• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.44-51
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• 2018

As the LNG storage tank is aged, if there is a crack in the outer wall concrete or corrosion of the reinforcing steel, there is a risk of a major accident such as collapse of the structure depending on the type and degree of damage. Since 2014, LNG storage tanks have undergone precise safety diagnosis and safety inspection has been carried out. The condition evaluation criteria for each component have been revised and applied in January 2016. The condition evaluation standard is to evaluate the status of storage tanks based on the appearance survey and material test results of LNG storage tanks and it is important for maintenance. In addition, the representative condition evaluation standard that shows the comprehensive state of each LNG storage tank is important in maintenance, but the related standard for LNG storage tank outer concrete is not available in Korea and abroad, and development of the condition evaluation standard is necessary. In this paper, we examined the structural characteristics of LNG storage tanks, analyzed the status of the condition evaluation criteria for each member, and developed a comprehensive status rating system by weighting the members. We used the AHP(Analytic Hierarchy Process) technique and developed a representative conditon evaluation criteria through surveys of professional organizations.

• Journal of Sensor Science and Technology
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• v.30 no.4
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• pp.210-217
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• 2021

Gas sensors based on semiconducting metal oxides have attracted considerable attention for various applications owing to their facile, cheap, and small-scale manufacturing processes. Hematite (α-Fe₂O₃) is widely considered as a promising candidate for a gas-sensing material owing to not only its abundance in the earth's crust and low price but also its chemical stability and suitable bandgap energy. However, only a few studies have been performed in this direction because of the low gas response and sluggish response of hematite-based gas sensors. Nanostructures present a representative solution to both overcome these disadvantages and exploit the desirable features to produce high-performance gas sensors. However, several challenges remain for adopting gas sensors based on metal oxide nanostructures, such as improving cost efficiency and facilitating mass production. This review summarizes the recent studies on gas sensors based on hematite nanostructures. It also provides useful insights into various strategies for enhancing the gas-sensing properties of gas sensors based on hematite nanostructures.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.222-227
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• 2000

At representative thermoeconomic theory to determine the unit cost of multiple products, there are the $\ulcorner$SPECO$\lrcorner$ method of Tsatsaronis's study group and the $\ulcorner$MOPSA$\lrcorner$ method of chung-ang university phase laboratory. Against this theory, we propose new theory called $\ulcorner$Thermoeconomics to divide the exergetic cost into each working fluid$\lrcorner$ in this study. Also, we apply new thermoeconomic theory to CGAM problem (30MW-grade imaginary gas turbine cogeneration power plant) that it is representative power system in thermoeconomics theory, and we fixed to interpreted the unit cost of electricity on the part of gas turbine and the unit cost of steam exergy(enthalpy) on the part of HRSG.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.417-422
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• 2010

Low temperature diesel combustion was achieved via a combination of late injection timing ($8.5^{\circ}$ CA BTDC to $0.5^{\circ}$ CA BTDC) and heavy exhaust gas recirculation (37% to 48%) with ultra low sulfur Swedish diesel fuel in a 1.7L common rail direct injection diesel engine. When injection timing is retarded at a certain exhaust gas recirculation rate, the particulate matter and nitrogen oxides decease simultaneously, while the hydrocarbon and carbon monoxide increase. Hydrocarbon speciation by gas chromatography using a flame ionization detector reveals that the ratio of partially burned hydrocarbon, i.e., mainly alkenes increase as the injection timing is retarded and exhaust gas recirculation is increased. The two most abundant hydrocarbon species are ethene which is a representative species of partially burned hydrocarbons, and n-undecane, which is a representative species of unburned hydrocarbons. They may be used as surrogate hydrocarbon species for performing a bench flow reactor test for catalyst development.

• Journal of Sensor Science and Technology
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• v.22 no.2
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• pp.162-173
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• 2013

The purpose of this paper is to classify VOC gases by emulating the characteristics found in biological olfaction. For this purpose, we propose new signal processing method based a polymeric chemical sensor array consisting of 4096 sensors which is created by NEUROCHEM project. To remove unstable sensors generated in the manufacturing process of very large scaled chemical sensor array, we used discrete wavelet transformation and cosine similarity. And, to remove the supernumerary redundancy, we proposed the method of selecting candidates of representative sensor representing sensors with similar features by Fuzzy c-means algorithm. In addition, we proposed an improved algorithm for selecting representative sensors among candidates of representative sensors to better enhance classification ability. However, Classification for very large scaled sensor array has a great deal of time in process of learning because many sensors are used for learning though a redundancy is removed. Throughout experimental trials for classification, we confirmed the proposed method have an outstanding classification ability, at transient state as well as steady state.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.354-360
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• 2001

Hybrid energy system of fuel cell and gas turbine is discussed as the system to be used in the distributed power generation. Discussion is first directed to the distributed power generation system which is expected to be more popularly introduced both in urban and isolated areas. In the next some characteristic features of fuel cell and micro gas turbine are shortly described. In the last discussion is turn to the fuel cell and micro gas turbine hybrid system. In particular, performance characteristics of a representative SOFC/MGT hybrid system are investigated through the concept design at various power capacity levels.

• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.99-104
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• 2015

Today the most efficient way to transport the natural gas is carried via the liquid. In order to liquefy the natural gas to be cooled to $-160^{\circ}C$ or less. Cooling method has a number of different ways. In this paper, we studied control method for the representative liquefaction process, C3MR. Natural gas liquefaction control is a tool that can maintain the quality of natural gas is a means to ensure stable operation. Analyzing the C3MR process, and select the control parameters for the control valve. We find control structure for mixed refrigerant cycle through the step response. A control result obtained through the dynamic simulation arbitrarily given a disturbance was found to maintain a steady-state results.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1929-1934
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• 2022

Besides recent progresses in the physics-based modelling of fission gas and helium behaviour, the scarcity of experimental data concerning their combined behaviour (i.e., cocktail) hinders further model developments. For this reason, in this work, we propose a modelling methodology aimed at providing recommendations for accelerated experimental investigations. By exploring a wide range of annealing temperatures and cocktail compositions with a physics-based modelling approach we identify the most interesting conditions to be targeted by future experiments. To corroborate the recommendations arising from the proposed methodology, we include a sensitivity analysis quantifying the impact of the model parameters on fission gas and helium release, in conditions representative of high and low burnup.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.6
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• pp.795-802
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• 2022

Korea is showing its appearance as a leading country in the hydrogen economy by establishing policies for revitalizing the hydrogen economy and enacting the 「Hydrogen Economy Promotion and Hydrogen Safety Management Act」 for the first time in the world. In addition, domestic hydrogen facilities are using hydrogen energy safely through world-class safety management compared to overseas advanced countries. However, in order to enhance the safety of the rapidly diversifying hydrogen industry and rapid technology development, such as the introduction of liquefied hydrogen, some institutional improvements are needed. In this regard, this paper intends to analyze the results of safety inspections on 13 representative facilities and prepare safety improvement plans to establish preemptive safety measures.

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.112-117
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• 2020

Xylene is a hazardous volatile organic compound that should be precisely measured to monitor indoor air quality. However, the selective and sensitive detection of ppm-level xylene using oxide-semiconductor gas sensors remains a challenge. In this study, pure and Cr-doped Co₃O₄ nanoparticles (NPs) were prepared using flame spray pyrolysis, and their gas-sensing characteristics to 5-ppm xylene at 250 ℃ were investigated. The 4 at% Cr-doped Co₃O₄ NPs exhibited a high gas response to 5-ppm xylene (resistance ratio to gas and air = 39.1) and negligible cross-responses to other representative and ubiquitous indoor pollutants such as ethanol, benzene, formaldehyde, carbon monoxide, and ammonia. In this paper, the enhancement of the gas response and selectivity of Co₃O₄ NPs to xylene by Cr doping was discussed in relation to the catalytic promotion of the gas-sensing reaction. This sensor can be used to monitor indoor xylene.