• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 전기설비
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• pp.82-84
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• 2005

In a transformer, thermal stress is the most influential parameter affecting the aging behavior of insulation system. The aging behavior of insulation system in transformer is determined mainly by the thermal conditions inside the transformer. The thermal stress on the insulation system may occur from operation in a high temperature caused by overloading or local overheating. Thus, this paper investigated the condition monitoring of insulation condition in thermally accelerated aged transformer oils by in-situ sensor. The condition of aged samples was investigated by measurements of relative permittivity i.e. capacitance change by capacitive sensor. Results from the experiments are presented in this paper.

• 한국철도학회논문집
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• 제9권6호
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• pp.671-676
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• 2006

A measurement system was developed in this study. It conducts on-line testing and evaluation of tilting train express(TTX). The measurement system is installed in each train for the performance measurement during the test run. It is composed of software part, hardware part and can measure various signals such as vehicle velocity, catenary voltage, motor temperature. The software controls the hardware of the measurement system, performs the analysis and calculation of measurement data and acts as interface between users and the system hardware. The hardware is consisted of 7 DAMs(Data Acquisition Modules) and 6 monitoring modules.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 제35회 춘계학술대회
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• pp.53-62
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• 2002

Condition monitoring plays a vital role since it sustains reliable operation of industrial plants and machinery in the pursuit of economic whole life operation. In order to achieve this goal, it is needed to monitor various parameters of mechanical system such as vibration, wear, temperature and etc., and finally to diagnosis the root causes of any possible abnormal machine condition. In this work, a machine failure caused by mechanical looseness was experimentally simulated and on-line measurement of the vibration, wear and temperature were simultaneously measured. For the quantitative analyses of machine wear, several statistical parameters of the wear particle size distribution were obtained through the center moment method of the Weibull distribution function, and they were compared to vibrational characteristics. Results showed that the wear and vibrational characteristics did not reveal a strong correlation each other in a loosely supported proceeding bearing.

• 한국환경과학회지
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• 제19권11호
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• pp.1397-1405
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• 2010

Mass mortalities of cultivated organisms have occurred frequently in Korean coastal waters causing enormous losses to cultivating industry. The preventive measures require continuous observation of farm environment and real-time provision of data. However, line hanging aquaculture farm are generally located far from monitoring buoys and has limitations on installation of heavy equipments. Substituting battery pack for solar panels and miniaturizing size of buoy, newly developed system can be attached to long line hanging aquaculture farm. This system could deliver measured data to users in real-time and contribute to damage mitigation and prevention from mass mortalities as well as finding their causes. The system was installed off Gijang and Yeongdeck in Korea, measuring and transmitting seawater temperature at the sea surface every 30 minutes. Short term variation of seawater temperature, less than one day, in Gijang from June to July 2009 corresponded tidal period of about 12 hours and long term variation seemed to be caused by cold water southeast coast of Korea, particularly northeast of Gijang. Seawater temperature differences between Gijang station and the other station that is about 500 m away from Gijang station were $1^{\circ}C$ on average. This fact indicates that it is need to be pay attention to use substitute data even if it is close to the station. Daily range of seawater temperature, one of crucial information to aquaculture, can be obtained from this system because temperature were measured every 30 minutes. Averages of daily range of temperature off Gijang and Yeongdeok during each observation periods were about $2.9^{\circ}C$ and $4.7^{\circ}C$ respectively. Dominant period of seawater temperature variation off Yeongdeok was one day with the lowest peak at 5 a.m. and the highest one at 5 p.m. generally, resulting from solar radiation.

• Journal of Power Electronics
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• 제17권3호
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• pp.695-703
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• 2017

In order to satisfy the urgent requirements for the overheating protection of induction motors, an approach that can be used to identify motor temperature has been proposed based on the rotor slots harmonic (RSH) in this paper. One method to accomplish this is to improve the calculation efficiency of the RSH by predicting the stator winding distribution harmonic order by analyzing the harmonics spectrum. Another approach is to increase the identification accuracy of the RSH by suppressing the influence of voltage flashes or current surges during temperature estimation based on model predictive control (MPC). First, an analytical expression of the stator inductance is extracted from a steady-state positive sequence motor equivalent circuit model developed from the rotor flux field orientation. Then a procedure that applies MPC for reducing the identification error of the rotor temperature caused by voltage sag or swell of the power system is given. Due to this work, the efficiency and accuracy of the RSH have been significantly improved and validated our experiments. This work can serves as a reference for the on-line temperature monitoring and overheating protection of an induction motor.

• Nuclear Engineering and Technology
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• 제45권7호
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• pp.941-950
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• 2013

The Korean Nuclear-Hydrogen Technology Development (NHTD) Plan will be performing irradiation testing of coated particle fuel at HANARO to support the development of VHTR in Korea. This testing will be carried out to demonstrate and qualify TRISO-coated particle fuel for use in VHTR. The testing will be irradiated in an inert gas atmosphere without on-line temperature monitoring and control combined with on-line fission product monitoring of the sweep gas. The irradiation device contains two test rods, one has nine fuel compacts and the other five compacts and eight graphite specimens. Each compact contains about 260 TRISO-coated particles. The irradiation device is being loaded and irradiated into the OR5 hole of the in HANARO core from August 2013. The device will be operated for about 150 effective full-power days at a peak temperature of about $1030^{\circ}C$ in BOC (Beginning of Cycle) during irradiation testing. After a peak burn-up of about 4 atomic percentage and a peak fast neutron fluence of about $1.7{\times}10^{21}\;n/cm^2$, PIE (Post-Irradiation Examination) of the irradiated coated particle fuel will be performed at IMEF (Irradiated Material Examination Facility). This paper reviews the design of test rod and irradiation device for coated particle fuel, and discusses the technical results for irradiation testing at HANARO.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.150.1-150
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• 2001

This paper introduces a real time inspecting and monitoring system by using wireless communication and image processing technique. The communication system is developed by using 80c196kc microprocessor and it has data acquisition function for several kinds of sensors such as pluviometer, temperature, tension meter, elinometer and so on. The image processing method adopts Lalacian of Gaussian operator and least square method to extract line features for the captured images and uses a relaxation matching algorithm based in global structure constraint satisfaction to distinguish the matching error for those features. When the algorithm is processed, motion parameters of displacement area and its direction are computed. Once movement is recognized ...

• Corrosion Science and Technology
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• 제9권2호
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• pp.57-66
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• 2010

Since nuclear power plants are being operated under high temperature and high pressure, on-line monitoring technique to detect corrosion could be more effective than off-line method in shut-off period. In this operating condition, electrochemical noise method may be suitable to monitor the corrosion. This paper aims the analysis on the relation between the cracking and electrochemical noise signal of Alloy 600 under U-bending. When electrochemical noise monitoring technique was used during SCC test, it was judge to be obvious that if cracks generate, its generation can be detected by electrochemical current noise. Cracking-related noise was defined as the noise showing 5~10 times greater than the average value of background noise bands. On the base of crack noise, crack initiation time was determined. From SCC test and electrochemical noise monitoring in $25^{\circ}C$, 0.1 M $Na_2S_4O_6$ solution (Reverse U-Bended Alloy 600 SE+), average crack initiation time was obtained as 9,046 seconds and from its initiation time, it could be defined that net crack propagation rate is the crack length divided by ${\Delta}T$(= total test period - crack initiation time). Therefore, average net crack propagation rate was obtained to be $1.18{\times}10^{-9}\;m/s$.

• 한국해안·해양공학회논문집
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• 제22권3호
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• pp.171-180
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• 2010

일본 미카와만의 연안 모니터링 부이에서 연속 관측한 수온 및 염분자료를 이용하여 성층의 시간적인 변화 양상을 분석하였다. 분석결과 우선 성층은 뚜렷하고 우세한 1년 주기의 변화 양상을 보이고 있으며, 표층과 저층의 밀도차이로 정의되는 성층강도는 강도가 증가할수록 발생빈도는 기하급수적으로 감소하는 양상을 보이는 것으로 파악되었다. 한편 성층강도의 발생빈도 분포는 정규분포 형태와는 다른 대수 정규분포 또는 지수분포 형태에 보다 근접한 것으로 파악되었다. 수온과 염분의 분산도 분석결과, 저층은 직선 형태의 변화 양상을 보이고 있으나 표층은 곡선 또는 고리(loop) 형태의 변화양상을 보이고 있는 것으로 파악되었다. 한편 성층강도 추정오차를 분석한 결과, 월 4회 관측빈도의 자료를 이용한 오차범위는 본 연구에서와 같이 관측부이의 1일 연속자료를 이용한 오차범위보다 4.45배 이상 증가하는 것으로 파악되었다.

• Ecology and Resilient Infrastructure
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• 제7권3호
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• pp.181-188
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• 2020

본 연구에서는 광섬유를 활용한 온도분포 센싱 방법을 실규모 제방 실험에 적용하여, 제방의 사면과 제체 내부의 변화를 모니터링하는 광역형 제방 모니터링 기술의 적용성을 검토하였다. 실규모 제방에 광섬유를 매립하고 저류지의 수위 변화에 따른 제체 내부의 시간적, 공간적 온도 변화를 측정하였다. 저류지 수위가 증가함에 따라 제방 사면의 온도는 감소하였으며, 침투가 진행되면서는 온도 변화가 나타나는 공간적 위치의 변화가 감지되었다. 제방 침투로 인한 온도 변화는 침투 경과 시간에 따라 차이가 나타났고, 침윤선으로 추정되는 변화를 관찰할 수 있었다. 본 연구를 통해 제방 내부의 온도 변화에 대한 정보는 제방 내부의 상태 변화를 판단하고 상대적으로 취약하다고 판정되는 지점에 대한 정보로 해석될 수 있음을 증명하였다.