• 보건교육건강증진학회지
• /
• 제28권5호
• /
• pp.97-104
• /
• 2011

Objectives: The purpose of this study was to examine the effect of smoking on aerobic physical fitness among physical education major male university students participating in regular exercise. Methods: A group of 42 healthy male students majoring physical education were divided into two groups: non-smokers (n=$26, 20.61{\pm}2.78 $yrs) and smokers (n=16, $21.25{\pm}2.29 $ yrs). Graded exercise testing for maximal oxygen consumption ($VO_2max$) was measured by Bruce protocol. Results: $VO_2max$ was not different between non-smokers and smokers, however, exercise duration time in non-smokers was more longer than smokers'. In non-smokers, ventilatory threshold (VT) time was delayed longer than smokers (p<0.01). %VT/VEmax was significantly different between non-smokers and smokers (p<0.01). Resting heart rate (p<0.01) and recovery heart rate at 80 seconds (p<0.01) in non-smokers were significantly lower than those of smokers. The decrease in heart rate recovery in non smokers was greater than in smokers at 40(p<0.05), 60(p<0.05) and 80(p<0.01) seconds. Conclusions: These results suggest that smoking has negative effects on aerobic fitness of male university students in physical education major.

• Journal of Preventive Medicine and Public Health
• /
• 제46권1호
• /
• pp.10-18
• /
• 2013

Objectives: We investigated the association between particulate matter less than $10{\mu}m$ in aerodynamic diameter ($PM_{10}$) exposure and non-accidental mortality in Asian populations by meta-analysis, using both time-series and case-crossover analysis. Methods: Among the 819 published studies searched from PubMed and EMBASE using key words related to $PM_{10}$ exposure and non-accidental mortality in Asian countries, 8 time-series and 4 case-crossover studies were selected for meta-analysis after exclusion by selection criteria. We obtained the relative risk (RR) and 95% confidence intervals (CI) of non-accidental mortality per $10{\mu}g/m^3$ increase of daily $PM_{10}$ from each study. We used Q statistics to test the heterogeneity of the results among the different studies and evaluated for publication bias using Begg funnel plot and Egger test. Results: Testing for heterogeneity showed significance (p<0.001); thus, we applied a random-effects model. RR (95% CI) per $10{\mu}g/m^3$ increase of daily $PM_{10}$ for both the time-series and case-crossover studies combined, time-series studies relative risk only, and case-crossover studies only, were 1.0047 (1.0033 to 1.0062), 1.0057 (1.0029 to 1.0086), and 1.0027 (1.0010 to 1.0043), respectively. The non-significant Egger test suggested that this analysis was not likely to have a publication bias. Conclusions: We found a significant positive association between $PM_{10}$ exposure and non-accidental mortality among Asian populations. Continued investigations are encouraged to contribute to the health impact assessment and public health management of air pollution in Asian countries.

• 한국구조물진단유지관리공학회 논문집
• /
• 제28권1호
• /
• pp.32-38
• /
• 2024

공동주택의 경우 사람의 실거주 및 코어시험 시 일어나는 분진 및 소음 등으로 인하여 비파괴검사를 진행하기 어려워 공용부 및 지하 주차장에서 매번 점검이 이루어지며, 저가 수주로 인한 콘크리트 면의 실험이 아닌 마감재 위에서 실험을 진행하여 부실점검이 발생할 수 밖에 없는 실정이다. 또한 강도 추정을 위한 제안식들은 시험조건과 환경의 차이에 따라 변동폭이 크고, 동일한 측정값을 나타내더라도 제안식 마다 그 편차가 커 정확한 강도 추정이 어려워 사용에 어려움을 겪고 있는 실정이다. 이에 공동주택에 주로 사용되는 마감재를 선정하여 마감재를 제거하지 않고 직접 마감재에 비파괴검사법을 활용하여 마감재 종류에 따른 콘크리트 압축강도 비교 평가를 하고자 한다. 마감재 종류에 따른 초음파속도법을 이용한 콘크리트 추정압축강도 신뢰도 평과 결과는 다음과 같다. 초음파속도법을 통해 도출된 추정압축강도와 압축강도의 오차율은 21.83% ~58.89%로 광범위한 변동폭을 보이며. 추정압축강도에 대한 마감재 유무의 영향은 미비한 것으로 나타났다. 이에 마감재 종류를 더 선정하여 마감재 유무에 따른 초음파속도법 연구가 필요하며 신뢰도를 높일 수 있는 추정기법 연구가 필요하다.

• Asian Pacific Journal of Cancer Prevention
• /
• 제17권10호
• /
• pp.4689-4692
• /
• 2016

Purpose: To study the clinical application value of ultrasound guided thyroid fine needle aspiration biopsy and thinprep cytology testing in diagnosis of thyroid disease. Methods: A total of 78 patients with thyroid nodules were enrolled, 34 males and 44 females, aged 33-64 years old with mean age of 47.6 years. All underwent thyroid module fine needle puncture after surgery to assess cell pathology and histopathological features. Results: Sufficient specimens were obtained from all of 78 patients, the cytological results of 73 cases (93.6 %) being consistent with pathological results. While 20 cases (25.6 %) were malignant tumors, 44 (56.4 %) were benign and 9 (11.5 %) were non-tumor lesions. The sensitivity of benign and malignant thyroid nodule by thyroid fine needle puncture was 90.9 %, specificity was 98.1 % and the positive predictive value was 96.3 %. Conclusions: It is demonstrated that ultrasound-guided thyroid fine needle aspiration biopsy and thinprep cytology testing have diagnostic value in clinical application for thyroid disease,showing good diagnostic coincidence rates with histopathological examination. They can thus be regarded as safe and effective for preoperative diagnosis and providing an appropriate basis for selection of surgery.

• Journal of Welding and Joining
• /
• 제18권1호
• /
• pp.46-51
• /
• 2000

Ultrasonic nondestructive evaluation (UNDE) technique is commonly used for detecting inner defects in the materials. Recently, new methods are trying to apply for detecting surface and subsurface flaws using Rayleigh wave or creeping wave. These techniques, however, have following problems. Echo amplitude is remarkably affected by the surface conditions and discrimination of echo pattern is usually difficult because shear wave propagate in the material at the same time. We can apply surface SH-wave(which is horizontally polarized shear wave traveling along near surface layer) technique to detect surface flaws. In this paper, directivity, distance amplitude characteristics and detectability of surface flaws at fillet weld hills of the 5 MHz and 2 MHz surface flaws at fillet weld hills of the 5 MHz and 2 MHz surface Sh-wave are experimentally investigated. As a result of the study, it was found out that these techniques are valuable for the detection of fatigue cracks at fillet weld heels which can not be detected by other ultrasonic techniques such as angle beam technique and which are inaccessible for non-destructive testings e.g. MT(magnetic particle testing) or PT(liquid penetrant testing).

• Composites Research
• /
• 제27권4호
• /
• pp.152-157
• /
• 2014

Non-destructive testing methods of composite materials are very important for improving material reliability and safety. AE measurement is based on the detection of microscopic surface movements from stress waves in a material during the fracture process. The examination of AE is a useful tool for the sensitive detection and location of active damage in polymer and composite materials. FBG (Fiber Bragg Grating) sensors have attracted much interest owing to the important advantages of optical fiber sensing. Compared to conventional electronic sensors, fiber-optical sensors are known for their high resolution and high accuracy. Furthermore, they offer important advantages such as immunity to electromagnetic interference, and electrically passive operation. In this paper, the crack detection capability of AE (Acoustic Emission) measurement was compared with that of an FBG sensor under tensile testing and buckling test of composite materials. The AE signals of the PVDF sensor were measured and an AE signal analyzer, which had a low pass filter and a resonance filter, was designed and fabricated. Also, the wavelength variation of the FBG sensor was measured and its strain was calculated. Calculated strains were compared with those determined by finite element analysis.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제18권1호
• /
• pp.33-39
• /
• 2018

Purpose: Accelerated degradation tests can be effective in assessing product reliability when degradation leading to failure can be observed. This article proposes an accelerated degradation test model for highly reliable solid state drives (SSDs). Methods: We suggest a nonlinear mixed-effects (NLME) model to degradation data for SSDs. A Monte Carlo simulation is used to estimate lifetime distribution in accelerated degradation testing data. This simulation is performed by generating random samples from the assumed NLME model. Conclusion: We apply the proposed method to degradation data collected from SSDs. The derived power model is shown to be much better at fitting the degradation data than other existing models. Finally, the Monte Carlo simulation based on the NLME model provides reasonable results in lifetime estimation.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제16권3호
• /
• pp.224-230
• /
• 2016

Purpose: Military maintenance involves corrective and preventive actions carried out to keep a system in or restore it to a predetermined condition. This research develops an optimal maintenance cycle for aviation oil testing equipment with acceptable reliability level and minimum maintenance cost. Methods: The optimal maintenance policy in this research aims to satisfy the desired reliability level at the lowest cost. We assume that the failure process of equipment follows the power law non-homogeneous Poisson process model and the maintenance system is a minimal repair policy. Estimation and other statistical procedures (trend test and goodness of fit test) are given for this model. Results: With time varying failure rate, we developed reliability-based maintenance cost optimization model. This model will reduce the ownership cost through adopting a proactive reliability focused maintenance system. Conclusion: Based on the analysis, it is recommended to increase the current maintenance cycle by three times which is 0.5 year to 1.5 years. Because of the system's built-in self-checking features, it is not expected to have any problems of preventative maintenance cycle.

• 한국간호교육학회지
• /
• 제21권4호
• /
• pp.477-489
• /
• 2015

Purpose: The purpose of this study was to develop an instrument to assess emergency room nurses' knowledge and performance of triage nursing. Methods: The instrument was developed through the stages of conceptual construction, item development, and validity and reliability testing. For the validity and reliability testing, data collected from 48 emergency room nurses using questionnaires was analyzed through descriptive statistics, factor analysis, and reliability coefficients. Results: The knowledge part consisted of 30 items in nine areas, and its reliability was low (KR-20 =0.50). The correct-answer rate was 71.8%. The performance section derived from the factor analysis was composed of two factors with nine items in the triage domain and three factors with 12 items in the non triage domain. The explanatory powers of these factors for the domains were 66.1% and 70.4%, respectively. The overall reliability (Cronbach's ${\alpha}$) was .95, and the reliabilities for the two domains were .88 and .91, respectively. The nurses' mean performance level was 3.2(${\pm}0.45$). Conclusion: The specific contents of the triage nursing work were identified from the developed scale; further research is necessary to in order to develop a scale capable of higher reliability and validity.

• The Journal of Korean Physical Therapy
• /
• 제29권3호
• /
• pp.142-144
• /
• 2017

Purpose: Few studies have addressed the effect of diurnal circadian rhythms on postural stability, and thus the aim of the present study was to examine circadian effects on static and dynamic postural stability in young adults. Methods: Twenty-four subjects (9 men, 11 women: age=$22.20{\pm}1.77$, height=$167.20{\pm}10.47$, weight=$59.85{\pm}10.66$) from a university community volunteered for this study. Static and dynamic balance testing, which recorded using a Good Balance system (Good Balance, Metitur Ltd, Finland) was conducted at 9:00, 13:00, and 17:00 hours on two consecutive days, and the sequencing of static and dynamic balance tests were randomized. Results were analyzed using the non-parametric one-way repeated Friedman test in SPSS version 18.0 (SPSS Inc., Chicago, IL, USA), and variable found to be significant were subjected to Wilcoxon post hoc testing. Results: Static and dynamic balance showed significant difference at the three times assessments (test at 9:00, 13:00, and 17:00) during circadian. In the post hoc test of static (anteroposterior distance, mediolateral distance and COP (center of pressure) velocity) and dynamic balance (performance time), 13:00 was the longer and faster than 9:00. Conclusion: These results indicated that control of postural balance is influenced by diurnal circadian rhythms, and confirm that control of postural balance is more effective and better performance in the 09:00 hours than 13:00 hours or 17:00 hours.