• Asian Journal for Public Opinion Research
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• v.9 no.2
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• pp.188-211
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• 2021

Decreasing response rates to traditional survey methods, like face-to-face and telephone interviews, have led survey practitioners around the world to seek new ways of conducting surveys in recent years." The COVID-19 pandemic exacerbated this problem because it made conducting face-to-face interviews even more difficult than before. For example, it made conducting face-to-face surveys infeasible in 2020 in South Korea, and so the Korean Academic Multimode Open Survey (KAMOS) was unable to conduct a planned face-to-face survey to recruit new panel members. The entire 8,514-member panel, established via two-stage probability-based sampling from 2016 to 2019, was invited to take three online/telephone surveys in 2020. Of these panel members, 1,352 responded to at least one survey in 2020. To test to what extent the panel remained representative of the adult South Korean population, we compared the two groups of panel members: those who responded to at least one survey in 2020 and those who did not. After weighting both groups on the basis of age, sex, and geographical area, we analyzed their responses to some of the questions that were asked during multiple rounds of the face-to-face panel-recruiting interviews. Using Cohen's d for survey items that could be analyzed numerically and Cramér's V for categorical items, we were able to conclude that the respondents to the 2020 surveys were equivalent to the non-respondents in terms of both demographics and in the answers they originally gave to substantive questions on a variety of topics related to social science or public opinion research, including questions about quality of life, societal issue, and politics (Cohen's d items <0.2, 95% CI; Cramér's V items <0.1, 95% CI). This analysis may provide a model for others who wish to test the continued representativeness of their panel or who would like to use a different survey mode or change some other aspect of their methodology and test whether it is equivalent to their former methodology. Our success in building a panel that retained its representativeness may be useful to those in other countries where face-to-face surveys had previously been the norm but are becoming increasingly difficult to conduct.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.49-52
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• 2008

The design strength of panel zones, which was based on Krawinkler model, was investigated by comparing it with existing test and FEM results. The design strength overestimates of the strength of panel zones with thick column flange while it matches well with the strength of panel zones with thin column flange. More extensive studies are needed to develop a mathematical model which can properly define the inelastic behavior of panel zones with various column flange thicknesses and to determine a more rational design strength.

• Advances in concrete construction
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• v.13 no.2
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• pp.153-162
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• 2022

Prefabricated exterior wall panel is the main non-load-bearing component of assembly building, which affects the comprehensive performance of thermal insulation and durability of the building. It is of great significance to develop new prefabricated exterior wall panel with durable and lightweight characteristics for the development of energy-saving and assembly building. In the prefabricated sandwich insulation hanging wall panel, the selection of material for the outer layer and the arrangement of the connector of the inner and outer wall layers affect the mechanical performance and durability of the wall panels. In this paper, high performance cement-based composites (HPFRC) are used in the outer layer of the new type wall panel. FRP bars are used as the interface connector. Through experiments and analysis, the influence of the arrangement of connectors on the mechanical behaviors of thin-walled composite wall panel and the panel with window openings under two working conditions are investigated. The failure modes and the role of connectors of thin-walled composite wallboard are analyzed. The influence of the thickness of the wall layer and their combination on the strain growth of the control section, the initial crack resistance, the ultimate bearing capacity and the deformation of the wall panels are analyzed. The research work provides a technical reference for the engineering design of the light-weight thin-walled and durable composite sandwich wall panel.

• Journal of the Korean Wood Science and Technology
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• v.29 no.3
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• pp.36-46
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• 2001

This study was to find a way of reusing wood and plastic wastes, which considered as a troublesome problem to be solved in this age of mass production and consumption, in manufacturing wood fiber-polypropylene fiber composite panel. And the feasibility of this composite panel as a substitute for existing headliner base panel of automobile was also discussed, especially based on physical and mechanical performance. Nonwoven web composite panels were made from wood fiber and polypropylene fiber formulations of 50 : 50, 60 : 40, and 70 : 30, based on oven-dry weight, with densities of 0.4, 0.5, 0.6, and 0.7 g/$cm^3$. At the same density levels, control fiberboards were also manufactured for performance comparison with the composite panels. Their physical and mechanical properties were tested according to ASTM D 1037-93. To elucidate thickness swelling mechanism of composite panel through the observation of morphological change of internal structures, the specimens before and after thickness swelling test by 24-hour immersion in water were used in scanning electron microscopy. Test results in this study showed that nonwoven web composite panel from wood fibers and polypropylene fibers had superior physical and mechanical properties to control fiberboard. In the physical properties of composite panel, dimensional stability improved as the content of polypropylene fiber increased, and the formulation of wood fiber and polypropylene fiber was considered to be a significant factor in the physical properties. Water absorption decreased but thickness swelling slightly increased with the increase of panel density. In the mechanical properties of composite panel, the bending modulus of rupture (MOR) and modulus of elasticity (MOE) appeared to improve with the increase of panel density under all the tested conditions of dry, heated, and wet. The formulation of wood fiber and polypropylene fiber was considered not to be a significant factor in the mechanical properties. All the bending MOR values under the dry, heated, and wet conditions met the requirements in the existing headliner base panel of resin felt.

• Computers and Concrete
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• v.14 no.6
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• pp.767-783
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• 2014

The use of composite materials to strengthen reinforced concrete (RC) structures against blast terror has great interests from engineering experts in structural retrofitting. The composite materials used in this study are rigid polyurethane foam (RPF) and aluminum foam (ALF). The aim of this study is to use the RPF and the ALF to strengthen the RC panels under blast load. The RC panel is considered to study the RPF and the ALF as structural retrofitting. Field blast test is conducted. The finite element analysis (FEA) is also used to model the RC panel under shock wave. The RC panel performance is studied based on detonating different TNT explosive charges. There is a good agreement between the results obtained by both the field blast test and the proposed numerical model. The composite materials improve the RC panel performance under the blast wave propagation.

• Fire Science and Engineering
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• v.23 no.2
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• pp.20-26
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• 2009

Reaction-to-Fire's performances such as combustion properties of sandwich panels were tested according to ISO 13784-1 (room corner test for sandwich panel building systems) method which is made for the purpose of supplementing ISO 9705 room corner test, and analyzed comparatively. Several variables including heat release rate, smoke production rate, FIGRA, SMOGRA, thermal configuration, visual check lists and so on, were analyzed for specific four materials on sandwich panel systems. Finally, Reaction-to-Fire's performances of test results on each material by ISO 13784-1 are categorized by applying to the classification systems of both EN 13501-1 and Eurefic Research Program.

• Proceedings of the Safety Management and Science Conference
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• 2009.04a
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• pp.523-529
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• 2009

The ACF(Anisotropic Conductive Film) is used for bonding Drive IC and OLED display device panel. If ACF bonding process is problem, a malfunction of line defect can occur. Because electric resistance increase between the panel and drive IC after a period of time, drive IC can not supply enough current to the panel. This paper is studied on a method of test for line defect.

• Journal of the Korean Statistical Society
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• v.28 no.4
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• pp.489-501
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• 1999

In this paper, we consider the panel data regression model in which the disturbances have nested error component. We derive a Lagrange Multiplier(LM) test which is jointly testing for the presence of random individual effects and nested effects under the normality assumption of the disturbances. This test extends the earlier work of Breusch and Pagan(1980) and Baltagi and Li(1991). Further, it is shown that this LM test has the same asymptotic distribution without normality assumption of the disturbances.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.577-584
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• 2003

Tension tests of half-thickness concrete containment wall elements and material tests were conducted to derive a crack pattern and constitutive law of concrete. Main test variables are reinforcement ratio and the applied load ratio in two direction, and its effect on the behavior of reinforced concrete panel subjected to biaxial tension is investigated. Based on the test results, analytical expression is derived for the stress-strain relationship of concrete in tension. Ultimate analyses of reinforced concrete panels are carried out by a general purpose structural analysis computer program(ABAQUS), and its results are compared with the test results. The present analysis focuses on the effects of pre-analysis prior to test of specimens. These ultimate tensile analyses as pre-analysis are essential and important to design an effectual scheme of test.

• Journal of the Korea Institute of Building Construction
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• v.1 no.1
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• pp.135-142
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• 2001

This study is for the investigation of form using the aluminum-compound metal frame(Aluminum frame reinforced panel : AFR panel) which is improved in the capacity in the wall-concrete structure in steal of using the existing form which has problems such as, excessive exposure of cement, the loss of labor when it is constructed or disjointed, and it's economical efficiency compared with that of EURO Form. AFR panel passes the KS F 8006 test, and as a result of field test, it's displacement is satisfied with Specification. And using AFR panel is more economical than that of EURO Form because saving labor cost which plays a major part in cost saving in formwork is more effective in retrenching total cost than increment of material cost.