximized by applying the appropriate launch angle and canard pitch-up control.

• 한국추진공학회지
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• 제25권5호
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• pp.65-72
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• 2021

소형위성의 궤도조정 및 궤도유지에 활용될 수 있는 700 W급 홀추력기 랩모델을 개발하였다. 스케일링 방정식을 사용하여 방전채널의 크기를 선정하였으며, 자기장이 방전채널 중심선을 기준으로 대칭성을 가지면서 방전채널 바깥에서 최대가 되도록 설계하였다. 개발된 홀추력기의 방전시험은 2.0×10^-5 Torr 이하의 배경압력을 갖는 진공 환경에서 수행되었으며 추력 스탠드를 이용하여 추력을 측정하였다. 양극전압을 300 V로 고정하고 양극유량과 코일전류를 변수로 하여 추력을 측정하였으며, 양극유량 2.36 mg/s, 코일전류 2.4 A 조건에서 양극전력 620 W에서 추력 38 mN, 통합비추력 1,540 s, 양극효율 50 %로 가장 높은 성능을 보였다.

• Tribology and Lubricants
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• 제31권1호
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• pp.13-20
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• 2015

The impact beam, a beam-shaped reinforcement installed horizontally between the inside and outside panels of car doors, is gaining importance as a solution to meet the regulations on side collision of vehicles. In order to minimize pelvis injury which is the biggest injury happening to the driver and passengers when a vehicle is subject to side collision, energy absorption at the door impact beam should be maximized. For the inner panel, the thrust into the inside of the vehicle must be minimized. The impact beam should be as light as possible so that the extent of pelvis injury to the driver and passenger during side collision of the vehicle is minimal. To achieve this, the weight of the impact beam, has to be optimized. In this study, we perform a design analysis with a goal to reduce the weight of the current impact design by 30% while ensuring stability, reliability, and comparison data of the impact beam for mass production. We conduct three-point bending stress experiments on conventional impact beams and analyze the results. In addition, we use a side-door collision test apparatus to test the performance of beams made of three (different materials: steel, aluminum, and composite beams).