• Aerospace Engineering and Technology
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• v.8 no.1
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• pp.1-9
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• 2009

The ground integration test of Smart UAV has been performed according to the flight test plan. The flight test of full scaled model will be performed followed by 4 DOF ground rig test and a tethered hover test. Smart UAV is the first indigenous tiltrotor aircraft which can fly with fast cruise speed and take off or land vertically. In order to prove the flight control law of Smart UAV, the 40% scaled airplane was developed and have been tested. During flight test of small scaled model, many unique and unexpected problems occurred. After clearing these problems, fully automatic flight test was performed successfully. The experiences about many trouble shooting and resolving the problems would be basic material to avoid the unexpected but similar flight test problems hidden behind of the full scaled Smart UAV. This paper presents the detailed procedures of trouble shootings to solve the unique problems which occurred during the flight test of small scaled tiltrotor UAV.

• Elastomers and Composites
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• v.49 no.1
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• pp.73-81
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• 2014

Friction and wear behaviors of natural rubber(NR) compounds were investigated using a blade-type abrader. The effects of temperature, normal load, and rotation speed on wear rate were studied, and wear behaviors of deteriorated compounds were also evaluated. As the rotation speed of specimen and the normal load to specimen increased, the wear rate increased. However, as the experimental temperature increased, the frictional coefficient decreased and the wear rate decreased accordingly. It was found from the wear studies that a power-law relation works between the frictional work input and the wear rate. It was observed that the wear rate dramatically increased by the degradation of the rubber specimen. The wear pattern was developed and the bigger ridge space of the pattern was observed usually in the higher normal load applied. In determining the wear rate of rubber compound, the continuous measurements of wear distance using the blade-type abrader could be successfully used instead of intermittent measurements of wear-loss weight.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.119-131
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• 2014

For quick and accurate ground investigation in wide construction site being not easy to access, advanced dynamic cone penetration test equipment was developed based on widely used equipment abroad. Advantages of existing equipment of portability and simple testing method were reflected in the new developed equipment. Meanwhile, by extending connection of lower rod, penetration depth is raised to 6m from 1 m of the existing equipment. Moreover, by assembly of hammer (2+3+3kg) and cone (3 types) etc., it is possible to perform test under the same conditions with those by German and Japan dynamic cone penetration test equipment (Tsukuba, PWRI and SH types). Auxiliary equipment was applied to make sure of perpendicularity as penetration depth increases. Applicability of the new developed equipment was evaluated through tests on various fields and its reliability was verified.

• Tunnel and Underground Space
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• v.32 no.4
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• pp.243-253
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• 2022

In this study, the cutting efficiency of TBE (Tunnel Boring Extender) was evaluated by using rotary cutting tester. In the rotary cutting test, a specimen which has a drilled hollow hole at the center was made of rock-like material. The specimen was cut by UDC (undercutting disc cutter) with spiral cutting path to simulate the cutting process of TBE. The cutting forces and specific energy were evaluated under different cutting conditions. The results indicated that the cutter forces of UDC linearly increased with the vertical and radial penetration depths. Among the three directional cutter forces, the normal force is larger than other force components. While the specific energy decreased with the two penetration depths, in particular, it was presumed that the specific energy was minimized at a certain value of the ratio of radial to vertical penetration depth.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.455-462
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• 2017

In recent decades, many researchers have been struggling to developing the compound aircraft that is capable high speed and VTOL flight. And in recent years, multi-copters are very popular because of having advantages of VTOL and easy handling, but they are lack of doing long-range mission. Therefore, we presents simple aircraft architecture which is equipped fixed wing, multi propellers and no control surfaces. In this paper, we designed the attitude control for the compound aircraft prototype and measured the attitude control performance with flight test for validating prototype's performance. We analysed the attitude control test result comparing with similar size of a fixed wing aircraft. The performance was almost same as fixed wing aircraft.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.240-244
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• 2005

현재 강변여과수 개발은 수직정 위주로 개발되어졌으나, 수직정을 이용한 취수 방식은 산출량에 대한 한계를 가지고 있어 대용량 취수를 위해서 많은 취수정 착정이 불가피하다. 취수정 증가와 더불어 유지관리상의 문제점을 가지고 있으며 실제 운영에서 문제점이 나타나고 있는 실정이다. 이러한 수직정 취수정의 문제점을 해결하기 위해 방사형 집수정을 이용한 강변여과수 개발이 시도 되고 있다. 현재 창원시 대산면 일대에서 국내최초로 방사형집수정을 이용한 강변여과수 개발이 진행되고 있으며, 현재 방사형 취수정 1기가 시공 완료되어 시험 가동 중에 있다. 방사형 집수정에 의한 강변여과수 개발은 대용량 취수를 목적으로 설치되기 때문에 산출량뿐만 아니라 집수정 인근의 수위하강에 특성이 중요한 요소 중에 하나이다. 본 연구에서는 창원시 대산면 일대에서 진행되고 있는 방사형 집수정 설치에 따른 강변여과수 산출시 집수정 인근 수위하강 특성 파악을 위한 모니터링을 목적으로 실시하였다. 수위하강 특성 관측을 위해 양수실험을 위해 대용량 양수펌프 설치, 유량검증을 위한 대형 웨어 설치, 수위변화 측정을 위해 집수정 30m 반경에 8개의 관측정을 착정하여. 디지털 수위측정기를 설치하여 수위하강 특성을 모니터링 하였다. 수위 모니터링 결과 취수정의 수위하강 특성과 유사하게 수평정의 수위하강 경향 나타났으며, 강변에 가까운 수평정의 수위하강은 약 $30\% 감소하였으며, 집수정 양수량에 변화에 따라 민감하게 반응하지 않는 특성을 나타냈다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.573-578
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• 2002

양파박피기 개발을 목적으로 수행된 본 연구에서는 공정상 필요한 뿌리절단장치에 관하여 시험 분석하였다. 뿌리를 절단, 제거하는 데 적합한 칼날의 종류, 회전속도와 이송속도, 및 소요동력 등 제 특성을 구명하여 적절한 회전칼날을 제작 사용함으로써 능률 높은 양파박피기를 개발하고자 수행한 결과를 요약하면 다음과 같다. 1. 양날형, 축날형, 원추형, 및 원통형 등 직경 30 mm의 칼날을 제작하여 실험하였던 바, 양파의 뿌리절단에는 구부린 칼날로 파내기를 하고 수직칼날로 금긋기를 동시에 할 수 있는 양날형이 가장 좋은 것으로 나타났다. 2. 양파의 뿌리부가 100% 절단이 되고 소요동력이 낮으면서 절단시간을 단축할 수 있는 최적의 작동조건은 칼날의 무부하 회전수 630 rpm, 이송속도 0.08 m/s인 것으로 나타났고, 그때의 최대토크는 5.25 kg·cm이었으며 최대소요동력은 33W로 나타났다.

• 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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1188-1191
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• 2017

Thrust is one of the crucial performance parameter of a combustion chamber in the combustion chamber development test. So it is very important to measure an accurate thrust. Thrust calibration test was performed to identify the system characteristics, resistance and linearity of a vertical thrust measurement system(TMS) for accurate thrust measurement. It has been found 6.9% ~ 8.6% errors between the measured thrust by TMS calibration equations and theoretical thrust. It has been confirmed that the TMS calibration is necessary to be performed with the propellant lines connected to the combustion chamber for accurate thrust measurement.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• v.10 no.2
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• pp.32-35
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• 2005

밭고랑 옆의 해가림시설 지주목에 파이프라인을 설치하고 방제장치를 탑재한 주행장치가 자동으로 파이프를 추적하면서 농약을 살포 할 수 있는 방제기를 개발하여 인삼재배포장에서 성능시험을 실시하였다. 그 결과를 요약하면다음과 같다. 가. 인삼재배용 방제기의 주행장치는 동력원으로 축전지를 사용하는 DC모터에 의한 4륜 구동형으로 제작하였고, 방제장치는 수직 붐노즐 방식으로 쌍선형 노즐을 좌우에 3개씩 부착하고 살포각도를 조절할 수 있도록 제작하였으며, 인력으로 골간 이동시키는 방식이다 나. 성능시험결과 주행속도는 0.3m/s이고, 장애물이나 요철부의 통과 가능높이는 4cm였고, 작업성능은 38분/10a로 나타났다. 다. 방제성능은 피복면적비를 측정한 결과 인삼 잎 앞면은 100%, 뒷면은 40%이상으로 분무입자의 부착률이 양호한 것으로 나타났다.