• 에너지공학
• /
• 제12권4호
• /
• pp.309-319
• /
• 2003

본 논문의 목적은 가변속 풍력터빈이 배전망에 미치는 영향을 평가하기 위한 모의해석 모델을 제시하고 제시된 모델을 사용하여 배전망에서의 전력품질에 대한 모의해석을 수행하는 것이다. 모델링된 풍력발전 시스템은 고정피치각을 갖는 풍력터빈과 영구자석형 동기발전기로 구성되며 전력전자 인버터에 의해 가변속 운전 및 무효전력 출력제어가 이루어진다. 풍력터빈 연계에 의한 전압변동 및 고조파 문제를 언급하며, 그 영향에 대하여 제시한 모델을 사용하여 정상상태 및 동특성 해석을 수행한다. 다양한 용량과 다른 출력제어방식의 가변속 풍력터빈을 이용하여 모의하고 평가한다. 사례연구들을 통해 각기 다른 계통상태에서 풍속의 변동 및 다른 출력제어방식에 따른 배전망의 전압변동에 미치는 영향과 고조파 문제를 보여준다. 모델링 및 모의는 PSCAD/EMTDC 프로그램을 기반으로 하여 수행한다.

• 소음진동
• /
• 제10권2호
• /
• pp.306-311
• /
• 2000

The stress distribution of a rotating cantilever beam in transient vibration is investigated in this paper. The equations of motion of the rotating bean are derived and numerical results are obtained. The tensile and bending stresses which occur when the beam rotates with the tuned angular speed or passes through the tuned angular speed are obtained. Since those stresses are usually significant during the rotational motion, it is important to estimate them accurately in the design of the rotating structure.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 춘계학술대회 논문집
• /
• pp.78-81
• /
• 2002

To achieve high precision machine totals with high speed, it is needed to develop excellent rigidity statically, dynamically and thermally as well. In this view the chief things that thermal deformation of machine tool structure is directly related to high precision. And thermal behavior for transmission procedure have an effect on high precision. It is needed to exact temperature distribution of each members and all contact elements included for machine tool structure. This paper deals with thermal behavior caused by temperature variation in a high speed feeding process. At this procedure of temperature distribution is estimated using a Predictor-Corrector Method.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.351-354
• /
• 2005

Research purpose of this project is intending Maintenance Free of freight car and speed up of freight train. At goods transport as heightening traveling by ship speed of freight train shortening raise railway share of physical distribution and stand on tiptoe to Northeast Asia physical distribution main country to contribute expect. This paper is the performance elevation methods of next generation railway freight vehicles.

• 소성∙가공
• /
• 제15권5호
• /
• pp.366-372
• /
• 2006

The effect of coating time in arc ion plating on surface properties of the TiN-coated high speed steel(SKH51) is presented in this paper. Surface roughness, micro-hardness, coated thickness, atomic distribution of TiN and adhesion strength are measured for various coating times. It has been shown that the coating time has a deep influence on the micro-hardness, the coated thickness, the atomic distribution of Ti and the adhesion strength of the SKH51 steels but that it has little influence on the surface roughness.

• 한국환경과학회지
• /
• 제3권1호
• /
• pp.31-38
• /
• 1994

The diffusion of the pollutants released into atmosphere is dependent on its chemical reaction, topography and micrometeorological characteristics. The purpose of the study is to investigate how much micrometeorological characteristics such as stability, wind speed and mixing height affect the diffusion of the air pollutants. For this purpose, this paper let 1) the basic theory be K-theory, 2) eddy diffusivity and wind speed be dependent on mixing height and stability, and 3) Grout method be used for numeric calculation. The result was 1) the more unstable condition, the higher mixing height and the higher wind speed we, the lower pollutants concentration appears, 2) the most intensive effect on the distribution of the pollutant concentration is the atmospheric stability.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2006년도 춘계학술대회 논문집
• /
• pp.308-313
• /
• 2006

The effect of coating time on surface properties of the TiN-coated high speed steel(SKH51) by arc ion plating is and presented in this paper. Surface roughness, micro-hardness, coated thickness, atomic distribution of TiN and adhesion strength are measured for various coating times. It has been shown that the coating time has a deep influence more than 60 minites on the micro-hardness, coated thickness, atomic distribution of Ti and adhesion strength of the SKH51 steels, but that the coating time has little influence on the surface roughness.

• Korea-Australia Rheology Journal
• /
• 제18권3호
• /
• pp.143-151
• /
• 2006

We analyzed the non-Newtonian and non-isothermal flow in a single screw extruder system and investigated the mixing performance with respect to the screw speed and the screw pitch. The viscosity of polymer melt was described with Carreau-Yasuda model. The mixing performance was computed numerically by tracking the motions of particles in the screw element system. The extent of mixing was characterized in terms of the deformation rate, the residence time distribution, and the strain. The results revealed that the high screw speed reduces the residence time but increases the deformation rate while the small screw pitch increases the residence time. It is concluded that the high screw speed increases the dispersive mixing performance and the small screw pitch increases the distributive mixing performance.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 춘계학술대회 논문집
• /
• pp.1021-1026
• /
• 2000

The thermal characteristics of high-speed air spindle system with built-in motor are studied. Experiment and finite element method analysis obtain temperature rise and temperature distribution of housing. For the analysis three-dimensional model is built and temperature rise and distribution in thermal steady state are computed for each rotational frequency. Generally. It is said that the heat generation of air bearing is negligible. But it is certain that the heat generation of air bearing can not be negligible especially in high-speed conditions Frequency response test for air spindle system is executed. In case that the heat generation of air spindle system is high, natural frequency of the system becomes lower when it reaches thermal steady-state and it means that the stiffness of air hearing becomes smaller due to the change of bearing clearance. It is shown that the temperature rise of all spindle system causes thermal expansion md induces the variation of hearing clearance. In consequence the st illness of air bearing becomes smaller.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집A
• /
• pp.199-204
• /
• 2001

Big accidents of flyings, vessel, subways, gas equipments, buildings and bridge happens frenquently. Therefore many people are suffering harm of property. The destruction cause of macaine components is almost accused by fatigue. This study is test for STS304 specimen using pure and cantilever bending state. Rounded specimen and notched specimen including fracture surface investigation was comparatively experimented, fatigue life according to degree of surface finishing was examined. Fatigue fracture probability of notched canilever specimens were predicted by P-S-N curve, median rank and Weibull distribution. And at the relation with the rotational speed and stress, the fatigue life of the test specimen was higher at high speed than low speed.