• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1896-1898
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• 2002

In this paper, to developing thermally and mechanically upgraded ones, we dismounted pole transformers used in the fields for over 13 years and conducted aged oil analysis. Also, when the cellulose and aramid papers in test cell were aging with oil at $130^{\circ}C$ for 3000 hours, with the testing period cellulose paper deteriorated more rapidly than the others. For example dielectric strength and dissipation factor of papers deteriorated with aging time. For evaluation of thermal aging characteristics, a mineral oil-immersed transformer was constructed with hybrid insulation system comprised of aramid paper and cellulose insulation. A Hybrid system has economic advantages. Cellulose materials are confined to cooler regions of the transformer winding. And aramid papers are served to insulate contact parts of hot conductors.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.03a
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• pp.23-52
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• 1994

The development if separation technology is an important research subject as is clear from its role in the Japanese government's research abd development program for basic technology for the next generation (1981~1990). Japan is poor not only in mineral resources but also in energy resources and if a sudden change occurs in oil producing facility or an accident occurs in a nuclear power plant, then energy policy must undergo changes and economic foundations may collapse. Japan has already experienced this. Although, oil prices are stable at present and Japan can import oil at low cost due to the yen appreciation, Japan needs to promote development work for any new energy crisis that may come in the future. This has been the motive for gas separation membrane development in Japan.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.23-24
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• 2015

As this study is an experiment for solving problem on the carbonation acceleration of high volume admixture concrete, the capillary pore getting filled up by saponification as cooking oil gets absorbed to the concrete surface in case of applying a cooking oil based coating agent to the concrete has been verified in the previous studies. Accordingly, this study has performed a comparative experiment on the cooking oil and the anticorrosive coating agent sold on the market while the result followed by this experiment has shown the fact of indicating similar carbonation penetration depth and porosity.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1609-1611
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• 2003

This paper presents the results on the development of capacitive sensor for the diagnosis of electrical insulating oil, widely used for power transformer. To survey the dielectric properties of the new and used mineral insulating oil, we utilized the highly precise measuring system of KRISS. And the results were used to determine the design factors of the sensor. To evaluate the operational and the hysteresis characteristics of the sensor, we constructed a test chamber, including dielectric property measuring system. Through the results we could confirm the superior characteristics of the newly developed sensor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.244-245
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• 2005

Electrical insulation is one of the most important parts in a high voltage apparatus. Traditionally mineral oils and synthetic esters have been widely used as dielectric coolants for power transformers. Recently, researchers are interested in the environmental friendly vegetable oil from environmental viewpoint. This paper reports on the synthesis and characterization of soybean based ester oils. Two different types of soybean based transformer oils, named as methyl ester and isopropyl ester were synthesized. The synthesis of these esters was achieved by transesterification reactions of soybean oil and alcohol in the presence of catalyst. The GC and NMR spectroscopic analysis of the esters have been performed. The thermal stability of the esters was determined by thermal gravimetric analysis(TGA).

• Journal of the Korean Chemical Society
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• v.41 no.5
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• pp.239-245
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• 1997

The sorption kinetic was studied to evaluate feasibility of removing PCBs from mineral oil with activated carbon. Adsorption efficiency for Aroclor 1242 which is composed of lower chlorinated PCB formulations was $\geq$ 95%, whereas the adsorption efficiency for Aroclor 1260 having higher chlorinated constituents was considerably lower with the efficiency falling to 75%. The observed difference in the adsorption efficiency is attributed to the geometry of PCBs with non-planar and coplanar structure. The concentration of coplanar PCBs is appreciably higher in Aroclor 1242. Since toxicity is primarily associated with coplanar congeners, the preferential adsorption of coplanar congeners by activated carbon accounts for the fact that toxicity reduction can be achieved through this process. The efficiency of process was assessed in terms of Toxicity Equivalence Factor (TEF).

• Journal of the Korean Society for Precision Engineering
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• v.25 no.9
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• pp.32-37
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• 2008

Freestanding hydride vapor phase epitaxy grown GaN(Gallium Nitride) substrates subjected to various polishing methods were characterized for their surface and subsurface conditions, Although CMP(Chemical Mechanical Polishing) is one of the best approaches for reducing scratches and subsurface damages, the removal rate of Ga-polar surface in CMP is insignificant($0.1{\sim}0.3{\mu}m$/hr) as compared with that of N-polar surface, Therefore, conventional MP(Mechanical Polishing) is commonly used in the GaN substrate fabrication process, MP of (0001) surface of GaN has been demonstrated using diamond slurries with different abrasive sizes, Diamond abrasives of size ranging from 30nm to 100nm were dispersed in ethylene glycol solutions and mineral oil solutions, respectively. Significant change in the surface roughness ($R_a$ 0.15nm) and scratch-free surface were obtained by diamond slurry of 30nm in mean abrasive size dispersed in mineral oil solutions. However, MP process introduced subsurface damages confirmed by TEM (Transmission Electronic Microscope) and PL(Photo-Luminescence) analysis.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.8
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• pp.1020-1027
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• 2007

As a national enterprise has been expanded over and over, the worldwide energy consumption has been growing necessarily. Moreover, as recently energy spendings are on the increase in countries such as BRICs, it has resulted that a rise in the price of both oil and mineral resources and instability between supply and demand become serious issue in the world resources market. The recent high price of oil and mineral resources have a deep influence on economy and threaten energy security and even national prosperity of Korea. In addition to these, exhaustion of fossil fuels and the enhanced greenhouse effect which results from gases emitted as a result of fossil fuels has been in serious questions which occur a great deal of effort to secure clean energy resources all around the world. As it is considerably possible for Korea that the Kyoto protocol may come into effect on and after 2013, it is essential to require the technological development to promote energy efficiency as well as to develope safe and renewable energy resources. The wind energy technology which converts kinetic energy into electrical energy has been in the focus of the world's attention. In this study, two-dimensional numerical analyses were conducted to observe subsidence aspects of the sea bottom on differently applied loads and various ground conditions.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.173-178
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• 2007

Time-lapse electrical resistivity measurements have been made in a scale model experiment for geological $CO_2$ sequestration in aquifer. Three types of $CO_2$ injection are tested in a water tank filled with glass beads. These are $CO_2$ dissolved into filtered tap water, $CO_2$ gas, and mineral oil. The mineral oil is a substitute for liquid phase of supercritical $CO_2$. For reconstructing three-dimensional resistivity images, we measure potential differences at 32 potential dipoles on the top surface of the tank due to two current dipoles on the front and back sides. The resultant resistivity images clearly show the movement of injected $CO_2$ in aquifer.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.3
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• pp.253-260
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• 2021

The implementation of subsea separation and liquid boosting is becoming a common development scheme for the exploration of deep water fields. Subsea separation is an attractive and economic solution to develop deep offshore fields producing fluid without hydrate or wax. A subsea separator can avoid or simplifying costly surface platforms of floating vessels, as well as being an efficient tool to enhance hydrocarbon production. Subsea separation system should be reliable to ensure successful operation in a wide range of 3-phase flow regime. In this study, multiphase flow characteristics inside in-line type subsea separation system are investigated for the design of subsea separation system.