• Earthquakes and Structures
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• v.11 no.6
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• pp.925-942
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• 2016

With ongoing development of earthquake engineering research and the lessons learnt from a series of strong earthquakes, the seismic design concept of "resilience" has received much attention. Resilience describes the capability of a structure or a city to recover rapidly after earthquakes or other disasters. As one of the main features of urban constructions, tall buildings have greater impact on the sustainability and resilience of major cities. Therefore, it is important and timely to quantify their seismic resilience. In this work, a quantitative comparison of the seismic resilience of two tall buildings designed according to the Chinese and US seismic design codes was conducted. The prototype building, originally designed according to the US code as part of the Tall Building Initiative (TBI) Project, was redesigned in this work according to the Chinese codes under the same design conditions. Two refined nonlinear finite element (FE) models were established for both cases and their seismic responses were evaluated at different earthquake intensities, including the service level earthquake (SLE), the design-based earthquake (DBE) and the maximum considered earthquake (MCE). In addition, the collapse fragility functions of these two building models were established through incremental dynamic analysis (IDA). Based on the numerical results, the seismic resilience of both models was quantified and compared using the new-generation seismic performance assessment method proposed by FEMA P-58. The outcomes of this study indicate that the seismic resilience of the building according to the Chinese design is slightly better than that according to the US design. The conclusions drawn from this research are expected to guide further in-depth studies on improving the seismic resilience of tall buildings.

• KIEAE Journal
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• v.7 no.1
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• pp.15-22
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• 2007

Indoor air quality(IAQ) problems are not limited to large office buildings that are inadequately operated. In fact, many school buildings have significant potentials of air pollution and indoor air pollutants may be of particular concern because it is estimated that most young students who are physically weak to the pollutants spend about 90% of their time in classrooms. The goal of the study is to provide academic and architectural information on the major factors that influence indoor air quality in the elementary school. In order to gain a better understanding of IAQ problems in schools, a series of measurement studies of indoor air quality were designed and 3 different elementary school buildings located in Chuncheon were selected. The levels of CO, $CO_2$, and total volatile organic compounds(TVOCs) including formaldehyde(HCHO), major concern of this study, were measured in absence of students after class. As the results, it is noticeable that most indoor air pollution comes from sources inside the building, which are, for example, adhesives, upholstery, manufactured wood products, art and scientific supplies. The level of CO was measured similarly to that of outdoors, which means no impact on the indoor air problems since it is lower than the code. Ventilation played an important role in the level of $CO_2$ of which difference was 1.7 times in rough and 230 % of difference in the level was detected among the 3 school buildings. This concludes that indoor air problems might be result of poor building design with inadequate location of corridors within space organization or occupant activity patterns of ventilation.

• Journal of Forest and Environmental Science
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• v.33 no.4
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• pp.305-314
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• 2017

This study aimed to predict changes in forest area using a probability density function, in order to promote effective forest management in the area north of the civilian control line (known as the Minbuk area) in Korea. Time series analysis (2010 and 2016) of forest area using land cover maps and accessibility expressed by distance covariates (distance from buildings, roads, and civilian control line) was applied to a probability density function. In order to estimate the probability density function, mean and variance were calculated using three methods: area weight (AW), area rate weight (ARW), and sample area change rate weight (SRW). Forest area increases in regions with lower accessibility (i.e., greater distance) from buildings and roads, but no relationship with accessibility from the civilian control line was found. Estimation of forest area change using different distance covariates shows that SRW using distance from buildings provides the most accurate estimation, with around 0.98-fold difference from actual forest area change, and performs well in a Chi-Square test. Furthermore, estimation of forest area until 2028 using SRW and distance from buildings most closely replicates patterns of actual forest area changes, suggesting that estimation of future change could be possible using this method. The method allows investigation of the current status of land cover in the Minbuk area, as well as predictions of future changes in forest area that could be utilized in forest management planning and policymaking in the northern area.

• Structural Engineering and Mechanics
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• v.58 no.6
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• pp.1077-1085
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• 2016

In the last few years, many structural monitoring studies have been performed using different techniques to measure structures of different scales such as buildings, dams or bridges. One of the mostly used tools are GPS instruments, which have been utilized in various combinations with accelerometers and some other conventional sensors. In the current study, observation series were recorded for 8 hours with GPS receivers (NovAtel) and Inclination Measurement Sensors mounted on a television tower in Istanbul, Turkey. Each series of observations collected from two different sensors were transformed into a single coordinate system (Local Topocentric Coordinates System). The positional changes of the tower were calculated from the GPS and the inclination data. These changes were plotted in two dimensions (2D) on the same graphic. Thus, the possibility of comparison and analysis were found using the data from both the GPS and the Inclinometer complement each other, in the real test area. The positional changes of the tower were modeled for further examination. As a result, the movement of the tower within an area of $1{\times}1cm^2$ was observed. Based on the results, it can be concluded that inclinometers can be used for monitoring the structural behavior of the tower.

• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.3
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• pp.12-24
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• 1997

One argument of this study is that the policy to handle and landscape of cultural and historical property had to do with people's visual preferences. This study seeks to investigate people's visual preferences toward the landscape of cultural /historical property, specifically dealing with 'Namdaemun', which is the first class cultural property of Korea. People's visual preference was specifically examined into the four specific concepts : 'visual identity','harmony','beauty of the target property', and 'overall beauty'. Two objective variables, such as, 'distance' between the viewer and the cultural property, and 'height' of background buildings were considered possible predictors of the four visual preference variables. Photos of 'Namdaemun' were taken at three different directions and at three different distances. The photographed images of 'Namdaemun' were transferred ito the digitalized graphic images, where the height of background buildings was artificially changed and simulated. The simulated visual images were taken into the slides again. A total of 59 students of the Department of Landscape architecture at Seoul City University were sampled as subjects. A series of 17 slides were shown to the subjects four times. The subjects were asked to check their preference ratings concerning the four concepts on a 7-point Likert scale. The results found in this study were as follows : 1) In the results of ANOVA, it was clear that people visually preferred the view where the height of background buildings were lower than 15 floors to the view of more than 15 floors . 2) From the results of the path analysis, it was found that 'harmony','visual identity' and 'beauty of the target property' were direct predictors of 'the overall beauty'. The 'height ' of background buildings and the viewer's 'distance' were not found to be direct predictors, however, they demonstrated their effects on 'the overall beauty' through the other variable, which were direct predictors of 'the overall beauty'. In sum, the longer the distance and the higher the background buildings, the lower people's preference with the 'overall beauty'. These indirect paths, in turn, also explain why and how the 'height' of background buildings and the viewer's 'distance' negatively influence the 'overall beauty'. An implication from the these results is that when the height of background buildings were not controllable, there would be some other strategies for improving people's visual preference toward the historical /cultural view. To increase 'visual identity' of the cultural property, for example, changing colors of the cultural property or increasing the lighting level, etc., would be one strategy, since the increased 'visual identity' will, in turn, increase 'the overall beauty'.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.8
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• pp.852-858
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• 2005

Modeling techniques for air quality are useful tools in air quality management. Especially, the air quality in urban area is significantly influenced by local surroundings such as buildings and traffic. When considering the air quality in a street canyon, which is usually filmed by a series of consecutive buildings and a street, currently available air dispersion model have a number of limitations to predict the air quality properly. In this study, it is aimed to propose an empirical model for the air quality in urban street canyons. A series of wind tunnel tests, followed by statistical analysis, were conducted. In conclusion, it is found that a wide street canyon and a perpendicular external wind to the street canyon are beneficial to achieve an enhanced air quality in street canyon environment. The model prediction using the proposed model also shows reliable correlations to the wind tunnel test results.

• Journal of architectural history
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• v.7 no.4 s.17
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• pp.131-150
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• 1998

Main theme of this study is the acceptance phase of western architectural culture in modern east-north asia through a series of actual survey and typological analysis of existing church buildings in modern Korea. China. Japan. For this study, 126 modern church buildings of Korea, China, Japan are selected. Also, main subject of this study has deal with the side of culture - thought which background of christianity acceptance and acceptance mind of acceptance main-body, culture adaptation and transformation based on characteristic culturalization of Korea, China, Japan. Especially, I would consistently tried to see the acceptance phase of western architectural culture according to differential acceptance mind of acceptance main-body based on characteristic culturalization of three countries. Conclusively, in the point of view of western architectural culture acceptance phase, it could be said that Korean church architecture had characterized as a blending phase of the two eclectic architectural culture. And in the case of china, as a coexistance phase of the two architectural culture with more western style-oriented. On the other hand, Japanese church architecture had characterized as a syncretism phase of the both traditional and western architectural culture, though it is eclectic style-oriented. Therefore, it is thought that different acceptance mind of western culture had main factors caused of differential acceptance phase, when the two architectural culture, the traditional and the western, encounters.

• Smart Structures and Systems
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• v.16 no.4
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• pp.725-742
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• 2015

Tuned mass dampers (TMD) are devices employed in vibration control since the beginning of the twentieth century. However, their implementation for controlling the seismic response in civil structures is more recent. While the efficiency of TMD on structures under far-field earthquakes has been demonstrated, the convenience of its employment against near-fault earthquakes is still under discussion. In this context, the study of this type of device is raised, not as an alternative to the seismic isolation, which is clearly a better choice for new buildings, but rather as an improvement in the structural safety of existing buildings. Seismic records with an impulsive character have been registered in the vicinity of faults that cause seismic events. In this paper, the ability of TMD to control the response of structures that experience inelastic deformations and eventually reach collapse subject to the action of such earthquakes is studied. The results of a series of nonlinear dynamic analyses are presented. These analyses are performed on a numerical model of a structure under the action of near-fault earthquakes. The structure analyzed in this study is a steel frame which behaves as a single degree of freedom (SDOF) system. TMD with different mass values are added on the numerical model of the structure, and the TMD performance is evaluated by comparing the response of the structure with and without the control device.

• Structural Engineering and Mechanics
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• v.30 no.2
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• pp.211-223
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• 2008

A number of studies have suggested that the use of high ductile and high shear materials, such as Engineered Cementitious Composites (ECC) and High Performance Fiber Reinforced Cementitious Composites (HPFRCC), significantly enhances the shear capacity of structural elements, even with/without shear reinforcements. The present study emphasizes the development of a nonlinear model of shear behaviour of a HPFRCC panel for application to the seismic retrofit of reinforced concrete buildings. To model the shear behaviour of HPFRCC panels, the original Modified Compression Field Theory (MCFT) for conventional reinforced concrete panels has been newly revised for reinforced HPFRCC panels, and is referred to here as the HPFRCC-MCFT model. A series of experiments was conducted to assess the shear behaviour of HPFRCC panels subjected to pure shear, and the proposed shear model has been verified through an experiment involving panel elements under pure shear. The proposed shear model of a HPFRCC panel has been applied to the prediction of seismic retrofitted reinforced concrete buildings with in-filled HPFRCC panels. In retrofitted structures, the in-filled HPFRCC element is regarded as a shear spring element of a low-rise shear wall ignoring the flexural response, and reinforced concrete elements for beam or beam-column member are modelled by a finite plastic hinge zone model. An experimental study of reinforced concrete frames with in-filled HPFRCC panels was also carried out and the analysis model was verified with correlation studies of experimental results.

• Structural Engineering and Mechanics
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• v.53 no.2
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• pp.189-204
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• 2015

After the large destruction of Lisbon due to the 1755 earthquake, the city had to be almost completely rebuilt. In this context, an innovative structural solution was implemented in new buildings, comprising internal timber framed walls which, together with the floors timber elements, constituted a 3-D framing system, known as "cage", providing resistance and deformation capacity for seismic loading. The internal timber framed masonry walls, in elevated floors, are constituted by a timber frame with vertical and horizontal elements, braced with diagonal elements, known as Saint Andrew's crosses, with masonry infill. This paper describes an experimental campaign to assess the in-plane cyclic behaviour of those so called "frontal" walls. A total series of 4 tests were conducted in 4 real size walls. Two models consist of the simple timber frames without masonry infill, and the other two specimens have identical timber frames but present masonry infill. Experimental characterization of the in-plane behaviour was carried out by static cyclic shear testing with controlled displacements. The loading protocol used was the CUREE for ordinary ground motions. The hysteretic behaviour main parameters of such walls subjected to cyclic loading were computed namely the initial stiffness, ductility and energy dissipation capacity.