• Land and Housing Review
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• v.14 no.3
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• pp.125-135
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• 2023

In South Korea, it has been increased the necessity of supplying housing services to meet the needs and desires of various residents by reflecting various demographic and social changes. In particular, various smart device has been widely utilized in South Korea and the smart technologies, such as artificial intelligence and the Internet of Things has been developed rapidly. These smart technologies could support smart housing that allows residents to easily and comfortably employ residential services. However, it is necessary to improve the awareness of users in order to spread the smart housing residential services connected to smart technologies. For this reason, this study observed changes in users' perceptions of smart housing residential service technology using Living Lab. As a result, after experiencing the Living Lab, users' awareness of smart housing housing service increased, and it was observed that the preferred housing service technology was more detailed than before the Living Lab experience. This study shows that it is important to raise users' awareness for the dissemination of smart housing residential service technology, and that Living Lab can be an effective means for this purpose.

• Land and Housing Review
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• v.14 no.3
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• pp.55-75
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• 2023

Based on prior studies on real estate policy, tax policy, and financial policy, this study examined how tax policy and financial policy affected real estate prices using monthly data from January 2014 to December 2021. We performed a VAR model using unit root tests, cointegration tests, as well as conducted impulse response analysis and variance decomposition analysis. The results are as follows. First, the tax regulation index and the financial regulation index had no discernible impact on housing prices. Specifically, a one-sided stabilizing regulatory policy was ineffective and, instead, led to unintended side effects, such as price increases resulting from reduced transaction volume. Secondly, mortgage rates had a negative impact on the housing sale price index. In other words, an increase in interest rates might led to a decrease in housing prices. Thirdly, an increase in the transfer difference, which involves capital gains tax, has a positive effect on housing prices. This led to rising housing prices because the transfer taxes were shifted to buyers, causing them to hesitate to make purchases due to the increased tax burden. Fourthly, both acquisition taxes and mortgage loans had relatively little impact on housing prices.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.101-120
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• 2023

Electrical resistivity survey have been widely conducted at diverse scales, from a few centimeters for laboratory tests to kilometers for field tests. It measures electrical resistance through relationship of electric potential difference and current between two electrodes penetrated on the surface of medium, and eventually quantifies electrical resistivity known as inherent properties of the medium. In field or full-scale test, it assumes the electrodes as equivalent half-sphere electrodes that have a same surface area with different electrodes for ease of calculation because the contact area between electrode and medium is small and sufficient distance between two electrodes. However, small-scale laboratory test is significantly affected by the electrode geometries (penetrated depth, height, radius of electrode and distance between electrodes), which change the equipotential surface and electric current flow. Indeed, the electrode geometries may eventually cause a difference of electrical resistivity value. This study reviews the theoretical electrical resistance derived with various electrode geometries (half-sphere, cylinder, cylindrical with half-spherical tip, cylindrical with conical tip) and verifies the developed numerical module by comparing results with the theoretical electrical resistance. The distributions of electrical resistance around electrodes and among electrodes are analyzed. In addition, it is discussed how the electrical characteristic of cylindrical electrode with conical tip widely used in field test has effect on the electric current flow.

• Journal of the Korean Geosynthetics Society
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• v.22 no.1
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• pp.87-96
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• 2023

There are a lot of difference between the surface settlement and the differential settlement measured at the Busan New Port, where the dredged and reclaimed clay layer exists and below the clay is originally thickly distributed. To find the cause and solution of this, the actual conditions of each differential settlement used for the soft ground improvement, characteristics, installation method, measurement frequency, measurement data management, and data analysis of each type were considered. In the deep soft ground improvement work where large deformation occurs, the bending deformation of the screw-type differential settlement gauge is less than that of other types of measuring instruments, so there is less risk of loss, and the reliability of data is relatively high as the instruments are installed by drilling for each stratum. Since the greater the amount of high-precision settlement measurement data, the higher the settlement analysis precision. It is necessary to manage with higher criteria than the measurement frequency suggested in the standard specification. For the data management of the differential settlement gauge, it is desirable to create graphs of the settlement and embankment height of the relevant section over time, such as surface, differential, and settlement of pore water pressure gauge for each point. In the case of multi-layered ground with different compression characteristics, it is more appropriate to perform settlement analysis by calculating the consolidation characteristics of each stratum using a differential settlement data.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.17-30
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• 2009

Underground construction such as tunneling can induce damages on the surrounding rock mass, due to the stress concentration of in situ stresses and excessive energy input during construction sequence, such as blasting. The developed damage on the rock mass can have substantial influence on the mechanical and hydraulic behaviors of the rock masses around a tunnel. In this study, investigation on the generation of damage around an opening in a jointed rock model under biaxial compression condition was conducted. The joint dip angles employed are 30, 45, and 60 degrees to the horizontal, and the synthetic rock mass was made using early strength cement and water. From the biaxial compression test, initiation and propagation of tensile cracks at norm to the joint angle were found. The propagated tensile cracks eventually developed rock blocks, which were dislodged from the rock mass. Furthermore, the propagation process of the tensile cracks varies with joint angle: lower joint angle model shows more stable and progressive tensile crack propagation. The development of the tensile crack can be explained under the hypothesis that the rock segment encompassed by the joint set is subjected to the developing moment, which can be induced by the geometric irregularity around the opening in the rock model. The experiment results were simulated by using discrete element method PFC 2D. From the simulation, as has been observed from the test, a rock mass with lower joint angle produces wider damage region and rock block by tensile cracks. In addition, a rock model with lower joint angle shows progressive tensile cracks generation around the opening from the investigation of the interacted tensile cracks.

• Journal of the Korean Geotechnical Society
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• v.23 no.7
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• pp.57-64
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• 2007

This study proposes a method to estimate drilling torque during ground boring with an aid of electrical energy required for rotating a boring-auger. Ground boring is commonly used in geotechnical engineering such as preboring precast pile installation, soil-cement grouting, ground exploration and so forth. In order to understand the correlation between required electrical energy to rotate the boring auger and the drilling torque, a small laboratory apparatus was designed and a pilot study was performed. The apparatus rotates common drill bits of $D=5{\sim}25mm$ in CBR specimens. The velocity of a bit is 19 RPM and predefined using a reduction gear which connects a main rotation axis to a 25 Watts AC electrical motor shaft. In the middle of drilling the motor current increments and the drilling torque were measured and the correlation between the current and the torque was obtained through linear square fits. Based on the correlation the acquired motor current during drilling was applied to predict the drilling torque in consequent testing and the prediction results were compared to the measured torque. The comparison leads a conclusion that the motor current during drilling using electrical power may be a good indicator to estimate/determine strength characteristics of the ground.

• Journal of the Korean Geotechnical Society
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• v.39 no.5
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• pp.27-40
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• 2023

A pile is a structural element that is used to transfer external loads from superstructures and has been widely utilized in construction fields all over the world. The method of installing a pile into the ground should be selected based on geotechnical conditions, location, site status, environmental factors, and construction costs, among others. It can be divided into two types: direct hammering and preboring. The direct hammering method installs a pile into the bearing layer, such as rock, using a few types of hammer, generating a considerable amount of pile driving-induced vibration. The vibration from pile driving influences adjacent structures and the ground; therefore, quantitatively investigating the effects of vibration is inevitably required. In this study, two-dimensional dynamic numerical modeling and analysis are performed using the finite difference method to investigate the influence on the adjacent slope, including temporary supporting system. Time-dependent loading induced by pile driving is estimated and used in the numerical analysis. Consequently, large surface displacement is estimated due to surface waves and less wave deflection, and refraction at the surface. The total displacement decreases with the increase of the distance from the source. However, lateral displacement at the top of the slope shows a larger value than vertical displacement, and the overall displacement tends to be concentrated near the face of the slope.

• Journal of Korea Water Resources Association
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• v.56 no.4
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• pp.245-259
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• 2023

The agricultural reservoir is a critical water supply system in South Korea, providing approximately 60% of the agricultural water demand. However, the reservoir faces several issues that jeopardize its efficient operation and management. To address this issues, we propose a novel deep-learning-based water level recognition model that uses CCTV image data to accurately estimate water levels in agricultural reservoirs. The model consists of three main parts: (1) dataset construction, (2) image segmentation using the U-Net algorithm, and (3) CCTV-based water level recognition using either CNN or ResNet. The model has been applied to two reservoirs G-reservoir and M-reservoir with observed CCTV image and water level time series data. The results show that the performance of the image segmentation model is superior, while the performance of the water level recognition model varies from 50 to 80% depending on water level classification criteria (i.e., classification guideline) and complexity of image data (i.e., variability of the image pixels). The performance of the model can be improved if more numbers of data can be collected.

• Journal of Cadastre & Land InformatiX
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• v.52 no.2
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• pp.189-210
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• 2022

Cities around the world have paid attention to public transportation as an alternative to reducing traffic congestion caused by automobile usage, excessive energy consumption, and environmental pollution. This study measures accessibility to subway stations in Seoul using a supply-demand-based accessibility technique. Then, the impacts were analyzed through land prices by use and segment. As a result of analysis using the multilevel hedonic price models, accessibility considering both supply and demand for the subway had a positive effect on both residential and non-residential land prices. The effect was stronger for residential than for non-residential. Further, among the accessibility measured by the three functions, the accessibility by the Exponential function was most suitable for the residential land price, and the accessibility measured by the Power function for the non-residential land price had the highest explanatory power. Also, looking at the impacts by land price segments, it was found that higher access to metro stations had the greatest positive impacts on the most expensive segment of residential and non-residential land prices. The results of this study can be applied not only to identify the impacts of public investment on neighborhoods, but also to support real estate valuation.

• Journal of Cadastre & Land InformatiX
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• v.53 no.1
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• pp.47-63
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• 2023

The Seoul Metropolitan Government is building and operating digital twin-based urban spatial information to solve various problems in the city and provide public services. Two essential factors to ensure the stable utilization of spatial information for the implementation of such a digital twin city are the latest and quality of the data. However, it is time-consuming and costly to maintain continuous updating of high-quality urban spatial information. To overcome this problem, we studied efficient urban spatial information construction technology and the operation, management, and update procedures of construction data. First, we demonstrated and applied automatic 3D building construction technology centered on point clouds using the latest hybrid sensors, confirmed that it is possible to automatically construct high-quality building models using high-density airborne lidar results, and established an efficient data management plan. By applying differentiated production methods by region, supporting detection of urban change areas through Seoul spatial feature identifiers, and producing international standard data by level, we strengthened the utilization of urban spatial information. We believe that this study can serve as a good precedent for local governments and related organizations that are considering activating urban spatial information based on digital twins, and we expect that discussions on the construction and management of spatial information as infrastructure information for city-level digital twin implementation will continue.