• Journal of Fisheries and Marine Sciences Education
• /
• v.5 no.2
• /
• pp.119-127
• /
• 1993

This work studies for heat transfer and pressure drop performance of integral inner and outer fin tubes, designed to enhance the heat transfer performance of smooth tubes for in recipro and turbo refrigerator or high performance compact heat exchangers. Eight different inner spiral fin copper tubes with integral fin at outside surfaces were employed to improve boiling heat transfer coeffcient. For comparison, tests were made using a plain tube having the inside diameter and an outside diameter equal to that at the root of the fins for the finned tubes. Pool boiling heat transfer is investigated experimentally and theoretically on single tube arrangement. The refrigerant evaporates at a saturation state of 1 bar on the outside tube surface heated by hot water. The refrigerant R11 ($CFCl_3$) was used at a pressure of $P_s=1bar$ as a convenient test fluid with a boiling temperature of $T_s=23.6^{\circ}C$. The observed heat transfer enhancement of boiling for finned tubes significantly exceeded that to be expected on grounds of increased area. The maximum Vapor - side enhancement(i.e., vapor - side heat transfer coefficient of finned tube/vapor - side coefficient for plain tube) was found to be around 4 at 1299fpm - 30grooves tube.

• Advances in pediatric surgery
• /
• v.1 no.2
• /
• pp.162-169
• /
• 1995

Since 1988, we have performed esophageal replacement with the reversed gastric tube on four esophageal atresia patients. Three patients had long-gap esophageal atresias and one patient had recurrent tracheoesophageal fistula that was previously operated on three times. One combined imperforate anus. The youngest patient was 6-month-old and the oldest, 34-month-old at the time of procedure. The technique of gastric tube construction is described. There have been both major and minor complications. Although two patients had shown distal tube strictures as late complications. those were solved with tuboplasties on 29 months and 48 months, postoperatively. Growth and development have been acceptable in all four patients, although most remain in the lower percentiles for growth and height, a condition that usually predates the esophageal substitution. Conclusively, reversed gastric tube interposition has proved very satisfactory for long-gap esophageal atresia that cannot be anastomosed primarily even by spiral myotomy and esophageal atresia with recurrent tracheoesophageal fistula having destroyed esophagus due to previous operation.

• Solar Energy
• /
• v.18 no.2
• /
• pp.145-152
• /
• 1998

In this experimental study, for obtaining the data to be used in the increased recover rate of waste heat from the recirculated sand, the furan foundry sand were used as the fluidized particle in the fluidized bed in which the smooth, spiral and finned tubes($Do={\varphi}12.7$) were horizontally installed and used as the heat-transfer tubes. The heat transfer experiments were performed in the conditions of water Reynolds number of inside tubes in the range of 4,000 to 18,000 and particle Reynolds number of outside tube in the range of 0.8 to 7.5. The heat-transfer coefficients(ho) increase as the higher inside temperature of the fluidized bed and the maximum heat-transfer coefficients can be obtained in the range of 3.5 to 5.5 of particle Reynolds number in the all tubes. The maximum Nu numbers of smooth, spiral and finned tubes are figured as about 1:1.5:3 in order even if the ratios show little different as the temperatures of bed.

• Proceedings of the KSR Conference
• /
• 2001.05a
• /
• pp.241-248
• /
• 2001

The ductility of circular hollow reinforced concrete columns with one layer of longitudinal and spiral reinforcement placed near the outside face of the section and the steel tube placed on the inside face of the section is investigated. Such hollow sections are confined through the wall thickness since the steel tube is placed. The results of analytical moment-curvature analyses for such hollow sections are compared with those for the circular section with the sane diameter. In this study, moment-curvature analyses are conducted with Mandel's confined concrete stress-strain relationship in which the effect of confinement is to increase the compression strength and ultimate strain of concrete. The moment-curvature analyses confirmed that the ductility is primarily influenced on the ultimate strain. The variables influenced on the ultimate strain is the ratio and yield strength of confining reinforcement and the compression strength for confined concrete. From this ultimate strain - the transverse reinforcement ratio relationship, the transverse reinforcement ratio for circular hollow reinforced columns with confinement is proposed. The proposed transverse reinforcement ratio is confirmed by experimental results.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.3
• /
• pp.459-468
• /
• 2020

This study established a new polymerase spiral reaction (PSR) that combines with reverse transcription reactions for HCV detection targeting 5'UTR gene. To avoid cross-contamination of aerosols, an isothermal amplification tube (IAT), as a separate containment control, was used to judge the result. After optimizing the RT-PSR reaction system, its effectiveness and specificity were tested against 15 different virus strains which included 8 that were HCV positive and 7 as non-HCV controls. The results showed that the RT-PSR assay effectively detected all 8 HCV strains, and no false positives were found among the 7 non-HCV strains. The detection limit of our RT-PSR assay is comparable to the real-time RT-PCR, but is more sensitive than the RT-LAMP. The established RT-PSR assay was further evaluated for detection of HCV in clinical blood samples, and the resulting 80.25% detection rate demonstrated better or similar effectiveness compared to the RT-LAMP (79.63%) and real-time RT-PCR (80.25%). Overall, the results showed that the RT-PSR assay offers high specificity and sensitivity for HCV detection with great potential for screening HCV in clinical blood samples.

• Publications of The Korean Astronomical Society
• /
• v.15 no.spc1
• /
• pp.1-13
• /
• 2000

We review the early historical developement of astronomical spectrographs, properties of emission line spectra of HII regions in spiral galaxies, and absorption line features of galactic globular clusters. Emission line spectra of HII regions within three spiral galaxies NGC 300, NGC 1365, and NGC 7793, which were observed from AAT/IPCS, had been analysed, and we discuss the abundances of elements in HII regions and the radial abundace gradients through the galaxies. The radial UBV color variations of two globular clusters, NGC 1851 and NGC 2808, were examined for correlations with radial variations of several absorption lines in the integrated spectra, which were obtained from SAAO 74 inch telescope and image tube spectrograph. Nine giant star's spectra in NGC 3201 were also obtained and analysed for the radial abundance gradients in the globular cluster. The results show that the presence of a radial color gradient in a globular cluster is correlated with the presence of abundance gradients. Finally, we suggest some scientific programs for the new high dispersion spectrograph, which will be installed to the BOAO 1.8m telescope.

• Transactions of Materials Processing
• /
• v.16 no.8
• /
• pp.621-628
• /
• 2007

Nowadays, Exhaust Gas Recirculation(EGR) Cooler is one of the most favorite systems for reducing the generation amount of $NO_x$ and other particle materials from vehicles burning diesel as fuel. Efficiency of the system is mainly dependent on its heat transfer efficiency and this ability is affected by net heat transferring area of the system. For that reason, several types of heat transfer tube such as dimple, wrinkle and spiral types that have large net area are used. However, it is difficult to manufacture the rectangular tube with dimpled type structure because it experiences too much strain around the rectangular tube surface during the forming process. For that reason, in this study, numerical simulation for forming process of non-symmetric dimple shape on a thin sheet metal was carried out. Furthermore, theoretical forming limit curves(forming limit diagram, forming limit stress diagram) were proposed as criteria of formability evaluation. From the results of finite element simulation in view of stress and strain distribution, it is found that the designed process has robustness and feasibility to safely manufacture the dimpled rectangular tube.

• Steel and Composite Structures
• /
• v.20 no.4
• /
• pp.731-748
• /
• 2016

Pile-to-pilecap connection performance is important as Integral abutment bridges (IABs) have no expansion joints and their flexible weak-axis oriented supporting piles take the role of the expansion joint. This connection may govern the bridge strength and the performance against various lateral loads. The intention of this study is to identify crack propagation patterns when the pile-to-pilecap connection is subjected to lateral loadings and to propose novel connections for improved performance under lateral loadings. In this study, eight different types of connections were developed and modeled, using Abaqus 6.12 to evaluate performances. Three types were developed by strengthening the connections using rebar or steel tube: (i) PennDOT specification; (ii) Spiral rebar; and (iii) HSS tube. Other types were developed by softening the connections using shape modifications: (i) cylindrical hole; (ii) reduced flange; (iii) removed flange; (iv) extended hole; and (v) slot hole connection types. The connections using the PennDOT specification, HSS tube, and cylindrical hole were shown to be ineffective in the prevention of cracks, resulting in lower structural capacities under the lateral load compared to other types. The other developed connections successfully delayed or arrested the concrete crack initiations and propagations. Among the successful connection types, the spiral rebar connection allowed a relatively larger reaction force, which can damage the superstructure of the IABs. Other softened connections performed better in terms of minimized reaction forces and crack prevention.

• Journal of Korean Society of Steel Construction
• /
• v.16 no.5 s.72
• /
• pp.529-541
• /
• 2004

Concrete filled steel tube structures were recently used in constructing high-rise buildings due to their effectiveness. Studies on concrete filled steel tubes have been focused on the experiments of uni-axial compression and bending and eccentric compression. There were also a few studies that investigated CFT member behavior under combined compression and torsion. The behavior of a circular CFT column under combined torsion and compression was theoretically investigated, considering the confinement of steel tubes on the concrete, the softening of the concrete, and the spiral effect, which were the dominant factors that influenced compression and torsion strength. The biaxial stress effects due to diagonal cracking were also taken into account. By applying those factors to compatibility and equilibrium conditions, the basic equation was derived, and the equation could be used to incorporate the torsional behavior of the entire loading history of the CFT member.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.11 no.1
• /
• pp.105-109
• /
• 1987

Artificial roughness as a means of improving heat transfer gains more interest, especially for application to various heat exchanger. This study present experimental information for single-phase free and force convection heat transfer in a circular tube containing a internal spiral ribs. To examine the effect of inclined angle of tube, it was varied from 0 deg to 90 deg (0.deg., 22.5.deg., 45.deg., 90.deg.) with horizontal. Length of tube is 1.6m, and width, height and helix angle of rib are 4.2mm, 1.5mm, and 60 deg respectively. Water was used as a working fluid and test piece was heated with a constant heat flux by electric heater. Experiments have been performed with the range of modified Grashof number from 2 * 10$^{6}$ to 15 * 10$^{6}$ for free convection and with the range of Reynolds number from 3,000 to 40,000 for forced convection. Since the increase in heat transfer coefficients influence directly to the friction coefficient of the tube, the changes of the friction factors are also presented for several different cases considered in this investigation.