• Journal of the Korean Society of Industry Convergence
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• 제22권6호
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• pp.711-719
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• 2019

At present, wind power is the fastest growing technology in the world. The domestic market depends heavily on imports for wind tower lift. so it manage through the overseas maker. The lift manufacture, establishment and maintenance utility is increasing, localization development of one wind tower lift is necessary with domestic fundamental base technique. In this paper, we will study the components necessary for the development of onshore offshore wind tower elevators, which are currently dependent on total imports, in line with the high growth of the wind market and the enlargement of the wind power generators. First of all, endless winders and cabins, which are the core components of the offshore wind tower lift, were examined for the components that affect the structural safety. Structural analysis was performed on Sheave, which is responsible for most of the lift lifting loads, and Block Stop, a safety device that prevents the cabin from falling in an emergency. The structural suitability was evaluated by comparing with the safety factor. In addition, the on-board control panel combines the control panel of the elevator and the drive motor driving the endless winder for efficient control of the offshore wind tower lift. The addition of features improves ride comfort at departure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제42권1호
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• pp.59-66
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• 2014

In the case of a propeller-driven aircraft, power-on effect generated by the propeller has a strong influence on the performance and the stability of an aircraft directly and indirectly. A numerical study on the power-on effect has been performed using the CFD based on the multiple reference frame and sliding mesh model. The power-on effect increases the overall lift and the maximum lift of the aircraft. In addition to lift increment, power-on effect delays the stall of the aircraft. On the other hand, the power-on effect increases the drag significantly and consequently decreases the lift-to-drag ratio of the aircraft. Furthermore, the power-on effect decreases the nose-down pitching moment and consequently decreases the longitudinal static stability of the aircraft. It is expected that the analysis results presented and discussed in this report will be used as an important material for analyzing the aircraft performance and stability and will contribute the development of the propeller-driven aircraft with the pusher propeller.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.969-970
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.637-638
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• 2010

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제22권11호
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• pp.1125-1132
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• 2011

The purpose of this study is to suggest installation methods of a mobile-communication repeater into a lift system with consideration of EMC. Two approaches, one(Solution 1) is realized with a repeater installed in a lift hoistway and another(Solution 2) installed inside a lift, were proposed. It is confirmed that the Solution 1 is more effective than the Solution 2. And it is suggested that the EIRP of a repeater must be limited to be ${\leq}$-5 dBm by considering electromagnetic immunity level for a lift and safety margin of 20 dB. This limit can provide suitable electromagnetic environment inside a lift with precise power-control mechanism of mobile communication systems. This study could be a good example of Green ICT by improving electromagnetic environment in spite of radio use.

• Journal of Ocean Engineering and Technology
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• 제11권1호
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• pp.55-64
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• 1997

A wing operating in close proximity to the ground exhibits a reduction in induced drag, which increase the lift/drag ratio. The poert-augmented ram (RAR) phenomenon involves directiing the efflux from forward mounted propulsion ststem under the wings, with the efflux nearly stagnated under the wings. In the present paper, 3 dimentional PAR was numerically studied by solving the Navier-Stokes equations. Pressure distribution and velocity vectors are calculated around the wing surface and the ground. Through the numerical simulation, Cp values and lift/drag ratio are carefully reviewed by changing the height/chord; 0.05, 0.1, 0.3 and 0.8. The shape of model is NACA 0012 with a span/chord ratio of 3.0. According to the numerical results, the relationship between lift/drag and height/chord is fairly reasonable.

• Journal of Advanced Marine Engineering and Technology
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• 제28권5호
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• pp.847-852
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• 2004

The wind turbine blade is the equipment converted wind into electric energy. The effect of the blade has influence of the output power and efficiency of wind turbine. The design of blade is considered of lift-to-drag ratio. structure. a condition of process of manufacture and stable maximum lift coefficient, etc. This study is used the simplified method for design of the aerodynamic blade and aerodynamic analysis used blade element method This Process is programed by delphi-language. The Program has any input values such as tip speed ratio blade length. hub length. a section of shape and max lift-to-drag ratio. The Program displays chord length and twist angle by input value and analyzes performance of the blade.

• Proceedings of the KIEE Conference
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.913-914
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• 2006

In industrial field, electric fork-lift has been mainly powered by batteries which are varied from DC 36V to 80V. Operating electric fork-lift truck depends on stable electric power supplies which are ensured by using Switched Mode Power Supply (SMPS). This paper presents design of SMPS for stable electric power supply. The SMPS has much strength such as high effectiveness, low cost and high stability of output voltage. At the same time, SMPS is small and multi output and has simple design of circuit.

• Proceedings of the KSME Conference
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• 대한기계학회 2008년도 추계학술대회A
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• pp.762-767
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• 2008

Estimated values for maximum lift coefficients of a light airplane, ChanGong-91, derived from an analytical method using a test database, a computational fluid dynamic method, a wind tunnel test, and a flight test are compared. The DATCOM method and VSAERO code are applied as the analytical method and the computational fluid dynamic method, respectively, in order to estimate the maximum lift coefficients of a light airplane. The wind tunnel test is conducted using a 1/14.5 scaled model installed in a closed circuit type wind tunnel. For the flight test approach, the wings-level power-off stall tests are performed to obtain the maximum lift coefficients. As a point of reference for the flight test results of the maximum lift coefficients, the differences of both estimates derived from the DATCOM method and the wind tunnel test data are smaller than those derived from VSAERO.

• Journal of the Korean Crystal Growth and Crystal Technology
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• 제27권2호
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• pp.75-79
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• 2017

Honeycomb-shaped Ag-grid transparent conductive electrodes (TCEs) were fabricated using two different processes, high density plasma etching and lift-off, and the optical and electrical properties were compared according to the fabrication method. For the fabrication of the Ag-grid TCEs by plasma etching, etch characteristics of the Ag thin film in $10CF_4/5Ar$ inductively coupled plasma (ICP) discharges were studied. The Ag etch rate increased as the power increased at relatively low ICP source power or rf chuck power conditions, and then decreased at higher powers due to either decrease in $Ar^+$ ion energy or $Ar^+$ ion-assisted removal of the reactive F radicals. The Ag-grid TCEs fabricated by the $10CF_4/5Ar$ ICP etching process showed better grid pattern transfer efficiency without any distortion or breakage in the grid pattern and higher optical transmittance values of average 83.3 % (pixel size $30{\mu}m/line$ width $5{\mu}m$) and 71 % (pixel size $26{\mu}m/line$ width $8{\mu}m$) in the visible range of spectrum, respectively. On the other hand, the Ag-grid TCEs fabricated by the lift-off process showed lower sheet resistance values of $2.163{\Omega}/{\square}$ (pixel size $26{\mu}m/line$ width $18{\mu}m$) and $4.932{\Omega}/{\square}$ (pixel size $30{\mu}m/line$ width $5{\mu}m$), respectively.