• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.207-210
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• 2004

In oil-filled equipment such as transformers, partial discharge or local overheating will make insulating material(oil, kraft paper, proclain and wood) be stressed and generate many sort of gases($CO,\;CO_2,\;H_2,\;C_2H_4$) which are dissolved in transformer oil. The ratio of this gas can make diagnostic tecchniques of the lifetime of transfomer so, it is important to monitoring $H_2$ gas continuously. This paper developes a system of detecting about $H_2$ gas by using $H_2$ gas sensor, and we describe operation and performance of this system

• Tribology and Lubricants
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• 제30권3호
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• pp.156-167
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• 2014

This paper presents the test results of small dipstick-gage-type engine-oil-deterioration-detection sensor. The measured sensor signal characteristics for the capacitance and temperature are analyzed. The engine oil deterioration condition correlates with the electrical property of the dielectric constant that comprised with physical properties such as TAN (Total Acid Number), TBN (Total Base Number) and viscosity. Several problems encontered during the test of the sensor system are improved. The results of vehicle tests show that the capacitance signal is stable after the engine stops. Therefore, the sensor should start measuring the parameters for monitoring the engine oil condition after the engine stops. The engine is considered to be in a stopped state if the difference between the maximum and minimum values of the oil capacitance measured every 1 min is below 0.02 pF. The key test results in this paper will help in the development of an engine oil change warning algorithm.

• 한국대기환경학회지
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• 제34권3호
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• pp.393-405
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• 2018

Volatile organic compounds (VOCs) are representative air pollutants due to their detrimental effects on human health and their role in formation of secondary organic aerosols. Assessments and monitoring programs of VOCs using periodic grab sampling like Tedlar bags, canisters, and sorbent traps provide limited information, often with delay times of days or weeks. Selected ion flow tube mass spectrometry (SIFT-MS) is an emerging analytical technique for the real-time quantification of VOCs in air. It relies on chemical ionization of the VOCs molecules in air introduced into helium carrier gas using $H_3O^+$, $NO^+$, and $O_2{^+}$ precursor ions. Real-time monitoring method of 60 VOCs in the ambient air was developed using TO-15 standard gas mixture. Calibration curves, method detection limit, and quantitation reproducibility of the target compounds were tested. Dynamic dilution system was used to dilute standard gas from 0.174 ppbv to 100 ppbv, where calibration curves showed good linearity with $r^2$> 0.95 in all target analytes. Limit of detection (LOD) all compounds were sub ppbv, and some halogenated compounds showed pptv levels. Seven consecutive analyses of target compounds showed good repeatability with relative standard deviation of less than 10%. One day monitoring of VOCs in ambient air was conducted in Geoje. Average concentration of target VOCs in Geoje were relatively lower than other regions, among which formaldehyde showed the highest concentration ($15.4{\pm}5.78ppbv$). SIFT-MS provided good temporal resolution data (1 data per 3.2 minute), which can be used for identifying ephemeral short-term event. It is expected that SIFT-MS will be a versatile monitoring platform for VOCs in ambient air.

• Tribology and Lubricants
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• 제25권1호
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• pp.56-60
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• 2009

A journal bearing is used in a hydrodynamic lubrication state, but it becomes a boundary lubrication state that asperity of a contact part touch each other when pressure is too high and an enough oil film is not formed by viscosity change due to lubricating oil temperature. At this time, abrasion due to contact between a journal and a bearing is unavoidable, and scuffing damage that the journal adheres to the bearing occurs if the process is repeated. Damage of the journal bearing is an important problem because it gives huge damage to a machine and can generate large accidents such as economic loss and human life damage. In this study, method for using the pull-up resistor concept was introduced as the monitoring technology. This monitoring system is important to enhance reliability of the engine.

• Tribology and Lubricants
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• 제35권3호
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• pp.151-157
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• 2019

Insulated oil degradation produces charged by-products, such as acids and hydro-peroxides, which tend to reduce the insulating properties of the oil. In this study, UV-vis spectroscopy measurement technology is developed and experimentally compared with other measurement methods, such as the titration method and IR spectroscopy, to validate its ability to monitor the degradation of electrical insulating paper. The degradation characteristics of the insulating paper are appropriately represented through various types of measurement methods, such as the Tan (delta) method, $CO_2$ gas production measurement, the titration method, and IR spectroscopy. The results are demonstrated to be well comparable to a change in the fluorescence emission ratio (FER), which is defined as the shift in fluorescence intensity in the measured wavelength range, and also to the chromatic ratio, which is defined as a color shift to longer wavelength ranges. The results also show that, by using UV-vis spectroscopy, it is possible to detect the degradation of the insulating paper. This study suggests that UV-vis spectroscopy can be applied as an alternative to high-performance liquid chromatography, which is the internationally recognized measurement technology for cellulose paper degradation. The FER detector is also verified to be useful as an effective condition-monitoring device for power transformers.

• 한국축산식품학회지
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• 제36권5호
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• pp.612-616
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• 2016

This study was conducted to investigate the condition of frying oil used for frying chicken nuggets in a deep fryer. The acidification of the frying oils used, soybean oil (SB), canola oil (CA), palm oil (PA), and lard (LA), were determined as peroxide value, acid value, and fatty acid composition, after chicken nuggets were fried in them for 101 times. The acid value and peroxide value obtained were 5.14 mg KOH/g and 66.03 meq/kg in SB, 4.47 mg KOH/g and 71.04 meq/kg in CA, 2.66 mg KOH/g and 15.48 meq/kg in PA, and 5.37 mg KOH/g and 62.92 meq/kg in LA, respectively. The ranges of the major fatty acid contents were palmitic acid, 8.91-45.84%; oleic acid, 34.74-58.68%; linoleic acid, 10.32-18.65%; and stearic acid, 2.28-10.86%.Used frying oils for food except animal products have a legal limit for the freshness standard, set by the Food Codex regulations (AV<2.5, POV<50). Therefore, this study could help develop a freshness standard for frying oils used for animal products such as chicken nuggets. Based on the quality limits associated with food regulations stated, we suggested that the estimated frying times before acceptable freshness was exceeded were 41 for SB, 38 for LA, 53 for CA, and 109 for PA. This data may be useful in determining food quality regulations for frying oil used for animal products.

• Tribology and Lubricants
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• 제15권2호
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• pp.131-140
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• 1999

This study dealt with some problems occurred in spectrometric oil analysis that has been popularly used for a machine condition monitoring in various fields of industry. One of the problems is that spectrometric technique could not analyze contaminants of large particle (larger than 10 $\mu\textrm{m}$) in lubricating oils. This limitation caused a serious problem in analyzing lubricated machine conditions since wear debris of large size represents better critical machine conditions. In this work, this problem was found to be solved by using a filtration method prior to spectrometric analysis. Another problem could be that spectrometric analysis is incapable of identifying contaminants. This nay mislead the result seriously in practice. This problem was surveyed by analyzing both various types of industrial lubricants and laboratory simulation tests, and the solutions to the problem were suggested in this work.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 추계학술발표회
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• pp.151-151
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• 2017

• 대한전기학회논문지:전력기술부문A
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• 제50권3호
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• pp.131-139
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• 2001

As increasing the accident of Distribution Transformer (DT), we need to manage them efficiently. In this paper, we discusses with the possibility of the diagnostic technique for distribution transformer using relative ageing rate calculation in this paper. The relative ageing rate of the DT could be calculated from the measured top oil temperature, ambient temperature and load current. In order on apply the proposed diagnostic technique we developed an on line Monitoring and Diagnostic System (MDS) which has hardware and software part. Diagnostic device is developed to measure the state information of DT and to send them with R/F(radio frequency) communication. Host computer monitors and saves the receive data. The database is constructed from the data of distributed DT and it is used for estimating loss-of-life in the MDS.

• The Journal of Asian Finance, Economics and Business
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• 제7권6호
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• pp.145-155
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• 2020

This study analyzes the degree of competition in the oil refinery market in Korea, which is considered an oligopoly market. The price of gasoline and diesel and the quantity of supply are used to identify the market competition. We also analyze whether the oil tax reduction policy has affected market competition. The competitiveness of the market was examined using monthly data from 2008 to 2019. Bresnahan-Lau method was employed to estimate the degree of competition in the oil refinery market, which is frequently used in the industrial studies. The analysis shows that the gasoline and diesel markets seem close to a perfect competitive market. Also, the tax cut has weakened market competition. In other words, the monopolistic power has increased in the market, so consumers have not benefit from the price cuts as much as tax cuts. Although the oil refinery market where four major companies are competing, the government's monitoring and price disclosure system help the market to be highly competitive as much as a perfect competition market. The tax cut, in the high oil price era, has a negative effect on the competition because of an information asymmetry about the price-setting process between suppliers and consumers.