• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.49 no.5
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• pp.278-286
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• 2023

Objectives: This review assessed the performance of implant-supported fixed hybrid prostheses in 21 patients who received a total of 137 implants between 2003 and 2010. The implants were evaluated for marginal bone resorption, complications, success rate, and survival rate based on their vertical angularity, type of bone graft, and measured implant stability. Materials and Methods: One-way ANOVA and chi-square tests were used to analyze the relationships among long-term evaluation factors and these variables. The mean initial bone resorption in the implant group with a vertical angle of more than 20° was 0.33 mm and mean final bone resorption was 0.76 mm. In contrast, the mean initial bone resorption in the implant group with a vertical angle of less than 10° was 1.19 mm and mean final bone resorption was 2.17 mm. Results: The results showed that mean bone resorption decreased with an increase in the vertical placement angle of the implants used in fixed hybrid prostheses, as well as in the group without additional bone grafts and those with high implant stability. The success rate of implants placed after bone grafting was found to be higher than those placed simultaneously. Conclusion: These results suggest that implant-supported fixed hybrid prostheses may be an effective treatment option for edentulous patients, and intentionally placing implants with high angularity may improve outcomes.

• Journal of the Ergonomics Society of Korea
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• v.19 no.2
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• pp.15-31
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• 2000

The aim was to evaluate the prevailing ergonomic and psychosocial conditions regarding low back injury in an automobile assembly system. This study consisted of two parts. In the first part of the study, analytic biomechanical model and NIOSH guidelines were applied to evaluate risk levels of low back injury for automobile assembly jobs. Total of 246 workers were analysed. There were 20 jobs having greater back compressive forces than 300kg at L5/S1. Also, there were 44 jobs over Action Limit with respect to 1981 NIOSH guidelines. This might in part be explained by the ergonomic conditions of the company analysed generally being good, with a relatively low duration of 'combined' extreme work posture. The relationship between psychosocial factors and low back injury was examined in the second part of the study. It has recently been recognized that overall reaction to working conditions was influenced by a range of factors, some of which were physical and some psychosocial. The psychosocial environment surrounding the work place may contribute to the perception of risk and eventual ill-health. A battery of questionnaires concerning the psychosocial stress based on PWI(Psychosocial Well-being Index) and musculoskeletal pain symptoms at low back was completed by 246 workers at the same plant. Results showed that 207 out 246 workers experienced the symptoms and 27 workers were diagnosed as patients. Two groups(low stressed, high stressed) based on PWI score had no significant relationships with both symptoms and results of diagnosis. However, sensitivities for symptoms and diagnosis by PWI were 91.3% and 92.6% respectively. Finally, relationships between physical work load and psychosocial stress were analysed. Specifically, some postural factors {vertical deviation angle of forearm, horizontal deviation angle of upperarm, vertical deviation angle of thigh, etc) were highly correlated with psychosocial stress. The results illustrated that PWI scores were associated with some physical workloads. However, psychosocial stress levels couldn't be well related with the pain symptom as well as the actual incidence of low back injury since pain or discomfort regarding low back injury were more complex than that of other musculoskeletal disorders.

• Korean Institute of Interior Design Journal
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• v.26 no.5
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• pp.143-151
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• 2017

This study aims to analyze the design of public libraries which act as anchors in culture-led urban regeneration. They have been built as city's symbols as well as catalysts to revitalize city centers and urban spaces since the 1990s. This study finds that the public libraries play roles in the urban development as cultural icons, multi-functional spaces, and public domain. This study examines the five examples of the libraries and finds their important design qualities as follow. First, public libraries are planned to symbolize local culture and history as cultural icons. The shapes of public libraries are expressed with sculptured cultural icons, while their facades are designed to signify cities' identities and images. Second, public libraries in culture-led urban regeneration have multi-functional spaces which provide diverse activities and experiences to visitors. The libraries often have galleries and theaters for cultural life, cafes and shops for daily uses, educational facilities, as well as public services, parking, and transport systems that connect to urban infrastructure. Third, the public libraries become the anchors of surrounding public spaces and cultural buildings. The libraries have the sequences of approach from entry plazas, transitional zones, and entrances to lobbies. Especially the transitional zones between the libraries and the cities that are covered with giant cantilevers expand the libraries' space and establish attractive urban spaces. Forth, the libraries employ nature and cityscapes in their design. The surfaces and openings of the libraries are adjusted to allow many attractive views to visitors. Fifth, the libraries have big lobby spaces which are the centers of the buildings as well as the public domain. The lobby spaces are designed as in-door spaces like out-doors with vertical and horizontal openness that allow the natural flows of light from ceilings, glass walls and vertical voids.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.4
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• pp.115-123
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• 2000

This study compared the degree of consolidation by hyperbolic, curve fitting , Asaoka's and methods using values measured with a theoretical curve in consideration of smear effect and well resistance. The degree of consolidation by the Hyperboilc method was underestimated than the degree of consolidation by Curve fitting. Asaoka's , and Monden's methods. The typical range of the coefficient of horizontal consolidation was Ch=(2-3)Cv in the case considering smear effect and well resistance, and Ch =(0.5-2.1) Cv in the case disregarding smear effect and well resistance. The degree of consolidation obtained by ground settlement monitoring was nearly the same value when the coefficient of smear zone permeability by back analysis was shown to be half that of in-situ and the diameter of the smear zone was shown to be double that of mandrel. By increasing the diameter reduction ratio of the drain, the time of consolidation was delayed. The effect of well resistance showed that the case of a small coefficient of permeability was much more than in the case of a large coefficient of permeability . It was recommended that when designing diameter reduction of a drain, well resistance should be considered.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2555-2559
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• 2003

In this study, we develop an automatic sorting system, which is mostly affected by frictional forces between a veneer and friction-generating device. So we will make a suitable dynamic model and mechanism to control friction force using a AC servo-motor. We suggest Stick friction and Column friction model, which is occurred between roller and veneer and within veneers as well. A kind of sensor can get the velocity of roller and movement of roller vertical direction. We assume that the several things to simplify the complicate and difficult nonlinear friction phenomenon. And to create an optimal normal force, which can generate a suitable friction force, we control the movement of sorting roller and supporter as well. We introduce several results about a friction character and suggest the value of calibration of sorting roller movement and supporters as well.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.93-97
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• 2002

This research introduces some preliminary results of bank filtering intake method adopted in Dalseo area, Nakdong River. This intake method has been planned to supply water resources of 41,000 ㎥/day to Goryeong-Gun and Seongju-Gun in 2016. It is believed that the bank filtering intake method can afford to supply 41,000 ㎥/day amount of water resources and that the raw water quality using the method has more advantages in water treatment than direct surface water intake. Even though the safety yield about individual vertical well is roughly estimated to about 2,000 ㎥/day, it is desirable to decrease the safety yield to about 1,000 ㎥/day in the consideration of long term and simultaneous well pumpings and other unknown factors. Ongoing study will give basic data and new techniques to solve the problems appearing in application of bank filtering method as well.

• Korean Journal of Materials Research
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• v.13 no.7
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• pp.415-419
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• 2003

Carbon nanotubes were formed on silicon substrate using microwave plasma-enhanced chemical vapor deposition method. The possibility of carbon nanotubes formation was related to the thickness of nickel catalyst. The growth behavior of carbon nanotubes under the identical thickness of nickel catalyst was strongly dependent on the magnitude of the applied bias voltage. High negative bias voltage (-400 V) gave the vertically well-aligned carbon nanotubes. The vertically well-aligned carbon nanotubes have the multi-walled structure with nickel catalyst at the end position of the nanotubes.

• Electrical & Electronic Materials
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• v.10 no.9
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• pp.922-929
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• 1997

As the size of semiconductor devices shrinks in the horizontal as well as vertical dimension it is difficult to estimate the transport-velocity of electron because they drift in non-equilibrium with a few scattering. In this paper HYbrid Monte Carlo simulator which employs the drift-diffusion model for hole-transport and Monte Carlo model for electron-transport in order to reduce the simulation time and increase the accuracy as well has been developed and applied to analyze the electron-transport in InAlAs/InGaAs HBT which is attractive for an ultra high speed active device in high speed optical fiber transmission systems in terms of the velocity and energy distribution as well as cutoff frequency.

• International Journal of High-Rise Buildings
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• v.1 no.2
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• pp.117-123
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• 2012

This paper discusses major strengths of tall buildings that distinguish them as sustainable solutions for the built environment. It sheds light on some of the key attributes of tall buildings as well as materials and technologies that could boost their performance environmentally, economically and technically as well as the natural habitats containing them. Tall buildings are portrait as major successful options for accommodating the ever increasing urban world population, with little negative impact on ecologies and environmental habitats worldwide. The role of tall buildings as 'vertical garden sub-cities' mitigating modern city problems of 'urban heat islands' and sprawling cities is explored. A few building examples as well as city developments are presented which represent the new generation of sustainable tall buildings that are setting trends for future projects incorporating innovations in materials and building systems and designs.

• Journal of the Korean Society of Groundwater Environment
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• v.7 no.2
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• pp.89-96
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• 2000

Slug tests are the most widely used field method for quantification of hydraulic conductivity of porous media. Well recovery is affected by well casing, borehole radii, screened length, hydraulic conductivity, and specific storage of porous media. In this study, a new slug tests model was developed through finite element approximation and the validity and usefulness of the model were tested in various ways. Water level fluctuation in a well under slug test and cons-equent groundwater flow in the surrounding porous medium were appropriately coupled through estimation of well-flux using an iteration technique. Numerical accuracy of the model was verified using the Cooper et al. (1967) solution. The model has advantages in simulations for monitored slug tests, partial penetration, and inclusion of storage factor. Volume coverage of slug tests is significantly affected by storage factor. Magnitude and speed of propagation of head changes from a well increases as storage factor becomes low. It will be beneficial to use type curves of monitored head transients in the surrounding porous formation for estimation of specific storage. As the vertical component of groundwater flow is enhanced, the influence of storage factor on well recovery decreases. For a radial-vertical flow around a partially penetrated well, deviations between hydraulic estimates by various methods and data selection of recovery curve are negligible on practical purposes, whereas the deviations are somewhat significant for a radial flow.