• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.200-206
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• 1998

The effect of surface tension and viscosity of polymer solution on the thickness of water casting membranes was studied. Spreading of polymer solutions on water surface was governed by the surface tension and viscosity of the polymer solution. The thickness of water casting membrane was affected by these two factors. The properties, mentioned above, were proportional to the polymer concentration. The order of magnitude in surface tension was PVC>PS>CA and that of viscosity was CA>PS>PVC. The difference of surface tension between water and polymer solution acts as driving force for spreading of polymer solution, but the viscosity as resistance. The thickness of polymeric membrane prepared by water casting was PS>CA>PVC. The order of membrane thickness was not as same as that of surface tension. This phenomena were due to the viscosity which acts as more effective spreading resistance than the surface tension.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7013-7020
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• 2015

The purpose of the study was to explore quality of sleep, fatigue and job stress and to identify related factors in airlines international flight attendants. The major findings of this study were as follows: 1) Significant factors of job stress by Subject Characteristics were gender(t=-4.14, p<.001), position(F=3.47, p=.011), monthly flight time(F=3.70, p=.028), health supplements(t=3.66, p<.001), sleeping pills(t=4.27, p<.001). 2) A statistically significant relationship between quality of sleep(r=-.57, p<.001), fatigue(r=.61, p<.001) and job stress. 3) The results of the regression analyses showed that fatigue, sleeping pills, gender, quality of sleep were statistically significant in predicting airlines international flight attendants' job stress. The result of this review provide a better understanding of quality of sleep, fatigue and job stress in airlines international flight attendants.

• Journal of the Korea Convergence Society
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• v.8 no.3
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• pp.141-150
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• 2017

The purpose of this study was to identify relationship among the depression, social support and quality of sleep in elderly insomnia patients. A total of 143 patients with insomnia diagnosed according to DSM-IV criteria. Quality of sleep, depression, and social support were measured using a self structured questionnaire and participant's medical records were reviewed for obtaining their clinical information. Quality of sleep was positively associated with depression(r=.255, p<.05), and negative correlation with social support(r=-.270, p<.001). The significant factors for quality of sleep were information support(${\beta}=-0.406$, p<.05) and affectionate support(${\beta}=-0.525$, p<.05). These factors explained 13.2% of the variance in quality of sleep. The elderly patients suffering the insomnia need the nursing interventions considering information support and affectionate support in order to improve sleep quality.

• Journal of the Korean Geotechnical Society
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• v.28 no.6
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• pp.63-70
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• 2012

The authors discuss the effect of hydraulic conductivity on the suction profile and stability of a typical cut-slope subjected to low intensity rainfall. The initial suction value above the ground table in the unsaturated zone is assumed to be 15 kPa. The uncoupled approach of finite element and limit equilibrium method is used to evaluate the stability of the cut-slope at different elapsed times of rainfall. The finite element seepage analysis shows that the soil in the unsaturated zone always remains unsaturated during the course of low intensity rainfall. Furthermore, the slope stability remains practically unchanged so long as the wetting front remains in the unsaturated zone but it decreases noticeably when the wetting front reaches and elevates the ground water table level.

• Sleep Medicine and Psychophysiology
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• v.4 no.1
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• pp.29-38
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• 1997

Dementia is defined as a syndrome which is characterized by various impairments in cognitive functions, especially memory function. Most of the diagnostic criteria for dementia include memory impairment as on essential feature. Memory decline can be present as a consequence of the aging process. But it does not cause significant distress or impairment in social and occupational functionings while dementiadoes. Depression may also be associated with memory impairment. However, unlike dementia, depression dose not cause decrease in delayed verbal learning and recognition memory. In dementia, different features of memory impairment may be present depending on the involved area. Memory impairment in cortical dementia is affected by the disturbance of encoding of information and memory consolidation, while memory imparnene in subcortical denentiy is affected by the disturbance of retrieval in subcortical dementia.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.546-559
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• 2016

This study was conducted to analyze the relationship between sleep quality, stress response, physical activity and sleep hygiene in shift work nurses and identify factors influencing sleep quality. The participants were 168 shift nurses from university hospitals and general hospitals located in C city, Gyeongnam. Data were collected from March 25 to 31, 2016. The study instrument use to the Pittsburgh Sleep Quality Index, Stress Response Inventory, Korean version of the International Physical Activity Questionnaire Short Form and Sleep Hygiene Scale. Date were analyzed by frequency, t-test, ANOVA, Pearson's correlation and hierarchical multiple regression using SPSS/win18.0. The sleep quality index was 7.35 (range 0-21), stress response was 2.20 (range 1-5), physical activity was 3986MET-min/week, and sleep hygiene was 2.73 (range 1-6 points). There were significant differences in sleep quality according to shift work experience, health status and circadian rhythm type. Factors influencing sleep quality included shift work experience, sleep hygiene, stress response and physical activity, which together explained 40% of the total variance of sleep quality. Therefore, it is recommended that sleep hygiene education be implemented as a strategy to reduce stress response, and that shift work nurses engage in a moderate level of physical activity to improve their sleep quality.

• Journal of Ocean Engineering and Technology
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• v.10 no.3
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• pp.74-82
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• 1996

수면상에 떠있는 2차원 물체에 작용하는 시간평균 표류력 및 표류모오멘트를 비점성 선형 포텐셜 이론을 사용하여 계산하는 방법에 대하여 검토하였다. 부유체 접수면상의 압력을 직접적분하여 구한 수평방향 표류력이 특정주파수 부근에서 음의 값을 보이고 있다. 이는 무한원방에서의 에너지 보전방법에 의한 표류력이 항상 양의 값을 취한다는 기존 이론과 상이하다. 본 논문에서, 이러한 차이가 부유체의 횡요 및 상하동요에 기인한 복원력의 성분과 횡요와의 연성효과에 의하여 발생하였음을 규명하였다. 이는 횡요가 있는 경우, 표류력을 산출하는 기존의 무한원방 방법에 결함이 있음을 보이고 있다. 이에 반하여 기존의 접수면압력 직접적방법은 부유체에 작용하는 시간평균 표류력 및 표류모오멘트를 모든 주파수에 대하여 정확하게 산출한다고 결론지울 수 있다.

• Sleep Medicine and Psychophysiology
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• v.16 no.2
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• pp.65-73
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• 2009

Objectives: The purpose of this study was to assess the clinical and polysomnographic characteristics of Korean patients with obstructive sleep apnea syndrome (OSAS), especially in relation to differences due to age and gender. Methods: All subjects were consecutive patients who were proven to have OSAS with nocturnal polysomnography. They were interviewed with a structured interview format including sociodemographic information, past medical history, medication, and sleep-related history. Simultaneously, they were also given Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS) to answer in order to check subjective sleep quality and subjective sleepiness. Results: Mean age of the 308 subjects was $49.5{\pm}$13.3 years, with 77.6% of the subjects being males and 22.4% of the subjects being females. The aging effects on the sleep architecture in Korean OSAS corresponded with normal aging, but with the effect of OSAS itself superimposed, the extent of aging effects was more marked than that of normal aging. The severity of Korean patients of OSAS was not correlated with age. When divided into age subgroups, significant correlation was found between RDI and BMI in patients of each subgroup of those in the 4th to 7th decades. The oldest subgroup (>70 years) described their subjective sleep quality as poorer than any other age subgroups, despite of less subjective drowsiness. The severity of OSAS and the change of sleep architecture of male subjects turned out to be severer than those of female ones. The female/male ratio of the subjects tended to increase with aging. Conclusions: The aging effect on the sleep architecture in Korean OSAS seems to be a mixture of the changes by normal aging and sleep disorder per se. The severity of OSAS was not correlated with age, but highly correlated with BMI. The severity of OSAS and the change of sleep architecture of male patients were severer than those of female ones.

• The Journal of Korean society of community based occupational therapy
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• v.7 no.3
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• pp.35-42
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• 2017

Objective : The purposes of this study are to examine the correlations among work ability and sleep quality in bus driver and to find the factors affecting work ability. Methods : The participants were 120 inpatients with bus driver. The Work Ability Index(WAI) was used for measuring work ability and the Pittsburgh Sleep Quality Index (PSQI) was utilized to measure sleep quality. The relationships among the variables were examined with Pearson correlation coefficients. And the stepwise multiple regression analysis were performed to identify the predictive variables that explain changes of work ability. Results : As a result of analyzing correlation of variables affecting work ability, there was negative correlation in contact sleep quality(p<.001) and working hours(p<.001). Finally, Work ability was identified as a factor that explains 48.2% of change in sleep quality(p<.001) and working hours(p<.01). Conclusion : It was found that intimacy of bus driver was a major variable to affect work ability. The sleep quality and working hours should be considered as a way to improve the bus driver work ability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.562-570
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• 2019

The purpose of this study was to identify the factors influencing the quality of sleep in breast cancer patients receiving chemotherapy in the outpatient settings. The data were collected from 203 patients with breast cancer receiving chemotherapy in the outpatient settings at one tertiary hospital in B City. Stress, fatigue and depression were negatively correlated with quality of sleep (r=-.369, p=.001; r=-.565, p=.001; r=-.526, p=.001, respectively). Fatigue(${\beta}=-.387$, p<.001) was one of the biggest impact factors on quality of sleep which explained 31.6% of the variance of the sleep quality, followed by the experience of sleep disturbances prior to the diagnosis of breast cancer(${\beta}=-.178$, p<.002) and depression(${\beta}=-.231$, p<.004). In total, all of the antecedent variables explained significantly 37.4% of the variance of the sleep quality. Thus, in order to improve the quality of sleep, integrative nursing interventions need to be developed to reduce fatigue and depression among them, including an proactive system to screen out the patients with the experience of sleep disturbances prior to the diagnosis with breast cancer and to provide adequate pharmacological and/or non-pharmacological sleep interventions prior to the chemotherapy.