• Journal of Sensor Science and Technology
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• v.17 no.4
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• pp.308-316
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• 2008

For the measurement of liquid level in ship's cargo tank, ballast tank, fuel oil tank and fresh water tank, several types of gauge meter are used such as tubular type, magnetic float type, reflex type transparent type and welding pad type. Among them, magnetic float type gauge meter is environmental friendly device because it is free of power source and maintenance. The main obstacle of the device is relatively large error bound. In this paper, finite element method is used to design and analysis of the magnetic float type gauge meter. The operation of reed switch according to the magnetic field has been successfully described and agreed well with experimental measurement. The optimum geometry with combination of permanent magnet and reed switches are designed to achieve 98 % accuracy of fluid level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2718-2721
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• 2011

This research developed a remote communication system for automatic water meter reading and charge calculation from the field of a house or apartment complexes within the same district. Developed system was applied to perform measurements of the pulse-sensing technology, the minimum power consumption, temperature compensation, short-range wireless communications technology, the handset and wireless communication capabilities of the DB management embedded software to efficiently control. Through this reading-related tasks that are required in a temporal, material and human resources can be minimized.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.3
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• pp.219-223
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• 2008

The dissolved oxygen (DO) sensors were fabricated by screen printing method, and potable dissolved oxygen measurement system was fabricated for low cost products. The fabricated sensors had high current change and fast response according to dissolved oxygen concentrations in the applied voltage of 0.7 V. The DO measurement system was consisted of MCV, amplifier, filter, power supply and display. DO concentrations were programed to display as digital percentages by converting the analog value. It is expected that the fabricated DO measurement system can replace the expensive commercial DO meter, because it reveals the high accuracy of ${\pm}0.5%$ to the standard solution and the response time of about 100 sec like the commercial DO meter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.4
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• pp.261-266
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• 2018

When the clamp meter approaches the electric path where current is flowing, leakage current can be measured at a distance from the electric current because the induced current increases as the magnitude of the current increases and approaches nearer to the electric path. Therefore, measurements were carried out from a distance to avoid this effect. In addition, the measured values differ depending on the location of the power line that penetrates the ZCT of the clamp meter, thus measurements were performed at a location where this effect was minimized. The fraction of compliant branch circuits, whose leakage current was lower than 1.00 mA, was found to be 69.0% out of the total of 439 branch circuits, while the percentage of compliant branch circuits having an insulation resistance higher than $0.20M{\Omega}$ was found to be 93.2%. The reason why the percentage of compliant branch circuits with low leakage current was low might be due to the inclusion of capacitive leakage current in the total measured leakage current.

• Journal of the Korea Society of Computer and Information
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• v.26 no.12
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• pp.143-150
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• 2021

In the recent power industry, a change is taking place from manual meter reading to remote meter reading using AMI(Advanced Metering Infrastructure). If such the power data generated from the AMI is recorded on the blockchain, integrity is guaranteed by preventing forgery and tampering. As data sharing becomes transparent, new business can be created. However, Ethereum blockchain is not suitable for processing large amounts of transactions due to the limitation of processing speed. As a solution to overcome such the limitation, various On/Off-Chain methods are being investigated. In this paper, we propose a interface server using data sharding as a solution for storing large amounts of power data in Etherium blockchain environments. Experimental results show that our power-data processing system with sharding method lessen the data omission rate to 0% that occurs when the transactions are transmitted to Ethereum and enhance the processing speed approximately 9 times.

• Proceedings of the KIEE Conference
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• 1986.07a
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• pp.185-187
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• 1986

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.2
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• pp.279-286
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• 2013

The recent power shortages due to surge in demand for electricity highlights the importance of smart grid technologies for efficient use of power. The experimental content for vulnerability against availability of smart meter, an essential component in smart grid networks, has been reported. Designing availability protection mechanism to boost the realization possibilities of the secure smart grid is essential. In this paper, we propose a mechanism to detect the availability infringement attack for smart meter and also to find anomaly nodes through analyzing smart grid structure and traffic patterns. The proposed detection mechanism uses approximate entropy technique to decrease the detection load and increase the detection rate with few samples and utilizes the signal information(CIR or RSSI, etc.) that the anomaly node can not be changed to find the anomaly nodes. Finally simulation results of proposed method show that the detection performance and the feasibility.

• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.712-719
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• 2013

This paper studies the security module for the reliable transmission of the meter reading and the control data between the remote terminals and the upper server-side in smart water grid. The proposed security module was implemented to make it attachable to the remote terminal without security function. In particular, unlike the smart grid of electric field, the low power is considered due to the use of battery power in the smart water grid, and the ARIA-GCM-128 symmetric key method is adopted taking into the account that the damp and constrictive environments by the installed meter location in the underground occur a communication obstacle on building of the large-scale network system. The encryption module of this paper was devised to ensure the safety between the reading data on the terminal and the control data from the upper server, and secure the stability of the remote meter reading system by taking protection against an arbitrary alteration or modification.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.4
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• pp.125-136
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• 2011

The vulnerabilities existed in Korean electricity control systems is unexposed because it is being operated in a closed network with superior security. The threat will become greater once the closed network develops into a smart grid environment with superior intelligence. Security will have a greater impact once each household will be connected to the power plant via the smart meter. This research focuses on stable data transfer in harsh external environment and whole-nation coverage network, and suggested standardized and optimized Virtual Private Network (VPN) Gateway architecture to support Power Line Communication (PLC). The functionality and stability of the prototype has been verified with field tests. For implementation of outdoor type VPN device for smart grid, we adopted PLC low voltage remote-meter-net for data communication. Also, IPSec type tunneling and ARIA algorithm based encryption of data collected by PLC low voltage remote meter is transmitted.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.2
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• pp.241-247
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• 1998

The hydraulic coupling is a kind of power transmission device combined with pump turbine and casing as its main parts. The purpose of this research is to construct an experimental test set-up and to establish an available soft ware for th characteristics of two domestically developed hydraulic couplings. The test item is torgue rpm. and slip and or efficiency characteristic in accordance with variation of oil quantity. in this case the oil quantity was varied 55%, 67% and 77% of the inside capacity of hydraulic copuling.