• Tunnel and Underground Space
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• v.28 no.4
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• pp.293-303
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• 2018

Monitoring is the act of collecting and analyzing accurate engineering information using various methods and instruments. The purposes of the monitoring are design verification, construction management, quality control, safety management, and diagnose of structure etc.. The diagnose evaluation of the geotechnical structures corresponds to the confirmation of the structural performance. It is aimed to judge the soundness of geotechnical structures considering the degree of damage due to the environmental change and elapsed time. Recently, microseismicity, which is widely known in Korea, can be used for safety management and diagnoses of structure as it detects the micro-damage without disturbance of the structure. This report provides guideline on the procedure for assessing an underground oil storage cavern using microseismic monitoring techniques. Guidelines cover the selection of monitoring systems, sensor array, sensor installation and operation of systems, and interpretation.

• Journal of Adhesion and Interface
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• v.9 no.2
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• pp.8-15
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• 2008

Microcapsules have been widely used in cosmetics and pharmacology as controlled delivery devices of various active materials. Chitosan is the second most plentiful natural biopolymer with biocompatibility and nontoxicity. The chitosan microcapsules were prepared by the water-in-oil (W/O) emulsion method using glutaraldehyde as a crosslinking agent. Span80 was used as an emulsifier, and mineral oil was used as a medium material. Perfectly spherical microcapsules were obtained in the size range of $2{\sim}10{\mu}m$. The effects of emulsifier concentration and stirring speed on the average particle size and distribution were investigated. Encapsulation and release behavior of the microcapsules with different amount of the crosslinking agent (glutaraldehyde), different chitosan contents and different emulsifier concentration conditions were also investigated. The release rate of riboflavin was controlled by the crosslinking density of the chitosan and amount of emulsifier in the preparation of the microcapsule.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.4
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• pp.439-452
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• 1994

One of the chlorofluorocarbon compounds. R-12 deplete atmospheric ozone. It leads to international agreement to reduce CFC production. R-134a has similar thermodynamic properties to CFC-12. It has zero ODP(Ozone Depletion Potential). This Paper focuses on the lubricating oils for using with R-134a PAGs(Polyalkylene Glycol's) and esters are primary lubricants that are now being tested for use with R-134a Because of extreme polarity of R-134a. there are many problems in the selection of lubricating oil. This investigation analyzes compressor working conditions and calculates wear parts friction for simulation testing. Miscibility and material compatibility is proved by sealed glass tests. Friction was tested on the closed type pin on disk wear tester. This equipment simulates actual refrigerating compressor. Environment controlled test made more reliable result than field test Conventional oils(mineral oils, Alkylbenzene, PAO(Polyalpha Olefin) are immiscible with R-134a. PAGs and ester oils are miscible with R-134a. Friction coefficient is similar to conventional system(mineral oil/R-12 systems) at operating condition. At start & stop condition, PAGs/R-134a system has high friction coefficient. It provide reliable result on the lubricity, miscibility, material compatibility of R-134a with these new lubricants. It suggests proper selection of refrigeration oil that may improve compressor durability of performance.

• Tunnel and Underground Space
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• v.23 no.1
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• pp.1-12
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• 2013

Enhanced oil recovery (EOR) technology coupled with underground carbon dioxide sequestration is introduced. $CO_2$ can be injected into an oil reservoir in order to enhance oil production rate and $CO_2$ EOR can be turned into CCS in a long term sense. Coupling $CO_2$ EOR with CCS may secure a large scale and consistent $CO_2$ source for EOR, and the $CO_2$ EOR can bring an additional economic benefit for CCS, since the benefit from enhanced oil production by $CO_2$ EOR will compensate costs for CCS implementation. In this paper, we introduced the characteristics of $CO_2$ EOR technology and its market prospect, and reviewed the Weyburn $CO_2$ EOR project which is the first large-scale $CO_2$ EOR case utilizing an anthropogenic $CO_2$ source. We also introduced geotechnical elements for a successful and economical implementation of $CO_2$ EOR with CCS and they were a miscroseismic monitoring during and after injection of $CO_2$, and determination of minimum miscible pressure (MMP) and maximum injection pressure (MIP) of $CO_2$.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.90-103
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• 2018

This paper presents the development of two ANN models which can predict an optimum production rate by controlling choke size in oil well, and gas injection rate in gas-lift well. The input data was solution gas-oil ratio, water cut, reservoir pressure, and choke size or gas injection rate. The output data was wellhead pressure and production rate. Firstly, a range of each parameters was decided by conducting sensitive analysis of input data for onshore oil well. In addition, 1,715 sets training data for choke size decision model and 1,225 sets for gas injection rate decision model were generated by nodal analysis. From the results of comparing between the nodal analysis and the ANN on the same reservoir system showed that the correlation factors were very high(>0.99). Mean absolute error of wellhead pressure and oil production rate was 0.55%, 1.05% with the choke size model, respectively. And the gas injection rate model showed the errors of 1.23%, 2.67%. It was found that the developed models had been highly accurate.

• Geomechanics and Engineering
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• v.18 no.2
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• pp.205-213
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• 2019

A calculation model of reservoir pressure field distribution around multiple production wells in a heavy oil reservoir is established, which can overcome the unreasonable uniform-pressure value calculated by the traditional mathematical model in the multiwell mining areas. A calculating program is developed based on the deduced equations by using Visual Basic computer language. Based on the proposed mathematical model, the effects of drainage rate and formation permeability on the distribution of reservoir pressure are studied. Results show that the reservoir pressure drops most at the wellbore. The farther the distance away from the borehole, the sparser the isobaric lines distribute. Increasing drainage rate results in decreasing reservoir pressure and bottom-hole pressure, especially the latter. The permeability has a significant effect on bottom hole pressure. The study provides a reference basis for studying the dynamic pressure field distribution before thermal recovery technology in heavy oilfield and optimizing construction parameters.

• KSTLE International Journal
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• v.3 no.1
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• pp.30-37
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• 2002

There have been significant improvements in base oil quality in order to satisfy recent market needs. In particular requirements of passenger car motor oils have been leading the trend. Now, high quality base oils such as VHVI base oils and PAOs are to be formulated in order to meet the tight volatility specifications. The severe hydrocracking, hydro-isomerized dewaxing and hydro-finishing process with noble-metal based catalysts (named UCO lube process) developed by SK corporation has been introduced as one of economic hydroprocessing routes to produce high quality VHVI base oils and food grade white mineral oils from fuels hydrocracker residue. Product quality of UCO lube process is similar to PAO in. general performances and therefore provides satisfactory performance far all straightforward applications in general lubricants. However, when applied to specialty lubricants like transformer oils, spray oils and coning oils, severely hydrocracked base oils are known to have various compatibility problems with gas or surfactants formulated in them. These problems are related to the difference in their composition; inherent high paraffin contents and lack of dissolving ability, Fortunately, it was found that excellent specialty lubricants could be made by carefully selecting and formulating adequate additives and/or aromatic compounds. Moreover, these specialties with high quality VHVI base oils ofter various advantages over conventional base oil based products.

• Resources Recycling
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• v.29 no.6
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• pp.15-26
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• 2020

In recent years, there is an increasing interest in environmental friendly treatment of waste-plastics in terms of the generation of microplastics. Accordingly, the recycling of waste-plastics is very important because it provides advantages of volume reduction, mitigation of carbon dioxide emission, and reproduction of value-added products. In particular, in order to recycle the eco-friendly waste-plastics, it is necessary to use a physical separation methods, and among them, flotation separation, which can separate material (i.e., polymer component) in waste-plastics is well known as a very effective separation method in terms of material recycle. Therefore, in this review, the research trend of flotation separation for effective separation of mixture waste-plastics was investigated. In addition, through the reported research results, approaches to use as new functional materials from polymers, which are raw materials for waste-plastics, are summarized.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.4
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• pp.473-483
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• 1996

To protect the ozone layer, R22 will be replaced with HFCs. R407C is a leading candidate as alternative refrigerant for air conditioner due to its similar thermodynamic characteristics with R22. In replacing R22 with R407C, the compatibility with lubricating oil is of major concern. Polyol ester (POE) oil among the synthetic oils is considered to be the best lubricant for use with R407C because of good electrical properties and miscibility. However, lubricating ability of mixture of R407C/POE oil is lower than that of R22/mineral oil due to the production of acid by hydrolysis which causes corrosive wear. Therefore, to minimize water content, it is needed to develop a molecular sieve desiccant which is compatible with R407C and ester oil. This paper discusses (1) the change of properties of POE oil when current molecular seive is used, (2) the effects of POE oils and additives on durability of compressor. Through compressor life test and bench wear test, it was found that inadequate use of POE oils and additives may promote the deteriation of molecular sieve, resulting in decrease of durability of compressor.

• Korean Journal of Microbiology
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• v.44 no.1
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• pp.22-28
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• 2008

Cutting oils are emulsionable fluids widely used in metal working processes. Their composition is mineral oil, water, and additives (fatty acids, surfactants, biocides, etc.) generating a toxic waste after a long use. Cutting oils also affect colour, taste and odour of water, making it undesirable for domestic and industrial uses. In these days, conventional treatment methods as evaporation, membrane separation or chemical separation have major disadvantages since they generate a concentrated stream that is more harmful than the original waste. In this study, our purpose is to reduce cutting oils by using biological treatment. Eighty one strains were isolated from cutting waste oil of industrial waste water sludge under aerobic conditions. Among these strains, KS47, which removed 90.4% cutting oil in 48 hr, was obtained by screening test under aerobic conditions(pH 7, $28^{\circ}C$). KS47 was identified as Pseudomonas aeruginosa according to morphological, physiological and biochemical properties, 16S rDNA sequence, and fatty acid analysis. P. aeruginosa KS47 could utilize cutting oil as carbon source. In batch test, we obtained optimal degradation conditions(1.5 g/L cell concentration, pH 7, and temperature $30^{\circ}C$). Under the optimal conditions, 1,060 mg/L cutting oil was removed 83.7% (74.1 mg/L/hr).