• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.5
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• pp.74-80
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• 2013

This paper presents the transient behavior of the switching surge voltages generated by interruption of DC ground fault currents flowing through metal flexible conduits. All fault circuits consist of line parameters such as resistance, inductance, capacitance and conductance. The use of nonmagnetic metal conduits should be taken into account in order to reduce the inductance of battery charger distribution circuits. The frequency-dependent circuit parameters of metal flexible conduits were measured. The switching surge voltages generated at the ground fault circuit consisted of steel-galvanized alloy and aluminium conduits were investigated. As a result, the impedances of metal flexible conduits are significantly increased over the range of the frequency above 10 kHz and the switching surge voltages generated along aluminium flexible conduit are lower than those along steel-galvanized alloy conduit when DC fault current is interrupted.

• Journal of the Korean Solar Energy Society
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• v.24 no.3
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• pp.27-38
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• 2004

A numerical investigation has been carried out for a solar system, which consists of all glass solar vacuum tubes Water is heated as it flows through the coaxial fluid conduit inserted in each tube. The space between the exterior of the fluid conduit and the glass tube is filled with antifreeze solution. This is to facilitate heat transfer from the solar heated absorber surface to water and to prevent the functional problems due to freezing in frigid weather conditions. A one-dimensional steady state model is fully described which will be used to develop three-dimensional model using STAR-CD. These models could be used efficiently in designing all-glass solar collector tubes with different geometrical parameters other than those considered in the present analysis. Results show good agreement when compared with other experimental data demonstrating the reliability of the present model.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.567-570
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• 2006

A numerical study has been carried out for a solar water heater which consists of double skin solar vacuum tubes. Water is heated as it flows through the coaxial fluid conduit inserted in each tube. The space between the exterior of the fluid conduit and the glass tube is tilled with antifreeze solution. This is to facilitate heat transfer from the solar heated absorber surface to water and to prevent the functional problems due to freezing in frigid weather conditions. A one-dimensional steady state model is fully described which will be used to develop three-dimensional model using STAR-CD. These models could be used efficiently in designing double skin solar collector tubes with different geometrical parameters other than those considered in the present analysis. Results show a good agreement when compared with other experimental data demonstrating the reliability of the one-dimensional model employed.

• BMB Reports
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• v.30 no.2
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• pp.106-112
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• 1997

The effect of cryopreservation on extracellular matrix was studied with the ultimate objective of permiting a prediction of the tendency of aorta conduit tissue to calcify following transplantation. Cryopreserved and fresh porcine aorta conduit tissues were extracted using guanidine-hydrochloride (Gdn-HCl) followed by sequential digestion of the tissues with collagenase, elastase, and papain. Glycosaminoglycans (GAGs) of the proteoglycans (PGs) were isolated and quantitated. Gdn-HCl extracted about 61% and 62% of the total GAG (proteoqlycan) material from cryopreserved and fresh tissues, respectively. Collagenasesolubilized proteoglycans from Gdn-HCl extracted tissue represented 20% and 13%, respectively, of the total GAGs present in cryopreserved and fresh tissues. Subsequent elastase hydrolysis of collagenase-digested tissue released about 11% of total GAGs from cryopreserved tissue and 16% from fresh tissue. The remaining 8%, from cryopreserved tissue, and 9%, from fresh tissue, of the total GAGs were obtained after using a papain hydrolysis. There was essentially no difference between fresh and cryopreserved tissues in the relative distribution of proteoglycans in the extracts and digestions except in the initial digestion step where more proteoglycans were obtained from collagenase solubilization of cryopreserved tissue than fresh tissue (p<0.05). The histologic status of the fresh and cryopreserved porcine aortic conduit did not differ markedly. The normal tissue architecture was not affected markedly by the cryopreservation procedure as neither alteration of elastic structure, fibrous proteins nor alteration of nuclear distribution or smooth muscle cell morphology was detected. Quantitative tissue mineral studies revealed that the mean calcium content of the cryopreserved aorta conduit tissue $(165{\pm}3\;{\mu}g/g\;wet\;tissue)$ was higher than that of the fresh tissue $(105{\pm}4\;{\mu}g/g\;wet\;tissue)$ $(p<0.05)$. The mean phosphorus content was $703{\pm}35\;{\mu}g$ wet tissue from cryopreserved tissue and $720{\pm}26\;{\mu}g$ wet tissue from fresh tissue. The study indicates that there is no significant alteration in the distribution of PGs in properly cryopreserved tissue, but the total calcium level appears to be increased in tissue cryopreserved by the cryopreservation process used in this study.

• Magazine of the Korean Society of Agricultural Engineers
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• v.12 no.3
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• pp.2029-2034
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• 1970

This research was attempted to study on the effects of desalinization by the depth and interval of open conduit in Kang-Hwa polder where is located at the Kil-sang Myun, Kang-Hwa Gun, Kyung-gi Do, and it has been continued for the three years from 1967 to 1969. The results obtained are as follows; 1. The depths of saline expulsion by supplying of irrigation water are approximately 30cm to 50cm under the ground surface, but saline expulsion is hardly done in case of the depth which is deeper than the above mentioned, because the moisture and saline content hardly change in such a condition. 2. The speed of vertical percolation gradually decreases below the 30cm depth, but it is noticed that there is a tendency to make the percolation of the horizental direction from its layer in Kang-Hwa reclaimed tidal land. 3. Comparing experimental treatments-varing depths and intervals of open conduits, the interval of open conduit has a more effect upon the promotion of desalinization and increasing of the rice yields than the depth of it. Therefore, according to the results of experimental data, the optimum depth of open conduit is about 0.9m, the effective interval of it is about 18m. 4. Considering the loss of arable area by the layout of open conduit, the reasonable interval of it could extend to 36m.

• Journal of Chest Surgery
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• v.38 no.5 s.250
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• pp.382-384
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• 2005

Background: It is very difficult to choose the ideal valved conduit used in right ventricle outflow reconstruction in child. We can use the cryopreserved homograft but there is a limit of application because of its difficulties in the size matching and supply capacity. The $Shelhigh^{(R)}$porcine-valved conduit is commercially available and used as an alternative choice in these days. We report two cases of early Shelhigh conduit failure in right ventricular outflow tract after Ross operation in congenital aortic stenosis.

• Journal of Chest Surgery
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• v.25 no.11
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• pp.1327-1336
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• 1992

Between Jan. 1986 and Aug. 1992. 72 patients underwent Rastelli procedure. There were 43 male and 29 female, aged 46 days to 16 years [mean age, 5.2 years] with 18 patients less than 2 years of age. All patients had complex defect, 27 pulmonary atresia with ventricular septal defect, 18 corrected transposition of great arteries with pulmonary atresia or punmonary stenosis, 10 truncus arteriosus, 10 double outlet right ventricle with pulmonary atresia or stenosis, 7 complete transposition of great artersia with pulmonary atresia or pulmonary stenosis. The types of extracardiac valved conduit used were prosthetic valve[n=47, 24 car-bomedics, 19 Ionescu-Shiley, 4 Bjork-shiley] and hand-made trileaflet valve using pericardium. [n=23, 20 bovine pericardium, Z autologous pericardium, 1 equine pericardium] The mean size of valved cinduit was 5.25mm larger in diameter than the size of main pulmonary artery. [normalized to the patient`s body surface area] There were 17 hospital death[24%] and 4 late deaths[5.6%]. Postoperative complication rate was 38.9%a, none of which was conduit-related. All patients were followed pos-toperatively for 1 to 73 months. [mean 25.8 months] During follow-up period, reoperation was done in 6 patients due to stenosis of valved conduit. Mean interval between intial repair and reoperation was 20.3 months. In our experience, li recently extracardaic valved conduits between right ventricle [or pulmonary ventricle] and pulmonary artery were inserted with increasing frequency in infants less than 2 year, but hospital mortality was decreased, 2] Risk of reoperation due to conduit stenosis is low, so that the effect of graft failure on overall survival is minimized. 3] Nevertheless, because any type of extracardaic valved conduit is not ideal in children, we recommended that Lecompte should be done if cardiac anatomy is permitted.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.4
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• pp.38-45
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• 2002

This paper describes the technical issues of the domestic standard and guideline for lightning protection systems in order to propose the countermeasures in damage of computer and electronic equipments due to lightning surges. The relationship between the current flow in the down conductor and the current flow in the steel conduit surrounding the down conductor was investigated as a function of the installation method of down conductors. Also the experiments were conducted to evaluate the influences of the skin effect on the down conductor systems. As a result, when the down conductor were bonded to the steel conduit, the down conductor and the steel conduit act as one conductor, so much mure lightning current flows in the steel conduit than in the copper down conductor because of the skin effect and choking effect. Therefore to reduce the adverse effects such as the electrostatic induction and side flashes caused by the potential rise of down conductors due to lightning currents, it is extremely effective to bond the down conductor to the steel conduit and steel frame of structures.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.8
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• pp.678-687
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• 2012

The Fly-By-Wire(FBW) flight control system is essential to improve the stability and flying quality of the helicopter. Advanced aerospace companies, such as Bell-Sikorsky (USA) and NHI (European Consortium), have already applied the FBW flight control system to manufacture V-22 and NH-90 helicopters, respectively. This paper addresses the development of control law design using model inversion method improve the hover and low speed handling qualities of helicopter based on BO-105 model in 'Day' and 'Degraded visual environments(DVEs)' in accordance with ADS-33E-PRF. Design parameters are optimized to satisfy the handling qualities specification using Control Designer's Unified Interface (CONDUIT) commercial control law software. The result of the analysis based on CONDUIT and non-real time simulation in-house software, HETLAS (HElicopter Trim Linearization And Simulation) reveals that the provides an efficient mean to achieve Level 1 handling qualities.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.37-40
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• 1996

Cable-In-Conduit Conductor(CICC) is widely accepted as an advanced superconductor configuration for large scale applications such as tokamak fusion reactors, MAGLEV (MAGnetic LEVitation), and SMES (Superconducting Magnetic Energy Storage). The stability of CICC cooled with supercritical helium can be very high if it is operated below a certain limiting current. This limiting current can be determined by Stekly type heat balance equation. The stability characteristic of CICC for AC operation is more complicated than that of DC because there are additional instability sources which are associated with local flux change. Ramp-rate limitation is a phenomenon discovered during US-DPC (United States-Demonstration Poloidal Coil) program, which showed apparent quench current degradation associated with high dB/dt. This paper describes recent experimental investigation results on the ramp-rate limitation and discusses current imbalance, induced current, current redistribution due to local quench of the strand in the cable.