• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.107-114
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• 2019

In this paper, the P-wave multiple detection system for the fast and accurate earthquake early warning nearby the epicenter was developed. The developed systems were installed in five selected public buildings for the validation. During the monitoring, a magnitude 2.3 earthquake occurred in Pohang on 26 September 2019. P-wave initial detection algorithms were operated in three out of four systems installed in Pohang area and recorded as seismic events. At the nearest station, 5.5 km from the epicenter, P-wave signal was detected 1.2 seconds after the earthquake, and S-wave was reached 1.02 seconds after the P-wave reached, providing some alarm time. The maximum accelerations recorded in three different stations were 6.28 gal, 6.1 gal, and 5.3 gal, respectively. The alarm algorithm did not work, due to the high threshold of the maximum ground acceleration (25.1 gal) to operate it. If continuous monitoring and analysis are to be carried out in the future, the developed system could use a highly effective earthquake warning system suitable for the domestic situation.

• International Journal of High-Rise Buildings
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• v.6 no.3
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• pp.227-235
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• 2017

This paper describes some of the challenges for structural design of a mid-story seismic isolated high-rise building, which is located near Tokyo station, completed in 2015. The building is a mixed-use complex and encompasses three volumes: one substructure including basement and lower floors, and a pair of seismic isolated superstructures on the substructure. One is a 136.5m high Main Tower (office use), and the other is a 98.5 m high South Tower (hotel use). The seismic isolation systems are arranged in the $3^{rd}$ floor of the Main Tower and $5^{th}$ floor of the South Tower, so that we call this isolation system as the mid-story seismic isolation. The primary goal of the structural design of this building was to secure high seismic safety against the largest earthquake expected in Tokyo. We adopted optimal seismic isolation equipment simulated by dynamic analysis to minimize building damage. On the other hand, wind-induced vibration of a seismic isolated high-rise building tends to be excited. To reduce the vibration, the following strategies were adopted respectively. In the Main Tower with a large wind receiving area, we adopted a mechanism that locks oil dampers at the isolation level during strong wind. In the South Tower, two tuned mass dampers (TMDs) are installed at the top of the building to control the vibration. In addition, our paper will also report the building performance evaluated for wind and seismic observation after completion of the building. In 2016, an earthquake of seismic intensity 3 (JMA scale) occurred twice in Tokyo. The acceleration reduction rate of the seismic isolation level due to these earthquakes was approximately 30 to 60%. These are also verified by dynamic analysis using observed acceleration data. Also, in April 2016, a strong wind exceeding the speed of 25m/s occurred in Tokyo. On the basis of the record at the strong wind, we confirmed that the locking mechanism of oil damper worked as designed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5191-5198
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• 2010

Although numerous studies have analyzed the relationship between subway travel demand (STD) and various characteristics of subway catchment area (SCA), a few studies examined the relationship between STD and the structure of pedestrian networks within each SCA. Hence, this study evaluates the structure of pedestrian networks within 79 SCAs in the city of Busan using Space syntax and investigates the relationship between STD and several characteristics of SCA including the spatial structure of pedestrian network. The analysis results show that the spatial integration of pedestrian networks within the SCAs, which represents the magnitudes of walking accessibility to subway station, is positively associated with STD among the three spatial indexes such as integration, connectivity, and intelligibility. In addition, the results show that STD significantly increases as the number of travel gathering facilities and the average floor area ratio within the SCAs increase. This study ultimately corroborates that designing the grid pedestrian network and assigning the travel gathering facilities to the compact buildings within SCAs are needed to ameliorate the spatial structure of SCA in the city of Busan as transit-oriented development system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5165-5176
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• 2010

This study is an attempt to seek ways to revitalize the main streets in local city with regard to urban regeneration. It focuses on the case of Myeong-dong Fashion Street located in front of Cheonan Station, which recently lost its vitality. In order to explore causes of the decline and solutions for restore, this paper investigate the concerned urban area by approaching through three different aspects: physical and environmental aspects, social and economic aspects, historic and cultural aspects. In addition, the street visitors were surveyed on their visiting patterns, priorities and discontents about the components of street, and preferences for its restoring, etc. The investigation resulted in following findings and proposals. In physical and environmental dimension, it is needed to create legal incentives for encouraging local residents to develop their own district, and suggested to plan green space for relaxation and cultural arts space by using existing buildings, along with the expansion of public parking. In regard of social economic aspects, it is proposed to give each street specialized commercial theme. At the historic and cultural level, it is suggested to plan the pedestrian network which links the Fashion Street with surrounding historic elements.

• Korean Institute of Interior Design Journal
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• v.24 no.4
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• pp.124-134
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• 2015

This study aims to identify the characteristics of expression of place identity shown in public design of Choryang Ibagugil in Dong-gu, Busan and analyze them from physical aspects and from psychological ones. Choryang Ibagugil has special historicity indicating that it is a hillside road(Sanbokdoro) dwelling site created after the 6.25 Korean War and the quintessence of Busan. In addition, the site is a good example that used the topographic characteristics as they were and used the road for movement called as 'gil' to design public environment. Ibagugil connected to Sanbokdoro (i.e. Mangyang-ro) starting from the big road (Busan Station) where there was a large floating population represented the regional identity to public design by the medium of 'gil.' As a result of analyzing the characteristics of expression of place identity based on the current status discovered, our conclusions could be drawn as follows: First, place forms identity under interpersonal relationships and there is a story on the lives of people in the contexts between place and identity. Second, place identity is an independent specialty of a certain place and expression of place identity into public design makes the place more place-like. Ibagugil expressed its identity while adapting to the topographic characteristics of hillside road(Sanbokdoro). Third, adjacent public buildings were included into Ibagugil, thus highlighting the placeness, although it is considered that it is ambiguous to determine it as public design in the current-status analysis. Fourth, from the public value aspect, slumized hillside road(Sanbokdoro) was improved, which led to improvement in quality of environment and improvement in pride of local residents. Resultingly, it can be said that the place identity appeared in the public design of Choryang Ibagugil were the stories that happened in this place. Moreover, the indication of future image of how the place will be developed in the future makes the value of the place more significant. Therefore, in public design for expressing place identity, utilization of independent speciality of the site is considered to be an important factor. By doing so, 'place becomes a real place' and 'place can get an independent identity.' Going further, it comes to get the characteristics of 'being the place as it is.'

• Geophysics and Geophysical Exploration
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• v.14 no.4
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• pp.274-281
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• 2011

We analysed ground motions form Mw 4.3 earthquake around Backryoung Island for the seismic source focal mechanism and horizontal response spectrum. Focal mechanism of the Backryoung Islands area was compared to existing principal stress orientation of the Korean Peninsula and horizontal response spectrum was also compared to those of the US NRC Regulatory Guide (1.60) and the Korean National Building Code. The ground motions of 3 stations, including vertical, radial, and tangential components for each station, were used for grid search method of moment tensor seismic source. The principal stress orientation from this study, ENE-WSW, is consistent fairly well with that of the Korean Peninsula. The horizontal response spectrum using 30 observed ground motions analysed and then were compared to both the seismic design response spectra (Reg Guide 1.60), applied to the domestic nuclear power plants, and the Korean Standard Design Response Spectrum for general structures and buildings (1997). Response spectrum of 30 horizontal ground motions were used for normalization with respect to the peak acceleration value of each ground motion. The results showed that the horizontal response spectrum revealed higher values for frequency bands above 3 Hz than Reg. Guide (1.60). The results were also compared to the Korean Standard Response Spectrum for the 3 different soil types and showed that the vertical response spectra revealed higher values for the frequency bands below 0.8 second than the Korean Standard Response Spectrum (SD soil condition). However, through the qualitative improvements and quantitative enhancement of the observed ground motions, the conservation of horizontal seismic design response spectrum should be considered more significantly for the higher frequency bands.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1423-1436
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• 2010

The effects of meteorological and reclaiming conditions on the reduction of suspended particles are investigated using a computational fluid dynamics (CFD) model with the k-$\varepsilon$ turbulence closure scheme based on the renormalization group (RNG) theory. Twelve numerical experiments with different meteorological and reclaiming conditions are performed. For identifying the meteorological characteristics of the target area and providing the inflow conditions of the CFD model, the observed data from the automatic weather station (AWS) near the target area is analyzed. Complicated flow patterns such as flow distortion, horse-shoe vortex, recirculation zone, and channeling flow appeared due to the topography and buildings in the domain. Specially, the flow characteristics around the reclamation area are affected by the reclaiming height, reclaiming size and windbreak height. Reclaiming height affected the wind speed above the reclaiming area. Windbreak induces more complicated flow patterns around the reclaiming area as well as within the reclaiming area. In front of the windbreak, flow is distorted as it impinges on the windbreak. As a result, upward flow is generated there. Behind the windbreak, a secondary circulation, so called, a recirculation zone is generated and flow is reattached at the end of the recirculation zone (reattachment point). At the lower part of the recirculation zone, there is a reverse flow toward the windbreak. Flow passing to the reattachment point starts to be recovered. Total amounts of suspended particles are calculated using the frictional and threshold frictional velocities, erosion potential function, and the number of surface disturbance. In the case of a 10 m-reclaiming and northerly wind, the amount of suspended particles is largest. In the presence of 5 m windbreak, the friction velocity above the reclaiming area is largely reduced. As a result, the total amount of the suspended particles largely decreases, compared to the case with the same reclaiming and meteorological conditions except for the windbreak The calculated suspended particle amounts are used as the emission rate of the dispersion model simulations and the dispersion characteristics of the suspended particles are analyzed.

• Journal of architectural history
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• v.13 no.2 s.38
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• pp.57-70
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• 2004

Since Korea disclaimed to open the ports, Korean architecture has met the impetuous transformation. Although there would be various factors of this transformation, the new-coming architecture by missionary seemed to be a significant one, and many researches have been carried out on this theme in diverse viewpoints. However, because these researches have preponderated on the Catholic tradition, it is deficient for clarify the whole history of mission architecture. Therefore, this research has the meaning to enrich the history of Korean modern architecture by making balance. First of all, this paper is focused on the activities of one missionary, Graham Lee. He is a practical missionary at the beginning, his architecture made a critical influence in Korean traditional architecture. Graham Lee was born in Rock Island, Illinois, 1861, and he determined to become a missionary through grown up. He spent his boyhood by working as a plumber for his purpose and studied in a university afterward. Graduating of McComick Theological Seminary, he was nominated as a pioneer of Pyeng Yang Mission Station and set foot in Korea, September of 1892. Since then he started to erect missionary facilities in Pyeng Yang, such as Well House(1898), Pyeng Yang Central Church(1900-1901), Pyeng Yang Academy(1902). These all his works are designed with eclectic style which shows western and Korean traditional style intermingled. This unique characteristic made a profound influence to the Korean mission architecture afterwards. Especially, the L-type plan of Pyeng Yang Central Church, which is first shown by him, is recognized very unique, and this plan type had been spread all over the country. Therefore the L-type plan became the peculiar feature of the early Korean churches. Furthermore, working with Korean carpenters, he taught them new skills of modem buildings. After that, they were expanded out northern part of Korea and took the roles of master builders. According to this expansion, his particular style had got spread and had been settled as a unique eclectic style in Korean modern architecture. In the conclusion, he is evaluated to be a critical pioneer missionary, who left a big influence on the frame work of Korean modern architecture in the transitional times.

• Spatial Information Research
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• v.21 no.3
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• pp.89-101
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• 2013

Recently, importance of indoor space is on the rise, as larger and more complex buildings are taking place due to development of building technology. Accordingly, range of the target area of spatial information service is rapidly expanding from outdoor space to indoor space. Various demands for indoor spatial information are expected to be created in the future through development of high technologies such as IT Mobile and convergence with various area. Thus this research takes a look at available methods for building indoor spatial information and then builds high accuracy three-dimensional indoor spatial information using indoor high accuracy laser survey and 3D vector process technique. The accuracy of built 3D indoor model is evaluated by overlap analysis method refer to a digital map, and the result showed that it could guarantee its positional accuracy within 0.04m on the x-axis, 0.06m on the y-axis. This result could be used as a fundamental data for building indoor spatial data and for integrated use of indoor and outdoor spatial information.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.9
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• pp.757-765
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• 2017

GNSS (Global Navigation Satellite System) Position Accuracy depends on pseudo-range measurement and DOP (Dilution Of Precision) which indicates about navigation satellite geometry. Pseudo-Range has many error sources such as satellite clock, orbit, ionosphere, troposphere, multipath and so on. For the improvement of the accuracy, user can use corrected pseudo-range in DGPS (Differential Global Positioning System), which is one of the relative positioning methods. But, stationary station is needed in relative positioning. In case of DOP, Signal reception environment is important. If receiver sets in the center of city, it could be interrupted reception by buildings. This environment leads to decrease the number of visible satellites and to increase DOP. This paper proposes the concept of GNSS positioning with virtual satellites which have usable VRM (Virtual Range Measurement). Via virtual satellites and VRM, users could get an accurate position. Especially referred virtual satellites constellation has an effect on vertical error.