• Journal of Surface Science and Engineering
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• v.33 no.5
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• pp.349-355
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• 2000

Indium tin oxide (ITO) thin films have been deposited on PET (polyethylene terephthalate) and glass substrates by a do magnetron sputter method of powder target without heat treatments such as substrate heater and post heat treatment. During the sputtering deposition, sputtering parameters such as sputtering power, working pressure, oxygen gas mixture, film thickness and substrate-target distance are important factors for the high quality of ITO thin films. The structural, electrical and optical properties of as-deposited ITO oxide films are investigated by sputtering power, oxygen partial pressure and films thickness among the several sputtering conditions. XRD patterns of ITO films are affected by sputtering power and pressure. As the power and pressure are increased, (411) and (422) peaks of ITO films are grown strongly. Electrical resistivity is also increased, as the sputtering power and pressure are increased. Transmittance of ITO thin films in the visible light ranges is lowered with an increase of sputtering power and film thickness. Reflectance of ITO films in infra-red region is decreased, as the power and pressure is increased.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.7
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• pp.593-600
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• 2015

In this study, a combined hybrid rocket system is newly introduced which has characteristics of both gas generators and afterburner type hybrid rockets. In particular, a combined gas generator utilizing solid fuel and liquid/gas oxidizer was designed as a primary combustor of the system. Combustion tests were carried out with various equivalence ratio affected by parameters such as fuel length, oxidizer flow rate, fuel port diameter and fuel type. In general, fuel-rich gas generator produces low combustion gas temperature to meet the temperature requirement and the target temperature was transiently set less than 1600 K. Since it was found that controlling parameters showed limited effects on the change of equivalence ratio, mixture of $O_2$ and $N_2$ as an oxidizer was additionally introduced. As a result, a combined gas generator successfully produced combustion gas temperature of less than 1600 K Future studies will carry out more combustion tests to attain fuel-rich combustion gas temperature less than 1200 K, which was a temperature requirement of a gas generator system in the previous studies.

• Korean Journal of Materials Research
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• v.21 no.9
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• pp.486-490
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• 2011

Nano-indium-coated ZnO:In thick films were prepared by a hydrothermal method. ZnO:In gas sensors were fabricated by a screen printing method on alumina substrates. The gas sensing properties of the gas sensors were investigated for hydrocarbon gas. The effects of the indium concentration of the ZnO:In gas sensors on the structural and morphological properties were investigated by X-ray diffraction and scanning electron microscopy. XRD patterns revealed that the ZnO:In with wurtzite structure was grown with (1 0 0), (0 0 2), and (1 0 1) peaks. The quantity of In coating on the ZnO surface increased with increasing In concentration. The sensitivity of the ZnO:In sensors was measured for 5 ppm $CH_4$ gas and $CH_3CH_2CH_3$ gas at room temperature by comparing the resistance in air with that in target gases. The highest sensitivity to $CH_4$ gas and $CH_3CH_2CH_3$ gas of the ZnO:In sensors was observed at the In 6 wt%. The response and recovery times of the 6 wt% indiumcoated ZnO:In gas sensors were 19 s and 12 s, respectively.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.129-136
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• 2017

Climate change is the biggest environmental issue of our times. A variety of activities to reduce greenhouse gas emissions have been in progress to observe the Kyoto Protocol. Especially, the Energy Target Scheme is created to reduce greenhouse emission with the supervision of Korean government. This includes Green-house Gas Information Systems to promote activities in the private sector to reduce green-house gas emissions, to cut a cost of energy use, and to reduce GHG emissions. Also, the system has calculated the amount of greenhouse gases. Without any additional investment, 2.75% savings are increased over the previous year. In service sector, a cooperation of customers and employees is necessary. A reduction of GHG emissions requires a proper service organization, considering an amount of investment and payback period. Without any additional investment or replacement, employees can save energy easily turning off ventilation systems an hour before employees' departure, installing timers to turn off water purifiers and vending machines after some period of no use. The Green-house Gas Information System is similar to that of Environmental Management System. However, the Excel is the best program to calculate an amount of green-house gas emissions, and to assess for a reduced amount of GHG emissions. A goal of this research is to propose a practical method in the private sector to calculate an amount of green-house gases. The Green-house gas Information System based on Excel spreadsheet gives standards for good evaluation. The greenhouse gas information system establishes and executes the policies and objectives related to greenhouse gas emissions Similar to ISO 14001 environment management system structures, the advantages of using simplified Excel Sheet for calculating GHG emissions and reducing GHG emissions are easy to access.

• Journal of the Korean Institute of Gas
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• v.26 no.1
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• pp.34-40
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• 2022

Gas cylinder cabinets have risks such as cylinder explosion and scattering of debris when a fire occurs. These risks are likely to cause gas spills and cause secondary damage. In order to reduce damage, it is very important to secure the fire resistance performance of the gas cylinder cabinet. In foreign countries, NFPA codes in the United States and EN-14470-2 in Europe stipulate fire resistance test standards for gas cylinder cabinets to protect internal cylinders for a certain period of time in a situation where gas cylinder cabinets are exposed to flames. However, in Korea, only internal pressure performance and airtight performance standards are specified, and the target is limited to piping, and research and regulations for the fire resistance performance of gas cylinder cabinets are insufficient compared to overseas. Therefore, in this study, finite element analysis was used to establish fire resistance standards for domestic gas cylinder cabinets. In the event of a fire, optimal conditions are derived in terms of structure and material.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.665-670
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• 2016

Prevailing dissemination of machine tools and cutting technology have caused drastic developments of high speed dry machining with work materials of high hardness, and demands on the high-hardness-materials with high efficiency have become increasingly important in terms of productivity, cost reduction, as well as environment-friendly issue. Addition of Si to TiAlN has been known to form nano-composite coating with higher hardness of over 30 GPa and oxidation temperature over $1,000^{\circ}C$. However, it is not easy to add Si to TiAlN by using conventional PVD technologies. Therefore, Ti-Al-Si-N have been prepared by hybrid process of PVD with multiple target sources or PVD combined with PECVD of Si source gas. In this study, a single composite target of Ti-Al-Si was prepared by powder metallurgy of MA (mechanical alloying) and SPS (spark plasma sintering). Properties of he resulting alloying targets were examined. They revealed a microstructure with micro-sized grain of about $1{\sim}5{\mu}m$, and all the elements were distributed homogeneously in the alloying target. Hardness of the Ti-Al-Si-N target was about 1,127 Hv. Thin films of Ti-Al-Si-N were prepared by unbalanced magnetron sputtering method by using the home-made Ti-Al-Si alloying target. Composition of the resulting thin film of Ti-Al-Si-N was almost the same with that of the target. The thin film of Ti-Al-Si-N showed a hardness of 35 GPa and friction coefficient of 0.66.

• Journal of environmental and Sanitary engineering
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• v.21 no.1 s.59
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• pp.44-51
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• 2006

This study was conducted to investigate air quality in the underground parking lot of department store. Sampling sites were selected to the three sites in one department store. Measuring instrument started from November 3rd, 2005 to November 9, 2005. Target air quality parameters include a number of criteria pollutants such as NOx, $O_3$. The purpose of this study was to find out the present condition of indoor air quality in underground parking space of department store. Through the field measurement, the current situation and the behavior of contaminants were investigated and then was compared with the advice standards. The result of this study was as follows; The Average density of NOx gas and $O_3$ gas was maintained below the indoor air advice standards. The Average density of NOx gas and $O_3$ gas was highly measured during the weekend than during the week day. Average density of NOx gas and $O_3$ gas was highly measured at daytime than that of afternoon. Average density of NOx gas was highly measured in the center area than the other area. Average density of $O_3$ gas was highly measured at the entrance than the other area. NOx gas concentration was maintained below 0.3ppm, an average for 1 hours, as defined in the parking space law. $O_3$ gas concentration was maintained below 0.08ppm, an average for 1 hours, as defined in the parking space law.

• Molecules and Cells
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• v.42 no.5
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• pp.397-405
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• 2019

The regulatory role of long noncoding RNA (lncRNA) growth arrest-specific transcript 5 (GAS5) in both cancerous and noncancerous cells have been widely reported. This study aimed to evaluate the role of lncRNA GAS5 in heart failure caused by myocardial infarction. We reported that silence of lncRNA GAS5 attenuated hypoxia-triggered cell death, as cell viability was increased and apoptosis rate was decreased. This phenomenon was coupled with the down-regulated expression of p53, Bax and cleaved caspase-3, as well as the up-regulated expression of CyclinD1, CDK4 and Bcl-2. At the meantime, the expression of four heart failure-related miR-NAs was altered when lncRNA GAS5 was silenced (miR-21 and miR-142-5p were up-regulated; miR-30b and miR-93 were down-regulated). RNA immunoprecipitation assay results showed that lncRNA GAS5 worked as a molecular sponge for miR-142-5p. More interestingly, the protective actions of lncRNA GAS5 silence on hypoxia-stimulated cells were attenuated by miR-142-5p suppression. Besides, TP53INP1 was a target gene for miR-142-5p. Silence of lncRNA GAS5 promoted the activation of PI3K/AKT and MEK/ERK signaling pathways in a miR-142-5p-dependent manner. Collectively, this study demonstrated that silence of lncRNA GAS5 protected H9c2 cells against hypoxia-induced injury possibly via sponging miR-142-5p, functionally releasing TP53INP1 mRNA transcripts that are normally targeted by miR-142-5p.

• Membrane Journal
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• v.31 no.5
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• pp.327-332
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• 2021

The use of membranes for MBRWG (Membrane Bioreactor for Waste Gas) treatment can provide highly selective separation of a waste gas stream followed by effective biological removal. MBRWG have several potential advantages, among which the most distinctive one is separation of gas and liquid phases at each side of membrane potentially allowing the optimal biomass control toward effective biodegradation of target gases as well as biofilm activation. This advantage becomes especially favorable for removal of hydrophobic toxic gases, such as xylene, by MBRWG systems, because the mass transfer, the toxicity, and thereby the biodegradation of hydrophobic gas treatment requires sensitive handling of liquid stream and water control near biofilm. Among various membranes for MBRWG treatment, PDMS-hollow fiber membranes provide the high gas mass transfer. Despite lower specific surface areas, capillary type membranes are also applied current MBRWG studies. In addition to the main application of membranes as biofilm supporter in MBRWG systems, there can be another application of membranes in a posterior process for removal of residual gases or dusts emitted from conventional biological waste gas treatment processes.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.73-83
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• 2014

CFD(computational fluid dynamics) model is developed to simulate direct injection of ammonia gas phase from ammonia transporting materials into the SCR catalyst in the exhaust pipe of the engine with solid SCR. Configurations of one-hole and four-hole nozzle, circumferential type, porous tube type, and the effect of mixer configurations which commonly used in liquid injection of AdBlue are considered for complex geometries. Mal-distribution index related to concentration of ammonia gas, flow uniformity index related to velocity distribution, and pressure drop related to flow resistance are compared for different configurations of complex geometries at the front section of SCR catalyst. These results are used to design the injection system of ammonia gas phase for solid SCR of target vehicle.