• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.5
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• pp.615-622
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• 2000

Numerical simulation is performed with Denton's code to get pressure loss coefficients in wide range of reverse flow incidence(from -90 degree to +85 degree) for an axial compressor cascade. As a results, it is found that the pressure loss coefficient is increased with incidence and there exist critical incidence which corresponds to the maximum pressure loss coefficient. Pressure loss coefficient with bigger incidence than its critical value is decreased. The effect of increasing incidence in a cascade extremely reduce the mass flow rate by the large flow separation region. Consequently this effect reduce the portion of dynamic pressure in the total pressure loss and beyond the critical incidence the pressure loss coefficient decrease.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2591-2596
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• 2007

The effect of incidence angle on the three-dimensional flow and aerodynamic loss in the downstream region of a high-turning turbine rotor blade has been investigated with a straight miniature five-hole probe. The incidence angle is changed to be +10, +5, 0, -10, -20, -30 and -40 degrees. The results show that the positive incidence reinforces the three-dimensional vortical flows within the turbine passage including the passage vortex, but the negative incidence weaken them significantly. A small increment in the positive incidence angle results in a remarkable aerodynamic loss increase, while increasing the incidence angle in the negative range leads to a very small change in the aerodynamic loss.

• The KSFM Journal of Fluid Machinery
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• v.2 no.4 s.5
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• pp.48-56
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• 1999

For the study on loss coefficients of turbine cascade with variation of incidence angle, the wind-tunnel tests were performed under the ranges in velocity of 10 m/s, 15 m/s, 20 m/s and incidence angles from $-20^{\circ}\;to\;20^{\circ}$ by intervals of $5^{\circ}$. Comparing our results with Soderberg's prediction, differences in loss coefficient were $2.5\%\;and\;2.8\%$ each for 10 m/s and 15 m/s. A large disagreement of $30.3\%$ was showed at 20 m/s freestream velocity. The comparisons of these test results with Ainley's prediction showed an $8\%$ difference in the case of 20 m/s freestream velocity. Test results were approximately comparable with Ainley's loss prediction's in incidence angles. Generally, averaged total pressure loss seemed to be decreased as Reynolds number increased. The total pressure loss coefficients were increased parabolically, as incidence angles were increased negatively and positively from $0^{\circ}$, in all speed ranges. At the far low freestream velocities, minimum loss accurred between $-5^{\circ}\;and\;+5^{\circ}$. But this minimum range narrowed the location of this range by shifting to the direction of the angle as freestream velocity was increased.

• The Journal of Korean Society for School & Community Health Education
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• v.14 no.2
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• pp.93-112
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• 2013

Objectives: This study was conducted to investigate the incidence rate of noise-induced hearing loss (NIHL) in Korean youths using the National Health Insurance Data Methods: We obtained the case of NIHL with the National Health Insurance Data and calculated the incidence rate of NIHL after classifying them by year (from 2005 through 2008), age, gender, birth cohort. Results: The age-adjusted incidence rate by year of NIHL per 100,000 population increased by 40.6% from 13.8 persons in 2005 to 19.4 persons in 2008, which showed a increasing trend every year. In particular, the incidence rate per 100,000 population among the adolescents (15-19 years of age) shot up by 78.2% from 8.7 persons in 2005 to 15.5 persons in 2008. According to the incidence rate by birth cohort of NIHL, the birth cohorts showed the gradually increase in incidence rate as time passed by. Adolescents in early 20s (20-24 years of age) had a higher incidence rate than teenage and men had a higher incidence rate than women. Conclusions: The results suggest that incidence rate of NIHL in Korean youths has rapidly increased among adolescents. Therefore, it is required to educate adolescents about the risk of hearing loss due to noise, establish program to prevent NIHL among adolescents and provide them with health education on hearing loss prevention.

• The KSFM Journal of Fluid Machinery
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• v.13 no.2
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• pp.41-47
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• 2010

The effect of incidence angle on the three-dimensional flow and aerodynamic loss in the tip leakage flow region downstream of a turbine rotor cascade has been investigated for two tip gap-to-chord ratios of h/c=0.0% (no tip gap) and 2.0%. The incidence angle is changed to be $i=-10^{\circ}$, $0^{\circ}$, and $5^{\circ}$. The results show that for $i=5^{\circ}$, secondary flows including the passage vortex are intensified noticeably, and there is a strong interaction between the passage and tip leakage vortices. For $i=-10^{\circ}$, however, the passage vortex is weakened significantly, so that there exists only a strong leakage-jet-like secondary flows near the casing wall. For h/c=0.0% and 2.0%, aerodynamic loss tends to increase with increasing i from $-10^{\circ}$ to $5^{\circ}$. A small increment of i in its positive incidence range results in a remarkable aerodynamic loss increase, while increasing i in the negative incidence range leads to a small change in the aerodynamic loss generation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.1052-1055
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• 2004

This paper introduces an experimental study on the grazing incidence sound absorptions for duct silencers filed with a glass wool and consisted of a perforated panel. The experimental results are discussed in comparison with the normal incidence sound absorption. And also the transmission loss for duct silencers are measured and compared with the sound absorption performances. From the experimental results, it is shown that the resonance frequency bandwidth on the transmission loss and sound absorption coefficient for duct silencers has a good agreement.

• Journal of the Korean Society of Physical Medicine
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• v.18 no.4
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• pp.37-45
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• 2023

PURPOSE: The coexistence of age-related skeletal muscle mass loss and obesity poses a substantial health risk for individuals because it combines the detrimental effects of muscle mass reduction associated with aging and the health complications from obesity. This study aimed to identify the incidence rate and key influencing elements among Korean men in their thirties. METHODS: A cross-sectional study involving 934 male participants was performed using complex sampling analysis. Various influencing elements were investigated, including age, height, weight, body mass index, waist circumference, skeletal muscle mass index, smoking and drinking behaviors, systolic and diastolic blood pressure, fasting glucose levels, triglyceride, and cholesterol levels. RESULTS: The incidence rate was 2.90%. The key influencing elements were age, height, weight, body mass index, waist circumference, skeletal muscle index, systolic blood pressure, fasting glucose, triglyceride, and total cholesterol (p < .05). CONCLUSION: This study identified the incidence rate and key influencing element for CALSMO among Korean younger community-dwelling men.

• Journal of Veterinary Clinics
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• v.25 no.2
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• pp.85-89
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• 2008

This study assessed the incidence of embryo and fetal loss following early pregnancy diagnosis using ultrasonography in dairy cows. A positive pregnancy was a recognition of the vesicle, embryo or fetus by ultrasonography. Seven hundreds and two pregnancies determined by ultrasonography following artificial insemination were divided into three groups according to the number of days diagnosed pregnant: early A group (27 to 40 days, n = 143), early B group (41 to 50 days, n = 172), or standard group (51 to 70 days, n = 387). Following a positive pregnancy diagnosis, embryo or fetal loss included all cows with observed abortions and cows found open after the positive pregnancy diagnosis. The incidence rate of embryo or fetal loss within 7 days after pregnancy diagnosis was 1.4, 0.6 and 0.3% for the early A, early B, and standard groups, respectively (P>0.05). The incidence of the embryo or fetal loss during 8 to 30 days after pregnancy diagnosis did not differ (P>0.05) among the early A (0%), early B (1.2%), and standard groups (1.0%). Furthermore, the cumulative incidence of the embryo or fetal loss before calving did not differ (P>0.05) among the early A (9.8%), early B (9.3%), and standard groups (5.9%). These results indicate that early pregnancy diagnosis using ultrasonography does not increase the risk of embryo and fetal loss compared with that of routine pregnancy diagnosis in dairy cows.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.2
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• pp.113-120
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• 2017

PURPOSE: The purpose of this study was to investigate the effect of a physical therapy-based tailored exercise program on pain, accident incidence rates, the number of work days lost, and economical loss cost for workers in an automobile parts manufacturing company. METHODS: A total of 530 workers with musculoskeletal symptoms were given a physical therapy-based tailored exercise program twice a week, for one hour a day. This exercise program consisted of movement pattern correction, muscle stretching and strengthening, and postural correction exercises, according to principles of movement impairment syndromes and medical training therapy. From 2011 to 2016, the lost days of work, accident incidence rates, and loss cost were examined. The pain measured by VAS (visual analogue scale) and the number of workers participating in the exercise program from 2014 to 2016 were also measured. The single subjects A-B design was applied and analyzed. RESULTS: After applying the exercise program, pain decreased and the number of workers participating in the program increased. Accident incidence rates, number of work days lost, and economical loss cost decreased. There was a significant correlation between the number of workers who received exercise therapy by year and accident incidence rates, lost days of work, and economical loss cost (p<.05). CONCLUSION: It is necessary to expand the physical therapy-based tailored exercise program to prevent musculoskeletal disorders because it has a positive effect on both workers and employers.

• Journal of Mechanical Science and Technology
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• v.14 no.4
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• pp.456-465
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• 2000

An experiment was conducted to investigate the aerodynamic losses of high pressure steam turbine nozzle (526A) subjected to a large range of incident angles ($-34^{\circ}\;to\;26^{\circ}$) and exit Mach numbers (0.6 and 1.15). Measurements included downstream Pitot probe traverses, upstream total pressure, and end wall static pressures. Flow visualization techniques such as shadowgraph and color oil flow visualization were performed to complement the measured data. When the exit Mach number for nozzles increased from 0.9 to 1.1 the total pressure loss coefficient increased by a factor of 7 as compared to the total pressure losses measured at subsonic conditions ($M_2<0.9$). For the range of incidence tested, the effect of flow incidence on the total pressure losses is less pronounced. Based on the shadowgraphs taken during the experiment, it' s believed that the large increase in losses at transonic conditions is due to strong shock/ boundary layer interaction that may lead to flow separation on the blade suction surface.