• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.799-800
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• 2013

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.6
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• pp.37-48
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• 2005

The efficiency of power supply circuits such as DC-DC converters and batteries varies on the trend of the power consumption because their efficiencies are not fixed. To analyze the efficiency of power supply circuits, we need the temporal behavior of the power consumption of the loads, which is dependent on the activity factors of the devices during the operation. Since it is not easy to model every detail of those factors, one of the most accurate power consumption analyses of power supply circuits is measurement of a real system, which is expensive and time consuming. In this paper, we introduce an active load emulator for embedded systems which is capable of power measurement, logging, replaying and synthesis. We adopt a pattern recognition technique for data compression in that long-term behaviors of power consumption consist of numbers of repetitions of short-term behaviors, and the number of short-term behaviors is generally limited to a small number. We also devise a heterogeneous structure of active load elements so that low-speed, high-current active load elements and high-speed, low-current active load elements may emulate large amount and fast changing power consumption of digital systems. For the performance evaluation of our load emulator, we demonstrate power measurement and emulation of a hard drive. As an application of our load emulator, it is used for the analysis of a DC-DC converter efficiency and for the verification of a low-power frequency scaling policy for a real-time task.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.2
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• pp.86-94
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• 2007

The NoC (network-on-chip) approach is a promising solution to the increasing complexity of on-chip communication problems because of its high scalability. But, NoC applications generally consume a lot of power, because they require a large design space to accommodate many parallel IPs and network communication channels. It is not easy to analyze the power consumption of NoC applications with conventional simulation methods using simple power models. In addition, there are also many limitations in using sophisticated simulation models because they require long execution time and large efforts. In this paper, we apply a cycle-accurate energy measurement technique and tool to the FPGA prototypes, which are generally used to verify the correctness of SoC designs, as a practical indication of the power consumption of real NoC applications. An NoC-based JPEG encoder implementation is used as a case study to demonstrate the effectiveness of our approach.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.7
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• pp.282-292
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• 2003

In this paper, we evaluate the performance of WCDMA reverse link receiver system with closed loop fast transmit power control (TPC). For fast power control, SIR must be measured precisely. We propose a new SIR measurement algorithm having a simple structure. The proposed algorithm uses unused OVSF code for interference power evaluation. The proposed SIR measurement algorithm is compared to the conventional SIR measurement algorithm in Ref.$^{［1］}$ under closed loop fast TPC. We adopted WMSA channel estimation filter with Κ=2 for mobile radio channel estimation and considered one slot TPC delay. Extensive computer simulation results show that the proposed algorithm using unused OVSF code reduces the required Ε$_{b}$ /Ι$_{0}$ at the BER of 10$^{-3}$ up to 0.9㏈ and has an improved TPC error performance compared to the conventional algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.5899-5905
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• 2014

Faults in electric power system can be a critical problem for vehicles. The system durability is determined mainly by the durability of their components and operating conditions. Monitoring the conditions of the electric power system may be necessary because it is very difficult to predict precisely when it will fail. Therefore, the aim of this study was to develop a diagnosis system for an electric power system of a vehicle. The alternator voltage, excitation voltage, lamp voltage, battery voltage, and engine rpm from a crank angle sensor are monitored continuously and the system fault can be then detected in real time. NI USB- 9201 DAQ and LabVIEW SW have been used to measure the voltages and analyze the data. Compared to conventional measurements for only each component, an integrated and portable measurement method was developed. In addition to the monitoring the electric power system in real time, the saved data from the measurement also provides valuable information to improve the durability of the components.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.2
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• pp.81-86
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• 2013

In this paper, the parameter identification for localization scheme for the optics-based micro sensor node is conducted. We analyzed short measurement range problem which can be occurred in optical based micro sensor node localization method using a time of flight. And we set up the theory for distance and maximum reflected laser power to overcome the problem by identifying hardware parameters like laser power, effective area of MEMS CCR, sensitivity of photodetector, and so on. Experimental results of measurement of maximum reflected laser power were compared with results of the theory. By using the theory, we can identify hardware parameters of localization scheme to measure particular position of the optics-based micro sensor node.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.135-141
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• 2002

A study on measurement of refractive power for eyesight by condition of opposite color, has been conducted. In the results of the test, it was observed that farsightedness has better lightness large range. However, in the case of chroma, we cannot distinguish tell the nearsightedness from the farsightedness. Generally, refractive power increased with the increase of large range was revealed. This method is better as compared with red-green test method.

• Journal of Power System Engineering
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• v.19 no.2
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• pp.33-39
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• 2015

In conducting indoor positioning by code division multiple access using spread spectrum ultrasonic waves, it is required to detect signals under the influence of near-far problem occurred by difference on signal power, caused by distance between transmitter and receiver. For discussing robustness to the problem, we verified measuring accuracy on distance from an experiment on a real space with a hardware device where our proposed method is mounted. The proposed method performs automatic signal detection by setting threshold level dynamically. As an experimental result, measurable distance were improved by the proposed method, and measurement errors were up to 50mm in distances from 1000mm to 6000mm; therefore, enough accuracy to realize self-localization or navigation for autonomous mobile robot or human was obtained.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.617-620
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• 2007

The performance evaluation of the Samcheonpo small-hydropower plant constructed on the October 25th,2006, was carried out focused on the turbine and generator efficiency analysis by using the measurement data. The unreasonable and unrealistic efficiency results are occurred in some periods because of the data variability, uncertainty, and measurement errors and mistakes. Whereas, the big mismatch is the tidal elevation predicted in the design processes. The difference between the measured and estimated tidal elevation is obvious during the low water period. It should be considered and checked in depth on the efficiency analysis of the planned and constructing small-hydro power plants in other coastal areas.

• 전기의세계
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• v.13 no.3
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• pp.28-37
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• 1964

It is the intention of this thesis to discriminate and investigate the cause of the shaft vibration of the vertical type hydroelectric power generator with respect to electrical, mechanical and hydraulic aspects, and to analyze the vibration which will occure by the each cause investigated above. In order to test the shaft vibration of No.1 generator in Hwachon, Korea new measurement method and measuring equipments were designed. In practice the shaft vibration of the generator was measured by above equipments and analyzed by the discriminative method. Detailed explanation for the designed measurement method and instruments is presented, and the results which I had tested three times for the generator No.1 in Hwachon power plant are added. As a appendix the mechanism and causes of the thrust bearing's wear and remarks for the runner are written.