• Journal of Power System Engineering
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• v.20 no.5
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• pp.78-85
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• 2016

This paper considers the influence of internal heat exchangers to the efficiency of a refrigerating system using R170. These liquid-gas heat exchangers(internal or suction-line heat exchangers) can, in some cases, yield improved system performance while in other cases they degrade system performance. A steady state mathematical model is used to analysis the performance characteristics of refrigeration system with internal heat exchanger. The influence of operating conditions, such as the mass flowrate of R170, inner diameter tube and length of internal heat exchanger, to optimal dimensions of the heat exchanger is also analyzed in the paper. The main results were summarized as follows : the mass flowrate of R170, inner diameter tube and length of internal heat exchanger, and effectiveness have an effect on the cooling capacity, compressor work and RCI(Relative Capacity Index) of this system. Exception for the effect of inner diameter, the RCI of R170 with respect to refrigerant mass flowrate, the length and effectiveness of internal heat exchanger is about 2.1~3.3% higher than that of R13 at the same experimental conditions. With a thorough grasp of these effect, it is necessary to design the R170 compression refrigeration cycle using internal heat exchanger.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.104-108
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• 1995

Von Mises stress and compliance distribution was evaluated using a finite element analysis on the anastomosis of an artery with length of 20mm, inner diameter of 4mm, thickness of 0.5mm and a PTFE graft with length of 5.7mm, Inner diameter of 2mm. thickness of 0.2mm. When anastomotic angle was taken as $45^{\circ}$ and inner pressure of $1330\;dyne/mm^2$ was applied inside the 2 conduits. From the analysis results were obtained as follows. (1)Artery diameter increased in both horizontal x and vertical y directions and the magnitude of that in x direction was bigger than in y direction. (2) The compliance was maximum on the anastomosis. especially on that with acute angle. This reduced approaching to the right or left end. (3) The equivalent stress was maximum on top in the y direction and winimum on the nodes around $110^{\circ}$ in circumferential direction from the top. (4) The equivalent stress was maximum in the vicinity of anastomosis with acute angle along the longitudinal direction of the artery. This trend was also observed along the PTFE graft.

• Journal of Biomedical Engineering Research
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• v.43 no.4
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• pp.193-198
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• 2022

Contrast enhanced magnetic resonance imaging using gadolinium-based contrast agent (GBCA) is a very useful in vivo technique to visualize the inner ear pathology including endolymphatic hydrops. Although systemic intravenous (IV) administration can visualize the perilymph space, the visualization was possible by indirect passage of contrast agent through blood-perilymph barrier. All animal experimental procedures were performed under anesthesia with 5% isoflurane. Lipopolysaccharide (LPS) was instilled into the left tympanic cavity through the tympanic membrane using a sterile 27gauge needle to induce hydrops model. Tucker-Davis Technologies system was used to measure Auditory Brainstem Responses (ABRs). For intracerebroven-tricular (ICV) administration, 25 µmol of GADOVIST (Bayer, Berlin, Germany) was used and diluted GADOVIST injection was 10 µl. MR imaging was acquired with a 9.4 Tesla MRI scanner. Transmit-receive volume coil with 40 mm inner diameter and 75 mm out diameter was used. ICV administration well demonstrated the strong enhancement along the cerebrospinal fluid (CSF) microcirculation pathway including CSF fluid in the subarachnoid space and CSF space of the inner ear structures. On the other hand, IV administration showed no contrast enhancement along the CSF microcirculation pathway and showed weak enhancement in the inner ear structures. In case of rat hydrops model, ICV administration showed that the reduced contrast enhancement in the perilymph space of the hydrops induced inner ear compared to the contrast enhancement in the perilymph space of the normal inner ear. New systemic ICV administration method provide contrast enhancement of GBCA in the inner ear through CSF microcirculation pathway.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.425-432
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• 2001

Single-phase heat transfer coefficients and pressure drops of R-22 were measured in smooth, horizontal copper tubes with inner diameters of 3.36 mm, 5.35 mm, 6.54 mm and 8.12 mm, respectively. The experiments were conducted in the closed loop, which was driven by a magnetic gear pump. Data are presented for the following range of variables: Reynolds from 1000 to 20000. Single-phase heat transfer coefficients increased by $10{\sim}30%$ as the inner diameter of tube was reduced and it was found that a well-known previous correlation, Gnielinski's correlation, was not suitable for the small diameter tubes. But the pressure drop in the small diameter tubes have been shown slightly deviations with Blauius' correlation. Based on an analogy between heat and mass transfer, the new heat transfer correlation is proposed to predict the experimental data successfully.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.943-948
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• 2000

The Twin-fluid Swirl Nozzles are used in many parts of the industry to produce homogeneous spray. This study is to investigate the effects of outer air swiller and inner water swiller on atomization of liquid.. The experiment was carried out with increasing air-flow rate at constant liquid-flow rate and with changing outer air swiller angle and inner water swiller angle. A Particle Dynamics Analyzer(PDA) was used to measure drop size, mean and ms values of axial velocity, number density and Sauter mean diameter(SMD). The axial mean velocity and SMD of droplets were measured along the center line and radial directions. It was found that the higher air flow-rate resulted in the smaller Sauter mean diameter of liquid spray and the higher axial mean velocity of droplets. This experimental results will be conveniently used for the preliminary design stage of twin-fluid nozzle development.

• Applied Microscopy
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• v.1 no.1
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• pp.27-34
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• 1969

The compound eyes of the adult Drosophila melanogaster were. fixed in 1.25 per cent glutaraldehyde and 1 per cent osmium tetroxide buffered with sodium cacodylate at pH 7.2. Double fixed specimens were dehydrated using the alcohol series and embedded in Epon 812. They were sectioned with porter blum and JUM 5B ultra-microtome and then stained with lead hydrooxide and uranyl acetate. All thin sections were examined with Hitachi HS-7 or HU-11 electron microscope. The rhabdomere of the compound eye is composed of numerous microvilli packed, arranged, and projected from inner edge of each retinal cell. Each microvillus consisted of a centrum, about $82{\AA}$ in diameter, surrounded by the substances, about $105{\AA}$ in width, which were bounded with double membrane about $44{\AA}$ in thickness. In each inner edge of the microvilli, there was a cylinder, about $175{\AA}$ in diameter, in parallel with retinal cells, which contained a cylindrical axis about $583{\AA}$ in diameter. The surface of the outer edges .of .the microvilli was bounded with reticullar substances about $500{\AA}$ in thickness.

• The Korean Journal of Zoology
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• v.5 no.1
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• pp.35-38
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• 1962

Two subspecies are known to Family Hylidae(Order Anura) in Korea : namely , Hylaarborea japonica GUENTHER and H.a.stepheni BOULENGER, and they have been hitherto distinguished as different subspecies from four characteristics : the rate of interorbital to incternasal length, the rate of diameter of tympanum to diameter of 3 rd finger disc, the rate of the length of inner metatarsal tubercle to diameter of 3 rd finger disc, and the rate of inner metatarsal tubercle to the length of lst toe. The author has compared the above to subspecies for the characteristics with 123 individuals collected from ten different localities in Korea and has found that their fluctation curves overlap each other. The author considers, therefore, that the four characteristics could not be assumed as keys for the classification of the two subspecies and has reached the conclusion that these two subspecies should be regarded as one subspecies and Hyla arborea japonica GUENTHER should be given to both of them as the subspecies name.

• Steel and Composite Structures
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• v.8 no.4
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• pp.297-312
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• 2008

A concrete filled double skin tubular (called CFDST in abbreviation) member consists of two concentric circular steel tubes and filled concrete between them. Purpose of this study is to investigate their bending characteristics experimentally. The two test parameters of the tubes considered were an inner-to-outer diameter ratio and a thickness-diameter ratio. As a result, their observed failure modes were controlled by tensile cracking or local buckling of the outer tube. Discussion is focused on the confinement effect on the filled concrete due to the both tubes and also the influence of the inner-to-outer diameter ratios on their deformability and load carrying capacity.

• Steel and Composite Structures
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• v.2 no.2
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• pp.129-146
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• 2002

This paper describes a series of compression tests carried out on concrete filled double skin tubes (CFDST). Both outer and inner tubes are cold-formed circular hollow sections (CHS). Six section sizes were chosen for the outer tubes with diameter-to-thickness ratio ranging from 19 to 57. Two section sizes are chosen for the inner tubes with diameter-to-thickness ratio of 17 and 33. The failure modes, strength, ductility and energy absorption of CFDST are compared with those of empty single skin tubes. Increased ductility and energy absorption have been observed for CFDST especially for those having slender outer tubes with larger diameter-to-thickness ratio. Predictions from several theoretical models are compared with the ultimate strength of CFDST stub columns obtained in the tests. The proposed formula was found to be in good agreement with the experimental data.

• Architectural research
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• v.23 no.1
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• pp.11-17
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• 2021

A concrete-filled circular steel tube beam was fabricated, and a bending test was performed to analyze its failure modes, displacement ductility, bending-shear strength, and load-central deflection relationship. For the bending test, the installation position of the shape memory alloy (SMA) inside and outside the double-skin steel tube was used, and the rebar installation position, the concrete strength, the mixing of fibers, and the inner-outer diameter ratio as the main parameters. The test results showed that the installation positions of the reinforcements inside and outside the double-skin steel tube and the inner-outer diameter ratio of the steel tube affected the ductility, maximum load, and failure mode. In general, the specimen made of general concrete with SMA installed outside and inside (OI) the double-skin steel tube showed the best results.