• 유체기계공업학회:학술대회논문집
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• 1997.02a
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• pp.58-73
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• 1997

본 연구는 항공기용 환경제어계통의 시스템관련 제반 기술 및 그 핵심요소인 ACM(Air Cycle Machine)시제기의 개발을 통하여 국내의 여런 항공기개발 사업과 관련하여 급속히 요구되고 있는 항공기의 sub-system을 국산화할 수 있는 기술축적을 목적으로 수행되었다. 본 연구에서는 항공기용 환경제어장치(Environmental Control System : ECS)를 개발대상으로 하여 그 핵심부품인 Air Cycle Machine의 시제품을 순수 국내 기술로 설계/제작하였고, 자체 개발한 성능시험기를 이용하여 성능시험을 수행하였으며 또한 ACM 성능을 검증하기 위하여 기존제품의 자료와 비교하였다. 향후 이 시스템의 상품화를 위해서는 구동축의 무윤활 베어링에 대한 연구가 병행되어 주유동의 오일오염을 국소화시키는 시스템보완이 요구된다. 항공기용 환경제어장치(ECS)의 시스템해석부터 ACM의 공력/구조설계, 제작, 시험등 일련의 개발과정을 통하여 시스템에 대한 해석능력이 향상되었고, 그 핵심요소인 ACM의 순수 국산화개발이 가능하다는 판단을 내릴 수 있었다. 또한, ACM을 구성하고 있는 원심압축기와 반경류형 터빈의 제작 및 시험법은 유사 시스템 및 일반 터보기계류의 국산화개발에 유용하게 이용될 것으로 기대된다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.1
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• pp.255-265
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• 1996

Up to the present the study on the performance prediction of HAWT was performed mainly by assuming the axial flow. So in this paper we aimed at the fully non-axial flow of HAWT. For this purpose, we defined the wind turbine pitch angle in addition to the yaw angle to specify the arbitrary wind direction. And we adopted the Glauert method as the basic analysis method then modified this method suitably for our goal. By comparing the computational results obtained by this modified new Glauert method with the experimental results, it was proved that our method was a very efficient method. And on the basis of the reliability of this method we considered the effect of all the design parameters and presented the optimum blade geometry and the optimum operating condition to gain the best performance curve.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.315-318
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• 2006

포항풍력에너지연구소에서는 에너지 관리공단의 지원으로 2004년부터 풍력터빈 KBP-2000M에 사용될 발전기를 개발해 오고 있다. KBP-2000M에 사용되는 발전기는 기어비가 24인 기어박스를 가진 가변속도형식의 발전기이다. 발전기의 직경은 1.87m 이고 축 방향의 길이는 1.288m 로 영구자석을 사용하여 여자하는 형식으로 설계되었다. 이러한 설계는 풍력발전기에서 요구하는 주요 요구조건인 고효율, 고 신뢰성을 만족시키기 위해서 매우 중요하다 이 보고에서는 발전기의 물리설계에서 얻어진 사양을 기준으로 하여 열 해석에서 얻어진 열 손실을 이용하여 냉각시스템 설계를 하였으며 펌프 및 라디에이터 선정에 관해서 논의한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.593-598
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• 2000

In this paper the critical speed analysis and design sensitivity investigation are carried out with an APU(auxiliary power unit) gas turbine having a spline shaft connection. The DDM(direct differential method) is directly applied to formulate the critical speed design sensitivity problem of a general nonsymmetric-matrix rotor-bearing system. The design sensitivity analysis have shown that the critical speed change rate to the support modeling of the spline shaft connection point is extremely negligible, and thereby its design uncertainty is lifted. It has also been confirmed that the critical speeds up to the 4th are not sensitive to the design stiffness coefficients of 4-main bearings or supports, including two air foil bearings. Further, the critical speed change rate to the shaft-element length have shown quantitatively that the spline shaft has some limited influence on the 4th critical speed.

• New & Renewable Energy
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• v.8 no.1
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• pp.44-51
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• 2012

Due to a high tidal range of up to 10 m on the west coast of Korea, numerous tidal current projects are being planned and constructed. The turbine, which initially converts the tidal energy, is an important component because it affects the efficiency of the entire system. Its performance is determined by design variables such as the number of blades, the shape of foils, and the size of a hub. To design a turbine that can extract the maximum power on the site, the depth and duration of current velocity with respect to direction should be considered. Verifying the performance of a designed turbine is important, and requires a circulating water channel (CWC) facility. A physical model for the performance test of the turbine should be carefully designed and compared to results from computational fluid dynamics (CFD) analysis. In this study, a horizontal axis tidal current turbine is designed based on the blade element theory. The proposed turbine's performance is evaluated using both CFD and a CWC experiment. The sealing system, power train, measuring devices, and generator are arranged in a nacelle, and the complete TCP system is demonstrated in a laboratory scale.

• Journal of the Korean Society of Visualization
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• v.18 no.2
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• pp.59-65
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• 2020

Vertical axis wind energy systems including 3 and 4 blades are numerically investigated in a two-dimensional (2D) computational domain. The power coefficient (C_p) is adopted to measure the efficiency of the system and the effect of the rotating velocity on the power coefficient is analyzed for the two different systems. The rotating velocity varies from 30 rad/s to 90 rad/s, which corresponds to the tip speed ratio (T.S.R) of 0.5 to 1.5. The torque exerted on the blades is mainly determined by the aerodynamic force in the x-direction and maximized when the blade is positioned at around θ = 186°. The efficiency of the 4-blade system is higher than that of the 3-blade system within the tip speed ratio range between 0.5 and 0.67, besides where the 3-blade system shows a better performance. For the 3-blade system, the maximum efficiency is reached to 0.082 at the tip speed ratio of 1.083. The maximum efficiency of the 4-blade system is 0.071 at T.S.R. = 0.92. The velocity fields in the x-direction, pressure fields, and the vorticity magnitude are analyzed in detail for the optimal cases of the 3- and 4-blades systems, respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.4
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• pp.275-280
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• 2007

A turbine stage consists of stators and rotors. The stator provides the required inlet flow conditions so that the rotor can produce the necessary power. Passing wakes generated from the trailing edge of the stator make an interaction with the rotor. In the present study, this flow mechanism is investigated using the numerical analysis. In case of a large gap distance between the stator and rotor, the flow can be solved independently. First, only the stator flow field is solved. Second, the rotor flow field is solved including the passing wake characteristics obtained from the stator analysis. The passing wake experiences the shearing as it approaches to the rotor blade leading edge. And it is chopped when it strikes the rotor blade. After that, the chopped wakes becomes the prolongation as it travels downstream. The flow according to the variation of the gap distance is also studied. Pressure jumps due to the passing wakes result in the pressure and lift loss and it gets stronger with the closer gap distance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.686-686
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• 2013

Automotive turbochargers have become common in gasoline engines as well as diesel engines. They are excellent devices to effectively increase fuel efficiency and power of the engines, but they unfortunately cause several noise problems. The noises are classified into mechanical noises induced from movement of a rotating shaft and aerodynamic noises by air flow in turbochargers. In addition to, there is a mechanical noise caused from movement of an actuator, electronically controlling a wastegate valve. It is called as valve rattle noise. The actuator is connected to a valve through a linkage. The noise occurs only if the valve is open, where the linkage is freely contact to neighbor structures without being constrained by any external forces. This condition allows impacts by the pulsation of exhaust gas, and the vibration from the impacts spreads out through turbine housing, causing the rattle noise. The noise is not in mechanical operating wastegate turbochargers because the linkage of an actuator is strongly connected by actuating force. For the electronic wastegate turbocharger, this paper proposed a test device to show the noise generating mechanism with a small vibration motor having an unbalanced shaft. It also shows how to reduce the noise - reduction of linkage clearances, inserting wave washers into a connection, and applying loose fitting in bushing embracing a valve lever to turbine housing.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.4
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• pp.100-108
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• 2006

Experimental study has been a general way to evaluate inlet and exhaust duct performances, but this is not only costly but also time consuming. Computational simulation is hence replacing experimental study and consequently time and cost saving. This paper therefore aims to investigate typical component performance of the intake and exhaust ducts using 3D representation. In this study a specific inlet and exhaust was modeled and analyzed to estimate its losses and flow field using computational fluid dynamic program with flow visualization capabilities. A process that requires geometry data to be modeled. That allowed for possibility of design trade off in designing phase. Installed performance of a specific turbo shaft engine was finally evaluated with the estimated inlet, exhaust and other accessories losses.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.6
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• pp.365-372
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• 2013

In this study, the flow characteristics and structural safety of a 500W class vertical-axis wind turbines(VAWT) for a fishing boat are investigated by numerical simulations. Guide vanes to increase the performance of the VAWT are investigated. And the best guide vane in the numerical simulations is applied to the VAWT. Also, modal analyses are performed to find out the natural frequencies of the VAWT, and the resonance safety of the VAWT is evaluated. The structural analysis of the VAWT is carried out by one-way FSI(Fluid Structure Interaction). And the results are used for the evaluation of structural safety according to IEC 61400-1 code. Finally, the possibility of the installation of the VAWT on the wheelhouse of a 9.77ton class fishing boat is checked. The results of the present research could be used as one of the fundamental data to design a VAWT for a fishing boat.