• 한국유체기계학회 논문집
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• 제3권3호
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• pp.31-40
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• 2000

A computer program is developed for the prediction of the aerodynamic performance and the noise characteristics in the basic design step of axial flow fan. The flow field and the performance of fan are analyzed by using the streamline curvature computing scheme with total pressure loss and flow deviation models. Fan noise is assumed to be generated due to the pressure fluctuations induced by wake vortices of fan blades and to radiate via dipole distribution. The vortex-induced fluctuating pressure on blade surface is calculated by combining thin airfoil theory and the predicted flow field data. The predicted performances, sound pressure level and noise directivity patterns of fan by the present method are favorably compared with the test data of actual fan. Furthermore, the present method is shown to be very useful in optimizing design variables of fan with high efficiency and low noise level.

• 제어로봇시스템학회논문지
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• 제20권9호
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• pp.922-929
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• 2014

Wind turbines are in the limelight in the alternative energy industry. However, they face frequent and various problems during operation. We focused on the supervising of the blades of a wind turbine. In this paper, we present the design of a maintenance robot that takes the size of wind turbine blades into consideration, so the general form of the robot is a square with four wires fixed to its vertices and to the nacelle. After the robot is placed near the nacelle, it moves along the blades. We also designed an attitude control algorithm for the robot to maintain its balance. Our control algorithm for the robot consists of roll and pitch attitude controllers and a height controller. Each controller was designed independently and then superposed together. We used simulations to verify our control algorithm.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.168-169
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• 2005

The optimum design and the performance analysis software called POSEIDON for the HAWT (Horizontal Axis Wind Turbine) was developed by use of BEMT. The Prandtl's tip loss theory was adopted to consider the blade tip loss. The lift and the drag coefficient of S-809 airfoil were predicted via X-FOIL and also the post stall characteristics of S-809 were estimated by the Viterna's equations. All the predicted aerodynamic characteristics are fairly well agreed with the wind tunnel test results, performed by Sommers in Delft university of technology. The rated power of the testing rotor is 20kW(FIL-20) at design conditions. The experimental aerodynamic parameters and the X-FOIL data were used for the power prediction of the FIL-20 respectively. The comparison results shows good agreement in power prediction.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.2076-2082
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• 2003

A cross-flow fan is widely used on many industrial fields: mining industry, automobile and home appliances, etc. The design point of the cross-flow fan is generally based on the region within low static pressure and high flow rate. It relatively makes high dynamic pressure at low speed because a working fluid passes through an impeller blade twice. However, it has low static pressure efficiency between 30% and 40% because of relative high impact loss. Recently, in the air-conditioning systems, the operating behaviors at the off-design points are highly regarded to broaden the application area for various air-cooling loads. Especially, at the lower flow rate, there exists a rapid pressure head reduction, a noise increase and an irregular flow field against a rearguider as a scroll of centrifugal fan. Numerical analyses are carried out for investigating the flow characteristics in a cross-flow fan including the impeller, the rearguider and the stabilizer. Especially, various types of rearguiders are estimated by numerical and experimental methods to insure the stable operation in the region of lower flow rate. Numerical domains are discretized by hexahedral cells. Three-dimensional, unsteady governing equations are solved using FVM, PISO algorithm, sliding grid system and standard ${\kappa}-{\varepsilon}$ turbulence model. ASHRAE standard fan tester is also used to estimate the performance of the modeled crossflow fan.

• 한국기계가공학회지
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• 제14권5호
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• pp.1-7
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• 2015

Cleaning by injecting dry ice and water is a generally adopted trend these days to clean molds (injection, diecasting foundry, press, rubber mold, etc). This cleaning method is performed manually, or by installing multiple high pressure spray nozzles. We have manufactured a turbine cleaning module device that is able to clean diecasting modules at any position and angle in the space by mounting an articulated robot instead of the existing pipe type injection nozzle, to minimize lead time and enhance working yield of the cleaning process. In this paper, we analyzed process factors that are required to design the turbine module by reviewing number of revolution, and results according to different blade angles and thicknesses of the mold release injection turbine module, using computational fiuid dynamics (CFD).

• 한국추진공학회지
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• 제7권4호
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• pp.19-26
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• 2003

본 논문에서는 팁제트 로터를 사용한 CRW 비행체의 추진시스템에 대한 개념연구 결과를 다루었다. 비행체 중앙에 위치한 엔진으로부터 배기가스를 로터나 주 추력노즐까지 공급하기 위해서 길고 복잡한 내부덕트 시스템이 필요하며 배기가스 분배장치 등이 필요하다. 추진시스템의 성능해석을 위해 엔진운전특성과 내부덕트 시스템 특성을 함께 해석하였다 본 연구에서는 회전익모드에서 내부덕트 시스템의 형상변화에 따른 엔진 및 전체 추진시스템의 운전특성을 분석하여 추진시스템 설계를 위한 중요설계변수를 도출하였으며 파라매트릭 연구를 수행하여 향후 설계방향설정에 기여하였다.

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.751-757
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• 2016

The present work discusses two different models of boiling water reactor (BWR) bundle to compare the neutronic characteristics of uranium dioxide ($UO_2$) and uranium zirconium hydride ($UZrH_{1.6}$) fuel. Each bundle consists of four assemblies. The BWR assembly fueled with $UO_2$ contains $8{\times}8$ fuel rods while that fueled with $UZrH_{1.6}$ contains $9{\times}9$ fuel rods. The Monte Carlo N-Particle Transport code, based on the Mont Carlo method, is used to design three dimensional models for BWR fuel bundles at typical operating temperatures and pressure conditions. These models are used to determine the multiplication factor, pin-by-pin power distribution, axial power distribution, thermal neutron flux distribution, and axial thermal neutron flux. The moderator and coolant (water) are permitted to boil within the BWR core forming steam bubbles, so it is important to calculate the reactivity effect of voiding at different values. It is found that the hydride fuel bundle design can be simplified by eliminating water rods and replacing the control blade with control rods. $UZrH_{1.6}$ fuel improves the performance of the BWR in different ways such as increasing the energy extracted per fuel assembly, reducing the uranium ore, and reducing the plutonium accumulated in the BWR through burnup.

• 신재생에너지
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• 제3권3호
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• pp.63-71
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• 2007

본 연구의 목적은 3차원 풍력터빈 블레이드 최적형상설계를 위한 실용적이고 효율적인 설계과정을 구현하는 것이다. 국내 연안의 해상풍력에 적용하기 위해서 통계적 모델을 이용하여 풍황자료를 분석하였다. 설계에 관련된 많은 수의 설계변수를 효과적으로 관리하기 위해서 설계과정은 운용조건 최적화와 블레이드 형상설계의 2단계로 구성하였다. 실험계획법에 의해 추출된 각 운용조건 설계점은 형상설계를 위한 입력 값으로 제공된다. 형상설계 단계에서는 최소에너지손실 조건과 결합된 BEMT를 이용하여 각 블레이드 단면에서의 시위길이와 피치각 분포를 최적화하였다. 블레이드 단면 익형은 NREL S830을 이용하였고, 익형의 공력성능은 XFOIL을 이용하여 예측하였다. 설계된 블레이드 형상의 성능해석을 수행하고 그 결과를 바탕으로 반응면을 구성하였다. 좀 더 나은 성능을 가진 블레이드 형상을 찾기 위해서 초기설계공간에서 확률적 방법을 이용하여 타당성 있는 설계공간까지 운용조건 설계변수를 이동시키고 구배최적화 기법을 통해 각각의 제약함수를 만족하면서 연간에너지생산량을 최대로 하는 최적블레이드 형상을 구현하였다. 제시된 최적설계과정은 풍력터빈블레이드 개발에 실용적이고 신뢰성 있는 설계툴로서 사용이 가능하다.

• Advances in concrete construction
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• 제9권5호
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• pp.459-467
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• 2020

Mechanical and thermal properties of composite sandwich wall panels are affected by changes in their external environment. Humidity and temperature changes induce stress on wall panels and their core connectors. Under the action of ambient temperature, temperature on the outer layer of the wall panel changes greatly, while that on the inner layer only changes slightly. As a result, stress concentration exists at the intersection of the connector and the wall blade. In this paper, temperature field and stress field distribution of UHPC-RW-RC (Ultra-High Performance Concrete - Rock Wool - Reinforced Concrete) wall panel under high temperature-sprinkling and heating-freezing conditions were investigated by using the general finite element software ABAQUS. Additionally, design of the connection between the wall panel and the main structure is proposed. Findings may serve as a scientific reference for design of high performance composite sandwich wall panels.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.236-239
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• 2011

This paper introduces the design concepts and characteristics of WinDS3000$^{TM}$(TC IIa) which is a trade name of Doosan's 3MW offshore/onshore wind turbine. WinDS3000$^{TM}$(TC IIa) has been designed in consideration of high Reliability, Availability, Maintainability and Serviceability (RAMS) and low cost of electricity (CDE) for the TC IIa condition based on GL guideline. An integrated drive-train design with an innovative three-stage gearbox has been introduced to minimize nacelle weight of the wind turbine and to enhance a high reliability for transmission. A permanent magnet generator with full converter system has been introduced to get higher efficiency in partial load operation and grid-friendly system for both 50 Hz and 60 Hz. A pitch-regulated variable speed control system has been introduced to control wind turbine power while generator reaction torque can be adjusted almost instantaneously by the associated power electronics. The wind turbine has been also equipped with condition monitoring and diagnostic systems in order to meet maintainability requirements.