• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.415.2-415.2
• /
• 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
• /
• 제12권6호
• /
• pp.829-834
• /
• 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
• /
• 제30권4호
• /
• pp.325-338
• /
• 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
• /
• 제43권2호
• /
• pp.122-129
• /
• 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.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2006년도 추계학술대회 논문집
• /
• pp.821-831
• /
• 2006

There are 5 railway bridges in a Seoul metro network; Jamsil, Dangsan(line 2), Dongho(line 3), Dongjak(line 4) and Chungdam(line 7). Because there are strong wind and vibration in the bridges, uplift of a contact wire caused by pantographs in the bridge section is higher than in a normal section. If the uplift at the support point exceed 10 cm, an interference between pantographs and catenary system happens. Estimated maximum uplift is obtained by applying safety factor 2 to the simulation results. The application of the safety factor is needed for taking into account of the effect of the wind, etc. Previously, we can not check whether or not the safety factor is proper. Recently, we can measure the uplift during the train operation, as a telemetry system which can measure dynamic behavior of the contact wire has been developed. The aim of this research is to review how proper the safety factor related to the uplift is, based on the measurement. We performed simulations and experiments for the uplift at the Jamsil railway bridge. The simulations were performed for the every kind of the train passing the Jamsil bridge. In order to compare the analysis results with the measurement results, we measured the uplifts at the support when the trains passed the measuring point. Finally, we proposed adequate safety factor with the uplift for the bridge section.

• Journal of Advanced Marine Engineering and Technology
• /
• 제38권3호
• /
• pp.262-268
• /
• 2014

본 연구는 2MW급 풍력 발전기용 고속커플링의 요구조건인 유연성과 절연성 및 과부하시 기능부품의 파손을 방지하기 위한 동력 차단기능을 만족하기 위한 구조설계와 검증에 관한 것이다. 커플링의 유연성과 절연기능은 강도와 유연성 및 절연성을 동시에 가지는 유리섬유강화플라스틱을 이용하여 설계하였으며 유한요소해석을 통하여 원소재 두께를 최적화하였다. 또한 이상 토크 발생시 동력전달을 차단하기 위한 토크리미터를 마찰차 형식으로 설계하였다. 시제품의 성능평가를 통하여 설계변수의 타당성을 검증하였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2011년도 추계학술대회 논문집
• /
• pp.843-848
• /
• 2011

Planning and construction of railway for high speed trains up to 400 km/h are recently driven in Korea. High speed train is one of the environment-friendly fastest mass transportation means but its noise generated by rolling, traction and aerodynamic mechanism can cause public complaints of residents nearby railways. To cost-effectively prevent the troublesome noise in a railway planning stage, the rational railway noise prediction method considering the characteristics of trains as well as railway structures should be required but it is difficult to find authentic methods for Korean high speed trains such as KTX and KTX-II. In this study, we propose a framework of our own railway noise prediction model emitted by Korean high speed trains over 250 km/h based on the recent research results carried out in EU countries. The model considers railway sound power level using several point sources distributed in heights as well as tracks, whose detail speed- and frequency-dependent emission characteristics of Korean high speed trains should be determined in near future by measurement or numerical analysis. The attenuation during propagation outdoors is calculated by the well-known ISO 9613-2 and auxiliary methods to consider undulated terrain and wind effect.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2008년도 춘계학술대회 논문집
• /
• pp.2224-2229
• /
• 2008

High-Speed train has been developed and it becomes faster and environmental friendly. As trains run faster, Noise of trains is generated mainly by aerodynamic disturbance. Pantograph, both ends of trains, and gaps of coaches which are thought to be aerodynamic noise's factors are primarily studied. Pantograph is a similarly shaped metal framework on the roof of an electric high speed train, transmitting current from an overhead electric catenary wire. Panhead which contacts electric wires directly looks like a bluff strut, goes through flows, is sensitive to external disturbances and is one of the most important factors which decide whole vehicles' driving ability. In this study, aerodynamically robust optimized pantograph panhead shape is designed and then evaluated through subsonic wind tunnel test. To compare these with existing panhead rectangular shapes or circular cylinder shapes, By visualizing strong vortex flow patterns which are main noise sources, characteristics are compared and analyzed

• 한국유체기계학회 논문집
• /
• 제20권1호
• /
• pp.35-40
• /
• 2017

In order to investigate the change of contact force of pantograph pan head due to the change of aerodynamic force, three dimensional flow around the pan head were calculated. For this, the aerodynamic modeling of pan head of CX pantograph was performed and the standard deviation of the contact force of the simulation results were compared with those of the experimental results of wind tunnel tests. From the comparison, it was confirmed that the current grid system and the numerical methodologies can be utilized to calculate the aerodynamic characteristics of the pantograph pan head. By using these grid system and the methodologies, the standard deviations of the contact force of pan head were calculated with velocities as 200, 250, 300, 350, and 400 km/h. The maximum standard deviation of the aerodynamic contact force of pan head was 92 N at 400 km/h and statistical minimum contact force was more than 0 N. Therefore, it was confirmed that and the pan head of CX pantograph was statistically contacted with the catenary system with the train speed of 350 km/h though the aerodynamic contact force was changed.

• International Journal of Computer Science & Network Security
• /
• 제22권3호
• /
• pp.220-228
• /
• 2022

The directed tests produce an expectation model to assist the organization's heads and professionals with settling on the right and speedy choice. A directed deep learning strategy has been embraced and applied for SCADA information. In this paper, for the load shedding expectation overall power organization of Libya, a convolutional neural network with multi neurons is utilized. For contributions of the neural organization, eight convolutional layers are utilized. These boundaries are power age, temperature, stickiness and wind speed. The gathered information from the SCADA data set were pre-handled to be ready in a reasonable arrangement to be taken care of to the deep learning. A bunch of analyses has been directed on this information to get a forecast model. The created model was assessed as far as precision and decrease of misfortune. It tends to be presumed that the acquired outcomes are promising and empowering. For assessment of the outcomes four boundary, MSE, RMSE, MAPE and R2 are determined. The best R2 esteem is gotten for 1-overlap and it was 0.98.34 for train information and for test information is acquired 0.96. Additionally for train information the RMSE esteem in 1-overlap is superior to different Folds and this worth was 0.018.