• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.531-536
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• 1999

Experiments on micro-leak of water were carried out with the water injecting simulator in liquid sodium atmosphere. The leak path was plugged by the sodium-water reaction products in the 2.25Cr-1Mo steel specimen. However, leak paths re-opened in most cases. The self-wastage patterns were not affected by the sodium temperature in the re-opened specimen. The diameter of the defected area, including the re-opened part, was about 5 min. It took 143, 40.7 and 34.7 minutes to re-open the leak path at 450, 475, and $510^{\circ}C$, respectively. It was concluded that the reopening time decreased with the increasing temperature.

• Tunnel and Underground Space
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• v.6 no.3
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• pp.209-222
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• 1996

Shut-in pressure, reopenting pressure and fracture orientation are very important parameters to be evaluated precisely in in-situ stress measurement by hydraulic fracturing. Graphical methods on pressure-time curves have been conventionally used, even though these are seriously dependent on subjectivity of interpreters. So there have been many demands on new method to objectivity in determining parameters. We have developed integrated hydrofracturing data processing program (HYDFRAC), based on nonlinear regression analysis and can be invoked under the Window graphical user interface. HYDFRAC consiste of three routines, that is shut-in pressure routine, reopening pressure routine, and fracture delineation routine. Each of routines include independent modules according to parameter determination methods. Its application to field tests ensured both objectivity and facility in determining of hydraulic fracturing parameters. Determining shut-in pressures at each pressurization cycles, we adopted the exponential pressure-decay method(EPD method), the bilinear pressure-decay-rate method (PDR method), and the tangent intersection method in order to find the pressurization-cyclic tendency of shut-in pressures. The estimated pressure by PDR method exists in the range of the upper and lower values by EPD method, and lies near to the upper value more than the lower. Being the pressurization cycle increased, the range of upper and lower limits come to be stabilized gradually. By graphical superposition method and bilinear pressure-accumulated volume method, reopening pressures were determined. Vertical and inclined fracture attitudes were determined by applying the directional statistics and sinusoidal curve fitting, respectively. The results of evaluation of hydrofracturing parameters showed that statistical methods could enhance the objectivity better than graphical methods.

• Journal of Chest Surgery
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• v.28 no.11
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• pp.977-982
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• 1995

Early repair of complex congenital heart malformation may lead to life-threatening respiratory and hemodynamic embarrassment on sternal closure. We performed delayed sternal closure in nine neonates to avoid a fatal outcome in these situations. Primary elective open sternum was used in 8 [66.7% and primary sternal closure in 4 [33.3% of the 12 patients studied. one patient with primary sternal closure underwent delayed sternal reopening in the intensive care unit. Of the 9 patients with open sternum, 2 patients died of low cardiac output and acute renal failure respectively before delayed sternal closure. 7 patients could undergo delayed sternal closures 3 days after initial operation. The mean age at open cardiac procedure was 14.3 days [range 3 to 30 and mean preoperative weight was 3.4kg [range 2.8 to 4.1 . The aortic cross-clamping time was longer in the group with open sternum than the group with closed sternum [p=0.042 . There was no morbidity and mortality related to delayed sternal closure. Given the low morbidity and potential benifits, this technique should be used in neonates after open heart procedures when postoperative mediastinal compression produces frank low cardiac output or respiratoy compromise during a trial of sternal closure.

• Journal of Korean Neurosurgical Society
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• v.51 no.2
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• pp.75-80
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• 2012

Objective : To optimize the recanalization of acute cerebral stroke that were not effectively resolved by conventional intraarterial thrombolysis (IAT), we designed a double device technique to allow for rapid and effective reopening. In this article, we describe the feasibility and efficacy of this technique. Methods : From January 2008 to September 2009, twenty patients with acute cerebral arterial occlusion (middle cerebral artery : n=12; internal carotid artery terminus : n=5; basilar artery : n=3) were treated by the double device technique. This technique was applied when conventional thrombolytic methods using drug, microwires, microcatheters and balloons did not result in recanalization. In the double device technique, two devices are simultaneously placed at the lesion (for example, one microcatheter and one balloon or two microcatheters). Chemicomechanical or mechanicomechanical thrombolysis was performed simultaneously using various combinations of two devices. Recanalization rates, procedural time, complications, and clinical outcomes were analyzed. Results : The initial median National Institute of Health Stroke Scale (NIHSS) was 16 (range 5-26). The double device technique was applied after conventional IAT methods failed. Recanalization was achieved in 18 patients (90%). Among them, 55% (11 cases) were complete (thrombolysis in cerebral infarction 2B, 3). The median thrombolytic procedural time including the conventional technique was $135{\pm}83.7$ minutes (range 75-427). Major symptomatic hemorrhages (neurological deterioration ${\geq}4$ points in NIHSS) developed in two patients (10%). Good long term outcomes (modified Rankin Scale ${\leq}2$ at 90 days) occurred in 25% (n=5) of the cases. Mortality within 90 days developed in two cases (10%). Conclusion : The double device technique is a feasible and effective technical option for large vessel occlusion refractory to conventional thrombolysis.

• The Journal of the Petrological Society of Korea
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• v.26 no.4
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• pp.341-352
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• 2017

The Jipum Volcanics, occurred in western Yeongdeok, are a stratigraphic unit that is composed of rhyolitic pyroclastic rocks, tuffites, andesitic hyaloclastites, rhyolite lavas, tuffaceous conglomerates and andesite lavas. The SHRIMP U-Pb zircon dating yielded eruption ages of $68.5{\pm}1.6Ma$ from the rhyolitic pyroclastic rocks. Around the time, the unit was generated by dominant rhyolitic volcanisms and locally added by concomitant andesitc volcanisms from another vents. The rhyolitic volcanisms first produced the pyroclastic rocks by phreatomagmatic explosions from rhyolitic magma, later made of the rhyolite lava dome by lava effusions from reopening of the rhyolitc magma at the existing vent. At the time between first and second rhyolitic volcanisms, the tuffites were deposited at a shallow depression in the distal volcanic edifice, and andesitic volcanisms first made of the hyaloclastites by quench fragmentation when hot andesite lavas flew into the depression to contact with cold water. and the Jipum volcano was finally covered with the thin andesitic lavas by lava effusions from another vent.

• Cartoon and Animation Studies
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• s.17
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• pp.175-186
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• 2009

With its reopening in 2009, Korea Manhwa Contents Agency(KOMACON) divided its major business into two domains named "Contents Business Center" and "Museum Manhwa Gyujanggak", in charge of promoting Korean manhwa industry and Korean manhwa culture, respectively, in two separate buildings. Since the former is not likely to earn operation income for the time being at least because of the nature of the business, the latter plays an all the more important role. Accordingly, it is requisite for KOMACON to develop an operating plan for the museum which can be regarded as a multi-cultural space of manhwa in that it includes various cultural activities including exhibition, library, and research. This paper aims to propose a basic framework for its purpose of foundation, objects, organization, and personnel composition, and then, its sources of operating income-business operating profit and financing-, if not all of the details regarding the museum.

• Advances in biomechanics and applications
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• v.1 no.2
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• pp.127-141
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• 2014

A preliminary study of a new pulsatile pump that will work to a frequency greater than 1 Hz, is presented. The fluid-structure interaction between a Newtonian blood flow and a piston drive that moves with periodic speed is simulated. The mechanism is of double effect and has four valves, two at the input flow and two at the output flow; the valves are simulated with specified velocity of closing and reopening. The simulation is made with finite elements software named COMSOL Multiphysics 3.3 to resolve the flow in a preliminary planar configuration. The geometry is 2D to determine areas of high speeds and high shear stresses that can cause hemolysis and platelet aggregation. The opening and closing valves are modelled by solid structure interacting with flow, the rhythmic opening and closing are synchronized with the piston harmonic movement. The boundary conditions at the input and output areas are only normal traction with reference pressure. On the other hand, the fluid structure interactions are manifested due to the non-slip boundary conditions over the piston moving surfaces, moving valve contours and fix pump walls. The non-physiologic frequency pulsatile pump, from the viewpoint of fluid flow analysis, is predicted feasible and with characteristic of low hemolysis and low thrombogenesis, because the stress tension and resident time are smaller than the limit and the vortices are destroyed for the periodic flow.

• Advances in pediatric surgery
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• v.17 no.2
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• pp.133-138
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• 2011

Extracorporeal membrane oxygenation (ECMO) has been utilized in congenital diaphragmatic hernia (CDH) patients with severe respiratory failure unresponsive to conventional medical treatment. We retrospectively reviewed 12 CDH patients who were treated using ECMO in our center between April 2008 and February 2011. The pre ECMO and on ECMO variables analyzed included gestational age, sex, birth weight, age at the time of ECMO cannulation, arterial blood gas analysis results, CDH location, timing of CDH repair operation, complications and survival. There were 9 boys and 3 girls. All patients were prenatally diagnosed. Mean gestational age was $38.8{\pm}1.7$ weeks and mean birth weight was $3031{\pm}499$ gram. Mean age at the time of ECMO cannulation was $29.9{\pm}28.9$ hours. There were 4 patients who survived. Survivors showed higher 5 min Apgar scores ($8.25{\pm}0.96$ vs. $7.00{\pm}1.20$, p=0.109), higher pre ECMO mean pH ($7.258 {\pm}0.830$ vs. $7.159{\pm}0.986$, p=0.073) and lower pre ECMO $PaCO_2$ ($48.2{\pm}7.9$ vs. $64.8{\pm}16.1$, p=0.109) without statistical significance. The hernia was located on the left side in 10 patients and the right side in 2 patients. The time interval from ECMO placement to operative repair was about 3~4 days in 5 early cases and around 24 in the remaining cases. There were 3 cases of post operative bleeding requiring re operation and 2 cases of abdominal compartment syndrome requiring abdominal fascia reopening. ECMO catheter reposition was required in 4 cases. Three cases of arterial or venous thrombosis were detected and improved with follow up. Our data suggests that ECMO therapy could save the lives of some neonates with CDH who can not be maintained on other treatment modalities. Protocolized management and accumulation of case experience might be valuable in improving outcomes for neonates with CDH treated with ECMO.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.103-110
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• 2019

Damage to the pavement system due to various causes will be required rapid repair work for reopening the vehicle traffic. The magnesium oxide phosphate composite(MPC) has a short curing time and is capable of early compressive strength development, is suitable for rapid repair materials. The aim of this study was to evaluate the hardening and compressive strength characteristics of MPC according to the water-binder (W / B) ratio and magnesium-phosphate(M / P) ratio in order to develop repair materials consisted with light burned magnesia and potassium dihydrogen phosphate. In order to ensure the workability in the field application, the difference of mechanical properties according to standard sand and ordinary sand and performance of retards were evaluated. The mix proportion with W/B ratio was about 35% and the M/P ratio was about 1.0 ~ 1.2 has a superior perfomance with strength and hardening condition. Especially, the strength of composite at only 1 day curing with W/B ratio of 0.35 and the M/P ratio of 1.2 was shown the higher than 25.0 MPa. Boric acid as a retarder was found to be suitable for ensuring the working time, and the purity of magnesium oxide was about 90 ~ 95%, which is effective for ensuring curing time and strength.