• Proceedings of the KSME Conference
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• 2003.04a
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• pp.255-260
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• 2003

Most of the fatigue test were achieved in fully reversed condition that mean stress is zero. But, generally, mean stress can not be zero. This research was achieved the bending fatigue test that changes mean stress to spring steel and was studied relation with the mean stress and the fatigue life. The method to search effect about mean stress was extended S-N graph in two cases. One method was extended S-N graph using modified Miner's rule with considering damage. Another was extended using tendency of S-N graph. The exponential value(${\alpha}$) of mean stress-alternating stress equation is converged between the Goodman's and the Gerber's value even if fatigue life increases.

• Journal of the Korean Wood Science and Technology
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• v.24 no.3
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• pp.65-71
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• 1996

In the design of wood structures, the consideration of the dynamic load effect has been increased. Generally, damping ratio is presented as the method of considering dynamic load effect. So, the relationship between joint type and damping ratio was investigated. It has been known that the joint extremely damp the dynamic load in wood structures. Static test was performed to determine the effects of nail size and friction area on joint strength and stiffness. Joint strength and stiffness were increased with nail size. However, the static properties of joint was not affected by friction area. Cyclic test was performed to determine the effects of nail size, friction area and load magnitude on damping ratio, Damping ratio was affected by all factors. Increasing the width of the bottom plate was suggested as the most adequate method to increase the damping ratio without the reduction of the static properties of the structures.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1121-1124
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• 2004

Aging test to estimate life property of polymer insulator is executed through several international standard such as IEC 61109 and CEA tracking wheel test, but is not getting clear conclusion yet. There are two methods in the diagnosis method of polymer insulator such as off-line and on-line. The diagnosis methods in off-line are external condition analysis by the eye, contaminant analysis on surface, surface analysis, pollution withstand voltage test, power frequency flashover voltage test, lightning impulse flashover test, tensile fracture load test and flexural load test. The diagnosis methods in off-line most are the method for virgin and last aged sample. However, the diagnosis method in on-line is method that can be evaluate sample state as progressing continuously aging test in beginning, The diagnosis method in on-line is arranged as following: leakage current measurement, electric field, surface state investigation, thermal image, emitting light measurement and then so. In this paper, the tracking performance of polymer insulator with salt solution which is added surface active agent. The diagnosis of insulator sample has been analyzed by leakage current and visual examination.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.6
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• pp.100-106
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• 2012

Recently, the demand to acquire and improve durability performance has steadily risen in rubber components design. In design process of a rubber component, an analytical prediction is the most effective way to improve fatigue life. Existing methods of analytical estimation have mainly used an equation for fatigue life obtained from fatigue test data. However, such formula is rarely used due to costs and time required for fatigue testing, as well as randomness of rubber materials. In this paper, we describe fatigue life estimation of rubber component using only the results from a relatively simple tearing test. We estimated fatigue life of the Janggu type fatigue specimen and the automotive motor mount, and evaluated reliability of the proposed method by comparing the estimated values with actual test results.

• Journal of Korean Academy of Nursing
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• v.36 no.3
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• pp.484-492
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• 2006

Purpose: The purpose of this study was to investigate the effects of a rehabilitation nursing program(RNP) for persons with disabilities. Method: a quasi-experimental pretest and post test study was used to examine the changes of patient's muscle strength, flexibility, self efficacy and health related quality of life at the completion of an 8-week education and physical exercise with a Thera-Band and Exercise Ball course. The subjects consisted of 40 adults who were disabled. Twenty-two experimental and 18 control subjects completed pre and post-test measures. Outcome variables were flexibility, hand grip, elbow flexor and extensor, knee flexor and extensor, self efficacy and quality of life. Independent t-test and ANCOVA were used to examine group differences by using SPSS 12.0 Result: Mean comparisons of the change scores revealed that the experimental group increased significantly in knee extremity flexor(p=0.035), extensor(p=0.039), flexibility(p=0.008), self efficacy(p=0.000), and quality of life(p=0.000). No significant group differences were found in each patient's hand grip, elbow flexor and extensor. Conclusion: RNP can improve lower extremity flexibility, muscle strength, self efficacy and health related quality of life in people with disabilities. The intervention to tailor exercise and education to the unique needs of the disability was suggested for further study.

• Perspectives in Nursing Science
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• v.16 no.1
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• pp.25-34
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• 2019

Purpose: Alcohol use in South Korean women, particularly college students, is increasing. Women are more vulnerable than men to alcohol use, which puts them at greater risk of physical and psychosocial problems. Some studies have reported that on failing to find meaning in life, many South Korean college students experience depression, subsequently using alcohol as a coping mechanism. This study aimed to develop a logotherapeutic program and identify its effects on meaning in life, depression, and problem drinking among female college students. Methods: This study was a quasi-experimental trial. The participants were female college students who scored over 8 in the Alcohol Use Disorders Identification Test (AUDIT). Twenty-four students were assigned to the experimental group and twenty-three to the control group. Three scales were used in this study: the Purpose in Life test, Beck Depression Inventory, and AUDIT. The data were analyzed using the Mann-Whitney test in SPSS/WIN 12.0. Results: After the conclusion of the logotherapeutic program, the level of meaning in life and depression were more greatly improved in the experimental group than the control group. Conclusion: The logotherapeutic program is an effective method to help female college students find meaning in life and reduce depression in this population.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.5
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• pp.52-57
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• 2007

Corrugated fiberboard is a representative packaging material because of high compressive strength and stiffness in spite of light weight. The flutes of corrugated fiberboard are various depending on the height and the number per unit length of flute. The corrugated fiberboard with microflute like E, F or G with low height less than 1.5 mm has developed. Because it has some advantages including higher stiffness and lower requirement of fiber than carton board, it has a possibility to replace folding box board. Its consumption has been increased with the various applications like graphic packaging. As microflute has the different geometry from other conventional flutes, it can show the different behavior in testing and it may require a new testing method. In this study, we evaluated the edgewise compressive strength of the corrugated fiberboard with microflute according to ISO and other standard test methods. And the effect of specimen shape and platen compression rate was examined. From this study, we found that ISO methods was suitable and reasonable methods for corrugated fiberboard with microflute.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.5
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• pp.233-238
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• 2021

The mechanical, anti-tarnishing, and corrosion characteristics of Yuggi (Cu-22wt%Sn) alloy are greatly affected by fraction of constituent phases according to heat treatment method. The Yuggi heat-treated at 750℃ has a β1' phase of 98% or more, which is a high-temperature disordered beta phase, on the other hand, cast Yuggi that Sn is solid-solutioned into Cu consists with α-phase over 60v/o. This difference of constituent phases of Yuggi may cause a difference in dissolution of Cu under antimicrobial test condition. Nonetheless, few studies have been conducted on the effect of fraction of constituent phases and constituent phases in antimicrobial activity. In addition, few studies have also been conducted on the suitable method measuring the antimicrobial activity of Yuggi. Hence, the purpose of this study is to provide an optimum measurement method of antimicrobial activity, and to evaluate quantitatively the effect of constituent phases on antimicrobial activity.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.217-222
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• 2001

For the life evaluating of notched members, it is the best way that performing the real fatigue test of structure containing notch. But this method required generally much times and costs to evaluate fatigue life. So, generally we use the modified S-N curve or several methods to predict fatigue life. In this study, crack initiation life was evaluated by fatigue testing the SAE keyhole specimen and smooth specimen made of Al 7075-T6 alloys using the constant load then obtained S-N curve of smooth specimen and P-N curve of SAE keyhole specimen. And, fatigue lives of keyhole specimen are predicted using some life prediction methods (Nominal range I method, Nominal range II method, FEM analysis) for investigating experimented results, and that were compared with experimental data. Predicted fatigue lives by FEM analysis were corresponded with experimental data between 1/3times and 3times on the whole, and predicted fatigue lives using modified S-N curve (Nominal range I method, Nominal range II method) were nonconservative compared with that of FEM analysis.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.1123-1134
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• 2020

The goal of this study was to develop an accelerated life test for an implement working pump for an agricultural tractor. The field experiments were conducted to measure the load of an implement working pump during major agricultural operations such as plow tillage, rotary tillage, baler operations, and wrapping operations. The measurement system for an implement working pump load was constructed using a pressure sensor, the engine rotational speed, and the hitch pump displacement. The measured implement working pump load was calculated as an equivalent load for each agricultural operation using the Palmgren-Miner rule, which is a cumulative damage method. The equivalent load was calculated using the total load data and peak load data when the total data included the operation of an implement working. The annual usage time of the agricultural tractor was applied to develop two integrated equivalent loads. The acceleration factor was calculated to develop an accelerated life test and was calculated from the two integrated equivalent loads, the maximum pressure, and the flow rate conditions of the hitch pump. In Korea, the warranty life of a tractor is 2,736 hours, and the time required for the test to guarantee the operational life of tractors was calculated as 7,561 hours. The acceleration factors were calculated as 453.6 and 38.3, respectively, from the total load data and peak load data. The fatigue test time can be shortened by 16.7 and 197.4 hours according to the result of the acceleration factors.