• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.308-311
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• 2004

It is reported that there is a limit in increasing heavy-weight impact noise isolation performance of the load bearing wall system apartments to meet the regulation of the Ministry of Construction and Transportation (MOCT). To increase the heavy-weight impact noise isolation performance, improvement in structural systems such as increasing concrete slab thickness and application of rahmen structure were proposed. In this study floor impact sound levels from toil apartments with two rahmen structure multi-story residential buildings were measured before the construction of the buildings finished. Measurements were made at living room and two bedrooms at each apartment when the finishing processes were finished. The average value of light-weight impact sound level from ten apartments was 56dB (L'$\sub$n,Aw/). The heavy-weight impact sound level was 44dB (L'$\sub$i.Fmax.Aw/) and the impact sound level of the impact ball was 41dB(L'$\sub$i.Fmax.Aw/), As a result floor impact noises at the rahmen structure system were lower than the regulation level.

• 산업기술연구
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• 제26권B호
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• pp.111-118
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• 2006

The reinforced concrete structure is one of the most popular structures in real construction. Concrete has been strengtened rapidly due to the development of new material and construction technology. But as the concrete has been getting stronger, the brittleness of material has increased and the better ductility has been required. So, the study for strengthening stiffener has been urgently needed. As we said above, it is expected that the use of high strength steel and concrete will be increased. However, The experimental data is not enough for solving problems of the use of high strengthened steel and concrete. In this research, we analyzed 45 combinations of the strength levels of concrete, the thickness of material and the steel strength with regard to simple Reinforced Concrete SLAB Beam bridge. The program MIDAS CIVIL was used to find the optimal combination. As a result, it was found that strength ratio per unit section is in inverse proportion to the strength of material and that the strengths of steel are respectively 400 MPa for low strengthened concrete and 300 MPa for high strengthened concrete. For economic aspect and usability, the effect of high strength steel is not as high as we expected it would be.

• 한국초전도ㆍ저온공학회논문지
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• 제22권1호
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• pp.1-6
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• 2020

This is a parameter study for the direct fabrication of a large grain YBCO bulk superconductors using Y₂O₃, BaCO₃ and CuO powders without any grinding step. The cracks, which have been formed due to volume contraction during calcination step, have been prevented by controlling the heating rate at 930~950 ℃. It has been observed that multi-grain growth has occurred due to the dissolution of Sm123 seed due to the retention of carbon in Ba-Cu-O melt. In order to accelerate the carbon release in prior calcination heat treatment, the reduction of pellet thickness and the drilling of artificial holes have been applied. Single-grain YBCO bulk superconductor has been successfully fabricated by stacking multiple thin slab. However, the crack formation has been rather prominent for the compact with artificial holes. The use of buffer pellet, which is supposed to act as diffusion barrier, has prevented the dissolution of Sm123 seed crystal and has led to the growth of single grain of high content of carbon containing specimen.

• Steel and Composite Structures
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• 제37권1호
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• pp.1-14
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• 2020

Composite beams with corrugated steel webs represent a new innovative system which has emerged in the past decade for medium span in the construction technology. The use of composite beams with corrugated steel webs results in a range of benefits, including flexible spaces and reduced foundation costs in the construction technology. The thin corrugated web affords a significant weight reduction of these beams, compared with hot-rolled or welded ones. In the current research, an optimal designed I-girder beam with corrugated web has been proposed to improve the structural performance of continuous composite girder under bending moment. The experimental program has been conducted for six simply supported composite beams with different loading conditions. The tested specimens are designed by using one of the stochastic techniques called hunting search algorithm. In the optimization process, besides the thickness of concrete slab and studs, corrugated web properties are considered as design variables. The design constraints are respectively implemented from Eurocode 3, BS-8110 and DIN 18-800 Teil-1. The last part of the study focuses on performing a numerical study on composite beams by utilizing finite element analysis and the bending behavior of steel girders with corrugated webs experimentally and numerically verified the results. A nonlinear analysis was carried out using the finite element software ANSYS on the composite beams which were modelled using the elements ten-node high order quadrilateral type.

• KIEAE Journal
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• 제13권1호
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• pp.29-37
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• 2013

This study intended to introduce the method of designing an eco-friendly building based on BIM(Building Information Modeling) and BIM-based application. The proposed application aimed to generate the environmental performance of the designed alternative automatically in real-time manner in the process of architectural design. We focused on the feasibility of BIM-based eco-friendly design process and the applicability of the developed application for the architectural design practice. In this manner, in the end of paper, we proposed the so-call EcoBIM which is the performance evaluation module for the designed alternative using BIM in the real-time manner and the new design process with it. EcoBIM generate the coefficient of overall heat transmission of wall, roof and slab of the designed alternative with their physical characteristics such as thickness, thermal resistance and so on.

• Steel and Composite Structures
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• 제19권6호
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• pp.1381-1402
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• 2015

The application of composite steel-concrete slabs with profiled steel sheeting has increased, due to the various advantages in relation to reinforced concrete slabs such as, the reduced thickness, the reduced amount of lost formwork needed, as well as the speed of execution. The loss of longitudinal shear resistance is, generally, the governing design mode for simply supported spans of common lengths. For common distributed loadings, the composite behaviour is influenced by the partial shear connection between the concrete and the steel sheeting. The present research work is intended to contribute to improving the ultimate limit state behaviour of composite slabs using end anchorage. Eurocode 4, Part 1.1 (EN 1994-1-1) provides an analytical methodology for predicting the increase of longitudinal resistance, achieved by using shear studs welded through the steel sheeting as the end anchorage mechanism. The code does not supply an analytical methodology for other kinds of end anchorage so, additional tests or studies are needed to prove the effectiveness of these types of anchorage. The influence of end anchorage mechanisms provided by transverse rebars at the ends of simply supported composite slabs is analysed in this paper. Two experimental programmes were carried out, the first to determine the resistance provided by the new end anchorage mechanism and the second to analyse its influence on the behaviour of simply supported composite slabs.

• Structural Engineering and Mechanics
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• 제34권5호
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• pp.635-662
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• 2010

In this study, the effect of superstructure-abutment continuity on the distribution of live load effects among the girders of integral abutment bridges (IABs) is investigated. For this purpose, two and three dimensional finite element models of several single-span, symmetrical integral abutment and simply supported (jointed) bridges (SSBs) are built and analyzed. In the analyses, the effect of various superstructure properties such as span length, number of design lanes, girder size and spacing as well as slab thickness are considered. The results from the analyses of two and three dimensional finite element models are then used to calculate the live load distribution factors (LLDFs) for the girders of IABs and SSBs as a function of the above mentioned parameters. LLDFs for the girders are also calculated using the AASHTO formulae developed for SSBs. Comparison of the analyses results revealed that the superstructure-abutment continuity in IABs produces a better distribution of live load effects among the girders compared to SSBs. The continuity effects become more predominant for short span IABs. Furthermore, AASHTO live load distribution formulae developed for SSBs lead to conservative estimates of live load girder moments and shears for short-span IABs.

• 한국광학회지
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• 제10권3호
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• pp.208-213
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• 1999

반도체 및 박막의 두께 측정에 많이 이용되는 분광 타원해석기의 입사각을 정밀하게 보정하기 위한 방법을 제안하고 이를 실험적으로 확인하였다. 몇 종류의 광학유리를 이용하여 프리즘과 기판을 가공하였다. 프리즘의 꼭지각과 최소 벗어나 기각을 측정해 광학유리의 굴절률을 결정하였고 브루스터각(Brewster's angle)에서 측정한 유리기판의 타원해석 스펙트럼을 분석하기 위한 기준값으로 이 굴절률을 사용하여 분광 타원해석기의 입사각을 0.01도의 정밀도로 결정,보정하였다.

• 한국철도학회논문집
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• 제7권4호
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• pp.312-318
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• 2004

The wall in a subway structure is easily subject to crack occurrence since its expansion and shrinkage associated with hydration heat reaction is constrained by the slab. The greater problem is that the crack in the wall may be developed to pass through thickness and eventually deteriorate the structure due to rusting of reinforced steel. Thus, this study aims at controlling thermal cracks as much as possible and determining an optimized size of concrete placement through hydration heat analysis. For this study, effects of placement height, length, temperature and types of cement on the thermal cracks were evaluated by temperature rise, thermal stress and crack index. As results of parametric study, it was found that placement height and length do not have an effect on the temperature rise but have significant one on thermal stress which relates to direct possibility of thermal crack occurrence. This means that proper selection of size balancing internal constraint with external one is much more important than reducing the placement height and length simply. In order to prevent from thermal cracks most effectively, in addition, it was noted to reduce placement temperature and to use the cement blended with mineral admixture.

• 한국안전학회지
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• 제31권3호
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• pp.89-95
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• 2016

Lately, the high-strength concrete is often used to increase the lifespan of bridges. The benefits of using the high-strength concrete are that it increases the durability and strength. On the contrary, it reduces the cross-section of the bridges. This study conducted structural performance tests of the bridge deck slabs applying high-strength concrete. As result of the tests, specimens of bridge deck slabs were destroyed through punching shear. Moreover, the tests exposed that the high-strength concrete bridge deck slabs satisfy the flexural strength and the punching shear strength at ultimate limit state(ULS). Also, limiting deflection of the concrete fulfilled serviceability limit state(SLS) criteria. These results indicated that the bridge deck slabs designed by high-strength concrete were enough to secure the safety factor despite of its low thickness.