• Economic and Environmental Geology
• /
• v.28 no.1
• /
• pp.79-88
• /
• 1995

The gravity measurment has been carried out at 48 gravity stations with intervals of 1.0~1.5 km along the survey line between Samcheog, Gosari and Taebaek to study subsurface geology and geologic structure in the northeastern part of the Ockchon zone. The Bouguer gravity anomaly values were obtained from the measured gravity values through the gravity corrections. The subsurface geology and geologic structure were interpreted quantitatively by means of the Fourier series method and Talwani method for 2.5 dimensional body. In the study area, the depth of Conrad discontinuity is about 10 km at Samcheog, northeastern end of the survey line, and it is increased rapidly to about 12.5 km at Miro, 15 km at Gosari and 15.5 km at Dongjeom, southwestern end of the survey line, respectively. The depth of the basement of the Ockchon zone exposed at Samcheog is increased smoothly to about 2 km at 5 km from Samcheog along the survey line, and is exposed again in the area between Singiry and Gosari. Beyond Gosari its depth is increased to about 1.7 km, and displaced 2.3 km downward by Osipcheon fault near Dogyeri and 0.5 km by Baeksan thrust near Cheolam, respectively. Many V-shaped low Bouguer gravity anomalies resulted from the fracture zone associated with faults imply the existence of Osipcheon fault and several inferred faults. The low Bouguer gravity anomaly zone between Tongdong and Dongjeom is caused by Jurassic gneissose granite. A local high Bouguer gravity anomaly at 35 km along the survey line from Samcheog is interpreted by the effect of iron deposit of high density existed at subsurface. The thickness of Great Limestone Group varies from 0.5 km to 1.4 km, that of Pyeongan Supergroup from 0.4 km to 0.9 km, and that of Yangdeog Group is about 0.3 km. The thickness of Jurassic gneissose granite varies from 1.5 to 3.0 km.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.30 no.5
• /
• pp.444-450
• /
• 2010

In the present study, the microscopic degradation of copper and copper alloy subjected to cyclic deformation has been evaluated by the electrical resistivity measurement using the DC four terminal potential method. The copper (Cu) and copper alloy (Cu-35Zn), whose stacking fault energy is much different each other, were cyclically deformed to investigate the response of the electrical resistivity to different dislocation substructures. Dislocation cell substructure was developed in the Cu, while the planar array of dislocation structure was developed in the Cu-35Zn alloy increasing dislocation density with fatigue cycles. The electrical resistivity increased rapidly in the initial stage of fatigue deformation in both materials. Moreover, after the fatigue test it increased by about 7 % for the Cu and 6.5 % for the Cu-35Zn alloy, respectively. From these consistent results, it may be concluded that the dislocation cell structure responds to the electrical resistivity more sensitively than the planar array dislocation structure evolved during cyclic fatigue.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.1225-1234
• /
• 2009

As the Wenchuan Earthquake was of high magnitude and shallow seismic focus, it caused great damage and serious geo-hazards. By the field investigation and remote-sensing interpretation after the earthquake and by using means of GIS, the distribution of geo-hazards triggered by the earthquake was analyzed and the conclusions are as follows: (1) the earthquake geo-hazards showed the feature of zonal distribution along the earthquake fault zone and linear distribution along the rivers; (2) the distribution of earthquake geo-hazards had a marked hanging wall effect, for the development density of geo-hazards in the hanging wall of earthquake fault was obviously higher than that in the foot wall and the width of strong development zone in the hanging wall was about 10 km; (3) the topographical slope was a main factor which controlled the development of earthquake geo-hazards and a vast majority of geo-hazards were distributed on the slopes of 20 to 50 degrees; (4) the earthquake geo-hazards had a corresponding relationship with the elevation and micro-landform, for most hazards happened in the river valleys and canyon sections below the elevation of 1500 to 2000 m, particularly in the upper segment of canyon sections (namely, the turning point from the dale to the canyon). Thin ridge, isolated or full-face space mountains were most sensitive to the seismic wave, and had a striking amplifying effect. In these areas, collapses and landslides were most likely to develop; (5) the study also showed that different lithologies determined the types of geo-hazards, and usually, landslides occurred in soft rocks, while collapses occurred in hard rocks.

• Progress in Superconductivity and Cryogenics
• /
• v.17 no.1
• /
• pp.10-13
• /
• 2015

High-temperature superconducting coated conductors (HTS-CCs) are good candidates for resistive superconducting fault current limiter (RSFCL) applications. However, the high current density they can carry and their low thermal diffusivity expose them to the risk of thermal instability. In order to find the best compromise between stability and cost, it is important to study the heat transfer between HTS-CCs and the liquid nitrogen ($LN_2$) bath. This paper presents an experimental method to monitor in real-time the temperature of a quenched HTS-CC during a current pulse. The current and the associated voltage are measured, giving a precise knowledge of the amount of energy dissipated in the tape. These values are compared with an adiabatic numerical thermal model which takes into account heat capacity temperature dependence of the stabilizer and substrate. The result is a precise estimation of the heat transfer to the liquid nitrogen bath at each time step. Measurements were taken on a bare tape and have been repeated using increasing $Kapton^{(R)}$ insulation layers. The different heat exchange regimes can be clearly identified. This experimental method enables us to characterize the recooling process after a quench. Finally, suggestions are done to reduce the temperature increase of the tape, at a rated current and given limitation time, using different thermal insulation thicknesses.

• Journal of KIISE:Software and Applications
• /
• v.26 no.11
• /
• pp.1282-1287
• /
• 1999

통신 프로그램은 고도의 신뢰성과 기능성, 확장성, 그리고 유지 보수성이 필요하다. 프로그램 테스트의 결과와 McCabe의 Complexity를 측정한 데이타를 가지고 회귀모델을 만들고 그 신뢰성을 분석함으로서 프로그램의 결함과 복잡도의 관련성을 평가한다.본 연구에서 사용한 통신 프로그램은 500개 블록이 59가지 기능을 수행하는 교환 기능 중에서 복잡도가 너무 많아서 통계 처리의 bias가 될 블록을 제외하고 394 블록을 선정하여 SAS에 의해서 통계 분석을 하고 회귀 분석 모델을 설계하였다. t 분포에 의하여 방정식의 유의성 수준을 검증하고 프로그램의 결함수에 가장 큰 영향을 주고 있는 복잡도가 McCabe의 복잡도와 설계 복잡도 임을 밝혀냈다. 이 연구 결과에 의해서 설계 정보 및 유지 보수 정보를 얻을 수 있다. Abstract Switching software requires high reliability, functionality, extendability and maintainability. For doing, software quality model based on MaCabe's complexity measure is investigated. It is experimentally shown using regression analysis the program fault density depends on the complexity and size of the function unit. The software should be verified and tested if it satisfies its requirements with automated analysis tools. In this paper we propose the regression model with the test data.The sample program for the regression model consists of more than 500 blocks, where each block compose of 10 files, which has 59 functions of switching activity.Among them we choose 394 blocks and analyzed for 59 functions by testing tools and SAS package. We developed Regression Analysis Model and evaluated significant of the equation based on McCabe's cyclomatic complexity, block design complexity, design complexity, and integration complexity.The results of our experimental study are that number of fault are under the influence of McCabe's complexity number and design complexity.

• Smart Structures and Systems
• /
• v.29 no.1
• /
• pp.181-193
• /
• 2022

Data-driven structural health monitoring (SHM) of civil infrastructure can be used to continuously assess the state of a structure, allowing preemptive safety measures to be carried out. Long-term monitoring of large-scale civil infrastructure often involves data-collection using a network of numerous sensors of various types. Malfunctioning sensors in the network are common, which can disrupt the condition assessment and even lead to false-negative indications of damage. The overwhelming size of the data collected renders manual approaches to ensure data quality intractable. The task of detecting and classifying an anomaly in the raw data is non-trivial. We propose an approach to automate this task, improving upon the previously developed technique of image-based pre-processing on one-dimensional (1D) data by enriching the features of the neural network input data with multiple channels. In particular, feature engineering is employed to convert the measured time histories into a 3-channel image comprised of (i) the time history, (ii) the spectrogram, and (iii) the probability density function representation of the signal. To demonstrate this approach, a CNN model is designed and trained on a dataset consisting of acceleration records of sensors installed on a long-span bridge, with the goal of fault detection and classification. The effect of imbalance in anomaly patterns observed is studied to better account for unseen test cases. The proposed framework achieves high overall accuracy and recall even when tested on an unseen dataset that is much larger than the samples used for training, offering a viable solution for implementation on full-scale structures where limited labeled-training data is available.

• Geophysics and Geophysical Exploration
• /
• v.11 no.2
• /
• pp.99-108
• /
• 2008

To extend our detailed knowledge for the Hwasan caldera, we carried out magnetotelluric (MT) survey, which is pretty sensitive to electrical property variation in both horizontal and vertical direction of subsurface, across the Hwasan caldera with the direction of EW. The 2-D inversion results of observed MT data lead to following conclusions. Firstly, the depth of the basin basement inferred by the MT inversion results matches well with that suggested by previous potential studies, but the basement resistivity seems fairly low when compared to that of general case. This feature might be related with the large-scaled, highly conductive layer beneath the Euisung Sub-basin suggested by the previous MT study. Secondly, the high resistivity zones reaching to 4000 $\Omega{\cdot}m$ are imaged around two external ring fault boundaries. These zones are thought of as the response of the rhyolitic dykes intruding along the ring fault, and in the previous gravity data correspond to relatively high density anomalies. Thirdly, low resistivity zone reaching to 200 $\Omega{\cdot}m$ is detected around a depth of 1km beneath the central part of the caldera, which has not been yet reported in korean geophysical literatures. If we take account of the evolution model of the Hwasan caldera, this zone is regarded as the past sedimentary layer that subsided during the period of forming external ring fault system. In addition, the relatively low density anomaly observed in the central part of the caldera may be attributed to this sedimentary layer.

• Economic and Environmental Geology
• /
• v.52 no.6
• /
• pp.573-586
• /
• 2019

A seismic hazard map based on spatial analysis of various sources of geologic seismic information was developed and assessed for regional seismic vulnerability in South Korea. The indicators for assessment were selected in consideration of the geological characteristics affecting the seismic damage. Probabilistic seismic hazard and fault information were used to be associated with the seismic activity hazard and bedrock depth related with the seismic damage hazard was also included. Each indicator was constructed of spatial information using GIS and geostatistical techniques such as ordinary kriging, line density mapping and simple kriging with local varying means. Three spatial information constructed were integrated by assigning weights according to the research purpose, data resolution and accuracy. In the case of probabilistic seismic hazard and fault line density, since the data uncertainty was relatively high, only the trend was intended to be reflected firstly. Finally, the seismic activity hazard was calculated and then integrated with the bedrock depth distribution as seismic damage hazard indicator. As a result, a seismic hazard map was proposed based on the analysis of three spatial data and the southeast and northwest regions of South Korea were assessed as having high seismic hazard. The results of this study are expected to be used as basic data for constructing seismic risk management systems to minimize earthquake disasters.

• Spatial Information Research
• /
• v.10 no.2
• /
• pp.247-261
• /
• 2002

There are much damage of people and property because of heavy rain every year. Especially, there are problem to major facility such as dam, bridge, road, tunnel, and industrial complex in the ground stability. So the counter plan for landslide or ground failure must be necessary In the study, the technique of regional landslide susceptibility assessment near the Ulsan petrochemical complex and Kumgang railway bridge was developed and applied using GIS. For the assessment, the geological structures such as bedding and fault were surveyed and the geological structure, topographic, soil, forest, and land use spatial database were constructed using CIS. Using the spatial database, the factors that influence landslide occurrence, such as slope, aspect, curvature and type of topography, texture, material, drainage and effective thickness of soil, type, age, diameter and density of forest, and land use were calculated or extracted from the spatial database. For application of geological structure, the geological structure line and fault density were calculated. Landslide susceptibility was analyzed using the landslide-occurrence factors by probability method that is summation of landslide occurrence probability values per each factors range or type. The landslide susceptibility map can be used to assess ground stability to protect major facility.

• The Journal of Engineering Geology
• /
• v.29 no.1
• /
• pp.1-12
• /
• 2019

Earthquake can change underground stress condition around the hypocenter and affect the fracture systems of the rocks. In Korea, the M5.8 Gyeongju earthquake on September 12, 2016 and M5.4 Pohang earthquake on November 15, 2017 occurred inside the Yangsan fault zone and possibly affected the fracture systems in the Yangsan fault zone and nearby rock masses. In this study, the characteristics of the fracture system (fracture orientation, number of the fractures, fracture spacing and aperture, dip angle, fracture density along depth, and relative rock strength) of the rocks in the low/intermediate level radioactive waste repository site located in the coastal area of the East Sea are analyzed by the impact of the Gyeongju and Pohang earthquakes using acoustic televiewer data taken from the boreholes at the radioactive waste repository site in 2005 and 2018. As a result of acoustic televiewer logging analysis, the fracture numbers, fracture aperture, and fracture density along depth overall increased in 2018 comparing to those in 2005. This increase tendency may be due to changes in the fracture system due to the impact of the earthquakes, or due to weathering of the wall of the boreholes for a long period longer than 10 years after the installation of the boreholes in 2005. In the borehole KB-14, on the whole, the orientation of the fractures and the average fracture spacing are slightly different between 2005 and 2018, while dip angle and relative rock strength in 2005 and 2018 are similar each other.