• Journal of the Society of Disaster Information
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• v.11 no.1
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• pp.45-54
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• 2015

In the case of railway facilities in cities such as a railway station or a bridge, the significance of design for reducing vibration and noise is getting more significant. The vibration control solution is in need especially for an elevated railway station to block vibration of a train and secondary noise effectively. Even though a vertical vibration isolation device is able to be applied effectively to railway facilities such as elevated railway stations which transfer vibration directly from a train to a structure, the development of the vertical device is much slower than a horizontal vibration isolation device. In this paper, a vibration isolation device using wedge type friction material which is currently developing to reduce train-induced vibration effectively is introduced and test results for verification of dynamic performance is also presented. The vibration test on a concrete structure equipped with the developed vibration isolation device is conducted through which the isolation performance and dynamic properties are verified and needs for improving the performance of the device is identified.

• Korean Journal of Crystallography
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• v.4 no.2
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• pp.54-62
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• 1993

The crystal shnture of dehydrated fully Cd2+-exchanged zeolite A evacuated at 2 × 10-6 Torr and 650℃ (a:12.189(2) A) and of its iodine sorption corrplex (a:12.168(2)A) have been netsmlmn by single uystal x-ray diffraction techliques in the cubic space group hkTn at 21(1)℃. The strutures were refined to final error indices, Ri:0.057 and R2 =0.063 with 186 reflections and Rl:0.082 and R2:0.085 with 181 reflections, respectively, for which 1>3σ(In both structure, six lie at two distinguished threefold axes of unit cell ten the crystal structure of an iodine sorption complex of Cd6-A four Cd2+ ions are recessed 0.69(1) A into the large cavity to complex each with from the (111) plane of 0(3), whereas two Cd2+ ions recessed 0.68(1) A into the sodalite unit Awximately 4.0 l3ions per nit cell are sorbed. Each bridge between a Cd2+ ion and 8-ring oxygens ((I-I-I)= 117(1) ˚ and 0(1)-I(1)-I(2)=172(1)). The near linear I-I-0 angle and its interatomic distance (I-0=3.57(3) A) are indicative of a weak charge transfer interacticn between the frarrework oxygen and iodine. The existence of In3 inside the large cavity indicates that the If ions and H ions may be produced by reaction of In vapor with water molecules which maybe associated with Cd2+ ions in partially dehydrated Cd6-A In3- ions may be produced by the combination of I- and I2.

• International Journal of Contents
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• v.11 no.2
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• pp.37-49
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• 2015

Sensors, equipment, ICT facilities and their corresponding software have a relatively short lifetime relative to that of constructional structure, so these devices have to be continuously fixed or exchanged during maintenance and management. Furthermore, software or analysis tools should be periodically upgraded according to advances in ICT and analysis technology. Conventional monitoring systems have serious problems in that it is difficult for site engineers to modify or upgrade hardware and analysis algorithms. Moreover, we depend on the original system developer when we want to modify or upgrade inner program structures. In this paper, we propose a novel design for integrated maintenance and management of a monitoring system by applying the mobile cloud concept. The system is intended for use in disaster prevention of constructional structures, including bridges, tunnels, and in traditional buildings in a local heritage village, we analyze the status of these structures over a long term or a short-term period as well as in disaster situations. Data are collected over a mobile cloud and future expectations are analyzed according to probabilistic and statistical techniques. We implement our integrated monitoring system to solve the existing problems mentioned above. The final goal of this study is to design and implement a monitoring system for more than 10,000 structures spread within Korea. Furthermore, we can specifically apply the monitoring system presented here to a bridge made from timber in Asan Oeam Village and a traditional house in Andong Hahoe Village to monitor for possible disasters. The entire system design and implementation can be developed on the LinkSaaS platform and the monitoring services can also be implemented on the platform. We prove that the proposed system has good performance by performing a TTA authentication test, web accommodation test, and operation test using emulated data.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.30 no.2
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• pp.46-63
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• 2012

The object of this study was to analyze the speciality of Korean traditional waterscape and unique landscape formed with reflection of the phases of the time sat the area of Juhabru(宙合樓) in Changdeok Palace as a basic research to find the prototype of Taeaek pond at Changdeok Palace and restoration of the palace. Originally, Taeaek pond at Changdeok Palace was constructed in KingInjo(仁祖) period as a name of Yongji(龍池), later it called Taeaek pond after King Sukjong(肅宗). There is an island as a symbol of the immortal isle, and Chungseojeong(淸署亭), Taiksujae(澤水齋) and Buyongjeong(芙蓉亭) which were built to view the waterscape in Taeaek pond. Buildings were built asymmetrical balance around Taeaek pond because of the morphological character of tetragonal pond. Arrangement of this area has a definite form of axial structure. Yeolgokwan(閱古觀) Gaeyuwa(皆有窩), pavilions, bridges, islands, Osumoon(魚水門) and Juhabru are located on the north and south axis, and island and Osumoon play a role as a intersection and form an east of west axis. In this study, manual of construction for an island and pavilions is provided by analyzing transformational process of island and pavilions at Taeaek pond. Furthermore, kings and officials used to statically enjoy the view around Taeaek pond area, but dynamic fishing and boating activity happened in King Jungjo(正祖) period. These historical backgrounds have an influence on the spatial organization of Taeaek pond. For instance, bridge between Taeaek pond and island was destroyed with the increase of the importance of boating. Symbolic structure around Taeaek pond means 'fish changes to dragon' and 'both of king and officials become one'. Taiksujai, carving fish, Osumoon and Juhabru are provided as a related spatial factors.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.163-170
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• 2006

Together with the trend of enhancement in domestic industrial development and economic progress due to import and export, the demand for construction of the roads, bridges, especially port facilities, and several coastal protection and ocean structures is increasing rapidly. MOMAF of Korean Government is driving construction of 9 new ports and renovation of the existing fishery ports. Among these structures most of bridge base, wharves, dolphins, quays, and jetties are being newly built of steel or concrete pile. As the base, supporting bulkheads, and piles are underwater after construction, it is difficult to figure out the status of structures and not enough to get maintenance and strengthen the structures. Every year, moreover, these works suck the government budget due to higher incomplete maintenance expense for protection from corrosions of structures and increased underwater construction period. For the purpose of cutting down the expense of government budget, it is necessary to extend the life cycle of the existing structures. Therefore, we developed a new method for maintenance of submerged structures near the waterline by allowing dry work environment with the floating caisson. The method shows easy to move around the working area and handle. It also showed not only a significant reduction maintenance expenses and time for anti-corrosion work but also better protection. This will be a milestone to reduce the maintenance and construction expenses for the shore and water structures.

• Journal of the Korean Geotechnical Society
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• v.37 no.11
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• pp.51-60
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• 2021

River scour erodes the soil around the pier, reducing the lateral bearing capacity of the pier and lowering the stability of the structure. In this study, in order to examine the effect of scouring on the stability of the structure, an experiment was performed to measure the natural frequency of the pier according to the excavation of the surrounding ground. Impact vibration test was conducted on the pier with the caisson foundation of the Mangyeonggang Bridge, which is scheduled to be demolished. Accelerometers were attached to the top, center, and bottom of the pier and the acceleration responses were measured by hitting those three points. The experimental results showed that the top hit showed consistent and reasonable results of the acceleration responses according to the hitting position. The measured accelerations were converted to the frequency domain through Fast Fourier Transform (FFT), and then the natural frequency was determined. In addition, to analyze the scour effect on the natural frequency of the pier, the ground around the pier was excavated and the natural frequency change was analyzed. As a result, the natural frequency showed the decreasing tendency according to the excavation depth, but the decrease was small due to the large stiffness of the caisson foundation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.5
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• pp.488-496
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• 2023

Ship and bridge structures are a type of long box-shaped structure, and resistance to vertical bending moment is a key factor in their structural design. In particular, because box girders are repeatedly exposed to irregular wave loads for a long time, the continuous collapse behavior of structural members must be accurately predicted. In this study, plastic collapse behavior, including buckling according to load changes of the box girder receiving pure bending moments, was analyzed using a numerical analysis method. The analysis targets were selected as three box girders used in the Gordo experiment. The cause of the difference was considered by comparing the results of the structural strength experiment with those of non-linear finite element analysis. This study proposed a combination of the entire and local sagging shape to reflect the effect of the initial sagging caused by welding heat that is inevitably used to manufacture carbon steel materials. The procedures reviewed in the study and the contents of the initial sagging configuration can be used as a good guide for analyzing the final strength of similar structures in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2A
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• pp.119-130
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• 2009

Seismic fragility curves of a structure represent the probability of exceeding the prescribed structural damage state for a given various levels of ground motion intensity such as peak ground acceleration (PGA), spectral acceleration ($S_a$) and spectral displacement ($S_d$). So those are very essential to evaluate the structural seismic performance and seismic risk. The purpose of this paper is to develop seismic fragility curves for PSC box girder bridges. In order to construct numerical fragility curve of bridge structure using nonlinear time history analysis, a set of ground motions corresponding to design spectrum are artificially generated. Assuming a lognormal distribution, the fragility curve is estimated by using the methodology proposed by Shinozuka et al. PGA is simple and generally used parameter in fragility curve as ground motion intensity. However, the PGA has not good relationship with the inelastic structural behavior. So, $S_a$ and $S_d$ with more direct relationship for structural damage are used in fragility analysis as more useful intensity measures instead of PGA. The numerical fragility curves based on nonlinear time history analysis are compared with those obtained from simple method suggested in HAZUS program.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.2
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• pp.23-32
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• 2020

The compression sensing technology, CAFB, was developed to obtain the raw signal of the target structure by compressing it into a signal of the intended frequency range. At this point, for compression sensing, the CAFB can be optimized for various reference signals depending on the desired frequency range of the target structure. In addition, optimized CAFB should be able to efficiently compress the effective structural answers of the target structure even in sudden/dangerous conditions such as earthquakes. In this paper, the targeted frequency range for efficient structural integrity monitoring of relatively flexible structures was set below 10Hz, and the optimization method of CAFB for this purpose and the seismic response performance of CAFB in seismic conditions were evaluated experimentally. To this end, in this paper, CAFB was first optimized using Kobe seismic waveform, and embedded it in its own wireless IDAQ system. In addition, seismic response tests were conducted on two span bridges using Kobe seismic waveform. Finally, using an IDAQ system with built-in CAFB, the seismic response of the two-span bridge was wirelessly obtained, and the compression signal obtained was cross-referenced with the raw signal. From the results of the experiment, the compression signal showed excellent response performance and data compression effects in relation to the raw signal, and CAFB was able to effectively compress and sensitize the effective structural response of the structure even in seismic situations. Finally, in this paper, the optimization method of CAFB was presented to suit the intended frequency range (less than 10Hz), and CAFB proved to be an economical and efficient data compression sensing technology for instrumentation-monitoring of seismic conditions.

• Journal of the Korean Institute of Landscape Architecture
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• v.49 no.2
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• pp.61-73
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• 2021

This study aimed to identify the landscape perception and landscape characteristics of users by utilizing SNS data generated by their experiences. Therefore, how to recognize the main places and scenery appearing on the island, and what are the characteristics of the main scenery were analyzed using online text data and photo data. Text data are text mining and network structural analysis, while photographic data are landscape identification models and color analysis. As a result of the study, First, as a result of frequency analysis of Bakji·Banwol-do topics, we were able to derive keywords for local landscapes such as 'Purple Bridge', 'Doori Village', and location, behavior, and landscape images by analyzing them simultaneously. Second, the network structure analysis showed that the connection between key and undrawn keywords could be more specifically analyzed, indicating that creating landscapes using colors is affecting regional activation. Third, after analyzing the landscape identification model, it was found that artificial elements would be excluded to create preferred landscapes using the main targets of "Purple Bridge" and "Doori Village", and that it would be effective to set a view point of the sea and sky. Fourth, Bakji·Banwol-do were the first islands to be created under the theme of color, and the colors used in artificial facilities were similar to the surrounding environment, and were harmonized with contrasting lighting and saturation values. This study used online data uploaded directly by visitors in the landscape field to identify users' perceptions and objects of the landscape. Furthermore, the use of both text and photographic data to identify landscape recognition and characteristics is significant in that they can specifically identify which landscape and resources they prefer and perceive. In addition, the use of quantitative big data analysis and qualitative landscape identification models in identifying visitors' perceptions of local landscapes will help them understand the landscape more specifically through discussions based on results.