• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.6
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• pp.20-28
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• 2021

High enthalpy test facilities, such as a shock tunnel, are to be operated at the specific pressure ratio according to the desired test condition. A metallic diaphragm is machined or a forced rupture device is used to open it at a specific pressure ratio. The diaphragm opening procedure takes several hundred microseconds including rupture and deformation. This process is expected to affect the test conditions. In this study, numerical simulation was performed for different materials, thicknesses, and opening ratios. And the characteristics of shock wave generation and the stagnation condition in the tube are investigated. Results show that the final opening ratio and rupturing procedure directly affect the speed of a shock wave, stagnation pressure, and test time.

• Journal of the Korean Arthroscopy Society
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• v.5 no.2
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• pp.135-139
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• 2001

Purpose : Repair of the posterior capsule tear at the time of the operation for the chronic postero-lateral or postero-medial rotary instability has not been reported. We describe the arthroscopic repair of the posterior capsule tear using the posterior trans-septal portal. Method : After conducting basic arthroscopic examination of the knee, postero-medial and postero-lateral portals are secure to make the posterior trans-septal portal, through which the postero-medial and postero-lateral capsule tears are repaired using the suture hook under the arthroscopic guidance. Conclusion : When arthroscopic reconstruction of PCL insufficiency or postero-lateral rotaty instability that accompanies postero-medial or postero-lateral capsular tears. rising the posterior traits-septal portal could ensure better visualization of the capsule and a subsequent more accurate repair of the capsule. Since it significantly lessened instability, it could contribute to an achievement of successful clinical results.

• Journal of the Korean Arthroscopy Society
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• v.9 no.1
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• pp.70-76
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• 2005

Purpose: We describe a new technique of arthroscopic repair with using autogenous hamstring tendon graft augmentation for the acute posterior cruciate ligament rupture. Operative technique: A routine arthroscopic examination of the knee joint is initially performed, then the posterior trans-septal portal is prepared with the using the posteromedial and posterolateral portals. The torn tibial stump that is retracted to the posterior compartment is repaired by a suture hook that is introduced through the anteromedial portal; visualization during this procedure is done with the arthroscope via the posteromedial portal. Using the retrieved suture, both suture ends are brought out to the anteromedial portal. The torn tibial stump is pulled to the intercondylar notch and then repaired with stitches at the anterior compartment. After the tibial and femoral tunnels are prepared without damaging the remnant PCL bundle, the combined torn PCL fibers and the autogenous single-bundle semitendinosus and gracilis tendon grafts are passed through the femoral tunnel and fixed together Conclusion: Arthroscopic repair of the torn tibial stump and autogenous hamstring tendon graft augmentation after preparing the tibial and femoral tunnels by using the trans-septal portal, without damaging the remnant PCL bundle, seems to be a very effective method for the treatment for acute PCL injuries, and especially for tears at the femoral attachment.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.1
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• pp.98-106
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• 2022

To develop reliable dual pulse rocket motor, vacuum ignition performance at high altitude and design stability for rupture pressure of the Pulse Separation Device(PSD) are required. In this study, rupture pressure analysis method for the membrane type PSD of the dual pulse rocket motor was developed. The PSD rupture pressure formulation was derived from strain-pressure relationships. The PSD vacuum rupture test apparatus and the PSD 1 second vacuum ignition test apparatus were developed, which can simulate the high altitude vacuum environment. Rupture pressure of PSD was analyzed by conducting the PSD vacuum rupture test, and design values of PSD were derived. Finally, vacuum ignition performance and rupture pressure of the designed PSD were validated with PSD 1 second vacuum ignition test.

• Journal of the Korean Institute of Gas
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• v.3 no.3 s.8
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• pp.51-57
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• 1999

A study on the vented gas explosion characteristics were carried out with the liquified petroleum gas(LPG) which is used in domestics and industries fuel. To evaluate a damage by gas explosion and to predict a explosion hazards, a series of experiment have been performed in the regular hexahedron vessel of 270${\iota}$. A side of the vessel was made to setting a polyester diaphragm which was ruptured by explosion to simulate an accidental explosion which ruptured the window by explosion. Experimental parameters were LPG concentration, ignition position, venting area, a strength of diaphragm which was ruptured and distances from venting, Experimental results showed that vented gas explosion pressure was more affected by the diaphragm strength than the gas concentration, and the vented gas explosion pressure and blast wave pressure was increased with decreasing the venting area and increasing the strength of diaphragm. In this research we can find that a damage by vented explosion at the outside can be larger than the inside by blast wave pressure near the venting.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.215-218
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• 2014

High combustion efficiency of hydrogen could make it an ideal source of green energy in the future. At this time, high pressure vessel is the most reasonable method of storing hydrogen. However, such a high pressurized vessel could pose a critical threat if ruptured. For this reason, it is important to understand the mechanism of hydrogen's self-ignition when a high-pressure hydrogen released into air. This paper presents several visualization images as experimental results using high-speed camera. From the visualization images, the ignition is initiated near rupture disk immediately after failure of disk. And the initial ignition and flame is stronger as a rupture pressure increases. However, this ignition region do not affect the general self-ignition mechanism when a high-pressure hydrogen is released into air through tue after failure of disk.

• Journal of the Korean Arthroscopy Society
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• v.4 no.2
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• pp.111-116
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• 2000

Purpose : We reviewed the results of arthroscopic posterior cruciate ligament reconstruction using Achilles tendon allograft, and the efficacy of the surgical technique using gradual tibial tunneling and posterior transseptal technique. Materials and Methods : From september 1997 to September 1999, 8 patients with complete PCL injury were treated by arthroscopic PCL reconstruction using Achilles tendon allograft. Mean follow-up period was 21.7 months. Mean preoperative posterior laxity was 14mm. The clinical outcome was assessed by Telos stress test, Lysholm knee score and IKDC score. Result : There was no complication such as infection and neurovascular injury. Posterior translation using Telos device was less than 5mm in 6 cases$(75\%)$, and between 6 to 10mm in 2 cases$(25\%)$. The mean Lysholm knee score was 45 preoperatively and improved to 87 postoperatively. In IKDC system, 2 of 8 patients were group A and 6 were group B. Conclusion : Arthroscopic PCL reconstruction using achilles tendon allograft and posterior transseptal technique shows reliable stability, short operative time and minimizing donor site morbidity but needs more long term follow-up.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.367-370
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• 2006

The ballistic range has long been employed in a variety of engineering fields such as high-velocity impact engineering, projectile aerodynamics, creation of new materials, etc, since it can create an extremely high-pressure state in very short time. Two-stage light gas gun is being employed most extensively. The present experimental study has been conducted to develop a new type of ballistic range which can easily perform a projectile simulation. The ballistic range consists of a high-pressure tube, piston, pump tube, shock tube and launch tube. The experiment is conducted to find out the dependence of various parameters on the projectile velocity. The pressure in high-pressure tube, pressure of diaphragm rupture and projectile mass are varied to obtain various projectile velocities. This study also addresses the effect of the presence of a shock tube located between the pump tube and launch tube on system study. The experimental results are compared with those obtained through an author's theoretical study.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.263-266
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• 2007

The ballistic range has long been employed in a variety of engineering fields such as high-velocity impact engineering, projectile aerodynamics, creation of new materials since it can create an extremely high-pressure state in very short time. Two-stage light gas gun is being employed most extensively. The present experimental study has been conducted to develop a new type of ballistic range which can easily perform a projectile simulation. The experiment is conducted to find out the dependence of various parameters on the projectile velocity. The pressure in high-pressure tube, pressure of diaphragm rupture and projectile mass and piston mass are varied to obtain various projectile velocities. The flow field is visualized to see flow around projectile.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.177-180
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• 2010

Two-stage light gas gun, sorted with Ballistic Range System, is used to research spray characteristics of supersonic liquid jets. When high pressure tube was pressurized to the 135 bar, diaphragm films which composed with OHP film are ruptured. Expansion gases accelerate a projectile approximately 250 m/s at the exit of pump tube. And accelerated projectile collides with liquid storage part and liquid jets were injected into supersonic conditions. Supersonic liquid jets show the multiple jets and generate shockwave at the forward region of jets. Supersonic liquid jets of speed and shockwave angle have different value at each case. Supersonic liquid jets with minimum velocities are injected with M=1.53 at the geometry condition of L/d=23.8.