• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.7
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• pp.674-679
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• 2000

The Sirocco fan performance and its three-dimensional flow characteristics were numerically predicted by STAR-CD software. Turbulent flow computations were performed using approximately 500,000 mesh points, and the performance results of two computational methods, transient analysis and quasi-static analysis were compared with experimental data. At present, our attention was focused on localizing the three-dimensional flow characteristics of the Sirocco fin, especially the structure of the secondary flow in the scroll and the through-flow characteristics of the Sirocco fan blades. Also, for an optimization, the scroll passage was tilted with 10 degrees to change the flow characteristics and improve the performance of the Sirocco fan.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.837-843
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• 1998

This paper presents the thermomechanical and fracture mechanics evaluation procedure of thermal striping damage on the secondary piping of LMFR using Green's function method and standard FEM. The thermohydraulic loading conditions used in the present analysis are simplified sinusoidal thermal loads and the random type data thermal load. The thermomechainical fatigue damage was evaluated according to ASME code subsectionNH. The analysis results of fatigue for the sinusoidal and random load cases show that fatigue failure would occur at a geometrically discontinuous location during 90,000 hours of operation The fracture mechanics analysis showed that the crack would be initiated at an early stage of the operation. The fatigue crack was evaluated to propagate up to 5 ㎜ along the thickness direction during the first 944 and 1083 hours of operation for the sinusoidal and the random loading cases, respectively.

• Child Health Nursing Research
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• v.30 no.2
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• pp.108-117
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• 2024

Purpose: This study investigated the relationship between allergic diseases, general anxiety disorder, and depressive symptoms among Korean adolescents. Methods: A secondary analysis was conducted on the findings of the 18th Korea Youth Risk Behavior Survey (2022). The study included 51,850 adolescents and analyzed the relationships among allergic diseases, general anxiety disorder, and depressive symptoms using complex samples logistic regression analysis. Results: Among the Korean adolescents, 12.7% experienced general anxiety disorder, while 28.7% experienced depressive symptoms. The prevalence of allergic diseases was 5.7% for asthma, 36.3% for allergic rhinitis, and 22.2% for atopic dermatitis. General anxiety disorder was associated with asthma and allergic rhinitis but not atopic dermatitis. Depressive symptoms were associated asthma, allergic rhinitis, and atopic dermatitis. Conclusion: Examining the correlation among allergic diseases, general anxiety disorder, and depressive symptoms in adolescents underscores the need for implementing suitable strategies. Moreover, when addressing general anxiety disorder and depressive symptoms in adolescents, it becomes crucial to consider the presence of allergic diseases.

• Research in Community and Public Health Nursing
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• v.29 no.4
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• pp.520-529
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• 2018

Purpose: The purpose of this study is to identify factors influencing activities-specific balance confidence in community-dwelling older adults. Methods: This is secondary analysis of data from an intervention study for improving cognitive function. The data were collected from March 2 to September 30, 2017 at a senior center. Data of 131 older adults were included for this secondary analysis, and were analyzed by using t-test, ANOVA, and multiple regression. Results: The mean score of activities-specific balance confidence is 65.08 out of a possible range of 0-100. The significant factors affecting activities-specific balance confidence among old adults include 'more than 85 years old', 'waist circumference', 'depressive symptoms', 'activity restriction due to fear of falling', and 'self-rated health' which explained 52.8% of the variance. Conclusion: The study results indicate that psychologic factors as well as physical condition should be considered for interventions to increase activities-specific balance confidence.

• Journal of Korean Biological Nursing Science
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• v.26 no.1
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• pp.49-59
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• 2024

Purpose: This study was conducted to identify factors associated with high-risk drinking in Korean men. Methods: This study was a secondary analysis using data from the Korea National Health and Nutrition Examination Survey (KNHANES VIII-2), 2020. Data were downloaded from the KNHANES website. The subjects of this study were 1,653 alcohol-drinking men between 19 and 64 years of age. Data were analyzed using the Rao-Scott chi-square test and complex sample logistic regression statistics. Results: The high-risk drinking rate among alcohol-drinking men was 27.1%. High-risk drinking was more common in men who smoked (odds ratio [OR] = 2.11, p < .001), men with a middle school education or lower (OR = 1.91, p = .016), men who lived with a spouse (OR = 1.61, p = .025), men who slept less than 6 hours on weekends (OR = 1.51, p = .016), and men who perceived stress (OR = 1.30, p = .044), while it was lower in men who were underweight (OR = 0.19, p = .006). Conclusion: To reduce the rate of high-risk drinking, it is necessary to provide an intervention that considers factors associated with high-risk drinking among men. In particular, smoking was the most important factor associated with high-risk drinking, implying that the integrated management of drinking and smoking is necessary to reduce high-risk drinking.

• Corrosion Science and Technology
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• v.15 no.3
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• pp.135-140
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• 2016

Piping and equipment are degraded by flow-accelerated corrosion (FAC) in nuclear power plants. FAC causes numerous problems and nuclear utilities maintain programs to control FAC. The key parameters influencing FAC are hydrodynamic conditions, water chemistry, and effect of materials. Recently, a nuclear utility has planned slight power uprates in Korea. Operating conditions need to be changed in the secondary system according to power uprates. This study analyzed the effect of wall-thinning caused by power uprates. The change of operation data in the secondary cycle is reviewed, and wall-thinning rates are analyzed in the main lines. As a result, two phase (mixture of water and steam) lines have a greater impact than a water line under power uprate conditions. Also, the quality of steam is the most important factor for FAC in two phase lines.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.134-140
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• 2007

Nonlinear parabolized stability equations for compressible flow in general curvilinear coordinate system are derived to deal with a broad range of transition prediction problems on complex geometry. A highly accurate finite difference PSE code has been developed using an implicit marching procedure. Blasius flow is tested. The results of the present computation show good agreement with DNS data. Nonlinear interaction can make the T-S fundamental wave more unstable and the onset of its amplitude decay is shifted downstream relative to linear case. For nonlinear calculations, rather small difference in initial amplitude can produce large change during nonlinear region. Compressible secondary instability at Mach number 1.6 is also simulated and showed that 1.1% initial amplitude for primary mode is enough to trigger the secondary growth.

• Journal of Food Hygiene and Safety
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• v.9 no.1
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• pp.43-48
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• 1994

Instrumental determination was performed for the analysis of residues of ethylene oxide(EO), ethylene chlorohydrin(ECH) and ethylene glycol(EG) in white ginseng powders which were deaerated for 30 min after EO fumigation. Gas chromatographic data showed that EO residues were 570 ppm in the immediate samples after deaeration and 170 ppm in the stored ones for 8 days at 30$\pm$1$^{\circ}C$, respectively, showing a decreasing tendency with elapsed time. On the other hand, ECH and EG residues in samples as the secondary products of EO were 17, 650 ppm and 727 ppm stored for one month, and 9, 595 ppm and 221 ppm stored for 3 months, respectively.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.661-666
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• 2000

Near-wake flow field of a circular cylinder is studied by means of a cinematic PIV system with high sampling rate and large internal memory block. Experiments are conducted in a closed-cycle water tunnel system and a cross-correlation algorithm in conjunction with FFT (Fast Fourier Transform) analysis and an offset correlation technique is used for vector processing. With the help of very high sampling frequency compared to the shedding frequency, it is possible to obtain phase-averaged information of the three-dimensional wake, even though the shedding is not forced but natural. Phase-locked vortical structures observed simultaneously from the spanwise and cross-stream planes are displayed in the wake-transition regime where fine-scale secondary vortices have a spanwise wavelength or around one diameter. Spatial relations and temporal evolutions of the primary Karman vortex and the secondary vortex are also discussed schematically.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.1115-1120
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• 2017

In this paper, we apply the LMMSE(: Linear Minimum Mean Square Error) algorithm to overcome the Doppler effect according to the UAV(: Unmanned Aerial Vehicle) velocity in multipath fading channel environment. Simulation results show that the performance difference depends on the pilot arrangement and pattern, and we confirmed that the frame structure proposed in this paper can provide a stable secondary link for high speed UAV system.