• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.90.2-90.2
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• 2012

Geosynchronous electron flux dropouts are most likely due to fast drift loss of the particles to the magnetopause (or equivalently, the "magnetopause shadowing effect"). A possible effect related to the drift loss is the radial diffusion of PSD due to gradient of PSD set by the drift loss effect at an outer L region. This possibly implies that the drift loss can affect the flux levels even inside the trapping boundary. We recently investigated the details of such diffusion process by solving the diffusion equation with a set of initial and boundary conditions set by the drift loss. Motivated by the simulation work, we have examined observationally the energy spectrum and pitch angle distribution near trapping boundary during the geosynchronous flux dropouts. For this work, we have first identified a list of geosynchronous flux dropout events for 2007-2010 from GOES satellite electron measurements and solar wind pressures observed by ACE satellite. We have then used the electron data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft measurements to investigate the particle fluxes. The five THEMIS spacecraft sufficiently cover the inner magnetospheric regions near the equatorial plane and thus provide us with data of much higher spatial resolution. In this paper, we report the results of our investigations on the energy spectrum and pitch angle distribution near trapping boundary during the geosynchronous flux dropout events and discuss implications on the effects of the drift loss on the flux levels at inner L regions.

• Journal of the Korean Geographical Society
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• v.44 no.4
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• pp.544-556
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• 2009

The purpose of this study is to examine the determinant factors of satisfaction and to investigate the difference from clusters in the category of overall state of satisfaction, the thought of revisiting, and the intention of recommendation with the case of Wando Changpogo Festival. Changpogo Festival has been held since 1996 with the theme of 'Changpogo', gained great acknowledgment from television drama, 'Haeshin', and this year of 2009 is its fourteenth. The study analyzed questionnaire which is made up of items on satisfaction factors of 18 local festival visitors. Results from factor analysis are 1) the contents and the souvenir of the festival, 2) work for publicity, 3) tour for near place and convenient facilities. Likewise, results from cluster analysis are 1) a cluster of the contents and the souvenir of the festival, 2) a cluster of tour for near place and convenient facilities, 3) a cluster of work for publicity. In conclusion, there are similar degrees in difference between clusters, but especially the 'tour for near place and convenient facilities' factor has higher score than the others. Therefore, this factor should be cared with great importance.

• Korean Journal of Construction Engineering and Management
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• v.15 no.2
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• pp.122-131
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• 2014

As plant market grows up, client demands to increase quality, technology and to reduce construction period. Due to the vast scale of the construction site and complexity of process, plant project can have some problems of communication among the project participants, the duplication of work, errors and rework. As a result those cause more costs, delay the construction schedule and reduce productivity and quality. Therefore, real-time communication between participants and real-time sharing of information such as material, equipment and construction are required in plant project site. This research aims to propose process and develop system using NFC(Near Field Communication) technology and augmented reality technology with mobile device for plant construction site. Administrators and operators are able to work efficiently using proposed process and system which create an environment designed to share and deliver information such as material, construction information.

• Korean Institute of Interior Design Journal
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• v.21 no.1
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• pp.170-176
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• 2012

Korean living culture raised the users' needs for sub-kitchen. In the traditional Korean house, there was large space related to kitchen area for preparing food and stock big and bulky housing stuffs. As apartment housing became dominant as Korean dwelling, sub-kitchen has been planed in the balcony that is not included in the sales area. In this study, the case of the apartment housing in Esiapolis, Daegu was analyzed. To plan the user-oriented sub-kitchen, the consumer research was carried out. Consumers needed a pantry, more storage near the kitchen, and wanted to place washing machine and washing stand in a sub-kitchen. Sub-kitchens were planed to meet those consumers' needs. Through this case study and former studies analysis, sub-kitchen's function unit was derived: wash, storage, auxiliary work. By combining each function unit, sub-kitchen was classified into 3 types, wash & auxiliary work, wash & storage, and wash & storage & auxiliary work. For each sub-kitchen type, components of function units, available layouts, and minimum size were recommended.

• Journal of the Korean Home Economics Association
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• v.38 no.1
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• pp.171-183
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• 2000

The purposes of this study were to identify the needs for the employer-supported day care service and to analyze the factors related to the needs for the day care service of the married employees. KLFI(1995)'s National data were used and three Logistic models and one Catmod model were employed to analyse the effects of the independent variables on the needs for the day care service. The results of this study were as follows: First, half of employed workers needed the employer-supported child care service. Second, they preferred the day care center near their residential area than in their work site. Third, according to their age, type of occupation, and their difficulties for the childcare and household work, employed men and women needs on site day care differently. Finally, their needs for the expenditure of duty care service differed by their age, sex, and occupation, and their levels of difficulties for the childcare and household work. These findings suggest that duty care service for the employed man and woman are supported diversely according to their needs and preferences.

• Journal of the Korea Safety Management & Science
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• v.5 no.1
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• pp.69-82
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• 2003

The sequence which minimizes overall utility work in car assembly lines reduces the cycle time, the number of utility workers, and the risk of conveyor stopping. This study suggests mathematical formulation of the sequencing problem to minimize overall utility work, and present a genetic algorithm which can provide a near optimal solution in real time. To apply a genetic algorithm to the sequencing problem in car assembly lines, the representation, selection methods, and genetic parameters are studied. Experiments are carried out to compare selection methods such as roullette wheel selection, tournament selection and ranking selection. Experimental results show that ranking selection method outperforms the others in solution quality, whereas tournament selection provides the best performance in computation time.

• Journal of the Korean Society of Safety
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• v.11 no.3
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• pp.168-176
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• 1996

Statistical analysis of occupational accidents plays an important role in establishing measures against accidents and for evaluating safety performance in work places. This research work, numerous numbers of research work have been conducted, which attemped to verify the existence of !he concept of "accident proneness" Also researches have been developed in the fields of systems safety analysis and risk analysis to analyze the characteristics of occupational accidents. This paper presents a brief historical review of these research activities with particular emphasis on the statistical analysis of occupational accidents. Based on this review, further development needs in relation to the statistical research on the occupational accidents in the near future are discussed.discussed.

• Advances in aircraft and spacecraft science
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• v.9 no.4
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• pp.319-333
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• 2022

This work presents a numerical investigation of the aerodynamics and aero acoustics of the HVAB rotor in hover conditions. Two fully turbulent models are employed, the one-equation Spalart-Allmaras model and the two-equation k-ω SST model. Transition effects are investigated as well using the Langtry-Menter γ-Re θt transition transport model. The noise generation and propagation are being investigated using the Ffows-Williams Hawking model for far-field noise and the broadband model for near-field noise. Comparisons with other numerical solvers and with the PSP rotor test data are presented. The results are presented in terms of thrust and power coefficients, the figure of merit, surface pressure distribution, and Sound pressure level. Velocity, pressure, and vortex structures generated by the rotor are also shown in this work. In addition, this work investigates the contribution of different blade regions to the overall noise levels and emphasizes the importance of considering specific areas for future improvements.

• Journal of Biomedical Engineering Research
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• v.44 no.6
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• pp.450-464
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• 2023

Pulse oximetry, a non-invasive technique for evaluating blood oxygen saturation, conventionally depends on isolated measurements, rendering it vulnerable to factors like illumination profile, spatial blood flow fluctuations, and skin pigmentation. Previous efforts to address these issues through imaging systems often employed red and near-infrared illuminations with distinct profiles, leading to inconsistent ratios of transmitted light and the potential for errors in calculating spatial oxygen saturation distributions. While an integrating sphere was recently utilized as an illumination source to achieve uniform red and near-infrared illumination profiles on the sample surface, its bulkiness presented practical challenges. In this work, we have enhanced the pulse oximetry imaging system by transitioning illumination from an integrating sphere to a multi-wavelength LED configuration. This adjustment ensures simultaneous emission of red and near-infrared light from the same position, creating a homogeneous illumination profile on the sample surface. This approach guarantees consistent patterns of red and near-infrared illuminations that are spatially uniform. The sustained ratio between transmitted red and near-infrared light across space enables precise calculation of the spatial distribution of oxygen saturation, making our pulse oximetry imaging system more compact and portable without compromising accuracy. Our work significantly contributes to obtaining spatial information on blood oxygen saturation, providing valuable insights into tissue oxygenation in peripheral regions.

• Journal of Ocean Engineering and Technology
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• v.29 no.1
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• pp.45-55
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• 2015

Because of the high stress concentration near the toe of a welded joint, the calculation of local stress using the finite element method which is relevant to the fatigue strength of the weld toe crack, is a challenging task. This is mainly caused by the sensitivity of finite element analysis, which usually occurs near the area of a dramatically changing stress field. This paper presents a novel numerical method through which a less mesh-sensitive local stress calculation can be achieved based on the 3D solid finite element, strictly sticking to the original definition of hot spot stress. In order to achieve the goal, a traction stress, defined at 0.5t and 1.5t away from the weld toe, was calculated using either a force-equivalent or work-equivalent approach, both of which are based on the internal nodal forces on the imaginary cut planes. In the force-equivalent approach, the traction stress on the imaginary cut plane was calculated using the simple force and moment equilibrium, whereas the equivalence of the work done by both the nodal forces and linearized traction stress was employed in the work-equivalent approach. In order to confirm the validity of the proposed method, five typical welded joints widely used in ships and offshore structures were analyzed using five different solid element types and four different mesh sizes. Finally, the performance of the proposed method was compared with that of the traditionally used surface stress extrapolation method. It turned out that the sensitivity of the hot spot stress for the analyzed typical welded joints obtained from the proposed method outperformed the traditional extrapolation method by far.