The smart grid was initially developed to facilitate communication between operators of the electric power system (such as power generation companies and transmission system operators) and consumers within the distribution network. To implement the smart grid paradigm, time-synchronized measurement devices were developed and introduced into the electric power system. Phasor measurement units (PMUs) and waveform measurement units (WMUs) were created for wide-area transmission networks (at the high-voltage layer), while micro-PMUs were introduced for real-time state estimation in distribution networks (at the low-voltage layer). These time-synchronized measurement devices allow power system operators to monitor the operational status of power generation, transmission, and distribution infrastructure in real time. In particular, data-driven applications utilizing the measurement data can intelligentize and advance the monitoring, operation, and control of the smart grid. The capabilities of digitized high-resolution measurement and time-synchronization are the key factors that enable these contributions to the smart grid. This paper provides an introduction to time-synchronized measurement devices, outlines their specific capabilities, and explores the data-driven applications that can be implemented for advanced smart grid monitoring systems.

Recently, as various damages are expected due to the risk of falling space debris, many studies are being carried out to acquire space object information. In this research, an optical-based space object surveillance system was developed to acquire information about space objects. To acquire orbit information by photographing a space object with this system, the accuracy of position data of the space object is important. The telescope coordinate is located in the 2D CCD plane of the telescope, and the space objects are in the celestial coordinate. The two coordinates have a non-linear relation caused by a deflection of the mechanical system, a scattering of the atmosphere and so on. In this study, we propose an alignment method for two coordinate systems. First, a model that analyzes the geometric relation between the telescope system on earth and space objects is explained. Then, we also propose a second model with the addition of correction parameters. As a result of performing coordinate alignment according to the method and procedure proposed in this study, the pointing accuracy is lowered below 3 arcsec.

The cutting force signal has traditionally served as a reference in conducting the monitoring studies using a variety of sensors to identify the cutting phenomena. There have been continuing studies on how to monitor the cutting force indirectly. It is because it is easier to access when considering an application to the actual machining site. This paper discusses a method of indirectly monitoring the cutting force using the feed drive current to analyze the change in the trend of the cutting force over the lapse of machining time. This enables the analysis of the cutting force by separating it in the X and Y axes of the machining plane. To increase the discrimination of the signal related to the actual cutting phenomenon from the feed drive current signal, a bandpass filter was applied based on the tooth passing frequency. The relationship between the feed drive current and the cutting force analyzed from the machining signal of actual machining conditions was applied to convert the feed drive current into the cutting force. It has been verified through experiments that the cutting load can be estimated with markedly high accuracy as a physical quantity of force from the feed motor current.

Recently, carbon fiber-reinforced plastic (CFRP) has been attracting much attention in various industries because of its beneficial properties such as excellent strength, modulus per unit density, and anti-corrosion properties. However, there are several issues in its application to various fields. Severe tool wear issues in its machining have been noted as one of the most serious problems because it induces various serious machining failures such as delamination and splintering. In this regard, timely tool replacement is essential for reducing the influence of tool wear. In this study, tool wear, especially flank wear, in the CFRP drilling was investigated and monitored. First, the reproducibility of tool wear under the same machining condition was experimentally evaluated. And it is demonstrated that tool wear may remarkably differ even though the same machining condition is applied to the tools. Then, tool wear monitoring based on the feed motor torque was applied to the detection of tool life ending in the CFRP drilling process. Consequently, it was demonstrated that the average and maximum detection error of the tool life end were less than 7 and 14%, respectively.

Tool wear is an essential parameter in determining tool life, machining quality and productivity. Current or power signals from motor drivers in machine have been used to estimate tool wear. However, accuracy of tool wear estimation was not enough to measure the amount of tool wear. In this study, flank wear of a drill tool was measured using vision sensor module which has zoom lens, CCD camera and image processing technique. The vision module was set up in the machine tool. Therefore, the image was acquired without ejecting the tool from the machine. Image processing techniques were used to define the cutting edge shape, tool diameter, and the wear edge on cutting rips with the proposed measuring algorithm. The automatically calculated wear value was compared with a manually measured value. As a result, the difference between the manual and the automatic methods was below 4.7%. The proposed method has an advantage to decrease the measuring time and improve measuring repeatability because the tool is measured holding chuck in a spindle.