• Proceedings of the IEEK Conference
• /
• 2002.07c
• /
• pp.1499-1502
• /
• 2002

A method for acquiring an environmental map by integrating distance data obtained by sonars of a moving robot with web interface is proposed. Sonar data contains outliers in some cases such as ultrasonic beam is projected onto a corner of an object. Therefore, the influence of the outliers should be reduced by detecting outliers. In our method, the outliers are detected by two ways: (i) a method considering geometrical .elation among the observed surface and the projected ultrasonic beau, and (ii) a method considering consistency with data obtained by other sonars. By measurement by the sonar, the distance from the sonar to the obstacle is obtained. Assuming the two dimensional space we can know that the inside of the sector, whose renter coincide with the sonar and whose radius is equal to the obtained distance, is the free area, and a part of the arc of this sector is the obstacle area. The generation of the environmental map is done by integrating the free area and the obstacle area obtained by each measurement by the sonars. Before the integration, the outliers detection is done by two ways mentioned above. Experimental results show that obtained maps obtained by our methods with outliers defection are much better than those by a method without outliers detection.

• Proceedings of the KIEE Conference
• /
• 2001.07d
• /
• pp.2184-2186
• /
• 2001

The research presented in this paper focuses on a method for the detection of High Impedance Fault(HIF). The method will use the fast wavelet transform and neural network system. HIF on the multi-grounded three-phase four-wires primary distribution power system cannot be detected effectively by existing over current sensing devices. These paper describes the application of fast wavelet transform to the various HIF data. These data were measured in actual 22.9kV distribution system. Wavelet transform analysis gives the frequency and time-scale information. The neural network system as a fault detector was trained to discriminate HIF from the normal status by a gradient descent method. The proposed method performed very well by proving the right state when it was applied staged fault data and normal load mimics HIF, such as arc-welder.

• Journal of Sensor Science and Technology
• /
• v.32 no.4
• /
• pp.219-222
• /
• 2023

Partial discharges (PD) have long been recognized as a major contributing factor to catastrophic failures in high-power equipment. As the demand for high voltage direct current (HVDC) facilities continues to rise, the significance of on-line and real-time monitoring of PD becomes increasingly prominent. In this study, we have designed, fabricated, and characterized a highly sensitive and cost-effective PD sensor comprising a pair of copper electrodes with different arc lengths. The key advantage of our sensor is its non-invasive nature, as it can be installed at any location along the entire power cable without requiring structural modifications. In contrast, conventional PD sensors are typically limited to installation at cable terminals or insulation joint boxes, often necessitating invasive alterations. Our PD sensor demonstrates exceptional accuracy in estimating PD location, with a success rate exceeding 95% in the straight sections of the power cable and surpassing 89% in curved sections. These remarkable characteristics indicate its high potential for realtime and on-line detection of PD.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.2164-2165
• /
• 2011

본 논문에서는 직렬아크 고장 시 발생하는 전류파형의 특징인 전류의 shoulder의 검출을 통하여 아크고장을 판별하는 직렬아크 고장 검출기를 제안하였다. 또한 정상적인 동작에서 발생하는 전류의 shoulder를 아크신호로 판단하지 않기 위한 방법을 제안 하였으며 이를 시뮬레이션을 통해 확인하였다.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.1274-1279
• /
• 2004

This paper proposes technique to detect ground fault in railway high voltage distribution lines. Overcurrent relay technique is widely used for detecting one line ground fault that occurs most frequently in railway high voltage distribution lines. However, ground fault in distribution line is usually high impedance fault with arc. Because the fault current magnitude measured in substation is very small, the conventional overcurrent relay can't detect the high impedance ground fault. Therefore this paper proposes the advanced technique using wavelet transform. It extracts D1 component from fault signals and detects fault comparing magnitude of D1 component in each phase. To evaluate this proposed technique, we model distribution system using PSCAD/EMTDC and extract various fault data. In conclusion this technique can detect ground fault including high impedance fault regardless of fault distance, fault impedance etc.

• Journal of Institute of Control, Robotics and Systems
• /
• v.9 no.3
• /
• pp.251-258
• /
• 2003

Optical Switching Matrix (OSM) or Optical Multistage Interconnection Networks (OMINs) comprising photonic switches have been studied extensively as important interconnecting blocks for Optical Cross Connects (OXC) based on Optical Burst Switching (OBS). A basic element of photonic switching networks is a 2$\times$2 directional coupler with two inputs and two outputs. This paper is concerned with the diagnosis of multiple crosstalk-faults in OSM. As the network size becomes larger in these days, the conventional diagnosis methods based on tests and simulation become inefficient, or even more impractical. We propose a simple and easily implementable algorithm for detection and isolation of the multiple crosstalk-faults in OSM. Specifically. we develop an algorithm for isolation of the source fault in switching elements whenever the multiple crosstalk-faults arc detected in OSM. The proposed algorithm is illustrated by an example of 16$\times$16 OSM.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.866-867
• /
• 2015

화재 및 인명사고의 약 40%이상이 아크플래시사고로 인한 원인으로 밝혀지고 있다. 이에 아크 플래시 발생으로 인한 2차 사고 방지가 산업 경제적 측면에서 중요하다고 판단하여 본 연구에서는 초고속자외선 검출 시스템을 구현하였다. 아크 플래시 신호를 광파이버 포인트 센서 및 광섬유 루프센서를 이용하여 초고속 광검출 및 고속 신호처리 컨트롤러를 이용해 차단기 트립 개시 신호 출력까지 시간을 1.5ms 이내로 출력하는 것을 목표로 하였으며 테스트베드를 통해 구축한 시스템에서 아크 발생 후 소요시간 약 1ms의 트립 개시 신호를 출력하는 초고속 아크 검출 시스템을 개발하였다.

• Proceedings of the KIPE Conference
• /
• 2015.07a
• /
• pp.427-428
• /
• 2015

본 논문은 DC 배전시스템 내에서 발생할 수 있는 직렬 DC 아크 고장을 검출하기 위한 알고리즘을 제안한다. 직렬 DC 아크 고장은 동일 전위의 도선 또는 접속점의 노화 등으로 인해 발생하며, 아크 고장 에너지의 크기에 따라 수초 이내에 화재 사고를 유발할 수 있기 때문에 정확한 고장 검출을 통한 빠른 제거가 필요하다. 스위칭 전력변환 장치에서 발생하는 노이즈 성분에 의한 검출 알고리즘의 오동작 현상을 제거하기 위해 시간 영역에서의 전류 변화와 주파수 영역에서의 전류 크기 차이를 동시에 이용하여 직렬 DC 아크 고장 발생여부를 검출하게 된다. 제안 알고리즘은 5kW급 용량의 380V 저전압 DC 배전 시스템을 대상으로 검증하였다.

• Journal of Korea Society of Industrial Information Systems
• /
• v.7 no.4
• /
• pp.29-36
• /
• 2002

In this paper, a new edge detection method for area images is presented based on the scan-line image segmentation technology. The existing algorithms are lack of precision in its detections due to the noise factors such as depth perception and illumination problems when processing the 3D image into a 2D image. The general process of applying the scan-line method is to extract straight line components to determine the shape of the objects. However, we implement this method to an arc curve for precise detections. the paper proved precise detections that from off line to on line.

• Journal of Astronomy and Space Sciences
• /
• v.32 no.3
• /
• pp.237-245
• /
• 2015

A strategy is needed for a regional survey of geosynchronous orbits (GSOs) to monitor known space objects and detect uncataloged space objects. On the basis of the Inter-Agency Debris Committee's recommendation regarding the protected region of geosynchronous Earth orbit (GEO), target satellites with perigee and apogee of $GEO{\pm}200km$ and various inclinations are selected for analysis. The status of the GSO region was analyzed using the satellite distribution based on the orbital characteristics in publicly available two-line element data. Natural perturbation effects cause inactive satellites to drift to two stable longitudinal points. Active satellites usually maintain the designed positions as a result of regular or irregular maneuver operations against their natural drift. To analyze the detection rate of a single optical telescope, 152 out of 412 active satellites and 135 out of 288 inactive satellites in the GSO region were selected on the basis of their visibility at the observation site in Daejeon, Korea. By using various vertical view ranges and various numbers of observations of the GSO region, the detection efficiencies were analyzed for a single night, and the numbers of follow-up observations were determined. The orbital estimation accuracies were also checked using the arc length and number of observed data points to maintain the GSO satellite catalog.