• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5306-5313
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• 2011

Most previous studies for finding optimal design parameters of a tuned mass damper(TMD) have been focused on the harmonic excited single-degree-of freedom system. In this study, optimal values of damping ratio and tuning frequency ratio of a TMD applied to control a seismically excited structure are investigated through numerical analyses. Considering that the structural responses due to earthquake loads are strongly dependent on the soil condition, the site effects on the optimal parameters of the TMD are studied and compared to those presented by previous studies. Numerical analyses results indicate that better control performance can be obtained by using the parameters proposed by this study in the seismic application of the TMD.

• Earthquakes and Structures
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• v.13 no.2
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• pp.119-130
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• 2017

This paper presents a numerical investigation on the seismic behavior of isolated bridges with supplemental viscous damping. Usually very large displacements make seismic isolation an unfeasible solution due to boundary conditions, especially in case of existing bridges or high risk seismic regions. First, a suggested optimal design procedure is introduced, then seismic performance of three real bridges with different isolation systems and damping levels is investigated. Each bridge is studied in four different configurations: simply supported (SSB), isolated with 10% damping (IB), isolated with 30% damping (LRB) and isolated with optimal supplemental damping ratio (IDB). Two of the case studies are investigated under spectrum compatible far-field ground motions, while the third one is subjected to near-fault strong motions. With respect to different design strategies proposed by other authors, results of the analysis demonstrated that an isolated bridge equipped with HDLRBs and a total equivalent damping ratio of 70% represents a very effective design solution. Thanks to confirmed effective performance in terms of base shear mitigation and displacement reduction under both far field and near fault ground motions, as well as for both simply supported and continuous bridges, the suggested control system provides robustness and reliability in terms of seismic performance also resulting cost effective.

• Smart Structures and Systems
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• v.23 no.3
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• pp.295-306
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• 2019

Shanghai Tower is a 632-meter super high-rise building located in an area with wind and active earthquake. A sophisticated structural health monitoring (SHM) system consisting of more than 400 sensors has been built to carry out a long-term monitoring for its operational safety. In this paper, a reduced-order model including 31 elements was generated from a full model of this super tall building. An iterative regularized matrix method was proposed to tune the system parameters, making the dynamic characteristic of the reduced-order model be consistent with those in the full model. The updating reduced-order model can be regarded as a benchmark model for further analysis. A long-term monitoring for structural dynamic characteristics of Shanghai Tower under different construction stages was also investigated. The identified results, including natural frequency and damping ratio, were discussed. Based on the data collected from the SHM system, the dynamic characteristics of the whole structure was investigated. Compared with the result of the finite element model, a good agreement can be observed. The result provides a valuable reference for examining the evolution of future dynamic characteristics of this super tall building.

• Journal of The Korea Institute of Healthcare Architecture
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• v.27 no.1
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• pp.53-63
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• 2021

Purpose: Intensive Care Unit (ICU) is an important field of inpatient treatment, in which critically ill patients have been treated intensively with advanced medical technology. The level of treatment in the intensive care unit and the modernization of related facilities are important indicators of the quality of medical care. At present, when regional public hospitals are expanding frequently, reasonable planning of ICU has become an important part of medical institutions that treat ICU. The purpose of this study is to provide basic data on the net area of each unit, which can be used in ICU building planning. Methods: The investigation and analysis of the ICU were conducted in 12 medical institutions, based on theoretical analysis based on relevant guidelines and literature, and analysis of actual space composition and net area through architectural drawings. Results: This research provides basic data, such as the location relationship with other important departments, regional division, spatial composition, the relationship between main activities and regions, the composition of facilities in the region, and the area and proportions of each region. Implications: It is expected that the results of this article will provide effective reference materials for the reasonable spatial organization and effective operation of the intensive care units of ordinary public hospitals of different sizes in the future.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.2
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• pp.1-9
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• 2022

A novel steel-pipe energy pile is introduced, in which the deformed rebars for main reinforcing are replaced with steel pipes in a large diameter cast-in-place energy pile. Here, the steel pipes act as not only reinforcements but also heat exchangers by circulating the working fluid through the hollow hole in the steel pipes. Under this concept, the steel-pipe energy pile can serve a role of supporting main structures and exchanging heat with surrounding mediums without installing additional heat exchange pipes. In this study, the steel-pipe energy pile was constructed in a test bed considering the material properties of steel pipes and the subsoil investigation. Then, the thermal performance test (TPT) in cooling condition was conducted in the constructed energy pile to investigate thermal performance. In addition, the thermal performance of the steel-pipe energy pile was compared with that of the conventional large diameter cast-in-place energy pile to evaluate its applicability. As a result, the steel-pipe energy pile showed 11% higher thermal performance than the conventional energy pile along with much simpler construction processes.

• Journal of The Korea Institute of Healthcare Architecture
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• v.28 no.4
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• pp.51-60
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• 2022

Purpose: This study aims to analyze and supplement the standards related to healthcare facilities, negative pressure isolation wards, and emergency treatment facilities. In addition, through environmental investigations, analysis of emergency remodeling cases centered on the structural and HVAC characteristics of healthcare facilities is conducted. Methods: Domestic and foreign standards related to healthcare facilities were analyzed. Field investigations and architectural drawing analysis of general and emergency treatment facilities were conducted. Results: Healthcare facilities have different space classifications and air conditioning methods depending on the site situation. Emergency treatment facilities are classified into cases where the HVAC system is remodeled and portable negative pressure unit is installed, and some facilities did not meet the standards for differential pressure and air change rate. Implications: When developing emergency remodeling technology, remodeling and safety evaluation guidelines, it is considered possible to propose clearer guidelines for emergency remodeling treatment facilities for infectious diseases in Korea by referring to the results of this study.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.59-60
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• 2020

Large fires continue to spread throughout the building, including the fire in Uijeongbu in 2015, the fire in Jecheon in 2017, and the fire in Miryang in 2018. According to the above fire case investigation, major problems were the fire resistance performance of compartment members such as fire doors, the fire spread due to damage to exterior wall openings, and smoke spread through vertical openings. However, in South Korea, only specification design is implemented for buildings that are not subject to performance design. In addition, the analysis of the fire resistance performance standards of building members in the specification design showed that fire doors were not specified in detail for 60 minutes of insulation performance and 60 minutes of fire resistance performance of E/V doors, limiting the prevention of fire spread. Therefore, the purpose of this research is to prepare measures to prevent the spread of fire by presenting simple transplants for calculating the required fire time according to the architectural design conditions for the performance design of the components of the fire room according to the purpose of use of the front of the building.

• Journal of The Korea Institute of Healthcare Architecture
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• v.30 no.3
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• pp.57-65
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• 2024

Purpose: This study aims to evaluate the barrier-free environment at Fukui University's Bunkyo Campus, focusing on the mobility of students using manual wheelchairs. Methods: Data were collected on architectural plans, barrier-free facilities, and class schedules at Fukui University's Bunkyo Campus. Measurements included step heights, slopes, and the accessibility of classroom furniture for manual wheelchairs. Mobility was assessed by timing the movement between 19 classrooms used in the second semester of 2022 during breaks and summer vacation. Results: This study highlights that while Fukui University's Bunkyo Campus has some barrier-free buildings, significant improvements are needed. Issues include inadequate elevators, hand operated doors, and multi-purpose restrooms, as well as inefficient classroom's furniture layouts for wheelchair users. To enhance accessibility, future efforts should focus on reducing elevator wait times, automating doors, and optimizing classroom designs. Implications: The study indicates that Fukui University's Bunkyo Campus needs significant improvements in barrier-free accessibility. It provides foundational data for future detailed planning and implementation. Enhanced campus accessibility and better classroom designs are crucial for equal learning environments. Similar issues may exist at other Japanese universities, warranting broader investigation.

• Journal of the Korean GEO-environmental Society
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• v.16 no.1
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• pp.17-27
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• 2015

Recently, Korean government has tried out to set up earthquake hazards prevention system. In the system, several geotechnical hazard maps including liquefaction hazard map and landslide hazard map for the whole country have drawn to consider the domestic seismic characteristics. To draw the macro liquefaction hazard map, big data of site investigations in metropolitan areas and provincial areas has to be verified for its application. In this research, we carried out site response analyses using 522 borehole site investigation data in S city during a desirable earthquake. The soil classification was separately compared to shear wave velocity considering the uncertainty of site investigation data. Probability distribution and statistical analysis for the results of site response analyses was applied to the feasibility study. Finally, we suggest a new site amplification coefficient, hereby presented with the similar results of liquefaction hazard mapping using the calculated liquefaction potential index by the site response analyses. Above-mentioned study will be expected to help to follow research and draw liquefaction hazard map in moderate seismic region.

• Journal of the Korea Concrete Institute
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• v.27 no.5
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• pp.521-530
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• 2015

Design of fiber reinforced ultra-high strength concrete members should be verified with analytical or experimental methods for safety. Members with compressive strength larger than limitation of current design code usually be designed with analytical verification using stress-strain relation of concrete and reinforcements. For this purpose, mechanical characteristics of steel fiber reinforced ultra-high strength concrete were defined under uniaxial compression. Mix proportions of test specimens were based on reactive powder concrete and straight steel fibers were mixed with different volume fraction. Compressive strength of matrix were distributed from 80 MPa to 200 MPa. Effect of fiber inclusion were investigated : increase of compressive strength of concrete, elastic modulus and strain corresponding to peak stress. For the wide range application of investigation, previously tested test specimens were collected and used for investigation and estimation equation. Based on the investigation and evaluation of previous research results and estimation equation of mechanical characteristics of concrete, regression equations were suggested.