• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.900-904
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• 2009

The measurement of contact wire uplift in electric railway is one of the most test method to accept the maximum permitted speed of new vehicles or pantographs. The contact wire uplift can be measured for shot periods when pantograph is running in monitoring station. This paper describes the development of two different methods for contact uplift measurement using vision-based system and wireless online monitoring system. Our vision-based system employs a high-speed CMOS (Complementary Metal Oxide Semiconductor) camera with gigabit ethernet LAN. The development of a real-time remote monitoring system that acquires data from any kind of sensor to be transmitted by wireless communication from overhead line and structure at 25 kV to a computer in catenary system. The proposed two kind of different measurement systems to evaluation for dynamic uplift of overhead contact wire shows promising on-field applications for high speed train such as Korea Tilting Train (TTX) and Korea Train eXpress (KTX).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.108-109
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• 2008

Forest Fire can cause a serious damage to overhead conductors. Therefore, the detailed investigation for the changes of mechanical and electrical properties of damaged conductors should be carried out to understand the effect of forest fires on conductors. This is very much important to maintain transmission line safely. Especially, this paper describes the changes of mechanical and electrical properties of flame exposed conductor. The detailed will be given in the text.

• 한국전기전자재료학회논문지
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• 제20권12호
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• pp.1105-1111
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• 2007

Because forest fire can give a serious damage to overhead conductors, the thorough understanding about aging behavior of burned conductor is very important in maintaining the transmission line safely. Therefore, a systematic investigation was carried out by heating method. As the heating temperature increases, drastic change of tensile strength of Al wire due to the softening of Al wire occurred. When Al wire is exposed to the flame(about $800\;^{\circ}C$) during only 13 seconds, the remained tensile strength of Al wire showed under 90 %. The detailed results will be given in the text.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.152-157
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• 2005

Recently, higher speeds have been promoted in old overhead-lines. For high-speed operation in electric railways, increasing contact loss of the pantograph is one of the most important subjects. The contact loss causes power interruption and increases wear of contact strips and contact wires. In order to investigate the causes of contact loss and to work out effective improvement methods, theoretical analyses, experiments have been carried out. First of all, the wave propagating velocity (phase velocity) and characteristics of contact wire are one of the important indices for the current collecting performance. In this paper, mathematical formula arc derived for the prediction of the traveling wave velocity. The measured values in the experiment agree well with the theoretical predictions.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.523-524
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• 2007

Forest fire can give a serious damage to overhead conductors. Therefore, the definite understanding about aging behavior of burned conductor is very important in maintaining the transmission line safely. It is sure that the temperature of conductor itself will be affected by the distance apart from flame. From this point of a view, we monitored the conductor's temperature with distance from flame. As a result, the conductor's temperature decreased as the flame goes away from the conductor gradually. The temperature of conductor was reached up to 55~65% level of its atmospheric temperature. The detailed results will be presented in the text.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.534-535
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• 2007

Because forest fire can give a serious damage to overhead conductors, the thorough understanding about aging behavior of burned conductor is very important in maintaining the transmission line safely. Therefore, a systematic investigation was carried out by heating method. As the heating temperature increases, drastic change of tensile strength of Al wire due to the softening of Al wire occurred. When Al wire is exposed to the flame(about $800^{\circ}C$) during only 13 seconds, the remained tensile strength of Al wire showed under 90%. The detailed results will be given in the text.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2718-2731
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• 2019

Conjunctive keyword search encryption is an important technique for protecting sensitive data that is outsourced to cloud servers. However, the process of searching outsourced data may facilitate the leakage of sensitive data. Thus, an efficient data search approach with high security is critical. To solve this problem, an efficient conjunctive keyword search scheme based on ciphertext-policy attribute-based encryption is proposed for cloud storage environment. This paper proposes an efficient mechanism for removing the secure channel and resisting off-line keyword-guessing attacks. The storage overhead and the computational complexity are regardless of the number of keywords. This scheme is proved adaptively secure based on the decisional bilinear Diffie-Hellman assumption in the standard model. Finally, the results of theoretical analysis and experimental simulation show that the proposed scheme has advantages in security, storage overhead and efficiency, and it is more suitable for practical applications.

• 한국전자통신학회논문지
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• 제16권4호
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• pp.577-584
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• 2021

전기에너지는 현사회에서 가장 필수적인 요소이고 우리 기술사회의 중요한 근간이다. 새로운 전력 인프라를 설계하는데 있어서 우리의 문화적인 고려사항과 공동체 환경의 필수적인 요소처럼 개발하는 방향을 심리적인 관점에서 검토하는 것이 중요하다. 새로운 고압송전선로 건설은 사회적인 반대 때문에 정부의 공공정책에 대한 갈등주제가 되고 있다. 공동체 구성원들은 이 송전선로가 그들의 건강과 안전에 영향을 끼치는 이유로 인해서 자기들의 생활에 어떤 영향을 줄 것인지에 관해서 걱정하고 있는 것이다. 경관과 시각적인 효과는 지역사회에서 가장 손쉽게 인지하는 것 중 하나이다. 새로운 경관의 3차원 컴퓨터 모사는 지역사회에 대하여 최소한 예상되는 관측성을 갖는 전력선 경로선택에 맞추어진 실생활의 사진이다. 본 논문은 송전선로 영역의 계획, 조사, 기본 및 상세경로, 경로구축을 위해서 ArcGIS를 사용하였다. 그리고 송전선로 영역의 데이터베이스를 사용하여 자연경관, 생활환경, 안전성과 고도에 대한 지도를 제시하였으며, 이 연구를 통하여 송전영역 모델을 개발하였다. 송전선로 지역에서 최소한의 가시권을 갖도록 컴퓨터로 모사하여 제안된 경관은 지역사회의 반발을 줄일 수 있으며, 새로운 전력선의 공사를 촉진할 수 있다.

• Structural Engineering and Mechanics
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• 제78권1호
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• pp.87-102
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• 2021

Long span cross-rope suspension structure is an innovative structural system evolved from typical Cross-Rope Suspension (CRS) guyed tower, a type of supporting system with short span suspension cable supporting overhead power transmission lines. In mountainous areas, the span length of suspension cable was designed to be extended to hundreds or over one thousand meters, which is applicable for crossing deep valleys. Vortex Induced Vibration (VIV) of overhead power transmission lines was considered to be one of the major factors of its fatigue and service life. In this paper, VIV and its controlling by Stockbridge damper for long span CRS was discussed. Firstly, energy balance method and finite element method for assessing VIV of CRS were presented. An approach of establishing FE model of long span CRS structure with dampers was introduced. The effect of Stockbridge damper for overall vibration of CRS was compared in both theoretical and numerical approaches. Results indicated that vibration characteristics of conductor in long span CRS compared with traditional tower-line system. Secondly, analysis on long span CRS including Stockbridge damper showed additional dampers installed were essential for controlling maximum dynamic bending stresses of conductors at both ends. Moreover, factors, including configuration and mass of Stockbridge damper, span length of suspension cable and conductor and number of spans of conductor, were assessed for further discussion on VIV controlling of long span CRS.

• 조명전기설비학회논문지
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• 제22권4호
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• pp.139-146
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• 2008

가공송전선 도체는 장기간 동안 다양한 환경조건에 노출되어 있으므로 공기오염원이나 열적 이력에 의하여 서서히 열화된다. 노화도체는 전력시스템의 신뢰성과 공중 안전을 감소시키다. 따라서 운용 중인 노화도체의 진단은 적정한 용량으로 전력을 안전하게 공급하거나 노화도체의 교체 또는 새로운 선로의 건설이라는 관점에서 매우 중요한 관심사가 되었다. 본 논문에서는 이도를 측정하여 노화도체의 교체수명을 진단하고 잔존수명을 추정하는 새로운 방법을 제안한다. 도체온도, 도체전류 및 장력 사이의 관계를 해석함으로써 이도가 노화도체의 기계적 인장손실을 정확하게 나타낼 수 있다는 것을 확인하였다. 몇 가지 수치해석결과를 토대로 제안된 방법이 가공도체의 교체수명이나 잔존수명을 진단하는데 효과적으로 사용될 수 있음을 보였다.