• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1125-1132
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• 2009

The theory and a probe of the pilot hole wall deformation method, which is a 3-dimensional stress measurement method based on the stress relief principle, were developed. A pilot hole is drilled from the bottom of a borehole and the stress measurement probe is inserted into the pilot hole. The borehole is advanced as the overcoring and the changes in the radius of the pilot hole in three directions and in the axial lengths between the borehole bottom and the pilot hole wall along four axial lines are measured by cantilever type-displacement sensors. The differences between the displacements by the elastic stress analysis and those measured by using the probe were within 3% in the uniaxial compression test of an acrylic resin plate having a hole.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.6
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• pp.583-590
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• 2015

Automobile crash optimization is nonlinear dynamic response structural optimization that uses highly nonlinear crash analysis in the time domain. The equivalent static loads (ESLs) method has been proposed to solve such problems. The ESLs are the static load sets generating the same displacement field as that of nonlinear dynamic analysis. Linear static response structural optimization is employed with the ESLs as multiple loading conditions. Nonlinear dynamic analysis and linear static structural optimization are repeated until the convergence criteria are satisfied. Nonlinear dynamic crash analysis for frontal analysis may not have boundary conditions, but boundary conditions are required in linear static response optimization. This study proposes a method to use the inertia relief method to overcome the mismatch. An optimization problem is formulated for the design of an automobile frontal structure and solved by the proposed method.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.5
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• pp.389-395
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• 2019

Unlike aerial images covering small region, satellite data show high potential to detect urban scale geospatial changes. The change detection using satellite images can be carried out using single image or stereo images. The single image approach is based on radiometric differences between two images of different times. It has limitations to detect building level changes when the significant occlusion and relief displacement appear in the images. In contrast, stereo satellite data can be used to generate DSM (Digital Surface Model) that contain information of relief-corrected objects. Therefore, they have high potential for the object change detection. Therefore, we carried out a study for the change detection over an urban area using stereo satellite data of two different times. First, the RPC correction was performed for two DSMs generation via stereo image matching. Then, D-DSM (Differential DSM) was generated by differentiating two DSMs. The D-DSM was used for the topographic change detection and the performance was checked by applying different height thresholds to D-DSM.

• Geosystem Engineering
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• v.21 no.6
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• pp.318-325
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• 2018

Eight tight sandstone reservoir samples from $He_8$ and $Shan_1$ Formations of the Sulige Gas field were selected to perform gas-water micro-displacement experiment based on authentic sandstone micro-model. The gas pressure-relief experiment was proposed for the first time to simulate the pressure change and gas-water percolation characteristics in the process of gas exploitation. The experiment results show that: (1) In the process of gas accumulation, the gas preferentially flows into the well-connected pores and throats with large radius, but rarely flows into the area without pores and throats. (2) Under sufficient gas drive, the water in pores and throats usually exists in the forms of 'thin water film', 'thick water film', and 'water column', but under insufficient gas drive, gas fails to flow into new pathways in time, so that the reservoirs with large pores and throats are high in water cut. (3) Under the same water saturation, the reservoirs with better petrophysical properties has higher gas recovery factor within unit time. Under the same petrophysical conditions, the reservoirs with lower water saturation show higher gas recovery factor within unit time. The higher the permeability, the stronger the liquid carrying capacity of reservoirs.

• The Korean Journal of Pain
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• v.34 no.3
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• pp.346-368
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• 2021

Background: Recalcitrant disc herniation may result in chronic lumbar radiculopathy or sciatica. Fluoroscopically directed epidural injections and other conservative modalities may provide inadequate improvement in some patients. In these cases, percutaneous neurolysis with targeted delivery of medications is often the next step in pain management. Methods: An evidence-based system of methodologic assessment, namely, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was used. Multiple databases were searched from 1966 to January 2021. Principles of the best evidence synthesis were incorporated into qualitative evidence synthesis. The primary outcome measure was the proportion of patients with significant pain relief and functional improvement (≥ 50%). Duration of relief was categorized as short-term (< 6 months) and long-term (≥ 6 months). Results: This assessment identified one high-quality randomized controlled trial (RCT) and 5 moderate-quality non-randomized studies with an application of percutaneous neurolysis in disc herniation. Overall, the results were positive, with level II evidence. Conclusions: Based on the present systematic review, with one RCT and 5 non-randomized studies, the evidence level is II for percutaneous neurolysis in managing lumbar disc herniation.

• Advances in environmental research
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• v.10 no.1
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• pp.1-15
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• 2021

Rising urban flood patterns are a universal phenomenon and a significant challenge for city government and urban planners worldwide. Urban flood problems range from relatively localized incidents to substantial incidents, which lead to cities being flooded for a few hours to several days. Therefore, the effect may be widespread, such as the temporary displacement of individuals, disruption to civic facilities, water quality degradation and the possibility of epidemics. The problems raised by urban flooding are highly challengeable and compound by ongoing climate change, with adverse implications for changes in rainfall and gaps in intra-urban rainfall distribution. Unplanned construction and invasions of large houses along rivers and watercourses have interfered in natural rivers and watercourses. As a result, the runoff has risen in proportion to the urbanization of the urban floods. The location of the relief camp and the priority for evacuation were determined, and the safest route to avoid floods were established. This method can be used for emergency planning in future flood incidents, and it will help plan disaster preparedness for Panchayat. This study will promote the flood plain's potential use for disaster management and land use planning virtually.

• Geomechanics and Engineering
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• v.39 no.1
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• pp.87-104
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• 2024

In practical engineering, the design process for most retaining walls necessitates careful consideration of seismic resistance. The prevention of retaining wall overturning is of paramount importance, especially in cases where the foundation's bearing capacity is limited. To research the seismic active earth pressure (ES) of a relieving retaining wall rotating around base (RB), the shear dissipation graphs across various operating conditions are analyzed by using Optum software, and the earth pressure in each region was derived by the inclined strip method combined with the limit equilibrium method. By observing shear dissipation graphs across various operating conditions, the distribution law of each sliding surface is summarized, and three typical failure modes are obtained. The corresponding calculation model was established. Then the resultant force and its action point were obtained. By comparing the theoretical and numerical solutions with the previous studies, the correctness of the derived formula is proved. The variation of earth pressure distribution and resultant force under seismic acceleration are studied. The unloading plate's position, the wall heel's length, and seismic acceleration will weaken the unloading effect. On the contrary, the length of the unloading plate and the friction angle of the filling will strengthen the unloading effect. The derived formula proposed in this study demonstrates a remarkable level of accuracy under both static and seismic loading conditions. Additionally, it serves as a valuable design reference for the prevention of overturning in relieving retaining walls.

• Fire Science and Engineering
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• v.30 no.1
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• pp.104-110
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• 2016

Positive displacement pumps with high pressure and water capacity are used large fires in various high-rise buildings. This study provides information for a performance approval standard of fire pumps for fire trucks based on centrifugal pump standards enacted in 2012. An experiment was conducted with a positive displacement pump for three levels of performance from the approval standard (V-1, 2, and 3). The efficiency of the pump was included in the reference, which requires the approval of 65% performance, the same as a centrifugal pump. The water pressure is between 1.5 and 2.5 MPa, and the required flow rate was established as at least $0.31m^3/min$ and up to $3.0m^3/min$. A relief valve was added to adjust the shut-off pressure due to the structural characteristics of the positive displacement pump. A strainer was also installed to prevent damage to the inside of the pump due to foreign matter. However, the strainer includes a difference from the positive displacement pump to operate without a vacuum pump and the centrifugal pump. This is due to the additional approval standard portion of the positive displacement pump, which is expected to be selected for more variety of fire-fighting equipment and proactive responses to fire suppression in a high-rise buildings and large fires. In conclusion, this approval standard was enacted in January 2016.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.299-302
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• 2004

최근에 상용화되어 있는 영상 중 가장 고해상도인 ikonos 영상은 공간해상도가 높기 때문에 더 많은 지형지물 정보를 포함하고 있다. 그러나 이러한 커다란 장점과 더불어 고층건물이나 높은 표고의 지형에서 발생하는 기복변위 보정이라는 소축척 영상에서 볼 수 없었던 새로운 문제가 등장하였다. 특히, 이러한 고해상도 영상들은 산악지역에서 식생에 대한 세밀한 정보를 제공하지만 상대적으로 높은 고도를 가지고 있기 때문에 발생하는 기복왜곡과 그림자 효과가 자료의 이용에 제한요인으로 작용하게 된다. 본 연구에서는 ikonos 고유의 센서정보와 수치지형도를 통하여 획득한 DEM(수치표고모델)을 이용하여 정밀편위보정방법(Difference rectification method) 방법에 의해 기하보정을 수행하고 그 결과 발생하는 산악지역에서는 기복변위를 분석하였다.

• Korean Journal of Bronchoesophagology
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• v.10 no.2
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• pp.5-8
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• 2004

Stenosing airway disease is classified as intraluminal obstruction, extrinsic compression, and malacia by the anatomical site of the lesion. Stenting therapy is indicated for symptomatic relief of life-threatening dyspnea caused by the last two types. Airway stents are made with metal mesh and/or silicone rubber, and currently more than 20 kinds of stent are available. Among many kinds of silicone stent, the Dumon stent is mostly widely used for benign and malignant airway stenoses, but general anesthesia and rigid bronchoscopy are needed for insertion. It can be removed when the stenosing airway disease subsides completely. In many clinical studies, most patients $(85-90\%)$ improved immediately after stenting, and procedure-related mortality was low $(<3\%)$ in experienced centers. Stent displacement, mucus impaction, and granulation tissue formation are potential complications. Stenting is one of many effective therapeutic modalities for stenosing central airway disease. Careful patient selection, experiences, and continuous development of new technology will bring better results.