• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.527-528
• /
• 2007

A field-oriented UHF system for on-line PD monitoring of transformers is designed, which has been installed inside the oil tank of a 220kV transformer in a substation. This system has successfully captured long intermittent discharge signals that hadn't been detected through conventional techniques, and solved the problem successfully. The results demonstrate that UHF technique has great advantages for on-line PD monitoring of transformers. By adopting the peak detection technique, it becomes easy and effective for the transplantation of the phase-resolved pattern recognition technique from conventional method to UHF method, and then to realize continuous on-line monitoring, source characterization and trending analysis.

• KSBB Journal
• /
• 제17권4호
• /
• pp.339-344
• /
• 2002

Flow injection analysis technique for monitoring of xylitol concentrations in biological processes has been developed using xylitol oxidase (XYO) immobilized on VA-Epoxy Biosynth carrier. The immobilized XYO cartridge has been integrated into a FIA system with an oxygen electrode and systematically investigated with regards to the factors which can affect the activity of the immobilized XYO, such as pH, temperature, salt concentration etc. The activity of the immobilized XYO increased with the temperature ($19.0 - 29.0^{circ}C$) and sample injection volume ($75-250\muL$) and molarity of potassium phosphate buffer (0.1-1 M), but it reached the highest value at pH 8.5. The XYO-FIA system has been also applied for on-line monitoring of xylitol concentrations in a reactor and showed good operational stability and agreement with off-line data measured with HPLC.

• Journal of Radiation Protection and Research
• /
• 제19권2호
• /
• pp.147-156
• /
• 1994

환경감마선량 변동을 감시하기 위해 한국원자력연구소 부지 주변에 온라인 감마선량 감시망을 구성하였다. 모니터링 포스트에 설치된 전리함 검출기에 의해 측정된 자료는 무선전송 방식으로 중앙동제소에 전송되어 실시간으로 감시된다. 무선전송 방식은 자료의 전송, 처리 및 저장에 신뢰도가 높고 경제적이었다. 감시시스템은 급격한 선량증가시 조기경보체제와 연결할 수 있게 하였다.

• 조명전기설비학회논문지
• /
• 제21권5호
• /
• pp.75-81
• /
• 2007

본 논문에서는 전기안전에 대한 부가서비스 같은 저전압 전기설비의 온라인 감시시스템 구축을 위한 국내외 실태조사를 수행하였다. 일본은 미래 정보화 사회를 위해 IT 기본법에 근거한 온라인 전기설비 감시시스템 서비스를 실시하고 있으며, 전기안전뿐만 아니라 지진이나 방범등의 부가서비스를 실시하고 있었다. 미국 및 유럽에서는 전력선 통신을 사용하여, 온라인 감시 및 빌딩군 관리 서비스를 실시하고 있었다. 국내에서도 전기안전과 관련하여 디지털 수배전반 등을 통해 누설전류 측정, 부하관리 등에 대한 서비스를 일부 기업에서 서비스를 실시하고 있었다. 실태조사를 통해, 국내에서도 시장 활성화를 위한 법, 제도적 개선이 필요할 것으로 판단된다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 A
• /
• pp.193-195
• /
• 2003

This paper presents an approach to estimate the power transmission line parameter by phasor measurement units(PMUs), which are synchronized to 1 pps signal of GPS. Existing approaches to estimate power transmission line parameter, are mainly off-line ones, based on faults or switching events on other neighboring lines. In this paper, to obtain static and dynamic properties of power transmission line parameter in service, the prototype of pmu-based Transmission Line Parameter Monitoring System (TLPMS) is proposed. Also, an technique to estimate parameters of transmission line described as 2-port network model and the soundness of estimated parameters are addressed.

• 한국정밀공학회지
• /
• 제29권12호
• /
• pp.1313-1320
• /
• 2012

Condition monitoring of the reciprocating compressor is important task. As a traditional method, health monitoring system of refrigerator depends on decision of a skilled person based on his experience. However, the skilled person cannot monitor all the compressors completely. If a sampled compressor is faulty, thousands of compressors manufactured at that place are regarded as faulty compressors. Therefore it is necessary to monitor all compressors in the production line. In the paper real time health monitoring system is developed based on high order time frequency method and artificial neural network. The system is installed in the mass production line. The result of the application has been very successful, and currently the system is working very well on the production line.

• 조명전기설비학회논문지
• /
• 제22권1호
• /
• pp.79-86
• /
• 2008

국내 및 국외에서도 마찬가지로 전기설비 안전점검에 대한 부분이 발전된 정보통신 기술(IT: Information Technology)에 접목 시켜 실시간으로 서비스를 제공하는 추세에 있다. 전기설비와 관련된 전기안전 부가서비스의 활성화를 위한 방향과 새로운 고부가 비즈니스 사업 창출을 위해서 어떤 부분에서 개선 및 추가되어야 할 부분인지에 대하여 본 논문에서 조사하였다. 따라서 전력 부가 서비스의 활성화 방향에 대하여 실시간 원격 감시 시스템의 활성화 부분과 아크 차단기 도입의 필요성 및 관련 법 부분에 대해 조사 분석하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 춘계학술대회 논문집 전기설비전문위원
• /
• pp.96-99
• /
• 2008

On-line condition monitoring is a useful tool for maintaining and extending the longevity of power transformers. An intelligent diagnostic system is desirable for operational safety and reliability. Bringing these concepts together results in a powerful support tool for engineers, reducing the volume of data to deal with, and making the data more meaningful. This paper describes how a multi-agent system for diagnosing the cause of transformer partial discharge activity was coupled with a method of UHF partial discharge monitoring, creating an on-line condition monitoring system. The challenges presented by the on-site environment are discussed, along with the implications for the complete system.

• 한국대기환경학회지
• /
• 제25권6호
• /
• pp.523-538
• /
• 2009

Recently, there has been a keen demand for real-time automatic monitoring of VOCs not only in Korea but other developed countries. We carried out this study to evaluate and to optimize the performance of a continuous automatic monitoring system for hazardous VOCs (HVOCs) in the ambient atmosphere, using an on-line GC system. The online system normally consisted of a Nafion dryer prior to a cold trap of an automatic thermal desorption apparatus and a GC system equipped with two detectors, i.e. PID and ECD. Preliminary tests conducted to check out any contamination of the system revealed an evidence of significant artifact formation of benzene, and it was found that the Nafion dryer (even brand new one) is the source of the benzene artifact. Thus, all the subsequent experiments in this study was carried out inevitably by removing the Nafion dryer. The on-line GC method was investigated with a variety of QC/QA performance criteria such as repeatability, linearity, lower detection limits, and accuracy. In order to find out the best operating condition for the on-line GC system, three different types (in terms of adsorption strength) of cold trap combinations were tested, i.e. (i) Tenax-TA and Carbopack-B combination (weak and hydrophobic); (ii) Tenax-TA, Carbopack-X and Carboxen-1000 combination (strong and hydrophilic); and (iii) Tenax-TA and Carbopack-X combination (medium and hydrophobic/hydrophilic). The USEPA TO-17 manual method was selected as a reference method to evaluate the performance of the on-line method. A series of experiments revealed that the system performance was superior to others when a cold trap packed with hydrophilic adsorbents (Tenax-TA/Carbopack-X/Carboxen-1000 combination) was used and operated at $25^{\circ}C$. However, the system with a cold trap packed with a combination of Tenax-TA and Carbopack-X is more recommended for field applications since the carboxen-1000 adsorbent is too sensitive to water vapor, and hence the performance of the system might be very unstable to humid samples or during rainy days. Furthermore, the precision and accuracy criteria of the Tenax-TA/ Carbopack-X combination were generally compatible with the triple adsorbents cold trap. The continuous automatic monitoring method is, thus, considered very useful to real-time monitoring to understand the variations of VOCs concentrations in ambient air, as it adopts much simpler procedures in sampling, analysis, and data integration steps than manual monitoring methods. However, it should be noted that there is a high possibility of benzene artifacts formation through the Nafion dryer, which is often installed to remove water vapor in air samples before being adsorbed onto the cold trap. Therefore, if a Nafion dryer is used in any studies of monitoring VOCs, the benzene contamination should be carefully examined before carrying out obtaining the data.

• 분석과학
• /
• 제15권6호
• /
• pp.496-501
• /
• 2002

Electrolyte cathode atomic discharge (ELCAD)는 용액 중에 포함된 미량 중금속을 연속 자동적으로 측정하기 위한 새로운 광학 측정기로서 플라스마에 의한 중금속들의 방출 강도를 측정하는 원자방출 분광법의 하나이다. 특히 이 방법은 검액을 전처리하지 않고 직접 분석할 수 있기 때문에 온라인 (on-line) 현장분석이 가능하다. ELCAD에서는 분위기 가스로 공기를 이용하고, 양극부분에 백금 전극을 사용하며, 음극에서는 연속적으로 전해질 시료를 주입하면서 플라스마를 형성하면서 미량의 중금속을 분석할 수 있다. 액상 글로우 방전의 기초 특성 연구로는 철의 원자 방출선 세기를 구한 다음 Einstein-Boltzmann식을 사용하여 플라스마 온도를 구한 다음 구리, 납, 철 및 니켈의 미량 분석 및 간섭 현상에 대해서 연구하였고, 검출 한계를 구하였다.