• 대한의용생체공학회:의공학회지
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• 제22권2호
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• pp.197-204
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• 2001

• 정보처리학회논문지C
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• 제17C권3호
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• pp.299-306
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• 2010

IPTV 및 VoIP 서비스는 높은 이동성과 전송 속도를 보장하는 Mobile WiMAX 네트워크 상에서 제공할 수 있는 유용한 응용 서비스들이다. IPTV의 오디오 전송이나 VoIP의 통화 품질에 영향을 미치는 요소 중 전송 경로의 잦은 변경이나 경로간 전송 시간의 차이에 따라 발생하는 지터에 의한 패킷 손실은 지터 버퍼를 이용하여 완화할 수 있다. 본 논문에서는 Mobile WiMAX 네트워크 상에서 이동 단말의 전력 소모 절감을 위해 사용되는 PSC-II 모드를 사용할 때의 오디오 및 음성 서비스의 품질(Quality of Service)과 지터 버퍼 크기의 상관관계에 대해 연구, 분석한다. 이를 위해 절전 모드 사용으로 인해 추가로 발생하는 지연 시간을 포함한 서비스의 종단간 지연시간 모델과 종단간 지연시간을 기준으로 한 서비스 품질 기준을 제시하였다. 또한, 제시한 모델의 다양한 파라미터에 따른 시뮬레이션 분석 결과를 통해 절전 모드를 사용할 경우에는 지터 버퍼의 크기 증가에 따른 지연으로 인한 패킷 손실이 오히려 오디오 및 VoIP 서비스 품질 측면에서 좋지 않은 영향을 미칠 수 있음을 보였다.

• 한국인터넷방송통신학회논문지
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• 제19권3호
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• pp.91-96
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• 2019

센서네트워크를 위한 여러 가지 저전력 MAC들이 제안되어 있다. 그 중 IEEE802.15.4은 동기화로 인한 전력소모가 많은 단점을 가지며 전력소모를 줄이기 위한 수면(sleep)과 각성(awake)을 반복하는 슈퍼프레임(superframe) 동작으로 지연시간이 길어지는 단점이 있다. 대표적 비동기 B-MAC은 체크인터벌에 따라 지연시간을 짧게 할 수는 있지만 송신단에서는 과도한 프리엠블로 전력소모가 발생하며 수신단에서는 오버히어링으로 전력 손실이 발생하는 단점을 가진다. 기존 MAC들의 지연시간과 전력소모 불균형으로 인한 단점을 보완하기 위해 비동기식 B-MAC 기법에 체크인터벌을 적응형으로 운용하는 방법을 제안하고 전력소모 성능을 분석한다.

• 한국전자통신학회논문지
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• 제8권6호
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• pp.823-829
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• 2013

IEEE 802.16 표준 규격[1]은 광대역무선접속시스템을 구현하기 위한 기술을 명시하고 있고 특히 이동 단말의 전력 소모를 최소화하기 위한 슬립모드(sleep mode)에 대한 내용도 포함되어 있다. 본 논문에서는 IEEE 802.16 표준 규격에 기술되어 있는 슬립모드의 기본 동작에 대해서 설명하고 이동 단말의 전력절감효율을 높일 수 있는 개선 방안을 제안한다. 제안하는 방안은 기존의 트래픽 인디케이션 메시지의 형식을 다소 수정함으로써 슬립모드에 있는 이동단말이 주기적으로 수신해야 하는 데이터 량을 줄이는 동시에 주기적 레인징과 같은 동작을 지시할 수 있다는 장점이 있다.

• 대한간호학회지
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• 제36권5호
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• pp.829-836
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• 2006

Purpose: The purpose of the present study was to identify prevalence of excessive daytime sleepiness(EDS) and its associations with sleep habits, sleep problems, depression, subjective health status and obesity in community dwelling adults. Method: Data was collected from adults aged 20-59 years by random sampling. Subjects completed a questionnaire which was composed of the Epworth Sleepiness Scale, Center for Epidemiologic Studies Depression Scale, and questions that included items about sleep habits, sleep problems, subjective health status and sociodemographic characteristics. Height and weight were measured for calculation of body mass index. The statistical analyses was based on 3,302 adults (51.5% males and 48.5% females). Descriptive statistics, univariate logistic regression and multiple logistic regression were used. Result: The prevalence of EDS was 17.1% Multiple logistic regression showed that the associated factors of EDS were depression, obesity, dissatisfaction with sleep time, irregular sleep, and habitual snoring. Depression was the most significant associated factor(adjusted odds ratio for severe depression=2.27, 95% Confidence Interval=1.73-2.96). Conclusion: EDS is a common symptom in adults. Our finding suggested that persons with a complaint of EDS should be completely assessed for depression and obesity as well as sleep problems.

• 한국컴퓨터정보학회논문지
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• 제22권11호
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• pp.17-23
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• 2017

In this paper, we implemented a respiration measurement system consisting of piezoelectric sensor, respiration signal processing device, and a viewer on a notebook. We tried an experiment for measuring respiration and detecting sleep apnea syndrome when a subject lay on a bed. We applied the respiration measurement algorithm to sensor data obtained from four subjects. In order to get a good graph shape, data manipulation methods such as moving averages and maximum values were applied. The window size for moving average was chosen as N=70, and the threshold value for each subject was customized. In this case, the proposed system showed 96.0% accuracy. When the maximum value among 90 data was applied instead of moving average, our system achieved 95.1% accuracy. In an experiment for detecting sleep apnea syndrome, the system showed that sleep apnea occurred correctly and calculated the average interval of sleep apnea. While infants or the elderly as well as patients with sleep apnea syndrome are lying down on a bed, our results are also expected to be able to cope with some accidental emergency situation by observing their respiration and detecting sleep apnea.

• Child Health Nursing Research
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• 제30권2호
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• pp.77-86
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• 2024

Purpose: This study examined the combined effects of sugar-sweetened beverage (SSB) consumption, screen-based sedentary behaviors, and sleep duration on adolescent obesity. Methods: It followed a cross-sectional study design and conducted secondary analysis on data from 20,497 high school students who participated in the 17th (2021) Korea Youth Risk Behavior Web-based Survey. This study underwent logistic regression analysis in complex sampling analysis. Results: The combinations of low and medium consumption of SSBs, excessive screen-based sedentary behaviors, and short sleep durations were associated with a 1.18 and 1.12 fold increased likelihood of obesity (95% confidence interval [CI]=1.03-1.35) and (95% CI=1.02-1.22), respectively. The combination of high SSB consumption, appropriate screen-based sedentary behaviors, and short sleep duration (adjusted odds ratio [aOR]=1.15, 95% CI=1.01-1.31) and high SSB consumption, excessive screen-based sedentary behaviors, and short sleep duration (aOR=1.40, 95% CI=1.16-1.69) were associated with obesity. Conclusion: Integrated and tailored programs considering combination patterns of SSB consumption, screen-based sedentary behaviors, and short sleep duration need to be developed for preventing adolescent obesity.

• Annals of Occupational and Environmental Medicine
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• 제34권
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• pp.27.1-27.12
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• 2022

Background: Shift work that interferes with normal sleep patterns, is known to be a cause of sleep disturbance and has been studied through various occupational groups. However, it is not known which shift type is better for sleep health. Methods: This study included 568 firefighters. Sleep quality was evaluated using Pittsburgh Sleep Quality Index. Sleep quality was categorized into 2 groups; good quality (≤ 5 points) and poor quality (≥ 6 points). Demographic variables, depression, anxiety, type of shift, and job were collected by self-reported questionnaires. The χ² test, t-test, and multiple logistic regression analysis were used to evaluate the effect of shift type on the sleep quality of firefighters. Results: Three hundred thirty-seven firefighters (59.3%) have poor sleep quality. Compared to day workers, the odds ratios (ORs) of poor sleep quality were 2.169 (95% confidence interval: 1.137-4.134) in 6-day cycle, 2.161 (1.150-4.062) in 9-day cycle, 1.805 (1.087-2.997) in 21-day cycle, and 1.485 (0.718-3.069) in 3-day cycle. The ORs of poor sleep quality were 1.697(1.021-2.823) in fire suppression and 2.325 (1.213-4.455) in emergency medical service compared to administration. Conclusions: All shift work type except for the 3-day cycle was associated with poor sleep quality compared to day work.

• Safety and Health at Work
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• 제6권3호
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• pp.240-248
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• 2015

Background: Recovery from fatigue is important in maintaining night workers' health. This study compared the course of self-reported recovery after 2-week 12-hour schedules consisting of either night shifts or swing shifts (i.e., 7 night shifts followed by 7 day shifts) to such schedules consisting of only day work. Methods: Sixty-one male offshore employees-20 night workers, 16 swing shift workers, and 25 day workers-rated six questions on fatigue (sleep quality, feeling rested, physical and mental fatigue, and energy levels; scale 1-11) for 14 days after an offshore tour. After the two night-work schedules, differences on the $1^{st}$ day (main effects) and differences during the follow-up (interaction effects) were compared to day work with generalized estimating equations analysis. Results: After adjustment for confounders, significant main effects were found for sleep quality for night workers (1.41, 95% confidence interval 1.05-1.89) and swing shift workers (1.42, 95% confidence interval 1.03-1.94) when compared to day workers; their interaction terms were not statistically significant. For the remaining fatigue outcomes, no statistically significant main or interaction effects were found. Conclusion: After 2-week 12-hour night and swing shifts, only the course for sleep quality differed from that of day work. Sleep quality was poorer for night and swing shift workers on the $1^{st}$ day off and remained poorer for the 14-day follow-up. This showed that while working at night had no effect on feeling rested, tiredness, and energy levels, it had a relatively long-lasting effect on sleep quality.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.136-142
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• 2014

Distinct features in heart rate signals during the driver's wake and sleep states could provide an initiative for the development of a safe driving systems such as drowsiness detecting sensor in a smart wheel. We measured ECG from health subjects ($23.5{\pm}2.5$ in age) during the wake and drowsiness states. The proposed method is able to detect R waves and R-R interval calculation in the ECG even when the signal includes in abnormal signals. Heart rate variability(HRV) was investigated for the time domain and frequency domains. The STD HR(0.029), NN50(0.044) and VLF power(0.0018) of the RR interval series of the subjects were significantly different from those of the control group (p < 0.05). In conclusion, there are changes in heart rate from wake to drowsiness that are potentially to be detected. The results in our study could be useful for the development of drowsiness detection sensors for effective real-time monitoring.