• Structural Engineering and Mechanics
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• v.48 no.1
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• pp.57-75
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• 2013

It is still inadequate for investigating the highly nonlinear and complex mechanical behaviors of single-layer latticed domes by only performing a force-based demand-capacity analysis. The energy-based balance method has been largely accepted for assessing the seismic performance of a structure in recent years. The various factors, such as span-to-rise ratio, joint rigidity and damping model, have a remarkable effect on the load-carrying capacity of a single-layer latticed dome. Therefore, it is necessary to determine the maximum load-carrying capacity of a dome under extreme loading conditions. In this paper, a mechanical model for members of the semi-rigidly jointed single-layer latticed domes, which combines fiber section model with semi-rigid connections, is proposed. The static load-carrying capacity and seismic performance on the single-layer latticed domes are evaluated by means of the mechanical model. In these analyses, different geometric parameters, joint rigidities and roof loads are discussed. The buckling behaviors of members and damage distribution of the structure are presented in detail. The sensitivity of dynamic demand parameters of the structures subjected to strong earthquakes to the damping is analyzed. The results are helpful to have a better understanding of the seismic performance of the single-layer latticed domes.

• Architectural research
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• v.20 no.2
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• pp.53-64
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• 2018

A nonlinear analytical model has been proposed for two-span two-story reinforced concrete frames with relaxed section details. The analytical model is composed of beam, column, and beam-column joint elements. The goal of this study is to develop a simple and light nonlinear model for two-dimensional reinforced concrete frames since research in earthquake engineering is usually involved in a large number of nonlinear dynamic analyses. Therefore, all the nonlinear behaviors are modeled to be concentrated on flexural plastic hinges at the end of beams and columns, and the center of beam-column joints. The envelope curve and hysteretic rule of the nonlinear model for each element are determined based on experimental results, not theoretical approach. The simple and light proposed model can simulate the experimental results well enough for nonlinear analyses in earthquake engineering. Consequently, the proposed model will make it easy to developing a nonlinear model of the entire frame and help to save time to operate nonlinear analyses.

• Computers and Concrete
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• v.8 no.1
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• pp.23-41
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• 2011

The behaviour of concrete confined by transverse reinforcement is a classical topic. Numerous studies have been conducted to establish the stress-strain relationships for concrete under various confining reinforcement arrangements. Many empirical and semi-empirical formulas exist. Simplified analytical models have also been proposed to evaluate the increase in the strength and ductility of confined concrete. However, relatively few studies have been conducted to utilise advanced computational models for a realistic simulation of the behaviour of concrete confined by transverse reinforcement. As a matter of fact, high fidelity simulations using the latest numerical solvers in conjunction with advanced material constitutive models can be a powerful means to investigating the mechanisms underlying the confining effects of different reinforcement schemes. This paper presents a study on the use of high fidelity finite element models for the investigation of the behaviour of concrete confined by stirrups, as well as the interpretation of the numerical results. The development of the models is described in detail, and the essential modelling considerations are discussed. The models are then validated by simulating representative experimental studies on short columns with different confining reinforcement schemes. The development and distribution of the confining stress and the subsequent increase in the axial strength are examined. The models are shown to be capable of reproducing the behaviour of the confined concrete realistically, paving a way for systematic parametric studies and investigation into complicated confinement, load combination, and dynamic loading situations.

• Journal of the Korea Computer Graphics Society
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• v.10 no.2
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• pp.42-50
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• 2004

캐릭터 애니메이션 기술의 발달로 가상공간에 애니메이트되는 캐릭터의 수가 점점 증가되고 있으며, 캐릭터 자체 골격구조의 관절 개수와 캐릭터를 덮고 있는 메쉬의 폴리곤 개수도 점점 증가하는 추세이다. 따라서, 실시간 가상환경에서 다수의 캐릭터를 전처리 과정 없이 시뮬레이션할 경우 전체 군중시스템 성능의 저하가 예상된다. 본 논문에서는, 이러한 문제점을 해결하기 위해 모션 다단계(motion level-of-detail) 기법을 제시한다. 모션 단순화 기법은 캐릭터의 움직임을 제어하는 골격(관절)구조와 캐릭터의 형태를 시각적으로 표현하는 기하(메쉬)구조를 단순화 하는 방법으로 기존 동작과 단순화된 동작의 차이를 최소화 한다. 골격구조 단순화를 위한 JPC(joint posture clustering)방법은 특정 관절의 연속된 모션 시퀀스에서의 유사 자세 집단을 추출하여 하나의 자세로 표현하는 방법으로, 모션의 특성에 따라 동적으로 관절을 단순화하여 관절 시뮬레이션 시간을 줄이는 방법이다. JPC방법은 골격구조가 시간에 따라 동적으로 변형되기 때문에 골격구조의 계층구조를 재 구축할 시간이 필요하지만, 기존 동작과 유사성을 잃지 않는 단순화된 동작 생성이 가능하다. 유사 자세 집단을 추출하기 위해 전체 모션 시퀀스에서 관절의 프레임간 자세 차이를 수식화하여 테이블 형태로 구성하고 이를 통해 기존 동작의 유사성을 잃지 않으며 관절의 단순화 율을 최대화 할 수 있는 알고리즘을 제시한다. 또한, 실시간 군중 환경의 성능을 더욱 향상시키기 위해 시간에 따라 변형되는 캐릭터 메쉬의 단순화 기법을 적용한다. 실험결과 모션 다단계 기법은 실시간 군중환경에서 캐릭터의 수가 많고 복잡한 골격구조와 기하구조로 구성된 관절 궤적의 변화가 심하지 않은 동작에 대해 특히 효율적이다.

• Journal of muscle and joint health
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• v.27 no.2
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• pp.132-141
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• 2020

Purpose: This study aimed to analyze factors affecting the handwashing performance of nursing students using the health belief model, self-efficacy, and handwashing attitudes. Methods: Data were collected using structured questionnaires in 2018. 223 students enrolled in nursing college participated in the questionnaire, which consisted of four sections: health belief in hand washing, self-efficacy, hand washing attitude, and general handwahsing characteristics. Data were analyzed using t-test, ANOVA, correlation coefficient and multiple regression analysis with SPSS 21.0 statistical programs. Results: The significant predictors affecting proper hand cleansing were perceived benefits and motivation of health belief model, handwashing time and frequency, and handwashing attitude. Out of these significant variables, perceived benefits was shown to be the strongest predictor. Conclusion: The findings suggest that periodic and steady hand washing training programs need to be implemented in order to improve handwashing practices of nursing students. Such handwashing education programs should include content that sensitizes the benefits of hand washing and provides information on how to carry out hand washing in detail.

• Structural Engineering and Mechanics
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• v.54 no.3
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• pp.521-543
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• 2015

Depending on the damage type as well as the level of damage observed after the earthquake, certain measures should be taken for the damaged buildings. In this study, structural repairing of two different types of damaged RC beam-column assembly by carbon fiber-reinforced polymer sheets is investigated in detail as a member repairing technique. Two types of 1:1 scale test specimens, which represent the exterior RC beam-column connection taken from inflection points of the frame, are utilized. The first specimen is designed according to the current Turkish Earthquake Code, whereas the second one represents a deficient RC beam-column assembly. Both of the specimens were subjected to cyclic quasistatic loading in the laboratory and different levels of structural damage were observed. The first specimen displayed a ductile response with the damage concentrated in the beam. However, in the second specimen, the beam-column joint was severely damaged while the rest of the members did not attain their capacities. Depending on the damage type of the specimens, the damaged members were repaired by CFRP wrapping with different configurations. After testing the repaired specimens, it is found that former capacities of the damaged members were mostly recovered by the application of CFRPs on the damaged members.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.314-328
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• 2019

This paper attempts to combine the pneumatic breakwater and submerged breakwater to increase the effectiveness of wave damping for long-period waves. A series of physical experiments concerning pneumatic breakwater, submerged breakwater and their joint breakwater was conducted and used to validate a mathematical model based on Reynolds-averaged Navier-Stokes equations, the RNG $k-{\varepsilon}$ turbulence model and the VOF method. In addition, the mathematical model was used to investigate the wave transmission coefficients of three breakwaters. The nonlinear wave propagation behaviors and the energy transfer from lower frequencies to higher frequencies after the submerged breakwater were investigated in detail. Furthermore, an optimal arrangement between pneumatic breakwater and submerged breakwater was obtained for damping longer-period waves that cannot be damped effectively by the pneumatic breakwater alone. In addition, the reason for the appearance of the combination effect is that part of the energy of the transmitted waves over the submerged breakwater transfers to shorter-period waves. Finally, the impact of the joint breakwater on the wave field during wave propagation process was investigated.

• Steel and Composite Structures
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• v.38 no.3
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• pp.319-336
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• 2021

To achieve a rational detail of the girder-abutment joints in composite integral bridges, and validate the performance of the joints with perfobond connectors, this paper proposes two innovative types of I-shaped steel girder-concrete abutment joints with perfobond connectors intended for the most of bearing capacity and the convenience of concrete pouring. The major difference between the two joints is the presence of the top flange inside the abutments. Two scaled models were investigated with tests and finite element method, and the damage mechanism was revealed. Results show that the joints meet design requirements no matter the top flange exists or not. Compared to the joint without top flange, the initial stiffness of the one with top flange is higher by 7%, and the strength is higher by 50%. The moment decreases linearly in both types of the joints. At design loads, perfobond connectors take about 70% and 50% of the external moment with and without top flange respectively, while at ultimate loads, perfobond connectors take 53% and 26% of the external moment respectively. The ultimate strengths of the reduced sections are suggested to be taken as the bending strengths of the joints.

• Journal of Korean Society of Steel Construction
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• v.24 no.5
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• pp.491-501
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• 2012

Generally, a steel pier-foundation has been designed and constructed with a anchor frame. However, because of the complicated design and construction, the foundation's size has become large and has been overdesigned. In this study, three specimens were made and the tests were conducted to suggest a new shape in regard to the pier-foundation's joint details using the high performance steel. One of the specimens was made up of the general anchors and the anchor frame. Another specimen consisted of the high tension anchors and the studs, and the other specimen was composed of the high tension anchors and the inner steels. After the performance of each specimen was compared and analyzed, the behavior characteristics according to the joint were analyzed.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.3
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• pp.45-52
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• 2011

It is known that test methods to evaluate solder joint reliability are die shock test, die shear test, 3points bending test, and thermal shock test. The present study investigated the effects of failure mode on 3 types (as-reflowed, $85^{\circ}C$/85%RH treatment, and $150^{\circ}C$/10hr aging) of solder joints for flip-chip BGA package by using various test methods. The test methods and configurations are reported in detail, i.e. die shock, die shear, 3points bending, and thermal shock test. We focus on the failure mode of solder joints under various tests. The test results indicate that die shock and die shear test method can reveal brittle fracture in flip-chip ball grid array (FCBGA) packages with higher sensitivity.