• Economic and Environmental Geology
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• v.27 no.5
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• pp.491-498
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• 1994

The integral equation method is used for magnetotelluric (MT) modeling of a finite inhomogeneity in a two-layered earth. An integral equation relates the incident plane-wave field and the scattering currents in the three-dimensional (3-D) inhomogeneity through the electric tensor Green's function appropriate to a layered earth. This paper describes an effect of overburden and basement on MT responses of 3-D body. The effect of overburden is to reduce the detectability of target, and the reduction of detectability is more apparent for conductive overburden than for resistive one. The effect of basement, on the other hand, may enhance the anomaly due to 3-D body in the upper layer. In case of the resistive basement current perturbations about the body tend to be confined to the more conductive upper layer.

• Journal of the Korean Geotechnical Society
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• v.26 no.12
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• pp.61-70
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• 2010

A series of shaking table tests were conducted to estimate the seismic performance of soft ground deposits improved by stone column. The amplification of acceleration, shear strain, and shear wave velocity were evaluated to compare the seismic response of unimproved ground deposits with that of improved ground deposits. From the test results, it was shown that the stone column can prevent large shear deformation in ground deposits. However, it was also found that the acceleration of improved ground deposits may be amplified more than that of unimproved ground deposits when it was subjected to short periodic seismic wave. The results suggest that it is necessary to perform the ground response analysis with model experiments for both unimproved and improved ground deposits to evaluate the effect of stone column on the seismic performance of improved ground deposits.

• Journal of the Korean Geotechnical Society
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• v.39 no.12
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• pp.7-22
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• 2023

In this study, the limit range of input acceleration was investigated based on time domain and response spectrum analyses by considering the relative density, groundwater depth, and soil type. Special attention was paid to the input acceleration and shear modulus of soil, which affect pile behavior. The surrounding soil was identified as an elastoplastic material and subjected to FLAC3D analysis using the Mohr-Coulomb and Finn models as well as FB-Multiplier analysis using a nonlinear p-y curve for soil spring. Based on the analyses, the limit range of acceleration on the pile is much higher for SP soil than for SM soil, and the groundwater level tends to reduce the limit range of input acceleration, irrespective of soil conditions. The limit range of acceleration was mainly affected by the shear modulus. The limit range of acceleration with nonlinear soil behavior is proportional to the relative density of the surrounding soil.

• Korean journal of food and cookery science
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• v.13 no.2
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• pp.147-156
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• 1997

The purpose of this study was to investigate total life habits of male and female adult through questionaire. Questionaire was composed of items such as perception of body shape, food habits, preference habits, the concern of the health and weight control. For this study, the subjects were divided into three groups like low-weight group, standard-weight group, over-weight group according to their body shape. The results can be summarized as follows: 7.9% of the subjects were included in low-weight group, 55.2% in standard-weight group, 36.9% in over-weight group. The subjects' perception of ideal body shape was significantly different from that of actual body shape. Males were more satisfied with their body shape than females. Most of females were unsatisfied with present their body shape and prefered slim and long body shape. Males, specially low-weight group, had adherence to smoking, alcohol and health food compared with the other groups. Food habits of males were considered to be fair compared with those of females. Meal amounts of over-weight group were significantly higher than those of the others. Low-weight group took more snacks and took a stong dislike of food. Males exercised hard and thought their health status to be fair. Low-weight group of males and standard-weight group of females considered their health status to be bad. 69% of the subjects were concerned about weight control. Low-weight group of males had a desire to gain weight while most of females had a desire to lose weight.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.187-195
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• 2015

The gas explosions in offshore installations are known to be very severe according to its geometry and environmental conditions such as leak locations and wind directions, and a dynamic response of structures due to blast loads depends on the load profile. Therefore, a parametric study has to be conducted to investigate the effects of the dynamic response of structural members subjected to various types of load shapes. To do so, a series of CFD analyses was performed using a full-scale FPSO topside model including detail parts of pipes and equipments, and the time history data of the blast loads at monitor points and panels were obtained by the analyses. In this paper, we focus on a structural dynamic response subjected to blast loads changing the magnitude of positive/negative phase pressure and time duration. From the results of linear/nonlinear transient analyses using single degree of freedom(SDOF) and multi-degree-of freedom(MDOF) systems, it was observed that dynamic responses of structures were significantly influenced by the magnitude of positive and negative phase pressures and negative time duration.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4B
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• pp.361-368
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• 2003

An SNMP manager requests a value in MIB of a designated object to an agent by management policy defined in the SNMP, and then the agent responds to this manager. So, it causes a lot of networks traffic between them, Specially, repetitious occurrence of sending-receiving information related to the same object is very inefficient when the trend analysis of traffic is performed. In this paper, an efficient SNMP is proposed to add new PDUs to the existing SNMP in order to accept time function. Utilizing this PDU, it minimizes unnecessary sending-receiving information and collects information on trend management appropriately. The implemented SNMP is tested for compatibility with the existing SNMP and decreases the amount of network traffic greatly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.236-243
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• 2018

The purpose of this study was to investigate the mediating effects of parental attachment and ego resiliency in the tendency toward social networking site (SNS) addiction in college students. For this purpose, 382 college students in the Jeju area were surveyed and their responses analyzed. To analyze the collected data, structural equations were implemented using SPSS Statistics version 18.0. According to the results of the study, there is a significant negative correlation between attachment formation and SNS intoxication in college students, and a negative correlation between ego resiliency and SNS addiction. Also, there is a significant positive correlation between formation of parental attachment and ego resiliency in college students, indicating that parental attachment and ego resiliency are significant factors in lowering SNS addiction. Second, in order to examine the mediating effects of ego resiliency in the relationship between the formation of parental attachment and SNS addiction in college students, a research model and a competition model were established and verified. As a result, the relationship between parent attachment and SNS addiction was mediated completely, and the research model is more appropriate. These findings suggest that ego resiliency is of practical significance in seeking ways to improve the problem of SNS addiction in the future. In other words, overuse of SNSs by university students can lead to addiction, but strengthening ego resiliency enables sound SNS use.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.25-32
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• 2006

Behavior of concrete pavement due to temperature gradient was investigated for 48 hours at test road using Falling Weight Deflectometer. The deflections at slab center changed similarly to those of ambient temperature and temperature gradients in the slab. And rapid variations in the deflections were observed between 8 to 12 in the morning. However, dynamic modulus of subgrade reaction and joint deflections showed reverse trends to the ambient temperature and temperature gradients. The dynamic modulus of subgrade reaction was significantly affected by temperature gradient when its value got higher. Backcalculated elastic moduli were obtained using AREA method and Method of Equivalent Thickness. The trends of the backcalculated elastic modulus were similar to those of dynamic modulus of subgrade reaction. Measured load transfer efficiencies showed maximum peak in the morning due to dowel locking. However, additional effort is necessary to verify the result.

• Journal of Korea Multimedia Society
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• v.10 no.8
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• pp.1017-1028
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• 2007

In this paper we propose an effective method to represent, store, and retrieve video streams efficiently from a video database. We extract features from each video frame, normalize the feature values, and represent them as values in the range [0,1]. In this way a video frame with f features can be represented by a point in the f-dimensional space $[0,1]^f$, and thus the video stream is represented by a trail of points in the multidimensional space. The video stream is partitioned into video segments based on camera shots, each of which is represented by a trend vector which encapsulates the moving trend of points in a segment. The video stream query is processed depending on the comparison of those trend vectors. We examine our method using a collection of video streams that are composed of sports, news, documentary, and educational videos. Experimental results show that our trend vector representation reduces a reconstruction error remarkably (average 37%) and the retrieval using a trend vector achieves the high precision (average 2.1 times) while maintaining the similar response time and recall rate as existing methods.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.474-480
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• 2017

In this study, the evolution of electrical impedance of electric nodes was investigated to determine the setting time of cement paste using the electrical impedance spectroscopy method. The electric nodes were embedded in fresh cement paste and the electrical impedance signatures were continuously monitored. Vicat needle test and semi-adiabatic calorimetry test were also conducted to validate the electrical impedance spectroscopy method. During hydration period of cement paste, the magnitude of conductance gradually increased, and then started to decrease rapidly at a first certain time. After that, the magnitude of conductance gradually decreased at a second certain time. The times of turning point in the curves of magnitude of conductance seem to be related with the setting time by Vicat needle test. Also, the setting times by the electrical impedance spectroscopy method are well posed within the setting period estimated by the semi-adiabatic calorimetry test. Based on the results, it can be concluded that the setting time of cement paste can be effectively monitored through the electrical impedance spectroscopy method.