• Journal of computational fluids engineering
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• v.21 no.4
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• pp.61-70
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• 2016

Dong-tan Station, shared by high-speed railway and urban express railway, is a very complicated underground station having 6 tracks together with barrier and shafts between them, therefore it seems very hard to investigate the aerodynamic effects including the pressure variation and train gust in the station when a high-speed train runs through it. In this study, the aerodynamic effects on the structures and platform passengers when a high-speed train runs through an underground station have been studied using Computational Fluid Dynamics. STAR-CCM+ has been employed for numerical simulation based on Navier-Stokes equation and 2-equation turbulence model and moving mesh scheme supported by STAR-CCM+ has also been used to represent the relative motion between a train and station. Based on the simulation results, the unsteady flow fields in the underground station induced by the high-speed train have been analyzed and the pressures on the PSDs and pressure variation at the platform have quantitatively assessed.

• Journal of computational fluids engineering
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• v.17 no.1
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• pp.36-43
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• 2012

When a high-speed train passes an underground station, large pressure waves are generated due to the piston effect. These pressure waves can cause the problems of vibration and noise as well as the ear discomfort of passengers at the underground station. This work numerically analyzed the pressure wave generation and propagation in an high-speed railway underground station, and the optimal location for vent shafts was studied to improve the passenger comfort by reducing the magnitude of the pressure wave and its rate of change. The evolution of pressure field in the underground station was calculated using a CFD(Computational Fluid Dynamics) software(Fluent), where the axis-symmetric two-dimensional model verified by Wu was used. And this study is applied to modelling of the underground station and the tunnel from Daegok station A-line of GTX(Great Train Express). From the result, we can have a conclusion that the role of vent shafts respectively were different according to the position in and out the underground station. Also Vent shaft in the underground station widely reduced pressure magnitude. And vent shaft out underground station reduced initial pressure peak value. Double vent shafts installed at tunnel toward station entrance and inside of the tunnel are the most efficient to reduce pressure. and pressure reduction increases according to the number of vent shaft.

• Journal of the Korean Society for Railway
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• v.16 no.6
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• pp.454-459
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• 2013

Pressure waves are generated and propagate in a tunnel when train enters tunnel high speed. A compression wave due to the entry of train head propagates along the tunnel and is reflected at tunnel exit as an expansion wave. An expansion wave due to the entry of the train tail propagates along the tunnel and is reflected at tunnel exit as a compression wave. These pressure waves are repeatedly propagated and reflected at the tunnel entrance and exit. Severe pressure changes causes ear-discomfort for passengers in the cabin and micro pressure waves around the tunnel exit. It is necessary to analyze the transient pressure phenomena in tunnels qualitatively and quantitatively, because pressure change rate is considered as one of the major design parameters for optimal tunnel cross sectional area and repeated fatigue force on car body. In this study, we developed a characteristics method based on a fixed mesh system and boundary conditions for crossing trains and analyzed this system using an X-t diagram. The results of the simulation show that offsetting of pressure waves occurs for special entry conditions of a crossing train.

• Journal of the Korean Society of School Health
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• v.22 no.1
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• pp.107-118
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• 2009

Purpose: The purpose of this study was to investigate usage of earplones, PCPs, and to give the basic data for adolescent's hearing health education. The study was a descriptive research about three factors affecting hearing loss; the knowledge and attitude about noise, the perception of hearing loss. Method: For research purposes, we conducted a questionnaire survey of 1,480 high school students in Suwon, from 27 October 2007 to 31 2007. Result: Most of the subjets used PCPs for 3-5 years, the average time of using earphones per day was 1-3 hours, awake hearing acuity decrease after using is the hearing acuity became worse some, PCPs type is MP3, use place house, listening contents ballade, disorder condition experience after using if the ear it is sick. The average of concern about hearing scored the highest 3.01${\pm}$0.54. The average of perceived susceptibility scored 3.04${\pm}$0.63 and the average of knowledge about noise scored 2.76${\pm}$0.46. The average of total knowledge and attitude about noise scored 2.93${\pm}$0.52. The average of discomfort of hearing loss(2.20${\pm}$0.63) scored higher than that fear of hearing loss(1.66${\pm}$0.30). The average of total perception of hearing loss scored 2.12${\pm}$0.67. Conclusion: At least in this study are shown in the youth earphone, PCPs used as a spare because of the seriousness of the issue, so as a result of these problems related to hearing about the youth campaign, through advertising or seriousness of the young people need them. In addition, countries also need to create policies and the support for health education, especially during the regular curriculum subjects on subjects that include teenagers in the earphone, PCPs due to problems with spare on the contents of the reservoir. The severity of hearing loss young people, prevention of hearing to protect the youth.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.14 no.1
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• pp.62-71
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• 2007

Purpose: This study was done to compare sleep patterns, factors of sleep disturbance and sleep enhancement behaviors between sleep disturbance and non-sleep disturbance elderly patients. Method: The participants were 117 patients over 65 years old who were hospitalized at 5 general hospitals in Seoul. There were 83 patients in the good sleeper group and 34 in the poor sleeper group. The survey questionnaires included questions on general characteristics, sleep patterns, sleep disturbing factors, and sleep enhancement behaviors of the patients. Results: For sleep patterns and environmental factors of sleep disturbance, the poor sleepers was significantly higher than that of the good sleepers. Significant differences between good sleepers and poor sleepers were also found on the following variables: Environmental factors of sleep disturbance -'Sound of other patient's or care-giver's', 'Discomfort of bed, linen, pillow and patient's gown', 'Light in the room', 'Emergency situations', 'Temperature of patients rooms too hot or too cold'. The significant physical factor of sleep disturbance was 'Hard to breath even without moving' and for sleep enhancement behaviors: 'Use of ear plugs or eye covers' Conclusion: Consequently it is necessary to develop positive and differentiated programs for sleep enhancement for the inactive and poor sleeper among the elderly patients.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.2
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• pp.209-220
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• 2021

The noise is defined as unwanted sound that causes discomfort and physical changes. This study was conducted to evaluate intensity of noise in the pediatric dental clinic and to investigate noise environment of a pediatric dentist. Human ear shaped microphone and mobile noise level meter were used for recording noise and calculating intensity of noise. By recording according to the method specified by Korea Occupational Safety and Health Agency (KOSHA) of Korea Ministry of labor and employment, the following results were obtained. For 16 experimental days, 8 hour time weighted average (8hr-TWA) was 49.33 dBA (A-weighted deci-Bell) on daily average with maximum 58.54 dBA and minimum 33.97 dBA. And Dose was 0.49% on daily average with maximum 1.28%, minimum 0.04%. These values are less than criteria of KOSHA standard (85 dBA, 100%). Comparing the highest noise level for each patient, pulp therapy group and Frankel grade I group were the highest. The intensity of dental noise of pediatric dental clinic didn't meet standard of KOSHA. It is necessary to re-evaluate noise environment by establishing new standards considering environment of pediatric dental clinic.

• Research in Community and Public Health Nursing
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• v.12 no.1
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• pp.125-141
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• 2001

The purpose of this study was to investigate the factors affecting hearing loss in adolescent's use of PCPs, and to give the basic data for adolescent's hearing conservation program development and prevention education against their hearing loss. This study was a descriptive research about three factors affecting hearing loss; the knowledge and attitude about noise, the perception of hearing loss and the hearing threshold. The subjects of this study were 383 students in two general high schools and two vocational high schools in Teagu. They have been using PCPs but with no current or past ear disease. This study was carried out from Sep. 1. 2000 to Oct. 24, 2000. The instrument used for the knowledge and attitude about noise was a questionnaire developed by Rhee. Kyung Yong and Yi. Kwan Hyung(1996). The instrument used for the perception of hearing loss was a Smith Hearing Screening Questionnaire. A Belton Model 112 Audiometer. air-conduction hearing test instrument. was used for the hearing threshold. Data was analysed by a SPSS/Win 10.0 program with frequency. percentage, t-test. ANOVA and pearson correlation. The results of this study were as follows; 1. The average of concern about hearing scored the highest $3.66{\pm}0.70$. The average of perceived susceptibility scored $2.64{\pm}0.85$ and the average of knowledge about noise scored $2.13{\pm}0.56$. The average of total knowledge and attitude about noise scored $2.82{\pm}0.46$. The average of discomfort of hearing loss($2.51{\pm}0.81$) scored higher than that fear of hearing loss($1.35{\pm}0.53$). The average of total perception of hearing loss scored $1.93{\pm}0.59$. The hearing threshold of the subjects scored the highest at 500Hz(Lt. $23.21{\pm}6.62$, Rt. $23.39{\pm}7.02$) and scored higher in order of 1000Hz, 2000Hz, 4000Hz and 8000Hz. 2. The knowledge and attitude about noise and the perception of hearing loss were both affected only by one important characteristic, which was general and vocational high schools. The knowledge and attitude about noise raked (t=5.258, p=0.000), and perception of hearing loss raked(t=2.241. p=0.026). However. several other important characteristics also impacted significantly on the knowledge and attitudes about noise. They included grade (t = 1. 987. p=0.048), father's education(F=2.745. p=0.043), marks(F=3.157, p=0.044), drinking(t=2.307, p=0.022) and smoking(t=2.587, p=0.010). The left hearing threshold differed significantly by sex at 1000Hz(t=5.175, p<0.001) and 8000Hz (t=3.334, p<0.01). According to general and vocational high schools (p<0.001), at 500Hz (t=-5.056), 1000Hz (t=-5.253), 2000Hz (t=-4.905), 4000Hz (t=-4.704) and 8000Hz (t=-5.204) significant differences were also shown. Marks were significant at 1000Hz (F=3.824, p<0.05) and drinking was found to be significant at 500Hz(t=2.203, p<0.05). The right hearing threshold differed significantly by sex at l000Hz(t=5.557. p<0.001). 4000Hz(t=2.234. p<0.05) and 8000Hz (t=2.730. p<0.01). According to general and vocational high schools(p<0.001) at 500Hz (t=-4.730), 1000Hz(t=-6.271). 2000Hz (t=-4.573). 4000Hz(t=-3.554) and 8000Hz (t=-3.405) significant differences were also shown. Grades impacted at 500Hz(t=2.201. p<0.05) and 4000Hz(t=2.511. p<0.05), while marks were significant at l000Hz(F=4.1l5. p<0.05) and drinking was significant at 500Hz(t=2.333. p<0.05). 3. The left hearing threshold in accordance with use of PCPs differed significantly at 2000Hz(F=2.996. p=0.03l) according to volume level and at 8000Hz(F=2.197. p=0.022) according to duration${\times}$hours per day. The right hearing threshold differed significantly at l000Hz(F=3.075. p=0.028) according to volume level and at 8000Hz(F=2.925. p=0.034) according to duration. 4. The knowledge and attitudes about noise showed a light positive correlation with the perception of hearing loss. A positive correlation was shown. as stated previously in all Hz, between the left hearing threshold and the right hearing threshold, especially the highest correlation at 2000Hz(r=0.761. p=0.000). This study has shown that the factors related to adolescent's use of PCPs are important as they impact significantly an adolescent's hearing. These results then indicate that in future, when designing a hearing conservation program and prevention education this data should be considered.