• Steel and Composite Structures
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• v.35 no.3
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• pp.305-325
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• 2020

Beams of steel frame-tube structures (SFTSs) typically have span-to-depth ratios of less than five. This makes a flexural beam unsuitable for such an application because the plastic hinges at the beam-ends cannot be adequately developed. This leads to lower ductility and energy dissipation capacities of SFTSs. To address this, SFTSs with bolted web-connected replaceable shear links (SFTS-BWSLs) are proposed. In this structural system, a web-connected replaceable shear link with a back-to-back double channel section is placed at the mid-length of the deep beam to act as a ductile fuse. This allows energy from earthquakes to be dissipated through link shear deformation. SFTS and SFTS-BWSL buildings were examined in this study. Several sub-structures were selected from each designed building and finite element models were established to study their respective hysteretic performance. The seismic behavior of each designed building was observed through static and dynamic analyses. The results indicate that the SFTS-BWSL and SFTS have similar initial lateral stiffness and shear leg properties. The SFTS-BWSL had lower strength, but higher ductility and energy dissipation capacities. Compared to the SFTS, the SFTS-BWSL had lower interstory drift, base shear force, and story shear force during earthquakes. This design approach could concentrate plasticity on the shear link while maintaining the residual interstory drift at less than 0.5%. The SFTS-BWSL is a reliable resistant system that can be repaired by replacing shear links damaged due to earthquakes.

• Journal of the Korea Institute of Building Construction
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• v.15 no.2
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• pp.185-192
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• 2015

Expansion joint is the essential element of the bridge in many cases. When the bridge faces chloride of preventing freezing on the surface of the bridge, the expansion joints is damaged significantly, thus this reduces service life and increases maintenance cost of the bridge. As a solution of this problem, new technology using high ductile materials for the joint without expansion joint was developed and in this research, crack control performance, preventing leaking after the cracking, and chloride resistance were experimentally evaluated. As a result of the experiment, with PCM and FRC materials, the connecting joint suffered poor crack dispersion and severe damage by the chloride penetration while with high-ductile material, the connecting joint dispersed the tensile deformation to microcracks stably up to 7.5mm. Furthermore, under the sever conditions, the leaking was prevented and penetration of chloride ions was prevented after the crack occurred.

• Korean Journal of Environment and Ecology
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• v.22 no.2
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• pp.128-137
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• 2008

The purpose of this study is to analyze the effect of hiking trails on forest landscape's fragmentation, based on which also to assess the landscape-ecology-based integrity by small drainage area by selecting Bukhansan National Park as a survey target. The results of effect analysis are as follow; size of forest patch decreased; the density of patch and edge increased; patch shape became complicated; the dimensions of core area noticeably decreased and proximity degree between patch increased after trail-building. In addotion, the assessment results of overall landscape ecology-based integrity by small drainage basin showed that the Bukhansan catchment area was highest making 3.7 point, while Gugi catchment area was rated the lowest making 1.6 point. Putting the above results together, it is necessary to prohibit the opening up of unnecessary trails and to make room for ecological restoration of damaged and disturbance area to their original state as nature goes for landscape-ecology-based conservation and management of forests.

• Journal of architectural history
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• v.19 no.6
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• pp.7-22
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• 2010

This study includes a review of the relevant literature and data on the Gyeolseong Eupseong, a coastal castle town of the Joseon Period. During the process of building the Gyeolseong Eupseong, Eupchi(administrative office) was transferred to several different locations for the following reasons:. first, to strengthen defensive capabilities by utilizing the locational advantages of the Seokdang Mountain Fortress, second, to secure sufficient space for holding the castle and have access to water in times of emergencies, third, to strengthen coastal defence by utilizing geographical advantages. Most of the Gyeolseong Eupseong was damaged during the Japanese colonial period. At present, there remain only part of the castle's facilities and some facilities that were restored later in modern times; 4 building sites have been identified. Remaining and destructed buildings can be identified through old maps(the local maps of 1872) and Zirizi and Eupzi(geography books). Also identified were 2 castle gate sites where a 1,500m-long stone castle wall and an ongseong(a crescent-shaped defensive structure), 5 chiseongs, and a most were constructed. The Gyeolseong area is assumed to have been a strategic foothold to defend the west coast from the days before the Three Kingdom Period. However it is very difficult to find any records created before the Joseon Period. Therefore, the time of the restoration of the Eupchi should be determined based on records created in the late Joseon Period. Finally, excavation work needs to be done to identify the locations of the castle's facilities.

• Journal of the Korea Safety Management & Science
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• v.16 no.2
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• pp.211-216
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• 2014

Using a high-rise building water piping after hydrostatic test of the reliability of the leak to be completed if the pressure is maintained until the leak is not commercially available considered. Due to the nature of high-rise buildings and the construction period will take several years from the lower levels of use of the water supply and fire fighting water pipe construction is in progress, the order of which I do most of the first pipe to the construction and more than three years. So kind of riser pipe is complete, install the valve in the basement by installing an automatic pump to maintain a constant pressure after hydrostatic test and after each floor plumbing piping is complete, the progress of the hydrostatic test without undergoing a separate branch pipe the valve is opened automatically when the number of the pressing pressure of the structure. I kind of do and keep working pressure of pipe until the completion of the construction work to keep the damage to human error when it is intended to prepare. In winter, the frost protection and an alternative to drainage water pipe is damaged or deformed, even if unaware of the finishing work to the building, the use of the damage caused by a leak in a after construction of finish work to be expected. Alternative to reduce this damage if the pressure test without fear of freezing to help maintain long-term commercial pressures may be considered.

• The Journal of the Acoustical Society of Korea
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• v.32 no.3
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• pp.227-236
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• 2013

In this paper, we present a vocal suppression algorithm that can enhance the quality of music signal coded using Spatial Audio Object Coding (SAOC) in Karaoke mode. The residual vocal component in the coded music signal is estimated by using a cross prediction method in which the music signal coded in Karaoke mode is used as the primary input and the vocal signal coded in Solo mode is used as a reference. However, the signals are extracted from the same downmix signal and highly correlated, so that the music signal can be severely damaged by the cross prediction. To prevent this, a psycho-acoustic disturbance rule is proposed, in which the level of disturbance to the reference input of the cross prediction filter is adapted according to the auditory masking property. Objective and subjective test were performed and the results confirm that the proposed algorithm offers improved quality.

• Journal of the Korea Institute of Building Construction
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• v.8 no.5
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• pp.85-91
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• 2008

Prepacked concrete has recently been used in the special constructions fields such as underwater concrete work, heavy-weight concrete work, underground structure work, partial repair works for damaged reinforced concrete structures. and polymer-modified mortars have been employed as grouting mortars for the prepacked concrete. The purpose of this study is to recommend the optimum mix design of polymer-modified grouting mortars for prepacked concrete. Polymer-modified mortars using SBR and EVA emulsions as admixture of grouting mortars for prepacked concrete are prepared with various mix proportions such as sand-binder ratio, fly ash replacement ratio, polymer-binder ratio. and tested for flowability, viscosity of grouting mortars, bleeding ratio, expansion ratio, flexural and compressive strengths of grouting mortars and compressive and tensile strengths of prepacked concretes. From the test results, it is apparent that polymer-modified mortars can be produced as grouting mortars when proper mix design is chosen. We can design the mix proportions of high strength mortars for prepacked concrete according to the control of mix design factors such as type of polymer, polymer-binder ratio, sand-binder ratio and fly ash replacement ratio. Water-binder ratio of plain mortars for a constant flowability value are in the ranges of 43% to 50%. SBR-modified mortar has a little water-binder ratios compared to those of plain mortar, however, EVA-modified mortar needs a high water-binder ratio due to a high viscosity of polymer dispersion. The expansion and bleeding ratios of grouting mortars are also controlled in the proper value ranges. Polymer-modified grouting mortars have good flexural. compressive and tensile strengths, are not affected with various properties with increasing fly ash replacement to cement and binder-sand ratio. In this study, SBR-modified grouting mortar with a polymer-binder ratio of 10% or less, a fly ash replacement of 10% to cement and a sand-binder ratio of 1.5 is recommended as a grouting mortar for prepacked concrete.

• Journal of the Korea Institute of Building Construction
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• v.17 no.3
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• pp.219-225
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• 2017

The durability factors of concrete has been researched by many researchers. Among the chemical ingression by acid, alkali, or salt, specially the ingression by sulfate has been actively studied and reported. Generally, for the oil type chemical, it is reported to cause the excessive expansion of cement mortar and further to cause the collapse, while there was no enough research on influence of oil type, relationship with microstructure of mortar, and collapse pattern. Therefore, in this research, using the various oils from general market, the degradation properties of the mortar mixtures with various mix designs were evaluated. according to the experiment, Bio diesel damaged worst and the mix design with less cement content showed the worst damage against oils.

• Journal of the Korea Institute of Building Construction
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• v.18 no.6
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• pp.569-576
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• 2018

In modern society, a huge number of the buildings have been constructed with RC structure. RC structures have many structural instabilities due to earthquake, typhoon, construction fault, design phase errors. Therefore, many reinforcement methods are being implemented to solve this problem. In the reinforcement method, the organic epoxy adhesive used in the FRP reinforcing method is abruptly damaged when exposed to high temperature, which is directly connected to the fall of the reinforcing material. Therefore, the present study was conducted to develop inorganic refractory mortar with a certain level of adhesion ability to reduce the heat transferred to FRP reinforcement when exposed to high temperatures. As a result of the test, it showed high adhesion strength at room temperature condition with the inclusion of EVA resin, and showed no performance deterioration up to about $300^{\circ}C$ even under heating conditions. Also, it was confirmed that the backside temperature was lower as the thickness increased, and converged to a constant temperature of about $780^{\circ}C$ after 2 hours of heating.

• Structural Engineering and Mechanics
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• v.85 no.6
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• pp.793-808
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• 2023

Türkiye is located in a region where destructive earthquakes are frequently experienced due to its geological characteristics and geographical location. Therefore, considering the possibility of a devastating earthquake at any time, determining the reinforced concrete (RC) building seismic safety, constructed before or after the current seismic buildings code, is one of the most important issues to be completed firstly. For this purpose, rapid assessment methods developed to quickly determine the seismic safety of buildings are available in the literature. Comparison of the principles of Principles of the Determination of Risky Structures-2019, Column and Wall Index Method, P25 Scoring Method and Improved Discriminant Analysis Method, which are among these methods, have been aimed within the scope of this study. Within the scope of this paper, a total of 43 buildings in the Yalova/Çınarcık region of Türkiye that the damage level was determined by street observation method immediately after the 1999 Kocaeli (Izmit) Earthquake; 15 buildings with heavy damage and 28 buildings with moderate damage were examined by rapid assessment methods. Although the risk detection difference was not separated as a clear line in any of the methods used, the results obtained from the rapid assessment methods are evaluated as being compatible with the detected after earthquake structural seismic behavior of the buildings. The PDRS-2019 and column and wall index method gave the most approximate results. In the results obtained from the analyzes; structural features such as number of floors, frame continuity, soft/weak story irregularity, effective shear strength area, existence of heavy overhangs in plan, type of structural system have been found to be significantly effective on the earthquake behavior of buildings.