• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.13 no.5
• /
• pp.99-107
• /
• 1993

In this study, material nonlinear finite element program is developed to analyze reinforced concrete shell of arbitrary geometry considering tension stiffening effects. This study is capable of tracing the load-deformation response and crack propagation, as well as determining the internal concrete and steel stresses through the elastic, inelastic and ultimate ranges in one continuous computer analysis. The cracked shear retention factor is introduced to estimate the effective shear modulus including aggregate interlock and dowel action. The concrete is assumed to be brittle in tension and elasto-plastic in compression. The Drucker-Prager yield criterion and the associated flow rule are adopted to govern the plastic behavior of the concrete. The reinforcing bars are considered as a steel layer of equivalent thickness. A layered isoparametric flat finite element considering the coupling effect between the in-plane and the bending action was developed. Mindlin plate theory taking account of transverse shear deformation was used. An incremental tangential stiffness method is used to obtain a numerical solution. Numerical examples about reinforced concrete shell are presented. Validity of this method is studied by comparing with the experimential results of Hedgren and the numerical analysis of Lin.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.5
• /
• pp.1543-1551
• /
• 1996

The static tensile load bearing capability of as adhesively-bonded tubular single lap jint that is calculated usign the linear mechanical properties of adhesive is usually far from the experimentally determined because the majority of the load transfer of the adhesively-bonded jointd is accomplished by the nonlinear behavior of the rubber-toughened eoxy adhesive. In this paper, both the nonlinear mechanical properties and the fabrication residual thermal stresses of adhesive were included in the calculation of the stresses of adhesively-bonded joints. The onlinear tensile properties of adhesive were approximated by an exponential form which was represented by the initial tensile modulus and ultimate tensile stength of adhesive. The stress distribution in the adhesive were calculated by applying the load obtained from the tensile tests. From the tensile tests and the stress analysis of adhesively-bonded hoints, the failure model for adhesively-bonded tubular single lap joints was proposed.

• Archives of design research
• /
• v.19 no.4 s.66
• /
• pp.145-154
• /
• 2006

In today's brand apartment ads, the image of high-tech apartment seeking consumers' convenience thanks to the introduction of ubiquitous and the image of nature-friendly apartment stressing consumers' well-being life have become a main stream. However, it seems that there lacks differentiation in expressing ad images, except some brands. This may also be related to the matter of providing effective communication, which is the ultimate goal of advertisement. Therefore, to suggest the effective communication methods of brand apartment ads, this study semiologically translated first the images thai recent brand apartment ads present, and then in order to review whether these images are properly delivered to consumers, this study conducted the image survey for brand apartment ads with 123 subjects, who are the group of design professionals. As a result, the survey showed that, in the semiological translation of ad expression, meaning sharing is made when ad concept and ad image are semiologically consistent, and it showed that the realization of successful ad communication between advertisers and consumers is possible, which starts from this kind of meaning sharing. Based on the results of this study, we could know that the introduction of semiology into ad planning can be a logical judgment criterion to provide effective ad communication.

• Structural Engineering and Mechanics
• /
• v.63 no.5
• /
• pp.617-628
• /
• 2017

In order to study the failure mode and seismic behavior of the interior-joint in steel traditional-style buildings, a single beam-column joint and a double beam-column joint were produced according to the relevant building criterion of ancient architectural buildings and the engineering instances, and the dynamic horizontal loading test was conducted by controlling the displacement of the column top and the peak acceleration of the actuator. The failure process of the specimens was observed, the bearing capacity, ductility, energy dissipation capacity, strength and stiffness degradation of the specimens were analyzed by the load-displacement hysteresis curve and backbone curve. The results show that the beam end plastic hinge area deformed obviously during the loading process, and tearing fracture of the base metal at top and bottom flange of beam occurred. The hysteresis curves of the specimens are both spindle-shaped and plump. The ultimate loads of the single beam-column joint and double beam-column joint are 48.65 kN and 70.60 kN respectively, and the equivalent viscous damping coefficients are more than 0.2 when destroyed, which shows the two specimens have great energy dissipation capacity. In addition, the stiffness, bearing capacity and energy dissipation capacity of the double beam-column joint are significantly better than that of the single beam-column joint. The ductility coefficients of the single beam-column joint and double beam-column joint are 1.81 and 1.92, respectively. The cracks grow fast when subjected to dynamic loading, and the strength and stiffness degradation is also degenerated quickly.

• Geomechanics and Engineering
• /
• v.11 no.1
• /
• pp.141-160
• /
• 2016

This study elucidates the uplift behaviors of the straight-sided and belled shafts. The field uplift load tests were carried out on 18 straight-sided and 15 belled shafts at the three collapsible loess sites under an arid environment on the Loess Plateau in Northwest China. Both the site conditions and the load tests were documented comprehensively. In general, the uplift load-displacement curves of the straight-sided and belled shafts approximately exhibited an initial linear, a curvilinear transition, and a final linear region, but did not provide a well defined peak or asymptotic value of the load, and therefore their uplift resistances should be interpreted from the load test results using an appropriate criterion. Nine representative uplift resistance interpretation criteria were used to define the "interpreted failure load" for each of the load tests, and all of these interpreted uplift resistances were normalized by the failure threshold, $T_{L2}$, obtained using the $L_1-L_2$ method. These load test data were compared statistically and graphically. For the straight-sided and belled shafts, the normalized uplift load-displacement curves were respectively established by the plots that related the mean interpreted uplift resistance ratio against the mean displacement at the corresponding interpreted criteria, and the comparisons of the normalized load-displacement curves were made. Specific recommendations for the designs of uplift belled and straight-sided shafts in the loess were given, in terms of both capacity and displacement.

• Hwankyungkyoyuk
• /
• v.13 no.1
• /
• pp.65-74
• /
• 2000

Environmentally literated students and adults should be able to use and apply the basic ecological concepts when considering environmental problems and issues. Because ecology forms the foundation of environmental education, a review of the literatures on the degree of students' understanding for ecological concepts can provide useful insights for environmental educators. The purposes of this study were as follows: first, to analyse the parts connected with ecological knowledge of two environmental education books, ‘environments’(middle school) and ‘environmental science’(high school), second, to investigate the level of understanding on ecological concepts by the use of new developed instrument. The 20 most important ecological concepts from Cherrett(1989) and the important ecological concepts' lists from Hungerford and Volk(1990), Ramsey, Hungerford and Volk(1992), Volk(1993) would be recognized and endorsed by most environmental educators as concepts essential to environmental literacy, We referenced these informations and sequenced ecological knowledge as four main categories(communities, populations, ecosystem, man as a component of the nature systems). We have used it as a criterion in the analysis of teaching materials and the development of a new test instrument($\alpha$=0.81). According to the analysed results, the understanding levels for scales and relationships of communities, populations, ecosystem were high but those for individual concepts and differences were low. By the analysis of Korean High School EE book, ‘environmental science’, learning for some concepts(succession, material cycling, niche etc.) has pointed out as one of problems. Environmental educators must pay a careful attention to the concepts that showed high rates of incorrect answer and this work will contribute toward consolidating the basis of EE and help the accomplishment of the ultimate goals in EE.

• Structural Engineering and Mechanics
• /
• v.82 no.1
• /
• pp.121-131
• /
• 2022

The main goal of this study is to prepare a program for analyzing High Strength Steel Fibrous Reinforced Concrete (HSSFRC) slabs and predict the response and strength of the slab instead of preparing a prototype and testing it in the laboratory. For this purpose, new equations are proposed to represent the material properties of High Strength Steel Fibrous Reinforced Concrete. The proposed equations obtained from performing regression analysis on many experimental results using statistical programs. The finite element method is adopted for non-linear analysis of the slabs. The eight-node "Serendipity element" (3 DoF) is chosen to represent the concrete. The layered approach is adopted for concrete elements and the steel reinforcement is represented by a smeared layer. The compression properties of the concrete are modeled by a work hardening plasticity approach and the yield condition is determined depending on the first two stress invariants. A tensile strength criterion is adopted in order to estimate the cracks propagation. many experimental results for testing slabs are compared with the numerical results of the present study and a good agreement is achieved regarding load-deflection curves and crack pattern. The response of the load deflection curve is slightly stiff at the beginning because the creep effect is not considered in this study and for assuming perfect bond between the steel reinforcement and the concrete, however, a great agreement is achieved between the ultimate load from the present study and experimental results. For the models of the tension stiffening and cracked shear modulus, the value of Bg and Bt (Where Bg and Bt are the curvature factor for the cracked shear modulus and tension stiffening models respectively) equal to 0.005 give good results compared with experimental result.

• Journal of Korean Academy of Nursing
• /
• v.30 no.1
• /
• pp.60-71
• /
• 2000

This research is a field investigation to collect basic information about the safe and efficient use of physical restraint in hospitals and for the ultimate minimization of restraint use. The objects of this study were sixty-four patients. They were restrained physically. Add their 32 family members, 24 nurses of two university hospitals in Seoul were also involved in the study. From April 16, to May 27, 1999. Research data were collected throughout the observation and interview process. Also, the data was analyzed using frequencies and field study notes that were invented by researchers. Results of this study were as follows: 1. According to the sex and age distinction; male's restraint use was 75%, female's was 25% and pre-schoolage children 39.1%, middle age 26.5%, and senior citizens 20.3%. According to the disease distinction; neuro-system was 35.9%, respiratory system was 21.9%. In the Ward, 40.6% of ICU patients were restrained and 39.0% of pediatric ward children were also to restraint. 70.3% of patients were restrained under 5days, while 10.9% were restrained 10days. 2. Types of physical restraints were wrist restraint (45.21%), arm board (35.62%), leg restraint (8.22%), chest restraint (6.85%), elbow restraint (2.74%) and mitten restraint (1.37%). 3. The percentage was 3.5%, which was in 64 restrained out of 1828 hospitalized people. At 1st investigation, the ratio was 3.5%, the 2nd was 3.0% and the 3rd was 3.9%. 4. The reasons of using the physical restraint were 'to protect implements' (72.84%), 'to protect patients' (18.52%), 'to protect an operative site' (8.64%). 5. The result of the patients; family and nurses' response analysis was: 'It seems to be safe', 'It uses properly', 'It is convenient for relatives and nurses', 'It is helpful to treatment', 'Objective think it is not restraint' were 79.9%. 'It is discomfort and stuffy', 'The implement is ineffective' were 21.1%. However in interview of the patients who can do verbally communication, 6 of 7 was responded that 'It is stuffy and uncomfortable'. 6. When restraint is used, the main decision is usually made by the nurses 42.2% of the time. The statistics read as thus: nurses and the physician in charge 31.3%, nurses and family 12.5%, physician's order 7.8%, only family 6.2%. Although the record of restraint was only 15.6% so that only 10 cases out of all the 26 ICU patients restrained. This study shows that physical restraints which of infringe independent-right of patients, are used without using criterion, explaining the agreement. Also, subjective decision of physician, nurses, and family make the decision of using restraint. So development of practice manuals and rules for restraint implementation is urgent.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.15 no.3
• /
• pp.491-499
• /
• 2002

A p-version finite element model based on degenerate shell element is proposed tot the analysis of orthotropic laminated plates. In the nonlinear formulation of the model, the total Lagrangian formulation is adopted with large deflection and moderate rotation being accounted tot in the sense of yon Karman hypothesis. The material model is based on the Huber-Mises yield criterion and Prandtl-Reuss flow rule in accordance with the theory of strain hardening yield function, which is generalized lot anisotropic materials by introducing the parameters of anisotropy. The model is also based on extension of equivalent-single layer laminate theory(ESL theory) with shear deformation, leading to continuous shear strain at the interface of two layers. The integrals of Legendre polynomials are used for shape functions with p-level varying from 1 to 10. Gauss-Lobatto numerical quadrature is used to calculate the stresses at the nodal points instead of Gauss points. The validity of the proposed P-version finite element model is demonstrated through several comparative points of iew in terms of ultimate load, convergence characteristics, nonlinear effect, and shape of plastic tone.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.1
• /
• pp.9-20
• /
• 2019

The number of natural disasters in Korea, such as earthquakes, is increasing. As a result, there is growing need for temporary residences or shelters for disaster conditions. The aim of this study was to produce post-disaster refugees housing differentiated from existing shelters using lightweight composite panels. To accomplish this, the structural performance of lightweight composite panels was validated, and an in-plane shear strength test was conducted according to the ASTM E72 criteria among the performance test methods for panels. As a result of the experiment, the maximum load for each specimen under an in-plane shear load was determined. All the experiments ended with the tear of the panel's skin section. The initial stiffness of the specimens was consistent with that predicted by the calculations. On the other hand, local crushing and tearing, as well as the characteristics of the panel, resulted in a decrease in stiffness and final failure. Specimens with an opening showed a difference in stiffness and strength from the basic experiment. The maximum load and the effective area were found to be proportional. Through this process, the allowable shear stress of the specimens was calculated and the average allowable shear stress was determined. The average ultimate shear stress of the lightweight composite panels was found to be $0.047N/mm^2$, which provides a criterion of judgement that could be used to expect the allowable load of lightweight composite panels.