• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.5
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• pp.523-531
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• 2012

The performance simulation of a desiccant rotor, which is a core component of a desiccant cooling system, was conducted on the basis of a theoretical solution of the heat and mass transfer process in the rotor. The simulation model was validated by comparing simulation results with experimental data; reasonable agreement was observed. The effect of the rotation speed on the performance of the desiccant rotor was investigated for various operation conditions: temperature (50 to $70^{\circ}C$), humidity ratio (0.01 to 0.02 kg/kg DA), and flow rate of regeneration air. The optimum rotation speed was determined from the maximum moisture removal capacity (MRC) of the desiccant rotor, and it was found to vary with the operation conditions. Further, the correlation for the optimum rotation speed was determined by regression analysis.

• Air Cleaning Technology
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• v.31 no.4
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• pp.23-33
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• 2018

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.7
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• pp.561-568
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• 2013

After we designed Bearingless rotor hub system for 7,000lb class helicopter, flexbeam fatigue analysis was conducted for validation of requirement life time 8,000 hours. sectional structural analysis method applying elastic beam model was used. Fatigue analysis for two sections of flexbeam which were expected to weak to fatigue damage from result of static analysis was conducted. Extension, bending and torsion stiffness of flexbeam section shape was calculated using VABS for structure analysis. S-N curve of two composite material which composed flexbeam was generated using wohler equation. Load analysis of bearingless rotor system was conducted using CAMRAD II and load analysis result was applied HELIX/FELIX standard load spectrum to generate bearingless rotor system load spectrum which was used flexbeam fatigue safe life analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.5
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• pp.439-446
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• 2016

The characteristics of bearingless main rotor of helicopter are investigated through non-rotating tests and rotating tests. The stiffness and natural frequencies of rotor blades, flexbeam, and torque tube which are core components of baearingless rotor are measured to obtain input material properties for rotor analysis. The functional test on ground for assembly of one hub with damper, snubber, and no blade is carried out to check interfaces between components, kinematics of components, and pitch motion ranges under applied loads including centrifugal load. The 4-bladed bearingless rotor with 5.82m of rotor radius is tested on the whirl tower with rotation plane of 9.65m height. The thrust and power are measured to obtain hover performance and the frequencies and dampings of the rotor are obtained by excitation of cyclic pitch by hydraulic actuators.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.7
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• pp.539-547
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• 2021

Helicopter rotor blade is required to be designed by considering the interacting effects among aerodynamics, flexibility, and controllability. The reverse design allows the structural components to have common characteristics by using the configuration numerics and experimental results. This paper aims to design the composite rotor blade which will feature common characteristics with that of BO-105. The present engineering design procedure is done by dividing the rotor blade into a few sections and composite laminates across the cross section. For each section, variational asymptotic beam sectional analysis (VABS) program is used to evaluate its flapwise, lagwise, and torsion stiffnesses to have discrepancy smaller than certain tolerance. Finally, CAMRAD II is used to predict the stress acting on the rotor blade during the specific flight condition and to check whether the present deign is structurally valid.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.74-74
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• 2017

밀식파종 묘 이앙 시스템은 벼농사 생력화를 위한 재배법으로 비용 및 노동력을 획기적으로 줄일 수 있어 시간과 잉여 공간의 유효 활용을 통해 영농 규모의 확대로 인한 농업의 경쟁력을 높일 수 있다. 하지만 밀식 파종한 육묘를 관행과 동일한 1개 소당 3~4주 이앙 가능한 식부부 개발은 미흡한 실정이다. 밀식 파종한 육묘를 기존 이앙기로 이앙작업을 할 경우, 1개 소당 이앙되는 양이 많아져, 벼 생육을 저하 시키는 요인이 된다. 이러한 부분을 해결하기 위해서는 이앙 작업에 직접적으로 영향을 주는 이앙기식부부의 로터케이스, 이앙암을 분석하여 밀식파종 묘에 적용할 수 있는 기술이 필요한 실정이다. 본 연구에서는 식부부의 로터케이스, 이앙암을 3D 스캐너를 활용하여 스캐닝 작업을 한 뒤 역설계를 통하여 도면화 작업을 실시하여 식부부 궤적 분석을 실시하였다. 분석은 다물체 동역학 해석 프로그램인 Recurdyn(V8R4, Functionbay)을 활용하여 진행하였다. 분석결과, 식부부에 위치하는 이앙집게의 형상 및 로터케이스의 기어 배열에 따라 식부부가 형성하는 궤적의 형태가 달라지는 것을 확인 할 수 있었다. 이러한 부분은 밀식파종 묘에 적합한 궤적 분석 및 현장 필드 실험에 필요한 기초자료로 활용하고자 한다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.8
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• pp.784-790
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• 2012

This paper describes a stability and dynamic characteristics of bearingless helicopter main rotor in hover. Baseline rotor configuration is defined and modal analysis for the configuration is taken to verify the dynamic characteristics. The kinematic pitch-lag couplings through ways of pitch link installation are analyzed to know effects on loads, frequencies and stability. The effects of pitch link attachments in spanwise direction and chordwise direction as well as pitch link inclination on thrust, power, flpa-lag-pitch mode frequencies and inplane damping are examined. Pitch link at trailing edge location in chordwise direction has influence on aeroelastic stability of the rotor. Also, the pitch link with negative inclination angle makes inplane damping increase.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.382-386
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• 2006

Three dimensional numerical analysis of the supersonic turbines with different rotor tip clearances was conducted to analyze the effect of the tip gap clearance variations on the turbine performance. The result showed that the turbine performance deteriorates and the tip leakage increases by the effect of the rotor tip clearance and the tip leakage affects turbine performance degradation dominantly.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.394-399
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• 2012

This paper describes a stability and dynamic characteristics of bearingless helicopter main rotor in hover. Baseline rotor configuration is defined and modal analysis for the configuration is taken to verify the dynamic characteristics. The kinematic pitch-lag couplings through ways of pitch link installation are analyzed to know effects on loads, frequencies and stability. The effects of pitch link attachments in spanwise direction and chordwise direction as well as pitch link inclination on thrust, power, flpa-lag-pitch mode frequencies and inplane damping are examined. Pitch link at trailing edge location in chordwise direction has influence on aeroelastic stability of the rotor. Also, the pitch link with negative inclination angle makes inplane damping increase.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.167-167
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• 2004

반도체 공정 등에서 10-6_10-8 TOW의 고진공 환경을 제공하기 위하여 사용되는 고진공 터보분자펌프(Turbomolecular Pump, TMP)는 다층의 회전깃을 갖는 로터를 회전시켜 분자를 배출시키는 방식을 사용하는 진공펌프이다. 이러한 고진공을 실현하기 위해서는 가장 효과적인 방법으로는 회전블레이드의 선속도를 높이는 것으로, 이는 회전로터의 직경을 크게 하거나, 회전속도를 높임으로써 얻어질 수 있다. 따라서 최근의 고진공 터보분자펌프는 대부분 25,000∼40,000RPM의 고속회전을 요구하는 것이 일반적이며 회전속도는 주로 로터 재료의 허용한도까지 적용되고 있다.(중략)