• Structural Engineering and Mechanics
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• v.45 no.6
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• pp.803-819
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• 2013

This paper addresses two main issues relevant to the structural assessment of buildings subjected to explosions. The first issue regards the robustness evaluation of steel frame structures: a procedure is provided for computing "robustness curves" and it is applied to a 20-storey steel frame building, describing the residual strength of the (blast) damaged structure under different local damage levels. The second issue regards the precise evaluation of blast pressures acting on structural elements using Computational Fluid Dynamic (CFD) techniques. This last aspect is treated with particular reference to gas explosions, focusing on some critical parameters (room congestion, failure of non-structural walls and ignition point location) which influence the development of the explosion. From the analyses, it can be deduced that, at least for the examined cases, the obtained robustness curves provide a suitable tool that can be used for risk management and assessment purposes. Moreover, the variation of relevant CFD analysis outcomes (e.g., pressure) due to the variation of the analysis parameters is found to be significant.

• Journal of architectural history
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• v.19 no.6
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• pp.61-78
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• 2010

Old Russian Legation(1890) has been attracted public attention in terms of politics and foreign affairs than architectural style because of conditions of location and historical incident. Though it was heavily damaged during the Korean war, and only the tower has been restored, it is very important in architectural history in Korea, because it is the oldest western style brick building which is existing with the old bishop's house in Myeong-Dong. But it has been impossible to reveal exactly the original form as there has been few reliable materials(picture, drawing, document) and it's remains were nearly destroyed owing to development of the surroundings. Recently the decisive document(site outline map) was found, and new research on the architect Sabatine was studied. So I can get into close with the original form by the results. In this study, I tried to conjecture the original form of the old Russian legation(the size, style, plan and indoor space, arrangement of attached facilities) and I checked the location and structure of the room where King Gojong stayed when he took refuge, and the use of the passage in the basement.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.75-86
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• 2013

PURPOSES: The purpose of asphalt pavement reducing surface temperature by using Pipe cooling system is to make pleasant city life environment. METHODS: We considered building condition to lay the pipes under asphalt pavement and figured out that temperature reducing effect with pipe cooling system. In addition, we guessed rutting through wheel tracking test with a laid the pipes under asphalt mixture and performed fatigue cracking through a flexural fatigue test for performance evaluation of pipe cooling system. RESULTS: When pipe cooling system worked, the temperature of pavement model reduced quickly in test. The system can turn down the degree by 4 or 5 quickly as well. It didn't affect rutting to lay the pipes under the pavement, but it can get damaged to asphalt pavement in early stage by the result of performance evaluation. CONCLUSIONS: We figured out that pipe cooling system can turn down the temperature of aspalt pavement surface through tests. We suggest that pipe cooling system should be considered one of the effective way to solve urban heat island problem.

• 보존과학연구
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• s.23
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• pp.77-93
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• 2002

There are several methods of pest control for the prevention of wooden cultural properties from damages caused by insects, especially termites. Those are as follows; physical control, chemical control, biological control, and integrated pest management. In Korea, we primarily use mvestigation of monitoring, fumigation, treatment of insecticidal and antiseptic chemicals, soil termiticide treatment, and termite colony elimination system. As damages by termites were detected at Eunghyanggak and Saundang of Haeinsa temple in June, 1998, we carried out monitoring with wooden device, in order to investigate damages of wooden building by termite and paths of termite invasion. According to the result of investigation of monitoring from1999 to 2002, we found that termites were inhabiting continually at forests around Haeinsa and that wooden buildings such as Saundang, Cheonghwadang were damaged by termites. So we thought that control methods such as soil termiticide treatment and termite colony elimination system would be effective. Especially, to investigate efficacy of termite colony elimination system, we carried out efficacy test of termite colony elimination system in Jongmyo during 17 months(2000.7.~2001.11.). The result of efficacy test showed that termite colony elimination system eliminated termite colonies gradually(over 12 months from installation of colony elimination system to elimination of termite colony).

• Journal of the Korean Wood Science and Technology
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• v.45 no.2
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• pp.159-167
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• 2017

Historical wooden buildings in Korea are being damaged by Reticulitermes speratus kyushuensis Morimoto, a type of subterranean termite, and the scale of this damage is increasing gradually because of global warming. This study evaluated the ingestion toxicity of the phenylpyrazole insecticide fipronil to R. s. kyushuensis and its applicability as termite bait with the aim of controlling termite colonies more efficiently. An ingestion toxicity assessment was conducted and the $LT_{50}$ was determined to be 4.43 day at concentrations of 10 ppm, indicating a slow-acting effect; therefore, 10 ppm was selected as an appropriate dose. A field applicability assessment was conducted in which the number of foraging workers and the rate at which the termites fed decreased 2 weeks after baiting, and termite colony activity was no longer apparent after 4 weeks demonstrating the efficacy of fipronil at eliminating colonies. Taken together, these results, indicate that low-dose fipronil eliminated R. s. kyushuensis colonies faster than insect growth regulators; therefore, it is expected to be useful when trying to conserve historical wooden buildings.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.6
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• pp.447-456
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• 2014

In this paper, a new damage-detection method based on structural vibration is proposed. The essence of the proposed method is the detection of abrupt changes in rotation. Damage-induced rotation (DIR), which is determined from the modal flexibility of the structure, initially occurs only at a specific damaged location. Therefore, damage can be localized by evaluating abrupt changes in rotation. We conducted numerical simulations of two damage scenarios using a 10-story cantilever-type building model. Measurement noise was also considered in the simulation. We compared the sensitivity of the proposed method to localize damage to that of two conventional modal-flexibility-based damage-detection methods, i.e., uniform load surface (ULS) and ULS curvature. The proposed method was able to localize damage in both damage scenarios for cantilever structures, but the conventional methods could not.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.231-237
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• 2004

Most of the masonry buildings have many structural defects under an earthquake load due to the small tensile force and ductility. In the foreign countries there are many the reinforcing methods of masonry buildings, but the glass fiber sheet reinforcements must be used due to various conditions in Korea. The purpose of this paper is to estimate the seismic capacity of masonry buildings damaged by earthquake and reinforced by Glass Fiber Sheet. On the basis of test results, the maximum base shear force and deformation of the masonry building with GFS were remarkably increased. From the comparison by existing strength equations and test data, the new strength equation of reinforced masonry buildings with GFS was developed.

• Korean Journal of Remote Sensing
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• v.25 no.3
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• pp.271-285
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• 2009

Multi-temporal satellite imagery can be changed into a transform image that emphasizes the changed area only through the application of various change detection techniques. From the transform image, an automated change detection model calculates the optimal threshold value for classifying the changed and unchanged areas. However, the model can cause undesirable results when the histogram of the transform image is unbalanced. This is because the model uses a single threshold value in which the sign is either positive or negative and its value is constant (e.g. -1, 1), regardless of the imbalance between changed pixels. This paper proposes an advanced method that can improve accuracy by applying separate threshold values according to the increased or decreased range of the changed pixels. It applies multiple threshold values based on the cumulative producer's and user's accuracies in the automated binary change detection model, and the analyst can automatically extract more accurate optimal threshold values. Multi-temporal IKONOS satellite imagery for the Daejeon area was used to test the proposed method. A total of 16 transformation results were applied to the two study sites, and optimal threshold values were determined using accuracy assessment curves. The experiment showed that the accuracy of most transform images is improved by applying multiple threshold values. The proposed method is expected to be used in various study fields, such as detection of illegal urban building, detection of the damaged area in a disaster, etc.

• Smart Structures and Systems
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• v.16 no.1
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• pp.101-139
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• 2015

In this paper, it is aimed to investigate the restoration effect on the structural behavior of masonry arch bridges. Dandalaz masonry arch bridge located on the 4km east of Karacasu town of Aydin, Turkey is selected as a numerical example. The construction year of the bridge is not fully known, but the bridge is dated back to 15th century. Considering the current situation, it can be easily seen that the structural elements such as arch, side walls and timber blocks are heavily damaged and the bridge is unserviceable. Firstly finite element model of the bridge is constituted to reflect the current situation (before restoration) using building survey drawings. After, restoration project is explained and finite element model is reconstituted (after restoration). The structural responses of the bridge are obtained before and after restoration under dead load, live load and dynamic earthquake loads. For both conditions, maximum displacements, maximum-minimum principal stresses and maximum-minimum elastic strains are given with detail using contours diagrams and compared with each other to determine the restoration effect. From the study, it can be seen that the maximum internal forces are consisted under dynamic loads before and after restoration. Also, the restoration projects and studies have important and positive effects on the structural response of the bridge to transfer these structures to future.

• Smart Structures and Systems
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• v.7 no.5
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• pp.329-348
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• 2011

Large-scale earthquakes pose serious threats to infrastructure causing substantial damage and large residual deformations. Superelastic (SE) Shape-Memory-Alloys (SMAs) are unique alloys with the ability to undergo large deformations, but can recover its original shape upon stress removal. The purpose of this research is to exploit this characteristic of SMAs such that concrete Beam-Column Joints (BCJs) reinforced with SMA bars at the plastic hinge region experience reduced residual deformation at the end of earthquakes. Another objective is to evaluate the seismic performance of SMA Reinforced Concrete BCJs repaired with flowable Structural-Repair-Concrete (SRC). A $\frac{3}{4}$-scale BCJ reinforced with SMA rebars in the plastic-hinge zone was tested under reversed cyclic loading, and subsequently repaired and retested. The joint was selected from an RC building located in the seismic region of western Canada. It was designed and detailed according to the NBCC 2005 and CSA A23.3-04 recommendations. The behaviour under reversed cyclic loading of the original and repaired joints, their load-storey drift, and energy dissipation ability were compared. The results demonstrate that SMA-RC BCJs are able to recover nearly all of their post-yield deformation, requiring a minimum amount of repair, even after a large earthquake, proving to be smart structural elements. It was also shown that the use of SRC to repair damaged BCJs can restore its full capacity.