• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2431-2438
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• 2013

The paper presents a procedure for how to development and theoretical review on Dissolved Gas Analyzer. the information of abnormal thermal stress on electrical power equipment by testing the gas is validated to easy by the gas analyzer presented in the paper. the analyzed information is used to evaluate the stability of electrical power equipment. the existing and selling DGA(dissolved gas analyzer) is so expensive and vast that all DGA product comes from foreign country. The objective of the paper is to prove that PAS(photoacoustic spectroscopy) based on a compact portable DGA solve the fixed type of DGA in order to eliminate the occurring issue directly or indirectly. the proposed DGA is easy to handle, and this can also analysis in real time for testing electrical power equipment. By applying the proposed portable, DGA be utilized in the currently electrical power equipment that are being implemented to reduce cycle of analysis of dissolved gas, it can contribute to improving safety by providing the agility of the evaluation of degradation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.3
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• pp.114-119
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• 2011

Large Power transformer is a complex and critical component of power plant and consists of cellulosic paper, insulation oil, core, coil etc. Insulation materials of transformer and related equipment break down to liberate dissolved gas due to corona, partial discharge, pyrolysis or thermal decomposition. The dissolved gas kinds can be related to the type of electrical faults, and the rate of gas generation can indicate the severity of the fault. The identities of gases being generated are using very useful to decide the condition of transformation status. Therefore dissolved gas analysis is one of the best condition monitoring methods for power transformer. Also, on-line multi-gas analyzer has been developed and installed to monitor the condition of critical transformers. Rogers method, IEC method, key gas method and Duval Triangle method are used to failure diagnosis typically, and those methods are using the ratio or kinds of dissolved gas to evaluate the condition of transformer. This paper analyzes the reliability of transformer diagnostic methods considering actual dissolved gas concentration. Fault diagnosis is performed based on the dissolved gas of five transformers which experienced various fault respectively in the field, and the diagnosis result is compared with the actual off-line fault analysis. In this comparison result, Diagnostic methods using dissolved gas ratio like Rogers method, IEC method are sometimes fall outside the ratio code and no diagnosis but Duval triangle method and Key gas method is correct comparatively.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.819-822
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• 2001

In this study a fiber optic biosensor has been developed to on-line monitor the concentrations of oxygen and glucose. The oxygen concentrations in solution and gas phase monitored by the fiber optic sensor has been compared with those by a dissolved oxygen electrode and an IR-type $O_2$ analyzer. The fiber optic glucose sensor has been made by immobilizing glucose oxidase on the tip of the optic fiber and used to on-line monitor the concentration of glucose in a fermentation process.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2091-2092
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• 2011

해마다 KEPCO에서는 구매하는 배전기자재 구매비용중 변압기가 차지하는 비중은 1800여억원('10년)으로 최대 구매비중을 차지하고 있으며(32%) 계속 증가하고 있는 추세이다. 따라서 배전용 변압기의 효율적 관리 및 수명연장에 대해서는 다양한 연구 및 관리방안을 운영하고 있으며, 그중 유중 가스분석을 통해 변압기의 열화상태를 진단하는 방법을 현장에서 가장 신뢰성있는 방법으로 운영하고 있다. KEPCO에서는 변전용 대형변압기 및 배전용 지상변압기에 대하여 절연유를 채취하여 가스분석을 하고 자체기준에 의거 열화판정 기준으로 적용하고 있다. 하지만 이러한 방식이 절연유 채취후 운반과정에서의 신뢰성, 분석시간 장기간 소요, 분석비용 등 여러 가지 현안문제를 안고 있는 실정이다. 본 연구에서는 이러한 문제점을 보완할 수 있는 변압기 진단방법을 제시하고, 새로운 방식에 대한 검증을 통해 현장 적용 가능성을 검토해 보고자 한다.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.701-706
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• 2008

Nano-sized nickel powders were prepared by evaporating the bulk nickel metarial using transferred arc thermal plasma. Nitrogen gases are easily dissociated to atomic nitrogen in thermal plasma and they are quickly dissolved in molten nickel. Super-saturated atomic nitrogen in molten nickel is recombined to nitrogen gas because of the relatively low temperature of nickel surface. Generally, the recombine reaction of atomic nitrogen is exothermic, so bulk nickel is quickly evaporated to nickel vapor due to the thermal energy of recombine reaction. The particle size of nickel powder was controlled by $N_2$ used as the diluting gas. It was observed that as the diluting gas flow rate was increase, the particle size was decreased and the particle size distribution was narrowed. The average particle size at 250 l/min of the diluting gas was 202 nm analyzed by means of the particle size analyzer (PSA).

• Journal of the Korean earth science society
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• v.34 no.7
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• pp.681-692
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• 2013

We aimed to evaluate the effectiveness of the Giggenbach bottle method and develop the related pretreatment and analytical methods using artificial fumarolic gases. The artificial fumarolic gases were generated by mixing $CO_2$, CO, $H_2S$, $SO_2$, $H_2$, and $CH_4$ gas streams with a $N_2$ stream sparged through an acidic medium containing HCl and HF, with their compositions varied by adjusting the gas flow rates. The resultant fumarolic gases were collected into an evacuated bottle partially filled with a NaOH absorption solution. While non-condensible gases such as CO, $H_2S$, and $CH_4$ accumulated in the headspace of the bottle, acidic components including $CO_2$, $SO_2$, HCl, and HF that were dissolved into the alkaline solution. Like other acidic components, $H_2S$ also dissolved into the solution, but it reacted with dissolved $Cd^{2+}$ to precipitate as CdS when $Cd(CH_3COO)_2$ was added. The non-condensible gases were analyzed on a gas chromatography. Then, CdS precipitates were separated from the alkaline solution by filtration, and they were pretreated with $H_2O_2$ to oxidize CdS-bound sulfide into sulfate. In addition, a portion of the solution was also pretreated with $H_2O_2$ to oxidize sulfite to sulfate. Following the pretreatment, the resultant samples were analyzed for $SO_4^{2-}$, $Cl^-$ and $F^-$ on an ion chromatography. In the meanwhile, dissolved $CO_2$ was analyzed on a total organic carbon-inorganic carbon analyzer without such pretreatment. According to our experimental results, the measured concentrations of the fumarolic gases were shown to be proportional to the gas flow rates, indicating that the Giggenbach bottle method is adequate for monitoring volcanic gas. The pretreatment and analytical methods employed in this study may also enhance the accuracy and reproducibility of the Giggenbach bottle method.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1694-1697
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• 2002

KEPCO is planing to adopt a preventive diagnostic system to obtain the reliability of transformer and GIS in 765kV substation. KEPRI has developed the preventive diagnostic system for 765kV substation since 1997. We used various sensors and fault detecting devices such as a dissolved gas analyzer in oil, a ultrasonic detector and LA leakage current detector, etc., and carried out adaptation tests at the both a laboratory and a site. We developed a data acquisition system, a communication control unit and a server system as well. Furthermore, monitoring program and diagnostic expert system were also developed. This paper describes the preventive diagnostic system for 765kV Sin-Ga-Pyong and Sin-Tae-Baek substations which will be operated from 2004.

• Elastomers and Composites
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• v.30 no.3
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• pp.185-194
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• 1995

Membrane process has been employed to separate a specific substance from gas or liquid mixture, and treat wastewater. This is due to the fact that the substance of mixture can be permeated and separated selectively by membrane. Since Initial equipment and operation costs are not expensive, membrane process has been adopted in various fields such as petroleum Industry, chemistry, polymer, electronics, foods, biochemical industry and wastewater treatment. In this study, $CaCO_3$ particles impregnated in silicone rubber network were extracted by using supercritical carbon dioxide and pore distribution of silicone $rubber-CaCO_3$ was investigated with varying amount of extract. Silicone rubber has excellent mechanical properties such as heat-resistance, cold-resistance etc. and $CaCO_3$ has microporous structure. It is possible to make silicone $rubber-CaCO_3$ composite sheets via work-intensive kneading processes. In so doing $CaCO_3$ particles become distributed and impregnated in silicone rubber network. Supercritical carbon dioxide diffuse through composite sample, then sample is swollen. $CaCO_3$ in silicone rubber network Is dissolved in supercritical carbon dioxide, and its sites become pores. Pore distribution, pore shape and surface area are observed by SEM(scanning electron microscope) micrograph and BET surface area analyzer examination respectively. Pore characteristics of membrane suggest the possibilities that the membrane can be used for process of mixture separation and wastewater treatment.

• The Korean Journal of Physiology
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• v.20 no.1
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• pp.53-63
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• 1986

Carbon monoxide(CO) poisoning has been one of the major environmental problems because of the tissue hypoxia, especially brain tissue hypoxia, due to the great affinity of CO with hemoglobin. Inhalation of the pure oxygen$(0_2)$ under the high atmospheric pressure has been considered as the best treatment of CO poisoning by the supply of $0_2$ to hypoxic tissues with dissolved from in plasma and also by the rapid elimination of CO from the carboxyhemoglobin(HbCO). Hydrogen peroxide $(H_2O_2)$ was rapidly decomposed to water and $0_2$ under the presence of catalase in the blood, but the intravenous administration of $H_2O_2$ is hazardous because of the formation of methemoglobin and air embolism. However, it was reported that the enema of $H_2O_2$ solution below 0.75% could be continuously supplied $0_2$ to hypoxic tissues without the hazards mentioned above. This study was performed to evaluate the effect of $H_2O_2$ enema on the elimination of CO from the HbCO in the recovery of the acute CO poisoning. Rabbits weighting about 2.0 kg were exposed to If CO gas mixture with room air for 30 minutes. After the acute CO poisoning, 30 rabbits were divided into three groups relating to the recovery period. The first group T·as exposed to the room air and the second group w·as inhalated with 100% $0_2$ under 1 atmospheric pressure. The third group was administered 10 ml of 0.5H $H_2O_2$ solution per kg weight by enema immediately after CO poisoning and exposed to the room air during the recovery period. The arterial blood was sampled before and after CO poisoning ana in 15, 30, 60 and 90 minutes of the recovery period. The blood pH, $Pco_2\;and\;Po_2$ were measured anaerobically with a Blood Gas Analyzer and the saturation percentage of HbCO was measured by the Spectrophotometric method. The effect of $H_2O_2$ enema on the recovery from the acute CO poisoning was observed and compared with the room air group and the 100% $0_2$ inhalation group. The results obtained from the experiment are as follows: The pH of arterial blood was significantly decreased after CO poisoning and until the first 15 minutes of the recovery period in all groups. Thereafter, it was slowly increased to the level of the before CO poisoning, but the recovery of pH of the $H_2O_2$ enema group was more delayed than that of the other groups during the recovery period. $Paco_2$ was significantly decreased after CO poisoning in all groups. Boring the recovery Period, $Paco_2$ of the room air group was completely recovered to the level of the before CO Poisoning, but that of the 100% $O_2$ inhalation group and the $H_2O_2$ enema group was not recovered until the 90 minutes of the recovery period. $Paco_2$ was slightly decreased after CO poisoning. During the recovery Period, it was markedly increased in the first 15 minutes and maintained the level above that before CO Poisoning in all groups. Furthermore $Paco_2$ of the $H_2O_2$ enema group was 102 to 107 mmHg and it was about 10 mmHg higher than that of the room air group during the recovery period. The saturation percentage of HbCO was increased up to the range of 54 to 72 percents after CO poisoning and in general it was generally diminished during the recovery period. However in the $H_2O_2$ enema group the diminution of the saturation percentage of HbCO was generally faster than that of the 100% $O_2$ inhalation group and the room air group, and its diminution in the 100% $O_2$ inhalation group was also slightly faster than that of the room air group at the relatively later time of the recovery period. In conclusion, the enema of 0.5% $H_2O_2$ solution is seems to facilitate the elimination of CO from the HbCO in the blood and increase $Paco_2$ simultaneously during the recovery period of the acute CO poisoning.