• Journal of the Korean Geotechnical Society
• /
• v.37 no.9
• /
• pp.13-24
• /
• 2021

Recently, attempts have been made to detect fouling patterns in the ground using Ground Penetrating Radar (GPR) during the maintenance of gravel ballast railway tracks. However, dealing with GPR signal data obtained with a large amount of noise in a site where complex ground conditions are mixed, often depends on the experience of experts, and there are many difficulties in precise analysis. Therefore, in this study, a numerical modeling technique that can quantitatively simulate the GPR signal characteristics according to the degree of fouling of the gravel ballast material was proposed using python-based open-source code gprMax and RSA (Random sequential Absorption) algorithm. To confirm the accuracy of the simulation model, model tests were manufactured and the results were compared to each other. In addition, the identification of the fouling layer in the model test and analysis by various test conditions was evaluated and the results were analyzed.

• Korean Journal of Construction Engineering and Management
• /
• v.22 no.5
• /
• pp.17-28
• /
• 2021

The construction industry has challenges and opportunities for Sustainable Development Goals (SDGs). The task of the construction industry is to improve the quality of construction, which is particularly necessary for the Fragile State. The construction industry's primary role is to provide jobs and maintain and improve the construction environment that affects the quality of life. Using the Delphi method and EFA in this study, [Pre-Execution] and [Execution] were derived as risk areas that require intensive hedge when penetrating the construction market in fragile states. It was concluded that the risk hedge to the master plan for the business conditions and infrastructure is the most important.

• Geomechanics and Engineering
• /
• v.23 no.6
• /
• pp.513-521
• /
• 2020

In this paper, due to the need for cutting cement-soil group pile composite foundation under the 7-story masonry structure of Zhenghe District and the shield tunnel of Zhengzhou Metro Line 5, a field test was conducted to directly cut cement-soil single pile composite foundation with diameter Ф=500 mm. Research results showed that the load transfer mechanism of composite foundation was not changed before and after shield tunnel cut the pile, and pile body and the soil between piles was still responsible for overburden load. The construction disturbance of shield cutting pile is a complicated mechanical process. The load carried by the original pile body was affected by the disturbance effect of pile cutting construction. Also, the fraction of the load carried by the original pile body was transferred to the soil between the piles and therefore, the bearing capacity of composite foundation was not decreased. Only the fractions of the load carried by pile and the soil between piles were distributed. On-site monitoring results showed that the settlement of pressure-bearing plates produced during shield cutting stage accounted for about 7% of total settlement. After the completion of pile cutting, the settlements of bearing plates generated by shield machine during residual pile composite foundation stage and shield machine tail were far away from residual pile composite foundation stage which accounted for about 15% and 74% of total settlement, respectively. In order to reduce the impact of shield cutting pile construction on the settlement of upper composite foundation, it was recommended to take measures such as optimization of shield construction parameters, radial grouting reinforcement and "clay shock" grouting within the disturbance range of shield cutting pile construction. Before pile cutting, the pile-soil stress ratio n of composite foundation was 2.437. After the shield cut pile is completed, the soil around the lining structure is gradually consolidated and reshaped, and residual pile composite foundation reaches a new state of force balance. This was because the condensation of grouting layer could increase the resistance of remaining pile end and friction resistance of the side of the pile.

• Journal of Trauma and Injury
• /
• v.34 no.4
• /
• pp.248-256
• /
• 2021

Purpose: Laparoscopy has various advantages over laparotomy in terms of postoperative recovery. The number of surgeons using laparoscopy as a diagnostic and therapeutic tool in abdominal trauma patients is increasing, whereas open conversion is becoming less common. This report summarizes a single surgeon's experience of laparoscopy at a level I trauma center and evaluates the feasibility of laparoscopy as a diagnostic and therapeutic tool for abdominal trauma patients. Methods: In total, 30 abdominal trauma patients underwent laparoscopy by a single surgeon from October 2014 to May 2020. The purpose of laparoscopy was categorized as diagnostic or therapeutic. Patients were classified into three groups by type of surgery: total laparoscopic surgery (TLS), laparoscopy-assisted surgery (LAS), or open conversion (OC). Univariate analysis was performed to determine the advantages and disadvantages. Results: The mechanism of injury was blunt in 19 (63.3%) and penetrating in 11 patients (36.7%). Eleven (36.7%) and 19 patients (63.3%) underwent diagnostic and therapeutic laparoscopy, respectively. The hospital stay was shorter for patients who underwent diagnostic laparoscopy than for those who underwent therapeutic laparoscopy (5.0 days vs. 13.0 days), but no other surgical outcomes differed between the groups. TLS, LAS, and OC were performed in 12 (52.2%), eight (34.8%), and three patients (13.0%), respectively. There was no significant difference in morbidity and mortality among the three groups. Conclusions: Laparoscopic surgery for selected cases of abdominal trauma may be feasible and safe as a diagnostic and therapeutic tool in hemodynamically stable patients due to the low OC rate and the absence of fatal morbidity and mortality.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.40 no.2
• /
• pp.109-118
• /
• 2022

GPR (Ground Penetrating Radar), developed as a technology for geotechnical investigations such as sinkhole exploration, was used limitedly as a method to resolve undetectable lines in underground facility exploration. To improve the accuracy of underground facility data, the government made it possible to explore underground facilities using a non-metallic pipeline probe from July 2022. However, GPR has a problem in that the exploration rate is lowered in the soil with high moisture content, such as soft soil, such as clay layer, and there is a lot of variation in long-term accuracy. In this study, as a way to improve the accuracy of exploration considering the characteristics of GPR and the environment of underground facilities, we propose a GPR exploration method for underground facilities using permittivity constant correction and pattern analysis of GPR image data. Through this study, the accuracy of underground facility exploration and high reproducibility were derived as a result of field verification applying GPR frequency band and heterogeneous GPR.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.11a
• /
• pp.243-244
• /
• 2022

In this paper, experiments were conducted on signal amplification of polymer capsules for application to Ground Penetrating Radar so as to enable real-time monitoring of polymer capsules inside concrete using the Morphology Dependent Resonance phenomenon. A TEM CELL and a vector network analyzer were used to analyze the difference in resonance frequency depending on the material of the sphere and the presence or absence of fracture. In order to manufacture a capsule of a size that can be measured using millimeter waves used in GPR, we manufactured a capsule with a 3D printer and analyzed the effects of the presence or absence of coating and the size of the capsule on the resonance frequency. Resonant frequency or signal amplification is more affected by diameter than coating. The capsule showing the highest amplification is the resin-coated 50 mm diameter capsule with a 316-fold increase and the lowest capsule is the uncoated 10 mm diameter capsule with a signal amplification of 11.9 times. These results demonstrate the potential of GPR to measure the position and state of self-healing capsules, which are small-sized polymers, in real time using millimeter waves.

• Geomechanics and Engineering
• /
• v.30 no.6
• /
• pp.539-549
• /
• 2022

Accidental anchor drop can cause disturbances to seabed materials and pose significant threats to the safety and serviceability of submarine structures such as pipelines. In this study, a series of anchor drop tests was carried out to investigate the penetration mechanism of a Hall anchor in sand and clay. A special anchor drop apparatus was designed to model the inflight drop of a Hall anchor. Results indicate that Coriolis acceleration was the primary cause of large horizontal offsets in sand, and earth gravity had negligible impact on the lateral movement of dropped anchors. The indued final horizontal offset was shown to increase with the elevated drop height of an anchor, and the existence of water can slow down the landing velocity of an anchor. It is also observed that water conditions had a significant effect on the influence zone caused by anchors. The vertical influence depth was over 5 m, and the influence radius was more than 3 m if the anchor had a drop height of 25 m in dry sand. In comparison, the vertical influence depth and radius reduced to less than 3 m and 2 m, respectively, when the anchor was released from 10 m height and fell into the seabed with a water depth of 15 m. It is also found that the dynamically penetrating anchors could significantly influence the earth pressure in clay. There is a non-linear increase in the measured penetration depth with kinematic energy, and the resulted maximum earth pressure increased dramatically with an increase in kinematic energy. Results from centrifuge model tests in this study provide useful insights into the penetration mechanism of a dropped anchor, which provides valuable data for design and planning of future submarine structures.

• Journal of Trauma and Injury
• /
• v.36 no.4
• /
• pp.421-424
• /
• 2023

This case report presents the case of a 49-year-old man who presented to our level I trauma center after sustaining injuries in an altercation with local law enforcement in which he was shot with a less lethal bean bag and tased. In a primary survey, a penetrating left supraclavicular wound was noted in addition to a taser dart lodged in his flank. No other traumatic findings were noted in a secondary survey. Given hemodynamic stability, completion imaging was obtained, revealing a foreign body in the left lung, a left open clavicle fracture, a C5 tubercle fracture, a possible grade I left vertebral injury, and a left first rib fracture. Soft tissue gas was seen around the left subclavian and axillary arteries, although no definitive arterial injury was identified. The bean bag projectile was embedded in the parenchyma of the left lung on cross-sectional imaging. The patient underwent thoracotomy for removal of the projectile and hemostasis. A thoracotomy was chosen as the operative approach due to concerns about significant bleeding upon foreign body removal. A chest tube was placed and subsequently removed on postoperative day 5. The patient was discharged on postoperative day 7. At a 2-week outpatient follow-up visit, the patient was doing well. This case report is the first to describe this outcome for a drag-stabilized bean bag. Although law enforcement officers utilize bean bag projectiles as a "less lethal" means of crowd control and protection, these ballistics pose significant risk and can result in serious injury.

• International conference on construction engineering and project management
• /
• 2024.07a
• /
• pp.85-92
• /
• 2024

Reinforced concrete modular integrated construction (MiC) has been widely used in Hong Kong nowadays, but the solutions for temporary tying of the side walls during the construction of the composite wall have still shortcomings. Based on a MiC project in Hong Kong, this paper proposes a new inner tie system for composite wall. The system components are installed on the side walls of precast modules without penetrating through the side walls. After the loop is rotated to contact the hook, the tying effect can be generated when the concrete is poured on site between the middle gap of two modules. This system replaces tie bolts penetrating through precast side walls, so that the modules' interior fitting-out can be fully completed in factory and the on-site construction has no adverse effects on the internal decoration. This paper mainly describes the mechanism of the system, FEA simulation and optimization of the member size, as well as tensile and punching shear tests to verify the reliability, safety and to get more information about failure mode of the system. The system will be further examined by assembling 1:1 mockup modules, and finally applied to a real MiC project soon. The system can also act as permanent tie bars for the composite wall to reduce the total wall thickness, save the structural cost and increase the usable area. Compared with other existing tying methods in the industry, the system is easy to install, reliable to take loads, adaptable to large construction errors, and has the potential to be widely used in future practical projects.

• Development and Reproduction
• /
• v.14 no.4
• /
• pp.243-251
• /
• 2010

ESRRB (Estrogen related receptor $\beta$) is an orphan receptor, and have a role on maintaining the undifferentiated state and self-renewal of pluripotent stem cell as a transcription factor which regulates the expression of OCT4 and NANOG genes. Also, Feng et al. (2009) reported that Esrrb, Oct4 and Sox2 could induce pluripotent stem cell from somatic cells. The aim of the present study was to develop the direct delivery system of human ESRRB protein into human amniotic fluid-derived stem cells (AFSCs) and to analyze the effect of ESRRB on the regulation of pluripotency-related genes. Human ESRRB has three isoforms arisen by alternative splicing. We cloned short-form ESRRB and made a fusion protein of ESRRB and R7 for an efficient protein transfer to cell. R7 as cell-penetrating peptide(CPP) can help to transfer ESRRB into cells. R7-ESRRB-His6 protein was observed in the cytoplasm and nuclei within 5 hours after treatment. Also, we could observe R7-ESRRB-His6 protein only in the nuclei within 24 hours. Realtime PCR showed that ESRRB increased expression of OCT4 and NANOG as well as SOX2 gene. Therefore, we demonstrated that R7-ESRRB-His6 proteins were efficiently transferred into the nuclei of AFSCs and work well as a possible transcription factor.