• 한국소음진동공학회논문집
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• 제25권8호
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• pp.553-558
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• 2015

This paper aims at making a dedicated vibration monitoring and diagnosis framework for 3MW WTG(wind turbine generator). Within the scope of the research, vibration data of WTG drive train are used and WTG operating conditions are involved for dividing the vibration data class which included transient and steady state vibration signals. We separate two health detections which are CHD(continuous health detection) and EHD(event health detection). CHD has function of early detection and continuous monitoring. EHD makes the use of finding vibration values of fault components effectively by spectrum matrix subsystem. We proposed framework and showed application for 3MW WTG in a practical point of view.

• Wind and Structures
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• 제29권3호
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• pp.149-161
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• 2019

When a railway vehicle runs in crosswinds, the unsteady aerodynamic forces acting on the train induced by the vehicle speed, crosswind velocity and local landforms are a common problem. To investigate the dynamic performance of a railway vehicle due to the influence of unsteady aerodynamic forces caused by local landforms, a vehicle aerodynamic model and vehicle dynamic model were established. Then, a wind-loaded vehicle system model was presented and validated. Based on the wind-loaded vehicle system model, the dynamic response performance of the vehicle, including safety indexes and vibration characteristics, was examined in detail. Finally, the effects of the crosswind velocity and vehicle speed on the dynamic response performance of the vehicle system were analyzed and compared.

• 한국해양공학회지
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• 제37권4호
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• pp.164-171
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• 2023

Vibration and noise must be considered to maximize the efficiency of a yaw system and reduce the fatigue load acting on a wind turbine. This study investigated a method for analyzing yaw-system vibration based on the change in the load-duration distribution (LDD). A substructure synthesis method was combined with a planetary gear train rotational vibration model and finite element models of the housing and carriers. For the vibration excitation sources, the mass imbalance, gear mesh frequency, and bearing defect frequency were considered, and a critical speed analysis was performed. The analysis results showed that the critical speed did not occur within the operating speed range, but a defect occurred in the bearing of the first-stage planetary gear system. It was found that the bearing stiffness and first natural frequency increased with the LDD load. In addition, no vibration occurred in the operating speed range under any of the LDD loads. Because the rolling bearing stiffness changed with the LDD, it was necessary to consider the LDD when analyzing the wind turbine vibration.

• 조명전기설비학회논문지
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• 제18권2호
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• pp.142-149
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• 2004

본 논문은 바람으로부터 최대출력을 추출하기 위해 계통연계 풍력발전시스템의 신경회로망 제어기와 추출된 최대출력을 계통에 전달하기 위한 전력제어기를 제안한다. 유도발전기, 변압기, 정류기 및 인버터 등으로 구성된 제어기를 갖춘 풍력발전시스템의 모델링과 시뮬레이션에 대해 검토하고자 한다. 본 논문에서는 동특성해석을 위해 드라이브 트레인 모델, 유도발전기 모델과 계통접속 모델을 제시한다. 신경회로망 제어기는 풍차날개의 피치각을 제어하여 바람으로부터 최대출력을 추출한다. 피치제어방법은 기계적으로 복잡하지만 제어성능은 스톨제어보다 우수하게 된다. MATLAB으로 수행한 시뮬레이션 결과는 발전기 토오크, 발전기 회전속도, 피치각, 계통으로 주입되는 유효/무효전력 등을 예시하고 있으며 그 결과를 보면 제안된 제어기의 효용성을 입증할 수 있다.

• Wind and Structures
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• 제25권1호
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• pp.63-77
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• 2017

When railway vehicles run by towers of long span bridges, the railway vehicles might experience a sudden load-off and load-on phenomenon in crosswind conditions. To ensure the running safety of the railway vehicles and the running comfort of the passengers, some studies were carried out to investigate the impacts of sudden changes of aerodynamic loads on moving railway vehicles. In the present study, the aerodynamic coefficients which were measured in wind tunnel tests using a moving train model are converted into the aerodynamic coefficients in the actual scale. The three-component aerodynamic loads are calculated based on the aerodynamic coefficients with consideration of the vehicle movement. A three-dimensional railway vehicle model is set up using the multibody dynamic theory, and the aerodynamic loads are treated as the inputs of excitation varied with time for kinetic simulations of the railway vehicle. Thus the dynamic responses of the railway vehicle passing by the bridge tower can be obtained from the kinetic simulations in the time domain. The effects of the mean wind speeds and the rail track positions on the running performance of the railway vehicle are discussed. The three-component aerodynamic loads on the railway vehicle are found to experience significant sudden changes when the vehicle passes by the bridge tower. Correspondingly, such sudden changes of aerodynamic loads have a large impact on the dynamic performance of the running railway vehicle. The dynamic responses of the railway vehicle have great fluctuations and significant sudden changes, which is adverse to the running safety and comfort of the railway vehicle passing by the bridge tower in crosswind conditions.

• 한국철도학회논문집
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• 제15권1호
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• pp.17-22
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• 2012

스크린 도어는 승강장에 설치하여 차량운행에 의한 승객의 안전을 확보하고, 승강장 내 공기질을 확보를 통한 쾌적함을 유지하며, 냉난방 에너지를 줄임으로써 다양한 효용성을 확보하고 있다. 이러한 스크린 도어의 안정성을 확보하기 위해서는 내풍압 평가를 고려한 설계가 필요하다. 본 연구에서는 승강장 스크린 도어의 내풍압을 예측하기 위하여 소사역사, 반밀폐형 스크린 도어, 전동차를 모델링하고 해석을 수행하였다. 또한 소사역은 지상역으로 외부에 노출되어 있기 때문에 기후조건에 영향을 받게 된다. 따라서 최악의 기후조건인 태풍의 영향을 고려하여 해석을 수행하였다. 해석결과, 최대 내풍압은 287 Pa이고, 외풍압을 고려한 최대압력은 865 Pa로 설계조건은 2756.25 Pa보다 약 3.1배 차이로 안정성이 확보됨을 알 수 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.415.2-415.2
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• 2016

Triboelectric nanogenerator (TENG) is one of ways to convert mechanical energy sound, waves, wind, vibrations, and human motions to available electrical energy. The principal mechanism to generate electrical energy is based on contact electrification on material surface and electrostatic induction between electrodes. The performance of TENG are dependent on amount of the input mechanical energy and characteristics of triboelectric materials. Furthermore, the whole TENG system including mechanical structure and electrical system can effect on output performance of TENG. In this work, we investigated the effect of gear train on output performance and power conversion efficiency (PCE) of TENG under a given input energy. We applied the gear train on mechanical structure to improve the contact rate. We measured the output energy under a constant input energy by controlling the size of the working gear. We prepared gears with gear ratios (rin/rw) of 1, 1.7, and 5. Under the constant input energy, the voltage and current from our gear-based TENG system were enhanced up to the maximum of 3.6 times and 4.4 times, respectively. Also, the PCE was increased up to 7 times at input frequency of 1.5 Hz. In order to understand the effect of kinematic design on TENG system, we performed a capacitor experiment with rectification circuit that provide DC voltage and current. Under the input frequency of 4.5 Hz, we obtained a 3 times enhanced rectifying voltage at a gear ratio of 5. The measured capacitor voltage was enhanced up to about 8 fold in using our TENG system. It is attributed that our gear-based TENG system could improve simultaneously the magnitude as well as the generation time of output power, finally enhancing output energy. Therefore, our gear-based TENG system provided an effective way to enhance the PCE of TENGs operating at a given input energy.

• 한국철도학회논문집
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• 제12권6호
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• pp.829-834
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• 2009

자갈비산에 대한 위험성을 평가하는 한 방법으로 열차 하부 각 지점에서 다양한 자갈 종류 및 열차 속도에 따라 자갈 비산 확률을 파라메타로 제시하였다. 이를 위하여 풍동실험 결과를 바탕으로 한 확률계수 BFPF를 이용하였으며, 다양한 조건의 열차 하부 영역에 대한 수치해석을 수행하여 각 조건에 따른 각 지점의 자갈비산확률을 검토하였다. 열차 속도증가에 따라 비산확률이 급격히 증가하고, 속도가 350 km/h가 되면 자각비산 확률이 87%로 증가하였다. 또한 높힘침목을 적용하였을 경우와 비교를 통해, 다양한 조건에서의 자갈비산 확률에 대한 민감도를 분석하여 자갈형태 및 높힘침목 형태에 따른 변화 특성을 분석하고 높힘침목이 자갈비산 위험을 억제할 수 있음을 확인하였다.

• Wind and Structures
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• 제30권4호
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• pp.325-338
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• 2020

In this paper, the improvement of the anti-snow performance of a high-speed train (HST) is studied using the unsteady Reynolds-Averaged Navier-Stokes simulations (URANS) coupled with the Discrete Phase Model (DPM). The influences of the proposed flow control scheme on the velocity distribution of the airflow and snow particles, snow concentration level and accumulated mass in the bogie cavities are analyzed. The results show that the front anti-snow structures can effectively deflect downward the airflow and snow particles at the entrance of the cavities and alleviate the strong impact on the bogie bottom, thereby decrease the local accumulated snow. The rotational rear plates with the deflecting angle of 45° are found to present well deflecting effect on the particles' trajectories and force more snow to flow out of the cavities, and thus significantly reduce the accretion distribution on the bogie top. Furthermore, running speeds of HST are shown to have a great effect on the snow-resistance capability of the flow control scheme. The proposed flow control scheme achieves more snow reduction for HST at higher train's running speed in the cold regions.

• 한국환경보건학회지
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• 제43권2호
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• pp.122-129
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• 2017

Objectives: Most of the $PM_{10}$ in subway stations is spread by the train-induced wind from the tunnels. Therefore, in order to improve air quality in subway stations, it is important to remove the $PM_{10}$ from the tunnels. After the installation of PSD (platform screen doors), the influence of train-induced wind and $PM_{10}$ at the platform has decreased, but is estimated to have increased in subway tunnels. This study was conducted to investigate the control of $PM_{10}$ in subway tunnels by applying a 500-fold diluted solution mixed with a humectant using a natural polymer. Methods: For this purpose, we tested the dust reduction effect in a laboratory and corrosion test and water pollution using fish and aquatic plants for the natural dust collecting agent. In the tunnel of a subway station, we used the natural dust collecting agent over 15 days. The study was carried out on $PM_{10}$ control during operation, which accounts for more than 70% of subway dust. Results: As results, the natural dust collecting agent exhibited an excellent dust control effect, and it was safe for water quality and soil. It showed the effect of controlling $PM_{10}$ in the subway tunnel by 49.5- 64.7% over 15 days. The use of the dust collecting agent for the control of $PM_{10}$ could be confirmed in the subway. Conclusion: It is necessary to clearly explain the major portions of chemical components contained in $PM_{10}$ to figure out the characteristics of $PM_{10}$ and to develop effective reduction measures to decrease the adverse effects of $PM_{10}$ in the subway.