• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.11-12
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• 2013

To investigate the effect of an inner diameter of the extension tube on the self-ignition when high pressurized hydrogen abruptly released through a tube, both experimental and numerical approach are used. The result show that there is a possibility to have successful ignition when the tube diameter is decreased even at the pressure that could not give sustainable flame with a larger diameter tube. Numerical simulation show the flame development inside the tube and weak and stretch flame spout the tube for 10.9 mm tube, whereas strong complete flame has been generated for 3 mm tube.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.2
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• pp.73-79
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• 2012

We developed the carbon fabric/EPDM chamber insulation in order to protect motor case with high intensity gas flow. A six-inch simulation motor connected with extension tube was designed to test ablation characteristic of insulation. High intensity gas flow was induced by a FRP disc with hole between motor and extension tube. After ground test, ablation depth of the carbon fabric/EPDM insulation was decreased compared to another insulations after ground static test.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.85-91
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• 2011

We developed carbon fabric/EPDM chamber insulation in order to protect motor case with high intensity gas flow. Six-inch simulation motor connected with extension tube was designed to test ablation characteristic of insulation. High intensity gas flow was induced by FRP disc with hole between motor and extension tube. After ground test, ablation depth of carbon fabric/EPDM insulation was decreased compared to another insulations after ground static test.

• Journal of Welding and Joining
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• v.14 no.5
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• pp.87-94
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• 1996

It has been well known in GMA welding process that wire feeding speed (WFS) or deposition rate increases linealy with the increase of wire extension. In this investigation, however, such an well-known relationship was .reconsidered in terms of contact-tube to work distance (CTWD) instead of wire extension. To verify the proposed relationship between WFS and CTWD, bead-on-plate welding was performed with various CTWDs in the range of 15∼35mm under the condition of near-constant voltage and current As expected, the test results showed an excellent linear relation between WFS and CTWD. Furthermore, the value of the slope turned out to be quite similar to those of previous investigators obtained either theoretically or experimentally through the Precise measurement of electrode extension. Present result also demonstred that the increase of CTWD could be very practical measure for increaring deposition rate without any increase of heat input Depending on the tip recess the practical maximum of CTWD was appeared to be limited somewhere in 25∼30mm mainly due to the entrappment of porocity.

• Korea-Australia Rheology Journal
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• v.11 no.4
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• pp.293-304
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• 1999

Refinements of classical theories for entangled or crosslinked polymeric systems have led to incommensurable models for rubber networks and polymer melts, contrary to experimental evidence, which suggests a great deal of similarity. Uniaxial elongation and compression data of linear and branched polymer melts as well as of crosslinked rubbers were analyzed with respect to their nonlinear strain measure. This was found to be the result of two contributions: (1) affine orientation of network strands, and (2) isotropic strand extension. Network strand extension is caused by an increasing restriction of lateral movement of polymer chains due to deformation, and is modelled by a molecular stress function which in the tube concept of Doi and Edwards is the inverse of the relative tube diameter. Up to moderate strains, $f^2$ is found to be linear in the average stretch for melts as well as for rubbers, which corresponds to a constant tube volume. At large strains, rubbers show maximum extensibility, while melts show maximum molecular tension. This maximum value of the molecular stress function governs the ultimate magnitude of the strain-hardening effect of linear and long-chain branched polymer melts in extensional flows.

• Journal of Chest Surgery
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• v.18 no.3
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• pp.529-533
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• 1985

Though esophageal cancer was not a common disease, early metastasis and direct extension to adjacent organ were important on the treatment of disease. Therefore, palliative operation was often useful in advanced esophageal cancer. Between June 1985 through July 1985, we treated three cases of inoperable esophageal cancer with Celestin`s endo-esophageal tube by esophageal intubation. Three operations were done under general anesthesia. Celestin`s tube were inserted via oral cavity and additional traction on stomach were applied. After complete insertion of tube was done, the distal end of Celestin`s tube was modified in length. Also stay suture was applied between tube and stomach wall was applied. Postoperative esophagogram revealed good esophageal patency through Celestin`s tube. Clinically, swallowing difficulty was much improved after operation.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.264-266
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• 2006

This traveling wave tube amplifier maintenance system was developed for performance of microwave Surveillance radar traveling wave tube amplification parts, and field operation. The Maintenance system is traveling wave tube amplification part RF output waveform measurement and HVPS Voltage adjustment and a maintenance function are offer. The system was developed as an embedded system base it consisted of Linux os which applied a top-down design and visual technique. Therefore change and easy extension of a system. This paper discussed characteristic of maintenance equipment function, composition, and an employment program.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.98-103
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• 2003

This paper presents phenomena of vibration and noise due to acoustic resonance in tube bank of a HRSG. Acoustic resonance is may arise when the vortex shedding frequency coincides with the acoustic natural frequency. At this tube bank, dominant frequencies of vibration in this system were 43.5, 67.5㎐. The 3$\^$rd/ acoustic natural frequency calculated was 68.5㎐. When the difference of vortex shedding frequency and acoustic natural frequency is within ${\pm}$20%, acoustic resonance could occur. In this system, in order to prevent acoustic resonance, acoustic baffle was installed in the tube bank before operating. But acoustic resonance occurred. So, we evaluate the effect of acoustic mode due to baffle extension length. After investigating, we did revise acoustic baffle to eliminate acoustic resonance effectively.

• Korean Journal of Medicinal Crop Science
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• v.21 no.5
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• pp.348-352
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• 2013

This study was carried out to investigate the effect of sucrose, boric acid, and calcium nitrate in optimum pH and relative humidity on pollen germination and pollen tube growth of boxthorn (Lycium chinense M.). Medium containing 100mg/L of $H_3BO_3$ showed maximum pollen germination and pollen tube elongation, 64.8% and $920{\mu}m$. Additionally supplied calcium nitrate to the medium lowered pollen germination rate and pollen tube elongation. Here we report the optimum conditions for the pollen germination and pollen tube development was observed at 10% sucrose, 1.0% agar, pH 6.0, and 100% relative humidity.

• Korean Journal of Computational Design and Engineering
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• v.9 no.2
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• pp.143-147
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• 2004

To design parts satisfying physical property in the continuous region, we do it in the discrete rectangular mesh points. Then we obtain points data from parts design and usually construct the surface using least squares method. In such case, that surface has an oscillation in the ineffective region which is inadequate for physical phenomena or NC machining. To solve both problems simultaneously, we extend the surface smoothly to have small curvature in the extended region. Up to now, we use the least squares method for the parts design in Color Picture Tube or Color Display Tube but in this paper, we use functions which is easily controllable. This surface has no error within the effective region compared to the least squares method.