• Journal of Chest Surgery
• /
• v.35 no.2
• /
• pp.149-152
• /
• 2002

We report successful application of dual trachcobronchial stcnt to the diffuse tracheal stenosis. An one-month-old boy was transferred to the emergency room due to tachypnea and respiratory difficulty with COB retention. Preoperative computed tomography revealed pulmonary artery sling with diffuse tracheal stenosis. We found that the diameter of the both main bronchus was less than 3mm and the trachea was a complete ring. We divided the left pulmonary artery and implanted it to the main pulmonary artery under cardiopulmonary bypass. After that, tracheoplasty was performed with autologous pericardium. However, after the initial measures, CO2 retention and respiratory difficulty persisted due to the granulation tissue and dynamic obstruction of the airway ensued by the overlying pericardial flap. Therefore, we decided to apply a single tracheal stunt. After the insertion of tracheal stent, residual stenosis of the both main bronchus opening continued to cause respiratory difficulty Finally we applied dual tracheobronchial stent and resolved the airway obstruction.

• Journal of the Korea Society of Computer and Information
• /
• v.19 no.2
• /
• pp.161-171
• /
• 2014

In this paper the flow dynamics of the flue gas equipment in the desulfurization system was numerically analyzed by simulating the problems for the turbulent and combustion flow from Induced Draft Fan(I.D.Fan) outlet to Booster Up Fan(B.U.Fan) inlet using the commercial CFD software of CFD-ACE+ in CFDRC company for Computational Fluid Dynamic Analysis. The guide vane of this section was examined for the minimum pressure loss and the uniform flow dynamic to B.U.Fan with the proper velocity from I.D,Fan exit to B,U,Fan inlet section at the boiler both the maximum continuous rating and the design base. The guide vanes at I,D.Fan outlet and B.U.Fan inlet were removed and modified by numerical simulation of the CFD analysis. The flue gas at the system had the less pressure loss and the uniform flow dynamics of the flow velocity and flow line by comparing with the old design equipment.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.11
• /
• pp.1022-1027
• /
• 2007

Experimental and computational studies on a turbopump inducer with and without a bearing strut were performed to evaluate the effects of a strut on the performance of an inducer. Head rise, efficiency and surface static pressures were measured and compared with computational results. Generally a good agreement is observed between experimental and computational results, but some discrepancies are observed due to complex flow features such as backflows at the inlet and strut/inducer interactions. For the flow rates where the backflow region is large, installing a strut enhanced the hydraulic performance of the inducer by diminishing the size of the backflows. The results also show that the strut has negligible effect on the suction performance of the inducer.

• Journal of the Korean Arthroscopy Society
• /
• v.11 no.1
• /
• pp.63-68
• /
• 2007

Purpose: The authors introduce a new technique of arthroscopic all inside repair using anterolateral and anteromedial portals for lateral meniscus root complete radial tear in patients who underwent concurrent anterior cruciate ligament (ACL) reconstruction. Operative technique: Arthroscope is placed through anteromedial portal and suture hook ($Linvatec^{TM}$, Largo, Florida, USA) is delivered through anterolateral portal. By rotating the suture hook, it penetrates posterior horn of the torn meniscus from femoral to tibial surface for vertical orientation. PDS No. 1 ($Ethicon^{TM}$, Somerville, NJ, USA) is delivered through the suture hook, and then it is withdrawn. Both end of PDS No. 1 are taken out through the anterolateral portal. MAXON 2-0 ($Syneture^{TM}$, Norwalk, Connecticut, USA) is used to penetrates remnant of tibial attachment of the torn meniscus from tibial to femoral surface in a same manner. MAXON 2-0 is changed for PDS No. 1 from tibial to femoral surface by shuttle relay technique. PDS No. 1 is tied using SMC (Samsung Medical Center) knot. Conclusion: All inside repair is a useful technique to achieve anatomical repair and to restore the hoop tension in lateral meniscus root complete radial tear.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.05a
• /
• pp.77-81
• /
• 2008

The local regression rate behavior of solid fuel in swirl injection hybrid rocket were studied. In generally, axial injection regression rate was tending to be decrease with axial distance, beyond which increased with increasing axial distance from the leading edge. On the other hand, swirl injection regression rate was high at the leading edge of the fuel and comparatively uniform regression rate at the downstream. Overall regression rate of swirl injection was increased about 54% for the overall regression rate of axial injection. Through this study, it was found that using swirl injector was useful in applying to the small sounding rocket.

• Tribology and Lubricants
• /
• v.2 no.2
• /
• pp.12-19
• /
• 1986

Using emulsion lubricant whose cooling effect and incombustibility are good and which is economical, I investigated lubricative mechanism and the behavior of scattered particles in the elastic fluid lubrication region with the line contact between rollers and plates and the light interference system. The results of the study are as follows: (1) The flow in the squeeze oil film is considered as comparatively wide clearance and narrow one, and in the former case the effect of the distribution of particles and the velocity on the flow. In the latter case, emulsion particles stay in the clearance an the oil film changes with the decrease of the oil film thickness. (2) In the wide clearance the velocity difference of the flow O/W or W/O emulsion is inverse proportional to the particle size. In the narrow clearance the distribution of the remained drops is different from one another and the scattered particles change more easily in O/W type than in W/O type. (3) At the beginning of the EHL the stagnation region with slow flowing velocity exists and the behavior at the region is different depending on the particle size. (4) By observing the dischromatic light interference line, emulsion oil passing through EHL region and the crack behavior at the beginning of EHL were found.

• The Journal of Engineering Geology
• /
• v.19 no.3
• /
• pp.401-408
• /
• 2009

Old national Road No. 59 that connects Danyang and Gagok has 35 dangerous cut slopes. It is relatively narrow and has a poor alignment. The torrential rains in 2002 and 2006 has caused numerous slope collapses, landslides and road settlements in this area. The old road's high risk level lead to the planning and construction of a new national road. During the construction of the new road in December 2006, the right side of Dugcheon Tunnel entrance has collapsed and tension cracks were observed on the district road above the tunnel. In order to determine the cause of failure, intensive field investigation and monitoring cracks were performed together with Lower Hemisphere Projection Analysis, Limit Equilibrium Analysis and Finite Difference Analysis.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.7
• /
• pp.581-588
• /
• 2014

The inlet/outlet flow in the tube-side of the shell and tube heat exchanger was experimentally measured to investigate the effect of the porous baffle on uniform flow distribution. A 1/3rd scale-downed model of a heat exchanger was used and particle image velocimetry was applied for measuring the instantaneous velocity vector fields. The absolute errors in the flow rate were calculated and compared for the tube-side with and without the porous baffle, by varying the flow rate from 60 to 90 LPM. The results revealed that the porous baffle can improve flow uniformity and reduce the absolute error in the flow rate of the model with the baffle by about 74%, compared to that without the baffle. This result can be used for improving the performance and design of the shell and tube heat exchanger.

• The Journal of Engineering Geology
• /
• v.20 no.2
• /
• pp.147-153
• /
• 2010

Cut-off wall with a low permeability can be constructed to prevent groundwater seepage in spillway tunnel areas. Three spillway tunnels are constructed in Im-ha multipurpose dam region and three types of cut-off walls with a variety of directions and scales are designed. As a result of MODFLOW modeling to assess the effect of cut-off wall for three types, groundwater inflows to the tunnels range from 64.26 $m^3/day$ to 65.49 $m^3/day$ and also they through a cut-off wall section from a reservoir do from 44.08 $m^3/day$ to 45.31 $m^3/day$ and it does not show any significant difference among them. Therefore, a construction process and an environmental conservation rather than the effectiveness of cut-off wall need to be considered to select the best cut-off wall in this region.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.6
• /
• pp.869-876
• /
• 2008

A thermocompressor is the equipment which compresses a vapor to a desired discharge pressure. Since it was first used as the evacuation pump for a surface condenser, it has been widely adopted for energy saving systems due to its high working confidence. In the present study, the geometrical analysis of the shape between the jet nozzle and the diffuser inlet, the drag force was calculated by means of the integrated equation of motion and the computational fluid dynamic (CFD) package called FLUENT. The computer simulations were performed to investigate the effects by the various suction flow rates, the distance from jet nozzle outlet to the diffuser inlet and the dimensions of the diffuser inlet section through the iterative calculation. In addition, the results from the CFD analysis on the thermocompressor and the experiments were compared for the verification of the CFD results. In the case of a jet nozzle, the results from the CFD analysis showed a good agreement with the experimental results. Furthermore, in this study, a special attention was paid on the performance of the thermocompressor by varying the diffuser convergence angle of $0.0^{\circ}$, $0.5^{\circ}$, $1.0^{\circ}$, $2.0^{\circ}$, $3.5^{\circ}$ and $4.5^{\circ}$. With the increase of the diffuser convergence angle. the suction capacity was improved up to the degree of $1.0^{\circ}$ while it was decreased over the degree of $1.0^{\circ}$.