• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.1108-1110
• /
• 2003

MSC(Multi-Spectral Camera) which is a unique payload for KOMPSAT-2, comprises main three subsystems of PMU(Paylaod Management Unit), EOS(Electro -Optical Subsystem) and PDTS(Payload Data Transmission Subsystem). The PMU, as a main controller of MSC, performs major tasks such as interfacing with S/C(Space Craft), controlling the MSC operation, distributing and controlling of operating power to all MSC including thermal unit, etc. In this paper the H/W configurations as well as the functions of PMU are introduced and possible changes for the future development are suggested.

• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.637-640
• /
• 2005

In the development of a electronic system for a optical payload comprising mainly EOS(Electro-Optical Sub-system) and PDTS(Payload Data Transmission Sub-system), many aspects should be investigated and discussed for the easy implementation, for th e higher reliability of operation and for the effective ness in cost, size and weight as well as for the secure interface with components of a satellite bus, etc. As important aspects the interfaces between a satellite bus and a payload, and some design features of the CEU(Camera Electronics Unit) inside the payload are described in this paper. Interfaces between a satellite bus and a payload depend considerably on whether t he payload carries the PMU(Payload Management Un it), which functions as main controller of the Payload, or not. With the PMU inside the payload, EOS and PDTS control is performed through the PMU keep ing the least interfaces of control signals and primary power lines, while the EOS and PDTS control is performed directly by the satellite bus components using relatively many control signals when no PMU exists inside the payload. For the CEU design the output channel configurations of panchromatic and multi-spectral bands including the video image data inter face between EOS and PDTS are described conceptually. The timing information control which is also important and necessary to interpret the received image data is described.

• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.478-481
• /
• 2005

The PMU (Payload Management Unit) is the main subsystem for the management, control and power supply of the MSC (Multi-Spectral Camera) Payload operation. It is the most important function for the electro-optical camera system that performs the Non-Uniformity Correction (NUC) function of the raw imagery data, rearranges the data from the CCD (Charge Coupled Device) detector and output it to the Data Compression and Storage Unit (DCSU). The NUC board in PMU performs it. In this paper, the NUC board system is described in terms of the configuration and the function, the efficiency for non-uniformity correction, and the influence of the data compression upon the peculiar feature of the CCD pixel. The NUC board is an image-processing unit within the PMU that receives video data from the CEV (Camera Electronic Unit) boards via a hotlinkand performs non-uniformity corrections upon the pixels according to commands received from the SBC (Single Board Computer) in the PMU. The lossy compression in DCSU needs the NUC in on-orbit condition.

• Journal of Electrical Engineering and Technology
• /
• v.7 no.5
• /
• pp.653-658
• /
• 2012

Load modeling has a significant influence on power system analysis and control. In recent years, measurement-based load modeling has been widely practiced. In the load modeling algorithm, the model structure is determined and the parameters of the established model are estimated. For parameter estimation, least-squares optimization method is applied. The model parameters are estimated so that the error between the measured values and the predicted values is to be minimized. By introducing sliding window concept, on-line load modeling method can be performed which reflects the dynamic behaviors of loads in real-time. For the purpose of data acquisition, the measurement system including PMU is implemented in university level. In this paper, case studies are performed using real PMU data from Korea Univ. and Seoul National University of Science and Technology. The performances of modeling real and reactive power behaviors using exponential and ZIP load model are evaluated.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.3 no.3
• /
• pp.158-166
• /
• 2008

These days, mobile embedded systems adopt flash memory capable of XIP feature since they can reduce memory usage, power consumption, and software load time. XIP provides direct access to ROM and flash memory for processors. However, using XIP incurs unnecessary degradation of applications' performance because direct access to ROM and flash memory shows more delay than that to main memory. In this paper, we propose a memory management framework, dynamic XIP, which can resolve the performance degradation of using XIP. Using a constrained RAM cache, dynamic XIP can dynamically change XIP region according to page access pattern to reduce performance degradation in execution time or energy consumption resulting from native XIP problem. The proposed framework consists of a page profiler gathering applications' memory access pattern using PMU and an XIP manager deciding that a page is accessed whether in main memory or in flash memory. The proposed framework is implemented and evaluated in Linux kernel. Our evaluation shows that our framework can reduce execution time at most 25% and energy consumption at most 22% compared with using XIP-only case adopted in general mobile embedded systems. Moreover, the evaluation shows that in execution time and energy consumption, our modified LRU algorithm with code page filters can reduce more than at most 90% and 80% respectively compared with applying just existing LRU algorithm to dynamic XIP.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.4
• /
• pp.303-310
• /
• 2020

This paper describes a Power Monitoring Unit (PMU) for Unmanned Aerial Vehicle (UAV) electrical system, It is designed for the PMU which performs data sensing of generator, transformer rectifier unit (TRU), battery and gear box installed in UAV and operate power ON/OFF devices of mission equipment. The PMU measures the voltage and current for the aircraft power source (generators, transformer rectifier unit and battery), measures the pressure and temperature of the gearbox, and performs the mission equipment power command received from the mission computer. The PMU was designed to meet the requirements of the UAV, and was performed through structure/thermal analysis, environmental test, EMI test and ground/flight tests.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.5
• /
• pp.1769-1777
• /
• 2018

This paper proposes a method for optimal placement of Phasor Measurement Units (PMUs) considering system configuration and its attributes during the planning phase of PMU deployment. Each bus of the system is assessed on four diverse attributes; namely, redundancy of measurements, rotor angle and frequency monitoring of generator buses, reactive power deficiency, and maximum loading limit under transmission line outage contingency, and a consolidated 'degree of criticality' is determined using Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The major contribution of the proposed work is the development of modified objective function which incorporates values of the degree of criticality of buses. The problem is formulated as maximization of the aggregate degree of criticality of the system. The resultant PMU configuration extends complete observability of the system and majority of the PMUs are located on critical buses. As budgetary restrictions on utilities may not allow installation PMUs even at optimal locations in a single phase, multi-horizon deployment of PMUs is also addressed. The proposed approach is tested on IEEE 14-bus, IEEE 30-bus, New England (NE) 39-bus, IEEE 57-bus and IEEE 118-bus systems and compared with some existing methods.

• Proceedings of the KSRS Conference
• /
• 2002.10a
• /
• pp.228-228
• /
• 2002

The DLS(Data Link System) is located in the PDTS(Payload Data Transmission Subsystem) of KOMPSAT-II, and its main function is to provide communication link with Ground Segment as a space segment. DLS receive the data of MSC, OBC from DCSU(Data Compression Storage Unit) and transmit to the Ground Station by X-Band RF link. DLS is consist of CCU(Channel Coding Unit), QTX(QPSK Transmitter, ASU(Antenna Switch Unit) CCU makes a packet for communication after several kind of data processing such like Ciphering, RS Coding. QTX transmit PDTS data by OQPSK. Modulation. ASU is the unit for reliability of antenna switching. So, DLS's function is consists of ciphering, RS coding, CCSDS packetizing, randomizing, modulation and switching to antenna. These DLS's functions are controlled by PMU(Payload Management Unit). All commands to DLS are sent by PMU and all telemetries of DLS are sent to the PMU. The PMU receives commands from OBC and sends telemetries to the OBC. The OBC communicates with Ground Station by S-Band RF link. This paper presents the on-orbit DLS operation concept through the ground segment.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.33 no.6
• /
• pp.929-938
• /
• 2023

ARM processors, utilized in mobile devices, have integrated the hardware isolation framework, TrustZone technology, to implement two execution environments: the trusted domain "Secure World" and the untrusted domain "Normal World". Rootkit is a type of malicious software that gains administrative access and hide its presence to create backdoors. Detecting the presence of a rootkit in a Secure World is difficult since processes running within the Secure World have no memory access restrictions and are isolated. This paper proposes a technique that leverages the hardware based PMU(Performance Monitoring Unit) to measure events of the Secure World rootkit and to detect the rootkit using deep learning.

• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.593-596
• /
• 2005

The MSC is a remote sensing instrument with very high performance that is to be installed on KOMPSAT2 satellite. The MSC consists of EOS (Electro-Optic Subsystem), PMU (Payload Management Unit) and PDTS (Payload Data Transmission Subsystem). PMU controls and monitors all the other payload units by sending commands and collecting telemetry. PMU is in charge of interfacing between payload system and satellite bus system. PMU gets commands from ground-station via OBC (On-Board Computer) that is a main controller of the satellite bus system and sends telemetry to the ground-station via OBC. There is a processor module, called SBC (Single Board Computer) in the PMU. The SBC is a main controller of the MSC system. The main roles of the SBC are payload mission management, command validation and execution, telemetry collection and monitoring, ancillary data handling, event reporting, power control of payload sub-units and communication with these units. Intel's 80486DX2 processor has been used for the SBC. Due to the fact that the SBC plays important roles for imaging mission execution and handles a lot of control data that is required for payload operation, it is required to make analysis of the CPU load when it is in maximum operation mode. In this paper, the analysis and measurement results of the SBC throughput in the maximum operation mode.