• Nuclear Engineering and Technology
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• v.50 no.3
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• pp.356-367
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• 2018

A series of tests dedicated to station blackout (SBO) accident scenarios have been recently performed at the $Prim{\ddot{a}}rkreislauf-Versuchsanlage$ (primary coolant loop test facility; PKL) facility in the framework of the OECD/NEA PKL-3 project. These investigations address current safety issues related to beyond design basis accident transients with significant core heat up. This work presents a detailed analysis using the best estimate thermal-hydraulic code TRACE (v5.0 Patch4) of different SBO scenarios conducted at the PKL facility; failures of high- and low-pressure safety injection systems together with steam generator (SG) feedwater supply are considered, thus calling for adequate accident management actions and timely implementation of alternative emergency cooling procedures to prevent core meltdown. The presented analysis evaluates the capability of the applied TRACE model of the PKL facility to correctly capture the sequences of events in the different SBO scenarios, namely the SBO tests H2.1, H2.2 run 1 and H2.2 run 2, including symmetric or asymmetric secondary side depressurization, primary side depressurization, accumulator (ACC) injection in the cold legs and secondary side feeding with mobile pump and/or primary side emergency core coolant injection from the fuel pool cooling pump. This study is focused specifically on the prediction of the core exit temperature, which drives the execution of the most relevant accident management actions. This work presents, in particular, the key improvements made to the TRACE model that helped to improve the code predictions, including the modeling of dynamical heat losses, the nodalization of SGs' heat exchanger tubes and the ACCs. Another relevant aspect of this work is to evaluate how well the model simulations of the three different scenarios qualitatively and quantitatively capture the trends and results exhibited by the actual experiments. For instance, how the number of SGs considered for secondary side depressurization affects the heat transfer from primary side; how the discharge capacity of the pressurizer relief valve affects the dynamics of the transient; how ACC initial pressure and nitrogen release affect the grace time between ACC injection and subsequent core heat up; and how well the alternative feeding modes of the secondary and/or primary side with mobile injection pumps affect core quenching and ensure stable long-term core cooling under controlled boiling conditions.

• Journal of Chest Surgery
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• v.35 no.4
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• pp.290-295
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• 2002

Backgroud: Pneumonectomy carries the possibility of numerous dangerous complications as well as the vast effect the operation itself has on the cardiopulmonary function. Most of operations are done with the insertion of the chest tubes upon completion, but because of the high incidence of pyothorax as its complications, we have tried to analyze and compare the cases without inserting the chest tubes. Material and Method: During a 5 year period from January, 1996 to December 2000, 100 cases, which were operated at the Hanyang University Hospital, were selected using the patient's charts. The age, gender, indication of operation, associated diseases, and operation site(left or right) were classified accordingly and the postoperative complications and mortality were statistically analyzed using the $\chi$ 2-test. After resecting the lung, the intrathoracic pressure was set at -15 ~ -20cm $H_2O$ using the nelaton catheter, and the thoracotomy site was then closed. The gradual collection of the fluid and blood in the thorax of the operated side, as well as the mediastinum location, were observed carefully for 4~5 days postoperatively with the aid of the simple chest x-rays. Result: Of the 100 cases, 16 cases of pulmonary tuberculosis(16%), 81 cases of lung tumor(81%), 2 cases of bronchiectasis(2%), and 1 case of aspergilloma associated bronchiectasis were noted. There were 8 mortality cases(8%), and of the 34 cases(34%), 44 complications were noted. The age, sex, and operation site(left or right) were not statistically significant with the complications. 7 of the 16 cases of pulmonary tuberculosis(44%) and 27 of the 81 cases of lung tumor(33%) had complications, but they were found not to be statistically significant. The increase of the complication rate in the pulmonary tuberculosis patients was 3.86. The evidence of postoperative bleeding was observed in 6 cases with the 3 cases being the pulmonary tuberculosis patients and the 3 cases were others. This shows that the increase in postoperative bleeding in the pulmonary tuberculosis is statistically significant(p=0.019). Of the 100 cases, there were 8 mortality cases(8%), with 5 cases from the 81 cases of the lung tumor group(6.1%), 3 cases from the 16 cases of pulmonary tuberculoses group(18.7%).

• Clinical and Experimental Pediatrics
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• v.49 no.11
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• pp.1194-1201
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• 2006

Purpose : The comatose mentality can be catastrophic, especially if the condition is severe or the duration is prolonged. Therefore, delayed diagnosis can result in a poor outcome or death. The best radiologic modality to differentiate from cerebral lesions in patients suffering from cerebral diseases is magnetic resonance imaging (MRI) rather than computed tomography (CT). Special apparatuses with metal materials such as ventilators, and cardiac pacemakers belonging to patients cannot be located in the magnetic field. We aimed to exhibit the possibility of examining MRI, maintaining ventilation at a relative long distance by means of modified $Ambu^{(R)}$. Methods : Self-inflating bags as a sort of a manual ventilator, connected with relatively long extension tubes instead of mechanical ventilators, were adopted to obtain MRI. PVC (polyvinyl chloride) extension tubes had different lengths and diameters. Lengths were 1, 2, and 3 cm and diameters were 15, and 25 mm. The work of breathing and expiratory changes of expiratory tidal volume (TVe), minute volume of expiration (MVe), peak inspiratory pressure (PIP) were measured by use of the mechanical ventilator, $Servoi^{(R)}$, as the alteration of TVi (inspiratory tidal volume), extension tube lengths and diameters with other values fixed. Results : Measured TVe and MVe by ventilator were the same values with control at every TVi, regardless of extension tube lengths and diameters, but PIP were increased with the rise of TVi, tube lengths, with decline of tube diameters, these were statistically significant. Conclusion : MRI examination can be carried out with a self-inflating bag connected with an extension tube at a long distance in patients who need artificial ventilation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.4
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• pp.423-434
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• 1995

It was used boundary element method(BEM) and analysed axisymmetric problem to solve hydraulic cylinder for large vessel acting uniform internal pressure(25N/m super(2)) within elastic limit. This paper was utilized the carbon steel tubes for machine structural purposed model, inner radius was 150mm and outer radius was 250mm, axial length was semi-infinite and the isoparametric element was used. The important results obtained in this study were summarized as follows. Radial, tangential and shearing stress occured the maximum stresses(48, -20 and 34MPa) at the inner radius and the minimum stresses(32, -4 and 18MPa) at the outer radius of the hydraulic cylinder for large vessel. But negative signs have meaning compressive stress and stress diminution ratio was about 0.15MPa/mm. The use of isoparametric element raised accuracy and the increment of input data lessened the error in internal point but computer run-time was increased. The double node was improved the internal solutions to settle discontinuity at corner and the double exponential formula lessened error of stress value at boundary neighborhood. And then coincidence between the analytical and exact results is found to be fairly good, showing that the proposed analytical by BEM is reliable.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4721-4726
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• 2010

The performance characteristics of water-chilling heat pump using CO2 for the control of inverter frequency was investigated experimentally. An experimental apparatus is consisted of a compressor, a gas cooler, an expansion valve, an evaporator and a liquid receiver. All heat exchangers used in the test rig are counter flow type heat exchangers with concentric dual tubes, which are made of copper. The gas cooler and the evaporator consist of 6 and 4 straight sections respectively arranged in parallel, each has 2.4m length. The experimental results summarize as the following: for constant inlet temperature of evaporator and gas cooler, as mass flow rate, compression ratio and discharge pressure increases with the inverter frequency. And heating capacity and compressor work increases, but coefficient of performance(COP) decreases with the inverter frequency of compressor. As inlet temperature of secondary fluid in the evaporator increases from $15^{\circ}C$ to $25^{\circ}C$, compression ratio and compressor work decreases, but mass flow rate, heating capacity and COP increases with the inverter frequency of compressor. The above tendency is similar with performance variation with respect to the variation of inverter frequency in the conventional vapor compression refrigeration cycle.

• Archives of Plastic Surgery
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• v.36 no.3
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• pp.351-355
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• 2009

Purpose: Cervical necrotizing fasciitis tends to involve the deep soft tissues and spread caudally to the anterior chest and mediastinum, often resulting in major complications and death. It may rapidly spread into the thorax along fascial planes, and the associated diagnostic delay results in this descending necrotizing mediastinitis. So, aggressive multidisciplinary therapy with surgical drainage is mandatory. We present a very rare case of descending necrotizing mediastinitis with literature review. Methods: A 53 years old male visited our department 7 days after trauma in neck. His premorbid conditions and risk factors of necrotizing fasciitis were concealed hepatoma, trauma history, chronic liver disease, and nutrition deficit. Computed tomographic scans of the head and neck region were performed in this patient : signs of necrotizing fasciitis, were seen in the platysma, sternocleidomastoid, trapezius muscle and strap muscles of the neck. Fluid accumulations involved multiple neck spaces and mediastinum. At the time, he diagnosed as necrotizing fasciitis on his neck and anterior chest. Necrotic wound was excised serially and we treated this with the Vacuum - assisted closure(VAC, Kinetics Concepts International, San Antonio, Texas) system device. After appropriately shaping the sponge and achieving additional 3 pieces drainage tubes in the pockets, continuous negative pressure of 125 mmHg was applied. The VAC therapy was utilized for a period of 12 days. Results: We obtained satisfactory results from wide excision, abscess drainage with the VAC system, and then split thickness skin graft. The postoperative course was uneventful. Conclusion: The refined technique using the VAC system can provide a means of simple and effective management for the descending necrotizing mediastinitis, with better cosmetic and functional results. Finally, the VAC system has been adopted as the standard treatment for deep cervical and mediastinal wound infections as a result of the excellent clinical outcome.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.11
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• pp.1027-1033
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• 2010

A two-phase (gas-liquid) flow is a common phenomenon in fluidic systems, e.g., fluidic systems in the electro-magnetic or nuclear power generation industry and in the steel industry. The measurement of a two-phase flow is important for guaranteeing the safety of the system and for achieving the desired performance. The measurement of the void fraction, which is one of the parameters of the two-phase flow that determines the pressure drop and heat transfer coefficient, is very important. The time resolution achieved by employing the impedance method that can be used to calculate the void fraction from the impedance of the fluid is high because the electric characteristics are taken into account. Therefore, this method can be employed to accurately measure the void fraction without distortion of flow in real time by placing electrodes on the walls of the tubes. Coney analytically studied a ring-type impedance meter, which can be employed in a circular tube. The aim of this study is to experimentally verify the robustness of a three-ring impedance meter to variations in the electric conductivity of the fluid; this robustness was suggested by Coney but was not experimentally verified.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.5
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• pp.407-415
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• 2008

The tubes in heat exchanger are typically made from copper alloy, stainless steel, carbon steel, titanium alloy material. type-439 ferritic stainless steel is ferromagnetic material, and furnish higher heat transfer rates than austenitic stainless steels and higher resistance to corrosion-induced flaws. Ferritic stainless steel can typically be found in low-pressure(LP) feedwater heaters and moisture separator reheaters(MSRs). LP feedwater heaters generally utilize thin wall type-439 stainless steel tubing, whereas MSRs typically employ a heavier wall tubing with integral fins. Service-induced damage can occur on the OD(outside diameter) surface of type-439 ferritic stainless steel tubing which is employed for MSRs tubing, and the most typical damage mechanism is vibration-induced tube-to-TSP(tube support plate) wear and fatigue cracking. The wear has been reported that occurs mainly on the OD surface. Accordingly, in this study, we have evaluated the flaw sizing capability of magnetic saturation eddy current technique using magnetic saturation probe and flawed specimen.

• Journal of Radiation Protection and Research
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• v.31 no.1
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• pp.37-46
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• 2006

For the first step to develop a reference disposal container of spent fuel to be used in a deep geological repository, this paper examined safe dimensions of the disposal container on the points of nuclear criticality and radiation safety and mechanical structural safety and provided basic information for dimensioning the container and configuration of the container components, and establishing the favorable and safe disposal conditions. When the safety factor for stress due to the external loads (hydrostatic and swelling pressure) is taken as 2.0, the safe diameter of the filler material to provide enough container strength under the assumed external loads is found to be 112cm with 13cm spacing between inner baskets in PWR container. Also the thickness of the thinner section between the fuel basket and the surface of the cast insert is determined to be 150 mm. Regarding these dimensions of the container, the PWR fuel container is sketched to accommodate 4 square assemblies or 297 CANDU fuel 297 bundles (33 circle tubes x 9 stacks). However the top and bottom parts need to be checked again through the detail radiation shielding analysis with respects to the emplacement position and handling processes of the disposal container.

• Journal of Veterinary Clinics
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• v.29 no.5
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• pp.368-371
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• 2012

The present study evaluated the outcome of use of thoracostomy tube tunneling technique under the latissimus dorsi muscle for the evacuation of postoperative pneumothorax induced by thoracotomy in 11 dogs. A stab incision was made through the skin and the latissimus dorsi muscle over the rib in the fifth intercostal space caudal to a surgical window. The thoracostomy tube with a Kelly hemostat was advanced into the thoracic cavity in a cranioventral direction through the sublatissimal tunnel. After tube placement, a # 1 nylon horizontal mattress suture was placed around the skin incision. The thoracostomy tube was removed after creating a negative pressure in the thoracic cavity. Dogs were monitored after surgery for pneumothorax, subcutaneous emphysema, clinical signs including dyspnea, and tube kinking in a muscle tunnel using physical examination and postoperative radiography. There was no tube kinking in the sublatissimal tunnel in 11 dogs on introducing the tubes into the thoracic cavity. The mean (${\pm}SD$) follow-up period was $19{\pm}10$ months. On postoperative radiography, there was no evidence of pneumothorax in 11 dogs. Subcutaneous emphysema was identified around the stab incision in a dog postoperatively. The subcutaneous emphysema disappeared spontaneously within 3 days. On postoperative physical examination, there was no evidence of dyspnea in 11 dogs. Our results suggest that the sublatissimal tunneling technique for thoracostomy tube placement is effective to prevent air leakage around the thoracostomy tube while the tube remains in the thoracic cavity and along the thoracostomy tunnel after tube removal. Tunneling under the latissimus dorsi muscle should be considered the thoracostomy tube placement technique to prevent iatrogenic pneumothorax with first priority.