• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3658-3665
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• 2010

As the population of elderly people and disabled people are increased, various demands for human welfare using robot system are raised. Especially autonomous rehabilitation system using robot could reduce the human effort while maintaining the its intrinsic efficacy. This study deals with mobile gait rehabilitation system which combined with BWS (Body Weight Support) for training of elderly and handicapped people who suffer the muscle force weakness of lower extremity. BWS which is designed by kinematic analysis of body lifting characteristics and walking guide system are integrated with main control system and wheeled platform. This mobile platform is operated by UCS (User Command System) and autonomous trajectory planning algorithm. Finally, through the EMG (Electromyography) signal measuring and its analysis for subject, performance and feasibility of developed system is verified.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.167-178
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• 2000

An experimental study on step up filling method is carried out to reinforce the Yano method which is widely used to estimate volume ratio and self-weight consolidation settlement in reclamation area. This method considers actual reclamation construction in which dredged clay is continuously filled and rising of deposit height is presented as a result of volume decrease by height rising and self-weight consolidation. It measured the relationship between filling velocity and deposit rising velocity; calculated the total filling height which is needed to achieve the planned final deposit height, and its solid height and the time which is taken to finish the planned final deposit height; and on the basis of these calculated parameters, predicted the self-weight consolidation and volume change ratio in reclamation construction. Yano method is also used to predict the same conditions. 29.8% in self-weight consolidation, 31.1% in volume ratio, 40% in void ratio and water content is underestimated in Yano method compared to step up filling method.

• Journal of Korean Society of Steel Construction
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• v.19 no.3
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• pp.313-321
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• 2007

The study discussed in this paper presents a method of estimating sources of geometric errors in suspension bridges in use, based on geometric survey data. A geometric error is defined as the difference between the survey data and the design geometry of a main cable. It is assumed that the geometric error in a suspension bridge is caused by the variations in the weight of the stiffening girder and the deformation of the anchorage foundations due to the creep of soil. The variations in the girder weight and the deformation of the foundation were estimated by constructing a matrix of factors that affect suspension bridges due to the variations. To check the validity of the proposed method, it was applied to the Kwang-An Bridge, and the sources of geometric errors in the bridge were estimated using the survey data.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.32.5-33
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• 2009

카네기 천문대에서 주도하여 개발 중인 구경 25.4m GMT 망원경 사업에 한국도 공식적으로 참여하였다. 현재 한국천문연구원은 GMT(Giant Magellan Telescope)부경부를 국내에서 개발하고자 이와 관련된 연구를 진행하고 있다. GMT 부경은 직경 1.06m 오목거울 7장이 모여 전체 직경 3.2m인 타원면을 형성하고 초점비는 F/0.7이다. GMT 부경개발 선행 연구과제로 카네기 천문대에서 개발되어 현재 운용중인 구경 6.5m 마젤란 망원경의 부경을 선택하였는데, 이는 마젤란 부경의 형상과 직경, 부경시스템 운영방식이 GMT 와 유사하기 때문이다. 천체관측 망원경에서 거울면의 변형에 가장 큰 영향을 미치는 인자는 거울의 자중이다. 거울의 직경이 커지면 자중이 증가하게 되어 거울면의 처짐이 커지게 된다. 이를 극복하고자 다양한 거울 support들이 개발되었다. 그중에서 counterweight lever 시스템 같은 부양(float) 시스템은 자중의 영향을 보상해 줌으로써 그것에 의한 거울의 변형을 최소화하는 역할을 하는데, GMT 부경 개발에 근간이 되는 마젤란 부경 또한 부양 시스템을 도입하였다. 마젤란 부경의 부양시스템은 counterweight lever 시스템과 유사한 진공 시스템을 도입하였다. 마젤란 부경의 support는 axial 방향으로 거울을 지지하는 axial support와 lateral 방향으로 거울을 지지하는 lateral support가 있는데, 이중에서 axial support가 진공시스템으로 구성된다. Lateral 방향의 지지는 경량화된 거울의 hole 안에 3개의 판스프링을 삽입하여 단지 거울과 판스링의 강성에 의해서만 이루어진다. 이 논문에서는 망원경이 작동을 할때 즉, 천정각(zenith angle)이 변할 때 axial support와 lateral support의 조합(combination)에 의해 지지되는 마젤란 부경의 표면 정밀도 RMS 값을 비교하였다.

• The Journal of Korean Association of Computer Education
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• v.21 no.3
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• pp.35-50
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• 2018

Online dashboard is designed to support learners' self-regulation of their learning process and activities to promote learner-centered learning. Given the dashboard usually provides information within a limited space, it is important to define which information should be presented in order to meet the various needs of online learners. We analyzed relevant literature, existing dashboards, and learners' dashboard experiences, and identified a list of information that should be provided by the dashboard. As a result, four categories including learning preparation, learning participation, interaction, and learning outcomes, and eleven sub-categories of dashboard information were extracted. The results suggest implications for the design of online dashboard for learner-centered learning.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.4
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• pp.343-350
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• 2017

The RC flat plate system has benefits such as a short construction time, an improvement of workability and a floor height reduction. In the case of long span slab, cracking damages and large deflections tend to occur due to the low flexural stiffness of flat plates. Specially, over-loading by self-weight of slab during construction increases short and long-term deflections. These problems may be solved by the use of void slab that has benefits of the reduced self-weight. In this study, to analyze an effect of self-weight reduction of void slab on slab deflections, the parametric study is performed. Including variable conditions such as a concrete strength, a slab construction cycle, the number of shored floors, a compressive reinforcement ratio and a tensile reinforcement ratio, slab construction loads and deflections are calculated by considering the construction stages, concrete cracking, and long-term effects. The short-term deflections during construction and the long-term deflections after construction of both of normal and void slabs are compared and the effects of void slab on the reduction of slab deflections are analyzed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.953-963
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• 1994

Treatment techniques of soft clay layers is needed sophisticated technology in civil engineering. Especially, dredged and reclaimed clay has high liquid limit and water content, so it is difficult to use. Now it comes to the applicability as good construction materials by predicting the behaviors. This paper is to evaluate the characteristics of sedimentation and self-weight consolidation of extremely soft clay, and is to find the way of applying model test result of reconstructing the in-situ condition to design. The consolidation properties of soft clay layers changing the size of the cell are investigated by large-scale consolidation test apparatus and the behaviors of self-weight consolidation are predicted by numerical analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.291-297
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• 2006

In this study, the equivalent physical properties of the shielded slot plate having a lot of very tiny bridge shape structures on its plane were determined by tensile tests and structural analyses. With those results, numerical analyses for the deflection profile by gravity effect were carried out to compare with experimental results. The two results were shown coincident very well so that the estimated equivalent physical properties were verified enough for further studies such as curvature reduction for the shielded slot plate.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.3
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• pp.122-133
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• 1999

Overlap, excessive wide gaps, and errors between blocks during erection process increases cost and man-hour. In this paper, a system to simulate the assembly process is suggested and a plane block assembly of welding deformation with gravity is simulated in consideration of assembly order, deformations and errors occurring in the cutting and forming processes are not considered and welding deformations are acquired by equivalent stiffness and load method from experiments and hull double bottom plane block is assembled on a assembly order by panel method. It is certified that according to the order of assembly, intermediate product shape affects rigidity which affects welding deformations. Assembly order must be considered in the assembly process. It is certified that the gravity has important role in the assembly process.

• Computational Structural Engineering
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• v.6 no.1
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• pp.91-98
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• 1993

Minimum weight design of the boom of an excavator with stress and displacement constraints was performed. The procedure of analysis consists of the following steps. The finite element model of the boom was built up by using 227 triangular plate elements each of which has three nodes. And then the finite element program was implemented and its accuracy was verified by comparing its results with those of the commercial structural analysis package-ANSYS 4.4A. For the constraints of stresses and displacements, the design sensitivities of those were computed using direct differentiation method. To verify the reliability of them the results were compared with those of the finite difference method. The optimum design value was obtained by using PLBA(Pshenichny-Lim-Belegundu-Arora)non-linear optimization program which adopts the active set strategy. Using the above results, minimum weight design of an excavator boom showed an effect of 27% reduction in weight.