• Transactions on Electrical and Electronic Materials
• /
• v.1 no.2
• /
• pp.23-27
• /
• 2000

Indium in oxide(ITO) films have been deposited on PET and glass substrates by DC reactive magnetron sputtering without post-deposition thermal treatment, The high quality for microstructure, electrical and optical properties of the as-deposited ITO films on unheated substrates is dominated by the sputtering parameters, The influence of the working gas pressure, DC power and oxygen partial pressure has been systematically investigated, The lowest DC power, and oxygen partial pressure has been systematically investigated, The lowest resistivity of ITO films deposited on PET substrates was 6$\times$10$^{-4}$ $\Omega$cm. It has been obtained at a working pressure of 3 mTorr and DC power of 30 W. The sheet resistance and optical transmittance of these film were 22 $\Omega$/square and 84% respectively. The best values of figures of merit for the electrical and optical characteristics such as T/ $R_{sh}$ and $T^{10}$ / $R_{sh}$ are approximately 38.1 and 7.95($\times$10$^{-3}$ $\Omega$$^{-1}$ ), respectively.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.144.1-144.1
• /
• 2013

Recently, we have developed the local oxidization and hydrogenization method for graphene layer using atomic force microscope(AFM) tip at room temperature and ambient pressure. With this method we could create locally oxidized or hydrogenized area on the graphene layer with various size from nanometer to micrometer scale, by controlling the amplitude and polarity of the voltage supplied between conducting AFM tip and the graphene layer. We investigated the chemical states of functionalized C atoms in the graphene layer using scanning photoelectron microscopy. By measuring C 1s core level X-ray Photoemission Spectra of the C atoms and suitable fitting process carried on the measured spectra, we could obtain the fraction of oxidization and hydrogenization under various condition, and the evolution of each chemical state during thermal annealing process.

• Applied Science and Convergence Technology
• /
• v.26 no.4
• /
• pp.62-65
• /
• 2017

Passivation of surface defects by the formation of chemically inert structure at the surface of $TiO_2$ nanocrystals can be potentially useful in enhancing their photocatalytic activity. In this regard, we have studied the surface chemical states of $TiO_2$ surfaces prepared by a treatment in the afterglow of $N_2$ microwave plasma using X-ray photoemission spectroscopy (XPS). We find that nitrogen is incorporated into the surface after the treatment up to a few atomic percent. Interestingly, the surface oxynitride layer is found to be chemically stable when it's in contact with water at room temperature (RT). The surface nitrogen species were also found to be thermally stable upon annealing up to $150^{\circ}C$ in the atmospheric pressure. Thus, we conclude that the treatment of oxide materials such as $TiO_2$ in the afterglow of $N_2$ plasma can be effective way to passivate the surface with nitrogen species.

• Journal of the Korean institute of surface engineering
• /
• v.52 no.5
• /
• pp.246-250
• /
• 2019

Nano-multilayered $Cr_{25.2}Al_{19.5}Si_{4.7}N_{50.5}$ films were deposited on the steel substrate by cathodic arc plasma deposition. They were corroded at $900^{\circ}C$ in $Ar/1%SO_2$ gas in order to study their corrosion behavior in sulfidizing/oxidizing environments. Despite the presence of sulfur in the gaseous environment, the corrosion was governed by oxidation, leading to formation of protective oxides such as $Cr_2O_3$ and ${\alpha}-Al_2O_3$, where Si was dissolved. Iron diffused outward from the substrate to the film surface, and oxidized to $Fe_2O_3$ and $Fe_3O_4$. The films were corrosion-resistant up to 150 h owing to the formation of thin ($Cr_2O_3$ and/or ${\alpha}-Al_2O_3$)-rich oxide layers. However, they failed when corroded at $900^{\circ}C$ for 300 h, resulting in the formation of layered oxide scales due to not only outward diffusion of Cr, Al, Si, Fe and N, but also inward movement of sulfur and oxygen.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.15 no.11
• /
• pp.943-956
• /
• 2003

A numerical program has been developed for the simulation of automotive engine cooling system. The program determines the mass flow rate of engine coolant circulating the engine cooling system and radiator cooling air when the engine speed is adopted by appropriate empirical correlation. The program used the method of thermal balance at individual element through the model for radiator component in radiator analysis. This study has developed the program that predicts the coolant mass flow rate, inlet and outlet temperatures of each component in the engine cooling system (engine, transmission, radiator and oil cooler) in its state of thermal equilibrium. This study also combined the individual programs and united into the total performance analysis program of the engine cooling system operating at a constant vehicle speed. An air conditioner system is also included in this engine cooling system so that the condenser of the air conditioner faces the radiator. The effect of air conditioner to the cooling performance, e.g., radiator inlet temperature, of the radiator and engine system was examined. This study could make standards of design of radiator capacity using heat rejection with respect to the mass flow rate of cooling air. This study is intended to predict the performance of each component at design step or to simulate the system when specification of the component is modified, and to analyze the performance of the total vehicle engine cooling system.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.15 no.2
• /
• pp.10-16
• /
• 2019

In this study, the present regulation of heat metering for the ground source heat pump was investigated. The ground source heat pump has been adopting the heat metering system used in the district heating system for estimating the heating and cooling energy production amount. The accuracy of the present heat metering systems for a water to water ground source heat pump is low, because the system for district heating has a relatively high temperature range comparing with the ground source heat pump operating conditions. Even though the heat amount for the building side should be measured, the heat absorption and extraction amount from or to the ground was measured for the water to air ground source heat pump due to the difficulty of estimating the air side heating and cooling capacity in the present regulation. It is highly recommended to validate the heat metering system to have reliability for the ground source heat pump and develop the system to be applicable water to air ground source heat pump.

• Journal of Mushroom
• /
• v.20 no.4
• /
• pp.193-198
• /
• 2022

The biological efficiencies of promising Pleurotus spp. were evaluated. Pleurotus ostreatus, Pleurotus tuberregium,and Pleurotus sajor-cajuwere investigated at temperatures of 22℃, 20℃, and 18℃ to determine their ability to adapt to temperatures that are likely to be found in subtropical regions. The experiment was conducted using a substrate comprising Popular sawdust 60% + cotton seed 20% + beet pulp 20% under a relative humidity of 65%. The results indicated that there were significant differences in terms of biological efficiency between the species: P. tuber regium 128.84% at 22℃, P. ostreatus 108.41% at 22℃, and P. sajor-caju is 80% at 20℃. The common temperatures at which all species showed the highest biological efficiencies were 22℃ and 20℃. Therefore, the production of the evaluated species was equal to or surpassed biological efficiencies reported in tropical environments, thereby demonstrating a potential opportunity to adapt to tropical environments without compromising quality standards.

• Korean Chemical Engineering Research
• /
• v.61 no.1
• /
• pp.74-79
• /
• 2023

As the demand for hydrogen increases, the facilities for storing hydrogen has been important, and a few laws for hydrogen facilities should be complied. According to the Occupational Safety and Health Act in Korea, in case liquid hydrogen with a storage capacity of 5 tons or more is handled, a Process Safety Management (PSM) system should be complied. However, there are some standards which are not proper for flammable low-temperature liquefied substances on the current Occupational Safety and Health Act. In this study, 7 key points in process safey information and safety operation procedures among PSM components are suggested and how these key points should be improved is derived based on scientific analysis.

• Journal of the Korean Society of Systems Engineering
• /
• v.19 no.1
• /
• pp.107-113
• /
• 2023

For one-shot systems such as 81mm high-explosive ammunition, research on performance prediction is insignificant due to research manpower infrastructure and lack of interest and difficulties in securing field data, which can only be done by special task workers. In order to evaluate the actual range of ammunition, the storage ammunition reliability evaluation checks the range by firing actual ammunition through a functional test. Test evaluation is a method of extracting a sample from the population, launching it, and recording the results accordingly. As a result of these tests, the range, which is an indicator of ammunition performance, can be measured differently according to meteorological factors such as temperature, atmospheric pressure, and humidity according to the location of the test site. In this study, various environmental factors generated at the test site and storage period analyze the correlation with the range, which is the performance of ammunition, and analyze the priority of importance for each factor and the numerical standards that environmental factors affect range. Through this, a new approach to one-shot system performance prediction was presented.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2020.11a
• /
• pp.59-60
• /
• 2020

Large fires continue to spread throughout the building, including the fire in Uijeongbu in 2015, the fire in Jecheon in 2017, and the fire in Miryang in 2018. According to the above fire case investigation, major problems were the fire resistance performance of compartment members such as fire doors, the fire spread due to damage to exterior wall openings, and smoke spread through vertical openings. However, in South Korea, only specification design is implemented for buildings that are not subject to performance design. In addition, the analysis of the fire resistance performance standards of building members in the specification design showed that fire doors were not specified in detail for 60 minutes of insulation performance and 60 minutes of fire resistance performance of E/V doors, limiting the prevention of fire spread. Therefore, the purpose of this research is to prepare measures to prevent the spread of fire by presenting simple transplants for calculating the required fire time according to the architectural design conditions for the performance design of the components of the fire room according to the purpose of use of the front of the building.