• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.490-493
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• 1999

Due to the miniaturization of electrical components and assembles on signal and telecommunication circuits, transient overvoltages caused by switching operation or lightning surge has become more interesting concern to the field of electrical engineering. This paper describes the development of transient voltage blocking devices (TBDs) that can protect sensitive signal and telecommunication devices from overvoltages. Two kinds of TBDs are designed and tested by using a combination surge generator which can produce the standard impulse current of 8/20${\mu}$s 2.1kA according to the IEC 1000-4-5 standard. From the simulation and experimental reults, it is confirmed that the proposed TBD has an enough protection performance in low insertion loss and tight clamping voltage.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.91-96
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• 2015

There are provision for risk analysis in IEC standards. It is to determine the need for installation of a surge protection device (SPD) in order to protect the low-voltage electrical installations from overvoltages caused by atmospheric phenomena and the like. However, scattered many related standards, the lack of details are not easy to apply it in the field. We investigated the relevant domestic and international standards for applies to the international standards in domestic. And we proposed the flow chart for determining the need for protection of the low-voltage electrical installations from overvoltage due to atmospheric phenomena and it set the appling target facility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.991-994
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• 2007

Recently, there has been major issue in safety of elevator. In the view of safe management of elevator, the corresponding research must be done since accidents related elevator include not only actual accident but also possible accident in order to protect user from dangerousness. This research aims to seek an analytical solution for safety apparatus which caused accident again and again among dangerous factors of an elevator. In order to assure safety of door, ANSYS, a commercial software was applied and evaluate safety qualitatively by calculating stress and strain deformed under the loads of 40 to 100kg.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.154-155
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• 2012

The dynamic voltage restorer (DVR) is an effective protection device for wind turbine generator based on doubly-fed induction generator (DFIG) operated under the unbalanced voltage dip conditions. The compensating voltages of DVR depend on the voltage dips and on the influence of the zero sequence components. If the $Y_0/{\Delta}$ step-up transformers are used, there are no zero sequence components on the DFIG side. However, if the $Y_0/Y_0$ step-up transformers are used, the zero sequence components will appear during faults. The zero sequence components result in the high insulation costs and the asymmetric of the terminal voltages. This paper proposes a method for controlling zero sequence components in DVR to protect DFIG under unbalanced voltage dips. Simulation results are presented to verify the effectiveness of the proposed control method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.966-973
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• 2012

In microgrid demonstration site, distributed generations can make bidirectional power flows on the system. If an accident occurs, the fault current from the inverter based distributed generation is small. However, the conventional protection scheme in distribution network is designed to operate at high fault current. This means that the traditional protection of distribution network is no longer applicable and new protection methods must be developed. In this paper, for two cases, algorithms for protection coordination of demonstration site is proposed and verified through PSCAD/EMTDC simulation. In first case, protection devices are assumed to have the abilities of directional relaying and communication. In second case, protection devices do not have those abilities. Proposed protection coordination algorithms detect the fault locations and protect the microgrid fairly well.

• Journal of Information Technology Services
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• v.18 no.1
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• pp.141-151
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• 2019

To protect workers from industrial accidents, IoT hazard detection system using LoRa network was designed and fabricated. LoRa networks can operate with low power consumption, wide coverage, and low usage fees. The hazard detection system consists of a sensor unit, a transceiver module, a LoRa base station, ThingPlug, and a monitoring device. We have designed an optimal risk-determining algorithm that can send information quickly in a working environment. As measured by TTA, the implemented system has been found to be able to deliver the worker's location, ambient temperature, and carbon monoxide density to the administrator through the user interface. The implemented system showed a bit rate of 290bps and a maximum application range of 6 km.

• Journal of Sensor Science and Technology
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• v.31 no.5
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• pp.286-292
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• 2022

As mobile electronics become smarter, higher-level security systems are necessary to protect private information and property from hackers. For this, biometric authentication systems have been widely studied, where the recognition of unique biological traits of an individual, such as the face, iris, fingerprint, and voice, is required to operate the device. Among them, ultrasound fingerprint imaging technology using piezoelectric materials is one of the most promising approaches adopted by Samsung Galaxy smartphones. In this review, we summarize the recent progress on piezoelectric ultrasound micro-electro-mechanical systems (MEMS) transducers with various piezoelectric materials and provide insights to achieve the highest-level biometric authentication system for mobile electronics.

• Journal of the Semiconductor & Display Technology
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• v.23 no.2
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• pp.28-32
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• 2024

The personal mobility Sharing service is currently active. Especially, electric scooters are widely utilized because they can move comfortably at a high speed over a short distance with a simple driving method. Its driving method is easy, but there is no protection device to protect the bare body. So, there is a greater accident than other means of transportation, and if two people are on board, there is higher accident probability. However, since there is no specific ways to prevent multi-person boarding yet, we propose a multi-person boarding detection model using tilt and pressure sensor. The proposed method measures the tilt degree and direction by using a tilt sensor installed in the center of the board plate and detects multi-people riding.

• The Journal of Society for e-Business Studies
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• v.11 no.2
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• pp.13-30
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• 2006

Web services are independent on a platform and are suitable in the Ubiquitous environment which an interaction for each device. Ubiquitous web services can use various applied service in any network neighborhood or terminal. Main characteristic of Ubiquitous is context-awareness. Therefore, Ubiquitous web services must include context-aware control process and protect user privacy because context-aware environment collects privacy data. But current web services standard is not specially designed in respect of context-communication. Therefore, the framework which can add flexibility in transmission of context is required. Our Framework can give extension for context and can communicate flexibly Context information for every session. Therefore, Our Framework can solve overhead problem of context in SOAP message and protect user's privacy according to user preference.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.6
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• pp.504-511
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• 2013

This paper proposes improved detection schemes for concealed micro-electronic devices using clustering and classification of radio frequency harmonics in order to protect intellectual property rights. In general, if a radio wave with a specific fundamental frequency is propagated from the transmitter of a classifier to a concealed object, the second and the third harmonics will be returned as the radio wave is reflected. Using this principle, we exploit the fuzzy c-means clustering and the ${\kappa}$-nearest neighbor classification for detecting diverse concealed objects. Simulation results indicate that the proposed scheme can detect electronic devices and metal devices in various learning environments by efficient classification. Thus, the proposed schemes can be utilized as an effective detection method for concealed micro-electronic device to protect intellectual property rights.