• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.35 no.4
• /
• pp.759-768
• /
• 2015

The ground motions of large dimensional structures such as long span bridges at different stations during an earthquake, are inevitably different, which is known as the ground motion spatial variation effect. There are many causes that may result in the spatial variability in seismic ground motion, e.g., the wave passage effect due to the different arrival times of waves at different locations; the loss of coherency due to seismic waves scattering in the heterogeneous medium of the ground; the site amplification effect owing to different local soil properties. In previous researches, the site amplification effects have not been considered or considered by a single-layered soil model only. In this study, however, the ground motion amplification and filtering effects are evaluated by multi-layered soil model. Spatially varying ground motion at the sites with different number of layers, depths, and soil characteristics are generated and the variation characteristics of ground motion time histories according to the correlation of coherency loss function and soil conditions are evaluated. For the bridge system composed of two unit bridges, seismic behavior characteristics are analyzed using the generated seismic waves as input ground motion. Especially, relative displacement due to coherency loss and site effect which can cause the unseating and pounding between girders are evaluated. As a result, considering the soil conditions of each site are always important and should not be neglected for an accurate structural response analysis.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.11 no.3
• /
• pp.229-242
• /
• 2009

Numerical analysis has been performed to estimate maximum settlement, maximum horizontal displacement and total settlement volume at the ground surface due to tunnel excavation varying ground condition, tunnel depth and diameter, and construction condition (volume loss at excavation face). The maximum surface settlement from the numerical analysis has been compared with the maximum settlement at tunnel crown considering ground condition, tunnel depth and diameter, and construction condition, and it has been also compared with the maximum horizontal displacement. In addition, the volume loss ($V_L$) at tunnel excavation face has been compared with the total surface settlement volume ($V_s$) with the variation of ground condition, tunnel depth, and tunnel diameter. The results from the numerical analysis have been compared with field measurements to confirm the applicability and validity of the results and by this comparison it is believed that the numerical results in this study can be utilized practically in analyzing the ground movements due to tunnel excavation.

• 한국방재학회:학술대회논문집
• /
• 2009.02b
• /
• pp.43-50
• /
• 2009

Strong ground motion attenuation relationship represents a comprehensive trend of ground shakings at sites with distances from the source, geology, local soil conditions, and others. It is necessary to develop an attenuation relationship with careful considerations of characteristics of the target area for reliable seismic hazard/risk assessments. In the study, observed ground motions from the January 2007 magnitude 4.9 Odaesan earthquake and the events occurring in the Gyeongsang provinces are compared with the previously proposed ground attenuation relationships in the Korean Peninsula to select most appropriate one. In the meantime, a few strong ground motion attenuation relationships are proposed and introduced in HAZUS, which have been designed for the Western United States and the Central and Eastern United States. The selected relationship from the ones for the Korean Peninsula has been compared with attenuation relationships available in HAZUS. Then, the attenuation relation for the Western United States proposed by Sadigh et al. (1997) for the Site Class B has been selected for this study. Reliability of the assessment will be improved by using an appropriate attenuation relation. It has been used for the earthquake loss estimation of the Gyeongju area located in southeast Korea using the deterministic method in HAZUS with a scenario earthquake (M=6.7). Our preliminary estimates show 15.6% damage of houses, shelter needs for about three thousands residents, and 75 life losses in the study area for the scenario events occurring at 2 A.M. Approximately 96% of hospitals will be in normal operation in 24 hours from the proposed event. Losses related to houses will be more than 114 million US dollars. Application of the improved methodology for loss estimation in Korea will help decision makers for planning disaster responses and hazard mitigation.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.3C
• /
• pp.167-174
• /
• 2010

In this study, numerical analysis has been performed to compare the ground movements in a single ground layer and multiple ground layers due to nearby tunnel excavation. The numerical analysis has been conducted in the different ground layer conditions considering different construction conditions (volume loss at excavation face), and the results of the maximum surface settlement and horizontal displacement have been compared considering the ground layer and construction conditions. In addition, the maximum surface settlement from the numerical analysis has been compared with the maximum settlement at tunnel crown considering the ground layer and construction conditions, and the maximum surface settlement has been also compared with the maximum horizontal displacement with the ground layer conditions. Besides, the volume loss($V_L$) at tunnel excavation face has been compared with the total surface settlement volume($V_s$) with the variation of ground layer condition. The results from the numerical analysis have been compared with field measurements and by this comparison it is believed that the numerical results in this study can be utilized practically in analyzing the nearby ground behavior in different ground layer and construction conditions due to tunnel excavation.

• Korean journal of food and cookery science
• /
• v.10 no.4
• /
• pp.346-350
• /
• 1994

This investigation was undertaken for the purpose of studying the effect of the addition of the powder(0, 1, 2, 3%)from fruit of paper mulberry(Broussonetia Kazinoki SieboId) on the hardness, cohesiveness, elasticity, gumminess, chewiness, cooking loss and sensory characteristics of cooked ground beef with or without soysauce. The results obtained were summerized as follows; Hardness, gumminess, chewiness, and cooking loss were decreased by increasing the percent of adding the powder from the fruit of paper mulberry. As a result of sensory evaluation for cooked ground beef, sample with powder from the fruit of paper mulberry showed the higher scores in most of the characteristics. And cooked ground beef added the powder from the fruit of paper mulberry with soysauce showed the higher decreasing rate of hardness than those of without soysauce.

• Journal of IKEEE
• /
• v.11 no.4
• /
• pp.252-256
• /
• 2007

We demonstrate that the effect of the PCB ground length and the cover is important in the performance of 2.4 GHz patch antennas. The Center frequency in the return loss shifts as much as 0.5 GHz, when the length of the PCB ground increases from 30 to 85 mm. The position of 10-dB bandwidth accordingly shifts to lower frequency region. Finally, the resonance at 2.4 GHz becomes stronger when the top cover exists. The radiation pattern of the patch antenna is also strongly affected by the ground structure and the existence of the top cover. In both the return loss and the radiation pattern, 3-dimensional simulations are shown to be an efficient tool.

• Natural Product Sciences
• /
• v.17 no.1
• /
• pp.38-44
• /
• 2011

The quality inspections items such as loss on drying, total ash, and acid-insoluble ash contents in herbal medicines, have a correlation with external sources of pollution, but are not themselves hazardous factors. Z-scores for standard normal distribution were used to investigate herbal medicines requiring quality control, which exceeds the regulatory limits of quality inspection. In total, 7,773 samples were analyzed based on plant parts. For the loss on drying, the numbers of items of herbal medicines requiring quality control are like these; 15 items for above-ground parts and 5 items for underground parts. For the total ash, 21 items for above-ground parts and 4 items for underground parts. For the acid-insoluble ash, 8 items for above-ground parts and 1 item for underground parts.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.7
• /
• pp.1558-1563
• /
• 2013

In this paper, we analyze the radio propagation path loss characteristics for the vertical electric dipole radiation over the perfect electric conductor(PEC) ground plane. Most research have been performed about the electromagnetic analysis of vertical electric dipole in free space for time domain or frequency domain. But this paper present the radio propagation path loss over PEC ground plane in time domain under the assumption of the vertical electric dipole as a base station. From the simulated results, the ground plane effect can change the location of near field from transmitting antenna and the transient responses at mobile are calculated. The results of this paper can be applied to surface radar or signal processing applications.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.37 no.2
• /
• pp.485-495
• /
• 2017

A development of underground space is very useful solution to slove problem occurred from ground surface enlargement in urban areas due to the growth of population, tunnelling is the most popular way and widely used. Researches regarding tunneling-induced pile-soil interactive behaviour have been conducted by many researchers. A study on pile axial force distribution due to tunnelling through laboratory model test, however, is being rarely carried out. In this study, therefore, authors investigate ground behaviour due to tunnelling below grouped pile subjected vertical load as well as pile axial force distribution. A concept of volume loss is used to express tunnel excavation, which is normally applied to 1~2% for tunnelling in soft ground. In this study, however, 10% of that applied to investigate failure mechanism. As a result of laboratory model test, a decrease of pile axial force occurs at 1.5% of volume loss, settlement of grouped pile is 1.2~4.7 times greater than the adjacent ground surface one. Ground deformations at 1.5% of volume loss are measured using Close Range Photogrammetry and compared with results from numerical analysis.

• Journal of the Society of Disaster Information
• /
• v.14 no.4
• /
• pp.399-408
• /
• 2018

Purpose: Recently, the ground subsidence has caused social problem, because it occurred life and economic damage. Method: Ground subsidence is different from a sink hole. Ground subsidence occurred cavities from loss of by groundwater flow, surface layer is collapsed due to relaxation and expansion. Results: According to the survey, the caused of ground subsidence are classified as ground cavities, surrounding ground relaxation and pipe joint failure. Conclution: Cavities of ground is mainly caused by cavities formed by rainfall induced infiltration of the heavy rainfall, loss of soil due to rise and fall of ground water level and repeated sewage runoff.