• Progress in Superconductivity and Cryogenics
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• v.9 no.2
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• pp.35-38
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• 2007

A single-stage and two-stage pulse tube refrigerators have been designed for cryopump application. The different diameters of pulse tube and regenerator have been investigated at single-stage pulse tube refrigerator(PTR). Experiments have been performed on single-stage PTR to reach minimum temperature with optimum valve opening at a few frequencies. And the two-stage pulse tube refrigerators have been assembled with tested single-stage pulse tube and tested. When orifice turn is opened to 9 and double inlet is opened to 3 at a single-stage, the lowest temperature of 33.7 K is achieved. The cooling capacity at single-stage is 38 W at temperature of 80 K. A two-stage pulse tube refrigerator has 16.3K at the second stage and 59.7K at the first stage. The cooling capacity achieved is 16.5 W at 80 K, the first stage and 0.6 W at 20 K, the second stage. Some details on the design of pulse tube refrigerator and the experimental apparatus are given.

• Journal of ILASS-Korea
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• v.1 no.4
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• pp.46-53
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• 1996

The present study is aiming at improving the performance of main nozzle of an air jet loom with a modified reed and auxiliary nozzles. The double coaxial pipe jets consisting of a central air jet and an annular air jet have been experimentally investigated. The duter jet has a potential core and a constant velocity. The inner jet through an inner long pipe is induced by the subatmospheric pressure near the inner nozzle edge, and the jet velocity of an inner pipe is always lower than that of a outer pipe. The static pressures of the main nozzle over a wide range of the nozzle tank pressure were measured, and the nozzle velocity and Mach numbers were analytically calculated. Experiment81 results indicate that the critical condition of Mach number of unity to occur at the two positions in a main nozzle; one of them is the needle tip and the other is the acceleration tube exit An increase in the tank pressure causes the critical throat condition to occur at the two positions above. The velocity of acceleration-tube exit is maximum at the critical length L* and flow patter in acceleration-tube over critical lengh remains unstable.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2182-2185
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• 1999

In this experimental study we propose the double dielectric barrier discharge(DDBD) reactor to produce as high an electric field as possible. DDBD reactor is designed to remove $NO_x$ at atmospheric pressures from the moving pollution source such as diesel automobile DDBD reactor consisted of two cylinder glass tubes arranged so that the gas flow was directed between the two tubes. Inside of the inner tube was filled with small metal beads and outside of the inner tube was wounded with stainless wire to form the electrode. The outer tube was surrounded by an aluminum foil In this reactor there are three electrodes, i.e. metal bead(C), helical wire(I) and aluminum foil(0). By using DDBD reactor we will report some interesting results of treatment of the gas which is the dilute mixtures of NO in N2. And then we compared thee results with the results of cylinder-wire(CW) which is one of popularly used reactor in non-thermal plasma applications.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.3
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• pp.91-100
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• 1996

Experimental results for forced convection condensation of non-azeotropic refrigerant mixtures inside a horizontal smooth tube are presented. The mixtures of R-22+R-134a and pure refrigerants R-22 and R-134a are used as the test fluids and a double pipe heat exchanger of 7.5mm ID and 4800mm long inside tube is used. The range of parameters are 100-300kg/h of mass flow rate, 0-1.0 of quality, and 0, 33, 50, 67, and 100 weight percent of R-22 mass fraction in the mixtures. The heat flux, vapor pressure, vapor temperature and tube wall temperature were measured. Using the data, the local and average heat transfer coefficients for the condensation have been obtained. In the same given experimental conditions, the liquid heat transfer coefficients for NARMs were considerally lower than that of the pure refrigerant of R-22 and R-134a. Local heat transfer characteristics for NARMs were different from pure refrigerant R-22 and R-134a. In some regions, local heat transfer coefficients for NARMs were increased in the following order ; Bottom$\rightarrow$Top$\rightarrow$Side. The condensation heat transfer coefficients for NARMs increased with mass velocity, heat flux, and quality, but were considerably lower than that of pure refigerant R-22 and R-134a.

• Journal of radiological science and technology
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• v.43 no.6
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• pp.489-494
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• 2020

The Law method is observing the temporal bone. There are two types of methods: the double angle method, which manipulates the center ray angle of the tube twice, and the single angle method, which manipulates once. The purpose is to increase the reproducibility of the image by making vertical incidence by making an assistive device using a 3D printer. Two assistive devices with a wedge-shaped 8.5 × 10 × 2.3 cm, an inclined surface of 7.5 cm, and an inclination angle of 15° were fabricated. Assistive devices can be combined with each other in the form of grooves, and PLA (Poly Lactic Acid) is used as a material. In the first experiment, 10 examiners operated the tube 15° in the caudad direction and 15° in the anterior direction, and measured it with a protractor to conduct a reproducibility experiment. Second, two examiners acquired vertically incidence images using the existing law method and assistive devices, and measured the distance between each measurement point to evaluate the reproducibility. The tube center ray angle reproducibility experiment was not statistically significant, but the angle difference was up to 9° between examiners. The reproducibility experiment of radiographic images was not statistically significant with the conventional method, and the method using an assistive device was statistically significant. Therefore, regardless of skill level, an image capable of securing reproducibility, which is the advantage of vertical incidence, could be obtained.

• Steel and Composite Structures
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• v.38 no.5
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• pp.547-562
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• 2021

This paper aims to explore the mechanical behavior and moment-rotation model of blind bolted joints between concrete-filled double skin steel tubular columns and steel-concrete composite beams. For this type of joint, the inner tube and sandwiched concrete were additionally identified as basic components compared with CFST blind bolted joint. A modified moment-rotation model for this type of connection was developed, of which the compatibility condition and mechanical equilibrium were employed to determine the internal forces of basic components and neutral axis. Following this, load transfer mechanism among the inner tube, sandwiched concrete and outer tube was discussed to assert the action area of the components. Subsequently, assembly processes of basic coefficients in terms of their stiffness and resistances based on the component method by simplifying them as assemblages of springs in series or in parallel. Finally, an experimental investigation on four substructure joints with CFDST columns for validation purposes was carried out to capture the connection details. The predicted results derived from the mechanical models coincided well with the experimental results. It is demonstrated that the proposed mechanical model is capable of evaluating the complete moment-rotation relationships of blind bolted CFDST column composite connections.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.6
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• pp.82-91
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• 2021

We compared the heat transfer characteristics of the parallel and the counterflow flow in the concentric double tube of the Al₂O₃/water nanofluids using numerical methods. The high- and low-temperature fluids flow through the inner circular tube and the annular tube, respectively. The heat transfer characteristics according to the flow direction were compared by changing the volume flow rate and the volume concentration of the nanoparticles. The results showed that the heat transfer rate and overall heat transfer coefficient improved compared to those of basic fluid with increasing the volume and flow rate of nanoparticles. When the inflow rate was small, the heat transfer performance of the counterflow was about 22% better than the parallel flow. As the inflow rate was increased, the parallel flow and the counterflow had similar heat transfer rates. In addition, the effectiveness of the counterflow increased from 10% to 22% rather than the parallel flow. However, we verified that the increment in the friction factor of the counterflow is not large compared to the increment in the heat transfer rate.

• Steel and Composite Structures
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• v.42 no.3
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• pp.325-351
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• 2022

This paper studies the lateral impact behavior of ultra-high performance fiber-reinforced concrete (UHPFRC) filled double-skin steel tubular (UHPFRCFDST) columns. The impact force, midspan deflection, and strain histories were recorded. Based on the test results, the influences of drop height, axial load, concrete type, and steel tube wall thickness on the impact resistance of UHPFRCFDST members were analyzed. LS-DYNA software was used to establish a finite element (FE) model of UHPFRC filled steel tubular members. The failure modes and histories of impact force and midspan deflection of specimens were obtained. The simulation results were compared to the test results, which demonstrated the accuracy of the finite element analysis (FEA) model. Finally, the effects of the steel tube thickness, impact energy, type of concrete and impact indenter shape, and void ratio on the lateral impact performances of the UHPFRCFDST columns were analyzed.

• Journal of Chest Surgery
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• v.32 no.8
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• pp.765-767
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• 1999

Tracheobronchial rupture following tracheal intubation is a rare complication. We experienced a case of tracheal rupture following double-lumen endotracheal tube intubation. A 76 year old female was admitted due to coughing and chest discomfort. The operation was performed with the diagnosis of congenital broncho esophageal fistula. During the operation, accidently the main trachea was ruptured longitudinally. There was no history of surgical trauma. The ruptured trachea was repaired with prolene and monofilament absorbable sutures. The cause of tracheal rupture was suspected overinflation of the cuff. The patient was discharged from the hospital without any significant complications.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.215-220
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• 2008

This study shows the results on thermal performance test with domestic solar collector for low-temperature applications using KS, then reveals the efficiency difference between KS and EN standard. Using the test results, this study presents the status of thermal performance with domestic solar collector including flat-plate, single evacuated, and double evacuated (with mirror or U-tube) solar collector.