• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.402-409
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• 2019

When a loss of coolant accident (LOCA) occurs in a nuclear power plant, accident scenarios which can prevent core damage are defined based on break size. Current probabilistic safety assessment evaluates that core damage can be prevented under small-break LOCA (SBLOCA) and steam generator tube rupture (SGTR) with rapid cool down (RCD) strategy when all safety injection systems are unavailable. However, previous research has pointed out a limitation of RCD in terms of initiation time. Therefore, RCD success criteria estimation based on allowable coping time under a SBLOCA or SGTR when all safety injection systems are unavailable was performed based on time-line and thermal-hydraulic analyses. The time line analysis assumed a single emergency operating procedure flow, and the thermal hydraulic analysis utilized MARS-KS code with variables of break size, cooling rate, and operator allowable time. Results show while RCD is possible under SGTR, it is impossible under SBLOCA at the APR1400's current cooling rate limitation of 55 K/hr. A success criteria map for RCD under SBLOCA is suggested without cooling rate limitation.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.1
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• pp.51-58
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• 2021

Chemical decontamination of primary systems in a nuclear power plant (NPP) prior to commencing the main decommissioning activities is required to reduce radiation exposure during its process. The entire process is repeated until the desired decontamination factor is obtained. To achieve improved decontamination factors over a shorter time with fewer cycles, the appropriate flow characteristics are required. In addition, to prepare an operating procedure that is adaptable to various conditions and situations, the transient analysis results would be required for operator action and system impact assessment. In this study, the flow characteristics in the steady-state and transient conditions for the chemical decontamination operations of the Kori-1 NPP were analyzed and compared via the MARS-KS code simulation. Loss of residual heat removal (RHR) and steam generator tube rupture (SGTR) simulations were conducted for the postulated abnormal events. Loss of RHR results showed the reactor coolant system (RCS) temperature increase, which can damage the reactor coolant pump (RCP)s by its cavitation. The SGTR results indicated a void formation in the RCS interior by the decrease in pressurizer (PZR) pressure, which can cause surface exposure and tripping of the RCPs unless proper actions are taken before the required pressure limit is achieved.

• Medical Lasers
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• v.9 no.1
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• pp.65-70
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• 2020

Bronchial foreign body aspiration (BFA) is a common but emergent condition in infants and children. Furthermore, it can result in various complications such as atelectasis, pneumonia, bronchiectasis, and pneumothorax. Among these, pneumothorax is a very rare complication. However, it can be fatal without the swift implementation of appropriate treatment. We experienced a case of 16-month-old girl with an aspirated peanut. The foreign body was fixed in her left main bronchus. A CO₂ laser was used to safely cut and break the foreign body. Removal was successful after breaking it. But after the process, inflammatory tissue of the tracheal mucosa was ruptured. Bilateral tension pneumothorax followed after the rupture. The patient was treated with bilateral chest tube insertion. Here we present this BFA case with a rare and unexpected complication. We also review the appropriate literature.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.26 no.5
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• pp.284-289
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• 2023

A 14-year-old girl was admitted to the emergency department for excessive bile-containing vomiting and severe abdominal pain. She had been healthy until she intentionally lost 25 kg over a 6-month period. Thick, bloody bile-mixed food particles were drained from the stomach through a nasogastric tube. Abdominal computed tomography revealed huge stomach dilatation with extensive gastric pneumatosis, possible near rupture, acute pancreatitis, and a very narrow third of the duodenum, indicating superior mesenteric syndrome. Gastrofibroscopy revealed multiple hemorrhagic ulcers and numerous beadlike cystic lesions in the stomach. Laboratory examination results were notable for severe deficiencies in critical nutrients, including iron, zinc, proteins, and prealbumin, as well as undernutrition-associated endocrine complications such as hypothyroidism and hypogonadotropic hypogonadism. Excessive vomiting ceased after the endoscopic removal of stagnant gastric contents. Gastric pneumatosis improved after 3 days of supportive care.

• Journal of Chest Surgery
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• v.40 no.1 s.270
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• pp.79-82
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• 2007

Tracheobronchial rupture due to blunt chest trauma is an uncommon injury although the incidence is increasing. Early diagnosis and primary repair of tracheobronchial rupture not only restore a normal lung function but also avoid the difficulties and complications associated with delayed diagnosis and repair We present one case of the tracheal transsection caused by traffic accident. Patient suffered from progressive dyspnea, subcutaneous emphysema on the neck and anterior chest wall and tension pneumothorax at both sides were noted. Although both closed thoracostomy were done, massive air leakage through the chest tube continued and subcutaneous emphysema spread to the anterior abdominal wall and scrotum and the degree of dyspnea aggravated. With the impression of tracheobronchial injury, we performed the emergency operation. Preoperative bronchoscopy at the operation room was proceeded, which revealed the trachea was near totally transsected in transverse direction. Operation was performed through collar incisiion on the anterior neck, and the trachea was anastomosed with 4-0 $Vicryl^{(R)}$ interruptedly. Postoperative course were uneventful and patient discharged without any complications.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.387-392
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• 2017

When an infant has visited a hospital due to skull fracture, the rupture of a blood vessel, or skin wounds on the head resulted from an incident, accident, traffic accident, or disease, he/she becomes to undergo anterior/posterior and lateral skull imaging, which is a head test at the department of radiology. In the head test, if the adult skull imaging grid is applied to the imaging, the secondary radiation will be removed to enhance the contrast of the image. However, among the radiation exposure conditions, the tube voltage should be enhanced by 8~10 kVp leading to an increase in the patient exposure. The present study was conducted under assumption that if the same images can be obtained from infant skull imaging without using the skull imaging grid, the exposure dose will be reduced and the artifacts due to grid cut off can be prevented. The researcher measured the radiation dosage using a radiation meter and conducted the subjective evaluation (ROC, receiver operating characteristic) among medical image evaluation methods. Based on the results, when the images were taken without using the grid, the exposure dose was reduced by 0.019 mGy in the anterior/posterior imaging and by 0.02 mGy in the lateral imaging and the image evaluation score was higher by 4 points. In conclusion, if the images of the skulls of infants that visited the hospital are taken with out using the grid, the exposure dose can be reduced, the image artifacts due to grid cut off can be prevented, and the lifespan of the X-ray tube will be extended.

• Journal of Veterinary Clinics
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• v.33 no.4
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• pp.237-242
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• 2016

A 1.86 kg, 3-year-old, female, Maltese was presented to the Veterinary Medical Teaching Hospital of Seoul National University after being hit by a car. The patient was diagnosed with urinary bladder rupture, diaphragmatic hernia and fracture of ilium, tibia and fibula. Repair surgery was performed after stabilizing treatment. During the surgery, hypoxia was identified and it worsened after positive pressure ventilation (partial pressure of oxygen in arterial blood ($PaO_2$): 52 mmHg, pulse oximetry ($SpO_2$): 87%, arterial hemoglobin oxygen saturation ($SpO_2$): 85.8%). In addition to hypoxia, blood pressure decreased to 30 mmHg. Positive pressure ventilation was discontinued because hypoxia and hypotension were aggravated. After suturing the diaphragm, air was withdrawn to form negative pressure within the thorax. However, negative pressure was not attained despite continuous withdrawal of air. A thoracostomy tube was placed because tension pneumothorax was strongly suspected. The patient recovered through close monitoring with the tube for 3 days. Due to limitation of evaluation of the lung, predicting occurrence of tension pneumothorax is difficult in patient of diaphragmatic hernia. Therefore, it is recommended that indicators of tension pneumothorax should be closely monitored during diagnosis and repair procedures of diaphragmatic hernia.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.301-301
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• 2003

In current study, Nanocomposites are reinforced with carbon nanofiber, carbon nanotube and SiC, etc. Since the nano reinforcements have the excellent mechanical, thermal and electrical properties compared with that of existing composites, it has lately attracted considerable attention in the various areas. Cu have been widely used as signal transmission materials for electrical electronic components owing to its high electrical conductivity. However, it's size have been limited to small ones due to its poor mechanical properties. Until now, strengthening of the copper alloy was obtained either by the solid solution and precipitation hardening by adding alloy elements or the work hardening by deformation process. Adding the alloy elements lead to reduction of electrical conductivity. In this aspect, if carbon nanofiber is used as reinforcement which have outstanding mechanical strength and electric conductivity, it is possible to develope Cu matrix nanocomposite having almost no loss of electric conductivity. It is expected to be innovative in electric conducting material market. The unidirectional alignment of carbon nanofiber is the most challenging task developing the cooer matrix composites of high strength and electric conductivity. In this study, the unidirectional alignment of carbon nanofibers which is used reinforced material are controlled by drawing process and align mechanism as well as optimized drawing process parameter are verified via numerical analysis. The materials used in this study were pure copper and the nanofibers of 150nm in diameter and of 10∼20$\mu\textrm{m}$ in length. The materials have been tested and the tensile strength was 75MPa with the elongation of 44% for the copper. it is assumed that carbon nanofiber behave like porous elasto-plastic materials. Compaction test was conducted to obtain constitutive properties of carbon nanofiber Optimal parameter for drawing process was obtained by analytical and numerical analysis considering the various drawing angles, reduction areas, friction coefficient, etc. The lower drawing angles and lower reduction areas provides the less rupture of co tube is noticed during the drawing process and the better alignment of carbon nanofiber is obtained.

• Journal of Chest Surgery
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• v.42 no.2
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• pp.263-267
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• 2009

A pancreatico-pleural fistula (PPF), caused by rupture of a pancreatic pseudocyststectomy or obstruction of the pancreatic duct, is a rare condition. A 48-year-old man with chronic alcoholism was admitted with a massive pleural effusion. Pleural fluid studies revealed elevated amylase and lipase. A PPF complicated by a ruptured pancreatic pseudocyststectomy was diagnosed by computerized tomography scan. Although the symptoms improved with conservative management, (chest tube drainage, NPO, total parenteral nutrition, and a pancreatic secretion inhibitor), a distal pancreatectomy, including a pseudocystectomy and thoracotomy, were performed for an increasing size of the hemorrhagic pancreatic pseudocyststectomy and a recurrent hemorrhagic pleural effusion. There were no post-operative complications and the patient was discharged on post-operative day 27.

• Journal of the Korean Society of Safety
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• v.35 no.4
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• pp.84-91
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• 2020

The Korean nuclear industry developed the SPACE (Safety and Performance Analysis Code for nuclear power plants) code and this code adpots two-phase flows, two-fluid, three-field models which are comprised of gas, continuous liquid and droplet fields and has a capability to simulate three-dimensional model. According to the revised law by the Nuclear Safety and Security Commission (NSSC) in Korea, the multiple failure accidents that must be considered for accident management plan of nuclear power plant was determined based on the lessons learned from the Fukushima accident. Generally, to improve the reliability of the calculation results of a safety analysis code, verification work for separate and integral effect experiments is required. In this reason, the goal of this work is to verify calculation capability of SPACE code for multiple failure accident. For this purpose, it was selected the experiment which was conducted to simulate a Multiple Steam Generator Tube Rupture(MSGTR) accident with Passive Auxiliary Feedwater System(PAFS) operation by Korea Atomic Energy Research Institute (KAERI) and focused that the comparison between the experiment results and code calculation results to verify the performance of the SPACE code. The MSGR accident has a unique feature of the penetration of the barrier between the Reactor Coolant System (RCS) and the secondary system resulting from multiple failure of steam generator U-tubes. The PAFS is one of the advanced safety features with passive cooling system to replace a conventional active auxiliary feedwater system. This system is passively capable of condensing steam generated in steam generator and feeding the condensed water to the steam generator by gravity. As the results of overall system transient response using SPACE code showed similar trends with the experimental results such as the system pressure, mass flow rate, and collapsed water level in component. In conclusion, it could be concluded that the SPACE code has sufficient capability to simulate a MSGTR accident.