• Journal of agricultural medicine and community health
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• v.38 no.4
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• pp.229-242
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• 2013

Objectives: The objective of this study was to identify the influence of shift work on sleep quality, daytime sleepiness, and perceived errors during nursing work among hospital nurses. Methods: The study subjects were 209 hospital nurses working in two general hospitals in South Korea. The data were collected through self-administered questionnaires in May 2013. Sleep quality was measured using Korea Pittsburgh Sleep Quality Index (PSQI-K), daytime sleepiness was measured using Epworth Sleepiness Scale (ESS), and perceived errors in past 6 months during nursing duty hours with the tool developed in this study. Results: The sleep quality was significantly worse among rotating shift nurses when compared to fixed day duty nurses. However, the odds ratio (OR) of 1.92 [95% confidence interval(CI): 0.58-6.37] adjusted for sociodemographic variables, health behaviors, and working environment in logistic regression was not significant. There was no significant difference in the daytime sleepiness between rotating shift nurses and fixed day duty nurses in both simple and multivariable analyses. There were significantly more perceived errors in rotating shift nurses than fixed day duty nurses. However, the OR of 1.26 (95% CI: 0.38-4.21) adjusted for sociodemographic variables, health behaviors, working environment, sleep quality, and daytime sleepiness in logistic regression was not significant. Depression (OR=3.31, 95% CI: 1.11-9.84) and daytime sleepiness(OR=1.18, 95% CI: 1.07-1.30) were significantly associated with perceived errors in logistic regression. Conclusion: This study suggested shift work among hospital nurses had no independent influence of sleep quality, daytime sleepiness, and perceived errors. However, daytime sleepiness had independent influence of perceived errors. More studies are warranted to achieve more reliable conclusion.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.2
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• pp.119-127
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• 2020

According to previous studies, an impaired pulmonary function is associated with arterial stiffness (AS). The pulse pressure (PP) is an important predictor of AS, but the association of an impaired pulmonary function with the PP is unclear. Therefore, this study assessed the associations between the PP and the predicted forced vital capacity (predicted FVC) and predicted forced expiratory volume in one second (predicted FEV₁) in Korean non-smoking adults. The data obtained from 6,857 adults during the 2013~2015 Korean National Health and Nutrition Examination Survey were analyzed. After adjusting for the related variables, the ORs of restrictive pulmonary disease (RPD, the predicted FVC<80.0% with FEV₁/FVC≥70.0%) using the normal PP group (PP≤60 mmHg) as a reference group was significant for the high PP group (PP>60 mmHg; 1.337 [95% confidence interval (CI), 1.049~1.703]). In addition, the ORs of obstructive pulmonary disease (OPD, FEV₁/FVC<70.0%) using the normal PP group as a reference group were significant for the high PP group (1.339 [95% CI, 1.093~1.642]). In conclusion, a high PP is positively associated with both RPD and OPD in Korean non-smoking adults.

• Journal of dental hygiene science
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• v.16 no.2
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• pp.165-175
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• 2016

Health behavior is one component of life style and is defined as behaviors performed by a person to protect, promote, or maintain the their health. General health behavior habits include not smoking, weight management, moderate drinking, regular exercise. The aim of this study was to analyze the relationship between toothbrushing and general health behaviors in 1,013 adults using data from the 2008 Daejeon Health Promotion Survey. Results showed no significant difference by region in general health behavior and toothbrushing. Smoking, alcohol consumption and toothbrushing frequency were related to sex, age, monthly income, occupation, and the degree of obesity. The predictoers of toothbrushing more than a day by losistic regression were female sex (vs. male, OR 1.88, 95% CI 1.20~2.95), age ${\geq}65$ years (vs. twenties, OR 0.51, 95% CI 0.26~0.99), monthly income 2 miillions Korean Won (KRW) to 3 millions KRW (vs. <2 million won, OR 1.58, 95% CI 1.04~2.42), white collar (vs. self-employment, OR 2.74, 95% CI 1.62~4.64), and regular exercise (vs. never, OR 1.60, 95% CI 1.21~2.11). We recommend the independent administration of oral health promotion programs focusing on aged and vulnerable social group because general health behaviors except regular exercise were not related to toothbrushing frequency.

• Economic and Environmental Geology
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• v.52 no.1
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• pp.37-48
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• 2019

In geological $CO_2$ sequestration, the behavior of $CO_2$ within a reservoir can be characterized as two-phase flow in a porous media. For two phase flow, these processes include drainage, when a wetting fluid is displaced by a non-wetting fluid and imbibition, when a non-wetting fluid is displaced by a wetting fluid. In $CO_2$ sequestration, an understanding of drainage and imbibition processes and the resulting NW phase residual trapping are of critical importance to evaluate the impacts and efficiencies of these displacement process. This study aimed to observe migration and residual trapping of immiscible fluids in porous media via cyclic injection of drainage-imbibition. For this purpose, cyclic injection experiments by applying n-hexane and deionized water used as proxy fluid of $scCO_2$ and pore water were conducted in the two dimensional micromodel. The images from experiment were used to estimate the saturation and observed distribution of n-hexane and deionized water over the course drainage-imbibition cycles. Experimental results showed that n-hexane and deionized water are trapped by wettability, capillarity, dead end zone, entrapment and bypassing during $1^{st}$ drainage-imbibition cycle. Also, as cyclic injection proceeds, the flow path is simplified around the main flow path in the micromodel, and the saturation of injection fluid converges to remain constant. Experimental observation results can be used to predict the migration and distribution of $CO_2$ and pore water by reservoir environmental conditions and drainage-imbibition cycles.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.661-667
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• 2005

In this paper, we propose a new hybrid genetic algorithm for sequential ordering problem (SOP). In the proposed genetic algorithm, the Voronoi quantized crossover (VQX) is used as a crossover operator and the path-preserving 3-Opt is used as a local search heuristic. VQX is a crossotver operator that uses the epistasis information of given problem instance. Since it is a crossover proposed originally for the traveling salesman problem (TSP), its application to SOP requires considerable modification. In this study, we appropriately modify VQX for SOP, and develop three algorithms, required in the modified VQX, named Feasible solution Generation Algorithm, Precedence Cycle Decomposition Algorithm, and Genic Distance Assignment Method. The results of the tests on SOP instances obtained from TSPLIB and ZIB-MP-Testdata show that the proposed genetic algorithm outperforms other genetic algorithms in stability and solution quality.

• Journal of Korean Society of Transportation
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• v.21 no.4
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• pp.67-77
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• 2003

The purpose of this study is to provide the criteria for implementing unprotected left turn at intersections with variation of traffic volume on a cross road approach. Using Transyt-7F model, the delays calculated from permissive and protected left turn signal system were compared by gradually increasing the left turn volume for a certain opposing through volume up to the volume limits to which permissive left turn is more effective, Average stopped delay of the intersection was used as the measure of effectiveness in this study. The major conclusions are (1) the lighter the traffic gets in a cross road, the more the allowable left turn volume increases. The allowable left turn volume when the ratio of cross traffic to the concerned approach traffic is 0.6 appears about 50% more than the volume when the ratio is 1.0. (2) Comparing to the criteria of the manual of traffic safety facility, the results when the traffic ratio is 0.6 seem to be most similar the criteria of manual and the results when the traffic ratio are 0.8 and 1.0 appears to be lower than the criteria of manual. (3) The possible amount of making a left turn that is inversely proportional to the opposing through traffic, decreases as the number of opposing through lanes increases. The products of volume need to be used as the criteria of permissive left turn with considerable cautions because of its low consistency.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.4
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• pp.1-9
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• 2012

This study deals with the operation effectiveness of roundabout. The objective of this study was to analyze the operational effectiveness of roundabout based on the operation of pedestrian signal. For pursuing the above, VISSIM was as a traffic simulation program. this study gives particular attention to analyzing the 1,680 scenarios by operation of Pedestrian Signal(7 cases), roundabout type(2 cases), pedestrian volume(8 cases) and entering volume(15 cases). The main results analyzed are as follows. First, the operational effectiveness analyzed by 2 type of 4-legged 1-lane roundabout and 6 type of 4-legged 2-lane were evaluated to be better than that by the others type. Second, the average delay time analyzed by operation of pedestrian signal were evaluated to be less than that by unsignalized pedestrian crossing. Finally, the average delay time analyzed by pedestrian crossing were decreased 8.18% than that by staggered pedestrian crossing in 4-legged 1-lane. However, the average delay time analyzed by staggered pedestrian crossing were evaluated to be decreased 36.53% than that by pedestrian crossing in 4-legged 2-lane.

• 한국도로학회지:도로
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• v.11 no.3
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• pp.55-59
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• 2009

• The Journal of Engineering Geology
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• v.31 no.4
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• pp.507-522
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• 2021

Specific survey objectives often cannot be met using only one geophysical method, as each method's results are influenced by the specific physical properties of subsurface materials. In particular, areas susceptible to geological hazards require investigation using more than one method in order to reduce risks to life and property. Instead of analyzing the results from each method separately, this work develops a four-quadrant criterion for classifying areas of levees as safe or weak. The assessment is based on statistically determined thresholds of seismic velocity (P-wave velocity from seismic refraction and S-wave velocity from multichannel analysis of surface waves) and electrical resistivity. Thresholds are determined by subtracting the standard deviation from the mean during performance testing of this correlation technique applied to model data of four horizontal and inclined fracture zones. Compared with results from the crossplot of resistivity and P-wave velocity, crossplot analysis using resistivity and S-wave velocity data provides more reliable information on the soil type, ground stiffness, and lithological characteristics of the levee system. A loose and sandy zone (represented by low S-wave velocity and high resistivity) falling within the second quadrant is interpreted to be a weak zone. This interpretation is well supported by the N values from standard penetrating test for the central core.

• Journal of radiological science and technology
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• v.31 no.3
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• pp.259-266
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• 2008

Objective : The purpose of this study was to examine the relationship between bone mineral density (BMD) and the metabolic syndrome. Method : We conducted a cross-sectional study of 1204 adults(males: 364 females: 840) in a general hospital health promotion center. They were grouped into the normal and lower BMD group according to bone loss(osteopenia, osteoporosis), as determined by duel energy X-ray absorptiometery(DEXA). We analyzed the association between BMD and metabolic syndrome by multiple logistic regression analysis. After adjustment for age, weight, alcohol intake, smoking, regular exercise, regular intake of meals, and menopausal status, odds ratios for the prevalence of the metabolic syndrome by gender were calculated for lower BMD. Results : After adjustment for the effect of potential covariates, the prevalence of metabolic syndrome was associated with bone loss in men(p<0.001). If the odds ratio of normal group is 1.00, then that of the lower BMD group is 3.07(95% CI=1.83-5.16). The prevalence of metabolic alterations fitting the criteria of metabolic syndrome was significantly decreased in High BMI, Low HDL in men and in High BMI in women(p<0.05). Conclusions : This study shows that BMD was associated with metabolic syndrome. Further studies needed to obtain evidence concerning the association between BMD and metabolic syndrome.