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Gasoline direct injection (GDI) engines emit less carbon dioxide (CO2) than port fuel injection (PFI) engines when fossil fuel conditions are the same. However, GDI engines emit more ultrafine particulate matter, which can have negative health effects, leading to particulate emission regulations. To satisfy these regulations, various studies have been done to reduce particulate matter, and several studies focused on lubricants. This study focuses on the influence of lubricant on the formation of particulate matter and its effect on particulate emissions in GDI engines. An instrumented, combustion and optical singe-cylinder GDI engine fueled by four different lubricant-gasoline blends was used with various injection conditions. Combustion experiments were used to determine combustion characteristics, and gaseous emissions indicated that the lubricant did not influence mixture homogeneity but had an impact on unburned fuels. Optical experiments showed that the lubricant did not influence spray but did influence wall film formation during the injection period, which is a major factor affecting particulate matter generation. Particulate emissions indicated that lubricant included in the wall film significantly affected PN emissions depending on injection conditions. Additionally, the wall film influenced by the lubricant affected the overall particle size and its distribution.

To comply with reinforced emission regulations for harmful exhaust gases, including carbon dioxide (CO2) emitted as a greenhouse gas, improved technologies for reducing CO2 and fuel consumption are being developed. Stable lean combustion, which has the advantage of improved fuel economy and reduced emission levels, can be achieved using a sprayguided-type direct-injection (DI) combustion system. The system comprises a centrally mounted injector and closely positioned spark plugs, which ensure the combustion reliability of a stratified mixture under ultra-lean conditions. The aim of this study is to investigate the combustion and emission characteristics of a lean-burn gasoline DI engine. At an excess air ratio of 4.0, approximately 23% improvement in fuel economy was achieved through optimal event timing, which was delayed for injection and advanced for ignition, compared to that under stoichiometric conditions, while NOx and HC emissions increased. The combustion characteristics of a stratified mixture in a spray-guided-type DI system were similar to those in DI diesel engines, resulting in smoke generation and difficulty in three-way catalystutilization. Although a different operating strategy might decrease fuel consumption, it will not be helpful in reducing NOx and smoke emissions; therefore, alternatives should be pursued to achieve compliance with emission regulations.

This paper analyzes what is mitigated as spoofing attack using the U-Blox Receiver and GPS RF signal generator developed at ETRI. Generally the spoofing attack made the target receiver to be wrong navigation solution by providing false measurement of code and carrier. So we analyzed the impact of spoofing attack through the signal strength and navigation solution. In oder to test of effect of anti-spoofing signal, we consider the signal with antiphase code to spoofing signal and generated GPS normal signal and spoofing signal and anti-spoofing signal using GPS RF signal generator. This paper analyzed that the GPS receiver was responded to the spoofing attack according to code phase difference between spoofing and anti-spoofing signal. We confirmed that the spoofing signal was disappeared by anti-spoofing signal if code phase is an exact match.

Minimum-time attitude maneuvers of three-axis stabilized spacecraft are presented to study the feasibility of using three magnetic torquers perform large angle maneuvers. Previous applications of magnetic torquers have been limited to spin-stabilized satellites or supplemental actuators of three-axis stabilized satellites because of the capability of magnetic torquers to produce torques about a specific axes. The minimum-time attitude maneuver problem is solved by applying a parameter optimization method for orbital cases to verify that the magnetic torque system can perform as required Direct collocation and a nonlinear programming method with a constraining method by Simpson's rule are used to convert the minimum-time maneuver problems into parameter optimization problems. An appropriate number of nodes is presented to find a bang-bang type solution to the minimum-time problem. Some modifications in the boundary conditions of final attitude are made to solve the problem more robustly and efficiently. The numerical studies illustrate that the presented method can provide a capable and robust attitude reorientation by using only magnetic torquers. However, the required maneuver times are relatively longer than when thrusters or wheels are used Performance of the system in the presence of errors in the magnetometer as well as the geomagnetic field model still good.

In this paper, we propose a novel L5 tracking scheme for QZSS satellite using L1/L5 synchronization characteristics in the L1/L5 receiver. The QZSS consists of a multiple number of satellites that fly in the orbit passing through the near zenith over Japan. The Michibiki, the first QZSS satellite, is transmitting all the positioning signals including the L1/L5 signals. As the code length of L5 signal is 10- times that of L1 signal, the L5 acquisition process takes too much time. To reduce this acquisition processing time, a higher number of correlators should be used in the acquisition module. These makes the hardware complexity and the computation power increase. As the proposed scheme uses the L1 tracking results such as the PRN, bit synchronization, and Doppler frequency, it doesn't need the extra L5 acquisition module and provides fast and stable tracking of L5 signal. The feasibility of the proposed scheme is demonstrated by processing L1/L5 signal transmitted from the QZSS satellite.

In this study, numerical simulation of airframes separating from a missile system has been preformed. For the time-accurate trajectory simulation, six D.O.F equations of motion of multiply connected bodies were derived and these equations have been coupled with the unstructured overset mesh technique for the treatment of independent mesh blocks moving with each body component. Applications were made for the simulation of the airframe separation at missile angles of attack of 0 and 5 degrees. It was demonstrated that the present method is efficient and robust for the prediction of unsteady time-accurate flow fields involving multiple bodies in relative motion.

GPS is widely used in the location based service and the telematics service. And communication systems, electrical power grids, and financial networks also rely on GPS for synchronization and operational efficiency. GPS applications are newly being developed and becomes very critical infrastructure. However, GPS couldn’t be used by intentional interference signal of even low power, low cost transmitters. In order to prevent the damage caused by illegal interference signal to GPS, GPS interference monitoring system(IMS) should be developed and operated. So, this paper presents the development and the test results of the GPS IMS which provides the detection, the direction finding and the location of GPS interference signal. The main functions are verified by test results of the interference test-bed environment.

In this paper, we present design features, implementation, and validation of a satellite simulator subsystem for the Korea Multi-Purpose Satellite-2 (KOMPSAT-2). The satellite simulator subsystem is implemented on a personal computer to minimize costs and trouble on embedding onboard flight software into the simulator. An object-oriented design methodology is employed to maximize software reusability. Also, instead of a high-cost commercial database, XML is used for the manipulation of spacecraft characteristics data, telecommand, telemetry, and simulation data. The KOMPSAT-2 satellite simulator subsystem is validated by various simulations for autonomous onboard launch and early orbit phase operations, anomaly operation, and science fine mode operation. It is also officially verified by successfully passing various tests such as the satellite simulator subsystem test, mission control element system integration test, interface test, site installation test, and acceptance test.

In this paper, we introduce the type of spoofing signal and the method of spoofing mitigation. The spoofing has three type: simplistic, intermediate, sophisticated and we will be interested in the intermediate spoofing. The intermediate spoofers synchronize its counterfeit GNSS signals with the current broadcast GNSS signals. So, if the receiver is attacked by a spoofer, it should be able to detect the spoofing signal through the absolute and relative GNSS signal strength, signal strength changing rate, Bound and compare range rates, etc. There are two way to mitigate spoofing signal, elimination of spoofing channel through the signal processing and counterbalance of spoofing signal through the RF phase control. For simulation, we generated the intermediate spoofing signal using the software GNSS signal generator simulator(SGGS), the intermediate spoofers synchronize its counterfeit GPS signals with the current broadcast GPS signals and generated the anti-spoofing signal to mitigate the spoofing signal. The software GPS receiver simulator(SGRS) received the mixed signal the spoofing, anti-spoofing and normal signal from SGGS, and process the signals. In paper, we can check that the DLL and PLL tracking loop error are generated and pseudo-range is changed linear according to mitigate to spoofing signal when the anti-spoofing signal is entered. As a result, we can check that navigation solution is changed from abnormal by spoofing signal to normal by anti-spoofing signal.

A multi-mission GEO satellite, COMS has three payloads including Ka-band communications, GOCI, and MI. COMS SGCS is the only system for monitor and control of the satellite in orbit. In order to fulfill the mission operations of the three payloads and spacecraft bus, COMS SGCS performs the following functions such as reception and processing of telemetry data via S-band link, planning and transmission of telecommand, tracking and ranging of the satellite, control and monitoring of SGCS equipment, analysis and simulation of the satellite, processing and analysis of flight dynamics data, and mission scheduling and reporting. By the proper functional allocations, COMS SGCS is divided into five subsystems such as TTC, ROS, MPS, FDS, and CSS. COMS SGCS is linked with MSC, KOSC, and IDACS for satellite related data exchange. The software in the COMS SGCS is designed using the object-oriented methodology and implemented using Microsoft C# .NET environment on Intel microprocessor based computers. The hardware in the COMS SGCS includes 13-m S-band mono-pulse Cassegrain antenna and RF/BB equipment. In this paper, development of the COMS SGCS is described with respect to system functional allocations, software and hardware design, system implementation, and system test.

This paper presents the PC based experimental software receiver which has been recently extended to a high bandwidth multiple frequency LI signal for GPS and El signal software receiver. The presentation briefly touches upon on signal tracking using prototyping hardware antenna, RF-IF section and software baseband section. In this paper, the efficient algorithms are developed about the signal acquisition and tracking parts in order to obtain the accuracy pseudorange. Finally, the pseudorange is calculated through the relative channel delay received through the different satellite of LI frequency band.

Modernized GPS and Galileo system will be available to civil users, thus there is a need for unified platform that can receive multi-frequency signals of Galileo/GPS to develop and test a variety of applications. ETRI involved in developing technologies of GNSS ground infrastructure and next generation search and rescue beacon from 2007 up to 2010. We are going to develop high performance S/W receiver for feasibility study on developing a receiver for GNSS ground sensor station for the program. In order to test and verify S/W receiver prototype digitized IF signal generator is developed. The experimental result for the S/W receiver is presented in future.

Satellite system has lots of fault causes. For some communications satellite systems, fault management and data preservation are required to exchange data continuously and provide broadcasting service. In this paper, we have proposed fault management of satellite system using penalty method, data buffer and recovery manager. The penalty manager imposes penalty according to fault degree and manages fault quantitatively. Data Buffer has the function to store data in fault situation and prevent data damage. Recovery manager performs system monitoring and to operates recovery process in fault situation. Proposed method is fundamental concept of the architectural characteristics and enhances satellite fault management performance. This capability permits the satellite to detect and correct some of its own failures autonomously. Also, the effect of penalty method and data buffer on fault management design has been discussed.

In this paper, we present design and implementation features and validation of KOMPSAT-2 simulator (SIM). The SIM is implemented on PC server to minimize costs and troubles on embedding onboard flight software into simulator. Object oriented design methodology is employed to maximized S/W reusability, and XML is used for S/C characteristics data, TC, TM and Simulation data instead of expensive commercial DB. Consequently, we can reduce costs for the system development, efforts on embedding flight software. A simulation for science fine mode operation is presented to demonstrate the overall validation of SIM. SIM has been verified officially by various tests such as SIM subsystem test, MCE system integration test, interface test, site installation test, and acceptance test. They were performed successfully.

The simulation of LEOP operations was presented. A generic software satellite simulator was used for the analysis and verification of LEOP operations. A specific spacecraft model was implemented in the simulator for the LEOP operation scenario. The satellite model includes spacecraft subsystems and the flight dynamics models. LEOP simulation was performed by the stored relative time command set in the on-board flight software that was implemented on the simulator. The simulation started from the separation of a launch vehicle and executed solar array deployment, deployment test, and activation of sun point mode. Simulation results of earth searching operation and orbit adjusts maneuver are also provided.