• Journal of Korean Society of Disaster and Security
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• v.11 no.1
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• pp.31-38
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• 2018

The 99.1% of small dam and most of the levees in Korea are soil dam which can be constructed with lower cost and less effort compared with ones made of concrete. However, they are so vulnerable to overflow. Sudden collapses of these strucrues lead to increase flow rate rapidly, which may cause catastrophic problems in downstream regions. In this study, the experimental study on the collapse delay effect of riprap that was laid on slope of soil levee was carried out. A prismatic rectangular open channel was used and three different sizes of the riprap were installed on slope of a scaled earth dam. A new formula for the collapse time of the levee with the installation of riprap was presented, using the previous researches and the dimensional analysis. In this process, an unsteady flow condition was considered to derive the deviation time of the riprap. And additional experiments were conducted to understand the effect of reinforcement of riprap, and it was found that the reinforcement of riprap was more effective than twice sizing of intial riprap. If the collapse time is delayed, EAP (Emergency Action Plan) and forecasting can greatly reduce the degree of flood damage. Also, it will be meaningful that the results of this study are used for river design.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.6 no.2
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• pp.240-254
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• 1999

The purpose of this study was to investigate the effect of exercise therapy and relaxation therapy on catecholamine and heart rate in people in white color jobs and to determine this information the effectiveness of applied exercise therapy and relaxation therapy as a nursing intervention method for stress patients. The subjects were divided into an exercise therapy group, a relaxation therapy group, and control group and the research design was a nonequivalent control group pretest-post test design(exercise therapy : n= 12, relaxation therapy : n=12, control group, the group without any treatment in exercise on relaxation therapy : n=12), The subjects in the exercise therapy group were given a particular intensity for each kp during 30min, bicycle ergometer which is using an LX PE training system before & after 4weeks of training. The exercise therapy that was used was Astrard load method which tested absolute exercise load of heart rate before & after four weeks, and resting heart rate was tested for exercise and relaxation therapy before, after four weeks, and at eight weeks. The results of each kp & absolute exercise load were calculated with the target rate formula(maximal heart rate-rest heart rate) x exercise intensity(%) + rest heart rate so the subjects could continue 60-70% exercise intensity for exercise therapy over eight weeks. The relaxation therapy subjects were trained using a modified Jacobson's relaxation technique for eight weeks. The exercise and relaxation therapy were trained at the following intensity for eight weeks(3times/week, 30min/day) to see changes in catecholamine & heart rates. After eight weeks, statistical analysis of exercise & relaxation therapy were carried out Two-way ANOVA and multiple range test(SNK : Student Newman Keul) were used. The results are as follows : 1. The change of epinephrine & norepinephrine in the exercise therapy, relaxation therapy, and control group was statistically significant at the .05 level after four weeks & eight weeks. Also, exercise therapy was statistically significant at .05 level over that of the control group after 4weeks. 2. The change of heart rate in relaxation therapy was statistically significant at the .05 level, and was statistically significant at the .05 level over that of the exercise therapy and control group. In conclusion, it is obvious that exercise therapy and relaxation therapy should be one of the most effective stress treatment and desirable nursing interventions methods for job stress in people in white color jobs.

• Korean Journal of Adult Nursing
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• v.13 no.3
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• pp.373-384
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• 2001

The purpose of this study was to develop a DanJeon Breathing Exercise Program for health promotion and to examine the effects of a DanJeon Breathing Exercise Program on the physical and emotional health promotion of women in midlife. The design utilized for this study was quasi-experimental with a nonequivalent control group pretest-posttest design. This study was done between February 1 and July 4, 2000 and the subjects of the study were 40 women in midlife living in Seoul. There were 20 members in experimental group who participated in the DanJeon Breathing Exercise Program and 20 members in the control group who were chosen as matched to members of the experimental group according to age, education and religion. The DanJeon Breathing Exercise Program was carried out for 80 minutes a day, 3 times a week for 12 weeks. The percent of body fat, back strength, flexibility (trunk flexion), balance and vital capacity were measured using the Health Management System developed by the Korea Physical Science Institution. Blood tests were done at D infirmary for total cholesterol, and the atherogenic index was calculated using an established formula. The scores of anxiety and depression were measured by a questionnaire with 10 questions on anxiety and 13 questions on depression. It was developed from the Korean Manual of Symptoms-Checklist-90 revision. The collected data were processed using the SPSS PC program and analyzed using $\chi^2$-test and t-test. The result of this study are as follows : 1. The percent of body fat for the experimental group who participated in the DanJeon Breathing Exercise Program was lower than that of the control group. 2. The degree of back strength, flexibility (trunk flexion) and balance of the experimental group that participated in the DanJeon Breathing Exercise Program was higher than that of the control group. 3. The vital capacity of the experimental group that participated in the DanJeon Breathing Exercise Program was higher than that of the control group. 4. The total cholesterol level and atherogenic index of the experimental group that participated in the DanJeon Breathing Exercise Program were lower than those of the control group. 5. The scores for anxiety and depression in the experimental group that participated in the DanJeon Breathing Exercise Program were lower than those of the control group. In conclusion, DanJeon Breathing Exercise Program promotes the physical and emotional health of women in midlife. The DanJeon Breathing Exercise Program can be utilized as a nursing intervention for the promotion of health in women in midlife.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.4
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• pp.25-36
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• 1984

This paper checked up the safety criteria of the steel structural members by LRFD. And it calculated the resistance and load modulus for it by the proposed method, considering our circumstance, by establisting the taget relability index (${\beta}_0$), and compared their calculated modulus with the nominal safety factors of the road-bridge code and analyzed them. Uncertain quantity measurements fnr the resistance of the steel structural members and for the load effect are due to the method of the uncertain quantity analysis of the load and the resistance, of Galambos-Ravindra and SGST. The summary of the results is as follows: 1) Considering our circumstance, taget relibility index(${\beta}_0$) for current steel structural members are appropriate ${\beta}_0=3.5$. 2) Nominal resistance ${\Phi}^{\prime}$ of the strength design formula for 1) and nominal load modulus ${\gamma}_i^{\prime}$ are as follows; a) Both-sides support plate: ${\Phi}{^{\prime}}=0.75$, ${\gamma}_0{^{\prime}}=1.04$, ${\gamma}_L{^{\prime}}=2.08$ b) One-side support plate: ${\Phi}{^{\prime}}=0.82$, ${\gamma}_0{^{\prime}}=1.04$, ${\gamma}_L{^{\prime}}=2.11$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.71-76
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• 2018

Recently, various technologies have been developed for road facilities to reduce the load, some of which use technologies employing perforated plates for wind load reduction. Currently, there are no regulations concerning the drag coefficient of perforated plates for domestic road facilities. In the United States, the regulations regarding the drag coefficient of perforated plates in the 'Minimum design loads for buildings and other structures' were revised based on the studies of Letchford (2001) and Giannoulis (2012). In this study, a wind tunnel test was carried out to analyze the feasibility of applying regulations involving the perforated plates' drag coefficient. The results of the wind tunnel test and the drag coefficient used in the regulation were compared and analyzed. In addition, the reduction effect of the cross area of road signs calculated by applying the drag coefficient was analyzed. The results of the wind tunnel test and the value of the drag coefficient used in the regulation in the US were found to be very similar. Therefore, it was found that it is possible to apply the formula involving the drag coefficient of the perforated plate to the regulation and that the cross area of the perforated plate used for the post of the road sign is reduced by about 9.45% and that of the horizontal post by about 6.45%.

• Journal of Korean Society of Steel Construction
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• v.26 no.4
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• pp.323-334
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• 2014

In this paper, experimental program and associated numerical study were carried out to evaluate the fire resistance of unprotected concrete-filled rectangular steel tubular (CFT) columns subjected to the standard fire. The key testing parameters included the length effect, the load ratio, and the sectional dimensions of the CFT columns. Temperature distribution and axial deformation of the CFT column specimens were measured and analyzed. Rather early local buckling of steel tubes was observed in all the specimens. This caused subsequent load transfer from steel tube to concrete, and eventually triggered concrete crushing, or complete loss of the load bearing capacity of the column. This implies that the limit state of local buckling as well as overall flexural buckling should be incorporated in fire design procedure. As expected, the fire resistance time of specimen with higher load ratio consistently lessened. The prediction of fire resistance time of unprotected CFT columns based on the limiting steel temperature in current design codes or the formula proposed by previous studies is slightly conservative compared to the fire test results available. To establish the finite element analysis model that can be used to predict the thermal and structural behaviour of unprotected CFT columns in fire, the fully coupled thermal-stress analysis was also tried by using the commercial code ABAQUS. The numerical results showed a reasonable global correlation with the experimental results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.148-156
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• 2020

The paper is a summary of the results of the basic pullout test which is conducted to evaluate the anchorage capacity of high strength headed bars that is mechanical anchored vertically on steel fiber reinforced concrete members. The main experimental parameters are volume fraction of steel fiber, concrete strength, anchorage length, yield strength of headed bars, and shear reinforcement bar. Both sides of covering depth of the specimen are planned to double the diameter of the headed bars. The hinged point is placed at the position of each 1.5𝑙_dt and 0.7𝑙_dt around the headed bars, and the headed bars are drawn directly. As a result of pullout test experiment, concrete fracture and steel tensile rupture appear by experimental parameters. The compressive strength of concrete is 2.7~5.4% higher than that of steel fiber with the same parameters, while the pullout strength is 20.9~63.1% higher than that of steel fiber without the same parameters, which is evaluated to contribute greatly to the improvement of the anchorage capacity. The reinforcements of shear reinforcements parallel to the headed bars increased 1.7~7.7% pullout strength for steel fiber reinforced concrete, but the effect on the improvement of the anchorage capacity was not significant considering the increase in concrete strength. As with the details of this experiment, it is believed that the design formula for the anchorage length of KCI2017and KCI2012 are suitable for the mechanical development design of SD600 head bar that is perpendicular to the steel fiber reinforced concrete members.

• Food Engineering Progress
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• v.21 no.2
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• pp.167-173
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• 2017

Purple-fleshed potato powder (PFPP) was investigated to determine optimal mixing ratio with milk powder and dextrin to produce a ready-to-eat mashed potato powder. The rheological characteristics, color, and anthocyanin contents were studied at a different concentration of ingredients. The power-law model was applied to explain the mechanical spectra of mashed potatoes which represented the change in structure induced by different mixing ratios. Mixture design was used to obtain the experimental points used to establish the empirical models to describe the effects of each ingredient on the characteristic of the mashed potato. The results of mechanical spectra showed that both storage and loss moduli (G' and G'') were significantly influenced by PFPP and milk powder concentration. The power law parameters n' and n'' showed higher values for the mashed potato with a lower concentration of PFPP and a higher concentration of milk powder, which showed that the gel networks involved in the mashed potato were weaker. The optimum mixing ratio with the highest redness and anthocyanin content, while maintaining the rheological properties similar to the commercial mashed potato, was determined as PFPP:milk powder:dextrin = 90.49:4.86:4.65 (w/w). The proportions of PFPP and milk powder in the formulation significantly changed the characteristics of mashed potato, whereas no significant effect of dextrin was observed in this formulation.

• Journal of Korea Water Resources Association
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• v.34 no.1
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• pp.81-90
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• 2001

A dynamic flood frequency analysis model was proposed for the frequency analysis in ungaged catchment and applied to 6 subbasins in Pyungchang River basin. As the dynamic flood frequency model requires precipitation, rainfall loss system, and runoff analysis, we adopt the rectangular pulse model, the SCS formula, and the geomorphoclimatic IUH(GcIUH) for the application. Input data for the analysis was borrowed from the results of the statistical flood frequency analysis using L-moment method for the same catchment, and then the return period was estimated using the model. This result was also compared with the return period estimated from the statistical analysis. By comparing with the results from two cases, we found the dynamic flood frequency analysis gave higher estimates than those from statistical analysis for the whole subbasins. However, the dynamic flood frequency analysis model has a potential to be used for determining the design flood for small hydraulic structure in ungaged catchment because it uses only physical parameters for flood frequency analysis. And this model can be easily applicable to other watersheds as the scale effect is negligible.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.137-147
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• 2012

In the steel-free bridge concrete deck, steel straps are generally used instead of conventional steel rebar while laterally restrained in the perpendicular direction to the traffic in order fir the arching effect of concrete deck. In this paper, the minimum amount of FRP bar is to be suggested based on the structural strength, crack propagation, stress level and others in order to control cracks. As a result of laboratory tests, the structural strength of deck with 0.15 percentage of steel strap showed improved structural strength including ductility. The long-term serviceability of steel strap deck with FRP bar proved to satisfy the requirements and to be structurally stable while showing the amount of crack and residual vertical displacement within the allowable limits after two million cyclic loadings. The structural failure of RC bridge deck is generally caused from the punching shear rather than moment. Therefore, the ultimate load at failure could be estimated using the shear strength formula in the two-way slab based on ACI and AASHTO criteria. However the design criteria tend to underestimate the shear strength since they don't consider the arching effects and nonlinear fracture in bridge deck with lateral confinement. In this paper, an equation to estimate the punching shear strength of steel strap deck is to be developed considering the actual failure geometries and effect of lateral confinement by strap while the results are verified in accordance with laboratory tests.