• Title/Summary/Keyword: Train Separation

Search Result 46, Processing Time 0.022 seconds

The Effect of Scaling of Owl's Flight Feather on Aerodynamic Noise at Inter-coach Space of High Speed Trains based on Biomimetic Analogy

  • Han, Jae-Hyun;Kim, Tae-Min;Kim, Jung-Soo
    • International Journal of Railway
    • /
    • v.4 no.4
    • /
    • pp.109-115
    • /
    • 2011
  • An analysis and design method for reducing aerodynamic noise in high-speed trains based on biomimetics of noiseless flight of owl is proposed. Five factors related to the morphology of the flight feather have been selected, and the candidate optimal shape of the flight feather is determined. The turbulent flow field analysis demonstrates that the optimal shape leads to diminished vortex formation by causing separation of the flow as well as allowing the fluid to climb up along the surface of the flight feather. To determine the effect of scaling of the owl's flight feather on the noise reduction, a two-fold and a four-fold scaled up model of the feather are constructed, and the numerical simulations are carried out to obtain the aerodynamic noise levels for each scale. Original model is found to reduce the noise level by 10 dBA, while two-fold increase in length dimensions reduces the noise by 12 dBA. Validation of numerical solution using wind tunnel experimental measurements is presented as well.

  • PDF

Verification on Separation Distance Criteria when Transporting Dangerous Goods in Korea Railroad (국내 철도 위험물 운송 시 격리차 운영기준 안전성 검증)

  • Lee, Byeongwoo;Park, Dasung;Kang, Taesun;Jung, Seungho
    • Journal of the Korean Society of Safety
    • /
    • v.34 no.2
    • /
    • pp.28-33
    • /
    • 2019
  • After the Tianjin Port explosion on 2015, it is highlighted that securing safety for dangerous goods in Korea and try to establish safety standards for railroad dangerous substances transport. In Korea, the regulation for the transport of dangerous goods is stipulated to need 3 buffer cars. However, It is inefficient that 3 buffer cars. because 3 buffer cars, increase transportation too much costs in transit and it is too strict compared to other country rules. The purpose of this study was to improve transportation efficiency by mitigating the criteria for isolated railroads through rational safety assessment. In order to verify this, we used a risk assessment software which is PHAST 7.2 developed by DNV GL. We calculated safety distances that could prevent ignitions setting up scenarios when relief system work installed on a train loaded with propylene, nonane. As a result, we confirmed that buffer cars can be reduced from three to one. This result would be implemented in the application of Korail.

QUANTITATIVE MONITORING OF TISSUE OXYGENATION BY TIME-RESOLVED SPECTROSCOPY

  • Yamashita, Yutaka;Oda, Motoki;Ohmae, Etsuko;Tsuchiya, Yutaka
    • Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
    • /
    • 2001.06a
    • /
    • pp.2101-2101
    • /
    • 2001
  • Near-infrared spectroscopy is now being used in clinical diagnosis as a non-invasive monitor of tissue oxygenation state. However, due to lack of the optical pathlength information within tissues, it is still difficult to quantitate the hemoglobin concentration with present CW techniques. Time-resolved spectroscopy (TRS), which measures temporal profiles of emerging light from tissues, enables to estimate the pathlength distribution within tissues by converting time to distance. Consequently, quantitative measurement of tissue oxygenation is possible by analyzing the data with optical diffusion equation 1) or our Microscopic Beer-Lambert law2). Time-Resolved Spectroscopy System : TRS-1O3) Our TRS-10 system consists of a three-wavelength (759, 797, 833 nm) PLP as pulsed light source, a high speed PMT with high sensitivity and three signal-processing circuits for time-resolved measurement (CFD/TAC, A/D converter and histogram memory). Optical pulse train consisting of 759, 797 and 833nm is generated by PLP at 5㎒ repetition rate and irradiated a sample through a single optical fiber. The diffuse-reflected light from the sample is collected by a bundle fiber and then detected by the PMT for single photon measurement. After being amplified by a following fast amplifier, the electrical signals for each wavelength are picked out by CFD/TAC module. Then, a signal processing circuit integrated the TRS data for each wavelength individually. The simultaneous TRS measurement for three wavelengths achieved without any optical or mechanical switch. Experiment and Results Input and detection fibers of TRS-10 were attached at the human forehead with a fiber separation of 3cm. TRS measurements were continuously performed for about 20 minutes including 2 minutes hyper ventilation. It was observed that the total hemoglobin concentration was decreasing during the hyper ventilation and recovered until 2 minutes after hyper ventilation. On the other hand, the deoxy-hemoglobin concentration began to increase after hyper ventilation and had its peak at around 2 minute later, showing 502 drop from 75% to 60% due to inhibition of breathing by performing hyper ventilation. The results showed that this system might be able to quantitate the concentrations of oxy- and deoxy-hemoglobin in the human brain.

  • PDF

An Analysis of Voltage Characteristics for LC Resonant Frequency Band of Capacitor Compensation According to Moving of Electrical Separation Equipment of AF Track Circuit (AF궤도회로의 전기적 구분 장치 설치이전에 따른 커패시터 보상으로 LC공진 주파수 대역의 전압특성 분석)

  • Won, Seo-Yeon;Choi, Jae-Sik;Park, Hun-Jue;Kim, Hie-Sik
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.65 no.8
    • /
    • pp.1466-1477
    • /
    • 2016
  • This paper analyzes the electrical characteristic such as the impedance(Z), inductance(L), and cable resistance($R_p$) according to the change of cable length in order to move the electrical sorting device for distinguishing between AF non-insulated track circuits from the center of railway to outside railway. The simulation is performed to check the voltage difference between the voltage of sender and the voltage of receiver and determine the possibility of the voltage restoration availability in the frequency filter band through the capacitor compensation. It was applied to the results of the simulation to the sorting devices installed in the actual field. It is proved the availability by checking the measured voltage characteristic according to the capacitor compensating change of $10{\mu}F$ and $16{\mu}F$ before, and after the length of cable is increased with 6 meters. Through this, the prevention of breakdown and damage to facilities and the prevention the safety-related accidents of line workers from the train are expected according to moving the sorting devices of AR non-insulated track circuits to outside railway.

Management of Automated Vacuum Waste Collection Systems in Suburban Apartment Complexes (신도시 아파트단지의 생활폐기물 자동집하시설 운용 및 관리실태)

  • Oh, Jeongik;Lee, Hyunjeong
    • Journal of Korean Society of Environmental Engineers
    • /
    • v.38 no.2
    • /
    • pp.56-62
    • /
    • 2016
  • The purpose of this research is to explore both on-site manager's and resident's assessment of the Automated Vacuum Waste Collection System (AVWCS) in suburban apartment complexes. In doing so, a self-administered questionnaire survey was conducted in 10 districts and their 11 apartment complexes in the Seoul Metropolitan Area. The main findings can be summarized as follows: the managers considered the AVWCS to be economically efficient and environmentally fiendly, and suggested that the system be managed in a more professional way, with an advanced technology and by more qualified technicians. The recommendation was related to residents' complaints and frequent mechanical failures frequently occurring in waste inlets and waste transport piping of the system. For residents using the system, the system was satisfactory, and should be necessarily improved with more user-friendly features. Further, most comments made by the residents were relevant to waste inlets such as safety, cleanliness, prompt repair, odor reduction, waste separation. It's of significant to train residents with how to properly use the system, which is expected to substantially fall a number of residents' complaints. Therefore, both professional management of AVWCS and regular workshops on how to utilize it are crucial in order to heighten its strengths.

Export Prediction Using Separated Learning Method and Recommendation of Potential Export Countries (분리학습 모델을 이용한 수출액 예측 및 수출 유망국가 추천)

  • Jang, Yeongjin;Won, Jongkwan;Lee, Chaerok
    • Journal of Intelligence and Information Systems
    • /
    • v.28 no.1
    • /
    • pp.69-88
    • /
    • 2022
  • One of the characteristics of South Korea's economic structure is that it is highly dependent on exports. Thus, many businesses are closely related to the global economy and diplomatic situation. In addition, small and medium-sized enterprises(SMEs) specialized in exporting are struggling due to the spread of COVID-19. Therefore, this study aimed to develop a model to forecast exports for next year to support SMEs' export strategy and decision making. Also, this study proposed a strategy to recommend promising export countries of each item based on the forecasting model. We analyzed important variables used in previous studies such as country-specific, item-specific, and macro-economic variables and collected those variables to train our prediction model. Next, through the exploratory data analysis(EDA) it was found that exports, which is a target variable, have a highly skewed distribution. To deal with this issue and improve predictive performance, we suggest a separated learning method. In a separated learning method, the whole dataset is divided into homogeneous subgroups and a prediction algorithm is applied to each group. Thus, characteristics of each group can be more precisely trained using different input variables and algorithms. In this study, we divided the dataset into five subgroups based on the exports to decrease skewness of the target variable. After the separation, we found that each group has different characteristics in countries and goods. For example, In Group 1, most of the exporting countries are developing countries and the majority of exporting goods are low value products such as glass and prints. On the other hand, major exporting countries of South Korea such as China, USA, and Vietnam are included in Group 4 and Group 5 and most exporting goods in these groups are high value products. Then we used LightGBM(LGBM) and Exponential Moving Average(EMA) for prediction. Considering the characteristics of each group, models were built using LGBM for Group 1 to 4 and EMA for Group 5. To evaluate the performance of the model, we compare different model structures and algorithms. As a result, it was found that the separated learning model had best performance compared to other models. After the model was built, we also provided variable importance of each group using SHAP-value to add explainability of our model. Based on the prediction model, we proposed a second-stage recommendation strategy for potential export countries. In the first phase, BCG matrix was used to find Star and Question Mark markets that are expected to grow rapidly. In the second phase, we calculated scores for each country and recommendations were made according to ranking. Using this recommendation framework, potential export countries were selected and information about those countries for each item was presented. There are several implications of this study. First of all, most of the preceding studies have conducted research on the specific situation or country. However, this study use various variables and develops a machine learning model for a wide range of countries and items. Second, as to our knowledge, it is the first attempt to adopt a separated learning method for exports prediction. By separating the dataset into 5 homogeneous subgroups, we could enhance the predictive performance of the model. Also, more detailed explanation of models by group is provided using SHAP values. Lastly, this study has several practical implications. There are some platforms which serve trade information including KOTRA, but most of them are based on past data. Therefore, it is not easy for companies to predict future trends. By utilizing the model and recommendation strategy in this research, trade related services in each platform can be improved so that companies including SMEs can fully utilize the service when making strategies and decisions for exports.