• Journal of Korean Public Health Nursing
• /
• v.16 no.2
• /
• pp.271-284
• /
• 2002

This study was to provide basic materials to help reduce the fatigue by analyzing what effective factor the fatigue of hospital nurses in Gwangju and Jeonnam region. and what causes their fatigue. This descriptive research by Questionaires includes two hospitals in Gwangju. and seven hospitals in Jeonnam region, total 9 hospitals sampled at convenience sampling. The periods of collecting data was from Jul.22, 2002 to Jul. 30, 2002. Multidimensional Fatigue Scale; MFS, developed by Jang Se-Jin(2000) was taken to measure the fatigue. All collected materials were got the statistics by SAS for Windows Release 8.01. The result of this study was as follows. 1. This study included total 740 nurses, whose age ranged from 22 to 50; 30 years old by average. Nurses fatigue mean score was 90.24 (the scope by the measuring instrument is 19-133). Nurses at University Hospitals marked 92.36 and those at General Hospitals marked 87.91 in the mean score of fatigue. 2. They kept tired at work, and felt more tired while working at computer in the hospital. 3. The part of body in which they felt fatigue was the calf and $feet(36.6\%)$, the shoulders and back of the $neck(30.7\%)$, and the whole $body(10.8\%)$ and the reason that they felt tired at work was mental $stress(33.0\%)$, overworking(25.2\%)$, and irregular working $conditions(14.7\%)$ in order. 4. The solution to their fatigue at work appeared nothing by $50.1\%$, and the way of releasing fatigue after work indicated getting some $sleep(30.8\%)$, and taking a bath or a $shower(21.7\%)$ in order. 5. The degree of fatigue depending on whether they were satisfied with their pay and labor condition appeared low: and when they were satisfied with doctors. and when they were getting on well with caregivers. 6. The effective factor of the degree of fatigue appeared: the influence that fatigue in the hospital makes on daily life was $10.6\%$, the cause of fatigue at work, $9.3\%$, time of fatigue at work, $7.8\%$, the relationship with caregivers, $5.3\%$. and these explanatory$(R^2)$ variables.$33\%$. To conclude. the degree of nurses' fatigue appeared high. and it was higher in nurses at University Hospitals than in ones at General Hospitals. In addition, the influence that fatigue from the hospitals made on daily life was the most explanatory.

• Journal of Environmental Science International
• /
• v.18 no.10
• /
• pp.1135-1141
• /
• 2009

Carrots (Daucus carota L.) are consumed as an important dietary source of provitamin A including $\beta$-carotene, $\alpha$-carotene and lutein. An HPLC method was applied to determine the content of the carotenoid composition in carrot cutivars cultivated in Korea. HPLC analyses were carried out with five carrot cultivars (Socheon-5-chon, Hongsim-5-chon, Myeongju-5-chon, Seonhongbom-5-chon and Betarich) sown at April, 2007 and six cultivars (Yeoreum-5-chon, Hanyeoreum-5-chon, Sinheukjeon-5-chon, Bibariheukjeon, Manina and Betarich) sown at August of the same year. In general, the former varieties are not used for the sowing at summer because of their bolting (growth of floral axis). The former and the latter carrots were harvested after 110 and 96 days from seeding, respectively, and the carotenoids were extracted with acetone after freeze-drying. The amount of $\alpha$-carotene ($117.7{\sim}205.3\;{\mu}g/g{\cdot}DW$) was similar to that of $\beta$-carotene ($113.1{\sim}189.6\;{\mu}g/g{\cdot}DW$) for the carrot cultivars sown at spring, while the content ($46.2{\sim}71.1\;{\mu}g/g{\cdot}DW$) was about a half of $\beta$-carotene content ($92.5{\sim}140.2\;{\mu}g/g{\cdot}DW$) for the latter cultivars. In addition, the average content of lutein ($25.2\;{\mu}g/g{\cdot}DW$) in the former cultivars was eight times higher than that in the latter cultivars ($3.1\;{\mu}g/g{\cdot}DW$). Among the spring cultivation types, Socheon-5-chon and Myeongju-5-chon showed higher amount of $\alpha$-carotene and $\beta$-carotene, while the higher amount was determined in Yeoreum-5-chon and Sinheukjeon-5-chon among the autumn cultivation types. Validation of the HPLC-DAD method showed good linearity ($r^2$ > 0.997) of the three compounds analyzed in a wide concentration range ($0.025{\sim}20\;{\mu}g/ml$). The R.S.D. values for intra-day and inter-day precision were less than 19.2% and the mean recovery of each compound was 85.4~104.7%.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.3
• /
• pp.965-974
• /
• 2013

Multiple debris flows occurred on July 27, 2012 in Mt. Umyeon, which resulted in 16 casualties and severe property demage. Accurate reproducing of the propagation and deposition of debris flow is essential for mitigating these disasters. Through applying FLO-2D model to these debris flows and comparing the results with field observations, we seek to evaluate the performance of the model and to analyse the rheological model parameters. Representative yield stress and dynamic viscosity back-calculated for the debris flows in the northern side of Mt. Umyeon are 1022 Pa and 652 $Pa{\cdot}s$, respectively. Numerical results obtained using these parameters reveal that deposition areas of debris flows in Raemian and Shindong-A regions are well reproduced in 63-85% agreement with the field observations. However, the propagation velocities of the flows are significantly underestimated, which is attributable to the inherent limitations of the model that can't take the entrainment of bed material and surface water into account. The debris flow deposition computed in Hyeongchon region where the entrainment is not significant appears to be in very good agreement with the field observation. The sensitivity study of the numerical results on model parameters shows that both sediment volume concentration and roughness coefficient significantly affect the flow thickness and velocity, which underscores the importance of careful selection of these model parameters in FLO-2D modeling.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.12
• /
• pp.614-621
• /
• 2019

A generalized laminated composite beam element is presented for the flexural and buckling analysis of laminated composite beams with double and single symmetric cross-sections. Based on shear-deformable beam theory, the present beam model accounts for transverse shear and warping deformations, as well as all coupling terms caused by material anisotropy. The plane stress and plane strain assumptions were used along with the cross-sectional stiffness coefficients obtained from the analytical technique for different cross-sections. Two types of one-dimensional beam elements with seven degrees-of-freedom per node, including warping deformation, i.e., three-node and four-node elements, are proposed to predict the flexural behavior of symmetric or anti-symmetric laminated beams. To alleviate the shear-locking problem, a reduced integration scheme was employed in this study. The buckling load of laminated composite beams under axial compression was then calculated using the derived geometric block stiffness. To demonstrate the accuracy and efficiency of the proposed beam elements, the results based on three-node beam element were compared with those of other researchers and ABAQUS finite elements. The effects of coupling and shear deformation, support conditions, load forms, span-to-height ratio, lamination architecture on the flexural response, and buckling load of composite beams were investigated. The convergence of two different beam elements was also performed.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.21 no.4
• /
• pp.398-405
• /
• 2001

The rivet joint has typical structural feature that can be initiation site for the fatigue crack due to the combination of local stress concentration around rivet hole and the moisture trapping. From a viewpoint of structural assurance, it is crucial to evaluate the size of crack around the rivet holes by appropriate nondestructive evaluation techniques. Lamb wave that is one of guided waves, offers a more efficient tool for nondestructive inspection of plates. The neural network that is considered to be the most suitable for pattern recognition has been used by researchers in NDE field to classify different types of flaws and flaw sizes. In this study, clack size evaluation around the rivet hole using the neural network based on the back-propagation algorithm has been tarried out by extracting some features from the ultrasonic Lamb wave for A12024-T3 skin panel of aircraft. Special attention was paid to reduce the coupling effect between the transducer and the specimen by extracting some features related to time md frequency component data in ultrasonic waveform. It was demonstrated clearly that features extracted from the time and frequency domain data of Lamb wave signal were very useful to determine crack size initiated from rivet hole through neural network.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.6 no.3
• /
• pp.201-209
• /
• 2002

Crib wall system is one of segmental crib type wall. Crib walls are constructed from separate members with no bonds between them other than frictional. The wall units are divide into two main types termed headers and stretchers. The headers run from the front to the back of the wall, perpendicular to the wall face. The cells are created by forming a grid by stacking individual wall components known as headers and stretchers. The body of wall consists of a system of open cell which are filled with a granular material. The design of crib retaining wall is usually based on conventional design methods derived from Rankine and Coulomb theory so that is able to resist the thrust of soil behind it, because it may be assumed that the wall acts as a rigid body. However, deformation characteristics of crib walls cannot be assumed as monolithic. They consist of individual members which have been stacked to creat a three dimensional grid. Therefore, the segmental grid allows relative movement between the individual member within the wall. The three dimensional flexible grid leads to stress distribution by interaction behavior between soil and crib wall. Therefore, in this study, in order to analysis the trends of deflection of crib wall system, new numerical models based on the results of Brandl's full scale test are introduced for design concept.

• Design & Manufacturing
• /
• v.12 no.1
• /
• pp.52-57
• /
• 2018

With the recent strengthening of environmental regulations and the need for cost reduction, excavators, a type of construction equipment, are being miniaturized while components are being developed in consideration of stability. In the case of excavator press parts, mainly high-strength steel sheets are being used to enhance stability and reduce weight. However, in the case of high-strength materials, there is a need to research product forming methods to reduce Springback in defects arising in parts assembly due to Springback that result from the internal residual stress that occurs in press forming being released after product forming. Accordingly, regarding the tank cover, an excavator press-forming part, this study selected a method to reduce distortion through analysis of the Springback occurrence rate and Springback causes through a forming analysis. A forming analysis was conducted for the Springback of the tank cover. Deformations of 13.714 mm in the upper part and 6.244 mm in the inner part of the product occurred, while wrinkles occurred on the sides of the product due to uneven thickness. A forming analysis was conducted for the major shapes of the product to investigate the causes of Springback. Distortion deformation due to the bead in the center of the product was confirmed to be a large factor. A Springback reduction method of correcting uneven thickness in the product sides, a Springback reduction method of removing the bead, and a correction method of restriking after the final forming were used in a forming analysis to determine the degree of Springback reduction. For the forming method to correct uneven thickness in the sides, deformation was reduced by 12% in the upper side compared to the existing model, but deformation in the inner side increased by 1%. For the restriking forming method, deformation decreased by 25% in the upper side and 13% in the inner side. For the bead removal method, deformation decreased by 28% in the upper side and 13% in the inner side, the largest Springback correction results. This indicates that the bead has a large affect on Springback.

• The Journal of Korean Physical Therapy
• /
• v.12 no.1
• /
• pp.101-112
• /
• 2000

The aim of this study is to compared the cerebral palsy children with normal children in the exercise and cardio vascular ability after this study as the fundamental data fer mating programs for the cerebral palsy children. The test of this study is about twenty girls, the control group of the normal children(n=10) and the experiment group of cerebral palsy children(n=10). They were studied in four aspects which were the anthropometry, the medical check in the rest, the physical fitness or exercise roads test and the change of the target heart rate during exercise. The result were as follows : 1. The characteristic of the physical type : The control group is higher than the experiment group in the standing height and the body weight but their's little difference between them (p<0.05). The control group is lower than the experiment group in the body fat. 2. The characteristic of the medical check in the rest : The control group is higher than the experiment group in the vital capacity and flood expiratoryvolume one second. The control group is higher that the experiment group in the blood pressure of systolic and Diastolic. There's little difference between them(p<0.01). The control is lower than the experiment group in the heart pulse rate. There's little difference between them(p<0.005). 3. The characteristic of basic physical strength evaluation : The experiment group is the lowest dynamic muscular endurance, balance, agility and endurance which need to move the body with weight. The control group is much higher than the experiment group in the flexibility and muscle strength(Back strength). There's no difference between them(p<0.05). 4. The characteristics of the exercise stress last : The control group is higher than the experiment group in the endurance, the maximum of oxygen intake, endurance level and the out take of calory. There's little difference between them(p<0.01). 5. The characteristic of the change of the target heart rate during exercise : The control group is lower than the experiment group exchange of target heart rate, There's no difference them.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.6
• /
• pp.1677-1685
• /
• 2014

Short discrete fibers compounded with concrete can enhance the tensile resistance and ductility of concrete. Recently, the effectiveness of the reinforcement has increased according to the increasing length of steel fiber. However, the lengthening of steel fiber requires reducing the ratio of the fiber content to remain the workability and quality of concrete. Thus, the present study evaluated the flexural performance of fiber reinforced concrete with less than l.0% fiber volume ratios of steel fiber, 30mm and 60mm long, and polypropylene fiber, being evaluated as a good reinforcing material with chemical stability, long-term durability, and cost effectiveness. Concrete with more than 0.25% steel and 0.5% polypropylene fibers improved the brittle failure of concrete after reaching cracking strength. Concrete reinforced with polypropylene exhibited deflection-softening behavior, but that with more than 0.5% polypropylene delayed stress reduction and recovered flexural strength by 60 to 80% after cracking strength. In conclusion, concrete reinforced with more than 0.75% polypropylene could improve structural flexural performance. In particular, energy absorption capacity of reinforced concrete with 1.0% polypropylene fiber was similar to that with 0.5% and 0.7% steel fibers.

• Journal of the Korean Society of Safety
• /
• v.25 no.6
• /
• pp.169-179
• /
• 2010

The aim of this study was to investigate occupational and individual risk factors and working conditions in relation to musculoskeletal symptoms in street cleaners. Investigation was conducted through a survey of 395 male street cleaners employed by the government office in Seoul, Gyeonggi and Chung-Nam from July to August of 2009. The control group was comprised of 143 male drivers and security guards. Risk factors for musculoskeletal symptoms in street cleaners were investigated by multiple logistic regression analysis and also evaluated ergonomic risk factors by assessing working conditions of 4 street cleaners. As a result of symptom questionnaires, all of the prevalent rates of musculoskeletal symptoms in street cleaners had significantly higher results than those of the control group(p<0.05). On binary logistic regression analysis of musculoskeletal symptoms, street cleaners showed significant higher odds ratio as 18.84(95%CI: 6.56-54.12) in the arm/elbow, 10.49(95%CI: 4.29-25.65) in the hand/wrist compared to the control group. Both absence of rest breaks and exposure to ergonomic risk factors showed to be important internal risk factors of musculoskeletal symptoms among street cleaners. The exposure levels of QEC(Quick exposures checklist) in street cleaners were revealed to be higher on the shoulder/arm, wrist/hand, and neck than back, or from stress. The findings appear to show that street cleaners were high-risk group of work-related musculoskeletal disorders. Therefore street cleaners require a holistic interventional strategy, including adequate arrangement of rest breaks, improvement of working tools and control of individual risk factors such as obesity and smoking.