• Journal of Chest Surgery
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• v.36 no.12
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• pp.961-969
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• 2003

The purpose of this study was to evaluate the fate of left atrioventricular valve regurgitation(LAVVR) following repair of complete atrioventricular septal defects (AVSDs). Material and Method: Between July 1984 and March 2002, repair of complete AV defects were performed in 77 patients. Mean age at surgery was 30.23$\pm$69.11 months (range 1 to 456). Echocardiograms of all survivors after isolated AVSDs correction were reviewed. LAVVR were evaluated with color doppler echocardiography in 64 survival periodically. On each study, LAVVR severity was graded on a 1 to 4 scale, based upon the size of the regurgitated jet. Result: Mild deterioration of LAVV function was fairly common. LAVVR severity increased by >1 grade in 19 patients (30.2%) during the course of the study. However, the deterioration in LAVVR function occurred primarily between 12 and 24 months postoperatively. After the initial 24 postoperative months, LAVVR worsened on only 8 occasions and in each instance worsened by only 1 grade. Deterioration more than 3+ LAVVR occurred in only 3 patients. And deterioration to 4+ LAVVR was not observed after the initial 24 postoperative months but one. Survival curve analysis predicted a 88.2% of ten-year freedom rate from development of 4+ LAVVR after initial operation of complete AVSDs. Conclusion: Postoperative LAVVR remains fairly stable following AVSDs repair, Serious deterioration is rare after 24 postoperative months, especially after the initial 48 postoperative months. But serial follow-up study with echocariogram was need till 24 postoperative months after repair of complete AVSDs.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.97-97
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• 2009

The use of thin plate increases due to the need for light weight in large ship. Thin plate is easily distorted and has residual stress by welding heat. Therefore, the thin plate should be carefully joined to minimize the welding deformation which costs time and money for repair. For one effort to reduce welding deformation, it is very useful to predict welding deformation before welding execution. There are two methods to analyze welding deformation. One is simple linear analysis. The other is nonlinear analysis. The simple linear analysis is elastic analysis using the equivalent load method or inherent strain method from welding experiments. The nonlinear analysis is thermo-elastic analysis which gives consideration to the nonlinearity of material dependent on temperature and time, welding current, voltage, speed, sequence and constraint. In this study, the welding deformation is analyzed by using thermo-elastic method for PCTC(Pure Car and Truck Carrier) which carries cars and trucks. PCTC uses thin plates of 6mm thickness which is susceptible to welding heat. The analysis dimension is 19,200mm(length) * 13,825mm(width) * 376mm(height). MARC and MENTAT are used as pre and post processor and solver. The boundary conditions are based on the real situation in shipyard. The simulations contain convection and gravity. The material of the thin block is mild steel with $235N/mm^2$ yield strength. Its nonlinearity of conductivity, specific heat, Young's modulus and yield strength is applied in simulations. Welding is done in two pass. First pass lasts 2,100 second, then it rests for 900 second, then second pass lasts 2,100 second and then it rests for 20,000 second. The displacement at 0 sec is caused by its own weight. It is maximum 19mm at the free side. The welding line expands, shrinks during welding and finally experiences shrinkage. It results in angular distortion of thin block. Final maximum displacement, 17mm occurs around welding line. The maximum residual stress happens at the welding line, where the stress is above the yield strength. Also, the maximum equivalent plastic strain occurs at the welding line. The plastic strain of first pass is more than that of second pass. The flatness of plate in longitudinal direction is calculated in parallel with the direction of girder and compared with deformation standard of ${\pm}15mm$. Calculated value is within the standard range. The flatness of plate in transverse direction is calculated in perpendicular to the direction of girder and compared with deformation standard of ${\pm}6mm$. It satisfies the standard. Buckle of plate is calculated between each longitudinal and compared with the deformation standard. All buckle value is within the standard range of ${\pm}6mm$.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.1
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• pp.39-47
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• 2016

Repair methods of aging concrete pavement are generally used composite structure pavements, such a composite structure is subjected to a large impact on the mechanical behavior and ensure long-term commonality integrated under vehicle loads, environmental loads of the public in accordance with the bond strength between old and new concrete. A common of bonded concrete overlays that are currently available is Interface arrangements using a variety of equipment to ensure the excellent bond strength between old and new concrete than standard concrete, mixed with a material such as a polymer in order to improve the adhesion with the material itself. However, these method of constructions are being applied, depending on the developer site presents no special specifications apply when a specific application criteria objectively, this is due to the situation of each individual method, which is based on the difficulty in quality control of the site manager. In this study by performing a field test for polymer content via the variables that contribute most significantly to ensure bond strength and the field element core of the interface processing method and materials to ensure bond strength between the old and the new concrete, it was to derive the construction site construction method that can improve the performance of the bond strength through a review of the construction around the correlations and the bond strength according to the effective performance analysis of the conventional surface treatment process and variation of polymer volume fraction.

• Journal of Chest Surgery
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• v.32 no.7
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• pp.628-636
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• 1999

Background: Recent advances in understanding the anatomy of the complete atrioventricular septal defect(including right-dominant unbalanced atrioventricular septal defect) have led to alternative methods of repairing these defects. Material and Method: From May 1997 to July 1998, 8 consecutive infants(age range, 2 to 28 months, mean body weight 6.0$\pm$2.2 kg) received a single-stage intracardiac repair of the complete atrioventricular septal defect with modified surgical methods. Depending on the specific anatomic structure, the procedure was simplified in 3 patients by a direct closure of the ventricular element of the defect(Group I). Two patients judged unsuitable for direct closure due to a potential left ventricular outflow tract obstruction had received a standard two-patch repair(Group II). The remaining 3 patients with right-dominant unbalanced complete atrioventricular septal defect underwent biventricular repair; to enlarge the orifice of the left atrioventricular valve, the ventricular septal patch was placed slightly more to the right of the ventricular crest, a left sided bridging leaflet was augmented with an autologous pericardial patch, and the leaflet was repaired with a double- orifice(Group III . Result: In all 8 patients, the postoperative echocardiography demonstrated good hemodynamics. Seven patients were weaned from the ventilators after a mean 3$\pm$1 days, and 1 patient was weaned after 24 days due to a reoperation and emphysematous lung problem. A reoperation was performed in 1 patient for progressive left atrioventricular valve regurgitation due to leaflet tearing. There were no early and late mortalities. At the time of the latest review, judging from the echocardiographic criteria, left atrioventricular valve stenosis was mild in 1 patient(mean pressure gradient 6.5 mmHg, 13.5%), left atrioventricular valve regurgitation was absent or grade I in 7 patients(87.5%). The right atrioventricular valve regurgitation was absent or grade I in all 8 patients(100%). Conclusion: Infants with complete atrioventricular septal defect were treated with either a simplified approach with direct closure of the ventricular element of the defect or a modified surgical technique for a right-dominant unbalanced atrioventricular septal defect, depending on the anatomic structure. The results were no operative mortalities and low morbidity.

• Journal of Chest Surgery
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• v.40 no.8
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• pp.536-545
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• 2007

Background: Compared to adult patients, mitral regurgitation in pediatric patients is uncommon and it shows a wide spectrum of morphologic abnormalities. We retrospectively evaluated the midterm results of mitral valve repair in pediatric patients. Material and Method: Between December 1993 and August 2006, mitral valve repair was performed in 35 patients who were aged less than 18 years, The mean age was $5.3{\pm}5.3$ years and the mean body weight was $20,0{\pm}16.3\;kg$. 18 patients had associated cardiac anomalies. The most common pathologic finding was leaflet prolapse (n=17). The most common method of repair was the double orifice technique (n=15). Result: There was no early mortality. Eight patients underwent reoperation (24.2%), and five of them required mitral valve replacement. Among the four ring annuloplasty cases, two have developed mitral stenosis. Four out of the 14 double orifice cases required reoperation. One case of early mortality and one case of late mortality occurred in the reoperation cases. The 5-year survival rate and the freedom from reoperation rate were $93.3{\pm}4.6%$ and $76.1{\pm}8.2%$, respectively. The 5-year freedom from mitral valve replacement rate was $83.6{\pm}6.7%$. There was no significant risk factor for reoperation. Conclusion: The midterm results of mitral valve repair are very acceptable in pediatric patients compared to the adult cases, although the reoperation rate is slightly higher.

• Journal of Chest Surgery
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• v.40 no.11
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• pp.727-732
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• 2007

Background: The reciptents of aortic valve replacement or a Bentall operation usually display various degrees of mitral regurgitation. When deciding whether or not to correct the mitral regurgitation, one must consider its severity, underlying causes and operative risk. Recently, the operation method for correcting the concomitant mitral regurgitation has been done through aortic root to reduce the operation time and the cardiac trauma. We report our experiences that transaortic mitral valve commissuroplasty done with aortic valve replacement or a Bentall operation has been a simple, less invasive, effective method in the operative management of mitral valve regurgitation without significant organic changes. Material and Method: Between June 2002 and June 2005, twenty patients under-went mitral valve commissuroplasty via the aortic root with aortic valve replacement (n=14) or a Bentall operation (n=7). The mitral valve regurgitation of the patients didn't exceed a moderate (grade 2) degree and there was no significant organic disease. The preoperative diagnosis of MR was established by TTE and intraoperative TEE, and the patients were followed postoperatively by TTE. The operative technique was a simple anterolateral commissuroplasty of the mitral valve with a single mattress suture via the transaortic annular approach after excision of the aortic valve leaflets. Result: The mean patient age was 56.2 years and 65% (n=13) were male. The preoperative MR was mild (grade 1) in 9 (45%), mild to moderate in 8 (40%), and moderate (grade 2) in 3 (15%) patients. There were no operative mortalities. The MR improved in all patients (p=0.002) and the left ventricular ejection fraction (LV EF) improved in 14 (70%) patients (p=0.005). The mean cross-clamp time for the patients who under- went aortic valve replacement with transaortic mitral repair was $62.1{\pm}13.9 min$ and this was $137.5{\pm}7.2 min$ for the patients who underwent a Bentall operation with transaortic mitral repair. Conclusion: For selected patients without significant mitral organic disease, transaortic mitral valve commissuroplasty combined with aortic valve replacement or a Bentall operation may be a feasible, effective method without adding significant aortic cross clamping time and more cardiotomy.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.78-80
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• 2014

Silicone structural glazing (SSG) is a method utilizing a silicone adhesive to attach glass, metal, or other panel material to the structure of a building. Windload and other impact loads on the facade are transferred from the glass or panel through the silicone structural sealant to the systems' framework. Silicone structural glazing systems are currently a very common method of glazing throughout the world. Locally, structural silicone glazing has become very common to achieve aesthetically pleasing and high utilization of small land for both residential and commercial building. Although structural silicone glazing has been utilized for approximately thirty years in Korea, the understanding of its technology was low and limited. Consequently, Korean projects experienced many quality issues during assembly and construction, even in very recently finished buildings. Adhesion loss and water infiltration occurred on more than one project, and the time and cost to repair these issues were substantial. In general, there are two kinds of structural silicones depending on fabrication methods. 1part structural silicone is for site glazing system and 2part structural silicone is for unitized factory glazing system. In this paper, 2part structural silicone which is very common for factory fabricating curtainwall systems was evaluated with regards to various mixing ratio. Since the structural performance of 2part sealant can be affected by mixing ratios, some extra ranges of recommended mixing ratio were evaluated to see any performance differences. Besides on cure profile, comparative evaluations for mechanical properties and adhesion develop on common building substrates were conducted.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.227-237
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• 1998

In case the systems have radioactivity, toxic liquid or expensive fluid, and have to be performed repair work at one point of the system pipe, the formation of an internal ice plug by the removal of heat from the pipe is often consideredas a useful method. In this procedure, an annular jacket is placed around the pipe, and the jacket is then filled with liquid Nitrogen(-196.deg. C). Thermal analysis by the finite element method based on the laboratory experiments has been constructed. The result of the finite element analysis on the experimental model shows to be reasonable, and thus the finite element analysis for different pipe size, material and thickness has been performed to see if the ice plugging procedure in various applications can be safely performed without possibility of damage to the pipe. It has been confirmed that in carbon steel pipes the maximum stress is found around the boundary of the freezing jacket, and the stress increases as pipe thickness increases, but the maximum stress shows no consistency along the increment of the pipe diameter. The maximum stresses appear lower than yield stress in carbon steel. It has been also shown that in stainless steel pipes the maximum stresses are also found around the boundary of the freezing jacket, but almost the same value in spite of different pipe size an thickness, and the maximum stresses show slightly higher than the yield stress of the stainless steel.

• Journal of Chest Surgery
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• v.33 no.1
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• pp.20-25
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• 2000

Background: Median sternotomy remains the standard approach used by surgeons for most intracardiac operations but the residual scar is cosmetically unsatisfactory. To avoid an unsightly midline scar we have tried to use alternative skin incision (bilateral subm-ammary skin incision) to median sternal skin incision, In this study we have tried to compare different postoperative results of wound between two different skin incisional methods. Material and Method: Between June 1997 and June 1998, a bilateral subma-mmary skin incision combined with vertical sternotomy was performed in 21 pediatric female patients (submammary group)to repair acyanotic congenital heart disease. after the period we carried out a retrograde study about postoperative wound states comparing this incision with median sternal skin incision controls in whom there were 23 pediatric pat-ients (control group). Result: Patients' age ranged from 14 to 96 months(mean 38.2 months) Mean duration of subcutaneous drains using Hemovac which was used only in the patients of submammary group was 4.2 days and total amount of the drained effusion was 51.1 ml. Postoperative wound complications included wound eruption in one patient wound disruption in one patient and skin necrosis in 3 patients in submammary group and included wound disruption in 4 patients in controls. mean duration required for wound healing was 15,5 days in submammary group versus 10.4 days in controls. The mean scar length was 12.5 cm in submammary group versus 11.3 cm in controls. The average follow-up was 8.2 months in submammary group versus 9.0 months in controls. In submammary group 3 patients parents(14.3%) were pleased with their cosmetic results of wound scar but 8(38.1%) were dissatisfied. Among the 23 patients in control group 8(34.8%) were pleased but 8(34.8%) complained ofunhappiness with the scar.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.195-202
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• 2006

Deterioration of sewer concrete is representative that biochemical corrosion according to the $H_2S$ has growth by inhabit sulfur-oxidzing bacteria because of special environment in sewer. But in case of domestic, fundamentally, sulfur-oxidzing bacteria could moderate development of repair material method is need because of corrosion prevent method is inconsideration with carry out to improve project. In this paper, after development of spread type antibiotic with antibio-metal, antibacterial performance about sulfur-oxidzing bacteria of antibiotic and tested to estimate fundamental properties of bonding strength, abrasion contents, contents of water absorption, contents of air permeability, carbonation depth, chloride ion penetration depth and chemical resistance of spread with antibiotic restorative mortar.