• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3C
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• pp.103-108
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• 2011

In this study, the limitations of large strain resonant column and torsional shear tests apparatus are described and solutions to the limitations are also described. The limitations are rotational distance, limited torque, and measurable deformation system, respectively. To resolve the rotational distance, the bottom platen was modified. And the four-armed drive plate was modified into eight-armed drive plate and the drive coil connection was changed to obtain powerful torque.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.885-890
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• 1998

SMART 냉각재순환펌프는 수직형 축류펌프로 분류되며 작동되는 환경의 특성상 캔드모터 펌프로 설계하였다. 냉각재순환점프의 전체 구조에 대한 개념설계를 수행하였으며 펌프의 주요부품인 회전측 집합체, 베어링 집합체, 전동기를 설계하였다. 베어링의 구조와 형상설계를 수행하였고 전동기는 농형유도 전동기로 설계하였으며 회전자의 슬롯에 대한 상세설계와 고정자의 슬롯에 대한 상세설계를 수행하였다. 앞으로 회전축의 동특성 해석, 임펠러의 캐비테이션 시험, 베어링의 내구성 시험, 펌프몸체의 응력해석을 수행할 예정이다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• v.10 no.1
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• pp.72-75
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• 2005

사보니스 4익 풍차의 크기에 따른 토크, 회전수, 동력을 각기 다른 풍속에서 측정하였으며 열변환조의 회전수를 증가시키기 위하여 중속기어를 부착하여 풍력의 열변환시험을 하였다. 기어비 1:18 까지 증가시켜 로타의 회전수를 최고 180rpm으로 증가시켰지만 열변환능력은 크게 개선되지 않았다. 풍차의 크기와 동력의 관계에 관한 심층적 이론분석이 필요할 것으로 판단된다.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.230.1-230.1
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• 2012

본 논문에서는 대구경 광학탑재체의 조립, 정렬 및 시험에 사용되는 고정밀, 고안정 짐발장치의 개발에 대해서 소개하고자 한다. 광학탑재체의 광학시험을 위해 사용되는 짐발장치는 광축높이를 유지하기 위해서 높이조절이 가능해야하고, 조립과정과 광학시험과정 그리고 시험 후 광학탑재체를 짐발 장치로부터 분리하기 위해 수평상태와 수직상태로의 회전이 가능해야 한다. 광학측정 시험과정 중에 결상위치의 미세한 조절을 위해 광학탑재체를 수평상태에서 상하좌우 정밀한 회전이 가능해야한다. 우주궤도환경 하에서 성능측정을 위해 열진공체임버 안에서의 광학시험이 필요하므로 짐발장치를 구성하는 재질은 모두 진공사용이 적합한 것이어야 한다. 광학측정 중에 측정설비주변에서부터 인가된 외란은 광학시험과 같은 민감한 시험에서는 철저하게 제거되어야 하는데, 이와 관련하여 짐발장치의 광학측정시험형상에서의 고유진동수와 같은 동적 특성도 설계과정에 반영하여 안정적인 측정 장치가 되도록 고려되어야 한다.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.50-59
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• 2005

This paper described performance test of 1st prototype "Tail-Fan" system. KARI(Korea Aerospace Research Institute) developed "Tail-Fan" system as a kind of helicopter anti-torque system(ATS) and designed ATS performance test-rig for Tail-Fan system performance test. For Tail-Fan system performance tests, firstly, test-rig operation tests were carried out for verification of design specifications. And natural frequencies of fan blade and test-rig were measured respectively. To find the operation rotating speed for performance tests, vibration tests using accelerometers on tail gear box(TGB) were carried out. Through the fanplot and vibration test results, rotational speed for Tail-Fan performance test to avoid a resonance were found and performance tests were carried out in flight conditions. We analyzed test data by non-dimensionalization. Through this results, 1st prototype "Tail-Fan" system was satisfied with design requirements.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.10
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• pp.60-65
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• 2003

An experimental study was performed to understand ignition characteristics of gas turbine combustor with rotating fuel injection system. Liquid fuel applied to the inner surface of rotating fuel nozzle which was driven by high speed electrical motor is flung away by centrifugal forces. The real scale combustor and test rig was manufactured and tested under atmospheric condition in KARl combustion test facility. From the test results, this combustor ignition characteristics are highly dependent upon fuel nozzle rotating speed. Futhermore, combustor exit gas temperature was rapidly changed by increasing or decreasing the fuel nozzle rotating speed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.11
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• pp.1092-1100
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• 2011

A C-band ground-based rotational SAR system is presented in this paper. The rotaional SAR system is a test-bed for future rotational SAR systems which can be deployed in space and on a tower. The test-bed system is designed for imaging the electromagnetic scattering from earth surfaces and buried targets. This paper also presents the examination results of the generated SAR images. This rotational SAR system is basically consisted of the network-analyzer based HPS(Hongik Polarimetric Scatterometer) and a horizontally rotating arm. Several SAR images were obtained using the rotational SAR system for various target areas. To verify this system, we simulated the SAR images for the rotational SAR using the FDTD algorithm and compared between the measured and simulated SAR images. The rotational SAR system is operated at the center frequency of 5 GHz and various frequency bandwidth within 0.5~2 GHz to change the resolution of SAR images.

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.196-202
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• 2017

A very long test track is required for high-speed operation test of the real-scale Linear Synchronous Motor (LSM) for ultra-high-speed trains. The required length results in huge construction cost and economic loss if any error occurs during development. Therefore, validation study of the LSM design technology using a low-cost small-scale model must be carried out in the early research stages. It is possible to deduce an optimal winding method for the armature and determine the mechanical properties of the LSM through a performance tester that applies a rotary-type small-scale LSM model. In addition, it is possible to utilize previous research on LSM control systems. Therefore, a basic design model, comprising a rotary-type LSM tester that meets the requirements for the propulsion of 600km/h-class ultra-high-speed trains, is derived in this study. Finally, an optimal model, which has a stable structure under the condition of 1500rpm or more high-speed rotation, is derived by electromagnetic and mechanical stiffness analysis.

• Journal of KSNVE
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• v.8 no.2
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• pp.331-335
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• 1998

A design modification was made on the 9-th stage wheel dovetail of a high-intermediate pressure (HIP) turbine rotor for a fossil power plant that necessitates the use of new long-shank buckets for the row. A bucket vibration test is necessary to verify that the new 9-th stage buckets have adequate frequency margin from a nozzle passing frequency when running at speed. A finite element analysis (FEA) has been performed using a commercial S/W to approximately estimate bucket natural frequencies, and thus to help the vibration test. A row of the new buckets has assembled on the HIP rotor for the vibration tests using dynamic balancing facilities. The tests have been done during deceleration run with air excitation. The test results are compared with the calculation using our empirical formula, and show that the modified design meets the frequency-margin requirements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.614-618
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• 2018

The changes in the mechanical properties according to the width of the tool shoulder, rotation speed and moving speed in friction stir welding (FSW) are evaluated using Al 6061-T6. The results indicated that the tensile strength value increases with increasing rotation speed. The higher the moving speed of the tool shoulder, the lower the tensile strength, regardless of the tool type. A higher tensile strength value was generally obtained with a tool shoulder diameter of 12mm (TSD12) than with 8mm. When the moving and rotation speeds exceed a limiting value, a stabilization stage is reached, in which (the tool shoulder diameter?) no longer affects the material properties. At a tool shoulder diameter of 8mm (TSD8), the material properties are decreased and the mixture of material in the welding area is incomplete in comparison with the tool type of TSD12. The tensile strength value is decreased at a rotation speed of 1500 rpm. As a result, a rotation speed higher than the threshold value is needed in order for and the transition temperature to be reached, which allows the complete mixing of the material in the welding area.