• Journal of the Korean Wood Science and Technology
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• v.46 no.4
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• pp.355-361
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• 2018

In this study, the dimensional stability and mechanical properties of bamboo fiber-based composites (BFBCs) were studied at two pressing manufacturing processes, i.e., hot- and cold- pressing, and were compared with three density parameters (1.0, 1.1, and $1.2kg/m^3$). Width swelling ratio (WSR), thickness swelling ratio (TSR), and water absorption ratio (WAR) were calculated for water immersions of 4 and 28 h. WSR, TSR, and WAR for specimens immersed for 28 h were higher than those for 4 h treatment, which shows that the immersion time has a significant influence on the dimensional stabilities of BFBCs. Moreover, the positive linear relations between density and dimensional were observed at both the pressing ways, indicating that the WSR, TSR, and WAR decreased with an increase in the density of BFBCs. The compressive strength, shear strength, modulus of rupture (MOR), and modulus of elasticity (MOE) were determined. The compressive strength, MOR, and MOE of hot-pressed specimens were significantly higher than those for the cold-pressed specimens, which are also directly proportional to density. Moreover, the samples with the highest density of $1.2kg/m^3$ performed high values on mechanical properties in both the manufacturing methods.

• Journal of Chest Surgery
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• v.49 no.2
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• pp.73-79
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• 2016

Background: The aim of this study was to report our early experiences with the endovascular repair of ruptured descending thoracic aortic aneurysms (rDTAAs), which are a rare and life-threatening condition. Methods: Among 42 patients who underwent thoracic endovascular aortic repair (TEVAR) between October 2010 and September 2015, five patients (11.9%) suffered an rDTAA. Results: The mean age was $72.4{\pm}5.1years$, and all patients were male. Hemoptysis and hemothorax were present in three (60%) and two (40%) patients, respectively. Hypovolemic shock was noted in three patients who underwent emergency operations. A hybrid operation was performed in three patients. The mean operative time was $269.8{\pm}72.3minutes$. The mean total length of aortic coverage was $186.0{\pm}49.2mm$. No 30-day mortality occurred. Stroke, delirium, and atrial fibrillation were observed in one patient each. Paraplegia did not occur. Endoleak was found in two patients (40%), one of whom underwent an early and successful reintervention. During the mean follow-up period of $16.8{\pm}14.8months$, two patients died; one cause of death was a persistent type 1 endoleak and the other cause was unknown. Conclusion: TEVAR for rDTAA was associated with favorable early mortality and morbidity outcomes. However, early reintervention should be considered if persistent endoleak occurs.

• International Journal of High-Rise Buildings
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• v.9 no.3
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• pp.273-282
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• 2020

An innovative high-rise timber-concrete hybrid structure was proposed in previous research, which is composed of the concrete frame-tube structure and the prefabricated timber modules as main structure and substructures, respectively. Considering that the timber substructures are built on the concrete floors at a different height, the floor response spectrum is more effective in estimating the seismic response of substructures. In this paper, the floor response spectra of the hybrid structure with different structural parameters were calculated using dynamic time-history analysis. Firstly, one simplified model that can well predict the seismic response of the hybrid structure was proposed and validated. Then the construction site, the mass ratio and the frequency ratio of the main-sub structure, and the damping ratio of the substructures were discussed. The results demonstrate that the peaks of the floor response spectra usually occur near the vibration periods of the whole structure, among which the first two peaks stand out; In most cases, the acceleration amplification effect on substructures tends to be more evident when the construction site is farther from the fault rupture; On the other hand, the acceleration response of substructures can be effectively reduced with an appropriate increase in the mass ratio of the main-sub structure and the damping ratio of the substructures; However, the frequency ratio of the main-sub structure has no discernible effect on the floor response spectra. This study investigates the characteristics of the floor response spectrum of the novel timber-concrete structure, which supports the future applications of such hybrid structure in high-rise buildings.

• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.80-88
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• 2016

A fire station and scuba have operated filling facilities for respiratory high-pressure cylinder without getting authority or reporting according to High-Pressure Gas Safety Control Act. They need facility improvement and special management to make provision for the time of accident during filling process. The Government have strived to correct illegal operations and suggested an alternative, establishing and operating the safety cabinet. It insures a safety being distance from danger caused by overpressure and a safety provoked by the protective wall equals or superiors. The safety cabinet is required to have an internal structure that smoothly distribute overpressure at the time of rupture. Plus, it needs to minimize fragments. It is also equipped with the performance of protective wall that makes overpressure to outside vent on the place where there is no person (top or bottom). This study calculated the consequence of physical explosion damage and built a prototype of safety cabinet. In addition, through the gas burst test, it derives for the ways to mitigate the physical explosion damage.

• Explosives and Blasting
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• v.39 no.4
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• pp.22-33
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• 2021

Recently, the frequent occurrence of ground subsidence in urban areas has caused increasing anxiety in residents and incurred significant social costs. Among the causes of ground subsidence, the rupture of old water and sewer pipes not only halts the operation of the buried pipes, but also leads to ground and water pollution problems. However, because most pipes are buried after construction and cannot be seen with the naked eye, the importance of maintenance has underestimated compared to other structures. In recent years, integrated physical exploration has been applied to the maintenance of underground pipes and structures. Currently, to investigate the internal conditions and vulnerable portions of the ground, consolidated physical surveys are executed. Consolidated physical surveys are analysis techniques that obtain various material data and add existing data using multiple physical surveys. Generally, in geotechnical engineering, consolidated physical surveys including electrical and surface wave surveys are adopted. However, it is difficult to investigate time-based changes in under ground using these surveys. In contrast, surveys using cosmic-ray muons have been used to scan the inner parts of nuclear reactors with penetration technology. Surveys using muons enable real-time observation without the influence of vibration or electricity. Such surveys have great potential for available technology because of their ability to investigate density distributions without requiring as much labor. In this paper, survey technologies using cosmic ray muons are introduced, and the possibilities of applying such technologies as new physical survey technologies for underground structures are suggested.

• Cross-Cultural Studies
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• v.34
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• pp.93-114
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• 2014

Gaston Bachelard had a revolutionary progress in the field of human understanding by proposing his theory of image and imagination. His theory of the new image was so powerful, almost all areas of human science, particularly that of literary criticism, were strongly influenced and this influence continues until today. Today almost everyone accepts his theory of the image without much objection, but not rarely asked where began his transfer from the philosophy of science to the images. We propose a hypothesis that the beginning of the new concept of Bachelard's image was inspired by studies of contemporary science, especially quantum mechanics. The Heisenberg's uncertainty principle was the core of quantum mechanics, and opens new perspectives on the material world. We could summarize the message of the uncertainty principle : the material world is made up of various layers, and the material can not be measured by the location and movement at the same time. So we must have a new point of view of another dimension to know this material world. Bachelard had accepted this view of Heisenberg and developed his own theory of epistemological rupture. What is revolutionary in the theory of Bachelard's image is the fact that he looked at the images with the new perspective. The human psyche is another world compared to the rational world that dominates our daily lives. Bachelard insists that the image can not be explained by the concept. The fantasy world is a totally different world to that of rationality. That is why it can not be explained by the language of rationality as the concept. The imaginary world exists independently of the real world, but it is superimposed on the real world. These two worlds are influencing each other, and it is between these two world where our daily lives continues. The declaration of Bachelard 'image is a specific reality' is never a metaphor or rhetorical expression. This is an ontological expression that must truthfully. The imaginary world is a world built on the image and it works according to its own law. It is not a representation or copy of the real world. But the world of imagination are not alone. It exists in the same time and space with the world of science. It is superimposed with the world of science. Both two world influence each other. Bachelard has made a revolutionary change by studying the images. He gave them their own place. It has changed the views on the images that were treated as mere representations of reality. Thanks to him, the image can have its own value, that of a factor that creates reality. Bachelard shows how we can go deep into the source of being and the universe if we look at the pictures with the eyes of other dimensions.

• Journal of Korean Neurosurgical Society
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• v.62 no.5
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• pp.536-544
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• 2019

Objective : The objective of this study was to evaluatelong-term radiologic prognosis and characteristics of in-stent stenosis (ISS) after stent assisted coiling (SAC) for cerebral aneurysm and analyze its risk factors. Methods : Radiological records of 362 cases of SAC during 10 years were retrospectively reviewed. Patients were included in this study if they had follow-up angiogram using catheter selected angiography at least twice. All subjected were followed up from 12 months to over 30 months. Of 120 patients, 123 aneurysms were enrolled. Patient data including age, sex, aneurysm size, neck size, procedural complication, kinds of stent, ISS associated symptom, ruptured state, location of ISS, degree of ISS, radiologic prognosis of ISS, follow-up period of time, and medical comorbidities such as hypertension, diabetes mellitus (DM), dyslipidemia, and smoking were collected.Statistical comparisons of group clinical characteristics were conducted for the total population. Results : Among 123 casesof aneurysm, 22 cases (17.9%) of ISS were revealed on follow-up angiography. Multiple stenting was performed in three cases and intra-procedural rupture occurred in two cases. Most cases were asymptomatic and symptomatic stenosis was identified in only one case. Sixteen cases were ruptured aneurysm. Mild stenosis was observed in 11 cases. Moderate stenosis was found in eight cases and severe stenosis was identified in three cases. Mean timing of identification of ISS was 8.90 months. The most common type was proximal type. Most cases were improved or not changed on follow-up angiography. Only one case was aggravated from mild stenosis to occlusion of parent artery. Mean follow-up period was 44.3 months. We compared risk factors and characteristic between ISS group and non-ISS group using univariate analysis. Multiple stenting was performed for three cases (13.6%) of the ISS group and four cases (4.0%) of the non-ISS group, showing no statistical difference between the two groups (p=0.108). Additionally, the proportion of patients who had more than two risk factors among four medical risk factors (hypertension, DM, dyslipidemia, and smoking) was higher in the ISS group than that in the non-ISS group, the difference between the two was not statistically significant either (31.8% vs. 12.9%, p=0.05). Conclusion : Clinical course and long-term prognosis of ISS might be benign. Most cases of ISS could be improved or not aggravated. Control of medical co-morbidity might be important. To the best of our knowledge, our study had more cases with longer follow-up period of time than other reports.

• Journal of Chest Surgery
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• v.32 no.6
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• pp.532-535
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• 1999

Background: The purpose of this study was to evaluate and analyze the surgical techniques and postoperative complications in patients undergoing operations for descending thoracic aortic aneurysms. Material and Method: The data of 22 major operations between March 1987 and August 1997 were retrospectively reviewed. Result: There were 18 men and 4 women with a mean age of 49 years (range 33 years to 82 years). The cause of the aneurysm was aortic dissection in 13 patients, atherosclerosis in 3, mycotic in 3, trauma in 2 and uncertain in 1. The operative techniques were resection and graft replacement in 16, axillofemoral bypass graft in 2, femorofemoral bypass graft in 2, exclusion, aneurysmorrhaphy in 1 and transfemoral stent insertion in 1. During the operation, 16 cases were performed under total aortic clamp. Among the 16 patients, femorofemoral bypass was used in 14 cases and previously made shunt in 2 cases. The mean total aortic clamp time was 91 minutes and the mean extracorporeal circulation time was 116 minutes. One death occurred in an excluded patient on the 52 postoperative day due to a rupture of the aneurysm. Postoperative complications were paraplegia in 1 case, acute renal failure in 1 case and acute respiratory failure in 1 case. Conclusion: Although surgical treatment of the descending thoracic aneurysm has many postoperative complications, good surgical results can be achieved with a proper patient selection and fine surgical techniques.

• Journal of Chest Surgery
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• v.35 no.4
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• pp.267-273
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• 2002

Background: We performed a phase IV clinical trial to examine the usefulness of a continuous infusion of nicardipine hydrochloride to control hypertension in patients with acute aortic dissection. material and Method: Systolic/diastolic blood pressure, and heart rate were monitored before and after the intravenous administration of nicardipine in 31 patients with aortic diseases. The period of nicardipine administration in each patient was from 3 to 14 days. Efficacy was evaluated by determining the average amount of blood pressure reduction on the 3rd day of drug administration. The dosage of another antihypertensive agent was slowly tapered down, and ultimately replaced by the test drug. Result: 28 patients were diagnosed as acute aortic dissection, 2 patients as rupture of the aortic arch aneurysm, and 1 patient as traumatic aortic rupture. Mean age was 53.9 $\pm$ 14.9(29~89) years, and 21 patients(67.7%) were male. 14 patients(32.3%) had complications associated with underlying aortic disease: aortic insufficiency in 7, hemopericardium in 6, acute renal failure in 1, paraplegia in 1, lower extremity ischemia in 1, and hemothorax in 1. The time needed to reach the target blood pressure was within 15 minutes in 16, from 15 to 30 minutes in 10, from 30 to 45 minutes in 3 and from 45 to 60 minutes in 2, and their baseline average systolic, diastolic, and mean arterial blood pressures(mmHg) were 147$\pm$23, 82.3$\pm$ 18.6, and 104 $\pm$ 18, respectively. Average systolic, diastolic, and mean arterial blood pressures(mmHg) on the third day of nicardipine infusion were 119$\pm$ 12, 69$\pm$9, and 86$\pm$8, and they all showed statistically significant decrease(p<0.05). The average systolic, diastolic, and mean arterial blood pressure(mmHg) after the discontinuation of the nicardipine infusion were 119 $\pm$ 15, 71 $\pm$ 14, and 86$\pm$ 13, respectively. No significant difference was observed between the average pressures measured on the third day and those measured after the discontinuation of the nicardipine infusion, and no definite side effects were observed during the study period. Conclusion: Nicardipine hydrochloride was both effective and safe at controlling blood pressure in patients with acute aortic dissection.

• Journal of Chest Surgery
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• v.42 no.3
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• pp.331-336
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• 2009

Background: Open surgical repair of abdominal aortic aneurysms was initiated by Dubost in 1952. Despite the rapid expansion of percutaneous endovascular repair, open surgical repair is still recognized for curative intent. We retrospectively analyzed surgical outcome, complications, and mortality-related factors for patients with abdominal aortic aneurysms over a 6 year period. Material and Method: We analyzed 18 patients who underwent surgery for abdominal aortic aneurysms between March 2002 and March 2008. The indications for surgery were rupture, a maximal aortic diameter >60 mm, medically intractable hypertension, or pain. Result: The mean age was $66.6{\pm}9.3$ years (range, $49\sim81$ years). Twelve patients (66.7%) were males a 6 patients were females. Extension of the aneurysm superior to the renal artery existed in 6 patients (33.3%), and extension to the iliac artery existed in 13 patients (72.2%). Five patients (27.8%) had ruptured aortic aneurysms. The mean maximal diameter of the aorta was $72.2{\pm}12.9$ mm (range, $58\sim109$ mm). Surgery was performed by a midline laparotomy, and 6 patients underwent emergency surgery. The mean total ischemic time from aorta clamping to revascularization was $82{\pm}42$ minutes (range, $35\sim180$ minutes). The mortality rate was 16.7%; the mortality rate for patients with ruptured aneurysms was 60%, and the mortality rate for patients with unruptured aneurysms was 0%. The postoperative complications included one each of renal failure, femoral artery and vein occlusion, and wound infection. The patients who were discharged had a long-term survival of $34{\pm}26$ months (range, $4\sim90$ months). Rupture and emergency surgery had a statistically significant mortality-related factor (p < 0.05). Conclusion: Emergency surgery for ruptured aortic aneurysms continues to have a high mortality, but unruptured cases are repaired with relative safety. Successfully operated patients had long-term survival. Even though endovascular aortic repair is the trend for abdominal aortic aneurysms, aggressive application should be determined with care. Experience and systemic support of each center is important in the treatment plan.