• Journal of the Korean Society of Safety
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• v.36 no.4
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• pp.1-11
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• 2021

Piping systems comprising pumps and valves are essential in the power plant, oil, and defense industry. Their purpose includes a stable supply of the working fluid or ensuring the target system's safe operation. However, piping system accidents due to leakage of toxic substances, explosions, and natural disasters are prevalent In addition, with the limited maintenance personnel, it becomes difficult to detect, isolate, and reconfigure the damage of the piping system and recover the unaffected area. An autonomous recovery piping system can play a vital role under such circumstances. The autonomous recovery algorithms for the piping system can be divided into low-pressure control algorithms, hydraulic resistance control algorithms, and flow inventory control algorithms. All three methods include autonomous opening/closing logic to isolate damaged areas and recovery the unaffected area of piping systems. However, because each algorithm has its strength and weakness, appropriate application considering the overall design, vital components, and operating conditions is crucial. In this regard, preliminary research on algorithm's working principle, its design procedures, and expected damage scenarios should be accomplished. This study examines the characteristics of algorithms, the design procedure, and working logic. Advantages and disadvantages are also analyzed through simulation results for a simplified piping system.

• Journal of The Korean Society of Clinical Toxicology
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• v.2 no.1
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• pp.31-36
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• 2004

Three workers, field operators in lubricating oil processing of petroleum refinery industry were found unconscious by other worker. One of them who were exposed to an high concentration of H2S was presented with Glasgow Coma Score of 5, severe hypoxemia on arterial blood gas analysis, normal chest radiography, and normal blood pressure. On hospital day 7, his mental state became clear, and neurologic examination showed quadriparesis, profound spasticity, increased tendon reflexes, abnormal Babinski response, and bradykinesia. He was also found to have decreased memory, attention deficits and blunted affect which suggest general cognitive dysfunction, which improved soon. MRI scan showed abnormal signals in both basal ganglia and motor cortex, compatible with clinical findings of motor dysfunction. Neuropsychologic testing showed deficits of cognitive functions. SPECT showed markedly decreased cortical perfusion in frontotemporoparietal area with deep white matter. Another case was recovered completely, but the other expired the next day.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.688-706
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• 2024

Austenitic stainless steels (ASS) are extensively employed in various sectors such as nuclear, power, petrochemical, oil and gas because of their excellent structural strength and resistance to corrosion. SS304 and SS316 are the predominant choices for piping, pressure vessels, heat exchangers, nuclear reactor core components and support structures, but they are susceptible to stress corrosion cracking (SCC) in chloride-rich environments. Over the course of several decades, extensive research efforts have been directed towards evaluating SCC using diverse methodologies and models, albeit some uncertainties persist regarding the precise progression of cracks. This review paper focuses on the application of Acoustic Emission Technique (AET) for assessing SCC damage mechanism by monitoring the dynamic acoustic emissions or inelastic stress waves generated during the initiation and propagation of cracks. AET serves as a valuable non-destructive technique (NDT) for in-service evaluation of the structural integrity within operational conditions and early detection of critical flaws. By leveraging the time domain and time-frequency domain techniques, various Acoustic Emission (AE) parameters can be characterized and correlated with the multi-stage crack damage phenomena. Further theories of the SCC mechanisms are elucidated, with a focus on both the dissolution-based and cleavage-based damage models. Through the comprehensive insights provided here, this review stands to contribute to an enhanced understanding of SCC damage in stainless steels and the potential AET application in nuclear industry.

• Applied Chemistry for Engineering
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• v.25 no.5
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• pp.520-525
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• 2014

In this paper, the effect of silane-treated silicas and epoxidized soybean oil (ESBO) addition on adhesion properties of silicas-filled epoxy adhesives was examined. The silicas were treated by ${\gamma}$-methacryloxy propyltrimethoxy silane (MPS), ${\gamma}$-glycidoxy propyl trimethoxy silane (GPS), and ${\gamma}$-mercapto propyl trimethoxy silane (MCPS). Surface and structural properties of the adhesives were determined by using scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). The t-peel strength of the adhesives was estimated using the universal testing machine (UTM). And, the equilibrium spreading pressure, surface free energy, and specific surface area were investigated by BET methods with $N_2$/77 K adsorption. As a result, the peel strength of the adhesives was increased in the presence of silane-treated silicas in the adhesives compared to that of untreated silicas. This result indicated that the silane coupling agent played an important role in improving the dispersion of silicas in epoxy adhesives. And, the adhesives treated by MCPS were superior to the others in adhesion.

• The Journal of Engineering Geology
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• v.12 no.1
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• pp.35-51
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• 2002

This study aims to establish the methodology for design of an optimum water curtain system of the unlined underground oil storage cavern satisfying the requirements of hydrodynamic performance in a volcanic terrain of the south coastal area. For the optimum water curtain system in the storage facility, the general characteristics of groundwater flow system in the site are quantitatively described, i.e. distribution of hydraulic gradients, groundwater inflow rate into the storage caverns, and hydrogeologic influence area of the cavern. In this study, numerical models such as MODFLOW, FracMan/MAFIC and CONNECTFLOW are used for calculating the hydrogeological stability parameters. The design of a horizontal water curtain system requires considering the distance between water curtain and storage cavern, spacing of the water curtain boreholes, and injection pressure. From the numerical simulations at different scales, the optimum water curtain systems satisfying the containment criteria are obtained. The inflow rates into storage caverns estimated by a continuum model ranged from about 120 m$^3$/day during the operation stage to 130~140m$^3$/day during the construction stage, whereas the inflow rates by a fracture network model are 80~175m$^3$/day. The excavation works in the site will generate the excessive decline of groundwater level in a main fracture zone adjacent to the cavern. Therefore, the vertical water curtain system is necessary for sustaining the safe groundwater level in the fracture zone.

• Korean Journal of Medicinal Crop Science
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• v.12 no.6
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• pp.508-514
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• 2004

Chrysanthemum boreale M. is an important medicinal plant that has been historically used in herbal medicine and in the health food throughout East Asia. This study was conducted to investigate the influence of abscisic acid (ABA) and salicylic acid (SA) on plant growth, mineral content and effective components, such as essential oil, amino acid and cumambrin A, by means in order to increase the productivity and the quality of flowerheads in the plant. Yields of flowerheads were increased by 12.7%, 21.7% and 15.5% by ABA, SA and both treatments, respectively, as compared with the control. Inorganic nutrient content was changed by PGRs; SA treatment was increased by nitrogen, phosphorus and magnesium content but decreased by potassium of C. boreale M. flowerheads. Total content of amino acid was increased by SA but decreased by ABA treatment. Essential oil content and yields were increased to 9.7% and 33.8% by SA treatment. Moreover, the content of terpene, monoterpenoids and sesquiterpenoids, were improved by ABA treatment, especially, germacrene-D content was increased by 39.1%, as compared to control. In addition, yields of cumambrin A, sesquiterpene compound exhibiting blood-pressure activity, increased in all PGRs treatments, but its concentration in the C. boreale M. flowerheads only increased by ABA and both treatment. The experiment suggests that PGRs using ABA and SA could increase the yields and quality of C. boreale M. flowerheads.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.585-591
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• 2017

Turbocharging is widely used in diesel and gasoline engines as an effective way to reduce fuel consumption. But turbochargers have turbo-lag due to mechanical friction losses. Bearing friction losses are a major cause of mechanical friction losses and are particularly intensified in the lower speed range of the engine. Current turbochargers mostly use oil bearings (two journal bearings and one thrust bearing). In this study, we focus on the bearing friction in the lower speed range. Experimental equipment was made using a drive motor, load cell, magnetic coupling, and oil control system. We measured the friction losses of the turbocharger while considering the influence of the rotation speed, oil temperature, and pressure. The friction power losses increased exponentially when the turbocharger speed increased.

• Journal of fish pathology
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• v.33 no.1
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• pp.97-101
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• 2020

Although aquaculture production rates grown over the years, aquatic animal diseases occur every year which causes substantial economic losses. When an aquatic animal is infected with an aquatic animal pathogen it is either incinerated or buried according to the aquatic life disease control act. Although these methods prevent the spread of disease, it is not environment friendly. Here, we developed an aquatic animal rendering equipment for disposal of fish waste which is environment-friendly and efficient. Also, fertilizer components of fish waste were evaluated value for recycling. The mobile rendering equipment was designed for field operation and/or high temperature and pressure system, oil and water separator, and shredding drying apparatus. During the experiment (July-2016 to November-2016), a total of 53,824 kg fish waste was collected, and 29,216 kg compost of rendering by-product was made. Also, compost made from viral (Viral hemorrhagic septicemia virus) infected fish did not reflect any detectable pathogen. The concentration of nitrogen, phosphorus, and organic matter in the fish waste compost were 2.17%, 26.98%, and 92.44%, respectively. The results suggest that fish waste used in this study was decomposed efficiently as per the official standard for fertilizer product. This equipment can be useful for efficient inactivation of the aquatic animal pathogenic agents and recycling of the fish waste in an environment-friendly manner.

• Geomechanics and Engineering
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• v.20 no.6
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• pp.537-546
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• 2020

Oil and natural gas reserves have been recognised abundantly in clayey rich rock formations in deep costal reservoirs. It is necessary to understand the sedimentary history of those reservoir rocks to well explore these natural resources. This work designs a group of laboratory experiments to mimic the physical process of the sedimentary clay-rich rock formation. It presents characterisation results of the physical properties of the artificial clayey rocks synthesized from illite clay, quartz sand and brine water by high-pressure consolidation tests. Special focus is given on the effects of illite clay content and high-stress consolidation on the physical properties. Multi-step loaded consolidation experiments were carried out with stress up to 35 MPa on mixtures constituting of the illite clay, quartz sand and brine water with five initial illite clay contents (w=85%, 70%, 55%, 40% and 25%). Compressibility and void ratio were characterised throughout the physical compaction process of the mixtures constituting of five illite clay contents and their water permeability was measured as well. Results show that the applied stress induces a great reduction of clayey rock void ratio. Illite clay contents has a significant influence on the compressibility, void ratio and the permeability of the physically synthesized clayey rocks. There is a critical illite clay content w=70% that induces the minimum void ratio in the physically synthesised clayey rocks. The SEM study indicates, in the high-pressure synthesised clayey rocks with high illite clay contents, the illite clay minerals are located in layers and serve as the material matrix, and the quartz minerals fill in the inter-mineral pores or are embedded in the illite clay matrix. The arrangements of the minerals in microscale originate the structural anisotropy of the high-pressure synthesised clayey rock. The test findings can give an intuitive physical understanding of the deep-buried clayey rock basins in energy reservoirs.

• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.39-48
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• 2023

This study presents the experimental results to measure the adsorption amount of methane gas by coal according to the conditions of a coalbed methane (CBM) reservoir. Adsorbed gas to coal seam particles was measured under reservoir conditions (normal pressure ~ 1,200 psi pressure range, temperature range15 ~ 45℃) using coal samples obtained from random mines in Kalimantan Island, North Indonesia. The obtained amount of absolute adsorbed gas was applied to triangular with linear interpolation to calculate the maximum amount of adsorbed gas according to temperature and pressure change, at which no experiment was performed. As a result, it was revealed that the amount of adsorbed gas to coal particles increased as the pressure increased and temperature decreased, but the increase of the amount of adsorbed gas decreased at more than an appropriate depth(1,000 ft). In the cleat permeability and cleat porosity for each depth of the coal bed considering the effective stress, the cleat permeability was 28.86 ~ 46.81 md, and the cleat porosity was 0.83 ~ 0.98%. This means that the gas productivity varies significantly with the depth because the reduction of the permeability according to the depth in the coal seam is significant. Therefore, a coalbed depth should be considered essential when designing the spacing of production wells in a coalbed methane reservoir in further study.