• 한국유체기계학회 논문집
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• 제20권2호
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• pp.63-68
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• 2017

This paper predicts the rotordynamic force coefficients of tilting pad journal bearings (TPJBs) with ball-socket pivot and compares the predictions to the published test data obtained under load-between-pad (LBP) configuration. The present TPJB model considers the pivot stiffness calculated based on the Hertzian contact stress theory. Due to the compliance of the pivot, the predicted journal eccentricity agree well with the measured journal center trajectory for increasing static loads, while the early prediction without pivot model consideration underestimates it largely. The predicted pressure profile shows the significant pressure development even on the unloaded pads along the direction opposite to the loading direction. The predicted stiffness coefficients increase as the static load and the rotor speed increase. They agree excellently with test data from open literature. The predicted damping coefficients increase as the static load increases and the rotor speed decreases. The prediction underestimates the test data slightly. In general, the current predictive model including the pivot stiffness improves the accuracy of the rotordynamic performance predictions when compared to the previously published predictions.

• Journal of Korean Neurosurgical Society
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• 제65권5호
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• pp.751-757
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• 2022

Objective : Tumours of the brain are a rare occurrence accounting for approximately 2% of all neoplasms in adults. Few studies have been done in Nigeria on the profile of brain tumours. The aim of this study is to determine the profile of brain tumours in general and determine the change in Kanofsky Performance Score (KPS) after treatment. Methods : This is a prospective hospital-based study in Kaduna. All consecutive patients over 18 years of age with diagnosis of brain tumours from January 2016 to December 2019 were included in the study. Demographic and clinical data was collected using a proforma during the study. Patients who received treatment were followed up for 12 months. The primary outcome data was the difference in the quality of life as measured by KPS at the point of first contact and at 1-month after treatment and at 12-month follow up. Data obtained was analysed with SPSS version 25.0 for Windows. Descriptive statistics was done to determine the profile. Paired t-test at 95% confidence interval was done to check for significant correlation between the mean KPS. Results : A total of 39 consecutive patients were included in the study. There was a slight male preponderance with a M : F of 1.17 : 1. Meningioma and metastasis were more common in females while gliomas and pituitary tumours were more common in males. The mean age of patients was 49.8 years and standard deviation of 11.8 years. Pituitary tumours were the most common tumours. The most common location of the tumour was frontal lobe followed by the pituitary gland. The mean duration of symptoms before neurosurgical consultation was 38 weeks. The most common presenting symptoms of patient with brain tumour was headache. The quality of life improve compare to the baseline in 81% of patient at discharge and at 1 year follow up. The overall mortality rate was 25.6%. Conclusion : The most common brain tumour in our study is pituitary tumour. Most patients present late. The most common presenting symptoms is headache. There is significant improvement in the KPS of patients following treatment. The overall mortality rate at 1-year post treatment is 25.6%.

• 대한후두음성언어의학회지
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• 제15권1호
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• pp.16-20
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• 2004

Purpose : To assess perceptual, acoustic and aerodynamic measure of voice quality in patients with unilateral vocal cord paralysis before and after type I thyroplasty. Methods : The clinical records of patients operated type I thyroplasty in the Departement of otorhinoalryngolgy, Yongdong Severance hospital from November 2001 to November 2003 were reviewed. All patients uderwent a vocal function evaluation including perceptual, acoustic and aerodynamic measures of voice preoperative and on $60^{th}$ postoperative day. The perceptual and acoustic measures were obtained from recording of patients' reading a 'Sanchak' passage. The perceptual evaluation was performed by 2 speech pathologist using a 4-point rating scale. Acoustic parameters(voice range profile low(RAL), voice range profile high(RAH), average fundamental frequency(AFX), closed quotient, harmonic to noise ratio, jitter and shimmer) were investigated by Lx speech studio. Mean flow rate(MFR), subglottic pressure(Psub) and intensity were measured using the Phonatory function analyzer. The maximum phonation time was also measured. The data were statistically analyzed. A paired t-test (p<0.1) was used to compare preoperative and postoperative results. And multiple regression test was used to find which parameter was most correlated to improvement of postoperative voice quality. Results : Among aerodynamic parameters, Psub $(88.11mmH_2O{\rightarrow}58.7mmH_2O)$, MPT(7.87sec${\rightarrow}$12.53sec), MFR (359.8ml/sec${\rightarrow}$161.06ml/sec) were statistically improved. AFx(205.5Hz${\rightarrow}$163.27Hz), AQx(23.9%${\rightarrow}$48.3%), RAL, RAH. Jotter and shimmer were improved. In multiple regression test, AFx and AQx was noted as the two meost correlated parameters to improvement of postoperative breathiness. But general grade of voice quality was more correlated to Psub and shimmer. Conclusion : Vocal fold medialization procedures effectively reduce glottic gap. Increasing of contact area of both vocal folds induced improvement in aerodynamic parameters and leaded stabilizing of vocal fold vibration. That effect results in improvement in acoustic parameters (shimmer, jitter, signal-to-noise ratio, voice range profile) and voice quality.

• 한국환경보건학회지
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• 제46권1호
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• pp.103-109
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• 2020

Objectives: Using as a sleep evaluation tool the Pittsburgh Sleep Quality Index (PSQI), this paper studied the effects of earthing on the amount and quality of sleep by examining a patient population of people who used and did not use earthing mats and a group of general healthy people. Methods: From September to November 2019, 30 patients who voluntarily used an earthing mat, 40 patients who did not use an earthing mat, and 40 healthy people who did not use an earthing mat were selected. A questionnaire applying the PSQI (Pittsburgh Sleep Quality Index) after being translated into Korean was distributed starting November 29, 2019 to 110 subjects. Out of them, 101 subjects who completed the questionnaire were examined. All statistics used SPSS 25.0. Results: The first overall score showed that all three groups had problems sleeping, with five points or more, but the general population had better sleep quality than the patient group. It also showed that the using matgroup had better quality of sleep than the ones that did not use the earthing mat In addition, the analysis of the third group through the variance analysis showed significance at >0.05 for the general population and the patient group. Based on this, a multi-comparison analysis of the third group showed significantly less than 0.05 in patients who do not use an earthing mat compared to the public. First of all, there are no statistically significant differences between the three groups in subjective sleep quality, sleep latency, and sleep time, but an analysis of multiple comparison analysis with the general population group showed that the quality of sleep was worse compared to those that used the mat. In addition, sleep efficiency, sleep disorder, sleeping pills, and daytime dysfunction were found to be less than >0.05 in the three groups. Conclusions: These results suggest that if you ground your body to Earth during sleep, the secretion of cortisol will decrease night levels, sync more with the natural 24-hour circulation rhythm profile, and that when you sleep, sleep is better and pain and stress are associated with the study. While the preceding study cannot confirm that contact with the ground affects the quality of sleep, it suggests that it is relevant as shown in this paper.

• 대한치과기공학회지
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• 제22권1호
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• pp.89-112
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• 2000

Although dental laboratory technicians are prone to be exposed to various work-related health hazardous materials such as dusts, chemicals, etc., the prevalence and nature of work-related health problems of them have not been a matter of great concern in the field of occupational health service in Korea. The purpose of the present investigation was to describe a collected profile of subjective health symptoms and their attributable factors in Korean dental laboratory technicians. A questionnaire listing five groups of health symptoms and five health symptom-related factors was mailed to randomly selected 1,900 dental laboratory technicians. Among them, 1,344 dental laboratory technicians filled out the questionnaires and returnde them. Five groups of health symptoms included musculoskeletal symptom, dermal symptoms, respiratory symptoms, eys symptoms, and ear symptoms. Five health symptom-related factors were occupational environment-related health risk factors, work history, health related habits and status, use of personal protective equipment and general characteristics. Detailed parameters of health risk factors were work posture, vibration, and chemical or physical hazards such as dust, fume, vapor, solvent, light, and noise for occupational environment-related factors; work place, area, number of employees, work hours, career, work part, and work load for work history; Broca's index, hours of sleep, eating, smoking, alcohol, exercise, health examination, and self assessed health status for health habits and status; face masks, goggles, and so on for use of personal protective equipment, and; age, sex, marital status, and education for general characteristics. Before the start of main survey, a pilot survey was carried out for validity and reliability tests of the questionnaire. All the data obtained were coded and analyzed with PC/SAS 6.12 program. The prevalence of health symptoms was the highest in musculoskelton (87.3%), and followde by eyes (78.9%), respiratory organs (64.3%), ears (57.8%), and skin (52.2%) in descending order. Statistically significant risk factors by multiple logistic regression analyses were sex, health examination, self assessed health status, and hand/finger posture in musculoskeletal symptoms; sex, self assessed health status, career, acid gas, and hand contact with resin mixture in deraml symptoms; Broka's smoking, exercise, self assessed health status, and face mask in respiratory symptoms; sex, hours of sleep, self assessed health status, work hours, work load, plaster dust, inadequate lighting, and goggle in eys symptoms, and eating, smoking, self assessed health status, and work load in ear symptoms. With the above considerations in mind, prevalence of subjective symptoms among Korean dental laboratory technicians was relatively high, and they were attributable to most of the occupational environment-related factors, work history, use of personal protective equipment, health habits and status, and general characteristics. Particularly, it is suggested that health promotion programs for promoting self- assessed health status and smoking cessation, preventive measures for protection of the female technicians’health, and reducing work load be necessary, since those factors were associated with more than one subjective symptom.