• 한국가구학회지
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• 제25권1호
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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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• 제13권2호
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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.

• 의학교육논단
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• 제21권2호
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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.

• 대한수학교육학회지:학교수학
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• 제19권2호
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• pp.289-317
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• 2017

이 연구에서는 우리나라 중학교 수학 교과서의 함수 단원에서 학생에게 어떠한 학습 기회를 제공하는지를 탐색한다. 구체적으로, 교과서가 제시하는 수학 내용과 실행, 수학 과제의 인지적 노력수준, 학생 응답의 유형, 문제 상황의 형태 및 특징 등의 측면을 탐구하여서 교과서가 학생들에게 어떠한 학습기회를 제안하며 구조화하는가를 살펴본다. 이를 위해서 2009 개정 교육과정에 따른 중학교 수학교과서 3종을 분석하였다. 그 결과로 교과서가 학생에게 제공하는 함수에 대한 학습기회는 다음과 같이 요약된다. 첫째, 절차적 지식과 개념 간의 연결성이 매우 약하며 함수의 내용 간의 의미를 연결하는 기회가 매우 제한되어 있다. 둘째, 학생들은 함수를 정의, 규칙, 법칙만으로 학습하게 되며 예제와 수학과제를 통해서 계산의 절차 수행을 반복적으로 경험하게 될 가능성이 크다. 셋째, 학생들은 문제를 해결하는 과정에 대해서 수학적으로 설명하거나 추론하는 과정을 경험할 가능성이 매우 적다. 넷째, 수학과제와 상황과제를 통해 학생의 인지적 사고 과정이 확장되거나 심화되기 보다는 분절적이고 파편화된 지식으로 받아들일 수 있는 여지가 많다.

• 대한토목학회논문집
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• 제7권1호
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• pp.23-31
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• 1987

본(本) 연구(硏究)는 처짐과 응력제약(應力制約)을 받는 평면(平面)뼈대의 정확(正確)한 최적설계(最適設計)를 얻을 수 있는 Optimality Criteria 방법(方法)을 제시(提示)하고 있다. 여기서 평면(平面) 뼈대의 맨 윗층의 횡변위(橫變位)만을 거동적(擧動的) 제약(制約)에 포함(包含)시킴으로써 수학적(數學的)으로 엄격(嚴格)하면서도 효율적(効率的)인 방법(方法)이 되도록 하였다. 부재(部材)의 휨응력(應力)은 fully-stressed-design의 개념(槪念)에 근거(根據)하여 부차적(副次的) 제약(制約)으로만 취급(取扱)되었으나 최종설계(最終設計)의 최적성(最適性)을 判별(判別)하기 위하여 최종(最終) 단계(段階)에서 이들을 모두 거동적(擧動的) 제약(制約)으로 취급(取扱)한 새로운 Optimality Criteria를 유도(誘導)하고 이의 만족(滿足) 여부(與否)를 알아 보도록 하였다. 이 방법(方法)은 단순(單純)하고 효율적(効率的)이면서도 엄격(嚴格)한 Optimality Criteria를 채용(採用) 함으로써 보다 나은 설계(設計)를 구(求)할 수 있음을 예제(例題)를 통(通)하여 보였다.

• 한국조경학회지
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• 제31권5호
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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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• 제22권6호
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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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• 제19권6호
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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.

• 전산구조공학
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• 제9권2호
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• pp.121-131
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• 1996

본 연구는 부재의 응력, 절점의 횡변위 등 거동적 제약과 설계변수에 가해지는 부차적 제약을 받는 평면뼈대 구조물의 설계에 적용할 수 있는 최적규준을 제안하고자 하는 것이다. 변위 및 응력제약 모두에 1차 근사법을 적용하며 이는 전응력 설계방법과 다른 점이다. 비선형인 제약조건식을 푸는데 Newton-Raphson방법을 이용하고 최소치수 제약과 관련하여 설계공간을 축소하는 등 수학적으로 엄밀한 방법으로 재설계 알고리즘을 유도하였다. 적용 예를 통하여 이 방법이 정확한 방법임이 입증되었으며 전응력 설계가 최적설계가 되지 못하는 경우도 종종 발견되었다. 이 방법은 복잡한 계산과정 만큼 그 이용가치가 있으며 단순한 응력비 알고리즘을 이용하는 대부분의 최적규준 방법에 대치되어야 할 것이다. 특히, Computer의 지속적인 발전은 이 방법의 보편적인 이용을 가능하게 할 것이다.

• Geomechanics and Engineering
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• 제6권6호
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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.