• 한국전산구조공학회논문집
• /
• 제19권3호
• /
• pp.283-293
• /
• 2006

근래에 들어서 사회적 및 경제적인 요구에 의하여 건축구조물이 점차 고층화 및 대형화됨에 따라서 다양한 형식의 구조시스템이 연구 및 개발되고 있다. 비교적 최근에 개발된 초대형 골조시스템은 초대형부재의 조합으로 횡방향 강성을 충분히 발휘함으로써 초고층건물에 적합한 구조시스템으로 인식되고 있다. 그러나 이러한 초대형 골조시스템을 적용한 건물의 거동을 예측하기 위해서는 매우 많은 수의 절점과 요소로 이루어진 유한요소 모델을 해석해야 하므로 상당한 양의 해석시간과 엔지니어의 노력이 필요하게 된다. 따라서 본 연구에서는 초대형 골조시스템 전용 해석프로그램을 개발하여 초대형 골조구조물의 해석과 설계에 소요되는 시간과 노력을 줄이고자 한다. 이를 위하여 초대형 골조구조물의 특징을 활용한 효율적인 모형화기법과 행렬응축기법을 사용하여 해석에 사용되는 자유도수를 최소화도록 만든 해석모델이 개발되었다. 예제구조물의 해석을 수행하여 본 연구에서 개발된 프로그램을 사용한 결과와 일반적인 해석방법에 의한 결과와 비교함으로써 개발된 프로그램의 효율성과 정확성을 검증하였다.

• Composites Research
• /
• 제18권4호
• /
• pp.44-51
• /
• 2005

본 논문에서는 3차원 직교 직물 복합재료의 구성성분인 얀(Yarn)의 기하학적인 형상을 고려하여 직접수치모사(DNS) 모델을 개발하고 이를 이용하여 직교 직물 복합재료 평판의 저속충격 현상을 모사하였다. 미시구조를 보다 상세하고 정확하게 고려하기 위하여 토우 간격과 굴곡 등을 고려한 단위 구조를 제시하고 이를 이용하여 DNS 기반의 평판모델을 구현하였다. 정적 가상 실험을 통하여 얻은 DNS 모델의 거시적 등가 물성치를 바탕으로 한 거시기계학적 해석과의 비교하였고, DNS 모델을 이용하여 기존의 거시기계학적 모델에서 구현이 어려운 기하학적인 형상 차이에 따른 저속충격 현상의 영향을 고찰하였다. 그리고 보다 실제 실험에 가까운 가상 시편의 크기를 고려하고 해석의 효율성을 높이기 위하여 DNS개념에 기반한 멀티스케일 모델을 개발하여 거시/미시 해석 결과 특성을 함께 고찰하였다.

• 한국강구조학회 논문집
• /
• 제25권6호
• /
• pp.649-658
• /
• 2013

최근 건축 분야에서도 친환경, 순환형 패러다임으로 전환되어지고 있다. 이 연구에서는 사용자의 요구에 따라 구조체의 해체에 의해 재사용이 가능한 구조시스템을 도입하여 건설자재의 절감 및 재활용, 구조체의 장수명화를 통해 친환경 및 $LCCO_2$를 저감할 수 있는 강구조 시스템을 구현하고자 한다. 부재의 재조합이나 재사용을 가능하게 하기 위하여 탈착이 가능한 바닥슬래브와 강재보 접합상세를 제안하고 구조성능 및 진동 등과 같은 동적 특성에 의해 사용성을 파악하고 평가하였다.

• Earthquakes and Structures
• /
• 제10권5호
• /
• pp.1143-1179
• /
• 2016

Offshore wind turbines are considered as a fundamental part to develop substantial, alternative energy sources. In this highly flexible structures, monopiles are usually used as support foundations. Since the monopiles are large diameter (3.5 to 7 m) deep foundations, they result in extremely stiff short monopiles where the slenderness (length to diameter) may range between 5 and 10. Consequently, their elastic deformation patterns under lateral loading differ from those of small diameter monopiles usually employed for supporting structures in offshore oil and gas industry. For this reason, design recommendations (API and DNV) are not appropriate for designing foundations for offshore wind turbine structures as they have been established on the basis of full-scale load tests on long, slender and flexible piles. Furthermore, as these facilities are very sensitive to rotations and dynamic changes in the soil-pile system, the accurate prediction of monopile head displacement and rotation constitutes a design criterion of paramount importance. In this paper, the Fourier Series Aided Finite Element Method (FSAFEM) is employed for the determination of static impedance functions of monopiles for OWT subjected to horizontal force and/or to an overturning moment, where a non-homogeneous soil profile has been considered. On the basis of an extensive parametric study, and in order to address the problem of head stiffness of short monopiles, approximate analytical formulae are obtained for lateral stiffness $K_L$, rotational stiffness $K_R$ and cross coupling stiffness $K_{LR}$ for both rough and smooth interfaces. Theses expressions which depend only on the values of the monopile slenderness $L/D_p$ rather than the relative soil/monopile rigidity $E_p/E_s$ usually found in the offshore platforms designing codes (DNV code for example) have been incorporated in the expressions of the OWT natural frequency of four wind farm sites. Excellent agreement has been found between the computed and the measured natural frequencies.

• 한국의상디자인학회지
• /
• 제15권2호
• /
• pp.77-89
• /
• 2013

This study investigated the formation of silhouette and hemline shape of knit flare skirts according to the properties of knit material through virtual clothing with a 3D virtual clothing system called i-Designer of Technoa, thus building a database of the property data of knit material to reduce the number of sample making steps repeated and implemented several times in the process of clothes making. The results would help to estimate a silhouette in advance, offer assistance to the development of original knit wear, and explore ways to provide basic data for the development of the knit industry of the nation. The investigator made 12 kinds of experimental clothes to the angles(width of skirt: $90^{\circ}$ and $180^{\circ}$), gauge(7G, 12G, and 15G), and grain directions(wale and bias direction) of experimental clothes for virtual clothing. The dynamic characteristics of knit skirt samples according to each gauge were measured with the KES-FB system. Draper shapes were analyzed with the sectional shape data of hemline based on i-Designer. As for the measurements of the sectional shape of hemline and the formation of silhouette, the number of nodes, the average height of node mountains and valleys, and the hemline width right and left and before and after increased at the angle of $180^{\circ}$ than $90^{\circ}$. As gauges multiplied, the number of nodes, and silhouette angle dropping. When considering grain directions, the number of nodes and silhouette index increased in the wale direction at the angle of $90^{\circ}$ with the number of nodes and silhouette angle increasing in the wale direction at the angle of $180^{\circ}$.

• Structural Engineering and Mechanics
• /
• 제46권6호
• /
• pp.755-773
• /
• 2013

One of the main requirements of the seismic design codes must be its easy application by structural engineers. The use of practically-applicable models or simplified models as single-degree-of-freedom (SDOF) systems is a good alternative to achieve this condition. In this study, deterministic and probabilistic response transformation factors are obtained to evaluate the response in terms of maximum ductility and maximum interstory drifts of multi-degree-of-freedom (MDOF) systems based on the response of equivalent SDOF systems. For this aim, five steel frames designed with the Mexican City Building Code (MCBC) as well as their corresponding equivalent SDOF systems (which represent the characteristics of the frames) are analyzed. Both structural systems are subjected to ground motions records. For the MDOF and the simplified systems, incremental dynamic analyses IDAs are developed in first place, then, structural demand hazard curves are obtained. The ratio between the IDAs curves corresponding to the MDOF systems and the curves corresponding to the simplified models are used to obtain deterministic response transformation factors. On the other hand, demand hazard curves are used to calculate probabilistic response transformation factors. It was found that both approaches give place to similar results.

• 한국구조물진단유지관리공학회 논문집
• /
• 제14권6호
• /
• pp.117-123
• /
• 2010

일반적으로 고내구성 재료로 알려져 있는 FRP 재료가 유해한 환경요소에 노출될 경우 가수분해와 같은 화학적 반응으로 인하여 재료적 열화와 재료의 성질이 감소될 수 있다. 따라서, FRP 재료를 건설 주부재로 사용하기 위해서는 사용 환경에 따른 역학적 특성을 정확하게 파악하는 것이 중요하다. 이에 본 연구에서는 화학약품에 의한 급성 또는 만성적인 극심한 변화들을 가상적인 시뮬레이션을 실시하고자 강산과 강알칼리화합물 용액에 FRP 부재를 일정기간 보관한 후 압축강도, 인장강도, 전단강도 그리고 휨강도 실험을 실시하여 화학약품의 종류 및 보관일수에 따른 강도 변화를 분석하였다. 결론적으로 본 연구를 통하여 FRP 부재의 우수한 내화학약품성을 확인할 수 있었다.

• 국제초고층학회논문집
• /
• 제9권3호
• /
• pp.273-282
• /
• 2020

An innovative high-rise timber-concrete hybrid structure was proposed in previous research, which is composed of the concrete frame-tube structure and the prefabricated timber modules as main structure and substructures, respectively. Considering that the timber substructures are built on the concrete floors at a different height, the floor response spectrum is more effective in estimating the seismic response of substructures. In this paper, the floor response spectra of the hybrid structure with different structural parameters were calculated using dynamic time-history analysis. Firstly, one simplified model that can well predict the seismic response of the hybrid structure was proposed and validated. Then the construction site, the mass ratio and the frequency ratio of the main-sub structure, and the damping ratio of the substructures were discussed. The results demonstrate that the peaks of the floor response spectra usually occur near the vibration periods of the whole structure, among which the first two peaks stand out; In most cases, the acceleration amplification effect on substructures tends to be more evident when the construction site is farther from the fault rupture; On the other hand, the acceleration response of substructures can be effectively reduced with an appropriate increase in the mass ratio of the main-sub structure and the damping ratio of the substructures; However, the frequency ratio of the main-sub structure has no discernible effect on the floor response spectra. This study investigates the characteristics of the floor response spectrum of the novel timber-concrete structure, which supports the future applications of such hybrid structure in high-rise buildings.

• 한국컴퓨터정보학회:학술대회논문집
• /
• 한국컴퓨터정보학회 2010년도 제42차 하계학술발표논문집 18권2호
• /
• pp.485-491
• /
• 2010

The arrival of the Web 2.0 age, which is characterized by such key words as participation, sharing and openness, provides a learning environment in which both instructors and students can experience interactivity. In the educational area, we are particularly witnessing a growing interest in the social software like Wiki as one of the communication tools that reflects the characteristics of Web 2.0 and focuses on the interactivity with others. Based on this background, this study aims to examine into the meanings of interactivity inherent in the Wiki-based learning by studying such cases where Wiki is being used as a learning tool. For the purpose of our study, we practiced the Wiki-based learning method on the study subjects of the 17 junior students from U- University and 18 junior students from K- University during their 2009 fall semester teacher training courses. Through a comprehensive analysis of the questionnaires, interviews, Interactivity Measurement Diagram, examinations on the Wiki uses, Daily Self-reflection Records, and any other materials collected throughout the program, we could garner the following results: First, most of the students acknowledged that the use of Wiki was a useful communication means and helped promote their interactivity during their learning activities. Second, the interactivity of the Wiki-based learning was found to be more dynamic in the team-based projects or the community-based Wiki uses than in the instructor-oriented cases. Third, the Wiki-based learning is judged effective in expanding the scope of thinking and improving the learning capabilities through the collaborative knowledge-building process. The educational employment of the social software like Wiki in this web 2.0 age has great potentials for the true establishment of the learner-oriented learning environment, which has long remained at a standstill.

• 한국전산구조공학회논문집
• /
• 제27권4호
• /
• pp.231-238
• /
• 2014

건물의 경우, 용도 변경에 따른 중력하중 변화, 시공 단계에 따라 중력하중 변화 등이 구조물 시스템에 영향을 미친다. 따라서, 본 연구에서는 시스템 식별 변수 설정에 있어 기존에 강성만을 변수로 설정한 방법에 추가적으로 질량을 변수로 설정하여 시스템을 식별하는 기법을 제안한다. 계측한 동특성과 FE모델에서 추출한 동특성 간의 차이를 최소화하여 변수를 탐색하게 된다. 최소화 기법으로 변형 유전 알고리즘을 적용하였다. 보다 전역적 해탐색을 위해 변형 유전 알고리즘은 더 넓은 해 탐색 공간에서 해를 찾는다. 철골 보 구조물의 시뮬레이션을 통해 본 연구가 제시한 기법을 검증하였고 변형 유전 알고리즘과 기존의 단순 유전 알고리즘의 성능을 비교하였다. 또한, 강성 식별만을 수행한 기존 연구의 방법과 본 연구가 제시한 기법간의 차이를 비교하였다.