• Journal of Biosystems Engineering
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• v.35 no.4
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• pp.215-223
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• 2010

In order to develop an precision aerial pesticide application system to be attached to an unmanned helicopter which can be applied to small lots of land, this study analyzed the flowing and spraying characteristics of the spray droplets by the main rotor downwash by setting the application conditions at the flight altitude of 3 m, the diameter of main rotor of 3.1 m, the boom length of around 2.8 m, and the spraying rate of 8 L/ha. The results of this study are summarized below. Through analysis of the covering area ratio of the spray droplets by main rotor downwash by nozzle type, boom with tilt angle and height, it was found that the covering area ratio of the twin flat-fan nozzle of around 25% was more uniform than other types of nozzle, also boom with $10^{\circ}$ tilt angle and spraying height of 3 m was shown to be the appropriate conditions for aerial application of pesticides. It was found that the nozzle position to minimize the scattering loss of spray droplets due to vortex phenomenon at both ends of the main rotor was around 10 cm from the end of the main rotor. An application test for the aerial pesticide application system attached to the HUA-ACEI unmanned helicopter developed by the Rural Development Administration showed that the range of covering area ratio of the spray droplets was 10-25%, and the spraying width was approximately 7 m when over 10% of covering area ratio was considered for valid spraying.

• The Journal of the Korea Contents Association
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• v.16 no.9
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• pp.460-472
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• 2016

The purpose of this study is to examine the factors affecting perceptions of successful aging and preparations for the later life among the baby boom cohort. The subject of survey is the baby boomer(from 1955 to 1963) and it was done from May 1 to September 15 in 2016. 814 self-reported questionnaires were used for final analysis by SPSS WIN18. The major results of this study were as follows: First, there were differences in the perception of successful aging by education level, subjective awareness of economic status, subjective awareness of health condition, marriage status. Second, there were differences in the preparations for the later life by education level, job, subjective awareness of economic status, subjective awareness of health condition. Third, The higher perception of successful aging was deserved to significantly affect preparations for the later life.

• Journal of Digital Convergence
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• v.12 no.11
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• pp.585-595
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• 2014

The purpose of this study is to examine the Baby Boom Generation's participation intention for and needs on the elderly education. The survey research was conducted with the 261 participants who were born in 1955 through 1974 years. The results of this study are as follows : First, 67.4% of the respondents have not experienced life-long education because the respondents have no time to learn. Second, the positive agreement of the participation intention is 64.3% because the elderly people want to cope with the social changes themselves. Third, the respondents want to have the need for the elderly education by taking a class about health education with the method of practical training in a welfare organization. In conclusion, as showed the survey research, the elderly have highly participation intention about elderly education, so this study indicates that the high quality programs of elderly education should develop and provide.

• Journal of Digital Convergence
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• v.16 no.1
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• pp.93-101
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• 2018

This study aims to understand the retirement preparation of Korean baby boom generation. For this purpose, the mediation effect of the parameter of retirement preparation was confirmed to their social participation attitudes that influenced on successful aging. The research tried to present policy alternatives. The frequency analysis, description analysis, correlation analysis, hierarchical multiful-regression analysis for the collected data were conducted with SPSS 23 program. The findings are as follows; First, social participation attitudes affect successful aging. Second, social participation affects retirement preparation. Third, retirement preparation affects successful aging. Fourth, the relationship of social participation attitudes and successful aging are influenced mediation effect of retirement preparation. Finally, discussed the future research topics.

• Journal of the Korea Safety Management & Science
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• v.19 no.1
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• pp.15-25
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• 2017

The findings were summarized as follows. The safety check by manufacturer showed that 6 of 13 companies are over the average occurrence of defects. It was expected that there would be a difference between manufacturing technology capability and production system of each manufacturer. Consequently, manufacturers should institutionally improve and strengthen certification items for the upward standardization of safety certification before factory. Second, the safety check by year showed that the results of this study accord with those of previous studies on defect time. Consequently, manufacturers should classify the 3-year-old equipment for vehicle-mounted MEWP into a special check subject to do a nondestructive test according to proven results, and also reflect the test in a safety test system to do regular preventive activities of equipment defects. Third, the safety check by part showed that the boom and outrigger parts of vehicle-mounted MEWP have the most defects. Stress concentration resulted in defects as the boom part was most frequently operated in the structural parts for a real work. To prevent this, it is suitable to improve the hardness of boom materials. The outrigger part needs improvement in safety devices with materials. As an outrigger supports the overturning moment of equipment, it is most affected by its load based on the operating radius, resulting in fatigue crack.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.99-105
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• 2022

This paper studied the mechanical characteristics of boom structures by verifying the modeling method of representing unit cells of triaxial woven fabric (TWF) composites. The modeling of the representative unit cell obtained the ABD matrix by analysing the behaviour of tensile, shear, bending, and torsion using the periodic boundary conditions for the beam element. This study aimed to validate the ABD matrix by comparing the tensile analysis output from a finite element program with the experimental results from an MTS 810 machine. Additionally, the mechanical characteristics of a TWF composite boom structure were determined through bending analysis and experiments. The findings of this research are expected to be beneficial for developing structures using TWF composites.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.277-286
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• 2010

Derrick or caterpillar crane is generally used for the long-span/cable-stayed bridge construction by pre-cast segment lifting from over-land or water transportation. The heavy weight of them, however, could make defects on unstable under-construction structure and, furthermore a method of conventional segment transportation is also able to occur additional time and cost. In this study, in order to improve conventional construction method, the newly developed derrick crane is mainly considered. It could be not only eccentrically loadable on constructing girder but having rotatable boom for segment transportation from back-side. A series of construction stage using developed derrick crane is defined and also its numerical analysis is conducted. To reflect load characteristics of developed derrick crane on construction stage analysis, on/out of service load is separately calculated by considering vertical/lateral rotation range of boom and it is loaded on 4 fixed positions of crane. The derrick crane on this study could be time and cost saving solution for cable-stayed bridge construction and also make contributions to construction load reduction in its process.

• Journal of Space Technology and Applications
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• v.3 no.3
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• pp.229-238
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• 2023

One of the important ways to improve the performance of magnetometers in satellite exploration is to reduce magnetic noise from satellites. One of the methods to decrease magnetic noise is by extending the satellite boom. However, this approach is often not preferred due to its high cost and operational considerations. Therefore, in many cases, removing interference from the satellite platform in the measured dataset is widely utilized after data acquisition. In this study, we would like to introduce an algorithm for removing magnetic noise observed from magnetometers installed on two solar panels and one main body without a boom.

• Journal of the Korean Society for information Management
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• v.35 no.3
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• pp.287-309
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• 2018

As coming Senior-Shift age, senior users are regarded as one of the importance user groups in the library. This study is to find the usage patterns and needs of libraries and digital libraries by 152 seniors and to compare with young-old age (baby boom generation) and elderly age. As a result, total seniors visited regularly and preferred political & social, religion & philosophy, and history & geography. While the baby boom generation are using the economy & finance, art & culture compared to the older. And the baby boom generation visit for self-development and the older visit for leisure purposes. Secondly, If the search fails, the baby boomers control the results themselves, while the older is more turn to the librarians. It can be described as the need for a librarian exclusively responsible for the senior. Thirdly, senior have difficulties in access and use of search aided tools or functions. Therefore, this study suggested that it is necessary to build an intuitive interface using the help and menu descriptions for senior who have poor access to convenience and define functions.

• Journal of Drive and Control
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• v.13 no.2
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• pp.10-18
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• 2016

A front-end loader (FEL) mounted on an agricultural tractor is one of the most commonly used implements to mechanize routine agricultural tasks. When the FEL is used with a loaded bucket, careful operation is required to maintain safety and avoid spillage when the tractor passes a bump because a change in the gravity center of the tractor due to varied loadings can affect the stability of the tractor. Use of a boom suspension system consisting of accumulators and orifice dampers can be instrumental in reducing pitching vibrations while increasing the handling performance of the FEL-mounted tractor. The objective of this research was to reduce bump shocks by adding an orifice and a flow control valve to the original hydraulic circuit composed solely of accumulators. A simulation study was performed using the SimulationX program to investigate the effects of an accumulator and an orifice-throttle damper on bump shocks. Results showed that the peak pressure on a boom cylinder and the vertical acceleration of a bucket were significantly affected by use of both an accumulator and an orifice damper. In a field test conducted with a 75-kW tractor, the peak pressure of the boom cylinder, and the root mean square (RMS) vertical acceleration of the bucket and seat were reduced by on average, 23.0, 42.2, and 44.9% respectively, as compared to those measured with the original accumulator system, showing that an improved design for the accumulator hydraulic circuit can reduce bump shocks. Further studies are needed to design a tractor suspension system that includes the effects of cabin suspension and tires as well as dynamic analysis.