• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.6
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• pp.707-712
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• 2012

Very high cycle fatigue (VHCF) behavior of aerospace components has emerged much attention due to their long service life. In this study, a piezoelectric ultrasonic fatigue testing (UFT) system has been developed by Mbrosiatec Co., Ltd. to study the high cycle fatigue (HCF) strength of Ti-6Al-4V alloy. Hourglass-shaped specimens have been investigated in the range from $10^6$ to $10^9$ cycles at room temperature under completely reversed R = -1 loading conditions,. Scanning electron microscopy (SEM) analysis revealed that failures occurred in the entire range up to the gigacycle regime, and the fractures have beenfound to be initiated from the surface, unlike in steels. However, it was found from the SEM microgprahs that microcracks transformed into intergranular fractures. Thus, it can be concluded from according to the results that this test method can be applicable to commercialized automotive and railroad parts that require high cycle fatigue strength.

• Research in Community and Public Health Nursing
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• v.13 no.2
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• pp.260-271
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• 2002

Objectives: The purpose of this study was to identify basic health needs of adult clients to develop a community nursing center model in Seoul. Methods: Data were collected using a questionnaire survey from 894 adults registered at a public health center who were health management members, and visiting 4 community nursing centers, University of Wisconsin, Milwaukee during the period from July 1999 to January 2000. The data were analyzed using frequency, percentile, t-test, and ANOVA. Results: 1) The University of Wisconsin- Milwaukee School of Nursing has a long tradition of developing 4 community nursing centers with innovative health care programs. CNCs integrate the ability to implement and test effective intervention strategies with education, research, and practices of nursing students and faculty. They were designed to enhance the health status and quality of life for urban communities through the development of productive, outcome focused, collaborative partnerships among UWM-Nursing faculties and staff, other health and human service providers, consumers, and policy makers. It links the financial resources between UWM and 9 voluntary agencies and 12 public funding organizations including federal. state, and local governments. 2) Of the total health management members, 37.4% were reported to have at least one type of chronic disease such as hypertension, diabetes, and arthritis. Ten percent of them reported having obesity, and 44.2% reported lack of exercise. The health status of the subjects was within normal range in laboratory tests. However, female subjects showed more significant differences in obesity and cholesterol levels than male subjects. The subjects, who were in their 50s, showed more significant differences in obesity, SGOT, SGPT, and cholesterol levels than the subjects in other age groups. Conclusion: A community nursing center needs to be developed, that has a link between the nursing college and the public health center, with partnerships and a multidisciplinary approach. Based on the study results, exercise programs for middle aged adults are considered necessary. In particular, specific exercise programs for pre-menopausal women needs to be implemented in the future to prevent them from developing osteoporosis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3973-3982
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• 2012

The purpose of this study was to identify cognitive impairment and it's related factors of the elderly in long term care facilities. The participants of this study were 229 residents of five nursing homes. Data were analyzed using two sample t-test, ${\chi}^2$-test, and logistic regression. The results revealed eight factors related to cognitive impairment: gender(OR=2.41, p=.035), age(75-84: OR=3.26, p=.002, Over 85: OR=4.46, p<.001), living with family before admission(OR=2.17, p=.015), hearing(OR=8.88, p=.004), family history of dementia(OR=4.39, p=.009), ADL(OR=0.82, p<.001), hypertension(OR=4.07, p<.001), and diabetes(OR=3.42, p=.001). Based on the findings of this study, continuous nursing intervention focused on adjustable factors would be helpful in order to improve nursing home elderly people's quality of life.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.947-952
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• 2010

Components such as pressure vessel, hydraulic hose assembly, accumulator, hydraulic cylinder, hydraulic valve, pipe, etc., are tested under the impulse-pressure conditions prescribed in ISO and SAE standards. The impulse pressure test machine needs to have a high pressure, a precise control system and a long life. It should satisfy the requirements for fabrication of the impulse tester to generate ultra high pressure in the hydraulic system. In the impulse tester, a servo-valve control system is adopted; although the control application is convenient, it is expensive owing to the cost of developing the system. The type of the control system determines the pressure wave, which affects the components that are tested. In this study, the manufacturing process and the intensifier system design related to the flow, pressure, and the increasing rate of pressure are investigated. The results indicate the ultra high pressure waves in the system.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.285-289
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• 2006

Recently the target area for the installation of structures have been changed from shallow water into deep one by reservation and use of the wider coastal region, and development of deep water. Additionally, great emphasis in the improved human life quality has been placed on the necessities for the preservation of the agreeable natural and coastal environments and development waterfront, recreation, and resort in the sea. However, the existing gravity-type breakwater did not appropriately cope with the recent changes of circumstances, but required the enormous construction coat for coping with them. Until now, floating breakwuater, which was adequate for the environment and construction cost, has been actively studied in the other countries including Japan. This floating breakwater has been already constructed in many places and satisfactory in poor subsoil and deep water in Japan. Also it showed the same function as a gravity-type breakwater. But floating breakwater was not control long period waves by reason of constructive characteristic. The aim of this study is to discuss field application of Floating Breakwater with Compound Plate Type(FBCPT) in coastal region by using numerical analyses and hydraulic model test.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.261-264
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• 1997

Joints and terminations for 345kV Oil Filled $1C{\times}2000mm^2$ cable have been developed and tested including BPT (Bellows Pressure Tank) on the bases of various ultra-high voltage technologies. Electrical design was performed by using Finite Element Method. The type test certified by KEPCO (Korea Electric Power Corporation) has been performed as the final stage of development. In order to confirm the reliability of long-term life for 30 years, load cycle test was conducted for 30 days with good result. As the result, the techniques we obtained from this development are applicable to higher voltage level systems (i.e. 765 kV).

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.4
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• pp.323-333
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• 2005

Recently the fire is happening at the tunnel and underground - structure internationally. We are socially the economy the actual circumstances which serious loss is happening due to an fire occurrence when fire happened which is closed like tunnel and underground - structure, the collapse from the burglar degradation of strength of tunnel concrete lining and human life damage happen. It causes big problem while the long time disconnects a traffic network. While the fire happened in this research at the tunnel, the paper construct a basis data to deduce the specification regulation about stability of tunnel concrete lining. In this paper, the experiment was carried out for the prevention of explosive spalling of tunnel to use a reinforced Polypropylene concrete which mixes a Polypropylene which are known for the thing by being efficient at a protect of explosive spalling of the concrete. According to the firproof test result of reinforced Polypropylene admixture mortar, Polypropylene admixture of prevention of explosive spalling analyzed 0.2%-0.25%.

• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.334-341
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• 2008

Ballast track needs maintenance works because it is supported by the compressible trackbed and subgrade layers. Maintenance works are essential to secure riding comfort and extend the life cycle of it. The necessities of maintenance works are determined from track irregularities measured by EM120. Track irregularities is the results of the track deformation. Therefore, it is natural to evaluate the cause of it. This paper focuses on the points the track irregularities come from the trackbed and the subgrade. Nondestructive techniques, such as Ground Penetrating Radar (GPR) and Portable Falling Weight Deflectometer (PFWD) are applied to evaluate the trackbed conditions, ballast layer thickness and vertical track stiffness, in the test section 500m long of Gyungbu line. The trackbed investigation results are compared with the track irregularities measured by EM120 and maintenance works. Conclusively, it was found that some maintenance works were unnecessary on the test section.

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.1-8
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• 2015

When the line and switchgear of the substation system are disconnected, ferro-resonance can occur. This happens even if the capacitive reactance and inductive reactance are not equal, which are not common resonance conditions. Resonance conditions vary depending on the busbar configuration environment. Although the damping resistance method applying the existing saturable reactor to cope with ferro-resonance has been successfully applied on site, there can be loss of normal function during long-term operation. The reason is because the rise in the operating frequency of saturable reactors means the saturation number is increased. Therefore, it can no longer function as saturable reactor since the resistor having inadequate capacity is burned out. To address this problem, in this paper, an EMTP-based simulation test was performed by designing and applying a dual reactor method, which adds an extended divergence reactor to the 1st side of the VT. The test result confirms that when the divergence reactor is inserted, the voltage and current values obtained at the 1st side and 2nd side of the VT as well as current values of divergence reactor part were stabilized from the transient phenomena and return to normal values. When compared with existing measures, although this method is similar in adding having a reactor added to a system regarding ferro-resonance, it has the advantage of being able to prevent ferro-resonance in advance since the reactor is added before the system is saturated. In addition, because it does not use damping resistance, it can extend the equipment life and stabilize its operation. Therefore, there are a lot of differences in terms of its operating characteristics and achivement of goal between the conventional method and new divergence reactor method.

• Journal of Biomedical Engineering Research
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• v.35 no.5
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• pp.169-176
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• 2014

As body postures on bed affects various sleep related diseases, it is considered as important information when monitoring sleeping in daily life. Though there have already been a few approaches to monitor body postures on bed conventionally, the development for simple and unconstrained methods is still needed to realize the long-term daily monitoring. Focusing on the fact that ballistocardiogram changes depending on the body postures on bed, we developed a novel method to estimate body posturesusing extremely simple, film-type ballistocardiogram sensor which is based on polyvinylidene fluoride(PVDF) film. With 10 subjects, we performed two experiments. One was for an estimation test to show that body postures on bed can be estimated by ballistocardiogram, and the other was for a reproducibility test to present the feasibility of ballistocardiogram based body postures monitoring. To estimate body postures on bed, we made an individual template set of body postures by designating one ballistocardiogram (BCG) sample as a template in each postures. Then, we calculated Pearson's correlation coefficients between a sample and each templates and estimated the body posture of the sample by choosing a posture which corresponds to the most significant correlation coefficients. As a result, we estimated body postures on bed with 99.2% accuracy in average and found that the estimation using ballistocardiogram is reproducible.