• Proceedings of the KSME Conference
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• 2005.11a
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• pp.106.1-106.1
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• 2005

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.9
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• pp.1238-1247
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• 2003

Simplified thermodynamic analysis of high pressure 4-stage reciprocating compressors with 4 inter-coolers has been investigated to predict a behavior of a compressor system for NGV(natural gas vehicles). A computer program has been developed to predict and estimate the performance of high pressure 4-stage reciprocating compressor system. Thermodynamic properties of compressed natural gas(CNG) were calculated by ideal gas theory and compression cycle was assumed as reversible adiabatic compression and expansion processes, and isobaric intake and discharge processes. Comparison between results predicted by calculation model and measured by experimental tests is presented.

• Journal of the Korea Convergence Society
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• v.11 no.11
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• pp.443-450
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• 2020

The purpose of this study was to examine the inter-rater and intra-rater reliability of the oral mucosa pressure ulcer classification system based on the photographs. The study consisted of two stages; development and evaluation. In the developmental stage, 9 photographs of 82 were selected. In the evaluation stage, a total of 49 participants were invited web-based survey by e-mail. Cohen's weighted kappa and Krippendorff's alpha were used to define the inter-rater reliability. Nine photographs consisted of two, three, three, and one in normal, stage 1, stage 2, and stomatitis, respectively. The inter-rater reliabilities of wound care nurse specialist, intensive care nurse specialist, and dentist groups were 0.75, 0.70, and 0.78, respectively. The intra-rater reliability was 0.73. The inter-rater and intra-rater reliabilities of the oral mucosa pressure ulcer classification system showed substantially good agreement.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1467-1469
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• 2007

We report on the effect of ambient gas on the OLED degradation. The operating voltage and quantum efficiency increases when the device is exposed to the atmospheric gas and then returns to the initial level of the device in vacuum when the atmospheric gas is evacuated. These changes in the OLED performance can be attributed to the ambient gas pressure.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.5
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• pp.57-64
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• 2010

A performance test of inter propellant seal for a 75 ton class turbopump is conducted using water to evaluate leakage and endurance performance. Each part of fuel pump side and oxidizer pump side for a prototype inter propellant seal has been tested for verifying endurance performance during total accumulated test time 2,100 sec in water. The fuel pump side part with one-stage seal of carbon floating ring shows average leakage rate 13.7 gram/sec under average seal differential pressure 9.4 bar. On the other hand, the oxidizer pump side part with two-stage seal assembly of carbon floating rings shows average leakage rate 7.3 gram/sec under average seal differential pressure 9.5 bar. After the endurance performance test, the inter propellant seal shows good physical condition. A leakage performance test of the inter propellant seal for cryogenic environment will be performed using LN2 in the near future.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.47-53
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• 2010

A performance test of a 75 ton class turbopump inter propellant seal is conducted using water to evaluate leakage and endurance performance. Each fuel pump side part and oxidizer pump side part of a prototype inter propellant seal has been tested for verifying endurance performance during total accumulated test time 2,100 sec in water. The fuel pump side part with 1 stage carbon floating ring seal shows average leakage rate 13.7 gram/sec under average seal differential pressure 9.4 bar. On the other hand, the LOx pump side part with 2 stage carbon floating ring seal shows average leakage rate 7.3 gram/sec under average seal differential pressure 9.5 bar. After the endurance performance test, the inter propellant seal shows good physical condition. A cryogenic leakage performance test of the inter propellant seal will be performed using LN2 in the near future.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.6
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• pp.703-714
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• 2010

This paper proposes an approach for staged finite element modeling with coupled seepage and stress analysis. The stage modeling is based on the predefined inter-relationship between the base model and the unit stage models. A unit stage constitutes a complete finite element model, of which the geometries and attributes are subject to changes from stage to stage. The seepage analysis precedes the mechanical stress analysis at every stage. Division of the wet and dry zone and the pore pressures are evaluated from the seepage analysis and used in determining input data for the stress analysis. The results of the stress analysis may also be associated with the pore water pressures. For consolidation analysis, the pore pressure and the displacement variables are mixed in a coupled matrix equation. The time marching solution produces the dissipation of excess pore pressure and variation of stresses with passage of time. For undrained analysis, the excess pore pressures are computed from the stress increment due to loading applied in the unit stage and are used in revising the hydraulic head. The solution results of a unit stage are inherited and accumulated to the subsequent stages through the relationship of the base model and the individual unit stages. Implementation of the proposed approach is outlined on the basis of the core procedures, and numerical examples are presented for demonstration of its application.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.119-124
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• 2000

The 3-stage centrifugal compressor is used in order to measure the noise spectra of compressor, and analyze the results. Two cases are investigated for compressor noise components. Case I includes total system such as compressor, inter-cooler, motor, and Case II excludes cooling system. BPF tonal noise is important in compressor, and cooling system including inter-cooler contributes to broadband noise. Also, motor, gear box, and motor cooling fan are the second contributions to total compressor noise. Centrifugal compressor flow-field is calculated using two-dimensional grid and Navier-Stokes equations. Static pressure increases, and total pressure decreases, as air passes through the compressor components.

• Journal of Surface Science and Engineering
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• v.44 no.3
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• pp.75-81
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• 2011

Growth behaviors of iron-nitride on S45C steels at low pressure gas nitriding were examined. Surfaces of the steels covered with fine and porous oxide during the pre-oxidation using $N_2O$ gas. Well faceted particles connected with them were observed after 1 min nitriding. They grew steadily and filled inter-pores during additional nitriding process. From the X-ray diffraction analysis, ${\gamma}'$-iron nitride was dominantly formed at the initial stage but the amount of ${\varepsilon}$-iron nitride was rapidly increased as nitriding treatment time. The porous layer was formed on the particles and thickened up to half of nitride layer after 60 min nitriding. The observed growth behaviors were discussed in internal stress related with volume expansion involved in transforming from iron to iron-nitrides.

• Journal of Korean Clinical Nursing Research
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• v.18 no.1
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• pp.29-38
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• 2012

Purpose: The purpose of this study was to examine the accuracy of general nurses' assessments of pressure ulcers in hospitalized patients. Methods: A total of 129 nursing records of assessments on pressure ulcers were analyzed. Assessment records of pressure ulcers by general nurses were compared to those by Wound, Ostomy, Continence Nurses (WOCN) on the same pressure ulcers. A WOCN of a nursing unit was a nurse certified by the hospital after completion of a formal WOCN course and passing a cyber education course, both offered by the hospital. The formal WOCN course was taught by an internationally certified WOCN. The inter-rater reliability among WOCNs was 98.2%. General nurses in this study did not receive a structured pressure ulcer education. Results: The accuracy for nursing assessment of pressure ulcers by general nurses compared to WOCNs' were evaluated in various ways and resulted in as follows; the existence of pressure ulcer 91.4%, site of pressure ulcer 85.3%, stage of pressure ulcer 85.3%, Braden scale 36.3%, size of pressure ulcer 51.9~64.3%, details of pressure ulcer 0~100%. Conclusion: The structured education about pressure ulcer assessment is important to enhance the accuracy of pressure ulcer assessment of hospitalized patients by general nurses.