• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.559-561
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• 2004

최근 무선 통신 기술과 초소형화 기술의 진보로 지능형 센서(Smart Sensor)를 이용한 무선 센서 네트워크 구축이 가능해졌고, 이러한 센서 네트워크는 유비쿼터스 컴퓨팅와 Ad-Hoc 네트워크에서 많이 연구되고 있는 새로운 분야이다. 각 센서 노드는 건전지를 통해 전원을 공급받기 때문에. 제한된 에너지를 어떻게 효율적으로 사용하느냐가 센서 네트워크에서의 중요한 이슈이다. 일반적으로 센서네트워크에서 데이터 송수신에 참여하지 않는 노드는 일정 시간 Sleep함으로써 에너지를 절약한다. sleep 기술과 관계된 기존의 논문(S-MAC [1])에서는 동기화 및 NAV 설정을 위해 컨트롤 패킷(SYNC, RTS, CTS)을 사용하고, 컨트롤 패킷 전송 시간만큼은 최소한 모든 노드들이 깨어서 컨트롤 패킷의 송수신을 확인해야 한다. 본 논문에서는 컨트롤 패킷 전송 시간 동안 불필요하게 모든 노드들이 깨어있는 문제를 해결하기 위해, 새로운 센서 MAC 프로토콜(ESMAC: Efficient Sensor MAC)을 제시한다. ESMAC에서는 컨트롤 패킷 전송 시간동안 꼭 필요한 노드들만 컨트롤 패킷을 송수신하고, 나머지 노드들은 Sleep 함으로써, 모든 노드가 깨어있는 시간을 효율적으로 줄였다. 위와 같은 방법을 사용하여 ESMAC에서는 기존의 MAC(SMAC, TIPS [2]) 프로토콜들보다 컨트롤 패킷 전송 시간을 최대 62.8% 절약시켰다.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.20 no.3
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• pp.146-151
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• 2009

Objectives : We conducted this study to investigate the relationship between sleep duration and body mass index (BMI), in Korean children. Methods : We performed a cross-sectional analysis of data collected on 3,639 boys and girls (aged 7-12) in Daegu, Korea. The data included each child's age, sex, weight, height, extracurricular activities, bedtime, wake-up time, sleep latency, total sleep duration, parents' occupations, and parents' educational levels. The relationship between sleep duration and each variable was examined via analysis of variance (ANOVA). Results : The analysis showed an association between short sleep duration and high BMI. Boys showed a graded inverse relationship between sleep duration and BMI. However, there was no significant corresponding result for girls. In the total sample, hours of computer use, time when the computer was turned off, time when the television was turned off, mother's bedtime, and hours of extracurricular activity were associated with longer sleep duration. No association was found between sleep duration and hours of watching television, child's wake-up time, or educational level of the parents. Conclusion : The results of this study show an inverse relationship between a child's sleep duration and BMI；thus, children with shorter sleep duration tend to have higher BMIs.

• Korean Journal of Occupational Health Nursing
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• v.29 no.1
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• pp.69-77
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• 2020

Purpose: The prevalence of metabolic syndrome (MetS), a cluster of metabolic abnormalities has rapidly increased in Korea. Sleep may play a role in determining its prevalence. However, the relationships between MetS and the duration and quality of sleep are not yet clear. This study aimed to examine the associations between the duration and quality of sleep and the prevalence of MetS. Methods: Study participants included 348 Korean blue-collar workers employed by six small-sized companies in Korea. The data were collected using an interviewer-administered questionnaire, and logistic regression analysis was conducted to estimate the effects of the factors related to MetS. Results: The multiple logistic regression analysis revealed that the independent factors that contributed to the prevalence of MetS were being male (adjusted odds ratio [aOR]=4.87, 95% confidence interval [CI]=1.58~15.0) and lower sleep quality (aOR=5.12, 95% CI=1.90~14.30). Sleep duration was related to the prevalence of some MetS components, but it was not associated with MetS prevalence. Conclusion: Sleep quality was negatively associated with MetS prevalence when covariates, such as sleep duration, were controlled. When developing a MetS risk-reduction program, focus should be given to sleep quality as well as sleep duration in an intervention for Korean blue-collar workers.

• Sleep Medicine and Psychophysiology
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• v.20 no.2
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• pp.69-74
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• 2013

Introduction: Although it is well known that medical students are not getting an adequate amount of sleep, there have been only a few studies on the sleep patterns of medical students and the related factors. Therefore, the present study aimed to investigate the medical students' sleep patterns and the related factors. Methods: A questionnaire package was administered to the $1^{st}$ to $4^{th}$ year medical students at one medical school. It consisted of questions asking about their lifestyles as well as Pittsburgh sleep quality index (PSQI), Epworth sleepiness scale (ESS), global assessment of recent stress scale (GASS), the center for epidemiologic studies-depression scale (CES-D), and Moudsley obsessive-compulsive inventory (MOCI). A total of 352 students (206 males and 146 females) responded to the survey and the result was analyzed using the independent t-test, the chi-square test, the paired t-test, Pearson's correlation and ANOVA. p-values of less than 0.05 were considered statistically significant in analyses. Results: The weekend bedtime was significantly delayed (0 : 49 on weekday ; 1 : 34 on weekend ; t=-5.23, p<0.001), the weekend rise time was delayed (6 : 58 on weekday ; 9 : 30 on weekend ; t=-24.48, p<0.001) and the total sleep time was increased on weekends (5 : 36 on weekday ; 7 : 39 on weekend ; t=15.94, p<0.001). The PSQI score of all subjects was 6.43{\pm}2.64. PSQI was positively correlated with ESS (r=0.383, p<0.001), GASS (r=0.326, p<0.001), CES-D (r=0.393, p< 0.001), and MOCI (r=0.247, p<0.001), but not with GPA (r=0.072, p=0.228. The more senior students had lower PSQI, GASS, CES-D, and MOCI score (p<0.05). Conclusion: Medical students were experiencing a lack of sleep during weekdays as they have a later bedtime and earlier rise time, and consequently had more hours of sleep on weekends. Overall, the medical students were experiencing poor sleep quality and sleep deprivation. Poor sleep quality is associated with psychological problems (daytime sleepiness, stress, depression, and obsessive tendency).

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.7
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• pp.175-182
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• 2018

The purpose of this study is to analyze the effect of sleep environment on individual sleep and to calculate optimal sleep environment. The input and output data sets are selected and the optimized sleep environment information is calculated using the neuro-fuzzy technique. Provides optimal sleep environment considering sleep duration. The arousal ratio calculated by the proposed method is 12%, which is at least 5% lower than the previous studies.

• Sleep Medicine and Psychophysiology
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• v.15 no.2
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• pp.82-86
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• 2008

Objectives: Obstructive sleep apnea syndrome (OSAS) not only causes respiratory disturbances during sleep but also decreases the quality of nocturnal sleep through sleep fragmentation and sleep structure change. We aimed at comparing the changes in sleep fragmentation and structure between baseline (diagnostic) nocturnal polysomnography (NPSG) and nCPAP (nasal continuous positive airway pressure) titration trial. Methods: One hundred and three patients with a baseline night of respiratory disturbance index (RDI) of 5 or greater and reduced RDI score during nCPAP titration night were retrospectively selected for the study. Sleep fragementation and sleep structure between baseline NPSG and the NPSG during nCPAP titration were compared. Sleep fragmentation index (SFI) was defined as the total number of awakenings and shifts to stage 1 sleep divided by the total sleep time in hour. SFI and other polysomnographic parameters were statistically compared between the two nights. Results: SFI during baseline NPSG and nCPAP titration nights were $29.0{\pm}13.8$ and $15.2{\pm}8.8$, respectively, indicating a significant SFI decrease during nCPAP titration (t=9.7, p<0.01). SFI showed significant negative correlations with sleep efficiency (r=-0.60, p<0.01) and total sleep time (r=-0.45, p<0.01) and a positive correlation with RDI (r=0.28, p<0.01). Conclusion: Use of nCPAP, even during the titration, significantly decreases sleep fragmentation and improves sleep structure in OSAS patients. We suggest that SFI may be utilized as a measure of assessing OSAS severity and nCPAP efficacy.

• Journal of Naturopathy
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• v.11 no.1
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• pp.9-17
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• 2022

Background: No studies have reported on the effects of loess beddings on insomnia patients. Purpose: It studied the change in quality of life and quality of sleep after having 15 insomnia subjects use the bedding that emits far-infrared rays. Methods: After using loess bedding for the test group and general yellow bedding for the control group, the study was conducted in the form of a questionnaire on the WHO quality of life of the subjects. Results: In the overall quality of life evaluation, the pre-and post-changes significantly improved in the test group. Using loess bedding was greatly enhanced the physical change, the actual sleep time, and the quality of sleep of the test group. The period of sleep was significantly longer post-treating, and the habitual sleep efficiency was considerably higher, and sleep disturbance was significantly lower than before in the test group. Sleep drug use and daytime dysfunction after treating in the test group significantly improved the sleep effect. Changes in the Sociality Scale, Environmental Change Scale, and Quality of Life Scale significantly improved in the test group. The quality of life for 14 items in the test group was significantly correlated. Daytime drowsiness, depression, and anxiety scale changes were significantly improved in the test group. According to the predictive survey, the subjects felt warmth in their body and comfort in mind during and after using loess bedding and evaluated that sleep quality was good. Conclusions: The overall quality of life in the test group increased using loess bedding.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.311-316
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• 2020

The purpose of this study is to compare fatigue, stress and quality of sleep between good sleep quality and poor sleep quality. Fatigue, stress and quality of sleep were assessed using three questionnaires; fatigue severity scale(FSS), Perceived stress scale(PSS), and Pittsburgh sleep quality index(PSQL). As a result of the study, the higher stress(22.2 vs. 19.0, p=.000) and poorer quality of sleep(11.2 vs. 5.7, p=.000) were observed between good sleep quality and poor sleep quality groups. Our finding show that time of going to bed and stress level influenced quality of sleep.

• Sleep Medicine and Psychophysiology
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• v.24 no.1
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• pp.12-18
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• 2017

Adequate amount and quality of sleep are important for metabolic control in patients with type 2 diabetes. Too short or too long sleep time disrupts glycemic control in both prediabetes and type 2 diabetic patients. Circadian misalignment such as shift work is also associated with an increased risk of developing type 2 diabetes. Clinicians should pay attention to the sleep problems and circadian patterns of patients. However, the pathophysiologic mechanism of the association between sleep and diabetes is likely to be complex and bidirectional. The underlying mechanism remains poorly understood, and further research is warranted.

• Journal of Digital Convergence
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• v.18 no.11
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• pp.387-394
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• 2020

The purpose of this study is to identify walking time, self-efficacy for exercise, sleep quality and depression in order to confirm the relationship between college students' activity level and psychological index. The research method is a cross-sectional descriptive survey of college students. The subjects of this study were 135 students enrolled in colleges in Gyeongbuk. Self-efficacy for exercise was higher than the average, and walking time was about 1.7 hours per day on average, walking less than 2 hours. Sleep quality was most of them had problems with their sleep quality (71.9%). Depression was about half of the students showed a tendency to be depressed (49.6%). It was found that there was a correlation between self-efficacy and depression for exercise (p=.012). This study can be used as basic data for the development of programs to increase physical activity and improve psychological index of college students in the future.