• 대한인간공학회지
• /
• 제15권2호
• /
• pp.37-49
• /
• 1996

Morningness-Eveningness Questionnaire (MEQ) of Horne & Ostberg(1976) was translated into a Korean version, and MEQ and life habit inventory was administrated with approximately 900 university students. The distribution of MEQ score was normal. Arising time and bedtine for weekdays and holidays came in the order of morning type, intermediate and evening-type. And the deviation for the evening-type was greatest. Also, the deviation of sleep length for the evening-type was greater than the morning- type. There were tendencies that the bed time and arising time of the male were slightly later than those of the female, and the sleep length of the male was a little longer than that of the female. It also appeared that the arising time was later in the male who completed the military services than those who did not in the chronotype. And the sleep length of the non-served male was longer than that of the served one. Such tendencies noticeably appeared especially the evening-type. The evening-type was subject to heavy variability in bedtime. arising time, and sleep length. The sleep latency of the evening- type was longer and mood on arising was worse. And the ratio of nap or light sleep was higher in these subjects than in others. These results suggested that evening-type students had more irregular and/or flexible sleep-wake habits than the morning-type.

• Computers and Concrete
• /
• 제2권2호
• /
• pp.125-146
• /
• 2005

The objective of this paper is setting out, for a cable-stayed bridge with a curtain suspension, a method to determine the modes of vibration of the structure. The system of differential equations governing the vibrations of the bridge, derived by means of a variational formulation in a nonlinear field, is reported in Appendix C. The whole analysis results from the application of Hamilton's principle, using the expressions of potential and kinetic energies and of the virtual work made by viscous damping forces of the various parts of the bridge (Monaco and Fiore 2003). This paper focuses on the equation concerning the transversal motion of the girder of the cable-stayed bridge and in particular on its final form obtained, restrictedly to the linear case, neglecting some quantities affecting the solution in a non-remarkable way. In the hypotheses of normal mode of vibration and of steady-state, we propose the resolution of this equation by a particular method based on a numerical approach. Respecting the boundary conditions, we derive, for each mode of vibration, the corresponding frequency, both natural and damped, the shape-function of the girder axis and the exponential function governing the variability of motion amplitude in time. Finally the results so obtained are compared with those deriving from the dynamic analysis performed by a finite elements calculation program.

• 대한토목학회논문집
• /
• 제8권3호
• /
• pp.85-90
• /
• 1988

균질토 사면에서 파괴에 대한 확률론적모델이 제시되었다. 사면의 안전은 관례적인 안전을 보다는 파괴확률로써 측정된다. 사면파괴의 Safety Margin은 정규분포라 가정하였다. 어떤 균질한 흙층에 있어서 흙의 특성에 영향을 주는 불확실성의 원인은 본래의 공간적인 가변성, 불충분한 시료에서 오는 판단오차 그리고 실험오차등이 었다. 파괴면을 따라 존재하는 전단강도의 불확실성은 1차원 Random Field Madels로 표현되었다. 파괴aus의 양상은 대수나선 곡선을 따른다고 가정하였다. 파괴면과 그것을 따라 작용하는 힘의 통계적 특성을 유도하여 사면의 파괴확률을 계산하였다. 마지막으로 개발된 절차가 사면의 신뢰성 해석에 대한 하나의 예제 연구에 적용되었다.

• 대한통합의학회지
• /
• 제4권4호
• /
• pp.77-82
• /
• 2016

Purpose: The purpose of this study was to investigate the therapeutic effect of non-invasive vagus nerve stimulation by transcutaneous electrical nerve stimulation application on the autonomic nervous system of human body. Methods: Participants were seventeen healthy adults. Standard deviation of all normal N-N intervals(SDNN), root mean square of successive differences(RMSSD), low frequency(LF), high frequency(HF) were compared in pre and post Mean values after intervention. Data were analyzed in Wilcoxon's signed-ranks test. Results: The results of this study is that sistolic blood pressure and pulse rate decreased mean value after non-invasive vagus nerve stimulation by transcutaneous electrical nerve stimulation. High frequency, low frequency, SDNN, RMSSD increased mean value in heart rate variability after intervention. But that is not significant except for SDNN. Conclusion: Non-invasive vagus stimulation by transcutaneous electrical nerve stimulation effect on parasympathetic nerve stimulation, and then it might be effective method for autonomic nerve balance control.

• 한국정밀공학회지
• /
• 제31권5호
• /
• pp.459-466
• /
• 2014

An index was developed that estimates cardiovascular health degree with easily available physiological information such as survey and noninvasive measurement. The survey score was calculated by utilizing questions related to personal disease history, self-feeling, and management state. The measurement score was calculated using physiological parameters such as blood pressure, accelerated plethysmograph(APG), and heart rate variability(HRV), and augmentation index(AI). In order to evaluate effectiveness of the cardiovascular index and modify weighting factors used in each item, a clinical trial was done in a general hospital. The cardiovascular index showed a clear correlation of 0.685 with the doctor's score on the cardiovascular health degree. The correlation between the self-estimated score and doctor's score was as low as 0.217. The large gap between these two scores demonstrated necessity of more objective tools like the cardiovascular index. The cardiovascular score showed a significant difference between normal persons and patients suffering hypertension or diabetes. (p=0.000).

• 대한한방부인과학회지
• /
• 제31권2호
• /
• pp.80-94
• /
• 2018

Objectives: The purpose of this study was to investigate the effect of the massage program stimulating the acupuncture points and meridians on the improvement of sleep quality. Methods: 16 subjects suffering from sleep disorders were recruited and the massage program was conducted 3 times a week for a month. VAS (Visual Analog Scale) and KPSQI (Korean Pittsburgh Sleep Quality Index) were collected through questionnaires, and salivary cortisol concentration test and HRV (Heart Rate Variability) were also used to evaluate the effect. The collected data were analyzed by independent statisticians. Results: VAS and KPSQI values decreased significantly after 4 weeks of massage chair application. There was no significant difference in salivary cortisol concentration and HRV test results. In the group with normal HRV test results and salivary cortisol concentration, the change of VAS and KPSQI values was not significant, while the group with abnormal range showed a statistically significant decrease. Conclusions: The massage chair program stimulating meridians according to Korean medicine theory was effective in improving sleep quality. Massage of acupoints and meridians through a massage chair is expected to be useful as an adjunctive therapy in addition to standard Korean medicine therapy.

• 한국지역사회생활과학회지
• /
• 제22권4호
• /
• pp.623-635
• /
• 2011

Over the past few decades, the proportion of elderly people with depression in Korea has been rapidly increasing. The purpose of this study is to explore relative effects of health and family factors on geriatric depression. The data sources are from Korean Longitudinal Study of Aging(2008). The Analysis sample consists of 4,040 cases. Analysis results show that there is a significant variability in geriatric depression according to sociodemographic characteristics, health characteristics, and family characteristics. Hierarchical logistic regression analyses are employed to assess the causal relationship between health characteristics and geriatric depression. Model II showed that ADL(exp(B)=1.732), having difficulties due to sight deterioration(exp(B)=1.398), having difficulties due to masticatory force deterioration(exp(B)=1.414), having difficulties due to pain(exp(B)=2.435), and subjective health status(exp(B)=2.010) are reported as predictors of geriatric depression. Namely, the probability of having geriatric depression of the above predictors has been 1.7 times, 1.4 times, 1.4 times, 2.4 times. 2.0 times higher than normal figures. Among health characteristics, pain is the most prevalent factor. Model III showed that as for family characteristics, coresiding with children(exp(B)=1.312) and frequency of contacting with children by phones, letters, or emails(exp(B)=1.477) are reported as predictors of geriatric depression. Key findings are that health factors have larger effects than family factors on geriatric depression.

• International Journal of Reliability and Applications
• /
• 제8권2호
• /
• pp.153-173
• /
• 2007

Wood-plastic composites (WPC) are gaining market share in the building industry because of durability/maintenance advantages of WPC over traditional wood products and because of the removal of chromated copper arsenate (CCA) pressure-treated wood from the market. In order to ensure continued market share growth, WPC manufacturers need greater focus on reliability, quality, and cost. The reliability methods outlined in this paper can be used to improve the quality of WPC and lower manufacturing costs by reducing raw material inputs and minimizing WPC waste. Statistical methods are described for analyzing stiffness (tangent modulus of elasticity: MOE) and flexural strength (modulus of rupture: MOR) test results on sampled WPC panels. Descriptive statistics, graphs, and reliability plots from these test data are presented and interpreted. Sources of variability in the MOE and MOR of WPC are suggested. The methods outlined may directly benefit WPC manufacturers through a better understanding of strength and stiffness measures, which can lead to process improvements and, ultimately, a superior WPC product with improved reliability, thereby creating greater customer satisfaction.

• Water Engineering Research
• /
• 제2권1호
• /
• pp.63-72
• /
• 2001

The variation of sampling errors was characterized using the Waymire-Gupta-Rodriguez-Iturbe multi-dimensional rainfall model(WGR model). The parameters used for this study are those derived by Jung et al. (2000) for the Han River Basin using a genetic algorithm technique. The sampling error problems considered are those for using raingauge network, satellite observation and also for both combined. The characterization of sampling errors was done for each month and also for the downstream plain area and the upstream mountain area, separately. As results of the study we conclude: (1) The pattern of sampling errors estimated are obviously different from the seasonal pattern of monthly rainfall amounts. This result may be understood from the fact that the sampling error is estimated not simply by considering the rainfall amounts, but by considering all the mechanisms controlling the rainfall propagation along with its generation and decay. As the major mechanism of moisture source to the Korean Peninsula is obviously different each month, it seems rather normal to provide different pattern of sampling errors from that of monthly rainfall amounts. (2) The sampling errors estimated for the upstream mountain area is about twice higher than those for the down stream plain area. It is believed to be because of the higher variability of rainfall in the upstream mountain arean than in the down stream plain area.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1996년도 춘계학술대회
• /
• pp.320-324
• /
• 1996

Digital fetal monitoring system based on the personal computer combined with the digital signal processing board was implemented. The DSP board acquires and digitally processes ultrasound fetal Doppler signal for digital rectification, FIR filtering, autocorrelation function calculation, its peak detection and MEDIAN filtering. The personal computer interfaced with the DSP board is in charge of graphic display, hardcopy, data transmission and on-line analysis of fetal heart rate change including and variability. I used a recursive technique for autocorrelation function computation method and MEDIAN filter which can greatly reduce the amount of calculation and accuracy. I also implemented analysis algorithm of fetal heart rate change based on normal fetal sample data in order to exact diagnosis.