• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.05a
• /
• pp.1265-1266
• /
• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.05a
• /
• pp.1237-1238
• /
• 2010

• Proceedings of the KIEE Conference
• /
• 2002.11a
• /
• pp.102-105
• /
• 2002

ADSS(All Dielectirc Self-Supporting) cable installed under high voltage power cable line suffers a variety of environmental influence, rain, wind, snow fall, chemical pollution, salt fog and electrical stress. Its lifetime is required to be at least 20 years with this harsh weathering condition. The electrical stress under high voltage power line gives rise to dry band arcing and tracking, the severest damage, on the outer sheath of cable. Finally tracking might penetrate sheath and cause the break-down of ADSS cable. Tracking resistant sheath material, therefore, should be used to protect the core of ADSS from dry band arcing and to be sure long lifetime. In this work, we discuss various commercial tracking resistant material to investigate the way of track resistance and compare their mechanical, electrical, weathering and tracking properties through serial experiments. We found track resistant material is categorized into two main type : polyethylene with metal hydroxide and polyethylene with reduced carbon black. The Liquid contaminant, Inclined plane Tracking and Erosion test says the time to track of tracking resistant material with metal hydroxide has a little longer time to track in the high applied voltage than that with carbon black, but mechanical and weathering properties were inferior to.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.2
• /
• pp.1-7
• /
• 2018

Suspension bridge cables made of high strength steel wires require periodical maintenance in accordance with the axial force of cable-band bolts, since the bolts in suspension bridges can undergo tension decrease due to creep of cable wires, bolt relaxation, load fluctuation, and cable re-arrangement, etc. Consequently, this study is aimed at investigating and subsequently evaluating the critical factors with respect to the bolt tension-decrease phenomenon in SR suspension bridge in Korea, based on field monitoring, theoretical studies, and field record management works. From the observation, it is interesting to note that the decrease in the bolt tension force is typically accompanied by plastic deformation of the zinc plating layers in the cable wires. In addition, a framework corresponding to generic methodologies to characterize the deformation in terms of the bolt tension-decrease and long-term history management has been developed in this exploratory study.

• Proceedings of the KIEE Conference
• /
• 2005.07e
• /
• pp.127-129
• /
• 2005

OPGW(Optical Ground Wire) whose demand is increasing worldwide have composite function as optical communication and grounding for preventing transmission line from lightning. While continuous efforts have been made to increase the transmission capacity and speed, the working method to replace the existing ground wire with OPGW under live-line condition is coming to force newly as installation aspects. Particularly, this requirement became more serious in developing country that the electric power supply is not sufficient and power outage is impossible for supply and dead of electric power LS cable Ltd. has developed the new installation method in full live-line condition to solve the confronted problem and to meet the market demand. In this paper, Electric Problems in live-line installation is considered to predict dry-band arcing. This can be used by Makers to predict dry-band arcing in insulating ropes installed on earth wire of power transmission system.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.433-435
• /
• 2004

본 논문에서는 기존의 가공지선(GW, Ground Wire)을 OPGW(Optical Ground Wire)로 교체공사를 할 경우 나타나는 절연로프에서의 건조대 아크현상을 수치적인 모델링를 통하여 해석할 수 있는 프로그램을 제작하고 현장조건을 입력하여 문제점을 판단하고 해결할 수 있는 방안을 제시하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.1
• /
• pp.27-32
• /
• 2008

In the signals-shadowed areas, In order to providing the suitable signals reception level repeaters are used for relay the signals. Repeater receives the weak signals and amplifies it up to required power level, The amplified signals get radiated by the various methods. Both antenna distribution and LCX(Leakage Coaxial Cable) are typical methods in the repeater and BTS signals radiation. Their applications are depended on the environment condition and frequency band. Generally the antenna distribution are used for the mobile telecommunication networks which use the higher frequency band than 500MHz. On the other side, LCX distribution is suitable to the frequency band under 500MHz. The network plan of repeater in FM, T-DMB, Fire Radio and Internal subway communication network are the typical LCX application fields. Cell planning with repeaters are based on the free space loss, LCX connection loss and actual field data. The actual field data can be the most important factor to design the network planning.

• Proceedings of the IEEK Conference
• /
• 2001.06b
• /
• pp.101-104
• /
• 2001

In this paper, we have analyzed algorithm about physical layer, data link layer and MAC layer of out-of-band specified in the DVS 178 and designed architecture of Out-of-band processor. Out-of-band processor extracts session key information from EMM packet to descramble MPEG-2 TS packet scrambled. Also, analyze EAS Packet including emergency alert information to provide emergency communications such as national emergency. In this paper, we have implemented prototype board for out-of-band processor.

• Structural Monitoring and Maintenance
• /
• v.9 no.2
• /
• pp.179-200
• /
• 2022

This paper proposes a data-driven methodology for online early damage identification under changing environmental conditions. The proposed method relies on two data analysis methods: feature-based method and hybrid principal component analysis (PCA) and kernel PCA to separate damage from environmental influences. First, spectral sub-band features, namely, spectral sub-band centroids (SSCs) and log spectral sub-band energies (LSSEs), are proposed as damage-sensitive features to extract damage information from measured structural responses. Second, hybrid modeling by integrating PCA and kernel PCA is performed on the spectral sub-band feature matrix for data normalization to extract both linear and nonlinear features for nonlinear procedure monitoring. After feature normalization, suppressing environmental effects, the control charts (Hotelling T² and SPE statistics) is implemented to novelty detection and distinguish damage in structures. The hybrid PCA-KPCA technique is compared to KPCA by applying support vector machine (SVM) to evaluate the effectiveness of its performance in detecting damage. The proposed method is verified through numerical and full-scale studies (a Bridge Health Monitoring (BHM) Benchmark Problem and a cable-stayed bridge in China). The results demonstrate that the proposed method can detect the structural damage accurately and reduce false alarms by suppressing the effects and interference of environmental variations.

• Journal of Electrical Engineering and Technology
• /
• v.3 no.3
• /
• pp.422-429
• /
• 2008

This paper presents compact low frequency ultra-wide band (UWB) sensor design and study of the partial discharge diagnosis by sensing electromagnetic pulse emitted from the partial discharge source with the newly designed UWB sensor. In this study, we designed a new type of compact low frequency UWB sensor based on microstrip antenna technology to detect both the low frequency and high frequency band of the partial discharge signal. Experiments of offline PD testing on medium voltage (22.9kV) underground cable mention the comparative results with the traditional HFCT as a reference sensor in the laboratory. In the series of comparative tests, the calibration signal injection test provided with the conventional IEC 60270 method and high voltage injection testing are included.