• Archives of Reconstructive Microsurgery
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• v.8 no.2
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• pp.130-138
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• 1999

The lower extremity injuries are extremely increasing with the development of industrial & transportational technology. For the lower extremity injuries that result from high-energy forces, particularly those in which soft tissue and large segments of bone have been destroyed and there is some degree of vascular compromise, the problems in reconstruction are major and more complex. In such cases local muscle coverage is probably unsuccessful, because adjacent muscles are destroyed much more than one can initially expect. Reconstruction of the lower extremity has been planned by dividing the lower leg into three parts traditionally The flaps available in each of the three parts are gastrocnemius flap for proximal one third, soleus flap for middle one third and free flap transfer for lower one third. Microvascular surgery can provide the necessary soft tissue coverage from the remote donnor area by free flap transfer into the defect. Correct selection of the appropriate recipient vessels is difficult and remains the most important factor in successful free flap transfer. Vascular anastomosis to recipient vessels distal to the zone of injury has been advocated and retrograde flow flaps are well established in island flaps. Retrograde flow anastomosis could not interrupt the major blood vessels which were essential for survival of the distal limb, the compromise of fracture or wound healing might be prevented. During 5 years, from March 1993 to Feb. 1998, we have done 68 free flap transfers in 61 patients to reconstruct the lower extremity. From analysis of the cases, we concluded that for the reconstruction of the lower extremity, free flap transfer yields a more esthetic and functional results.

• Journal of Veterinary Clinics
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• v.25 no.1
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• pp.1-8
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• 2008

This study is conducted to compare ultrasonographs with plain radiographs in monitoring bone regeneration during reconstruction of critical sized radial defects in dogs. A 15 mm bony defect was taken on each of the eight dog's radius using an electrical saw and an external fixator was applied. The experimental groups were divided into non-treated group(group 1) and $Osteoset^{(R)}$-treated group(group 2). Each fracture site was evaluated using plain radiography and ultrasonography. Radiographic callus formation occurred after $11.50{\pm}1.12$ days in group 1 and $11.50{\pm}0.5$ days in group 2. Neovascularized flow signal could be seen $6.50{\pm}1.5$ days and the vascular signal disappeared after $45.00{\pm}6.16$ days after operation in group 1. Neovascularized flow signal was observed $6.75{\pm}1.78$ days and vascular signal disappeared $23.25{\pm}3.03$ days after surgery which was caused by acoustic shadowing in group 2. Early stages of regeneration were observed more clearly with color Doppler ultrasonography than with plain radiography. Also from the results it is concluded that color Doppler ultrasonography are useful in observing initial stages of bone repair.

• Transactions of Materials Processing
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• v.13 no.5
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• pp.422-428
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• 2004

At present, the design of extrusion dies and operation in extrusion companies are primarily based on trial and error. The experience of the die designer, the press operator and the die corrector determine the performance of the extrusion die and the efficiency of the process. In order to produce defect-free products of desirable quality in terms of strength, surface quality and geometrical dimensions, it is important to obtain more knowledge of the processes that occur during extrusion. Recently, to reduce the costs of designing and manufacturing of extrusion dies, and to ensure the quality of the extruded products, numerical simulation for extrusion processes such as FEM (finite element method) is applied increasingly and becomes a very important tool for the design and development of new products. However, most of the studies about FE simulation have been accomplished for simple geometry and low extrusion ratio in the filed of steady metal flow conditions. The extruded products of AI alloy in industrial practice involve complicated sectional geometry. This study was designed to reduce the time of die design and manufacturing in the extrusion process using FEM simulation. FEM simulations of extrusion process were performed in non-steady states conditions by changing weld plate included in extrusion die set. Product which was employed in this study is heat sink that has been used in the parts of heat exchanger of electric circuits. It is generally applied for aluminum or its alloys due to heat efficiency and easy production of complicated shapes, and manufactured by extrusion process. The simulated results showed that weld plate shape in extrusion dies influences meta] flow and dimensional accuracy of products.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1133-1143
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• 2016

The purpose of this study is to improve project performance analysis indicators for BTL sewer rehabilitation projects. Among the assessment indicators for BTL sewer rehabilitation projects, an infiltration assessment indicator is given a high score of 17.5 points as a single assessment item. This infiltration assessment indicator is assessed focusing on the amount of infiltration, and presently calculated according to 'Nighttime Domestic Flow Evaluation' method. However, this assessment indicator's failure to reflect the geological features of Jeju region is emerging as a problem in the operational stage. Thus, this study intended to compare and analyze the calculation result depending on the assessment indicators and the actual amount of infiltration, centering on Jeju region. To this end, this study analyzed the amount of infiltration in five areas of Jeju Province calculated according to 'Nighttime Domestic Flow Evaluation' method. Also, a complete enumeration survey was carried out about the conditions for actual infiltration occurrence. According to the results of this survey, ground water level is distributed lower than the level of sewer pipes. The results of a sewer pipe function test show there was no infiltration occurrence caused by sewer pipe defect. So, it is concluded that 'Nighttime Domestic Flow Evaluation' method, which is utilized for the current assessment indicator, is not appropriate to apply to Jeju region, and it is thought that there is a need to establish infiltration criteria specialized for Jeju region.

• Journal of Chest Surgery
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• v.21 no.2
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• pp.211-222
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• 1988

Tetralogy of Fallot is a cyanotic congenital heart disease characterized by large ventricular septal defect[VSD] and stenosis of right ventricular outflow tract[RVOT] and the degree of RVOT stenosis and the state of pulmonary arteries are the major determinant of prognosis of this anomaly after operation. The sum of blood flow through RVOT and collateral flow from systemic arteries determine the total pulmonary blood flow and it is drained to left atrium and left ventricle. Therefore the degree of development of left ventricle not only reflects pulmonary blood flow and the status of peripheral pulmonary arteries but also affects postoperative prognosis as a systemic ventricle. In this article, left ventricular volume and its influence on postoperative cardiac function in tetralogy of Fallot were studied in 34 patients operated on at Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital in 1985. Mean age of the patients was 5 1/12*3 9/12 years[range 9/12 - 14 8/12 years], mean body surface area[BSA] 0.65*0.20m2[range 0.38 - 1.22m2], mean body weight 15.6k6.48kg[range 7.0 - 36kg]and mean hematocrit 50.6*9.77%[range 32.0 - 73.5%]. Left ventricular end-diastolic volume[LVEDV] of them were from 11.2 to 113cc and there was a good linear correlation between BSA[m2, X]and LVEDV[cc, Y][Y= - 20.0+923x, r= 0.84, p < 0.005]. Mean LVEDV/m2 was [57.6 * 18.3 cc / m2[range 28.7 - 95.8 cc / m2] and there was a significant reduction of volume compared with normal value. As body surface increases, there was a increasing tendency in LVEDV/m2 but there was no statistical significance. Mean total amount of postoperatively infused dopamine in these 33 patients[except one who expired postoperatively] was 65.6*74.5mg / kg and it was 40.6*44.0mg / kg in routine RVOT widening group [Group I] and 205*49.3mg / kg in transannular RVOT widening group[Group II]. There was a statistically significant difference between two groups. In group I patients there was a good linear inverse correlation between dopamine total amount[mg / kg, Y] and LV volume[cc / m2, X] [Y = 150 - 1.89 X, r = - 0. 77, p < 0.005]. But there were no correlations between dopamine total amount and Hct, cardiopulmonary bypass time and aorta cross clamp time. In conclusion, the patient with small preoperative left ventricular volume required more amount of dopamine as an inotropic agent for the maintenance of a cardiac function in postoperative period. But this is a result of immediate postoperative period and does not reflect the long term effect of left ventricular volume in tetralogy of Fallot. There must be more study for the evaluation of its long term effect.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.50-50
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• 2009

In this paper, the plasma doping is performed on p-type wafers using $PH_3$ gas(10 %) diluted with He gas(90 %). The wafer is placed in the plasma generated with 200 W and a negative DC bias (1 kV) is applied to the substrate for 60 sec under no substrate heating. the flow rate of the diluted $PH_3$ gas and the process pressure are 100 sccm and 10 mTorr, respectively. In order to diffuse and activate the dopant, annealing process such as rapid thermal annealing (RTA) is performed. RTA process is performed either in $N_2$, $O_2$ or $O_2+N_2$ ambient at $900{\sim}950^{\circ}C$ for 10 sec. The sheet resistance is measured using four point probe. The shallow n+/p doping profiles are investigated using secondary ion mass spectromtry (SIMS). The analysis of crystalline defect is also done using transmission electron microscopy (TEM) and double crystal X-ray diffraction (DXRD).

• Journal of the Korean Society for Precision Engineering
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• v.33 no.6
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• pp.469-475
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• 2016

In this work, casting processes, such as filling and solidification, were simulated in order to accurately predict volume shrinkage defects in large-sized sand gravity casting. Turbulent flow of melted materials and a difference of solidification speed can cause volume shrinkage defects. In order to solve this problem and to understand the phenomenon, a porous filter application was studied. Two different porosities of 10 and 20 p.p.i filters were introduced into the gating system, and in view of the results so far achieved, the defect was dramatically reduced by 22%, compared to that without the use of the filter.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2954-2966
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• 1994

The characteristics and good corrosion resistance at room and elevated temperatures led to increasing application of Ti-alloys such as aircraft, jet engine, turbine wheels. In forging of Ti-alloy at high temperature, die chilling and die speed should be carefully controlled because the flow stress of Ti-alloy is sensitive to temperature, strain and strain-rate. In this study, the forging of turbine disk was numerically simulated by the finite element method for hot-die forging process and isothermal forging process, respectively. The effects of the temperature changes, the die speed and the friction factor were examined. Also, local variation of process parameters, such as temperature, strain and strain-rate were traced during the simulation. It was shown that the isothermal forging with low friction condition produced defect-free disk under low forging load. Consequently, the simulational information will help industrial workers develope the forging of Ti-alloys including 'preform design' and 'processing condition design'. It is also expected that the simulation method can be used in CAE of near net-shape forging.

• Journal of Chest Surgery
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• v.17 no.3
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• pp.381-388
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• 1984

Cor triatriatum is rare congenital cardiac anomaly first described by Church in 1868. The anomaly consists of an abnormal partitioning of the left atrium by a fibromuscular membrane that divides the atrium into an upper chamber, which receives the pulmonary veins, and a lower chamber, which contains the atrial appendage and the mitral valve. The upper and lower chambers communicate through a stenotic fenestration in the membrane, which has the hemodynamic consequence of pulmonary venous obstruction. Recently we experienced cot triatriatum associated with partial anomalous pulmonary drainage to right atrium. The upper chamber was connected to right atrium through a sinus venous type of ASD and received left superior and both inferior pulmonary vein, whereas the lower chamber so called true left atrium communicated with right atrium through foramen ovale type of ASD, left atrial appendage and mitral orifice. And the anomalous membrane has no fenestrations which permit blood flow. The operation was made right atrial approach under the CPB. We excised completely the anomalous septum and reconstructed atrial septal defect with pericardial patch to drain the right upper pulmonary vein to the left atrium. The postoperative course has been good during follow up.

• Journal of the Korean Society of Combustion
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• v.10 no.2
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• pp.1-8
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• 2005

Incomplete combustion due to quenching in a narrow confinement has been a major problem for realization of a reliable micro combustion device. In most micro combustors, effects of flows are absent in the quenching because the flow is laminar and no severe stretch is present. In such circumstance, quenching is caused either by heat loss or by removal of active radicals to the wall surface of the confinement. An experimental investigation was carried out to investigate the relative significance of these two causes of quenching of a premixed flame. A premixed jet burner with a rectangular cross section at the exit was built. At the burner exit, the flame stands between two walls with adjustable distance. The gap between the two walls at which quenching occurs was measured at different wall surface conditions. The results were analyzed to estimate the relative significance of heat loss to the wall and the removal of radicals at the surface. The measurements indicated that the quenching distance was independent of the wall surface characteristics such as oxygen vacancy, grain boundary, or impurities at low temperature. At high temperature, however, the surface characteristics strongly affect the quenching distance, implying that radical removal at the wall plays a significant role in the quenching process.