• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1125-1146
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• 2018

Segment lining applied to the TBM tunnel is mainly made of concrete, and it requires sufficient structural capacity to resist loads received during the construction and also after the completion. When segment lining is design to the Limit State Design, both Ultimate Limit State (ULS) and Service Limit State (SLS) should be met for the possible load cases that covers both permanent and temporary load cases - such as load applied by TBM. When design segment lining, it is important to check structural capacity at the joints as both temporary and permanent loads are always transferred through the segment joints, and sometimes the load applied to the joint is high enough to damage the segment - so called bursting failure. According to the various design guides from UK (PAS 8810, 2016), compression stress at the joint surface can generate bursting failure of the segment. This is normally from the TBM's jacking force applied at the circumferential joint, and the lining's hoop thrust generated from the permanent loads applied at the radial joint. Therefore, precast concrete segment lining's joints shall be designed to have sufficient structural capacity to resist bursting stresses generated by the TBM's jacking force and by the hoop thrust. In this study, bursting stress at the segment joints are calculated, and the joint's structural capacity was assessed using Leonhardt (1964) and FEM analysis for three different design cases. For those three analysis cases, hoop thrust at the radial joint was calculated with the application of the most widely used limit state design codes Eurocode and AASHTO LRFD (2017). For the circumferential joints bursting design, an assumed TBM jack force was used with considering of the construction tolerance of the segments and the eccentricity of the jack's position. The analysis results show reinforcement is needed as joint bursting stresses exceeds the allowable tensile strength of concrete. This highlights that joint bursting check shall be considered as a mandatory design item in the limit state design of the segment lining.

• Journal of Chest Surgery
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• v.31 no.7
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• pp.660-667
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• 1998

Background: This study is to evaluate the effectiveness and application of Lecompte procedure as a treatment for various complex cardiac anomalies with pulmonary outflow tract obstruction. Methods: Between July 1988 and December 1997, 44 patients underwent Lecompte procedure in Seoul National University Children's Hospital. The male to female ratio was 24 to 20 and the mean age was 29.2 months(range, 3 to 83). Of these patients, 28(63.6%) had transposition of great arteries with ventricular septal defect and pulmonary stenosis(or pulmonary atresia), 14(31.8%) had double outlet right ventricle with pulmonary stenosis(or pulmonary atresia), and so on. The principles of the technique are 1) extension of the ventricular septal defect or conal resection, 2) construction of a intracardiac tunnel connecting the left ventricle to the aorta, and 3) direct connection, without a prosthetic conduit, of the pulmonary trunk to the right ventricle. Results: There were 3 in-hospital deaths and their causes were sustained hypoxia, myocardial failure, and sepsis, respectively. There was 1 late death due to sepsis. Reoperations were performed in 6 patients who had pulmonary outflow tract obstructions(4 cases), residual muscular ventricular septal defect(1 case), and recurrent septic vegetation(1 case). The cumulative survival rates by the Kaplan-Meier method were 92.7%, 92.7%, and 92.7% at 1, 2, and over 4 years. The reoperation free survival rates were 92.7%, 92.7%, and 70.2% at 1, 3, and over 5 years. Among the risk factors for the operative death, aortic cross clamping time had statistical significance(p<0.05) and all the risk factors for the recurrent pulmonary stenosis such as age, pulmonary artery index, and materials used for the pulmonary outflow tract reconstruction had no statistical significance(p>0.05). Conclusions: Our review suggests that Lecompte procedure is an effective treatment modality for various complex cardiac anomalies with pulmonary outflow tract obstruction. Repair in early age is possible and the rates of mortality and morbidity are also acceptable.

• Journal of the Korean Arthroscopy Society
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• v.7 no.2
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• pp.169-175
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• 2003

Purpose : The purpose was to evaluate the early result of revision of failed anterior cruciate ligament (ACL) reconstruction. Materials and Methods : From August 1997 to February 2002, this report presents the findings of 18 patients who had revision surgery for failed ACL reconstruction. There was an average of 39 $(7\~120)$months from index procedure to the time of revision. Allografts were used in 14 $(78\%)$cases and autografts were used in 4 $(22\%)$cases and the revision procedures were assisted by arthroscopic technique. The majority of chief complaints were instability in 16 $(89\%)$cases. Sixteen $(89\%)$ cases had 1 previous reconstruction, 2 $(11\%)$ cases had 2. Before and after revision, patients were evaluated by Lachman test, pivot shift test, KT 2000, radiographs, Lysholm score and HSS score and subjective satisfaction. Results : Average length of followup was 27 $(12\~60)$months. Preoperatively, all cases were positive in Lachman test and pivot shift test. After revision the majority of cases were negative. Objectively improving stability was confirmed by KT 2000 and all average KT 2000 was 7.75 $(3.5\~12.5)$mm preoperatively and 2.36 $(1.0\~6.0)$mm at final followup. Lysholm score and HSS score were also improved from 72.6 $(66\~77)$ and 72.5 $(68\~78)$ preoperatively to 89.2 $(80\~92)$ and 88.2 $(81\~92)$ at final followup. Most $(89\%)$ of patients were satisfied with their results. The most common causes of failed ACL reconstruction were malposition of femoral tunnel in 11 $(61\%)$cases. Conclusion : Arthroscopic revision ACL surgery with adequate graft for failed ACL reconstruction was successful in objectively and subjectively improving stability. However, considering the most common causes of failure after ACL reconstruction were errors in surgical technique, it is important that the primary ACL reconstruction should be performed with correct surgical technique.