• Journal of Korean Academy of Fundamentals of Nursing
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• v.13 no.2
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• pp.190-199
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• 2006

Purpose: To provide basic data and to identify the risk of pressure ulcers among neurological patients in ICU. Method: The participants in the study were on 78 neurological patients in the ICU of 3 hospitals. Data were collected every other day from 24 hours after admission, for up to 40 days or until discharge. The total period of data collection was 3 months. The risk assessment scales used for pressure ulcer were the Cubbin & Jackson(1991) scale and the National Pressure Ulcer Advisory Panel(1989) skin assessment tool. Results: There was a significant relationship between having a pressure ulcers and weight, skin condition, mental status, respiration, hygiene and hemodynamic status compared to not having a pressure ulcer. The incidence rate of the pressure ulcer was 28.2%(n=22). Of these patients the mean number of hospitalization days until pressure ulcer development was 5.2 days. The most common pressure ulcer site was the coccyx(39.3%). Based on a cut-off point of 24, 9 patients with risk scores <24 on admission also showed risk score for development of pressure ulcers, 10 patients with pressure ulcer scores ${\geq}24$ were older, hospitalized for a longer time, had low serum albumin, low hemoglobin, diabetes mellitus and surgery. Conclusion: In order to make the Cubbin & Jackson risk assessment scales more useful, there is a need to determine the reliability of the upper cut-off point 24. The result also showed a need to assess other risk factors and for early identification of at-risk patients in order to provide preventive care from admission to discharge.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.259-264
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• 2000

The functions of the plug valve are the control of flow rate as well closing and opening pipe lines. Analyses on the flow characteristics in plug valve port are required to improve the performance and safety at severe operating conditions such as high-pressure and high-temperature. In this study, numerical analyses are carried out with varying the opening rate (fraction of the full open to close) of the valve and the shapes of valve Uk: straight, convex, concave and mixed shapes. The parameters influencing the flow characteristics in the valve are the discharge coefficient( $C_v$) and the resistance coefficient( K). Therefore, the distributions of static pressure, velocity vector and stream lines are investigated, and $C_v$ and K are calculated in each opening rate and shape. In case of full open, the static pressure passed through the valve port has almost been recovered. However, in case of other opening rates, the pressure does not permanently regained due to pressure drop leading to loss. This phenomenon in each shape of the valve shows the different behaviors. Calculation results show that the mixed shape has the best flow attribute.

• Journal of the Korean Chemical Society
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• v.34 no.5
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• pp.396-403
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• 1990

We describe how to design and construct a LPCVD (Low Pressure Chemical Vapor Deposition) apparatus which can be applicable to the study of reaction mechanism in general CVD experiments. With this apparatus we have attempted to make diamond like carbon films on the p-type (111) Si wafer from (H$_2$ ＋ CH$_4$) gas mixtures. Two different methods have been tried to get products. (1)The experiment was carried out in the reactor with two different inlet gas tubes. One coated with phosphoric acid was used for supplying microwave discharged hydrogen gas stream, and methane has been passed through the other tube without the microwave discharge. In this method we got only amorphous carbon cluster products. (2) The gas mixture (H$_2$ ＋ CH$_4$) has been passed through the discharge tube with the Si wafer located in and/or near the microwave plasma. In this case diamond-like carbon products could be obtained.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.603-609
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• 2015

Dry air is an excellent alternative to $SF_6$ gas and is used as an insulation gas in Eco-friendly Gas Insulated Switchgears (EGISs), which has gained popularity in industry. Solid insulators in EGIS play an important role in electrical insulation. On the other hand, surface discharge can occur easily when solid insulators are used. This paper explored the surface discharge characteristics on the structure of three-layered laminated solid insulators to elevate the flashover voltage. A laminated solid insulator was inserted after the quasi-uniform electric field was formed in the test chamber. Dry air was then injected to set the internal pressure to 1 ~ 6 atm, and the AC voltage was applied. When identical solid insulators were stacked, the surface discharge characteristics were similar to those of a single solid insulator. On the other hand, the flashover voltage rose when the middle part was thicker and had lower permittivity than the top and bottom parts in the laminated solid insulator. Based on experimental results, when stacking a solid insulator in three layers, the middle part of the solid insulator should be at least four times as thick as the top and bottom parts and have lower permittivity than the others. In addition, the flashover voltage increased with increasing gas pressure on the surface of the laminated solid insulator due to the gas effect. This study may allow insulation design engineers to have useful information when using dry air for the insulation gas where the surface discharge can occur.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.312-312
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• 2011

In SiH4/H2 discharge for growth process of hydrogenated amorphous silicon (a-Si:H), silane polymers, produced by SiH2 + Sin-1H2n ${\rightarrow}$ SinH2n+2, have no reactivity on the film-growing surface. However, under the SiH2 rich condition, high silane reactive species (HSRS) can be produced by electron collision to silane polymers. HSRS, having relatively strong reactivity on the surface, can react with dangling bond and form Si-H2 networks which have a close correlation with photo-induced degradation of a-Si:H thin film solar cell [1]. To find contributions of suggested several external plasma conditions (pressure, frequency and ratio of mixture gas) [2,3] to suppressing productions of HSRS, some plasma characteristics are studied by numerical methods. For this study, a zero-dimensional global model for SiH4/H2 discharge and a one-dimensional particle-in-cell Monte-Carlo-collision model (PIC-MCC) for pure SiH4 discharge have been developed. Densities of important reactive species of SiH4/H2 discharge are observed by means of the global model, dealing 30 species and 136 reactions, and electron energy probability functions (EEPFs) of pure SiH4 discharge are obtained from the PIC-MCC model, containing 5 charged species and 15 reactions. Using global model, SiH2/SiH3 values were calculated when pressure and driving frequency vary from 0.1 Torr to 10 Torr, from 13.56 MHz to 60 MHz respectively and when the portion of hydrogen changes. Due to the limitation of global model, frequency effects can be explained by PIC-MCC model. Through PIC-MCC model for pure SiH4, EEPFs are obtained in the specific range responsible for forming SiH2 and SiH3: from 8.75 eV to 9.47 eV [4]. Through densities of reactive species and EEPFs, polymerization reactions and production of HSRS are discussed.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.456-462
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• 2015

The objective of this study was to develop an advanced pump technology using tornado and axial pumping principles without priming water. The developed rotor type slurry pump consisted of an electric motor, driving shaft and coupling, a rotor, an impeller, suction and discharge pipes. For the clean water test, the experimental results are presented for the discharge flowrate, electric power input and vacuum pressure with the rotor design parameters as a function of the motor rpm. The slurry discharge characteristics with the solid concentration of the cement slurry was performed. As the rotor diameter and height increase, the discharge flowrate and electric power input increase while the vacuum pressure in the suction pipe decreases. The rotor thickness had no significant effect on the discharge flowrate and electric power input. Slurries with more than 18 % solid concentration, which is the development factor, can be pumped.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.5-9
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• 2002

In this paper, a relationship between AC discharge progress and the radiated electromagnetic waves was investigated by measuring electromagnetic waves using a biconical antenna and a spectrum analyzer at the atmospheric pressure in L$N_{2}$ . From the results of this study, according to the consideration of the mutual relation between frequency spectrum of the radiated electromagnetic waves and discharge progress, it was confirmed that detecting partial discharge and estimating discharge progress can be possible. It Is considered that these results obtained from this investigation may be used as the fundamental data for diagnosis and prediction of insulation on superconducting and cryogenic power equipments.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.2
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• pp.91-97
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• 2003

In addition to its strong oxidizing power, the ozone has definite advantages over other commercial oxidants, namely, no undesirable by- products or residues are formed. With growing interest in the improvement of the ozone production in the industrial fields, many types of ozonizer using the electrical discharges have been proposed for the higher efficiency and the higher Performance at atmospheric Pressure. Among them, a superposition of different type discharges has been proposed. Especially, since the improvement for the low efficiency of dc discharge and narrow gap of surface discharge is required, a do and an at voltage are applied to same reaction space (or volume) to increase energy density at the same space. An investigation was focused on the superposition with a dc (streamer) corona and 3 surface discharge. This paper describes the investigation results on fundamental ozone generation characteristics by this superimposed discharge.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.147-150
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• 2006

Vent ports are installed on the walls of closed compartments of a launch vehicle to control the pressure drop in the compartments. The ports can be modelled as an orifice, and the accurate prediction of the discharge coefficient of an orifice is essential for the design of vent ports. Experimental methods have been used to determine the discharge coefficients for various shapes of orifices, and extensive databases are available. Wind tunnel tests have been also done to evaluate the effect of interaction between venting outflow and freestream for limited conditions. The goal of the present research is to predict the discharge coefficient of an orifice using CFD and evaluate the accuracy of the method, especially for the orifices exposed to the external flow.

• Journal of the Korean Society of Industry Convergence
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• v.15 no.2
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• pp.49-54
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• 2012

With the improvement of industrial society, the high quality electrical energy, simplification of operation and maintenance, ensuring reliability and safety are being required. This paper reviews a basic data of the surface discharge characteristics for teflon resin in not only pure $N_2$, $N_2:O_2$ mixture gas and Dry-Air as being focused on environmentally friendly insulating Gas also $SF_6$. Used electrodes are Knife to Knife. With the changing distance of electrodes and pressure, we can find it, surface discharge voltages and surface dielectric strengths, respectively. Surface discharge Voltages of $N_2:O_2=80:20$ mixture gas are more higher than the $N_2:O_2$ Mixture gases.