• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.176-184
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• 2010

The power simulator for a LEO satellite is a useful tool to analyze mission validity and energy balance for various mission scenarios by estimating power generation, power consumption, depth of discharge, bus voltage, charging/discharging current, etc. In this paper, it is described the calculation algorithm of the solar array (SA) power, the satellite load power and the battery modeling method to develop a satellite power simulation. To simulate the SA power generation, three different operation modes (DET, MPPT, CV) of SAR (Solar Array Regulator) are considered with a SA model. The satellite load power is estimated using the satellite unit power database, the unit on/off configuration at some satellite operation modes. The bus voltage and battery charging/discharging current at the specific DoD (Depth of Discharge) are calculated based on the battery characteristics. By this satellite power simulator, it can be conveniently analyzed the energy balance and the validity of a planned mission of a LEO satellite.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.3
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• pp.116-130
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• 2023

Expressways play pivotal roles in cargo transportation because of their superior accessibility and mobility compared to rail and air. On the other hand, there is a limit to the accurate calculation of cargo transportation performance using existing highways owing to the mixture of vehicle types and difficulty in identifying cargo loads of individual cargo vehicles. This paper presents an algorithm for calculating more reliable cargo transportation performance using big data. The traffic performance (veh·km/day) was derived using the data collected from Toll Collecting System. The average tolerance weight for each vehicle type and the cargo load unit (ton/unit) considering it was calculated using vehicle specification information data and high-speed and low-speed axis data. This study calculated the cargo transportation performance by section and type using various online integrated highway data and presented a method for calculating the transportation performance by linking open business offices and private highways.

• Journal of Korean Port Research
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• v.14 no.3
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• pp.313-319
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• 2000

In this paper, we proposed the model of wireless communication for ACTS using DSRC and the DSRC system for T/C. The proposed wireless communication model is how to join with DSRC and other wireless communication in port. The DSRC system for T/C is the first application to the unit of port Facilities Automation on stacking area. The DSRC system is communicated between OBE and RSE using 5.8Hz ISM band frequency. The previous works of DSRC applications are gate automation. In these cases, the road trackers are difficult to obtain information of the port in the stacking area. So we used the DSRC for the wireless communication for the port Facilities Automation. Using DSRC, the load trackers obtain more information in the port and contacts to ITS on back-roads of port. The proposed communication system is serviced to reelection of port statistics.

• Journal of information and communication convergence engineering
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• v.8 no.5
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• pp.534-538
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• 2010

Efficient control of a marine engine requires an engine control unit (ECU) system that handles fast and precise signal processes for in-coming and out-going signals from fast running engines. In order to handle these roles, the sequential control has been adapted in the ECU system in small and medium size ship engines, which has caused high production cost and complexity of the system. Hence, this paper is focused on developing an distributed ECU system for high speed and high precision control of a marine engine by efficiently combining a CPLD chip and a microprocessor. By sharing load at the MCU with the designed CPLD chip, we could achieve in driving a marine engine with high speed and precise control so that the ECU board has been simplified and its production cost has been reduced.

• Journal of the Korea Society for Simulation
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• v.13 no.1
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• pp.25-39
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• 2004

Simulation has been recognized as one of major application areas of world wide web. Over the last several years, most research has been focused on the development of web-based simulation languages mostly using JAVA and validation of simulation modeling on web with the newly developed languages. In this paper, we develop a tentative web-based simulator for a simple unit-load automated warehouse system, named Web-SAW. In constructing Web-SAW, we program a user interface program, a simulation logic program, and an animation program with JAVA while utilizing the class library functions and embodiment environment of existing web-based simulation languages. Web-SAW simulates the automated warehouse system with the user input about system operation, displays the animation on a static background representing the system, and generates the various textual outputs after simulation.

• Journal of Digital Convergence
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• v.17 no.7
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• pp.59-71
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• 2019

The distribution logistics center has its own inventory, so designing an efficient storage area is very important. The purpose of this study is to present the optimal storage area calculation method for distribution logistics center considering the use of standard pallet unit load, and the results of this study are as follows. First, standard rack modules for storing T-11 and T-12 type pallet, which is generally used in Korea, were defined. Second, a variety of pallet transport equipments were investigated and analyzed to define the standard transport equipment's work passageway by type. Finally, it has great implications in terms of suggesting measures to minimize unused space that may occur during placement of pallet rack modules within storage space, as well as the easy and optimal calculation of the storage area for the distribution logistics center. Future research require a study on the layout of the entire distribution logistics center, which reflects the latest logistics technologies, such as standard rack modules for Mini-Load and GTP picking system.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1034-1041
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• 2011

Generally, In distributed online game server system, game maps are processed separately by means of dividing into several unit blocks. But the keeping normal distribution of user in game map is very difficult because preferences of game users are not same according to individual user's private character. For this reason, if the huge number of users concentrate on particular region of same game map at once, the game server exceed their threshold so that the system can be getting down. Conversely, the efficiency of system goes down considerably because the game server must perform map processing continuously even under user_empty situation. To solve this problem, in this paper, we propose a Map management method to control relatively normal distribution of users in game maps using Map Balance Server. In suggested model, we can reduce the load of game servers by means of turn off the game map processing temporary when a server is under user_empty situation. we also can maximize server performance by means of redistribution of map processing load among servers.

• Journal of Electrical Engineering and Technology
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• v.3 no.3
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• pp.354-362
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• 2008

In this paper, a new algorithm of optimal voltage control is proposed for the Distribution Automation System (DAS) based on constants of four terminal network modeling. In the proposed method, the voltage profiles along feeders are estimated from the measurement of the current and power factor by a Feeder Remote Terminal Unit (FRTU) installed at each node. Whenever the voltage profile violates the restriction, the voltage control strategy is applied to keep the voltage levels along the feeders within the pre-specified range through the modification and coordination of the transformer under-load tap changers (ULTC), step voltage regulator (SVR), as well as shunt condenser. In the case studies, the estimation and control of the voltages have been testified in a radial distribution system with 11 nodes.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.5
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• pp.272-281
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• 1988

The problem of optimal transmission system planning is to find the most economical locations and time of transmission line construction under the various constraints such as available rights-of-way, finances, the technical characteristics of power system, and the reliability criterion of power supply, and so on. In this paper the constraint of right-of-way is represented as a finite set of available rights-of-way. And the constructed for a unit period. The electrical constraints are represented in terms of line overload and steady state stability margin. And the reliability criterion is dealt with the suppression of failure cost and with single-contingency analysis. In general, the transmission planning problem requires integer solutions and its objective function is nonlinear. In this paper the objective function is defined as a sum of the present values of construction cost and the minimum operating cost of power system. The latter is represented as a sum of generation cost and failure cost considering the change of yearly load, economic dispatch, and the line contingency. For the calculation of operating cost linear programming is adopted on the base of DC load flow calculation, and for the optimization of main objective function nonlinear Branch-and-Bound algorithm is used. Finally, for improving the efficiency of B & B algorithm a new sensitivity analysis algorithm is proposed.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.113-117
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• 2004

Such social structures as bridges, buildings, dams and towers have been transformed by their own load or fundamental ground. They have been behaved by other external causes. These regular or irregular behaviors threaten to do their users safety. Therefore, to monitor the load of the structures or reaction shown by them could help to verify their behaviors. RTK GPS allows the use of a static base station and remote rover unit to allow for data collection within several seconds and in real time. It is useful for monitoring the behaviors of massive structures like bridges. In this Study, Among GPS methods, we used RTK GPS to analyze the precision of monitoring and then on the basis of it, we developed a monitoring system using RTK GPS when measured the behavior of main tower of a suspension bridge by using RTK GPS. Comparing a deviation between observation values, X axis was 1mm, Y axis was 1mm and Z axis 2.2mm. It turned out that it was possible to monitor and measure structures by RTK GPS.