• Journal of the Korea Society for Simulation
• /
• v.28 no.2
• /
• pp.89-95
• /
• 2019

This paper introduces the simulation concepts and technical approach of underwater weapon system performance analysis simulator, especially focused on probabilistic target detection concepts. We calculated the signal excess (SE) value using SONAR equation, then derived the probability density function(PDF) for target presence($H_1$) or absence($H_0$) cases, respectively. With the Neyman-Pearson detector criterion, we got the probability of detection($P_D$) while satisfying the given probability of false alarm($P_{FA}$). At every instance of simulation, target detection is decided in the probabilistic perspective. With the proposed detection implementation, we improved the model fidelity so that it could support the tactical decision during the operation.

• Journal of Korean Society on Water Environment
• /
• v.23 no.6
• /
• pp.951-960
• /
• 2007

Window interface to Hydrological Simulation Program-FORTRAN (WinHSPF) developed by the United States Environmental Protection Agency (EPA) was applied to the upstream of Nam-Han river watershed to examine its applicability for loading estimates in watershed scale and to evaluate non-point source control scenarios using BMPRAC in WinHSPF. The WinHSPF model was calibrated and verified for water flow using Ministry of Construction and Transportation (MOCT, 3 stations, 2003~2005) and water qualities using Ministry of Environment (MOE, 5 station, 2000~2006). Water flow and water quality simulation results were also satisfactory over the total simulation period. But outliers were occurred in the time series data of TN and TP at some regions and periods. Therefore, it required more profit calibration process for more various parameters. As a result, all the study was performed within the expectation considering the complexity of the watershed, pollutant sources and land uses intermixed in the watershed. The estimated pollutant load for annual average about $BOD_5$, T-N and T-P respectively. Nonpoint source loading had a great portion of total pollutant loading, about 86.5~95.2%. In WinHSPF, BMPRAC was applied to evaluate non-point source control scenarios (constructed wetland, wet detention ponds and infiltration basins). All the scenarios showed efficiency of non-point source removal. Overall, the HSPF model is adequate for simulating watersheds characteristics, and its application is recommended for watershed management and evaluation of best management practices.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.54 no.6
• /
• pp.111-119
• /
• 2012

Applicability of 8 day interval flow data for the calibration of hydrologic model was evaluated using Hydrological Simulation Program-Fortran (HSPF) at Kyungan watershed. The 8 day interval flow monitored by Ministry of Environment located at upstream was calibrated and periodically validated during 2004-2008. And continuous daily flow monitored by Ministry of Construction & Transportation (MOCT) and located at the mouth was compared with daily simulated data during 2004-2007 as spatial validation. Automatic calibration tool which is Model-Independent Parameter Estimation & Uncertainty Analysis (PEST) was applied for HSPF calibration procedure. The model efficiencies for calibration and periodic validation were 0.63 and 0.88, and model performances were fair and very good, respectively, based on criteria of calibration tolerances. Continuous daily stream flow at the mouth of Kyungan watershed were good agreement with observed continuous daily stream flow with showing 0.63 NS value. The PEST program is very useful tool for HSPF hydrologic calibration using non-continuous daily stream flow as well as continuous daily stream flow. The 8 day interval flow data monitored by MOE could be used to calibrate hydrologic model if the continuous daily stream flow is unavailable.

• Journal of Power Electronics
• /
• v.16 no.3
• /
• pp.1056-1066
• /
• 2016

Wireless power transfer (WPT) technology is now recognized as an efficient means of transferring power without physical contact. However, frequency detuning will greatly reduce the transmission power and efficiency of a WPT system. To overcome the difficulties associated with the traditional frequency-tracking methods, this paper proposes a Direct Phase Control (DPC) approach, based on the Second-Order Generalized Integrator Phase-Locked Loop (SOGI-PLL), to provide accurate frequency-tracking for WPT systems. The DPC determines the phase difference between the output voltage and current of the inverter in WPT systems, and the SOGI-PLL provides the phase of the resonant current for dynamically adjusting the output voltage frequency of the inverter. Further, the stability of this control method is analyzed using the linear system theory. The performance of the proposed frequency-tracking method is investigated under various operating conditions. Simulation and experimental results convincingly demonstrate that the proposed technique will track the quasi-resonant frequency automatically, and that the ZVS operation can be achieved.

• Current Optics and Photonics
• /
• v.6 no.6
• /
• pp.627-633
• /
• 2022

To realize uniform side pumping of solar lasers and improve their output power, a solar concentrating system based on off-axis parabolic mirrors is proposed. Four identical off-axis parabolic mirrors with focal length of 1,000 mm are toroidally arranged as the primary concentrator. Four two-dimensional compound parabolic concentrators (2D-CPCs) are designed as a secondary concentrator to further compress the focused spot induced by the parabolic mirrors, and the focused light is then homogenized by four rectangular diffusers and provides uniform pumping for a laser-crystal rod to achieve solar laser emission. Simulation results show that the solar power received by the laser rod, uniformity of the light spot, and output power of the solar laser are 7,872.7 W, 98%, and 351.8 W respectively. This uniform pumping configuration and concentrator design thus provide a new means for developing high-power side-pumped solid-state solar lasers.

• Journal of Korean Society of Transportation
• /
• v.22 no.1 s.72
• /
• pp.7-18
• /
• 2004

To solve the urban traffic congestion problem, Seoul and other major cities have operated the reversible lanes as Transportation Systems Manage-ment(TSM) method since 1981. However, few studies have been conducted to measure the effectiveness of reversible lane implementation and operation, and the reversible lanes have been implemented based on the experiential warrants rather than the study-based warrants. In this Paper the effect of reversible lanes operation has been analyzed by using the average delay and the fuel consumption. Four factors such as in and out flow of directional v/c, the ratio of directional volume, the number of reversible lanes and left-turn treatment(prohibition of LTs or protected LTs) were used to estimate the implementation effect of reversible lane operation by using TRANSYT-7F simulation package. In the case of six-lane urban arterial, the lower ratio of directional volume was found to warrant the reversible lanes when the simulation-based method was applied compared with the current experiential warrants.

• Journal of Korean Society of Transportation
• /
• v.27 no.1
• /
• pp.7-16
• /
• 2009

Korea Highway Capacity Manual (2001) proposes only LOS(Level of Service) analysis method on non-control and two-way-stop intersections, not dealing with the analysis method on LOS for roundabouts, nor even including the term 'roundabout'. This study selects proper MOEs for roundabouts and criteria the LOS through simulation analysis. To attain this goal, the authors reviewed the methods to select proper MOEs in the first step, criteria the Los. For this study, the MOEs were chosen from existing literature, and used for the criteria. The MOEs to be applied to roundabouts in this research were entry traffic volume, v/c (volume/capacity) ratio, and average vehicle delays. The results showed that the maximum entry traffic volume(LOS F) at local one-lane roundabout was analyzed to be 1,700pcph and average vehicle delay 18 seconds LOS A was analyzed as 700pcph and average vehicle delay 3 seconds and v/c 0.41 in this case Maximum entry traffic volume(LOS F) at local area 2 lane roundabouts was analyzed as 2,900pcph and their average vehicle delay as 31 seconds LOS A was analyzed to be 1.500pcph and average vehicle delay 8 seconds, v/c 0.52.

• Journal of Korean Society of Transportation
• /
• v.32 no.2
• /
• pp.106-118
• /
• 2014

The objective of this study is to develop a methodology for evaluating the effectiveness of in-vehicle pedestrian warning systems. Driving Simulator-based experiments were conducted to collect data to represent driver's responsive behavior. The braking frequency, lane change duration, and collision speed were used as measure of effectiveness (MOE) to evaluate the effectiveness. Collision speed data obtained from the simulation experiments were further used to predict pedestrian injury severity. Results demonstrated the effectiveness of warning information systems by reducing the pedestrian injury severity. It is expected that the proposed evaluation methodology and outcomes will be useful in developing various vehicular technologies and relevant policies to enhance pedestrian safety.

• Journal of Korean Society on Water Environment
• /
• v.26 no.1
• /
• pp.168-176
• /
• 2010

This study proposes the improvement of the present Total Maximum Daily Load (TMDL) management system of MOE (Ministry of Environment). The margin of safety (MOS) is calculated by a method using standard error and a method using variability and uncertainty. The allocation of pollutant loads are calculated using three methods, equal load reduction method, equal percent removal method and method using equity standards. This study applied the improved TMDL management system to the Anyangcheon watershed. Since MOS varies from 12% to 44% due to the high variability of measured and simulated data, it must not be ignored in the TMDL. The method using equity standards is the most proper in this application since the others produced unrealistic allocations. Area, runoff, water use quantity, population and budget are considered for equity standards. This study shows that this allocation method can be also applicable for the administrative units as well as the sub-watersheds. Finally, Hydrologic Simulation Program-FORTRAN (HSPF) with the allocated pollutant load was used to confirm whether it satisfy the water quality standard or not. This study will be helpful to improve the MOS and allocation system TMDL in the future.

• Journal of Korean Society of Transportation
• /
• v.36 no.2
• /
• pp.67-85
• /
• 2018

Vehicle platooning through wireless communication and automated driving technology has become realized. Platooning is a technique in which several vehicles travel at regular intervals while maintaining a minimum safety distance. Truck platooning is of keen interest because it contributes to preventing truck crashes and reducing vehicle emissions, in addition to the increase in truck flow capacity. However, it should be noted that interactions between vehicle platoons and adjacent manually-driven vehicles (MV) significantly give an impact on the performance of traffic flow. In particular, when vehicles entering from on-ramp attempt to merge into the mainstream of freeway, proper interactions by adjusting platoon size and inter-platoon spacing are required to maximize traffic performance. This study developed a methodology for establishing operational strategies for truck platoonings on freeway on-ramp areas. Average speed and conflict rate were used as measure of effectiveness (MOE) to evaluate operational efficiency and safety. Microscopic traffic simulation experiments using VISSIM were conducted to evaluate the effectiveness of various platooning scenarios. A decision making process for selecting better platoon operations to satisfy operations and safety requirements was proposed. It was revealed that a platoon operating scenario with 50m inter-platoon spacing and the platoon consisting of 6 vehicles outperformed other scenarios. The proposed methodology would effectively support the realization of novel traffic management concepts in the era of automated driving environments.