• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.18 no.6
• /
• pp.187-193
• /
• 2018

There has been a gradual increase in the demand for the electric power in Korea. In order to meet the demand, power station should have technical functions with increased effectiveness. When accident happens in electric machinery at power stations, huge amount of economic losses and mulfunction of equipments occur. One of the accidents is a deteriorated cables operating power stations. In order to prevent cable accident in advance, we should monitor the insulation status of the cable. Cable accidents are resulting from the junctions. We have developed and installed a device in order to identify the status of junction part of power cable at Korea Western Power Co., Ltd.. We performed an accurate diagnosis for the stable utilization of junctions where the accidents occurs most frequently, and to increase the reliability. In this paper, we present the concepts of our device and the method of monitoring diagnosis for the stable use of junctions at cables predicting the life time of cables by analyzing the data obtained by the device. We also present the hardware aspect of the device we have developed.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1556-1557
• /
• 2011

변압기의 고체 절연이 열화 되거나 불순물 및 수분이 혼입되어 임계치 이상의 고전계가 인가되면 결합부분에서 부분방전이 발생한다. 현재 변압기에서 부분방전을 검출하기 위해서는 부싱탭을 이용하거나 전류센서, 초음파센서 등을 이용하여 부분방전을 검출하고 있지만 전기적인 부싱탭이나 전류센서를 이용한 검출 방법은 주변 잡음의 영향을 많이 받고 초음파법은 감도가 낮다는 단점을 가지고 있다. 이에, UHF 방식을 이용한 부분방전 검출 기술이 전력기기의 초기 고장진단을 발견하는 효과적인 방법으로 인식되고 있다. 최근에는 이러한 UHF 진단방식의 높은 감도, 외부노이즈에 대한 적은 영향, 온라인 측정의 가능성의 장점으로 전력용 변압기에도 적용되고 있다. 본 논문에서는 전력 변압기에서 PD 진단에 적합한 UHF 센서의 개발에 대해서 소개한다. 제안된 UHF 센서는 광대역(500 ~ 1,500MHz)에서 측정이 가능하며 감도가 우수하며 특정 대역에서 공진점을 가지는 다중 공진 모노폴 안테나 타입이다. 안테나 시뮬레이션 및 해석을 통해 유중 부분방전을 모의하여 감도 측정을 실시한 결과 제안된 UHF 센서가 전력용 변압기의 부분방전 측정에서 높은 감도를 나타냈으며, 기존 측정 방식의 단점을 보완할 수 있는 방안으로서 전자파를 이용한 부분방전 측정에 대한 기초연구를 실시하여 변압기 운전중에 전자파 측정에 의한 부분방전 감시가 가능한 것으로 나타났다.

• Journal of the Korean Society of Safety
• /
• v.33 no.3
• /
• pp.27-32
• /
• 2018

Nowadays, to prevent electrical accidents in Korea, inspectors directly performed checking general electrical facilities as a cycle from every one to three years. It is difficult to presuppose an omen because intact conditions of electrical equipments are not kept at the time of inspection. In this paper, in order to ensure effectiveness of an online basis electric inspection, we developed an electrical safety IoT system using LoRa communication technology to enable monitoring mainly electrical safety components such as overcurrent, overvoltage, resistive leakage current, and power. Then we proposed a method for verifying performances of the prosed electrical safety IoT system. Resistive leakage currents are calculated by using difference of phase between voltages and currents. We verified that average errors are 0.97%, which reference goal is ${\pm}5%$ for a device, through reliability test according to conditions. Results of this research can be used as basic study materials to develop technologies for measuring three phase leakage current and for implementing public electrical safety. platform.

• Proceedings of the Korea Information Assurance Society Conference
• /
• 2004.05a
• /
• pp.275-282
• /
• 2004

As the logistic environment of digital contents is rapidly changing, the protection of the digital rights for digital content has been recognized as one of critical issues. Digital Right Management(DRM) has taken much interest Internet Service Provider(ISP), authors and publishers of digital content as an interested approach to create a trusted environment for access and use of digital resources. This paper propose an interested digital rights protection scheme using license agent to address problems facing contemporary DRM approached : static digital rights management, and limited application to on-line environment. We introduce a dynamic mission control technology to realize dynamic digital rights management. And we incorporate license agent to on- and off-line monitoring and tracking. The proposed system prevent illegal access and use by using PBD security method real time action monitoring for user, data security for itself.

• Journal of Ocean Engineering and Technology
• /
• v.13 no.3B
• /
• pp.73-82
• /
• 1999

In this research, an experimental study is presented to check the possibilities of offshore structures monitoring using AE techniques. The underwater transducer and preamplifier are fabricated. And, it is proved that this unit can be used for the detection of AE in offshore structures. Wave propagation studies have shown that supplementary attenuations due to seawater are significantly reducing the detection range of the sensors. It excludes the possibility of offshore structures monitoring with a small number of sensors. We conclude that AE waves would be correctly detected for a path of about 3m. Tubular joints have been tested in air and underwater using simulated elastic wave. Ability of AE techniques to detect and locate cracks early in their evolution has been demonstrated. Several parameters of AE generation have been set in evidence. It has also been shown that crack development goes with an increase of AE parameter. Conclusively, it is shown that AE techniques can provide practical alternatives to present methods being used for inspection of deep-water offshore structures undergoing structural degradation due to fatigue crack growth.

• Proceedings of the KIEE Conference
• /
• 2000.11a
• /
• pp.177-179
• /
• 2000

In this paper, we developed the online Monitoring & Diagnostic(MD) system of distribution transformers. It consists of the Data Acquisition(DA) module and the DataBase(DB) module. The acquired data from the distribution transformers is stored to the DB in an on-line. The DB is planned and made to the RDBMS (Relative DataBase Management System) to manage the data efficiently. The developed MD system estimates the loss of life from the DB. Thus, it could be managed the career and the functional lifetime of the transformer more efficiently than existing systems. In the case study, the oil temperature rising experiment is performed by using the back loading method in the laboratory level. From the results, the proposed MB system can be a practical applications for the distribution transformers.

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.11
• /
• pp.148-154
• /
• 2001

Drilling is one of the most important operations in machining industry and usually the most efficient and economical method of cutting a hole in metal. From automobile parts to aircraft components, almost every manufactured product requires that holes are to be drilled for the purpose of assembly, creation of fluid passages, and so on. It is therefore desirable to monitor drill wear and hole quality changes during the hole drilling process. One important aspect in controlling the drilling process is monitoring drill wear status. A drill-wear monitoring system provides information about drill status. With the information, optimum planning for tool change is possible. And drill-wear monitoring system in needed to evaluated drilled hole quality and the wear of drill. Accordingly, this paper deals with an on-line drill wear monitoring system of the detection of tool wear with the computer vision and the area of the drill flank wear is analyzed quantitatively by the system.

• Water for future
• /
• v.29 no.2
• /
• pp.167-178
• /
• 1996

In designing automatic water quality monitoring networks for a river basin, determination of measurement locations and items is critical to the effectiveness of the total system. In this paper we studied how to decide these two design factors when a monitoring network is designed for the purposse of water quality surveillance and emergency alarm. For measurement locations, candidate sites are chosen based on the intake amount for water supply and the point sources of contamination. Then, detailed locations are decided according to the contaminant flow distance. As for measurement items, characteristics and the accident history of water pollution in the basin must be taken into account. Considering economic aspects, we proposed a two-stage measurement plan: basic components for all locations and selective ones variable for different locations. Proposed methodology is demonstrated through a case study for Nak-dong River Basin.

• Proceedings of the KIEE Conference
• /
• 2001.07a
• /
• pp.464-466
• /
• 2001

In this paper, we developed the on-line Data Aquisition System(DAS) of distribution transformers using the hardware and monitoring program. The DAS consists of the top oil temperature sensing part, ambient temperature sensing part, load current sensing part, acoustic emission peak-value sensing part, acoustic emission pulse counter part, micro-processor part and wireless communication part. The Monitoring System consists of the communication setting, online monitoring and database construction part. The DAS send the data acquired from the some sensors of the distribution transformers to the host PC. The monitoring program of the host PC stores the data to database. And the monitoring system estimates the loss of life time for distribution transformer from the DB. Thus, it could be managed the career and the functional lifetime of the transformer more efficiently than existing methodologies.

• Journal of the Korean Data and Information Science Society
• /
• v.21 no.6
• /
• pp.1125-1136
• /
• 2010

Lately there exist increasing demands for online abnormality monitoring over trajectory stream, which are obtained from moving object tracking devices. This problem is challenging due to the requirement of high speed data processing within limited space cost. In this paper, we present a FADA (Fuzzy Anomaly Detection Algorithm) which constructs normal profile by computing mobility feature information from the GPS (Global Positioning System) logs of mobile devices in MANETs (Mobile Ad-hoc Networks), computes a fuzzy dissimilarity between the current mobility feature information of the mobile device and the mobility feature information in the normal profile, and detects effectively the anomaly behaviors of mobile devices on the basis of the computed fuzzy dissimilarity. The performance of proposed FADA is evaluated through simulation.