• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2006.03a
• /
• pp.125-132
• /
• 2006

To estimate the local site effects at two town fortress areas where stone parapets were collapsed during historical earthquakes, site characteristics were evaluated using borehole drillings and seismic tests and equivalent-linear site response analyses were conducted based on the shear wave velocity (Vs) profiles determined from site investigations. The study sites are categorized as site classes C and B according to the mean Vs to 30 m ranging from 500 to 850 m/s, and their site periods are distributed in short period range of 0.06 to 0.16 sec. For site class C in the study areas, the short-period (0.1-0.5 sec) and mid-period (0.4-2.0 sec) site coefficients, $F_{\alpha}$ and $F_\nu$ specified in the Korean seismic design guide, underestimate the ground motion in short-period band and overestimate the ground motion in mid-period band, respectively, due to the characteristics showing high amplification in short period range, which can result in the collapse of stone parapets having the short natural period.

• Journal of the Ergonomics Society of Korea
• /
• v.18 no.3
• /
• pp.87-103
• /
• 1999

The present study employed an experimental usability testing technique to explore cognitive engineering characteristics of WWW. Based on the results of our previous study which employed non-experimental methods such as questionnaire and heuristic evaluation method, this study used a behavioral performance-measurement technique to evaluate the usability of a domestic web-site design. Specifically, we revised the menu and document structure of the original 'Movie-Friend' site to solve the design problems which were extracted from the results of the heuristic evaluation method of our previous study. Exp. 1 compared the relative navigation efficiency of the original frame menu site and the revised pop-up toolbar site, and Exp. 2 compared the toolbar menu site and the revised frame site. As a result of Exp. 1, the revised pop-up toolbar site showed improved navigation efficiency compared to the original site, as indicated by the mean latency and the number of pathways to reach the target page. However, we found no performance difference between the frame site and toolbar site in Exp. 2.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.24 no.2
• /
• pp.179-185
• /
• 2020

Recently, in order to improve the performance of the Earthquake Early Warning System (EEWS) and to supplement the effects of earthquake disaster prevention in epicenters or near epicenters, development of on-site EEWS has been attempted. Unlike the national EEWS, which is used for earthquake disaster prevention by using seismic observation networks for earthquake research and observation, on-site EEWS aims at earthquake disaster prevention and therefore requires efficient design and evaluation in terms of performance and cost. At present, Korea lacks the necessary core technologies and operational know-how, including the use of existing EEWS design criteria and evaluation methods for the development of On-Site EEWS as well as EEWS. This study proposes hardware and software design directions and performance evaluation items and methods for seismic data collection, data processing, and analysis for localization of On-Site EEWS based on the seismic accelerometer requirements of the Seismic and Volcanic Disaster Response Act.

• Korean Journal of Construction Engineering and Management
• /
• v.24 no.4
• /
• pp.25-34
• /
• 2023

The purpose of this study is to calculate and compare construction costs for On-Site Construction and Off-Site Construction in Plant Project. For this purpose, the target for calculating the construction cost was limited to the Pipe Rack(Steel Structure and Piping). The results derived according to the purpose of the study are as follows. 1)The direct construction cost for On-Site Pipe Rack construction was KRW 56 billion, with Steel Structure KRW 25.1 billion and Piping KRW 30.8 billion won. 2)Comparing the rate of change between On-Site Construction and Off-Site Construction, material costs increased by 1.9% and expenses by 192.1%, but labor costs decreased by -9.1%, resulting in a total direct construction cost increase of 8.4%. These results can be used as reference data to check the current status of the increase or decrease in construction costs when constructing Pipe Racks as Off-Site Construction.

• International conference on construction engineering and project management
• /
• 2024.07a
• /
• pp.1283-1283
• /
• 2024

Recently, construction sites have faced significant challenges due to arbitrary changes and poor communication between general contractors and subcontractors. This study proposes a technological solution by integrating Unmanned Ground Vehicles (UGVs) into the existing workflow of apartment construction. By analyzing current processes, we identified a scenario where UGVs, equipped with LiDAR (Light Detection and Ranging) systems, can generate and provide real-time 3D models of construction sites. These models can be linked with extended reality (XR) technology or office PCs for intuitive comparisons between digital and actual site conditions as a digital twin of the construction site. The study suggests an improved construction process that enhances contractors' understanding and on-site efficiency and enables managers to monitor progress effectively. To address challenging terrain on construction sites, a caterpillar driven UGV was developed, equipped with stereo cameras, a LiDAR sensor for scanning and gathering environmental data, and an embedded PC for data processing. Utilizing SLAM (Simultaneous Localization and Mapping) technology, the UGV autonomously navigates and scans the site at night, minimizing disruptions. Additionally, an embedded system analyzes images from stereo cameras to assess the quality of construction, mapping the findings onto 3D models. This innovation allows site managers to efficiently verify construction quality and identify issues without manual inspections, significantly improving site management efficiency.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.10a
• /
• pp.154-162
• /
• 2005

In this paper, site response analyses were performed based on equivalent linear technique using the shear wave velocity profiles of 162 sites collected around the Korean peninsula. The site characteristics, particularly the shear wave velocities and the depth to the bedrock, are compared to those in the western United States. The results show that the site-response coefficients based on the mean shear velocity of the top 30m ($V_{S30}$) suggested in the current code underestimates the motion in short-period ranges and overestimates the motion in mid-period ranges. Also the current Korean code based on UBC is required to be modified considering site characteristics in Korea for the reliable estimation of site amplification. From the results of numerical estimations, new regression curves were derived between site coefficients ($F_a$ and $F_v$) and the fundamental site periods, and site coefficients were grouped based on site periods in the regions of shallow bedrock. The standard deviations of the proposed method was reasonable compared to site classification based on $V_{S30}$. Finally, new site classification system is recommended based on site periods for regions of shallow bedrock depth in Korea.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2000.10a
• /
• pp.98-107
• /
• 2000

Free-field ground motion during earthquake is significantly affected by the local site conditions and it is essential for the seismic design to perform the ground response analysis In this study, ground response analyses based on the equivalent linear method were carried out to evaluate the effects of various ground conditions on the site amplification. Four major factors including the depth of the site(very soft and dense soil), the impedance ratio between soil layer and bed rock, linear analysis versus equivalent linear analysis, and the location of soft soil layer were deeply discussed. Based on the analysis results, the importance of various local site conditions on the site amplification was emphasized.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2002.03a
• /
• pp.51-58
• /
• 2002

The relative site amplification factors in southern Korea were determined from coda waves using coda normalization method. The seismograms of 15 events at 79 stations were used in this study. Seismogram envelopes were obtained by the Hilbert transform of bandpass-filtered velocity seismograms with frequency bands at 1-2Hz, 2-4Hz, 4-8Hz, 8-l6Hz and 16-32Hz. The envelopes were stabilized by application of moving-average scheme with time window of 1 second. The relative amplitudes of seismogram envelope were computed by dividing the amplitude of seismogram envelope at one site by the amplitude of seismogram envelope at reference site. The relative site amplification factors were obtained by taking averages of the relative amplitude. Values of relative site amplification factors in southern Korea are generally low in western area and high in eastern area.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.1 no.1
• /
• pp.14-19
• /
• 1990

A site attenuation measurement system has been developed and evaluated. The system uses selfresonant dipole antennas and baluns. Using the system we measured the site attenuations of the KSRI open area test site. The measured results agree with calculated data within $\pm$3dB , so the site can be used for EMI/EMC measurements and antenna calibrations.

• The Journal of the Society of Korean Medicine Diagnostics
• /
• v.19 no.1
• /
• pp.47-54
• /
• 2015

Objective Wave reflection is an important factor that determines the shape of the pulse wave. The purpose of this study is to compare the conventional method used for estimating the reflection site of pulse with a cardiovascular simulator. Methods: In this study, cardiovascular simulator with one elastic tube was used. The pressure and flow was measured simultaneously at three different points. The measured data were used to the conventional methods to estimate the pulse wave reflection site. The results were compared with the known length which were the distances from the measured points to the end of tube. Results & Conclusions: There is a significant error with the time domain method. While, the reflection site with the frequency domain method was similar to the actual reflection site.