• Hwankyungkyoyuk
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• v.24 no.3
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• pp.18-25
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• 2011

This study was conducted to evaluate the effects of volatile organic compounds and formaldehyde of newly-built school classroom indoor air on the neurobehavioral functions of students. The elementary schools that were opened in September 2008(as of September 2008) was selected for newly-built school and the elementary school that were opened in March 2006 was selected for control group schools. The concentration of formaldehyde(HCHO), a hazardous organic compound that exists in the air of classrooms, exceeded the standard value of $108.2{\mu}g/m^3$ in newly-built schools while it was $60.8{\mu}g/m^3$ in control group schools, which is around 60% of the standard concentration. However, the concentration of the total volatile organic compounds(TVOCs) was $788.9{\mu}g/m^3$ and $756.1{\mu}g/m^3$ in newly-built schools and control group schools respectively, which are approximately two times higher than the standard concentration. In newly-built schools, the mean reaction time of additions and symbol digit, respectively 3,020ms and 2,398ms in pre-exposure were increased to 3,167ms and 2,514ms respectively in post-exposure. The difference of mean reaction time between pre and post exposure was 146.8 ms, or 4.6%, and 116.7ms, or 4.8%, respectively, showing statistically-significant increase of reaction time(p<0.05). On the contrary, the difference of reaction time of both tests were not statistically significant in the control group schools. These results showed that the neurobehavioral performance of newly-built schools students were affected by volatile organic compounds and formaldehyde of classroom indoor air.

• Steel and Composite Structures
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• v.34 no.3
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• pp.377-391
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• 2020

A concrete filled steel tube (CFT) column with stiffeners has preferable behavior subjected to axial loading condition due to delay local buckling of the steel wall than traditional CFT columns without stiffeners. Welding lines in welded built-up steel box columns is expected to behave as longitudinal stiffeners. This study has presented a numerical investigation into the behavior of built-up concrete filled steel tube columns under axial pressure. At first stage, a finite element model (FE) has been built to simulate the behavior of built-up CFT columns. Comparing the results of FE and test has shown that numerical model passes the desired conditions and could accurately predict the axial performance of CFT column. Also, by the raise of steel tube thickness, the load bearing capacity of columns has been increased due to higher confinement effect. Also, the raise of concrete strength with greater cross section is led to a higher load bearing capacity compared to the steel tube thickness increment. In CFT columns with greater cross section, concrete strength has a higher influence on load bearing capacity which is noticeable in columns with more welding lines.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.1178-1178
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• 2005

• Steel and Composite Structures
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• v.42 no.1
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• pp.1-22
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• 2022

In cold-formed steel (CFS) structures, such as trusses, transmission towers and portal frames, the use of back-to-back built-up CFS unequal angle sections are becoming increasingly popular. In such an arrangement, intermediate welds or screw fasteners are required at discrete points along the length, preventing the angle sections from buckling independently. Limited research is available in the literature on axial strength of back-to-back built-up CFS unequal angle sections. The issue is addressed herein. This paper presents an experimental investigation reported by the authors on back-to-back built-up CFS unequal angle sections with intermediate stiffeners under axial compression. The load-axial shortening behaviour along with the deformed shapes at failure are reported. A nonlinear finite element (FE) model was then developed, which includes material non-linearity, geometric imperfections and modelling of intermediate fasteners. The FE model was validated against the experimental test results, which showed good agreement, both in terms of failure loads and deformed shapes at failure. The validated finite element model was then used for the purpose of a parametric study comprising 96 models to investigate the effect of longer to shorter leg ratios, stiffener provided in the longer leg, thicknesses and lengths on axial strength of back-to-back built-up CFS unequal angle sections. Four different thicknesses and seven different lengths (stub to slender columns) with three overall widths to the overall depth (B/D) ratios were investigated in the parametric study. Axial strengths obtained from the experimental tests and FE analyses were used to assess the performance of the current design guidelines as per the Direct Strength Method (DSM); obtained comparisons show that the current DSM is conservative by only 7% and 5% on average, while predicting the axial strengths of back-to-back built-up CFS unequal angle sections with and without the stiffener, respectively.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.230-233
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• 2003

As the consumer's consumption standard has raised, occupants' needs for the apartment is diversified and complicated. But the existing mass housing supply method has many problems and it couldn't satisfy the dwellers' various needs and overall expected life span. In order to correspond those needs, construction firms have introduced several method, such as plus option, minus option, on-time option, change up service and so on. The custom-built apartment is more supplementary and it can reflect the consumer's needs to the apartment directly. But after running the custom-built apartment, several problems is revealed. So. in this study, I defined the general idea of the custom-built apartment and then collect the case of the custom-built apartment.

• Journal of architectural history
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• v.25 no.4
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• pp.57-64
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• 2016

It was believed that Jeongnimsa temple was built after the capital was moved from Gongju to Buyeo. It was confirmed that it was built A.D. $625{\pm}20$ by conducting a paleomagnetic analysis on the fireplace, which was recently found at the bottom of Jungmunji(middle gate). Consequently, it is assumed that the temple was built in the early 7th century unlike the previous point of view. Therefore, this study evaluated if the fireplace at the bottom of Jungmunji was found at the geological stratum representing the Jeongnimsa temple. Moreover, the study examined when the fireplace at the bottom of Jungmunji was constructed on the soil stratum. It is possible that the fireplace was built in the early 7th century as shown in the paleomagnetic analysis. However, when we compared the soil strata of the Jungmunji and the existing five-story stone pagoda, it showed that the ground was prepared differently and they were built over a fairly long period of time. Furthermore, I discovered that there was a wooden pagoda under the five-story stone pagoda by examining the soil strata map. Therefore, previous studies evaluated the arrangement of auxiliary buildings of Jeongnimsa temple and concluded that it was built in the early 7th century. It is hard to determine when the temple was built based on the arrangement of auxiliary buildings, because it takes a long time to build a temple and auxiliary buildings can be relocated during this long construction period. Rather, we have to admit that there are various arrangement patterns through minor changes in buildings from the one pagoda and one main building(Geumdang) arrangement.

• Steel and Composite Structures
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• v.33 no.4
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• pp.595-614
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• 2019

In cold-formed steel (CFS) structures, such as trusses, transmission towers and portal frames, the use of back-to-back built-up CFS unequal angle sections are becoming increasingly popular. In such an arrangement, intermediate welds or screw fasteners are required at discrete points along the length, preventing the angle sections from buckling independently. Limited research is available in the literature on axial strength of back-to-back built-up CFS unequal angle sections. The issue is addressed herein. This paper presents an experimental investigation on both the welded and screw fastened back-to-back built-up CFS unequal angle sections under axial compression. The load-axial shortening and the load verses lateral displacement behaviour along with the deformed shapes at failure are reported. A nonlinear finite element (FE) model was then developed, which includes material non-linearity, geometric imperfections and modelling of intermediate fasteners. The FE model was validated against the experimental test results, which showed good agreement, both in terms of failure loads and deformed shapes at failure. The validated FE model was then used for the purpose of a parametric study to investigate the effect of different thicknesses, lengths and, yield stresses of steel on axial strength of back-to-back built-up CFS unequal angle sections. Five different thicknesses and seven different lengths (stub to slender columns) with two different yield stresses were investigated in the parametric study. Axial strengths obtained from the experimental tests and FE analyses were used to assess the performance of the current design guidelines as per the Direct Strength Method (DSM); obtained comparisons show that the current DSM is conservative by only 7% on average, while predicting the axial strengths of back-to-back built-up CFS unequal angle sections.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1244-1249
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• 2006

Because students are spending more time in their classroom for learning and study, indoor air quality problems in school classrooms are very important. when the classroom is built for the first time, namely newly built school, the selection of inside finishing material is directly connected with indoor air quality problems especially with HCHO and TVOC. But until now, there is no plenty of study about this. Moreover, there are some concerns about the desks and chairs which are used in classroom will affect the air quality. but almost no study is being made at all Therefore, this study focuses on the field survey and analysis of classroom indoor air quality in newly built schools in Changwon. In this study filed surveys and analysis are conducted as follows. 1) The effect of the material difference in general classroom. 2) The effect of the material and loading ratio difference in special classroom. 3) The effect of the desks and chairs in general classroom.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.807-810
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• 1998

This paper presents BIST (Built-in self-test) techniques for detection of path delay faults in digital circuits. In the proosed BIST schemes, the shift registers make possible to concurrently generate and compact the latched test data. Therefore the test time is reduced efficiently. By reordering the elements of th shifte register based on the information of the hamming distance of each memory elements in CUt, it is possible to increase the number of path delay faults detected robustly/non-robustly. Experimental results for ISCAS'89 benchmark circuits show the efficiency of the proposed BIST techniques.

• Advances in Computational Design
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• v.5 no.2
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• pp.127-146
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• 2020

Building Information Modeling (BIM) is increasingly used throughout the facility's life cycle for various applications, such as design, construction, facility management, and maintenance. For existing buildings, the geometry of as-built BIM is often constructed using dense, three dimensional (3D) point clouds data obtained with laser scanners. Traditionally, as-built BIM systems do not contain the material and textural information of the buildings' elements. This paper presents a semi-automatic method for generation of material and texture rich as-built BIM. The method captures and integrates material and textural information of building elements into as-built BIM using thermal infrared sensing (TIS). The proposed method uses TIS to capture thermal images of the interior walls of an existing building. These images are then processed to extract the interior walls using a segmentation algorithm. The digital numbers in the resulted images are then transformed into radiance values that represent the emitted thermal infrared radiation. Machine learning techniques are then applied to build a correlation between the radiance values and the material type in each image. The radiance values were used to extract textural information from the images. The extracted textural and material information are then robustly integrated into the as-built BIM providing the data needed for the assessment of building conditions in general including energy efficiency, among others.