• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.5
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• pp.877-884
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• 2017

A method of common earth, which is proposed by French Railway(SNCF) and is applied to high speed railway, minimizes the effect of the traction return current from tracks so that trackside electric devices can be protected and operation and maintenance staffs are kept out from injury in an electric railway environment. According to it, all the new domestic electric railway lines are replaced from existing individual earth method to the common earth method. In this paper, we analyze the correlation between common earth method and traction return current to prove whether the common earth has surely contributed to minimize the effect of the traction return current. The analysis was done based on the measurement of the traction return current at the domestic high speed railway line.

• Structural Engineering and Mechanics
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• v.68 no.4
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• pp.459-473
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• 2018

Temperature fields and temperature deformations induced by time-varying solar radiation, shadow, and heat exchange are of great importance for the ride safety and quality of the maglev system. Accurate evaluations of their effects on the dynamic performances are necessary to avoid unexpected loss of service performance. This paper presents a numerical approach to determine temperature effects on the maglev train/guideway interaction system. Heat flux density and heat transfer coefficient of different components of a 25 m simply supported concrete guideway on Shanghai High-speed Maglev Commercial Operation Line is calculated, and an appropriate section mesh is used to consider the time-varying shadow on guideway surfaces. Based on the heat-stress coupled technology, temperature distributions and deformation fields of the guideway are then computed via Finite Element method. Combining guideway irregularities and thermal deformations as the external excitations, a numerical maglev train/guideway interaction model is proposed to analyze the temperature effect. The responses comparison including and excluding temperature effect indicates that the temperature deformation plays an important role in amplifying the response of a running maglev, and the parameter analysis results suggest that climatic and environmental factors significantly affect the temperature effects on the coupled maglev system.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.6
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• pp.602-609
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• 2003

Emerging high-speed next-generation Internet is enabling immersive media communication systems and applications to realize geographically distributed team collaborations while overcoming the limit of distance and time. Focusing on the reliable real-time delivery of 3D (i.e., stereo) video among corresponding parties, in this paper, key schemes for stereo video processing/display and reliable transport of stereo video packets over high-speed Internet are designed and implemented. The performance of proposed stereo video delivery system is evaluated both by emulating various network situations for quantitative comparison and by transmitting over real-world Internet up to the speed of around 100 Mbps. The results demonstrate the feasibility of the proposed system in supporting the desired immersive communication.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.1
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• pp.103-110
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• 2013

WAVE system is a vehicle communication technology. The system provides the services to prevent vehicle accidents that might occur during driving. Also, it is used to provide various services such as monitoring vehicle management and system failure. In this paper, we divide module that manages WAVE MAC state into a WSMP base MLME module and IP base module and we design and implement a parameter environment between WME module to manage the state of the WAVE system and MLMEX module to mange IP base of WAVE MAC therefore the date to be processed.Also, in order to verify the validity, we have carried out experiments to compare the speed of data processing by dividing data of 5Mbyte, 10Mbyte, 20Mbyte into the packets of 2KByte and 4KByte. Therefore, in WAVE system, the Parameter environments and data processing speed between WME and MLMEX module can be utilized in the various service of vehicle communication technology depending on the speed of data processing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1A
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• pp.16-24
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• 2010

High Speed Uplink Packet Access(HSUPA) is a WCDMA Release 6 technology which corresponds to High Speed Downlink Packet Access(HSDPA). Node B Supports fast scheduling, Hybrid ARQ(HARQ), short Transmission Time Interval(TTI) for high rate uplink packet data. It is very important to detect Iub congestion to improve end user's Quality of Service(QoS). This paper proposes Node B Congestion Detection(BCD) mechanism and suggests to use the hybrid of Transport Network Layer(TNL) congestion detection and BCD. It is shown that HSUPA user throughput performance can be improved by the proposed method even with small Iub bandwidth.

• Journal of Information Processing Systems
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• v.18 no.3
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• pp.428-442
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• 2022

A reliable automatic passenger counting (APC) system is a key point in transportation related to the efficient scheduling and management of transport routes. In this study, we introduce a lightweight head detection network using deep learning applicable to an embedded system. Currently, object detection algorithms using deep learning have been found to be successful. However, these algorithms essentially need a graphics processing unit (GPU) to make them performable in real-time. So, we modify a Tiny-YOLOv3 network using certain techniques to speed up the proposed network and to make it more accurate in a non-GPU environment. Finally, we introduce an APC system, which is performable in real-time on embedded systems, using the proposed head detection algorithm. We implement and test the proposed APC system on a Samsung ARTIK 710 board. The experimental results on three public head datasets reflect the detection accuracy and efficiency of the proposed head detection network against Tiny-YOLOv3. Moreover, to test the proposed APC system, we measured the accuracy and recognition speed by repeating 50 instances of entering and 50 instances of exiting. These experimental results showed 99% accuracy and a 0.041-second recognition speed despite the fact that only the CPU was used.

• Membrane and Water Treatment
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• v.13 no.5
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• pp.219-225
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• 2022

5th Assessment Report of the Intergovernmental Panel on Climate Change Weather (AR5) predicts that recent severe hydrological events will affect the quality of water and increase water pollution. To analyze changes in water quality due to future climate change, input data (precipitation, average temperature, relative humidity, average wind speed, and solar radiation) were compiled into a representative concentration curve (RC), defined using 8.5. AR5 and future use are calculated based on land use. Semi-distributed emission model Calculate emissions for each target period. Meteorological factors affecting water quality (precipitation, temperature, and flow) were input into a multiple linear regression (MLR) model and an artificial neural network (ANN) to analyze the data. Extensive experimental studies of flow properties have been carried out. In addition, an Acoustic Doppler Velocity (ADV) device was used to monitor the flow of a large open channel connection in a wastewater treatment plant in Ho Chi Minh City. Observations were made along different streams at different locations and at different depths. Analysis of measurement data shows average speed profile, aspect ratio, vertical position Measure, and ratio the vertical to bottom distance for maximum speed and water depth. This result indicates that the transport effect of the compound was considered when preparing the hazard analysis.

• New & Renewable Energy
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• v.20 no.2
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• pp.35-43
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• 2024

A pump turbine is a technically matured option for energy production and storage systems. At the off-design operating range, the pump turbine succumbed to flow instabilities, which correlated with the pump turbine geometry. A low specific speed pump turbine was designed and modified according to the impeller blade angle. Reynolds-Average Navier-Stokes is carried out with a shear stress transport turbulence model to evaluate the detailed flow characteristics in the pump turbine. The impeller blade inlet angle (𝛽₁) and outlet angle (𝛽₂) are used to evaluate hydraulic loss in the pump turbine. When 𝛽₁ changed from low to high value, the maximum efficiency is increased by 4.75% in turbine mode. The S-Curve inclination is reduced by 8% and 42% for changes in 𝛽₁ and 𝛽₂ from low to high values, respectively. At α = 21°, the shock loss coefficient (𝜁_s) is reduced by 16% and 19% with increases of 𝛽₁ and 𝛽₂ from low to high values, respectively. When 𝛽₁ and 𝛽₂ values increased from low to high, the impeller friction coefficient (𝜁_f) increased and decreased by 20% and 8%, respectively. Hence, the high 𝛽₂ effectively reduced the loss coefficient and S-Curve inclination.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.3 no.2 s.5
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• pp.29-40
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• 2004

The performance of the National Highway is raised, but the capacity of the signalized intersection on the National Highway is low. It's operated by TOD(Time Of Day) mode. To evaluate of the performance of COSMOS(Cycle, Offset, Split Model for Seoul), a real time traffic adaptive signal control system, on the National Highway, studied volume, travel time and queuing length at TOD control and TRC(Traffic responsive Control). Consequently, the average travel speed at TRC is high $2.9\~16.7$km/h then the average travel speed at TOD control. And te queuing length at TRC is low $15\~196m$ then the queuing length at TOD control.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.3
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• pp.52-59
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• 2016

COSMOS system which was developed in Seoul for real-time signal control was designed to judge traffic condition for practicing signal operation. However, it occurs efficiency problem that stop line detection and queue length detection could not judge overflow saturation of street. For that reason, following research process GPS data of Seoul city's corporationowned taxi to calculate travel speed that excluded existing system of stop line detection and queue length detection. Also, "Research of calculating queue length by GPS data" which was progressed with following research expressed queue length. It is based on establishing algorithm of judging congestion situation. The algorithm was applied to a few areas where appeared congestion situation consistently to confirm real time traffic condition with established network. [Entrance of the National Sport Institute ${\rightarrow}$ Gangnam station Intersection, Yuksam station intersection ${\rightarrow}$ National Sport Institute.