• Journal of the Korea Furniture Society
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• v.25 no.1
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• pp.1-10
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• 2014

The First bentwood chairs in the world, called "winsor chairs" were made by British craftsman in the 17th century. Since then, from the start of NO.14 using solid bentwood by 19th-century German Michael Thonet, furniture making techniques such as Bent knee, Y-leg, X-leg- were developed based on Llaminated bentwood made by Alvar Aalto of Finland in the 20th century. In the 20th century Charles Eames of the United States studied Molded plywood, using plywood to produce a variety of furniture and during the 17~20 century a variety of Bentwood were developed. Coming into the 21st century, American Matthias Pliessnig and Phil Seaton worked with past Bentwood designs, developing Bentwood further by adapting Bentwood's know-how and IT technology. Science and technology evolved and Reholz of Germany developed technology which can mold three-dimensional wood using a new matarial called 3D-veneer, In the past only plastic or metal could be moulded 3 dimensional but now beautiful wood grain patterns can be molded by utilizing this technology. Also this is comparable with the past two-dimensional molding technology. In this Sustainable Design techniauses era, Bentwood fused with IT technology has great potential as a high-tech and eco-friendly techniche.

• Steel and Composite Structures
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• v.13 no.2
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• pp.139-155
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• 2012

Serviceability rather than strength is the most critical design requirement for vibration-vulnerable floor constructions. Annoying vibrations due to normal walking activity have been observed more frequently on long-span lightweight floor systems in office and commercial retail buildings, raising the need for the development of floor vibration design procedures. This paper highlights some limitations of one of the most commonly used guidelines AISC/CISC DG11, and proposes improvements to this method. Design charts and approximate closed form formulas to estimate the walking response are developed in which various factors relating to the dynamic characteristics of both the floor and the excitation are considered. The accuracy of the proposed formulas and other proposals found in the literature is examined. The proposed modifications would be significant, especially with long-span floors where vibration levels may be underestimated by the current design procedure. The application of the proposed prediction method is illustrated by worked examples that reveal a good agreement with results obtained from finite element analyses and experiments. The presented work would enhance the accuracy and maintain the simplicity and convenience of the design guideline.

• Korean Medical Education Review
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• v.21 no.2
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• pp.80-91
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• 2019

The tripartite mission of 'academic medicine' is education, research, and patient care. Academic medical centers (AMCs) are carrying out the mission and ultimately aiming to improve the health of people and communities. Globally, AMCs are facing a tremendous financial risk stemming from the changes in health insurance reimbursement plans and a shortage of human resources. Innovative AMCs in the United States are trying to transform their physician-centered, and siloed structure into a patient-centered, and integrated structure. They are also building integrated systems with primary healthcare groups to provide continuous patient care from primary to tertiary levels and making strategic networks based on value-based payment and the patient-centered model. These changes have been proven to improve outcomes of patient care and increase fiscal revenues, which are both crucial in supporting education and research. To address the shortage of human resources, programs are being built to develop newly appointed faculty for the future. AMCs have different approaches to bringing changes into their organizations; however, there is a common emphasis on 'a patient-centered approach,' which helps them set more explicit organizational values and make strategic decisions based on their values. Korean AMCs are facing similar challenges to AMCs in the United States in spite of many differences between the countries' healthcare systems. The innovative efforts of AMCs in the United States to address the challenges will be helpful, well-worked examples for Korean AMCs with similar challenges.

• School Mathematics
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• v.19 no.2
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• pp.289-317
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• 2017

This study aims to explore how Korean middle-school mathematics textbooks on functions provide students an opportunity-to-learn [OTL]. For this purpose, we investigate 3 textbooks in terms of mathematics content and practice, the level of cognitive demands of mathematical tasks, types of student responses, types of context-based tasks, and connections among the tasks. The findings from the data analysis suggest as follows: a) an opportunity-to-learn to connect procedures to functional concepts and new ideas of functions to the existing one is very limited; b) the textbooks seem to provide students an OTL to understand functions as definitions, rules and conventions and to experience repeatedly procedural executions through worked examples and mathematics tasks; c) students may not experience to explain their own ideas/thinking by using mathematical sentence or justify their own cognitive processes; and d) students can be exposed to get a sense of mathematics as a set of fragmented and isolated facts or procedures, rather than to encourage to expand and deepen their understanding of functions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.1
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• pp.23-31
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• 1987

This work presents an optimality criteria method which gives accurate solution to the structural optimization problem of plane frames subject to displacement and stress constraints. The method is made efficient, as well as rigorous, by including only the lateral displacement of the top floor in the set of behavioral constraints. The bending stresses of members are treated as side constraints based on the concept of fully-stressed-design, but the optimality of the final design is tested by treating them as behavioral constraints and examining if the design satisfies this new optimality criteria. Worked examples show the superiority of the rigorous opimality criteria in spite of its being simple and efficient.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.5
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• pp.31-42
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• 2003

This study looked at worked on remaining landscapes in terms of landscape ecology. It presented some ways to conserve and to activate remaining landscapes with examples of agricultural lands in Hwa-won Gun, Ok-po Myun. The results are as follows: We investigated 20 remaining landscape types and 90 remaining landscapes, and classified them in terms of forest and water zones. To evaluate the investigated remaining landscapes, we produced a grading system using 8 criteria such as vitality, stability, field suitability, type of inner scenery formation, connection, recreation, and culture/tradition. Our evaluation of the vitality found that Grade I had the mast remaining landscapes; Grade II had 28, Grade III had 16, Grade V had four, and Grade IV had none. We evaluated the outer landscape influence using 3 criteria such as divisibility, vitality, and indication. We found from evaluating the type of inner scenery formation that most of the landscapes superior to Grade III were adjacent to water zones and that linear landscapes evaluated as Grade I, and II played an important role in this connection. We evaluated the recreation probability using marks, frequencies, and emergencies of peculiar types. Based on the results, we proposed some ways to conserve and to activate the remaining landscapes classified by grades using the results of the last evaluation. Additionally, we proposed some ways to activate the restoration of the linear axis of the green space function the formation of a buffer green space around matric space, the improvement of the axis of the green space center, and the formation of additional green tracts of land to play the role of stepping stones. We proposed the possibility of improving uniformed farm land structures. This study did not consider the weighting values of the evaluation index. Therefore a more objective study will be needed with an expert-survey in the future.

• Structural Engineering and Mechanics
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• v.22 no.6
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• pp.665-683
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• 2006

The strength behaviors of Fiber Reinforced Plastics (FRP) Composites can be greatly influenced by the properties of constitutive materials, the laminate structures, and load conditions etc, accompanied by many uncertainty factors. So the reliability study on FRP is an important subject of research. Many achievements have been made in reliability studies based on the probability theory, but little has been done on the roles played by fuzzy variables. In this paper, a fuzzy reliability model for FRP laminates is established first, in which the loads are considered as random variables and the strengths as fuzzy variables. Then a numerical model is developed to assess the fuzzy reliability. The Monte Carlo simulation method is utilized to compute the reliability of laminas under the maximum stress criterion. In the second part of this paper, a generalized fuzzy reliability model (GFRM) is proposed. By virtue of the fact that there may exist a series of states between the failure state and the function state, a fuzzy assumption for the structure state together with the probabilistic assumption for strength parameters is adopted to construct the GFRM of composite materials. By defining a generalized limit state function, the problem is converted to the conventional reliability formula that enables the first-order reliability method (FORM) applicable in calculating the reliability index. Several examples are worked out to show the validity of the models and the efficiency of the methods proposed in this paper. The parameter sensitivity analysis shows that some of the mean values of the strength parameters have great influence on the laminated composites' reliability. The differences resulting from the application of different failure criteria and different fuzzy assumptions are also discussed. It is concluded that the GFRM is feasible to use, and can provide an effective and synthetic method to evaluate the reliability of a system with different types of uncertainty factors.

• Geomechanics and Engineering
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• v.19 no.6
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• pp.499-511
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• 2019

The reliability of reinforced concrete structures is frequently compromised by the deterioration caused by reinforcement corrosion. Evaluating the effect caused by reinforcement corrosion on structural behaviour of corrosion damaged concrete structures is essential for effective and reliable infrastructure management. In lifecycle management of corrosion affected reinforced concrete structures, it is difficult to correctly assess the lifecycle performance due to the uncertainties associated with structural resistance deterioration. This paper presents a stochastic deterioration modelling approach to evaluate the performance deterioration of corroded concrete structures during their service life. The flexural strength deterioration is analytically predicted on the basis of bond strength evolution caused by reinforcement corrosion, which is examined by the experimental and field data available. An assessment criterion is defined to evaluate the flexural strength deterioration for the time-dependent reliability analysis. The results from the worked examples show that the proposed approach is capable of evaluating the structural reliability of corrosion damaged concrete structures.

• Computational Structural Engineering
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• v.9 no.2
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• pp.121-131
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• 1996

This work proposes an optimality criteria applicable to the optimum design of plane frames subject to multiple behavioral constraints on member stresses and lateral displacements of nodes and also to side constraints on design variables. The method makes use of a first order approximation for both deflection and stress constraints instead of the zero order approximation based on the concept of FSD (fully stressed design). A redesign algorithm is derived from a mathematically rigorous method which uses the Newton-Raphson method to solve the system of nonlinear constraint equations and reduces the design space whenever minimum size restrictions become active. When applied to worked examples it proved more accurate and efficient, and it is often found that optimum designs are not fully stressed designs. This fact suggests that this rigorous method is worth what it claims for complicated computing and thus had better replace the crude stress ratio algorithm adopted by the majority of optimality criteria approaches. This is particularly true as long as we enjoy ever-increasing computing power at negligible costs.

• Geomechanics and Engineering
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• v.6 no.6
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• pp.517-530
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• 2014

Seismic ground response analysis is one of the most important issues in geotechnical earthquake engineering. Conventional seismic site response and free field analysis of layered soils does not consider the effect of surcharge mass which may be present on the top layer. Surcharge mass may develop extra inertial force to the soil and, hence, significantly affect on the results of seismic ground response analysis. Methods of analysis of ground response may also be categorized into time domain and frequency domain concepts. Simplicity in developing analytical relations and accuracy in considering soil dynamic properties dependency to loading frequency are benefits of frequency domain analysis. In this part of the paper, seismic ground response is analyzed using transfer function method for soil layers considering surcharge mass on the top layer. Equation of motion, wave equation, is solved using amended boundary conditions which effectively take the impact of surcharge mass into account. A computer program is developed by MATLAB software based on the solution method developed for wave equation. Layered soils subjected to earthquake loading were numerically studied and solved especially by the computer program developed in this research. Results obtained were compared with those given by DEEP SOIL computer program. Such comparison showed the accuracy of the program developed in this study. Also in this part, the effects of geometrical and mechanical properties of soil layers and especially the impact of surcharge mass on transfer function are investigated using the current approach and the program developed. The efficiency and accuracy of the method developed here is shown through some worked examples and through comparison of the results obtained here with those given by other approaches. Discussions on the results obtained are presented throughout in this part.