• Journal of the Korean Society of Safety
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• v.9 no.1
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• pp.110-120
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• 1994

The Quantitative analysis for collapsion probability of each construcion work has not been developed, despite of that the one for safety management itself has been reported, up to now. It is concluded that showing critical check points against structure collapsion due to each work at construction site, and Quantifying those could be useful Quality-assuring tool, not to prevent Quality failure. Risk classes of each work at construction site, classified by German Builders Mutual-Aid Association (GEBMAS), and by special instruction rates of Korea Insurance Development Institute, are introduced to compare with the results of this study. As of a study method, total 2,002 sheets of questionwares are distributed directly to new city development areas, which are called, Ilsan 110 points : Pundang 79points and Chungdong 38points, including additional Changwon 125sheets and pusan 60sheets, by four(4) people, for contact with actual site engineers. Total responses of 1,056 sheets, are collected. Interrelationship diagram between experience years of Engrs., and risk rate of responses are also classified, with the criteria of four(4) years. Domestic journals with relation to construction have reported that main building Structure collapsions are mainly shown on apartment buildings and office ones. These two(2) building structures are again classified as five(5) kinds of works. This study takes use of an approach on haying the risk rates for each construction work on the above individual construction work. Additionally, site investigations have been performed to find out any possible unreasonable check items, due to construction method ; Reinforced Concret structure, Pre cast Concrete structure, and Steel structure building. Developed Quality Assurance Analysis Form with the Quantitative danger class, resulted from this study, are verified as it is able to be a good efficiency tool against collapsion of building structures.

• Geomechanics and Engineering
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• v.15 no.2
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• pp.721-728
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• 2018

The surrounding rock mass contains cracks and joints which are distributed randomly around tunnels, and in the process of tunnel blasting excavation, radial cracks could also be induced in the surrounding rock mass. In order to clearly understand the impact of radial cracks on tunnel stability, tunnel model tests and finite element numerical analysis were implemented in this paper. Two kinds of materials: cement mortar and sandstone, were used to make tunnel models, which were loaded vertically and confined horizontally. The tunnel failure pattern was simulated by using RFPA2D code, and the Tresca stresses and the stress intensity factors were calculated by using ABAQUS code, which were applied to the analysis of tunnel model test results. The numerical results generally agree with the model test results, and the mode II stress intensity factors calculated by ABAQUS code can well explain the model test results. It can be seen that for tunnels with a radial crack emanating from three points on tunnel edge, i.e., the middle point between tunnel spandrel and its top with a dip angle $45^{\circ}$, the tunnel foot with a dip angle $127^{\circ}$, and the tunnel spandrel with $135^{\circ}$ with tunnel wall, the tunnel model strength is about a half of the regular tunnel model strength, and the corresponding tunnel stability decreases largely.

• Journal of Navigation and Port Research
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• v.34 no.6
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• pp.405-415
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• 2010

To assess the possible collision risk between Mokpo Harbour Bridge, which is under construction, and passing vessels, we proposed Real-Time Bridge-Vessel Collision Model (RT-BVCM) in this paper. The mathematical model of RT-BVCM consists of the causation probability by the vessel aberrancy due to navigation environments, the geometric probability by the structural feature of a bridge relative to a ship size and, the failure probability by the ship collision track and the stopping distance which is not to come to a stop before hitting the obstacles. Then, the probabilistic mathematical model represented as risk index with the risk level from 1 to 5. The merit of the proposed model to the collision model proposed by AASHTO (American Association of State Highway and Transportation Officials) is that it can provide enough time to take adequate collision avoiding action. Through the simulation tests to the two kinds of test ships, 3,000 GT and 10,000 GT, it is cleary found that the proposed model can be used as a collision evaluation model to the passing vessel and Mokpo Harbour Bridge.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.3
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• pp.199-212
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• 2007

If a type IP-2 transport package were to be subjected to a free drop test and a penetration test under the normal conditions of transport, it should prevent a loss or dispersal of the radioactive contents and a more than 20% increase in the maximum radiation level at any external surface of the package. In this paper, we suggested the analytic method to evaluate the structural safety of a type IP-2 transport package using a thick steel plate for a structure part and a bolt for tying a bolt. Using an analysis a loss or dispersal of the radioactive contents and a loss of shielding integrity were confirmed for two kinds of type IP-2 transport packages to transport radioactive waste drums from a waste facility to a temporary storage site in a nuclear power plant. Under the free drop condition the maximum average stress at the bolts and the maximum opening displacement of a lid were compared with the tensile stress of a bolt and the steps in a lid, which were made to avoid a streaming radiation in the shielding path, to evaluate a loss or dispersal of radioactive waste contents. Also a loss of shielding integrity was evaluated using the maximum decrease in a shielding thickness. To verify the impact dynamic analysis for free drop test condition and evaluate experimentally the safety of two kinds of type IP-2 transport packages, free drop tests were conducted with various drop directions. For the tests we examined the failure of bolts and the deformation of flange to evaluate a loss or dispersal of radioactive material and measured the shielding thickness using a ultrasonic thickness gauge to assess a loss of shielding integrity. The strains and accelerations acquired from tests were compared with those by analyses to verify the impact dynamic analysis. The analytic results were larger than the those of test so that the analysis showed the conservative results. Finally, we evaluated the safety of the type IP-2 transport package under the stacking test condition using a finite element analysis. Under the stacking test condition, the maximum Tresca stress of the shielding material was 1/3 of the yielding stress. Two kinds of a type IP-2 transport package were safe for the free drop test condition and the stacking test condition.

• Geomechanics and Engineering
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• v.9 no.5
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• pp.619-629
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• 2015

Influenced by various mining activities, fractures in rock masses have different densities, set numbers and lengths, which induce different mechanical properties and failure modes of rock masses. Therefore, precisely expressing the failure criterion of the fractured rock influenced by coal mining is significant for the support design, safety assessment and disaster prevention of underground mining engineering subjected to multiple mining activities. By adopting PFC2D particle flow simulation software, this study investigated the propagation and fractal evolution laws of the micro cracks occurring in two typical kinds of rocks under uniaxial compressive condition. Furthermore, it calculated compressive strengths of the rocks with different confining pressures and box-counting dimensions. Moreover, the quantitative relation between the box-counting dimension of the rocks and the empirical parameters m and s in Hoek-Brown strength criterion was established. Results showed that with the increase of the strain, the box-counting dimension of the rocks first increased slowly at the beginning and then exhibited an exponential increase approximately. In the case of small strains of same value, the box-counting dimensions of hard rocks were smaller than those of weak rocks, while the former increased rapidly and were larger than the latter under large strain. The results also presented that there was a negative correlation between the parameters m and s in Hoek-Brown strength criterion and the box-counting dimension of the rocks suffering from variable mining activities. In other words, as the box-counting dimensions increased, the parameters m and s decreased linearly, and their relationship could be described using first order polynomial function.

• Archives of Reconstructive Microsurgery
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• v.5 no.1
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• pp.24-34
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• 1996

There are many kinds of free flaps for management of extensive soft tissue defect of extremities in orthopaedic field. Free vascularized scapular flap is one of the most useful and relatively easy to application. This flap has been utilize clinically from early eighties by many microsurgical pioneers. Authors performed 102 cases of this flap from 1984 to 1995. We have to consider about the surgical anatomy of the flap, technique of the donor harvesting procedures, vascular varieties and anatomical abnormalities and success rate and the weak points of the procedure. This flap nourished by cutaneous branches from circumflex scapular vessels emerges from the lateral aspect of the subscapular artery 2.5-5cm from its lateral origin passing through the triangular space(bounded by subscapularis, teres minor, teres major, long head of triceps). The terminal cutaneous branch runs posteriorly around the lateral border of the scapular and divided into two major branches, those transeverse horizontally and obliquely to the fascial plane of overlying skin of the scapular body. We can utilize these arteries for scapular and parascapular flap. The vascular pedicle ranged from 5 to 10 cm long depends on the dissection, usually two venae comitantes accompanied circumflex scapular artery and its major branches. The diameter of the circumflex scapular artery is more than 1mm in adult, rare vascular variation. Surgical techniques : The scapular flap can be dissected conveniently with prone or lateral decubitus position, prone position is more easier in my experience. There are two kinds of surgical approaches, most of the surgeon prefer elevation of the flap from its outer border towards its base which known easier and quicker, but I prefer elevation of the flap from its outer border because of the lowering the possibilities of damage to vasculature in the flap itself which runs just underneath the subcutaneous tissue of the flap and provide more quicker elevation of the flap with blunt finger dissection after secure pedicle dissection and confirmed the course from the base of the pedicle. There are minimal donor site morbidity with direct skin closure if the flap size is not so larger than 10cm width. This flap has versatility in the design of the flap shape and size, if we need more longer and larger one, we can use parascapular flap or both. Even more, the flap can be used with latissimus dorsi musculocutaneous flap and serratus anterior flap which have common vascular pedicle from subscapular artery, some instance can combined with osteocutaneous flap if we include the lateral border of the scapular bone or parts of the ribs with serratus anterior. The most important shortcoming of the scapular free flap is non sensating, there are no reasonable sensory nerves to the flap to anastomose with recipient site nerve. Results : Among our 102 cases, overall success rate was 89%, most of the causes of the failure was recipient site vascular problems such as damaged recipient arterial conditions, and there were two cases of vascular anomalies in our series. Patients ages from 3 years old to 62 years old. Six cases of combined flap with latissimus dorsi, 4 cases of osteocutaneous flap for bone reconstruction, 62 parascapular flap was performed - we prefer parascapular flap to scapular. Statistical analysis of the size of the flap has less meaningful because of the flap has great versatility in size. In the length of the pedicle depends on the recipient site condition, we can adjust the pedicle length. The longest vascular pedicle was 14 cm in length from the axillary artery to the enter point cutaneous tissue. In conclusion, scapular free flap is one of the most useful modalities to manage the large intractable soft tissue defect. It has almost constant vascular pedicle with rare anatomical variation, easy to dissect great versatility in size and shape, low donor morbidity, thin and hairless skin.

• Journal of Korean Neurosurgical Society
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• v.29 no.5
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• pp.664-667
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• 2000

Objective : Excessive bleeding from the exposed cancellous bone surface may cause serious problem such as hematoma formation, infection, transfusion reaction during operation and postoperative period. There are several kinds of bleeding control agent on the cancellous bone surface including bone wax, gelatin sponge ($Gelfoam^{(R)}$), oxidized cellulose($Oxycel^{(R)}$, $Surgicel^{(R)}$), thrombin, microfibrillar collagen($Avitene^{(R)}$) etc. In the past, bone wax was used to control bone bleeding but it is associated with increased infection rate and fusion failure. Recently, gelfoam paste has been used to control cancellous bone bleeding. We controlled the cancellous bone bleeding with the mixture of gelfoam powder and thrombin powder. Material and Methods : Seventeen patients of posterior fusion on the 4 motion segments of thoracolumbar spine were selected to compare the result of bone bleeding control. In the test group of 9 patients, the cancellous bone bleeding was controlled with the mixture of Gelfoam and thrombin powder during operation. In the control group of 8 cases, no chemical hemostatic agent was used to manage the bone bleeding during operation. We calculated the total amount of bleeding from cancellous bone surface during and after operation in the two groups and compared their statistic significance of the result which was judged by student t-test. Results : The average amount of intraoperative bleeding was 1825ml in control group, 811ml in test group(p<0.01). The amount of postoperative bleeding was 943ml in control group and 812ml in test group, there were no significant difference in the amount of bleeding during postoperative period between two groups(p>0.5). Total amount of blood was decreased in as much as 1150ml in test group(p<0.01). Conclusion : We concluded that the application of the mixture of thrombin and gelfoam powder on the cancellous bone surface is the effective control method of cancellous bone bleeding for multilevel posterior spinal fusion.

• Childhood Kidney Diseases
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• v.13 no.2
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• pp.130-137
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• 2009

Purpose : Stem cell transplantation (SCT) has gained worldwide acceptance as a treatment for hematologic disorders. This study was performed to evaluate the clinical characteristics and outcomes of the acute kidney injury after SCT in children. Methods : The records of 53 patients who were treated with SCT at the pediatric department of Yeungnam University Hospital between January, 1996 and April, 2009 were used as subjects. Their were divided into two groups ; 'Early renal insufficiency' (ERI, n=18) and 'Non-early renal insufficiency' (NERI, n=35). ERI had greater than 25% of drop in GFR after SCT. Results: Total 53 patients were analyzed. In cord blood SCT (n=11), ERI was 4 (36.4%) and NERI was 7 (63.6%). In bone marrow SCT (n=16), ERI was 8 (50.0%) and NERI was 8 (50.5%). In autologous peripheral blood SCT (n=26), ERI was 6 (23.1%) and NERI was 20 (76.9%). There is no difference in both groups according to kinds of SCT. GVHD was developed in 22 patients, and there is no difference in each group. Twenty two of 53 patients died. ERI was 12 (66.7%) and NERI was 10 (28.6%). Acute renal failure is most important cause of the deaths. Conclusion : Out of 53 pediatric patients who were treated with SCT, 18 patients had greater than 25% of drop in GFR. There is no difference in both groups according to kinds of SCT. GVHD was found in 22 patients and there is no relation between GVHD development and acute kideney injury.

• Journal of Chest Surgery
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• v.37 no.1
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• pp.27-34
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• 2004

Background: Infective endocarditis shows higher operative morbidity and mortality rates than other cardiac diseases. The vast majority of studies on infective endocarditis have been made on aortic endocarditis, with little attention having been paid to infective endocarditis on the mitral valve. This study attempts to investigate the clinical aspects and operative results of infective endocarditis on the mitral valve. Meterial and Method: The subjects of this study consist of 23 patients who underwent operations for infective endocariditis on the mitral valve from June 1995 to May 2003. Among them, 2 patients suffered from prosthetic valvular endocarditis and the other 21 from native valvular endocarditis. The subjects were evenly distributed age-wise with an average age of 44.8$\pm$15.7 (11∼66) years. Emergency operations were performed on seventeen patients (73.9%) due to large vegetation or instable hemodynamic status. In preoperative examinations, twelve patients exhibited congestive heart failure, four patients renal failure, two patients spleen and renal infarction, and two patients temporary neurological defects, while one patient had a brain abscess. Based on the NYHA functional classification, seven patients were determined to be at Grade II, 9 patients at Grade III, and 6 patients at Grade IV. Vegetations were detected in 20 patients while mitral regurgitation was dominant in 19 patients with 4 patients showing up as mitral stenosis dominant on the preoperative echocardiogram. Blood cultures for causative organisms were performed on all patients, and positive results were obtained from ten patients, with five cases of Streptococcus viridance, two cases of methicillin-sensitive Staphylococcus aureus, and one case each of Corynebacteriurn, Haemophillis, and Gernella. Operations were decided according to the AA/AHA guidelines (1988). The mean follow-up period was 27.6 $\pm$23.3 (1 ∼ 97) months. Result: Mitral valve replacements were performed on 43 patients, with mechanical valves being used on 9 patients and tissue valves on the other 4. Several kinds of mitral valve repair or mitral valvuloplasty were carried out on the remaining 10 patients. Associated procedures included six aortic valve replacements, two tricuspid annuloplasty, one modified Maze operation, and one direct closure of a ventricular septal defect. Postoperative complications included two cases of bleeding and one case each of mediastinitis, low cardiac output syndrome, and pneumonia. There were no cases of early deaths, or death within 30 days following the operation. No patient died in the hospital or experienced valve related complications. One patient, however, underwent mitral valvuloplasty 3 months after the operation. Another patient died from intra-cranial hemorrhage in the 31st month after the operation. Therefore, the valve-related death rate was 4.3%, and the valve-related complication rate 8.6% on mid-term follow-up. 1, 3-, and 5-year valve- related event free rates were 90.8%, 79.5%, and 79.5%, respectively, while 1, follow-up. 1, 3-, and 5-year valve- related event free rates were 90.8%, 79.5%, and 79.5%, respectively, while 1, 3-, and 5-year survival rates were 100%, 88.8%, and 88.8%, respectively. Conclusion: The findings suggest that a complete removal of infected tissues is essential in the operative treatment of infectious endocarditis of the mitral valve. It is also suggested that when infected tissues are completely removed, neither type of material nor method of operation has a significant effect on the operation result. The postoperative results also suggest the need for a close follow-up observation of the patients suspected of having brain damage, which is caused by preoperative blood contamination or emboli from vegetation, for a possible cerebral vascular injury such as mycotic aneurysm.

• Journal of Preventive Medicine and Public Health
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• v.25 no.4 s.40
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• pp.413-428
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• 1992

The aim of this study was to evaluate the appropriateness of some kinds of surgery and admission, such as cesarean section (C/S), cholecystectomy, and pediatric pneumonia. For appropriateness evaluation, we ourselves developed some criteria, which were included in the category of explicit and linear criteria, with the assistance of specialists of relevant clinical field. The evaluation of appropriateness was performed by two family physicians. The major findings were as follows: 1. For cesarean section, 77.6% of deliveries were determined to be 'appropriate', but the level of appropriateness was not significantly different among hospitals and between hospital groups by size. The most freqeunt indication of C/S was repeated operation, followed by cephalopelvic disproportion (CPD). The labor trials for vaginal delivery among repeated C/S and CPD cases were performed in 24.5% of pertinent deliveries. 2. About 73.8% of cholecystectomy cases was appropriate to one of the surgical indications, without significant differences among hospitals. Of surgical indications, 'sufficiently frequent and intense symptom recurrence' was the most frequent, and 'confirmed acute cholecystitis' was the second. 3. Of children admitted due to pneumonia, only 57.4% of cases satisfied admission criteria, and the level of appropriateness of admission was different among hospitals. The common reasons fur admission were 'failure to initial treatment', 'suspected bacterial pneumonia', 'young infant', etc. We could find that there were differences of quality among hospitals in some procedures, especially in the pediatric pneumonia and labor trial before C/S, which suggested that the implementation of quality assurance activiteis would be necessary in this country. In this study, we used some simple and primitive research tools and the numbers of subjects and tracer procedures were limited. So advanced studios with plentiful subjects and more representative diseases or procedures should be tried.