• Transactions of Materials Processing
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• v.33 no.3
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• pp.169-177
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• 2024

Recently, hydrogen energy has been widely used because of strict regulations on greenhouse gas emissions. For using the hydrogen energy, it is required to supply hydrogen through a tube trailer. However hydrogen tube trailer can have excessive load problems during transportation due to reasons such as road shape and driving method, which may lead a risk of hydrogen leakage. So it is necessary to secure a high level of safety. The purpose of this study is to evaluate structural safety for the conservative design of hydrogen tube trailer. First, finite element(FE) modeling of the designed hydrogen tube trailer was performed. After that, safety evaluation method was established through static structural simulation based on the standard GC207 conditions. In addition, effectiveness of the designed model was confirmed through the results of the structural safety evaluation. Finally, driving simulation was used to derive acceleration graph according to time, which was considered as a dynamic property for the evaluation of conservative tube trailer safety evaluation. And dynamic structural simulation was conducted as a condition for actual transportation of tube trailer by applying dynamic properties. As a results, conservative safety was evaluated through dynamic structural simulation and the safety of hydrogen tube trailer was confirmed through satisfaction of the safety rate.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1982.05a
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• pp.14.2-15
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• 1982

Serous otitis media (SOM) is one of the most common otologic diseases which was first discribed by Politzer in 1869. Currentely, among many methods introduced to treat SOM, ventilation tube insertion is considered to be the most popular and standard method being used. However due to complication of it, there remains many disputable various problems. In order to review the clinical aspect of SOM and search for the effects and safety of ventilation tube, we studied 97 SOM patients, who had performed V-tube from Jan. 1981 to Feb. 1982 at ENT dept. of Severance Hospital. Analizing the clinical symptoms, age distribution, associated disease, otoscopic findings of ear drum, degree of hearing loss, hearing gain after insertion of V-tube and complications, following results were obtained. 1) As a subjective symptom, among 29 cases all patients had hearing loss, 19 cases (65.6%) had tinnitus, 12 cases (44.4%) had autophony and 10 cases (34.5%) of the patients had sensation of ear fullness. 2) In age distribution, 6 to 10 year old group was most numerous up to 42 cases (43.3%) and 20 years and over was 23 cases (23.5%) 3) In adult group SOM tend to be involved unilaterally whereas young child group had tendency involving bilaterally. 4) 49 cases (50.05%) were associated with tonsillitis and adenoid vegetation, 15 cases (15.5%) were associated with sinusitis, 4 cases (4.1%) had nasal allergy. 5) In preoperative otoscopic findings, 62 ears (47.7%) had retraction, 37 ears (23.6%) had bulging, 34 ears (21.7%) had color change, and 29 ears (19.7%) had no significant findings. 6) In characteristics of middle ear fluid, child group was tend to have mucinous content (84.2%) while adult group had serous content (62.5%). 7) Average preoperative air-bone gap of pure tone was 25.3 dB. 8) 24 ears (72.7%) had over 10 dB of postoperative hearing gain and average hearing gain was 17.2 dB. 9) There were 44 ears (28.1%) of complications. Among them 37 ears (23.6%) had infection, 3 ears had atelectasis, 2 ears had granulation tissue, 2 ears had permanent perforations. 10) Among 37 ears suffered from post-op. infection, 19 ears (51.4%) had initial infection just after insertion of ventilation tube, 18 ears (48.6%) were infected during the course of post-ventilation tube. Of 37 infected ears, 26 ears (70.3%) responded to conservative care, while 11 ears (29.7%) was cured after removal of ventilation tube.

• Advances in pediatric surgery
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• v.10 no.2
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• pp.92-98
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• 2004

The history of esophageal replacement in infants or children is the history of development of various kinds of alternative conduits such as stomach, colon, and small bowel. The gastric tube has been the most widely used conduit. From January 1988 to May 2003, 23 esophageal replacements with gastric tube were performed at the Department of Pediatric Surgery, Seoul National University Childrens Hospital. Statistical analysis was performed using Windows SPSS11.0 Pearson exact test. There were Gross type A(n=10), type B(n=1), type C(n=11), type D(n=1). Ten patients who had long gap esophageal atresia (type A-8, type B-1, type C-1) and 13 patients (type A 2, type C-10, type D-1) who had stenosis, leakage, recurred tracheoesophageal fistula, and esophagocutaneous fistula after previous corrective operations, had esophageal replacement with gastric tube. Mean follow-up periods were 4 year 2 months (7 months-15 year 1 month). There were postoperative complications including GERD in 16 (69.6 %), leakages in 7 (30.4 %), diverticulum at anastomosis in 2 (8.7 %), anastomosis site stenosis in 4 (17.3 %), and distal stenosis of the gastric tube in 1 (4.3 %). There was no statistical significance between operation types and postoperative leakage and gastroesophageal reflux. In conclusion, esophageal replacement with gastric tube may be a useful surgical option in esophageal atresia with long gap and esophageal atresia complicated by previous corrective operation.

• Transactions of Materials Processing
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• v.13 no.8
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• pp.663-670
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• 2004

The bending phenomenon has been known to be occurred by the difference of velocity at the die exit. The difference of velocity at the die exit section can be obtained by the different velocity of billets through the multi-hole container. The difference of velocity at the die exit can be controlled by the two variables, the one of them is the different velocity of extrusion punch through the multi-hole container, the other is the difference of hole diameter of muliti-hole container. In this paper the difference of hole diameter is applied. So it can bend during extruding products because of the different amount of two billets when billets would be bonded in the porthole dies cavity. And the bending curvature can be controlled by the size of holes. The experiments with aluminum material for the curved tube product had been done for circular or rectangular curved tube section. The results of the experiments show that the curved tube product can be formed by the extru-bending process without the defects such as distortion of section and thickness change of wall of tube and folding and wrinkling. The curvature of product can be controlled by shape of cross section and the difference of billet diameters. And it is known that the bonding and extruding and bending process can be done simultaneously in the die cavity by the experiments that rectangular hollow curved tubes could be extruded by porthole dies with four different size billets made of aluminum material. And it shows that bending phenomenon can happen during extruding with for different billets from the analysis by DEFORM-3D.

• Magazine of the Korea Concrete Institute
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• v.7 no.5
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• pp.133-144
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• 1995

This study investigated to the properties of structural behaviors through a series of experiment with the key parameter, such as diameter-to-thickness(D/t) ratio, selenderness ratio of steel t~ube and strength of concrete under loading condition simple confined concrete by steel tube as a fundmental study on adaptability with structural members in high-rise building. The obtained results are sumnarised as follow. (1) The fracture mode of confined concrete was presented digonal tension fracture in the direction of $45^{\circ}$ with compression failure at the end of specimen in stub column, but the fracture mode of long column was assumed an aspect of bending fracture transversely. (2) The deformation capacity and ductility effect was increased by confine steel tube for concrete. (3) 'The emprical formula to predict the ultimate capacity of confined concrete by steel tube and concrete filled steel tube column using restraint of concrete considered D / t ratio, selenderness ratio of steel tube anti strength of' concrete were proposed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.943-944
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• 2013

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.5 no.1 s.9
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• pp.13-19
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• 2006

In this paper, a broadband Microwave Power Module(MPM) operating at 7 - 11 GHz is designed and fabricated. The MPM consists of a SSA (Solid State Amplifier) and a conventional TWT (traveling Wave Tube). This combined module takes advantage of a low noise and high gain of SSA. The computer modeling and simulation of the SSA are designed by the use of the ADS (Advanced Design System) software. The SSA is designed by configurating the CSSDA (Cascaded Single Stage Distributed Amplifier). The broadband MPM is measured to be noise figure 8.3 - 10.02 dB at 7 - 11 GHz bandwidth, output power of 38.12 dBm at 9 GHz.

• Korean Journal of Plant Taxonomy
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• v.43 no.2
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• pp.94-98
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• 2013

A new species, Daphne jejudoensis M. Kim, has been named and described from Seonheul, Jejudo Province, Korea. Daphne jejudoensis shares several characteristics (white calyx colors, long calyx tube, evergreen leaves, leathery leaf textures, etc.) with its related species D. kiusiana, but it is distinct from D. kiusiana which has a hairy calyx tube and lobes, short calyx lobes, oblanceolate leaves (with acute apex), and a different distribution (coastal region in Geojedo Is.) by having a glabrous calyx tube and lobes, long calyx lobes, elliptic leaves (with acuminate apex), and by its distribution (inland region in Jejudo Is.).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.10
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• pp.938-946
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• 2005

Shape optimization of internally finned circular tube has been peformed for periodically fully developed turbulent flow and heat transfer. The physical domain considered in this study is very complicated due to periodic boundary conditions both streamwise and circumferential directions. Therefore, Pareto frontier sets of a heat exchanger can be acquired by coupling the CFD and the multi-objective genetic algorithm, which is a global optimization technique. The optimal values of fin widths $(d_1,\;d_2)$ and fin height (H) are numerically obtained by minimizing the pressure loss and maximizing the heat transfer rate within ranges of $d_1=0.2\sim1.5\;mm,\;d_2=0.2\sun1.5\;mm,\;and\;H=0.2\sim1.5\;mm$. The optimal values of the design variables are acquired after the fifth generation and also compared to those of a local optimization algorithm for the same geometry and conditions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.196-199
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• 2011

Subscale high-pressure injection system which use two-stage light gas gun composed with high-pressure tube, pump tube and launch tube can make supersonic liquid jet. The supersonic liquid jet enhances droplet atomization by shockwave in front of the jet. In this study, the experiments was executed to identify the atomization characteristics of the supersonic liquid jet using straight cone nozzle. SMD which presents the atomization characteristics was decreased from $151.2{\mu}m$ to $52.25{\mu}m$ by increasing of L/d.