• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.2
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• pp.161-173
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• 2013

When the ground is excavated near the pre-existing structures due to the region restricted condition such as urban area, the ground will be released by the excavation and the temporary wall will be deformed depending on the earth pressure. In this case, issues can be created in terms of stability of pre-existing structures. Firstly, the laboratory model tests were carried out to investigate the ground surface settlement due to the ground excavation according to the excavation methods in this study. Using the ground surface settlement results from model tests, numerical analyses were carried out to study the structure deformation due to the ground excavation according to the excavation methods. Finally, using the structure deformation results from numerical analysis, the damage assessment of structures was carried out by using the strain damage estimation criterion.

• Geomechanics and Engineering
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• v.36 no.3
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• pp.231-245
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• 2024

In recent decades, the protection and vulnerability of civil structures under explosion loads became a critical issue in terms of security, which may cause loss of lives and structural damage. Concrete retaining walls also restrict soils and slopes from displacements; meanwhile, intensive temporary loading may cause massive damage. In the current study, the modified Johnson-Holmquist (also known as J-H2) material model is implemented for concrete materials to model damages into the ABAQUS through user-subroutines to predict the blasting-induced concrete damages and volume strains. For this purpose, a 3D finite-element model of the concrete retaining wall was conducted in coupled Eulerian-Lagrangian simulation. Subsequently, a blast load equal to 500 kg of TNT was considered in three different positions due to UFC 3-340-02. Influences of the critical parameters in smooth blastings, such as distance from a free face, position, and effective blasting time, on concrete damage rate and destroy patterns, are explored. According to the simulation results, the concrete penetration pattern at the same distance is significantly influenced by the density of the progress environment. The result reveals that the progress of waves and the intensity of damages in free-air blasting is entirely different from those that progress in a dense surrounding atmosphere such as soil. Half-damaged elements in air blasts are more than those of embedded explosions, but dense environments such as soil impose much more pressure in a limited zone and cause more destruction in retaining walls.

• Journal of Trauma and Injury
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• v.23 no.2
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• pp.63-67
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• 2010

Purpose: A tension pneumothorax is a fatal condition that requires immediate intervention. Although a definitive treatment for a tension pneumothorax is a tube thoracostomy, needle decompression can provide temporary relief, that is lifesaving. The traditional procedure for needle decompression involves inserting a needle or catheter at the second intercostal space, the midclavicular line. Recent evidence suggests that the commonly used catheters do not have sufficiently penetrate the chest wall. There are also claims that a lateral approach to needle decompression is easier and safer than the traditional anterior approach. The purpose of this study is to evaluate the optimal approach for needle decompression for the Korean population by measuring chest wall thicknesses at the points used for both the anterior and the lateral approaches. Methods: The chest wall thickness (CWT) of trauma victims who visited the Emergency Center of Pusan National University Hospital was measured by computed tomography (CT) images. The CWT was measured at the points used for the anterior and the lateral methods and was compared with the length of commonly used catheters, which is 45 mm. Results: The mean CWT at the second intercostal space, the midclavicular line, was shorter than the CWT at the 5th intercostal space, the anterior axillary line. However, the percentage of patients whose CWT was greater than 45 mm was larger when measured anteriorly (8.2%) that when measure laterally (5.7%). Female patients and those older than 60 were more likely to have an anterior CWT greater than 45 mm (28.2% for females and 15.5% for those older than 60). Conclusion: The percentage of trauma victims in Korea whose CWT is greater than 45 mm is lower than the values previously reported by other countries. However, females and older patients tend to have thicker chest walls, so the lateral approach would be suggested when performing needle decompression for such patients with suspected tension pneumothoraces.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1046-1050
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• 2010

During construction of a sea-crossing bridge grouting was used to fill densely the space between the bottom of caisson and the ground. This grout mixture was mixed with an anti-washout admixture after locating accurately the pre-cast caisson on three concrete landing pads. This method differs significantly from the costly conventional method, for bridge foundations offshore, where concrete is placed in situ after excavating inside of a temporary concrete coffering wall. To verify the grouting method in advance, the full-scale field tests were performed twice on land. After identifying the fluidity of the grout material to be filled, finding some possible problems with the main construction and revising the original design, the main construction has been continuing successfully with 20 caissons completed to date. The purpose of this paper is to introduce for the first time in Korea the grouting method including the automatic and the manual monitoring system based on the main construction of the caisson foundation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.109-110
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• 2018

Preloading Strut applied during installation of the wall jack, but additionally serves to minimize the displacement of soil pressure acting upon dissolution due to the difficulty. In this study, we developed an index of support for the release of stress to facilitate the dismantling of the strut uninstall. The refractive support the axial force acting on the strut are supportable, is refracted at minimum load, disassembly should be easy. In order to find the optimal shape and structural stability of the refractive support We have performed the numerical analysis and performance test to determine the final model. We carried out model tests and UTM test in order to understand the refractive performance and durability of the refractive support for optimal model. Results of the test UTM is refracted all shot 5 times within a target hit number, it was found that there is no problem of the refractive performance. Further, the results of model experiments, it was found that to ensure sufficient durability more than the performance target value of the pin joint support structure.

• 기술발표회
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• s.2006
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• pp.135-145
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• 2006

Soil nailing systems are generally many used in underground excavations and reinforcements of slopes since the first construction as a temporary retaining wall in 1993, Korea. In recently, they are many attempts to expand the permanent reinforcements of slopes However, experimental studies related to soil nailing systems are insufficient Specially, there are no researches related in the large scaled load tests of soil nailed walls in Korea In this study, a case study on the large scaled load tests of soil nailed walls is introduced and the behavior characteristic of them is investigated Also, they are proposed allowable deformation corresponding to the serviceability limit of soil nail walls and ultimate deformation corresponding to the collapse state of the walls. These results can be applied to the maintenance management of soil nailed walls And analysis on the required minimum factor of safety of soil nailed walls using the relation curve of load ratio and deformation ratio are carried out

• Korean Journal of Bronchoesophagology
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• v.18 no.2
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• pp.56-59
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• 2012

Tracheo-innominate artery fistula (TIF) is a rare but catastrophic and almost always fatal complication of tracheostomy. TIF can occur anytime but is commonly present 3 to 24 days after tracheostomy. It can first manifest as massive bleeding around and through the tracheostomy tube, but it can also manifest as a small amount of blood with temporary spontaneous resolution. If TIF is suspicious, airway management and prompt surgical intervention are needed. In an 83-year-old man with CVA history 20 years earlier and who had recurrent aspiration pneumonia, tracheostomy was performed for respiratory management and ventilator support. On day 7 post-tracheostomy, the patient had bleeding from the tracheostoma. Immediate surgical exploration was performed to control the bleeding. A defect was seen at the post wall of the innominate artery. The erosive portion of the artery was sutured, but the patient died three weeks after the surgery due to rebleeding and respiratory failure. We present a patient who developed TIF after tracheostomy, with literature review.

• Journal of the Korean Geosynthetics Society
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• v.3 no.1
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• pp.37-42
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• 2004

In the reinforced retaining wall system, non-woven geotextiles are placed at the face of reinforced earth until the facing blocks are built up. And when this system is used as temporary structure, geotextiles facings are exposed to sunlight during service lifetime. During these periods, degradation of nonwoven geotextiles are occurred by UV light. So the UV-resistance of nonwoven geotextiles must be assessed correctly, in considering of the site conditions. In this study, laboratory test and the field test have been performed to evaluate the UV resistance of non-woven geotextiles used in KOESWall system and the results are expressed in terms of tensile characteristics & SEM photographs.

• Journal of the Korean Geotechnical Society
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• v.38 no.1
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• pp.35-45
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• 2022

When constructing a cylindrical vertical shaft through the open-cut method, the walls are generally designed to be temporary flexible walls that allow a certain level of displacement. The earth pressure applied to the flexible walls acts as an external force and its accurate estimation is essential for reasonable and economical structure design. The earth pressure applied to the flexible wall is closely interrelated to the plastic deformation of the surrounding ground. This study simulated a stepwise excavation for constructing a cylindrical vertical shaft through a centrifugal model test and evaluated the continuous deformation behaviors of the surrounding ground through digital image analysis.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.34 no.1
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• pp.1-17
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• 2016

The purpose of this paper is to understand the value of Dongji(東池), Seoji(西池) and Namji(南池), the lotus ponds of Fortress Wall of Seoul as part of the cultural landscape of the period through a consideration of personal behavior and impressive landscape characteristics via various old writings on each pond. The objects of this study include poems, diaries, travelogues and essays describing these ponds. The results are as follows. First, the preferred landscape elements of these three ponds were lotuses, willows and water itself. Second, while Dongji was recognized as a natural landscape, the composition of Seoji was a mixture of with natural and urban landscapes, and Namji was more urban altogether. Third, in aspects of personal behavior, while Dongji was a place where people broke their journeys to gaze at the scenery or looked down distantly, in Seoji, people stayed for a long time in a pavilion called Cheonyeon-jeong(天然亭) and engaged in various leisure activities, and in Namji, there were many gatherings under a temporary shelter or at a friend's house near the pond. Night was the best time to enjoy Namji because during the day, the area was crowded with people, horses, carts and so on. Fourth, the landscapes of fortress walls were impressively described often. Fifth, because these ponds were integrated into the surrounding area, they were like public openspaces mixed with water spaces, natural environment and adjacent facilities. The lotus ponds of the Fortress Wall of Seoul were located in a place connecting inside and outside of fortress, supplemented the cultural features in city, were valued as public openspace, and made it possible to experience the unique landscape of Hanyang. Although these ponds were buried and have now disappeared, they still hold great cultural meaning and potential value as water landscapes of the old city.